Progress 02/15/03 to 09/14/08
Outputs
OUTPUTS: Calcium sulfite, a common by-product of coal combustion and flue gas desulfurization, spontaneously converts to gypsum with exposure to air and water. The oxidation of sulfite to sulfate consumes oxygen and may have detrimental effects on plant root growth and soil microbial activity if calcium sulfite is land applied. Because the oxidation rate is pH dependent, greenhouse tests were conducted to evaluate the effects of calcium sulfite on wheat growth, soil enzyme activities, and the chemical properties of two soils with differing pH (4.0 vs. 6.2). Exchangeable calcium and water-extractable calcium and sulfate increased with application rate (0, 2.2, 4.4, and 8.8 Mg/ha) in both soils after 5 weeks indicating rapid oxidation of calcium sulfite when neither water nor oxygen was limiting. No changes in soil pH were measured. No effect on wheat growth and no significant differences in soil enzyme activities after 10 wks were noted with the pH 6.2 soil. In the acid soil, an application of 2.2 Mg/ha calcium sulfite increased wheat root growth and yield compared with the untreated control. In contrast, wheat growth and alkaline phosphatase and arylsulfatase activities were significantly inhibited by addition of 8.8 Mg/ha calcium sulfite because of rapid oxygen consumption and/or release of sulfur dioxide to the root environment....Ocoee Lake No. 3 is the first reservoir receiving suspended sediments contaminated with trace metals discharged with acid mine effluents in the Ducktown Mining District of Tennessee. Bottom sediments from the lake (0 to 5 cm) were sampled to assess the potential for future adverse environmental effects if no remediation activities are implemented. The sediments were found to contain a major fraction (173 g/kg) that was acid-soluble with high concentrations of relatively labile manganese, copper, zinc, and lead. Substantial release of trace metals from the sediment was observed with a modest decrease of pH from 6.4 to 5.9. Consequently, the metal-rich lake sediment should be considered as potentially hazardous to bottom-dwelling aquatic species and other organisms in the local food chain. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Many coal-fired electric utilities in the US use scrubbing technologies to reduce sulfur dioxide emissions during or after coal combustion. Wet flue gas desulfurization processes often generate large quantities of calcium sulfite that must be stockpiled and impounded as a waste product. The use of this material as a broadcast soil amendment would be a profitable alternative if agronomic benefits and environmental safety can be demonstrated. The results of this greenhouse investigation show that surface applications of calcium sulfite may be as effective as gypsum (a well know soil conditioner) for inhibiting crusting, improving water infiltration, and promoting the movement of calcium into acid subsoils with no negative impact on plant growth or soil microbial activity....Mining and processing of sulfide ore deposits often cause the release of large amounts of toxic trace metals into natural water systems, including lakes and reservoirs used for recreation. Most of these metals are sorbed to iron oxide particles that are also a product of mining. For this reason, metal-rich sediments have become a major concern worldwide because of the potential bioavailability and toxicity of some metal species to aquatic fauna and flora. This study demonstrated that trace metals associated with bottom sediments in Ocoee Lake No. 3 in eastern Tennessee were labile and mobilized by even a modest decrease in pH of the sediment pore water. Consequently, the sediment is a potential concern for ingestion by bottom-dwelling organisms. In addition, if the lake is dredged or the dam removed, the accumulated sediment may have to be treated for recovery of sorbed metals.
Publications
- Lee, G., Faure, G., Bigham, J.M., and Williams, D.J. 2008. Metal release from bottom sediments of Ocoee Lake No. 3, a primary catchment area for the Ducktown mining disrict. J. Environ. Qual. 37:344-352.
- Hita, R., Wang, H., Bigham, J.M., Torrent, J., and Tuovinen, O.H. 2008. Bioleaching of a pyritic sludge from the Aznalcollar (Spain) mine spillage at ambient and elevated temperatures. Hydrometallurgy 93:76-79.
- Lee, Y.B., Bigham, J.M., Dick, W.A., and Kim, P.J. 2008. Impact of FGD-calcium sulfite and gypsum on soil microbial activity and wheat growth. Soil Sci. (in press).
|
Progress 01/01/07 to 12/31/07
Outputs
Transient, unsaturated horizontal column experiments were conducted to assess clay mineralogy impacts on electrostatic processes affecting nitrate mobility. Replicated tests were conducted on quartz sand; artificial mixtures of sand and various clay minerals including kaolinite, illite, and montmorillonite; and two natural soil materials with organic matter removed. In each test, a 200 mg/L nitrate solution was injected at the inlet of a dry column. Nitrate concentrations for the quartz sand were consistently near the 200 mg/L injection level within the wetted portion of the columns, indicating that electrostatic interactions were negligible. Anion adsorption processes in a 25% kaolinite-75% sand mixture produced a result in which the nitrate concentrations adjacent to the inlet of the columns were approximately 20% greater than that of the injected solution. Anion exclusion was the dominant electrostatic interaction affecting nitrate mobility in the remaining
clay-sand mixtures and the natural soil materials, all of which contained 2:1-type clay minerals. As predicted, nitrate concentrations near the column inlets in these systems were 11 to 19% less than the injected solution concentration, whereas concentrations near the wetting front were greater by factors of 1.7 to 5.4. Calcium sulfite is a common by-product of coal-fired utilities and can spontaneously oxidize to form gypsum when land applied. A study was conducted to examine the effects of application rate and soil pH on the oxidation of calcium sulfite under laboratory conditions involving ambient temperatures and water contents at field capacity. Oxidation measured by release of sulfate to solution decreased with increasing application rate in the range of 1.0 to 4.0 g calcium sulfite per kg of soil. At 1.0 to 3.0 g/kg, maximum oxidation was achieved after 21 - 28 d. At 4.0 g/kg, maximum sulfate release was delayed until day 49. The oxidation and release of sulfate from soil
amended with 3 g/kg calcium sulfite increased markedly with decreasing soil pH. After only 3 d incubation, the concentrations of sulfate in aqueous leachates were 77, 122, 170, 220, and 229 mg/L for initial soil pH values of 7.8, 6.5, 5.5, 5.1, and 4.0, respectively. Soil organic carbon (SOC) retention is a function not only of climate, vegetation, drainage, and management interactions but also of intrinsic soil properties such as texture, mineralogy and structure. Three soils of the Brazilian savannah formed under similar climate, vegetation, and slope but with contrasting texture were sampled to 1-m depth and characterized for particle size distribution, mineralogy and SOC concentration. Positive linear relations were obtained between SOC and clay plus silt contents. Quantitative clay mineralogical analyses also showed that bulk SOC pools were well correlated with oxalate-extractable Fe oxides in the topsoil and oxalate-extractable Al oxides in the subsoil, but mineralogical
controls were secondary to texture in importance because texture also depends on clay content.
Impacts
Nitrate from fertilizer applications to farm fields is commonly responsible for the contamination of shallow aquifers. The transport of nitrates is through the soil profile where nitrate mobility is governed by electrostatic interactions between nitrate anions (negatively charged) and charged surface sites (+ or -) on soil clay minerals and organic matter. Anion adsorption occurs when nitrate ions become attached to positively charged sites on soil particles; whereas, anion exclusion occurs when nitrate ions are repelled from soil particle surfaces and move at a faster rate than the overall pore water. Unsaturated horizontal column experiments were conducted to assess the impacts of clay mineralogy (type of clay) on electrostatic processes affecting nitrate mobility in artificial sand-clay mixtures and natural soil materials. Data from these experiments confirmed that computer modeling programs are capable of predicting nitrate movement through the soil profile,
especially if such programs are improved by incorporating nitrate adsorption and exclusion processes under unsaturated flow conditions. Calcium sulfite is a major component of flue gas desulfurization (FGD) residues produced by the lime-based scrubbing processes employed at many coal-fired electric utilities. FGD-calcium sulfite is usually treated as a waste product that is mixed with fly ash for storage in landfills. When exposed to air and water, calcium sulfite will also convert to more soluble gypsum, a common soil amendment for agriculture. The use of FGD-calcium sulfite in production agriculture would provide an attractive alternative to disposal if benefits and environmental safety can be demonstrated. Laboratory leaching experiments were therefore conducted to determine the effects of application rate and soil pH on the conversion of calcium sulfite to gypsum. It was determined that the conversion is fast at pH values below those suitable for agronomic crop production.
Although rates are slower at more optimal pH values, the conversion to gypsum still occurs within 3 to 7 weeks with loadings commonly used for surface applications of gypsum. Annual crops can thus benefit from soluble calcium and sulfate within the rooting zone if calcium sulfite is surface applied in advance of spring planting. Soil organic carbon (SOC) has been studied for its influence on soil properties and functions such as aggregation, fertility, and biological activity. Growing concern with global warming has brought additional interest because of the possibility of removing carbon dioxide from the atmosphere and sequestering part of the carbon as SOC. Soil texture and mineralogy have long been recognized for their impact on basic soil chemical and physical properties, but their influence on SOC retention and dynamics has not been carefully investigated, especially in tropical soils. Studies of the Central Brazilian biome suggest that soil texture and mineralogy (type of clay
minerals) not only influence soil aggregation but also control SOC levels in managed ecosystems.
Publications
- Wang, H., Bigham, J.M., Jones, F.S., and Tuovinen, O.H. 2007. Synthesis and properties of ammoniojarosites prepared with iron-oxidizing acidophilic microorganisms at 22-65 C. Geochim. Cosmochim. Acta 71:155-164.
- Lee, Y.B., Bigham, J.M., Dick, W.A., Jones, F.S., and Ramsier, C. 2007. Influence of soil pH and application rate on the oxidation of calcium sulfite derived from flue gas desulfurization. J. Environ. Qual. 35:298-304.
