Progress 10/01/04 to 09/30/09
Outputs
OUTPUTS: The main goals of the project were to determine the extent of plant availability of metals from land application of wastes and/or derived products from wastes containing elevated amounts of heavy metals, and how effective chemical and biological extractions were in reducing soil metal concentration and bioavailability. Studies pursued for accomplishing the goals included examining metal contents of various types of soil amendment including phosphate fertilizers produced from rock phosphate containing elevated amounts of Cd, trace elements fertilizers, and soil acidifying agents produced from mine tailings. In cooperation with Washington State Department of Agriculture, we studied the bioavailability of metals in those soil amendments by examining the growth response to increased rates of the soil amendments and uptake of metals by different types of plants under greenhouse and field conditions. We also examined the effectiveness of lime application and soil washing with dilute chelate solution with or without calcium in reducing the accessibility of metals to plants, and in cooperation with Washington State Department of Ecology, examined the adaptability and effectiveness of a hyperaccumulator in accumulating Pb and As from soils contaminated with elevated amounts of Pb and As. Based on the results of this research, we gave presentations on the potential impacts of the soil amendments on soil quality and plant productivity to growers and researchers in the private and state agencies, graduate students at various universities, and scientists at national and international conferences. We also disseminated the research results through publications on conference proceedings, and national and international refereed journals. 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
Although Cd in the phosphate rock was not readily available to lettuce, it was so when rock phosphate was transformed into mostly water-soluble triple superphosphate (TSP). This enhancement in Cd bioavailability resulted as acidification of phosphate rock in the production of TSP to make its phosphate highly water-soluble also markedly increased the solubility Cd. Reducing Cd content of TSP by using phosphate rock low in Cd in the manufacturing TSP is essential if reduction of the transfer of Cd from TSP to crops and then to humans through the consumption of the contaminated crops is to be accomplished. Where soils had already accumulated high amounts of Cd, liming to bring their pH values to near neutral was an effective approach to reduce the transfer of Cd from soils to plants. While the availability of Pb and As in trace element fertilizers to lettuce was rather low, the plant could still accumulate more Pb and As as more Pb and As from the fertilizers were added with increasing rates of fertilizer application. Increased transfer of Pb and As from the fertilizers to humans is probable if the trace element fertilizers are continuously used over time for crop production. The risk if occurred is expected to be low largely because of their low bioavailability. Liming had minimal effect on the availability of Pb and As in soils. Thus, for the soils contaminated with Cd, Pb and As, liming could still be considered an effective remediation approach as it reduced the total transfer of the metals from soils to crops. The ultimate solution to the soils contaminated with these metals relies on effective removal of the metals via chemical and/or biological extraction. Phytoremediation or phytoextraction with hyperaccumulator, Pteris vittata, in the coastal Pacific Northwest, however, was found not as effective as reported elsewhere even for As. This coupled with rather low over-winter survival rate of the plant in this region with predominantly cool environment made phytoextraction of soil As with this brake fern infeasible. Removal of soil Pb and Cd by washing with dilute EDTA solution was successful. To minimize the amount of soil to be washed and volume of wastewater generated in a contaminated area, subsoil irrigation technique could be adopted. This irrigation technique by injection of the chelate solution into the subsoil could solubilize Pb and Cd and the chelated metals moved with soil solution upward to the surface layers by evaportranspiration. With reduced amount of the contaminated soil to be extracted, less wastewater was produced. The technique, however, was found ineffective for soil As. Further study is needed to identify the type of chelate capable of solubilizing all three metals in soil.
Publications
- Kuo, S., and R. Bembenek. 2008. Chromate sorption and desorption by Fe or Al oxide impregnated wood shavings. Bioresources Technol. 99:5617-5625.
- Kuo, S., B. Huang, and R. Bembenek. 2007. Release of cadmium from a triple superphosphate and a phosphate rock in soil. Soil Sci. 172:257-265.
- Kuo, S., M.S. Lai, and C.W. Lin. 2006. Influence of solution acidity and CaCl2 concentration on the removal of heavy metals from metal-contaminated rice soil. Environ. Pollu. 144:918-925.
- Huang, B., S. Kuo, and R. Bembenek. 2004. The availability of cadmium in some phosphorus fertilizers to field grown lettuce. Water, Air, Soil Poll. 158: 37-51.
- Kuo, S., B. Huang, and R. Bembenek. 2004. The availability to lettuce of zinc and cadmium in a zinc fertilizer. Soil Science. 169:363-373.
- Kuo, S., N. Peck, B. Huang, and R. Bembenek. 2006. Soil arsenic and arsenic phytoextraction by hyperaccumulator. International Symposium on Construction wetlands and phytoremediation ecotechnology. Kao-Hsiung, Taiwan pp. 151-190.
