Progress 10/01/05 to 09/30/08
Outputs
OUTPUTS: Through workshops, conferences, consultation and media contacts, a wide stakeholder audience was reached on the subject of sewage sludge (biosolids) application to farmlands. Consultation on national projects allowed us to influence research conducted on health-implications of land application of sewage sludges, on the development of a protocol for local investigations, on USEPA research on methods to assess soil and air impacts of land application, on cost-benefit assessment of disposal alternatives and on multi-faceted research in Ohio. Consultation assisted more than 20 communities in evaluating sludge management options. Trainings and workshops reached more than 100 wastewater professionals and many citizens. Through a collaborative effort led by Cornell, scientists from universities in the northeastern United States developed and published guidance on sludge use including recommendations to protect soil quality and productivity. Collaborations were formed with researchers to enhance Cornell bioassay research with chemical measurements performed by USGS and Colorado State University. Groups were convened to discuss the meaning of soil test results and of how different soil test methods reflect potential impacts on environmental and human health. Laboratories in the northeast use different methods for metals such as lead, zinc and cadmium, making interpretation across states difficult. Most soil tests presently in use do not reflect bioavailability to crops or to soil invertebrates. These discussions led to development of a research proposal, which has now been funded, and will result in more relevant soil test methods as well as guidance materials to help people interpret test results. Bioassay methods provide a way to assess the impacts of complex mixtures such as sewage sludge. Earthworms are one of several model organisms useful for toxicity assays because of their responsiveness to soil contaminants due to high soil ingestion rates. To gain insight into the effect of sewage sludges on soil-living organisms, we conducted short-term lab bioassays with soil samples amended with different sludge concentrations and aged for different lengths of time. These assays of aged, soil/sludge mixtures included a germination study with Lactuca sativa (lettuce) seeds as well as fatality and reproductive tests using Eisenia fetida (earthworms). Heavy metals can affect microbial processes in soils that are critical to soil health, such as organic matter and pesticide decomposition. As part of a series of bioassays testing the impact of heavy metal contamination on plant growth and microbial functions, we measured urease enzyme activity as well as degradation rates of the commonly used herbicide, glyphosate (Roundup), in variably Zn and Cu-contaminated soils. The results confirmed that certain critical levels of Zn and Cu in soils resulted in reduced urease function as well as reduced ability to decompose glyphosate. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Organic residuals such as sewage sludges are widely used in agriculture as sources of nutrients. However, they contain contaminants that may affect soil quality, impact soil processes, move to groundwater and surface water,or be taken up by plant. Answering questions about these processes that could degrade soil health is critical to enable stakeholders to make sound choices about residual use. Plant and earthworm bioassay conducted suring this project showed that sludge amendment of soils at several percent by weight could detrimentally affect seed germination and earthworm survival and reproduction. Interestingly, sludge-amended soils aged for 8 weeks had a more pronounced effect on reproduction than un-aged control soils. Despite including procedures to equalize pH, we observed a drift to lower pH at higher sludge concentrations, which may or may not have influenced these reproduction results. The failure to explain these effects on earthworms based on the known levels of metal contaminants in the sludge indicates a need to study the toxic effects of other sludge chemical contaminants. Incubation of Cu and Zn-contaminated soils (2 soil types, fine and coarse-textured) containing C14-labeled glyphosate (Roundup) was conducted with continuous monitoring of carbon dioxide release from the soil. The highest Cu treatment (400 mg per kg) caused substantial reduction in the rate of glyphosate degradation in the coarse-textured soil, but not in the fine-textured soil. Lower levels of Cu (less than or equal 200 mg per kg), and all levels of Zn tested (100-400 mg per kg) had only small effects on degradation rates. However, Zn had an antagonistic effect on Cu; high soil Zn reduced the impact of soil Cu in inhibiting glyphosate degradation. The results showed Cu to be more toxic than Zn to microbial processes of glyphosate degradation, with coarse-textured soil being more sensitive to these inhibitory metal effects than fine-textured soils. The soil urease enzyme assays similarly indicated that soil Zn and Cu in the concentration range of 200-400 mg kg have detrimental effects on soil microbiological function, but the severity of these effects again vary depending on soil texture. The results point to the need for site and soil-specific recommendations for toxic metal concentration limits in soils, indicating that existing federal regulations on sludge application do not protect all soil types from harmful effects of metals.