- Cheng, C.-M., Walker, H.W., and Bigham, J.M. 2007. Influence of pH on the leaching kinetics of a fixated flue gas desulfurization (FGD) material. J. Environ. Qual. 36:874-886.
- Allred, B.J., Brown, G.O., and Bigham, J.M. 2007. Nitrate mobility under unsaturated flow conditions in four initially dry soils. Soil Sci. 172:27-41.
- Allred, B.J., Bigham, J.M., and Brown, G.O. 2007. The impact of clay mineralogy on nitrate mobility under unsaturated flow conditions in initially dry soil. Vadose Zone J. 6:221-232.
- Wang, H., Bigham, J.M., and Tuovinen, O.H. 2007. Oxidation of marcasite and pyrite by iron-oxidizing bacteria and archaea. Hydrometallurgy 88:127-131.
- Zinn, Y.L., Lal, R., Bigham, J.M., and Resck, D.V.S. 2007. Edaphic controls on soil organic carbon retention in the Brazilian Cerrado: Texture and mineralogy. Soil Sci. Soc. Am. J. 71:1204-1214.
- Zinn, Y.L., Lal, R., Bigham, J.M., and Resck, D.V.S. 2007. Edaphic controls on soil organic carbon retention in the Brazilian Cerrado: Soil structure. Soil Sci. Soc. Am. J. 71:1215-1224.
|
Progress 01/01/06 to 12/31/06
Outputs
Phytotoxic levels of Zn were observed in a pyrite (FeS2)-rich sludge deposited by the collapse of the Aznalcollar mine talings dam in southwestern Spain. The oxidative dissolution of ZnS in the sludge and other pyritic samples was examined. Flow-through oxidation experiments showed that i) 5 and 17% of the sludge Fe and Zn, respectively, were in soluble form because the natural sample had been partially oxidized in the field; ii) the oxidation rates of the residual pyrite and sphalerite were similar; iii) the over-all ZnS oxidation rate was relatively unaffected by the addition of calcium carbonate (calcite) to mollify the acidity generated by pyrite oxidation; and iv) poorly crystalline Fe oxides containing occluded Zn hydroxicarbonates were formed in the presence of calcite. The rate of oxidation of reference ZnS greatly increased when it was incorporated in the sludge or in a reference pyrite matrix. This enhancement was due to a galvanic interaction because pyrite
oxidation was depressed in the presence of ZnS. Therefore, factors affecting particle contact , such as surface area, strongly influence the rate of sphalerite oxidation in pyritic mine tailings. Sulfate-reducing bacteria (SRB) play a major role in the precipitation of metal sulfides (ZnS, CuS, PbS, etc.) in the environment. Biogenic copper sulfide formation was examined in cultures of SRB and compared to chemically initiated CuS precipitation. Mixed cultures of SRB were incubated at 22, 45, and 60 C in nutrient solutions that contained Cu sulfate. Abiotic reference samples were produced by reacting uninoculated liquid media with Na sulfide solutions under otherwise identical conditions. Covellite (CuS) was the only mineral found in the precipitates. The covellite was less crystalline in the biogenic precipitates than in the abiotic samples based on XRD peak widths and peak to background ratios. These results suggested that bacterial cells inhibited the nucleation steps that led to
crystal formation. Incubation at elevated temperatures improved the crystallinity of the biotic specimens but not those formed abiotically.
Impacts
Our work demonstrates that the oxidation of metal sulfides occurring in mine tailings is a complex process that may lead to phytotoxic levels of various metals in the environment. In the case of mine tailings containing sphalerite (ZnS), the release of soluble, plant-available Zn is enhanced through particle-to-particle contact with other sulfide minerals, especially pyrite (FeS2). The rapid oxidation of ZnS in such sediments indicates a need for the rapid adoption of remediation techniques, such as the addition of calcium carbonate (agricultural lime). The use of calcite amendments has little influence on the oxidation rate of ZnS but does result in the conversion of soluble Zn to relatively insoluble hyroxicarbonate minerals, thereby eliminating concerns about the release of Zn at levels toxic to plants.
Publications
- Hita, R., Torrent, J., and Bigham, J.M. 2006. Experimental oxidative dissolution of sphalerite in the Aznalcollar sludge and other pyritic matrices. J. Env. Qual. 35:1032-1039.
- Garcia, Jr., O., Bigham, J.M., and Tuovinen, O.H. 2006. Oxidation of isochemical FeS2 (marcasite-pyrite) by Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans. Minerals Eng. 20:98-101.
- Gramp, J.P., Sasaki, K., Bigham, J.M., Karnachuk, O.V., and Tuovinen, O.H. 2006. Formation of covellite (CuS) under biological sulfate-reducing conditions. Geomicrobiology J. 23:613-619.
- Wang, H., Bigham, J.M., and Tuovinen, O.H. 2006. Formation of schwertmannite and its transformation to jarosite in the presence of aciophilic iron-oxidizing microorganisms. Materials Sci. Eng. 26:588-592.
- Weatherington-Rice, J., and Bigham, J.M. 2006. Buried pre-Illinoian-age lacustrine deposits with "green rust" colors in Clermont County, Ohio. Ohio J. Sci. 106:35-44.
|
Progress 01/01/05 to 12/31/05
Outputs
The effect of various clay minerals on polysaccharide sorption was evaluated under different environmental conditions involving pH, ionic strength, and cation type. Xanthan, an anionic polysaccharide, was used to represent soil microbial exopolysaccharides. Highly significant effects (P > F < 0.0001) were observed for type of clay mineral, pH, xanthan concentration, and electrolyte concentration. Sorption decreased with increase in pH from 3 to 8, consistent with an increase in the negative charge of both the clay surface and xanthan molecules. The presence of 10 mmol/L calcium nitrate made sorption possible at pH values above the pKa of xanthan. Divalent cations (Sr, Ca, and Mg) enhanced sorption to a greater degree than monovalent cations (K, Na, and Li) at the same ionic strength, showing that cations participated in the binding of xanthan to clay surfaces. Sorption was smallest with kaolinite and greatest with a low-charge smectite where layer charge originated
mostly in the tetrahedral positions. Average sorption was two times greater for smectite than for kaolinite, indicating that clay mineral composition also influenced polysaccharide sorption. The effects of elevated pH, ionic strength, and temperature on sediments in the vadose zone are important in understanding contaminant transport from storage tanks at nuclear waste facilities like the Hanford site. Biotite dissolution and its impact on Cr(VI) reduction was investigated under simulated high level waste conditions. Biotite dissolution increased with NaOH concentrations in the range of 0.1 to 2 mol/L. There was a corresponding release of K, Fe, Si and Al to solution with Si and Al showing a complex pattern due to the formation of secondary zeolite minerals. Dissolved Fe concentrations were an order of magnitude lower than the other elements, possibly due to the formation of green rust. The reduction of Cr(VI) to Cr(III) also increased with increased NaOH concentration. A homogeneous
reduction of chromate by Fe(II) released through biotite dissolution was probably the primary pathway responsible for this reaction. Greater ionic strengths increased biotite dissolution and increased Fe(II) release and Cr(VI) removal. The results indicated that high level wastes could cause phyllosilicate dissolution and the formation of secondary precipitates that would have a major impact on radionuclide and contaminant transport in the vadose zone. Ultrasound at 20 kHz was used to investigate the desorption of Hg(II) from aluminum oxide particles. Results showed that at short time intervals ultrasound enhanced Hg(II) release at pH 4.0 compared to hydrodynamic mixing. The higher the input power of sonication, the higher the desoprtion of Hg(II). With longer times, less desorption occurred by ultrasound than by mixing, and mass balance measurements demonstrated that desorbed Hg(II) was resorbed back to the particles. X-ray photoelectron spectroscopy and the formation of solutions
supersaturated with Al indicated that Hg(II) occlusion by aluminum hydroxide precipitation was the mechanism of resorption.
Impacts
Our work demonstrates that the types of clay minerals occuring in soils and sediments may influence the amount of carbon that can be stored or sequestered. This information is important to understand the potential use of soils and sediments for countering the current trends of global warming caused by the release of carbon dioxide and other greenhouse gases to the atmosphere through fossil fuel combustion. Soil minerals may also react with radioactive wastes leaking from high level nuclear waste sites in this and other countries. The nature of these reactions can influence the movement of specific chemical species to the ground water. Sonication techniques using ordinary ultrasound may be a viable means to remove some contaminant species from soils and sediments.
Publications
- Bigham, J.M., Kost, D.A., Stehouwer, R.C., Beeghly, J.H., Fowler, R., Traina, S.J., Wolfe, W.E. and Dick, W.A. 2005. Mineralogical and engineering characteristics of dry flue gas desulfurization products. Fuel 84:1839-1848.
- Dontsova, K.M. and Bigham, J.M. 2005. Anionic polysaccharide sorption by clay minerals. Soil Sci. Soc. Am. J. 69:1026-1035.
- He, Y.T., Bigham, J.M. and Traina, S.J. 2005. Biotite dissolution and Cr(VI) reduction at elevated pH and ionic strength. Geochim Cosmochim. Acta 69:3791-3800.
- He, Z., Traina, S.J., Bigham, J.M. and Weavers, L.K. 2005. Sonolytic desorption of mercury from aluminum oxide. Environ. Sci. Technol. 39:1037-1044.