- Huang, B., S. Kuo, and R. Bembenek. 2005. Availability to lettuce of arsenic and lead from trace element fertilizers in soil. Water, Air, Soil Poll. 164:223-234.
|
Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Although the practice of adding Fe or Al salt directly into eutrophicated water does significantly reduce P concentration in water and improve water quality, it does not promote P recycling, and increases internal P loading from sediment back into the eutrophicated water. To facilitate P recycling, we examined the possibility of using wood shavings impregnated with Fe or Al oxide as a sink for dissolved PO4, followed by retrieving it with dilute NaOH solution. It was found that as with other oxyanions, phosphate was rapidly sorbed by the shavings impregnated with either Fe or with Al oxide. The P removal rate was slightly faster for the shavings impregnated with Al oxide than with Fe oxide, and the sorption rate could be all well described by the pseudo-second-order equation. The sorbed P could be easily desorbed in 0.1 M NaOH, and the rapid desorption rate could also be well described by the pseudo-second-order equation. Ageing of sorbed P up to 9 weeks had minimal influence on the desorption, which indicated that the sorbed P did not undergo recrystallization during the ageing period, and the recovery of sorbed P will not be interfered by the prolonged use of the shavings in water treatment. The applicability of the technique to a large body of eutrophicated water including stream or lake remains to be tested. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Based on the results, shavings can be transformed into a useful product following their impregnation with Fe or Al oxide. The particular treatment is advantageous over the conventional precipitation treatment as it facilitates the recovery of phosphate and minimizes the volume of sediment, which has to be disposed of by land.
Publications
- No publications reported this period
|
Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: In metal-contaminated soils, reducing the affected soil volume would reduce the cost of remediation. We examined the efficiency of several plant species (B. kaber, B. juncea, B. napus, D. purpurea and F. arundinacea) and application of dilute EDTA/oxalate (1.0 mM) to mobilize Cd and Pb upward in a soil enriched with 3 mg Cd kg-1 and 150 mg Pb kg-1 under greenhouse conditions. The chelate solution, delivered to the bottom of the soil column, was also used as the main source of moisture to the plants. The result showed that all species accumulated less than 0.8% of Cd added and less than 0.1% of Pb added in the aerial plant parts. With the exception of D. purpurea and B. kaber all other plant species were more effective than treatment of the chelate solution alone in mobilizing Cd and Pb upward to the surface layer. Of the total Cd added less than 2% remained at the bottom of the column (12 to 14 cm), whereas greater than 50% of the Cd added was transported to the surface layer (0 to 2 cm). Of the total Pb added less than 3% remained in the bottom layer, whereas greater than 35% of the added Pb was accumulated in the surface layer in the soil cropped to B. juncea, B. napus, and F. arundinacea. As the correlation of the concentrations of Cd and Pb accumulated in the surface layer and plant dry matter yield was high, growth vigorousness of the plants had important bearing on the extent of upward mobilization of the metals. To remove toxic contaminants from water or waste water, we examined the potential of wood shavings impreganted with Fe or Al oxide. Hydrous iron and aluminum oxides are known to be capable of sorbing arsenate from solution. If hydrous Fe or Al oxide impregnated in wood shavings is capable of sorbing arsenate [As(V)], the wood waste could be used as a low cost carrier of Fe and Al oxide to remove As(V) from contaminated water. The amount of hydrous Fe or Al oxide impregnated averaged 2160 micromole Fe and 1980 micromole Al per g of poplar (Populus deltoides) wood shavings, and the impregnated Fe or Al oxide was highly reactive with As(V). Of the added As(V) added up to 133.5 micromole, the average of 97.1% and 96.8% were sorbed by the Fe oxide and Al oxide impregnated shavings, respectively, at 21 plus or minus 2 degrees C. The rate of As(V) sorption by the Fe or Al oxide impregnated shavings was rapid and could be well described by the pseudo second order equation. The sorbed As on Al oxide shaving could be rapidly and completely desorbed by 0.1 M NaOH, and the desorption behavior was unaffected by ageing up to 9 weeks. While desorption of sorbed As on Fe oxide shavings in 0.1 M NaOH was also rapid, ageing slightly depressed the desorbaility of sorbed As. The result indicated that the dilute alkaline solution could be utilized to displace all or most of sorbed As before the used shavings are disposed of. The utility of the Fe or Al oxide shavings as a continuous sink for As(V) was substantiated by the removal of most ,if not all, of As(V) added over 14 sorption cycles. The results from the study substantiates the utility of the shavings as a carrier for Fe or Al oxide to remove As(V) from contaminated water. TARGET AUDIENCES: Scientists, researchers in various institutions including state environmental protection agencies, and graduate students
Impacts
The product developed a low cost means to remove dissolved arsenic from groundwater and contaminated water. The technique also provides a means to retrieve the retained arsenic from the shavings to prevent secondary contamination from disposal of the used shavings. The soil remediation technique will provide a new technique to reduce the volume of contaminated soils so that the cost of remediation can be drastically reduced.
Publications
- No publications reported this period
|
Progress 01/01/06 to 12/31/06
Outputs
Phytoremediation of metal-contaminated soils has not been proven effective in reducing metal contents in most metal-contaminated soils to safe levels within a reasonable time span. This is particularly true under field conditions. This study was intended to develop a biologically mediated chemical approach to facilitate remediation of metal-contaminated soils. Canola, annual or perennial ryegrass, or fescue was planted to a sandy loam soil containing elevated amounts of cadmium and lead. Solution containing dilute oxalic acid (Ox) and ethylenediaminetetraacetic acid (EDTA) (1.0 mM) was delivered to the bottom of the soil to provide water to the plants and to enhance upward mobilization of the metals. The results showed that most of soil cadmium and lead moved upward and accumulated in the surface layer (0-5 cm) with the treatment when the soil was planted to the Brassica or annual or perennial grass. This greatly reduces the volume of the soil that has to be disposed
of. The effect was limited, however, if the solution was replaced with water or if none of the plants was growing in the soil. The volume of the solution needed to maintain the field capacity of the soil was greatly reduced if none of the plants was grown in the soil to enhance the evaporation loss of soil water. Research including other grass species is being initiated to determine if these grass species could be more tolerant of the chelate and organic acid and further enhance transpiration loss of soil water to accelerate upward mobilization of the metals and reduce time required for successful remediation.