Publications
- Kim, B., M.B. McBride and A.G. Hay. 2008. Urease activity in aged copper and zinc-spiked soils: relationship to CaCl2 extractable metals and Cu activity. Environmental Toxicology and Chemistry 27, 2469-2475.
- Hua , L. , W.X. Wu, Y.X. Liu, Y.X. Chen and M.B. McBride. 2008. Effect of composting on polycyclic aromatic hydrocarbons removal in sewage sludge. Water Air and Soil Pollution 193, 259-267.
- Hua , L. , Y.L. Wang, W.X. Wu, M.B. McBride and Y.X. Chen. 2008. Biomass and Cu and Zn uptake of two turfgrass species grown in sludge compost-soil mixtures. Water Air and Soil Pollution 188, 224-234.
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: Through workshops, conferences, consultation and media contacts, a wide audience was reached. Consultation on national projects allowed us to influence research conducted on health-implications of land application of sewage sludges (aka biosolids), on the development of a protocol for local investigations, on USEPA research on methods to assess soil and air impacts of land application, on cost-benefit assessment of disposal alternatives and on multi-faceted research in Ohio. Consultation assisted more than 20 communities in evaluating sludge management options. Expert knowledge was provided to over 40 journalists across the US. Trainings and workshops reached more than 100 wastewater professionals and 75 citizens. Groups were convened to discuss the meaning of chemical test results and of how different chemical test methods reflect potential impacts on environmental and human health. Laboratories in the northeast use different methods, making interpretation across states
difficult. Most tests do not reflect bioavailability. These discussions led to development of a research proposal and will result in guidance materials to help people interpret test results. Through a collaborative effort led by Cornell, scientists from universities in the northeastern United States developed and published guidance on sludge use including recommendations to protect soil quality and productivity. Collaborations were formed with researchers to enhance Cornell bioassay research with chemical measurements performed by USGS and Colorado State University. Understanding of the importance of colloidal transport of contaminants through soils and into groundwater was increased by research and publication of an article in a practitioner-oriented journal. Bioassay methods provide a way to assess the impacts of complex mixtures such as sewage sludge. Earthworms, one of several model organisms useful for toxicity assays, are ideal because they have a high tolerance to changes in
temperature, moisture and acidity. Furthermore, their responsiveness to soil contaminants due to high soil ingestion rates provides strong correlations between laboratory and field studies on terrestrial biota. To gain insight into the effect of sewage sludges on soil-living organisms, we conducted short-term lab bioassays with soil samples amended with different sludge concentrations and aged for different lengths of time. These assays of aged, soil/sludge mixtures included a germination study with Lactuca sativa (lettuce) seeds as well as fatality and reproductive tests using Eisenia fetida (earthworms). We conducted inductively coupled plasma mass spectrometry (ICP-MS) metals analysis on CaCl2 extracts of the soil samples looking at copper and zinc levels. Heavy metals can affect microbial processes in soils that are critical to soil health, such as organic matter and pesticide decomposition. As part of a series of bioassays testing the impact of heavy metal contamination on plant
growth and microbial functions, we measured degradation of the commonly used herbicide, glyphosate (Roundup), in variably Zn and Cu-contaminated soils, testing the hypothesis that decomposition would be inhibited.
PARTICIPANTS: Ellen Z. Harrison, Cornell Waste Management Institute, Dept of Crop and Soil Sciences, Cornell University. Anthony Hay, Dept of Microbiology, Cornell University. Murray B. McBride, Dept of Crop and Soil Sciences, Cornell University. Tammo S. Steenhuis, Biological and Environmental Engineering, Cornell University.