- Rhoton, F.E. and Bigham, J.M. 2005. Phosphate adsorption by ferrihydrite-amended soils. J. Environ. Qual. 34:890-896.
|
Progress 01/01/04 to 12/31/04
Outputs
The mineralogy and geochemical stability of ochreous sediments accumulated in a compost wetland constructed in 1990 for acid mine drainage treatment were studied. Intact sediment cores were collected in 1996 and 2000 from an area that had accumulated 33 cm of ochre. Solids were subsequently separated from pore waters by centrifugation and analyzed using X-ray diffraction (XRD), infrared spectroscopy, scanning electron microscopy, and wet chemical techniques. The solid phase had an average Fe content of 585 g/kg and was predominantly schwertmannite in the upper portion of the sediment column. Transformation of schwertmannite to goethite occurred with depth. The rate of transformation was calculated to be 30 mol/m3/yr in the initial 6 yr of sedimentation as compared to 10 mol/m3/yr for the 4-yr period from 1996 to 2000. Pore water composition was affected by this mineral transformation through the production of acidity and the release of iron and sulfate. Consequently,
the sediment column was not a static environment...The weathering of ground phlogopite, a trioctahedral mica, by placing it in contact with cultures of heterotrophic (Bacillus cereus) and acidophilic (Acidithiobacillus ferrooxidans) bacteria was studied. Analyses of the phlogopite sample before and after 24 weeks of contact with B. cereus cultures revealed a decrease in characteristic XRD peak intensities over time, indicating acid dissolution and possible complexation of released metals by carboxylic acids in the heterotrophic leaching system. No new solid-phase products were detected . The A. ferrooxidans culture also accelerated chemical dissolution of the phlogopite but, in addition, formed an interstratified mineral product with expanding layers produced by expulsion of interlayer K. Interlayer K removal was presumably enhanced by precipitation of jarosite in the strongly acid media...The clay fractions of many tropical soils consist of kaolinite, gibbsite, iron oxides, and small
amounts of expandable, 2:1 clay minerals. Whereas good analytical techniques are available for quantification of kaolinite, gibbsite, and the iron oxides, no satisfactory procedure has been developed for analysis of the expandable clay minerals in these soils. Thermal analyses of 56 clay fractions from Brazilian soils that were pretreated to remove iron oxides gave statistically significant (P less than 0.0001) linear correlations with the percentage of 2:1 clay minerals and the cation exchange capacities of the whole soil materials. Water content can thus be used as a tool to estimate the quantity of 2:1 minerals in lieu of more complicated procedures.
Impacts
Our work demonstrates that the weathering of minerals commonly found in soils and sediments is often enhanced by the metabolic activity of associated microorganisms. Weathering reactions and the release of weathering products to the environment under experimental conditions that consider only chemical factors are probably not realistic indicators of natural conditions.
Publications
- Costa, A.C.S., Bigham, J.M., Tormena, C.A. and Pintro, J.C. 2004. Clay mineralogy and cation exchange capacity of Brazilian soils from water contents determined by thermal analysis. Thermochimica Acta 413:73-79.
- Gagliano, W.B., Brill, M.R., Bigham, J.M., Jones, F.S. and Traina, S.J. 2004. Chemistry and mineralogy of ochreous sediments in a constructed mine drainage wetland. Geochim. Cosmochim. Acta 68: 2119-2128.
- Styriakova, I., Bhatti,T.M., Bigham, ,J.M., Styriak, I., Vuorinen, A. and Tuovinen, O.H. 2004. Weathering of phlogopite by Bacillus cereus and Acidithiobacillus ferrooxidans. Can. J. Microbiol. 50: 213-219.
- Dontsova, K.M., Norton, L.D., Johnston, C.T. and Bigham, J.M. 2004. Influence of exchangeable cations on water adsorption by soil clays. Soil Sci. Soc. Am. J. 68:1218-1227.
|
Progress 01/01/03 to 12/31/03
Outputs
Soil aggregates low in organic matter and clay are susceptible to disintegration at low rainfall energies. A study was conducted to evaluate the effectiveness of by-product ferrihydrite (amorphous ferric hydroxide) from a wastewater treatment facility as an agent for stabilizing soil aggregates. Five soil materials with a wide range of physical and chemical properties were amended with by-product ferrihydrite at rates equivalent to 0, 0.34, 3.36, 16.80 and 33.60 Mg/ha, packed to a depth of 7.6 cm in plexiglass cylinders, and then exposed to simulated rainfall at an intensity of 64 mm/h for 1.5 h. Erodibility data indicated that as ferrihydrite concentration increased from 0 to 16.80 Mg/ha on acid soil materials, infiltration increased an average of 21.5% while runoff and soil loss decreased 20 and 40%, respectively. Conversely, infiltration decreased 37% while runoff and soil loss increased 21 and 34%, respectively, for alkaline soil materials. Sediment size
distributions measured at these same ferrihydrite rates indicated that the greater than 250, and 250 to 53 micron fractions increased 24 and 22%, respectively, for acid soil materials and decreased 15 and 14%, respectively, in alkaline soil samples. The less than 53 micron fraction decreased 21% in acid soils and increased 46% in alkaline soils. These results suggest that ferrihydrite develops a net positive charge in acid soil environments that leads to the formation of electrostatic bonds with negatively charged soil particles and an increase in water stable aggregation. Conversely, ferrihydrite becomes negatively charged in alkaline soil materials and causes dispersion and aggregate instability. Thus, ferrihydrite appears to be an effective amendment for reducing runoff and soil loss from acid soils at amendment rates between 3.36 and 16.80 Mg/ha.
Impacts
Wastewater treatment facilities in some parts of the United States produce large quantities of amorphous ferric hydroxide (ferrihydrite) as a by-product of water treatment. This material is usually landfilled; however, our study demonstrates that land applications of ferrihydrite have the potential to improve soil aggregation and reduce surface runoff and erosion.
Publications
- Rhoton, F.E., Roemkens, M.J.M., Bigham, J.M., Zobeck, T.M. and Upchurch, D.R. 2003. Ferrihydrite influence on infiltration, runoff, and soil loss. Soil Sci. Soc. Am. J. 67:1220-1226.
|
Progress 01/01/02 to 12/31/02
Outputs
Ochreous precipitates composed mostly of schwertmannite or ferrihydrite were isolated from mine drainage and were found to contain 6.1 to 69.8 g/kg As. Schwertmannite formation was favored at pH 3 to 4, but its structure was degraded at high As levels. A series of co-precipitates were prepared from mixed Fe arsenate/sulfate solutions to define the limits of schwertmannite stability. Schwertmannite was replaced as the dominant phase by a poorly crystalline Fe(III)-hydroxy arsenate (FeOHAs) when As/Fe mole ratios exceeded 0.15. The FeOHAs gave an X-ray diffraction pattern similar to that obtained from a pure Fe(III)-arsenate (As/Fe = 1.0) with broad peaks at 0.30 and 0.16 nm. The FeOHAs possessed a magnetic hyperfine field of 41.9 T at 4.2 K that was intermediate to those of schwertmannite (46.1 T) and the Fe(III)-arsenate (24.8 T). These data indicate a strong disruptive effect of arsenate on magnetic ordering and structure development. Geochemical modeling of mine
drainage waters using standard solubility products may be inappropriate due to the formation of a FeOHAs surface phase on mineral preicipitates.. The pHs of mine waters were estimated from the spectral reflectance of stream sediments composed mostly of chemical precipitates. Sediments derived from acidic waters contained primarily schwertmannite and goethite while near neutral waters produced ferrihydrite. These minerals were spectrally separable and could be used to accurately predict stream water pH. Spectral results were used to analyze airborne digital multispectral video (DMSV) imagery for several sites. The high spectral resolution of the DMSV sensor allowed for precise mapping of the mine drainage sediments. The results indicate that airborne spectrometers may be used to accurately classify streams impacted by mine drainage after appropriate spectral libraries are developed.The properties of a flue gas desulfurization grout (FGDG) prepared as a sealant for attenuating drainage
from an underground mine were studied. The FGDG was prepared as a 1:1 mixture of fly ash and filter cake with hydrated lime (50 g/kg) added to improve handling. The hydrated lime was composed mostly of calcite, portlandite, lime, and brucite (515, 321, 55, and 35 g/kg, respectively); trace element concentrations were low except for Sr (343 mg/kg). The filter cake was found to contain mostly hannebachite (786 g/kg) with smaller quantities (< 10 g/kg) of calcite, quartz, brucite, and gypsum. Except for B (218 mg/kg) and Cu (75 mg/kg), trace element concentrations were comparable to those in the hydrated lime. The fly ash contained both magnetic (222 g/kg) and non-magnetic (778 g/kg) fractions. The former was composed of hematite, magnetite, and glass (272, 293, and 287 g/kg, respectively); whereas the latter was enriched in glass, quartz and mullite (515, 243, and 140 g/kg, respectively). Etching of the fly ash with 1% HF showed that 60 to 100% of trace elements were contained in the
glass although some metals (Co, Cr, and Mn) were enriched in the magnetic phase. The FGDG contained 314 g/kg hannebachite, 147 g/kg ettringite, and 537 g/kg insoluble phases (mullite, quartz, hematite, magnetite and glass).
Impacts
The reported results may be used to improve the efficiency of trace metal recovery using biological leaching processes. The results may also help understand processes by which toxic trace elements are transported by solids suspended in waters draining landscapes contaminated by mining and smelting activities.
Publications
- Bigham, J.M., Fitzpatrick, R.W. and Schulze, D.G. 2002. Iron oxides. p. 323-366. In: Dixon, J.B., and D.G. Schulze (ed.) Soil mineralogy with environmental applications. SSSA Book Ser. no. 7, Soil Sci. Soc. Am., Madison, WI.
- Gagliano, W.B. and Bigham, J.M. 2002. Acid mine drainage. p.1-4. In: Lal, R. (ed.) Encyclopedia of soil science. Marcel Dekker, New York, NY.