Impacts
This biologically mediated chemical approach could potentially emerge as a new technique for remediating soils contaminated with such toxic metals as cadmium and lead. With phytoremediation largely failing to remediate metal-contaminated, development of a new and effective technique is highly desirable.
Publications
- Kuo, S. 2006. Influence of solution acidity and CaCl2 concentration on the removal of heavy metals from metal-contaminated soils. Environmental Pollution. 144:918-925.
|
Progress 01/01/05 to 12/31/05
Outputs
To determine which Cd fraction(s) in the phosphorus fertilizers is responsible for the increase with time of available Cd in the soil receiving phosphorus fertilizers, the phosphorus fertilizers, including triple superphosphate and rock phosphate, contaminated with elevated amounts of Cd were sequentially extracted with H2O and 1 M HCl. The extractions partitioned the Cd in the fertilizers into readily labile, moderately labile, and residual non-labile forms. The results show that solubility of Cd, Zn, or P in the PR was very low in water as should be expected given the extremely low solubility of PR particularly in the neutral or near neutral condition. High stability of PR Cd is reflected by <0.1% of the total Cd in the readily labile form (water-soluble), 30% in the moderately labile form (1 M HCl soluble), and 69% in the highly stable residual form. Acidulation of the PR increased the readily labile Cd to 35%, Zn to 67%, and P to 79%. It also enlarged the
moderately labile Cd fraction to 58%. The moderately labile Cd appeared to control the rate of the release of Cd from the TSP or PR applied to the soil. Acidulation of PR for the production of TSP enlarged the pool sizes of Cd and Zn and promoted their solubility in soil. The Fe- or Al- impregnated wood chip had remarkable capability to sorb chromate and phosphate. The rate of the retention of chromate and phosphate for the Al-impregnated wood chip was considerably faster than for the Fe-impregnated wood chip. It is unclear at this time if the activation energy required for the formation surface complexes of Al and the oxyanions was lower compared to that for the formation of surface complex of Fe and the oxyanions. As with the rate of sorption of the oxyanions, the rate of desorption of the sorbed oxyanions was rapid in the dilute NaOH solution. Whereas desorption of the sorbed oxyanions by NaOH involved a dissolution process for the Al-impregnated wood chip system, it was mainly an
anion exchange for the Fe-impregnated system as dissolution of Fe was negligible in the dilute NaOH. The accelerated stabilization of the sorbed Cr in the Fe- than in the Al-impregnated wood chip signaled a part of the sorbed Cr(V) on the impregnated Fe hydroxide could have been reduced to Cr(III).
Impacts
With P and Zn being far more soluble in water than Cd in the TSP, a strategy could be developed to reduce Cd input into agricultural soils from P fertilization. It involves dissolving the TSP in water first so that the small water-insoluble fraction containing most of Cd in the TSP could be removed from solution. The solution containing most of P and Zn in the TSP can be applied to field for crop production. This practice could reduce Cd input into soil without affecting the efficiency of P use. With the high capacity of Fe- and Al-impregnated wood chip to sorb oxyanions, wood chip can be converted into a product for removing contaminants from wastewater and/or storm and surface runoffs to protect the quality of surface and ground waters.
Publications
- Huang, B., S. Kuo, and R. Bembenek. 2005. Availability to lettuce of arsenic and lead from trace element fertilizers in soil. Water, Air, and Soil Pollution. 164:223-239.
|
Progress 01/01/04 to 12/31/04
Outputs
Some waste-derived trace element fertilizers may contain elevated amounts of arsenic (As) and/or lead (Pb), and the impact of their use on As and P accumulation in soil and uptake by plants should be investigated. This greenhouse study examined how increasing rates of an iron (IR) fertilizer, containing 4806 mg kg-1 of As, and a granulated zinc fertilizer (G-Zn), containing 18080 mg kg-1 of Pb, and liming affected As and Pb availability in a silt loam soil and uptake by lettuce (Lactuca sativa L.). Treatments of the soil with As as As2O3 and Pb as PbCl2 were included for comparison. Soil total and NaHCO3-extractable As increased with increasing inputs of As regardless of As source. This was true also for soil total and DTPA- extractable Pb except that Pb source had a significant effect on soil DTPA-Pb. Sufficient oxidation arsenopyrite (FeAsS) in the IR could have occurred, resulting in 36.4% of total As in IR extractable by NaHCO3. Only an extremely small fractions
of the added As from IR (5x10-3 %) and of the added Pb from G-Zn (7x10-3 %) were accumulated in the plant. Source had an effect on As accumulation, but not on Pb accumulation, by lettuce. The less accumulation of As from IR than from As2O3 by the plant could be attributed to a high molar ratio of Fe to As (419) in readily labile As fraction to render As in IR less available than As in As2O3. The molar ratio of Fe to Pb in the readily labile fraction of Pb in G-Zn was zero, which limited the influence of Fe on the accumulation of Pb from G-Zn despite an extremely high total Fe (18.3%) in this waste-derived fertilizer. The transfer coefficients (Tc) of the added As (0.013) and Pb (0.014) over all sources and lime rates were very low. Since nearly all of As and Pb added from the fertilizers remained in the soil, how continuous uses of the products over time on As and Pb accumulation in the soil and uptake by the plant remains to be studied.