TARGET AUDIENCES: Farmers, agricultural advisors, governmental agencies at local, state and national level, researchers, and journalists are the primary audiences.
Impacts
Organic residuals such as sewage sludges (aka biosolids) are widely used in agriculture. In addition to nutrients and organic matter these residuals contain chemical and biologic contaminants that may affect soil quality, impact soil processes, move to groundwater and surface water, be taken up by plants, or degrade in the environment. Answering questions about these processes is critical to enable stakeholders to make sound choices about residual use. Plant bioassay results showed that while lettuce germination rates were not different between unaged and aged sludge-amended soils, increasing concentrations of sludge showed a decrease in germination. Results of 25 percent germination at 4 percent sludge concentrations vs 100 percent germination in control soil indicate a level of toxicity that is significant. Earthworm survival rates were 100 percent for all concentrations/ages except one. Only 20 percent of the earthworms survived in the jars from the mixture
containing the highest concentration of sludge (4 percent) that had aged for 8 weeks. This is statistically significant from all other concentrations/ages, with a p-value less than 0.004. Some aestivation, a curling behavior that indicates stress, while not quantitative, was observed sporadically at the slightly lower sludge concentration of both unaged and 8-week aged sludged-soils. Reproduction assay results demonstrate that increased concentrations of sludge also had a corresponding detrimental effect on E fetida reproduction and suggest that sludge-amended soil, aged for 8 weeks, had a more pronounced effect on reproduction than unaged control. However, despite including procedures to equalize pH, we still observed a drift to lower pH at higher sludge concentrations, which may or may not have influenced these reproduction results. ICP metals analysis did not lend any insights into a correlation between copper and zinc levels and toxicity associated with sludge, aged or not. An
80-day incubation of Cu and Zn-contaminated soils (2 soil types, fine and coarse-textured) containing 14 C-labeled glyphosate (Roundup) was conducted with continuous monitoring of 14 CO2 release from the soil. The highest Cu treatment (400 mg/kg) caused substantial reduction in the rate of glyphosate degradation in the coarse-textured soil, but not in the fine-textured soil. Lower levels of Cu (less than or equal 200 mg/kg), and all levels of Zn tested (100-400 mg/kg) had only small effects on degradation rates. However, Zn had an antagonistic effect on Cu; high soil Zn reduced the impact of soil Cu in inhibiting glyphosate degradation. The results indicate that the glyphosate degradation assay is less sensitive to soil Cu and Zn than the urease assay, reported on last year. The soil microbial bioassays indicate that soil Zn and Cu in the concentration range of 200-400 mg kg have an array of detrimental effects, but the severity of these effects vary by soil type. The results are
supportive of site and soil-specific recommendations for toxic metal concentration limits in soils, and indicate that existing federal regulations on sludge application do not protect all soil types from harmful effects of metals.
Publications
- Barrett, K.A. and McBride, M.B. (2007). Phosphate and glyphosate mobility in soil columns amended with Roundup, Soil Science, 172:17-26.
- Kim, B., McBride, M.B., Richards, B.K., and Steenhuis, T.S. (2007). The long-term effect of sludge application on Cu, Zn and Mo behavior in soils and accumulation in soybean seeds, Plant and Soil, 299:227-236. DOI: 10.1007/s11104-007-9377-3
- Harrison, E.Z and Krogmann, U. (editors), Barker, A., Harrison, E.Z., Hay, A., Krogmann, U., McBride, M., McDowell, M., Richards, B., Steenhuis, T., and Stehouwer, R. (coauthors). 2007. Guidelines For Application Of Sewage Biosolids To Agricultural Lands In The Northeastern U.S. Report of Northeast Regional Multi-State Research Committee NEC 1001. Published as Rutgers NJAES Cooperative Extension Publ. E317. Available on-line at: http://hdl.handle.net/1813/7934
- Richards, B.K., McCarthy, J.F., Steenhuis, T.S., Hay, A.G., Zevi, Y., and Dathe, A. (2007). Colloidal transport: the facilitated movement of contaminants into groundwater, Journal of Soil & Water Conservation, 62(3):55A-56A.