- Munk, L.A., Faure, G., Pride, D.E. and Bigham, J.M. 2002. Sorption of trace metals to an aluminum precipitate in a stream receiving acid rock-drainage; Snake River, Summit County, Colorado. Appl. Geochem. 17:421-430.
- Carlson, L., Bigham, J.M., Schwertmann, U., Kyek, A. and Wagner, F. 2002. Scavenging of As from acid mine drainage by schwertmannite and ferrihydrite: A comparison with synthetic analogues. Environ. Sci. Technol. 36:1712-1719.
- Rhoton, F.E., Bigham, J.M. and Lindbo, D.L. 2002. Properties of iron oxides in streams draining the loess uplands of Mississippi. Appl. Geochem. 17: 409-419.
- Lee, G., Bigham, J.M. and Faure G. 2002. Removal of trace metals by coprecipitation with Fe, Al, and Mn from natural waters contaminated with acid mine drainage in the Ducktown Mining District, Tennessee. Appl. Geochem. 17: 569-581.
- Ketterings, Q.M., van Noordwijk, M. and Bigham, J.M. 2002. Soil phosphorus availability after slash-and-burn fires of different intensities in rubber agroforests in Sumatra, Indonesia. Agric. Ecosystems Environ. 92:37-48.
- Laperche, V. and Bigham, J.M. 2002. Quantitative chemical and mineralogical characterization of flue gas desulfurization by-products. J. Environ. Qual. 31:979-988.
- Williams, D.J., Bigham, J.M., Cravotta III, C.A., Traina, S.J., Anderson, J.E. and Lyon, J.G. 2002. Assessing mine drainage pH from the color and spectral reflectance of chemical precipitates. Appl. Geochem. 17:1273-1286.
|
Progress 01/01/01 to 12/31/01
Outputs
Microbiological weathering of a research-grade mica mineral, phlogopite, was studied using ferrous sulfate media that were inoculated with an acidophilic iron-oxidizing bacterium, Thiobacillus ferrooxidans. Weathering due to dissolution was monitored by analysis of Si, Al, Fe, K, Na, Mg, and Ca in the leach solutions and in chemical controls at pH 1.0, 1.5 and 2.0. Structural alterations of phlogopite were anlayzed by x-ray diffraction. At pH 2, the oxidation of Fe(II) by T. ferrooxidans was accompanied by the formation of jarosite within 7 days of incubation at 22 C. The precipitation of jarosite was coupled with partial alteration of phlogopite to vermiculite and an interstratified (mixed-layer) phlogopite/vermiculite. Similar results were obtained with chemical controls containing 120 mM ferric sulfate. The data suggested that K incorporated into jarosite was released from interlayer positions in phlogopite; thus, jarosite constituted a sink for K. The formation of
jarosite and expansible layer silicate phases was pH-dependent. At pH < 1.5, jarosite was not formed and phlogopite weathering was due to chemical dissolution without detectable structural alteration....The sorption of trace metals to precipitates formed by neutralization of three natural waters contaminated with acid mine drainage (AMD) was studied. The three water samples were obtained from the Ducktown Mining District, Tennessee, were strongly acidic (pH 2.2 to 3.4), and had different chemical signatures based on the mole fractions of dissolved Fe, Al, and Mn. One sample was Fe-rich (87.5 mole % Fe), another was Al-rich (79.4 mole % Al), and the other was Mn-rich (51.4 mole % Mn). In addition, these waters had high concentrations of trace metals including Zn, Cu, Co, Ni, Pb, and Cd. Neutralization of the AMD-contaminated waters in the laboratory caused the formation of either schwertmannite at pH < 4 or ferriydrite at pH > 4. Both phases were identified by XRD analyses of
precipitates from the most Fe-rich water. At about pH 5, Al-rich precipitates were formed. Manganese compounds were precipitated at about pH 8. The removal of trace metals depended on the precipitation of these compounds, which acted as sorbents. Accordingly, the pH for 50% sorption ranged from 5.6 to 7.5 for Zn, 4.6 to 6.1 for Cu, 5.4 to 7.7 for Ni, 5.9 to 7.9 for Co, 3.1 to 4.3 for Pb, and 5.5 to 7.7 for Cd. The pH dependence of sorption arose not only because of changes in the sorption coefficients of the trace metals but also because the formation and composition of the sorbent was controlled by the pH, the chemical composition of the water, and the solubilities of the oxyhydroxide-sulfate complexes of Fe, Al, and Mn.
Impacts
The reported results may be used to improve the efficiency of trace metal recovery using biological leaching processes. The results may also help understand processes by which toxic trace elements are transported by solids suspended in waters draining landscapes contaminated by mining and smelting activities.
Publications
- Bigham, J.M., Bhatti, T.M., Vuorinen, A. and Tuovinen, O.H. 2001. Dissolution and structural alteration of phlogopite mediated by proton attack and bacterial oxidation of ferrous iron. Hydrometallurgy 59:301-309.
- Bhatti, T.M., Bigham, J.M. and Tuovinen, O.H. 2001. Bacterial and chemical oxidation of marcasite and pyrite. p. 617-625. In: Ciminelli, V.S.T. and Garcia Jr., O. (eds.). Biohydrometallury: fundamentals, technology and sustainable development, part B. Elsevier, London.
|
Progress 01/01/00 to 12/31/00
Outputs
The effects of fire severity from slash-and-burn agriculture on the mineralogy, color and fertility of Oxisols in Sumatra, Indonesia were investigated. Samples were collected over two depths (0-5 and 5-15cm) at locations exposed to 100, 300, 600 and >600 C surface temperatures during open burns. Soils under forest and slashed vegetation were collected as controls. The pre-burn soil mineralogy was dominated by kaolinite, gibbsite, anatase, and goethite. Changes in soil properties with burning were most pronounced in the 0-5 cm layer. Burning the topsoil led to coarser textures, especially at temperatures exceeding 600 C. Heat reduced the gibbsite and kaolinite concentrations and converted goethite into ultra fine maghemite, thus increasing the magnetic susceptibility of the samples. The conversion of goethite did not take place until water in the samples had evaporated. Addition of organic matter to soil with a low organic C content before heating increased the
magnetic susceptibility indicating that organic matter was necessary (and limiting) for the complete conversion of goethite. Coarse-grained magnetite particles were present prior to and after the burning and, therefore, were not pyrogenic. Magnetic susceptibility measurements were highly discriminatory among heat treatments; whereas, x-ray diffraction was much less sensitive to fire-induced changes in mineralogy. Our research showed that severe burning had drastic effects on soil mineralogy, but changes should also be expected at lower fire intensities. Field burning caused Munsell values and chromas to decrease and hues to become yellower with heating to 600 C, especially in the top 5 cm of the soil. At higher temperatures, soil C was mostly depleted and the soil matrix reddened. Laboratory studies showed similar results with static heating. Colors of burned areas in the field did not change significantly over a 12-week period following the burn. Fire induced the formation of
aggregates with exteriors that had lower values and chromas and slightly redder hues than the interiors. Organic matter removal from burned samples by chemical oxidation did not alter the color. Exchangeable Ca, Mg, K, and Na increased with fire intensity; whereas, exchangeable acidity and Al decreased. Phosphorus availability showed an increase at low-to-medium fire intensities and a decrease at the most intense burn levels. Within 3 months following the field burn, exchangeable cations and Bray-1 P had decreased to almost pre-burn levels; whereas, Al and extractable acidity had increased to starting concentrations. Using post-burn color measurements to predict the spatial variability of soil fertility was limited by the fact that fertility changed rapidly following the burn whereas color parameters did not. Moreover, color changes were highly dependent on the duration of exposure at a given temperature.
Impacts
(N/A)
Publications
- Bigham, J.M. 2000. Linkages between mineralogy and the geochemistry of acid sulfate waters. p 17-19. In: D. Rammlmair, J. Mederer, Th. Oberthuer, R.B. Heimann and H. Pentinghaus, Eds. Applied mineralogy in research, economy, technology, ecology and culture. Vol. 1. Proceed. Sixth Int. Cong. Applied Mineralogy, ICAM 2000, Goettingen, Germany, A.A. Balkema Press, Rotterdam.
- Costa, A.C., Sambatti, J.A., Bigham, J.M., Sengik, E. and Tormena, C.A. 2000. Phosphate adsorption in synthetic ferrimagnetic minerals. 2000. p. 231. Agron. Abst., Am. Soc. Agron., Madison, WI.
- Costa, A.C., Sambatti, J.A., Muniz, A.S., Bigham, J.M., Pintro, J.C. and Silva, M.A. 2000. Chemical and mineralogical characteristics of ferrimagnetic synthetic minerals. p. 372. Agron. Abst., Am. Soc. Agron., Madison, WI.
- Bigham, J.M. and Nordstrom, D.K. 2000. Iron and aluminum hydroxysulfates from acid sulfate waters. p. 351-403. In: C.N. Alpers, J.L. Jambor, and D.K. Nordstrom, Eds. Sulfate minerals - crystallography, geochemistry and environmental significance. Reviews in Mineralogy, Vol. 40. Miner. Soc. Amer. and Geochem. Soc., Washington, D.C.
- Ketterings, Q. and Bigham, J.M. 2000. Soil color as an indicator of slash-and-burn fire severity and soil fertility in Sumatra, Indonesia. Soil Sci. Soc. Am. J. 64:1826-1833.
- Ketterings, Q.M., Bigham, J.M. and Laperche, V. 2000. Changes in soil mineralogy and texture caused by slash-and-burn fires in Sumatra, Indonesia. Soil Sci. Soc. Am. J. 64:1108-1117.