Impacts
Lead and As contaminants in trace element fertilizers can be available to plants even though the availability is rather low. Because of matrix effect, the total amount of Pb and As in the fertilizers should not be used as an indicator of their availability to plants.
Publications
- Huang, B., S. Kuo, and R. Bembenek. 2004. The availability of cadmium in some phosphorus fertilizers to field-grown lettuce. Water, Air, Soil Poll. 158:37-51.
- Kuo. S., B. Huang, and R. Bembenek. 2004. The availability to lettuce of zinc and cadmium in a zinc fertilizer. Soil Science 169:363-373.
|
Progress 01/01/03 to 12/31/03
Outputs
Soil washing is one of the techniques used in the remediation of metal contaminated soils. Inappropriate use of chemicals could lead to destruction of soil physical and chemical properties and tremendous loss of nutrients in the soil. Hydrochloric acid is one acid that is recommended for soil washing in other nations. We examined how concentration of the acid affects the efficacy of such heavy metals as cadmium being removed from the soil contaminated with elevated amounts of Cd. At concentration 0.05 M or higher, HCl extracted about 68% of the total Cd from a Cd-contaminated Ho-Mei soil in central Taiwan. However, a simultaneous extraction of a large quantity of Fe and Al from the soil signaled a destruction of soil physical and chemical properties resulting from the extraction. The use of moderately high concentration of the acid to remediate Cd contaminated soil is unwise. The acidified 0.01 M CaCl2 with HCl to 0.01 M was as effective as the high concentration of
HCl to extract Cd from the soil without causing a substantial dissolution of Al and Fe in the soil. This extracting solution was comparable with, or even slightly better than, 0.001 M EDTA in extracting Cd from the soil. As the acid concentration was lowered to below 0.01 M, the concentration of CaCl2 had to be raised to levels well above 0.01 M for the extraction to maintain the same effectiveness. EDTA was superior to acidified CaCl2 or citric acid in removing Pb from the soil. This is reasonable given the stability of Pb-EDTA complex. The same stability, however, prevents EDTA from being used for soil remediation purpose under the open system in natural environments unless measures are put into place to fully collect the complex. Without doing so, the complex could accelerate the transport of Pb to ground water.
Impacts
The result offers an alternative soil washing method for remediation of cadmium-contaminated soils. The method is effective in removing Cd from the soils without causing significant deterioration of their physical and chemical properties.
Publications
- Huang, B., S. Kuo, and R. Bembeneck. 2003. Cadmium and zinc in some phosphorus and trace element fertilizers and availability to leaf lettuce. Water, Air and Soil Poll 147:109-127
- Huang, B., S. Kuo, and R. Bembenek. 2003. Cadmium uptake by cucumber from soil amended with phosphorus fertilizers. J. Am. Soc. Hort. Sci. 128(4) 615-620.
|
Progress 01/01/02 to 12/31/02
Outputs
The primary objective of this study was to determine the rate of the release of Cd from a triple superphosphate (TSP) (19.6%P) and a western phosphate rock (PR) (14.6%P) which contained 127 and 40 mg Cd kg-1 and 1460 and 375 mg Zn kg-1, respectively. Of the total Cd in the TSP 34.1% was water-soluble and 55.3% dilute acid-soluble, which were much higher compared to the amount of Cd in water-soluble (0.0013%) and in dilute-acid soluble (29.8%) forms in the PR. The low solubility of Cd in the PR was also reflected by close to 70.1% of the total Cd soluble only in concentrated acid. While the water-soluble fraction of Zn in the PR was very low (0.006%) as compared to TSP (50.7%), the dilute acid-soluble Zn in the PR was rather high (71.3% as opposed to 45.5% in the TSP). The low solubility of Cd and Zn in the PR than in the TSP is to be expected as, in the production of TSP, phosphoric acid is added to PR to enrich P and increase P solubility. The initial amounts of Cd
and Zn extractable by DTPA in the soil treated with TSP averaged 35.1 and 45.3 % of the total amounts of Cd and Zn added, respectively, which were close to the amounts of Cd (34.1%) and Zn (50.7%) the TSP had in the water soluble fractions. Given the very small amount of Cd the PR had in the water-soluble fraction (0.0013%), the small amount of Cd added extractable by DTPA (6.7%) is not surprising. Despite the amount of Zn in the water-soluble fraction in the PR being equally small (0.006%), a high percentage of added Zn in the PR was extracted by DTPA initially (43.7%). Reaction of the PR with the soil had enhanced the extractability of Zn in the PR. The ratio of Cd to Zn in the DTPA extract for the soil treated with TSP (0.080) was essentially the same as that in the fertilizer (0.086), implying that the added Cd and Zn from TSP were equally accessible to DTPA. The ratio was much lower in the DTPA extract for the soil treated with the PR (0.015) than in the fertilizer (0.108) to
suggest a greater accessibility of its Zn to DTPA than its Cd at least initially. The amount of Cd and Zn added from TSP extracted by DTPA increased with increasing incubation time, reaching a maximum about 20 d of incubation before declining gradually at a rate depending on the amount of TSP added. A zero-order rate equation described well the amount of Cd extracted with time. The zero-order rate equation also described well the increase in the amount of Cd added from the PR extracted by DTPA with time up to 80 d. However, further increase in the incubation time beyond 80 d increased the amount of Cd extracted at a very slow rate rather than declined as was found for the soil treated with TSP, while the amount of Zn extracted by DTPA remained unchanged. The result indicates that the soil was not responsible for the decline in the amount of Cd and Zn extracted by DTPA with time. It is speculated that a recrystallization involving certain constituents in the TSP proceeded to sequester
the released Cd and Zn, thereby lowering the amount of Cd and Zn available for extraction by DTPA.