- Ketterings, Q.M., Van Noordwijk, M. and Bigham, J.M. 2000. The benefits of a reduction in fallow period: An example from Indonesia. p. 47. Agron. Abst., Am. Soc. Agron., Madison, WI.
|
Progress 01/01/99 to 12/31/99
Outputs
Many soils developed from volcanic rocks in the tropics exhibit spontaneous magnetization caused by the presence of fine-grained maghemite (gamma iron oxide), but few attempts have been made to quantify or characterize this mineral. To that end, clays were separated from freely drained soils derived from acid (greater than 63% silica), intermediate (54-66% silica), and basic (less than 54% silica) igneous rocks produced by the Parana flood volcanism in southern Brazil. The sample set included soils with a wide range of pedogenic development on different landscape positions. The iron oxide mineralogy of these samples was examined by using a combination of selective dissolution, magnetic susceptibility, and x-ray diffraction (XRD) techniques. Hematite (alpha iron oxide) and maghemite were the primary Fe oxides in Oxisols, Ultisols, and Alfisols developed from basic rocks; whereas goethite (FeOOH) was dominant in all other soils, especially those formed from acid or
intermediate rocks. The association of maghemite with basic rock materials suggests that it primarily formed by oxidation of lithogenic magnetite. A strong, positive correlation was obtained between mass specific magnetic susceptibility of the clay fractions and maghemite contents estimated by XRD. Either method could be used for quantitative analyses, but magnetic susceptibility was more sensitive than XRD at low maghemite concentrations (< 2 wt.%). The clay-sized maghemites were superparamagnetic and showed frequency dependent variations of 10-15% in mass specific magnetic susceptibility. The maghemites also had low unit cell constants that, if attributed entirely to replacement of Fe by Al, would correlate with Al substitutions in the range of 5 to 16 mole %. Selective dissolution of the soil maghemites was achieved by treatment of iron oxide concentrates with 1.8 M sulfuric acid at 75 C for 2 hours.
Impacts
(N/A)
Publications
- Costa, A.C.S. da, Bigham, J.M., Rhoton, F.E., and Traina, S.J. 1999. Quantification and characterization of maghemite in soils developed from volcanic rocks in southern Brazil. Clays Clay. Min. 47:466-473.
- Ketterings, Q.M. 1999. Fire as a land management tool in Sepunggur, Sumatra, Indonesia. Can farmers do without it? Ph.D. Dissertation, The Ohio State Univ. 285 p.
- Ketterings, Q.M., Van Noordwijk, M., and Bigham, J.M. 1999. Impact of slash-and-burn fire intensity on P availability. p. 49. Agron. Abst., Am. Soc. Agron., Madison, WI.
- Ketterings, Q.M., Slater, B.K., Van Noordwijk, M., and Bigham, J.M. 1999. Impact of slash-and-burn fires on spatial variability of soil properties. p. 51. Agron. Abst., Am. Soc. Agron., Madison, WI.
|
Progress 01/01/98 to 12/31/98
Outputs
Late Wisconsinan beach ridges corresponding to different stages of ancestral Lake Erie are common land forms in northwest Ohio. Bright red soils (Vaughnsville series) with Munsell hues of 5YR or redder have formed on the north (lake) side of some ridges and contrast strongly with other soils of the region. Soil scientists have attributed the red coloration to precipitation of poorly crystalline iron oxides from seepage waters at the base of the beach ridges, but other sources are possible. The mineralogy of a typical red soil was compared with that of an associated yellow pedon to investigate their contrasting pigmentation. Acid ammonium oxalate extractions of soil and clay materials from both pedons produced similar quantities of soluble iron. The residue colors were also unaltered. These results indicated that poorly crystalline iron oxides, such as ferrihydrite, were not major sources of pigmentation in either soil. Diffuse reflectance spectroscopy led to the
identification of both hematite (red) and goethite (yellow) in the red soil, but only goethite occurred in the companion profile. Mass specific magnetic susceptibilities of the red materials also indicated the presence of a ferrimagnetic component. Subsequent high gradient magnetic separations of the clays enabled the identification of maghemite by x-ray diffraction. Maghemite may form in soils by burning of soil organic matter in the presence of other iron oxides or by oxidation of detrital magnetite. Incremental heating of the yellow soil materials from 250 to 850 C at 2 hr intervals produced colors and magnetic susceptibilities similar to those of the natural red soil; however, the depth and uniform spatial distribution of red coloration in the Vaughnsville soils suggest that they have not been heavily impacted by burning. Oxidation of fine grained magnetite occurring as lag deposits along the former beach faces is a more likely origin for the red pigmentation and magnetic
properties of these soils.
Impacts
(N/A)
Publications
- Lepper, J.A.W. 1998. Iron oxide mineralogy and coloration of late Wisconsinan Maumee II beach ridge soils in northwestern Ohio. M.S. Thesis, The Ohio State Univ. 209 p.
- Ketterings, Q.M., Bigham, J.M., and Laperche, V. 1998. Effects of forest burning on soil mineralogy: Results from field experiments in Indonesia. p. 321. Agron. Abst., Am. Soc. Agron., Madison, WI.
|
Progress 01/01/97 to 12/31/97
Outputs
Seasonal pore water and sediment samples were collected in the first cell of an artificial wetland designed to passively treat acidic drainage from an abandoned coal mine in Athens Co., OH. From 1991 to 1997, 36 cm of ochreous sediment accumulated over a cell base initially lined with 30 cm of agricultural limestone topped with 38 cm of mushroom compost. No visible evidence of the compost remained after 6 yr. Pore water pH was 2.5 to 3.0 at the sediment surface and decreased slightly with depth before increasing to near neutral values at the base of the sediment column. Redox potentials were positive throughout most of the column during summer months but decreased during winter and were always strongly negative at the base of the sediment. Seasonal variations in dissolved Fe(II) mirrored changes in redox potential with concentrations approaching 1250 mg/L during winter. X-ray diffraction analyses revealed that the most recent precipitates were composed primarily of
schwertmannite and that a transformation of schwertmannite to goethite occurred with depth. As a consequence, solid phase sulfur decreased and dissolved sulfate increased with depth in the sediment column. These results suggest that schwertmannite is unstable with respect to goethite because of the seasonally reduced conditions that are apparently characteristic of the wetland.
Impacts
(N/A)
Publications
- JONES, F.S., ET AL. 1997. Banded fabric in a buried loamy zone on Illinoian-age outwash terraces of S. Ohio, USA. Proc. 10th Int. Work. Meet. Soil Micromorphology, Moscow, Russia. July 8-13, 1996. Van Gils B.V., Wageningen, The Netherlands.
- BRILL, M.R., TRAINA, S.J. AND BIGHAM J.M. 1997. Sediment mineralogy and geochemistry in a constructed acidic mine drainage wetland. p. 190. Agron. Abst., Am. Soc. Agron., Madison, WI.
|
Progress 01/01/96 to 12/30/96
Outputs
A study of the Birkbeck-Reesville-Ragsdale soil association was conducted to determine the origin of expandable clay minerals (smectites) in a toposequence of soils derived from Peoria loess. Chemical and x-ray analyses showed that the smectite in these soils was dioctahedral with a layer charge of 0.36 to 0.38 per half unit cell. The smectite comprised 50 percent or more of the total clay in the B and C horizons, and no changes in mineral properties could be attributed to differences in natural soil drainage. The presence of smectite in the C horizons indicated a detrital origin and suggested that Peoria loess was an important source of expandable clay minerals in soils of western Ohio. The geochemistry and mineralogy of sediments from 28 coal mine drainage sites in eastern Ohio were evaluated to determine stability relationships among important mineral precipitates. Schwertmannite, the most common mineral phase, was commonly associated with goethite. A solubility
window of log IAP equals 18.0 plus 2.5 was calculated for schwertmannite formed in the pH range of 2.8 to 3.2. The metastable nature of schwertmannite was confirmed in a long-term (1739 day) aqueous equilibrium study wherein a pure, synthetic specimen was completely transformed to goethite. The pH and computed activity of Fe(III) in the final equilibrium solutions yielded a log K equals 1.40 plus 0.01 for goethite.
Impacts
(N/A)
Publications
- BIGHAM, J.M., SCHWERTMANN, U., TRAINA, S.J., WINLAND, R. L., AND WOLF, M. 1996. Schwertmannite and the chemical modeling of iron in acid sulfate waters. Geochim. Cosmochim. Acta 60:2111-2121.
- BURRA, L., SMECK, N. E., AND BIGHAM, J.M. 1996. Origin and properties of smectitein loess-derived soils of western Ohio. Soil Sci. Soc. Am. J. 60:1961-1968.
- RHOTON, F.E., BIGHAM, J.M., SMECK, N. E., AND LINDBO, D.L. 1996. Interstratified clay mineral distribution in lower Mississippi River Valley loess deposits. p. 261. Agon. Abst., Am. Soc. Agron., Madison, WI.
|
Progress 01/01/95 to 12/30/95
Outputs
Biological leaching is commonly used to recover trace metals from sulfide ores. Galena (PbS) and sphalerite (ZnS) are common constituents of such materials. The biological leaching of research-grade specimens of galena and sphalerite by both Thiobacillus ferrooxidans and Thiobacillus thiooxidans was studied to characterize the oxidation reactions and to identify the mineral weathering products. In T. ferrooxidans experiments with galena, the leach solutions maintained an almost constant pH of 2. In T. thiooxidans cultures, the pH initially increased from 2 to 4, but the oxidation reaction eventually became acid producing. Anglesite (PbSO4) was detected by x-ray diffraction as a solid-phase product of galena dissolution, whereas elemental sulfur was not. When ferrous sulfate was added as a supplementary energy source for T. ferrooxidans, jarosite (KFe3(OH)6SO4) was produced. In sphalerite experiments, solid-phase reaction products were not detected in unsupplemented
media, whereas minor amounts of elemental sulfur accumulated in FeSO4-amended media with or without the presence of T. ferrooxidans. Amendment of T. thiooxidans-inoculated sphalerite media with elemental sulfur enhanced acid production but not Zn dissolution. T. ferrooxidans was more efficient than T. thiooxidans in the oxidation of both galena and sphalerite.