Impacts
The Cd in phosphate rock is not as unavailable as it was thought especially in acid soils. The results caution continued use of phosphate rock containing high concentrations of Cd for crop production. Although Cd in phosphate rock is not as readily available as in treble superphosphate, a large fraction of the Cd in phosphate rock can be released in acid soils. Phosphate rock containing high Cd levels should not be used continuously for crop production.
Publications
- No publications reported this period
|
Progress 01/01/01 to 12/31/01
Outputs
The availability to plants of cadmium (Cd) contaminants in fertilizers may be affected by the source and rate of Cd applied from the fertilizers as well as soil conditions that affect solubility of the fertilizers. A field study that included a western phosphate rock (PR) and triple superphosphate TSP), and a greenhouse study that included the phosphate rock and a granulated zinc fertilizer as Cd sources were initiated to determine Cd uptake by leaf lettuce. A soluble Cd salt, CdCl2, was included in both studies for comparison. Significant effects of source and application rate of Cd and liming on Cd concentration in lettuce were found in the field and greenhouse studies. Soil total Cd did not reflect well the influence of Cd source and liming on Cd accumulation by lettuce. As a result, labile Cd measured by extraction of the soil with dilute salt solution or chelate, rather than soil total Cd, is more appropriate for predicting Cd accumulation by the crop. A very low
recovery of Cd from the fertilizers (<2%) signaled that with continuous applications of the fertilizers at high rates, increased accumulation of Cd in the soil over time should be expected. How the elevation of Cd in the soil over the long term will affect the ecological health of the soil is unclear. The transfer coefficient of Cd from the fertilizers for lettuce was much higher than that used in the risk assessment of human exposure to Cd by EPA. To improve risk assessment, the transfer coefficient should be measured based on labile Cd instead of soil total Cd.
Impacts
Cadmium in phosphorus and trace element fertilizers is available to plants when added to soil. Plant accumulation of this toxic metal increases with increasing inputs of this metal from the fertilizers. Regulation that limits its input into the soil is warranted.
Publications
- Kuo, S. 2001, Availability to lettuce of cadmium contaminant in some phosphorus fertilizers. Presented at the ASA-CSSA-SSSA annual meetings, Charlotte, NC. October 21-25, 2001.
- Kuo, S. 2001. Extractability and availability of the heavy metals in some fertilizers. Presented to W-170 Technical Committee meeting, Las Vegas, NV. January 14-16, 2001.
- Kuo, S. 2001, Extractability and plant availability of cadmium and zinc in some fertilizers. Presented at the ASA-CSSA-SSSA annual meetings at Charlotte, NC. October 21-25, 2001.
- Kuo, S. 2001. Influence of metal rates and forms on lettuce growth and metal accumulation. Presented to the fertilizer advisory committee for Washington State Department of Agriculture at Moses Lake, WA. March 27, 2001.
- Kuo, S. 2001. Influence of soil, cadmium source and growing condition on cadmium transfer coefficient for leaf lettuce. Presented at the Society of Risk Assessment annual meeting, Seattle WA. December 2-5, 2001.
- Kuo, S., B. Huang, and R. Bembenek. 2001. Availability of cadmium contaminant in some phosphorus and trace element fertilizers. Agronomy Abstr. s11-kuo132826.
- Kuo, S., B. Huang, and R. Bembenek. 2001. Extractability and plant availability of cadmium and zinc in some fertilizers. Agronomy Abstr. s11-kuo133914.
- Kuo, S., B. Huang, D. Laflamme, and D. Delistraty. 2001. Influence of soil, cadmium source, and growing condition on cadmium transfer coefficient. Society Risk Assessment Abstr. p. 66.
- Kuo, S., J. B. Harsh, W. L. Pan, and R. G. Stevens. 2001. Influence of metal rates and forms on crop productivity and metal uptake in some Washington soils. 164 pp. Submitted to Washington State Department of Agriculture, Olympia, WA.
|
Progress 01/01/00 to 12/31/00
Outputs
Among the soil factors that affect the availability of metals in soil are the amount of metals and the solubility of the metal-containing materials applied to soil, soil pH, the concentration of surface reactive sites that bind metals, and crop species. This study determined the availability of Cd and Zn in some phosphate and zinc fertilizers. The results of a greenhouse and a field trials using lettuce and/or cucumber as test plants showed that as more Cd and Zn were added to the soil from the application of western phosphate rock or a zinc fertilizer, more Zn and Cd were accumulated in the soil. Increase in the accumulation of these metals in lettuce and cucumber vine and fruits had been found. Although the total Cd and Zn in the soil correlated well with the amounts of metal-contaminated fertilizers applied, they were a poor measure of the accumulation of the metals in the plants. While the prediction of the accumulation of the metals in the plant was improved with
the Diethylenetriaminepentaacetic acid (DTPA) test, it was best with dilute salt(0.05 M CaCl2)test. This is because the total Cd and Zn, and DTPA extractable Cd and Zn did not mimic the response of plant accumulation of the metals to soil pH and the solubility of the metal-containing materials as well as the dilute salt extractable Cd and Zn did. The plant uptake coefficient defined as the amount of the metals accumulated in the plant over the concentration of the metals in the soil would be less desirable for use in risk assessment if it is determined based on the total amount of the metals than if it is determined based on the amount of DTPA or dilute salt extractable Cd and Zn.
Impacts
Because of the high availability of Cd in the phosphate fertilizer manufactured using the western phosphate ores and in the zinc fertilizer, the concentration of Cd in these types of fertilizers should be limited to prevent excess accumulation of Cd in soil and in plants. Dilute salt solution, but not the total Cd concentration of Cd in soil, should be used to measure the plant Cd uptake coefficient, which is a crucial component in the risk assessment. The total Cd of soil did not reflect the unique physicochemical properties of soil that controlled the solubility and availability of the metal in soil.
Publications
- Hummel, R.L., S. Kuo, D. Winters, and E.J. Jellum. 2000. Fishwaste compost medium improves growth and quality of container-grown Marigolds and Geraniums without leaching. J. Environ. Hort. 18:93-98.
- Kuo, S., B. Huang, and R. Bembenek. 2000. Influence of some cadmium-contaminated fertilizers on cadmium concentration in soil and availability to plants. Amer. Chem. Soc. Abstr. p. 66.
- Kuo, S., P.R. Bristow, E.J. Jellum, and M. Okiro. 2000. Nitrogen mineralization of lime-stabilized fishwaste in acid soils and its effects on plant growth. J. Environ. Qual. 29:380-387
|
Progress 01/01/99 to 12/31/99
Outputs
Some phosphate and zinc fertilizers may contain elevated concentrations of Cd and other heavy metals which may affect the growth and metal accumulation in plants. This study determined the concentrations of Cd, As and Pb in a phosphate rock (PR), a triple superphosphate (TSP) manufactured from the western phosphate rock of USA and Zn and Fe fertilizers that were manufactured from the industrial waste. The respective concentrations of Cd in the PR, TSP, zinc and Fe fertilizers were 40, 127, 32, and 485 mg/kg. The Fe fertilizer also contained a high concentraiton of Pb (18,080 mg/kg). The application of these fertilizers to soil had variable effects on the accumulation of Cd, Pb, and As in soil and in lettuce or cucumber vine and fruits. At application rates of one to 8 times higher than normally recommended for crop production, the TSP and PR increased total and DTPA-extractable Cd of the soil. The Fe fertilizer increased total and NaHCO3-extractable As, and the zinc
fertilizer increased total and DTPA-extractable Pb of the soil. Of the metals only Ce was more readily available to the plant. In a field study, the bio-availability of Cd from TSP and CdCl2 was much higher than that from the PR, zinc or Fe fertilizer. Matrix and/or solubility of the fertilizers are among the important factors that should be considered in evaluating bio-availability of Cd in these fertilizers. The Cd bio-transfer factor for the fertilizers (bf), defined as the ratio of plant Cd to soil Cd, was several times higher than reported for biosolids. It would be more appropriate to use bf for fertilizers, instead of bf for biosolids, to assess the health risk from repeated applications of these fertilizers for crop production.
Impacts
(N/A)
Publications
- No publications reported this period
|
Progress 01/01/98 to 12/31/98
Outputs
This study is to determine under field and greenhouse conditions the bioavailability of Pb, Cd, and As in some phosphate fertilizers (triple superphosphate and rock phosphate) and industrial by-products (ironite and granular zinc)that have been used as soil amendments. The concentrations of metals in these products ranged from 30 to 116 mg/kg for Cd, 8.8 to 4300 mg/kg for As, and 10.3 to 3400 mg/kg for Pb. Continued applications of these products to soil at high rates for a long period of time may increase the concentration of these metals in soil. For the field study the products were applied to a Sultan silt loam at rates that ranged from 0 to 8X the Washington maximum use rates. For the greenhouse study, the rates used were considerably higher, ranging from 0 to 45X the Canadian maximum annual application rate, depending on the type of the products used. The plant accumulation of Cd, As, and/or Pb by lettuce under the greenhouse conditions, and cucumber and lettuce
under the field conditions will be determined.
Impacts
(N/A)
Publications
- No publications reported this period
|
Progress 01/01/97 to 12/31/97
Outputs
The effects of various winter cover crops on soil nitrogen availability, nitrate leaching, and the productivity of the succeeding corn crop were determined. Rye and ryegrass cover crops significantly reduced nitrate leaching but were ineffective in increasing soil nitrogen availability or the productivity of the succeeding corn crop. In contrast, hairy vetch enhanced the growth of succeeding corn but was ineffective in reducing nitrate leaching. Mixtures of hairy vetch with rye or ryegrass were moderately effective in enhancing corn growth and reducing nitrate leaching as well. Mixtures of hairy vetch with oat or triticale were also effective in increasing soil nitrogen availability and corn growth. Because of the interference of calcium and magnesium on nitrate determination, it was necessary to treat soil extracts with cation exchange resin prior to reduction of nitrate with hydrazine to increase the accuracy of nitrate determination.
Impacts
(N/A)
Publications
- Kuo, S., R.L. Hummel, E.J. Jellum, and D. Privett. 1997. Fishwaste compost effects on Rhododendron growth and nitrogen leaching and transformation. J. Environ. Qual. 26:733-739.
- Kuo, S., R.L. Hummel, E.J. Jellum, and D. Winters. 1997. Solubility and leachability of fishwaste compost phosphorus in soilless growing media. Agron. Abstr. p. 34.
- Kuo, S., U.M. Sainju, and E.J. Jellum. 1997. Winter cover cropping influence on nitrogen in soil. Soil Sci. Soc. Am. J. 61:1392-1399.