Impacts
(N/A)
Publications
|
Progress 01/01/94 to 12/30/94
Outputs
Acid mine drainage produces large volumes of ochreous precipitates of unknown composition. A survey of mine drainage in Ohio revealed that schwertmannite, a new mineral recently approved by the International Mineralogical Association, was the most common precipitate from effluents in the pH range 3.0 to 4.5. Jarosite was an ancillary phase in drainage with pH less than 3.0, whereas ferrihydrite was produced by rapid hydrolysis of Fe (III) at pH greater than 6. Goethite occurred as a trace or secondary component in many sediments and was probably an alteration product of other mineral phases...Bioleaching is commonly used to recover trace metals from sulfidic ores. The oxidative leaching of arsenopyrite by Thiobacillus ferrooxidans at room temperature produced jarosite, elemental sulfur, and an amorphous ferric arsenate with only two broad x-ray diffraction peaks. The pH (1.5-2.0) remained stable, but the redox potential of the reaction medium increased from 300 to 500
mV over a 40 d period. A moderately thermoacidophilic mixed culture containing Thiobacillus ferrooxidans at 22 C, and the oxidation was accompanied by a nearly stoichiometric release of Fe and As. The redox potential increased from 400 to 600 mV during arsenopyrite oxidation by the thermoacidophiles over a 20 d leach period. Jarosite, elemental sulfur, and amorphous ferric arsenate were also formed under these conditions.
Impacts
(N/A)
Publications
|
Progress 01/01/93 to 12/30/93
Outputs
Pyrrhotite (FE1-XS) is a reactive component of many sulfide ores that are mined for metal recovery. The biological leaching of research-grade pyrrhotite by Thiobacillus ferroxidans was studied to characterize the oxidation process and to identify the mineral weathering products. An initial phase of acid consumption and decrease in redox potential was followed by an acid-producing phase and an increase in redox potential. Elemental S was one of the first products of pyrrhotite degradation detected by X-ray diffraction. Pyrrhotite oxidation also yielded jarosite (KFe3(SO4)2(OH)6), goethite (alpha-FeOOH), and schwertmannite (KFe8O8(OH)6SO4) as solid-phase products. Pyrrhotite was mostly depleted after 14 days, whereas impurities in the form of pyrite (cubic FeS2) and marcasite (orthorhombic FeS2) accumulated in the leach residue. Sample preparation is a major obstacle in clay mineralogical analyses by X-ray diffraction. A suction apparatus for plating multiple clay
specimens onto ceramic tiles was designed and fabricated to facilitate the production of oriented clay aggregates. Nodules cemented by Fe and Mn oxides are abundant in many fragipan soils derived from loess and have been used as an indicator of erosion. Nodules from a number of fragipan soils were isolated and analyzed for mineralogical composition. Goethite was the only Fe oxide identified by X- ray diffraction; no crystalline Mn oxides were detected.
Impacts
(N/A)
Publications
|
Progress 01/01/92 to 12/30/92
Outputs
Mineralogical changes resulting from the bacterial leaching of a black schist ore sample were studied using a mixed culture of acidophilic, Fe- and S-oxidizing thiobacilli in shake flasks. The main sulfide phases in the schist were pyrrhotite and pyrite with lesser amounts of sphalerite, pentlandite, and chalcopyrite. The primary silicate phases were quartz, mica (phlogopite) and feldspars (anorthite and microcline). Solubilization of Cu, Ni, and Zn from the sulfide minerals was accelerated in the inoculated suspensions compared to sterile reference systems. Pyrrhotite was oxidized faster than pyrite and was associated with elemental S accumulation. The accumulation was transient in inoculated systems because of eventual bacterial oxidation of S. K-jarosite formation resulting from the bacterial oxidation of Fe-sulfides was coupled with mica alteration to vermiculite. The results suggested that K-jarosite was a sink for K released during mica weathering. Jarosite and
vermiculite were not detected under comparable abiotic conditions. After 100 days of bacterial leaching, gypsum was produced through the release of Ca from anorthite. No structural alteration of feldspar was evident from x-ray diffraction studies.
Impacts
(N/A)
Publications
|
Progress 01/01/91 to 12/30/91
Outputs
A series of reduced-charge clays were prepared by multiple (up to 8) heat treatments of Mg-saturated hectorites (standard clay sample SHCa-1) at 250(degree)C. Cation exchange capacity (CEC) measurements and the formation of interlayer alkylammonium complexes showed that decreases in layer charge occurred with each successive heat treatment. Decreases in structural Li and increases in structural Mg were associated with the charge reduction. Fluorescence measurements from adsorbed quinoline indicated that the hectorite surface was acidified during charge reduction. Relative intensities of the OH and SiO stretch bands in Fourier transform infrared (FTIR) spectra suggested that the surface acidity may have arisen through deprotonation of OH groups in the mineral structure; however, thermogravimetric analyses revealed no significant differences in OH content. The CEC, layer charge, FTIR and thermal data all support the conclusion that substitution of exchangeable Mg for
octahedral Li occurred with heating, thereby yielding a more talc-like structure.
Impacts
(N/A)
Publications
|
Progress 10/01/89 to 09/30/90
Outputs
Ochreous precipitates and associated drainage waters were collected from abandoned coal works at 28 locations in eastern Ohio. Chemical compositions of the precipitates were compared with the source solutions to evaluate the effects of pH, organic carbon and ionic strength on solid-phase composition and trace metal distribution. The pH and ionic strength of the effluents ranged from 2.6 to 7.8 and 0.01 to 0.11 mol L, respectively. Associated precipitates consisted mainly of poorly crystalline iron oxyhydroxides. Mean Fe, SO(4), Al and Si contents of the precipitates were 494, 129, 30 and 7 g kg, respectively. Si contents increased with increasing pH of the source solutions, suggesting pH-dependent adsorption. In contrast, SO(4) and Al appeared to be influenced both by precipitation and adsorption reactions. Partition coefficients for As, B, Ba, Co, Cu, Cr, Mn, P, and Zn showed preferential accumulation by the solid phase with mean log K(d) values ranging from 2.8
for Cu to 6.3 for As. Mn, Co, and Zn showed increased partitioning into the solid phase with increasing pH and decreasing ionic strength. Cu appeared to be strongly associated with organic matter, and a weaker but positive relationship was also observed with Co and Zn. No effects of pH, ionic strength or organic carbon were observed for any other trace elements.
Impacts
(N/A)
Publications
|
Progress 01/01/89 to 12/30/89
Outputs
A poorly crystallized oxyhydroxysulfate of Fe has been identified as the primarycomponent of ochreous precipitates from sulfate-rich mine waters having pH in the range of 2.5 to 4.0. The compound is characterized by rapid dissolution in acid (pH 3.0) ammonium oxalate; an Fe/S mole ratio ranging from 5 to 8; yellowish brown (9.0-10.OYR) color; a fibrous morphology; a high specific surface area (175-225 m/g); and a broad, 8-line x-ray diffraction profile. Analyses of synthetic analogs prepared by hydrolysis of 0.02 M FeC1(3) solutions containing up to 2000 mug/ml SO(4) show the material to have a tunnel structure skin to that of akaganeite (Beta-FeOOH). Sulfate occurs both as a bridging element between Fe atoms lining adjacent walls of the tunnels and as a specifically adsorbed surface component. Extraction of the tunnel SO(4) destabilizes the structure and causes the compound to transform to goethite (alpha-FeOOH) under ambient conditions. Moessbauer spectra taken at
4.2K yield hyperfine fields lower than those of even the most poorly crystallized iron oxides, indicating that SO(4) inhibits magnetic ordering. A tetragonal unit cell with a(o) = 1.065 and c(o) = 0.604 nm is proposed to describe the structure. The corresponding unit cell formula is Fe(1)(6)O(1)(6)(OH)(1)(2)(SO(4))(2) but may range to Fe(1)(6)O(1)(6)(OH)(1)(0)(SO(4))(3) depending upon degree of saturation of tunnel and surfacesites with SO(4).
Impacts
(N/A)
Publications
|
Progress 01/01/88 to 12/30/88
Outputs
A detailed study of clay mineral weathering in a Crider soil from southern Ohio was conducted using total chemical, density separation, alkylammonium exchange, and X-ray diffraction techniques. Total Al contents of the <0.2 m clays were highest near the interface between a thin loess mantle and an underlying paleosol at a depth of 65 cm; in contrast, CECs and total Mg, K and Fe contents were lowest in this region indicating a zone of intensified weathering. An interstratified 1:1-2:1 mineral was concentrated in the 2.03 g/cm density fraction following density gradient centrifugation of <0.2 m clays from the loess-paleosol contact. Alkylammonium exchange of the 2.03 g/cm density fraction indicated that the 2:1 component of the interstratified phase was vermiculite...Reductions in exchangeable Mg were observed with liming of seven acid soil materials from southern and eastern Ohio. Decreases were obtained over a range of equilibrium pH values; however, the effect was
clearly enhanced by increasing soil reaction to near pH 7.0. Decreases in exchangeable Mg in those materials limed to near pH 7.0 ranged 17 to 34% of that present before liming. The reduction in exchangeable Mg was positively correlated with several Al fractions including exchangeable, organically chelated, and poorly crystallized inorganic species; however, the best correlation was achieved with exchangeable Al indicating that loss of exchangeable Mg was due to the coprecipitation of Mg with Al upon liming.