- Kuo, S., and J.B. Harsh. 1997. Physicochemical characterization of metals in soil and their plant availability, p. 75-120. In. D.C. Adriano (ed) Biogeochemistry of trace metals. Science Reviews, U.K.
|
Progress 01/01/96 to 12/30/96
Outputs
To determine the potential of fishwaste compost as a P source for soil-less growing media, the solubility and leachability of fishwaste compost P were examined. The fishwaste compost contained 3.6 g P per kg, 3.80 g Ca per kg, 2.51 g Fe per kg, and 0.64 g Al per kg compost. The fishwaste compost P was moderately soluble, with 18.1% of the total P being released to solution when equilibrated in 0.01 M NaCl for 24 h. The compost P solubility was presumed to be controlled by fluorapatite in equilibrium with fluorite. Compost P solubility in 0.01 M NaCl was similar to that predicted from the solubility of the mineral in equilibrium with fluorite. Fluorapatite is moderately soluble in weakly acidic conditions. Fractionation of compost P revealed that only a small amount of compost P was in organic and residual fractions. The resulting fractionation also showed that Fe and Al were not the primary P sink for the compost P because, despite high concentrations of Al and Fe,
the residual fraction contained only a small fraction of the total P. Based on the results, it can be concluded that fishwaste compost is an effective P source for soil-less growing media.
Impacts
(N/A)
Publications
|
Progress 01/01/95 to 12/30/95
Outputs
The quality and quantity of crop residues should be considered when attempting to improve soil productivity by the utilization of crop residues. The nitrogen (N) mineralization rate and mineralization potential in the soil amended with mixed hairy vetch and rye or annual ryegrass in varying proportions were determined in a laboratory incubation study. Because of high soluble carbohydrate and low total N concentrations in rye and annual ryegrass, increasing their proportions in the mixture invariably enhanced N immobilization within a few days after residue incorporation. The immobilization resulted in lower yields and N uptake by cereal rye used as a test crop. The potentially mineralizable N was controlled predominantly by the total N concentration in the residues. The initial potential N mineralization rate was more effective than N mineralization potential or N mineralization rate constant in predicting the yields and N uptake by cereal rye.
Impacts
(N/A)
Publications
|
Progress 01/01/94 to 12/30/94
Outputs
Fishwaste/lime materials were developed and tested under the glasshouse conditions to evaluate their quality as fertilizer and lime source for crop production. The fishwaste/lime materials were as effective as calcium carbonate in neutralizing soil acidity. The mineralization of the N in the materials was quite rapid in the soil and close to 50% of the total N added in the fishwaste material was recovered in the inorganic N fraction (nitrate -N and ammonium -N). In the bark, however, the N availability was quite low. The much higher bacteria population in the bark as compared to the soil and the virtual absence of inorganic N suggest that the availability of C in the bark is sufficient to continuously stimulate microbial uptake of most of the N mineralized from the fishwaste/lime materials. The glasshouse trials showed that the fishwaste/lime materials were high quality fertilizer and lime sources in soil for a variety of plant species tested.
Impacts
(N/A)
Publications
|
Progress 01/01/93 to 12/30/93
Outputs
This study characterized the compost organic N fraction and investigated the residual availability of compost N in soil along with the utility of compost N as a potential slow-release N fertilizer using laboratory incubation and nursery plant growth trials with different irrigation practices. Some residual N available to corn was found only in the ground fish/alder sawdust compost because fishwaste composts decomposed readily in soil under field conditions. The majority of N applied in the compost could not be accounted for in the soil or harvested plant material. The groundfish/hemlock-fir sawdust compost provided for excellent growth and quality of fast-growing marigolds and geraniums under controlled irrigation for a period of at least 6 weeks, and the 50:50 mixture of compost and bark was an excellent growing medium for both nursery stock and bedding plants. The information obtained in this study is important for the production, utilization, and marketing of
fishwaste composts and advances the knowledge of compost chemistry in soil or soilless media.
Impacts
(N/A)
Publications
|
Progress 01/01/92 to 12/30/92
Outputs
The effectiveness of fishwaste compost as a slow-release N material for several container crops including Rhododendron, Juniperii horizontalis, and Vaccinium Carymbosum was tested under field conditions. Water was applied as needed by an overhead sprinkler irrigation system. Leachate was collected and determined weekly for volume, the concentrations of N and P, as well as pH. Measurements of plant growth parameters including plant canopy height and fresh and dry weights of top growth and roots were made at the end of growing season. More than 90% of leachable inorganic N in the compost was released within the first five weeks of irrigation. This extensive leaching, coupled with a very slow N mineralization, made the compost ineffective as a slow-release N to meet the N requirements for the container crops under the overhead sprinkler irrigation system. A study is being initiated to evaluate the effectiveness of fishwaste compost as a slow-release N material using a
drip irrigation system to reduce N leaching.
Impacts
(N/A)
Publications
|
Progress 01/01/91 to 12/30/91
Outputs
The residual availability of organic N from fishwaste composts to corn was studied in a silt loam soil that contained 2.0% organic C and 0.2% organic N in the surface soil. The composts used were groundfish/alder sawdust, groundfish/hemlock-fir sawdust, shrimpwaste sludge/alder sawdust, and shrimpwaste sludge/hemlock-fir sawdust. The C:N ratios for the composts were relatively low, ranging from 18 to 24. Compost applications at 100 mT/ha were sufficient to double the soil organic C and increase soil organic N by at least 65% initially. Both total organic C and N of the compost-amended soil were only slightly higher than those of unamended, control soil one year after application. This indicates that substantial mineralization of organic C and N from the fishwaste composts occurred following their incorporation into the soil. The mechanisms for the enhanced C and N losses are not clear. All corn plants grown in the soils that received compost application a year before
showed moderate N deficiency and yielded much lower than those received 120 kg N/ha of N fertilizer.