Impacts
(N/A)
Publications
|
Progress 01/01/87 to 12/30/87
Outputs
Decreases in layer charge are commonly observed when 2:1 expandable clays are staurated with Li and heated. Direct measurements of exch. Li after heating a series of Li-smectites to 250 for 12 hr led to overestimates of charge reduction due to entrapment of Li in collapsed interlayers. Sequential washings with MgC1(2) and ethanol removed entrapped Li, nd subsequent determinations of exch. Mg provided accurate measurements of reduced charge. The CEC reductions observed in dioctahedral samples equalled octahedral charge values derived from published mineral formulae, and interlayer charge estimates obtained by alkylammonium exchange confirmed that these reductions were a consequence of uniform decreased in octahedral layer charge. Dioctahedral specimens retained 1 to 0 meq/100g of non-exch. Li in excess of CEC reduction and were acidified in direct proportion to their total Fe contents, apparently as a result of the deprotonation of structural hydroxyl groups. Mild
acid treatment reprotonated these hydroxyl groups, released excess Li, and resulted in total Li contents comparable to measured CEC reductions...To seasonally wes soils from S.W. Ohio were studied in order to relate micromorphology to pedogenic processes associated with fluctuating H(2)0 tables and alternating conditions of ox. Horizons from 50-80 cm were extensively degraded and were characterized by many Fe-Mn nodules and gray, eluvial zones surrounding islands of brow sesquioxidic material with inundulic plasmic fabric.
Impacts
(N/A)
Publications
|
Progress 01/01/86 to 12/30/86
Outputs
High speed centrifugation with a large-scale zonal rotor and a linear, tetrabromoethane-ethanol density gradient was utilized to fractionate the <0.2 um clay materials from 3 soils. Hematite, goethite, and lepidocrocite were concentrated 4- to 10- fold in the high density range (>2.4 Mg/m), while the low density fractions (<2.20 Mg/m) were depleted in reductant-soluble Fe. Density gradient centrifugation also produced useful mineralogical separations of soil phyllosilicates. In particular, smectite was concentrated in the 1.8-2.1 Mg/m density range whereas the 2.1-2.3 Mg/m fractions were enriched with kaolinite, vermiculite, and clay mica. Electron microscopy and x-ray diffraction analyses indicated that Fe-oxides were present as discrete particles...Laboratory studies were conducted to examine the formation of mixed Mg-A1 hydroxide (hydrotalcite) as a possible mechanism for preferential retention of exchangeable Mg relative to Ca in many soils of S.E. Ohio. When
A1-saturated soil samples were leached with mixed Ca and Mg solutions, 2.5 to 4.0 times more Mg than Ca was retained. Selected soil clays containig 2:1 layer silicates were subsequently A1 saturated, suspended in dilute Mg solution, and titrated with NaOH to a pH of 9.5. Titration curves showed a pronounced buffer region between pH 8.3 and 8.5 that was attributed to the formation of mixed Mg-A1 hydroxide. After equilibrating for 6 weeks, x-ray diffraction analyses of the clays revealed diffuse reflections at 8.2 and 4.
Impacts
(N/A)
Publications
|
Progress 01/01/85 to 12/30/85
Outputs
Two Typic Hapludalfs formed from red and gray sedimentary rocks in S.E. Ohio were sampled and analyzed to determine the origin and significance of their contrasting coloration. Field morphology and elemental analyses indicated that both soils were polygenetic and had developed in approx. 30 cm of late Wis. loess overlying paleosols formed in residuum from shale or mudstone. The two soils were similar with respect to most chemical, physical and mineralogical characteristics. X-ray diffraction studies of Fe-oxide concentrates obtained by high gradient magnetic and density separation techniques revealed that goethite was the only Fe oxide present in the yellowish-brown profile formed from gray shale. Chemical analyses demonstrated that most of the goethite had formed from Fe released by pedogenic weathering of layer silicate minerals. Pigmentation in the dusky red soil was due primarily to the presence of lithogenic hematite, and variations in profile color
reflected differences in the proportion of hematite, goethite and lepidocrocite. The concentration of silicate Fe in the dusky red soil was constant with depth. Gray mottles diagnostic of restricted drainage were absent in the red profile; however, the presence of pedogenic lepidocrocite was indicative of seasonally anaerobic conditions. A procedure was developed to achieve multiple CEC measurements from clay samples using a commercial mechanical extractor.
Impacts
(N/A)
Publications
|
Progress 01/01/84 to 12/30/84
Outputs
Detailed mineralogical analyses of Clermont and Avonburg soils from southwesternOhio have shown that weathering of mica in the glacial till has resulted in the oxidation of structural Fe (II), the release of interlayer K, and the formation of a low-charge vermiculite that expands when solvated with ethylene glycol but not with glycerol; a pronounced accumulation of goethite in the lower sola of both soils reflects a permanent, oxygenated water table perched above the dense basal till; concentrations of lepidocrocite and goethite within 75 cm of the soil surface are indicative of a seasonal water table subject to alternating redox conditions. The periodic mobilization of Fe in this zone has also resulted in the formation of hydroxy Al/Fe interlayers and a possible recharge of octahedral Fe in the expandable 2:1 layer silicates...Studies of Quaternary sediments in the Teays River Valley of southern Ohio have demonstrated that Teays-age lacustrine deposite (Minford
Clays) can be distinguished from younger lacustrine materials on the basis of higher clay content, more micaceous mineralogy, and an alemental Zr content that is 2 to 4 times lower. Discriminant statistical analyses of data from a total of 180 samples indicated that the Minford Clays could also be distinguished from all other valley-fill deposits on the basis of texture and mineralogy; however, younger lacustrine sediments in overlying stratigraphic units could not be clearly separated from associated colluvium, alluvium or loess using the same criteria.
Impacts
(N/A)
Publications
|
Progress 01/01/83 to 12/30/83
Outputs
Black Fork Creek in Morgan Co. was selected for evaluating the solution chemistry of Fe in streams receiving acid coal mine drainage. H(2)O samples from a point source and a 2 km downstream section of the receiving stream were examined. Total SO(4), total Fe, Eh, and pH of the effluent were 4500 ug ml, +314 mV and 2.9, respectively. Sample pH and Eh increased slightly at all downstream sites. Total Fe showed a 10-fold decrease in the downstream waters. Ferrous Fe accounted for 95% of the dissolved Fe load in the acid effluent but decreased to only 10% in H(2)O from the site farthest downstream. Dissolved FeRG3 showed the opposite trend, and UV-spectroscopic analyses indicated that most of the FeRG3 was in the form of hydroxy complexes, especially Fe(OH)yRG. All parameters indicated that Fe in the acid mine effluent was rapidly oxidized and precipitated upon entering the receiving stream...A procedure was developed to etch the surface of soil thin sections for coupled
optical and electron microscope analysis. Following examination with a standard petrographic microscope, soil thin sections (30 um) were immersed in methylene chloride for two minutes at room temperature. Partial dissolution of the epoxy impregnating medium exposed soil fabric for visual examination using the scanning electron microscope and for elemental analysis with an energy dispersive X-ray system.
Impacts
(N/A)
Publications
|
Progress 01/01/82 to 12/30/82
Outputs
Streams receiving acid SO(4) drainage from abandoned coal mines in S.E. Ohio commonly contain large quantities of colloidal Fe oxide. To study the properties and formation of this colloid, a series of poorly crystallized Fe oxides were synthesized by slow hydrolysis of Fe (NO(3))(3) solutions containing 0 to 2000 Mug/ml SO(4). Experimental parameters were designed to mimic conditions observed in the field. In the absence of SO(4) up to 3 weeks were required to produce a recognizable precipitate, whereas an immediate solid phase was formed in solutions containing SO(4). In each case, the aged precipitate was identified as ferrihydrite (Fe(5)HO(8). 4H(2)O); however, X-ray diffraction and selective dissolution analyses showed a progressive decrease in crystallinity of the ferrihydrite with added SO(4). Color of the synthates became yellower with increasing SO(4) and ranged from 10R 3/4 (0 Mug/ml SO(4)) to 7.5YR 5/8 (2000 Mug/ml SO(4)). A parabolic relationship was
observed between surface area of the precipitates and SO(4) level; a max. of 232 m 2/g was achieved in the presence of 1000 Mug/ml SO(4). These results indicate that SO(4) conc. may be an important factor determining local variations in the nature and reactivity of colloidal precipitates from acid mine effluents. The lab. synthates most similar to natural precipitates collected in S.E. Ohio were those formed in the presence of 1000 to 1500 Mug/ml SO(4)...
Impacts
(N/A)
Publications
|
Progress 01/01/81 to 12/30/81
Outputs
The Black Fork Creek Watershed in Morgan Co., Ohio was studied to determine the impact of acid coal mine drainage on water and sediment quality. Conc. of Fe, Al, and SO(4) averaged 0.5, 0.1, and 30 Mug/ml, respectively, during low flow periods. The pH was 6.7. Corresponding levels of Fe, Al, and SO(4) in streams with acid drainage were 128, 43, and 1004 Mug/ml, respectively; pH's ranged from 2.7 to 4.9. Low-flow bottom sediments from the reference areas contained 4.9% clay, 0.8% organic C, and 0.06% total S; average values from polluted areas were 10.2, 2.2, and 0.31%, respectively. By contrast, 2- to 3-fold increases in extractable Fe were observed in bottom sediment clays (less than 2 Mum) from polluted areas. Pyrophosphate Fe increased from 0.2 to 0.5%, oxalate Fe increased from 2.2 to 9.1%, and CBD-extractable Fe increased from 3.6 to 11.6%. The colloidal Fe oxide responsible for these increases was identified as proto-ferrihydrite... X-ray diffraction
analyses of several loess-capped paleosols in southern Ohio led to the recognition of an unusual clay mineral species in profile samples collected near the loess-paleosol contact. The mineral yielded a broad XRD line in the 8A region which was stable with standard chemical and thermal pretreatments to a temperature of 550C. The mineral was concentrated in the less than 0.2 Mum size fraction and appeared to be of pedogenic origin. It was tentatively identified as a kaolinite interstratified with mica/smectite.
Impacts
(N/A)
Publications
|
Progress 01/01/80 to 12/30/80
Outputs
Suspended sediment samples collected in a survey of the Muskingum River and its tributaries were found to be low in dissolved P (0.004-0.154 Mug/ml) but were relatively high in total organic carbon (2.5-4.9%). Nitrate-n varied from 0-3 Mug/ml and NH(3)-N concentrations were all less than 0.5 Mug/ml. The sediments contained 40-50% each of clay and silt and less than 5% sand. Pyrophosphate, oxalate, and CBD-extractable Fe in the clay fractions ranged from 0.5-2.5%, 0.8-5.9%, and 2.0-6.1%, respectively. Corresponding extractable Al contents varied from 0.1-04%, 0.2-0.5%, and 0.3-0.6%. Major silicate clay components included kaolinite, clay mica, Al-interlayered vermiculite and interstratified 2:1 species. Little variation in clay mineralogy was noted throughout the basin. Studies of loess-covered landscapes in Southeastern Ohio often revealed buried paleosols within the zone of modern soil formation. In many cases, the loess/paleosol contacts coincided with
fragipan horizons and/or mineralogical degradation. Discriminant analysis techniques using various physical, chemical and mineralogical parameters were tested as means of distinguishing loess from siltstone residua and lacustrine silts. In general, contents of Zr, Ti, K, and Ti/Zr in the 5-50 Mum fractions were the most reliable indicators of lithology. Clay mineralogical analyses of 61 samples were completed in support of the Ohio Soil Survey Program.
Impacts
(N/A)
Publications
|
Progress 01/01/79 to 12/30/79
Outputs
The influence of Fe-oxides on the particle density and charge characteristics ofsoil clays was evaluated using less than 0.2-MUm clays with secondary Fe contents ranging from 7 to 14$. Particle densities were determined before and after selective removal of free Fe-oxides with citrate-bicarbonate-dithionite and after extraction of the clays with boiling alkali to dissolve layer silicates. Both direct and indirect measurements gave Fe-oxide particle densities that ranged from 3.47 to 4.27 g/cc. Differences between samples were related to the type and relative amounts of Fe minerals present (goethite and hematite) and to the degree of Al(III) substitution in the oxide structures. Type or amount of Fe-oxide had no apparent effect on charge characteristics determined by serial potentiometric titrations. All clays were variable charge systems with points of 0 charge in the pH range 3.5 to 4.0. Total K contents were determined for 371 clays (less than 2 MUm) from
fine-textured (35% clay) Ohio soils. This data will be used to evaluate total K(2)O as a criterion for distinguishing between illitic and mixed mineralogy classes for soils in clayey or clayey-skeletal particle size families. Clay mineralogical analyses of 12 additional samples were completed in support of the Ohio Soil Survey program. A study of 4 soils in the ancient Teays River Valley revealed the presence of buried paleosols. The upper boundaries of these paleosols corresponded closely with modern fragipan horizons.
Impacts
(N/A)
Publications
|
Progress 01/01/78 to 12/30/78
Outputs
Clay mineraological analyses of soils, suspended runoff materials, and unconsolidated bottom sediments from six watersheds in the Maumee River Basin revealed a preferential transport of soil clay components during runoff events and a subsequent sorting of suspended components within the stream system. Specifically, increases in expandable minerals (soil, 14%; runoff, 19%; sediment, 27%) an illite (soil, 48%; runoff, 48%; sediment, 56%) and decreases in vermiculite (soil, 23%; runoff, 17%; sediment, 9%) and quartz (soil, 15%; runoff, 10%; sediment, 9%) were observed. Fine clay contents paralleled expendable mineral contents, increasing progressively from soil to runoff to sediment. Clays equilibrated in situ with bottom sediments of the Maumee River for periods of up to one year showed slight increases in surface area, but no significant mineralogical alterations/transformations were observed. Under laboratory conditions (25 C, N(2) atmosphere), substantial increases
in amorphous iron content were observed for A-horizon clays equilibrated with bottom sediments over a 12-week period. Clay mineral characterization of 23 samples was completed in support of the Ohio soil survey program.
Impacts
(N/A)
Publications
|
Progress 01/01/77 to 12/30/77
Outputs
Iron oxides are important scavengers of phosphates and heavy metals in natural waters. Acid ammonium oxalate and dithionite- citrate-bicarbonate (DCB) extractions of bottom sediments from the maumee River gave abnormally high ratios of "amorphous" to total secondary iron oxides. The granulometric distributions of oxalate and DCB extractable iron in selected samples were subsequently determined. With both extractants, the greatest quantities of iron were removed from the clay (less than 2 um) fractions. Magnetic separations of other size fractions revealed unusually equal to high concentrations of magnetite. Magnetite, as compared to other crystalline iron oxides, is readily soluble in acid ammonoim oxalate and probably accounts for the high oxalate/dithionite ratios obtained from the river sediments. In addition, the oxalate solubilities of several soil and sediment magnetites were found to be substantially greater than that of a standard mineral sample of
comparable particle size. The acid ammonoim oxalate procedure was also demonstrated to be photosensitive, therefore, extractions should always be performed in the dark or under controlled light conditions... Clay mineral characterization of 10 samples was completed in support of the Ohio soil survey program. Grain counts of sand subfractions from samples of 5 proposed mine-spoil areas were perfromed to determine the correct mineralogy class. One soil was siliceous, the remainder were mixed.
Impacts
(N/A)
Publications
|
Progress 01/01/76 to 12/30/76
Outputs
Mineralogical analyses of suspended sediment samples from the Maumee River revealed increasing quartz content on moving downstream due to the flocculation of mica and expandable clay mineral components during fluvial transport...Clays which were equilibrated in bottom sediments in the Maumee River for periods of up to 6 months showed little evidence of weathering...Clays in surface horizons at the intersections of a grid in small sloping watersheds near Coshocton revealed a wide range in mineralogical composition...Elemental composition of sand and silt fractions from 3 Aquolls which was determined to access parent material uniformity revealed apparent lithologic discontinuities in all 3 pedons. Thin section examinations of fine gravel and sand fractions revealed thedisintegration of shale in the solum. Elemental composition of the shale indicated that shale disintegration may account for the change in elemental composition which was attributed to a lithologic
discontinuity...Examinations ofthin sections from the upper B horizons of Cambridge and Venango pedons providedevidence for an argillic horizon above the fragipan which is not consistent withtheir present classification...Additional progress was made in the use and interpretation of X-ray microradiography as a useful investigative tool.
Impacts
(N/A)
Publications
|
Progress 01/01/75 to 12/30/75
Outputs
Five series of dark-colored poorly drained soils of Western Ohio currently classified as Aquolls, Aquells, and Aquepts were investigated to determine the origin of clay maximum in A and B horizons. Particle-size and thin-section analyses indicate that none of the soils have argillic horizons; these soils will be reclassified in view of this fact. Clay mineral analyses suggests decreasing depth functions of vermiculite and montmorillonite with increasing mica contents; montmorillonite which is absent in calcareous lower C horizons ispresent in calcareous B3 and upper C horizons. Shale components are numerous incalcareous C horizons but absent or infrequent in the solum. Above data suggest several multiple working hypothesis that may be advanced to explain clay maximum: a lithologic discontinuity within the solum; downslope redistribution of eroded sediments with increased clay contents derived from these upslope its;in situ neoformation of clay under favorable high
base-charged conditions; disintegration of shale lithics in the solum. Further work will attempt to determine which of these postulates are most plausible. Pedon variability studies are continuing to determine expected sampling errors in data and the best method of sampling soils. Clay mineral characterization has been completedfor 35 other samples in support of the soil survey program.
Impacts
(N/A)
Publications
|
Progress 01/01/74 to 12/30/74
Outputs
Differences in genesis of B horizons of soils in Northeastern Ohio are closely allied to physical, chemical, and mineralogical properties of the parent till deposits. In illitic parent materials, 30% clay on a non-carbonate basis represents a delicate balance point between soils with argillic horizons versus soils with fragipans. Clay contents in parent tills above 30% yield soils with argillic horizons, while those with less than 30% yield fragipans.... Bottom sediments from agricultural regions of NW Ohio occur from headwater to mouth reaches of the Maumee River and tributaries. Bottom sediments are more extensive downstream, particularly upstream from reservoir impoundment structures. The following are characteristic of these sediments: they range in texture from sandy loam to clay depending on source area and downstream transit;have from 13 to 59% (averaging 34%) of the total clay in the form of water-stable sand and silt aggregates; have calcite/dolomite
ratios of about 1:1contrasted to 2 to 3:1 for geologic materials; contain carbonate levels ranging from nil to 14% (averaging 4.7%) contrasted to values of 20 to 25% for geologic materials; have illitic clay mineralogy with secondary amounts of vermiculite, chlorite, expandables and quartz and (6) have organic carbon values ranging from1.8 to 4.6% (averaging 2.8%) with little evidence of downstream enrichment.
Impacts
(N/A)
Publications
|
|