Impacts
(N/A)
Publications
|
Progress 01/01/90 to 12/30/90
Outputs
Four seafood waste composts including groundfish/hemlock, groundfish/alder, Protan/hemlock, and Protan/alder were tested for N and P availability. The results indicate that with the exception of Protan/alder the composts contained 0.4% inorganic N and 200 to 500 mg P/kg and improved the yields of corn and grasses considerably under either greenhouse or field conditions. The alder is not a good bulking agent for composting as it immobilized considerable amounts of inorganic N. All composts had lower Zn and Cu availability than the sludge compost and there is no threat to the plant quality if applied at the recommended rate. As much as 40% of the inorganic N from the composts was not accounted for in the surface soils or in the plants. It is not certain if this results from a substantial N leaching and/or denitrification. The land disposal of groundfish compost for crop production is feasible, but repeated application on the same soil will be dictated by the availability
of the residual N of the composts.
Impacts
(N/A)
Publications
|
Progress 01/01/89 to 12/30/89
Outputs
Zinc and cadmium sorption was studied in five diverse acid soils. Within the pH range of 3.2 to 7.2, the soils had two classes of functional groups that had average acidity constants of log K(1) = 4.09 and log K(2) = 6.49, respectively. These two classes are comparable with classes II and III in acidity levels of fulvic acids. The organic fractions in the soils are important sinks for the metals particularly in the acidic environment. The total number of sorption sites was estimated based on H or OH sorption using a batch equilibrium technique. A sorption model that contained the total number of sites, solution concentration of the metals, and pH as variables accounted for close to 90% of the variability of Zn and Cd sorption among the soils at pH < 6. The variability was not accounted for as well above pH 6, suggesting increased influence of other parameter(s) at higher pH values. The (H)/(M(e)) stoichiometry was approximately 0.48 for Cd and 0.55 for Zn. The
logarithm of the conditional stability constants of the surface complex were 0.50 and 0.75 for Zn and Cd, respectively.
Impacts
(N/A)
Publications
|
Progress 01/01/87 to 12/30/87
Outputs
The residual availability of zinc (ZN0 and cadmium (Cd) to Swiss chard from the soils amended with varying rates of sludges was related to pH as well as the Zn and Cd sorption characteristics of the soils. Consequently, the quantity of the metals extracted by the conventional tests such as DTPA extraction did not actually reflect either the quantity or the activity of these two metals in the soil solution and had little or no significant correlation with Zn and Cd uptake by plants. This phenomenon has been repeatedly observed in many metal-contaminated soils. A method was developed that included the metal sorption capability and ph with DTPA-extractable Zn and Cd levels for estimating the concentration or the activity of the metals in soil solution. The approach resulted in much improvement in the explanation for the variability of Zn and Cd uptake by the plants across soil types and allowed a better estimate of the availability of metals present in soils under
various soil conditions. The estimated critical Zn and Cd concentrations that were fatal to Swiss chard were approximately 500 and 10 mg kg, respectively, based on the model results.
Impacts
(N/A)
Publications
|
Progress 01/01/86 to 12/30/86
Outputs
Zinc and cadmium sorption and desorption by five soils with diverse physical andchemical characteristics were investigated to determine which adsorption model(s) best describes their sorption behavior and which soil parameter(s) governs their release into soil solution. The sorption envelope showed that as the pH was raised to 5.5 and above, there was a sharp increase in the capability of the soils to retain Zn or Cd. The sorption data generally fit the modified Langmuir equation better than the classical Langmuir equation, which suggests that the electrostatic interaction among the sorbed metal molecules needs to be considered to better describe the sorption behavior of the two metals in soil systems. The amount of Zn or Cd desorbed by DTPA or EDTA-Ca(NO(3))(2) extractants was not entirely dependent upon theiramounts sorbed on soil particles. The extractability of Cd, for instance, decreased from 90% for sandy soils with relatively low amorphous Fe oxide content &
low Cd sorption capacity to approximately 50% for heavy-textured soils with high Fe oxide content and high Cd sorption capacity. The metal sorption capacity of the soils obviously plays an active role in the desorption of the metals by the two extractants used. The fraction of the surface saturation, defined as the amount sorbed over the sorption capacity of soils, was a more suitable soil parameter to describe the release of the two metals from the solid phase into the solution phase.
Impacts
(N/A)
Publications
|
Progress 01/01/85 to 12/30/85
Outputs
A study to determine the bio-availability and extractability of residual sludge-borne Zn, Cd, and Cu in soils was conducted. Copper was not accumulated in corn plants in any significant degree and remained tightly bonded on the surfaces of soil particles nine years since it was applied. In contrast, Zn and Cd, particularly Cd, remained readily available to the plants, especially at low soil pH levels. A large proportion of added Cd was extractable in DTPA solution, which indirectly explains its high accumulation in the plants. Apparently, no sufficient aging phenomenon took place in the soils to cause the metal to be less plant available. From a Zn and Cd sorption-desorption study, it was found that the coverage of these two elements on the surfaces of soil particles played some important role in regulating their availability across soil types at constant soil pH.
Impacts
(N/A)
Publications
|
|