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Progress 01/01/06 to 12/31/06
Outputs
Organic chemicals in sewage sludges. Data on the concentration of organic chemicals in sludges were collected from the peer-reviewed literature and official reports. Data were found for 516 organic compounds grouped into 15 classes. Concentrations were compared to EPA risk-based soil screening limits (SSLs). For 6 of the 15 classes, there were no SSLs. For the 79 reported chemicals that had SSLs, the maximum reported concentration of 86 percent exceeded the SSL. Eighty-three percent of the 516 chemicals were not on the EPA established list of priority pollutants and 80 percent were not on the EPA's list of target compounds. Thus analyses targeting these lists will detect only a small fraction of the organic chemicals in sludges. A collaboration with USGS to examine bioaccumulation of pharmaceuticals in sludge-exposed earthworms has been initiated. The biodegradation of pharmaceutical products found in sludges was investigated. Genes encoding enzymes for ibuprofen,
deet, and octylphenols have been identified. The role of colloids in the transport of metals though soils. To investigate the role of colloids on the transport of metals in the subsoil we attached Cd ions to Na and Ca Montmorillonite clays and used synchrotron X rays to compare the movement of the Cd adsorbed on the clays and in solution. By measuring the fluorescence and attenuation of the X rays we obtained simultaneous in situ water saturations and Cd concentrations on time scales of tens of seconds. We studied the transport of colloids through a preferential flow path in uniform well-sorted sand. This flow path had both saturated and unsaturated zones that travel downward with time. Cd adsorbed to Na Montmorillonite clay showed little retention in the sand, while the Cd on the Ca Montmorillonite clay colloids and in solution were retarded with respect to the wetting front. The advantages and limitations of this X-ray fluorescence technique and the implications for Cd transport
were evaluated. Urease and related assays for determining toxic metal effects on soil microbial function. Heavy metals are well known to affect microbial processes in soils that are critical to soil health, such as organic matter decomposition, but assays for a number of these processes often give inconsistent results in variously metal-contaminated soils. The urease bioassay, which measures the decomposition of urea to ammonia in a short time period, was found to be stable and consistent. Initial experiments showing that well-aged Cu and Zn-contaminated soils have depressed urease activity have been completed. Soil Cu concentration had the largest effect on urease activity, with the effect of Zn being weaker. Initial results using glycine as the substrate show much the same trends, again with Cu being the most detrimental to enzyme function. Stakeholder involvement. Working with the Water Environment Research Foundation, we have participated with a diverse group of stakeholders to
develop an RFP for a project to develop a protocol to investigate reported health complaints. A team of researchers has been selected and work has commenced on protocol development.
Impacts
Organic residuals, such as sewage sludges (aka biosolids) are widely used in agriculture to improve soil quality and add nutrients. In addition to nutrients and organic matter, these residuals contain chemical and biologic contaminants that may have an impact on soil and water quality. Some of these contaminants may affect soil quality, impact soil microbial processes, move to groundwater, runoff in surface water, be taken up by plants, or degrade in the environment. Answering questions about these processes is critical to enable stakeholders to make sound choices about residual use. Farmers and their advisors, site neighbors, local, state and federal government officials are key stakeholders to reach with research-based knowledge. Researchers and policy makers obtained information on organic chemicals in sewage sludges and on the movement of contaminants retained on colloids, allowing them to design future research and to consider policy implications and options.
Publications
- DiCarlo, D.A., Zevi, Y., Dathe, A., Giri, S., Gao, B. and Steenhuis, T.S. 2006. In situ measurements of colloid transport and retention using synchrotron X-ray fluorescence. Water Resources Research. 42(12): Art. No. W12S05.
- Harrison, E.Z. 2006. Cornell Waste Management Institute. 2006. Home Garden Use of Milorganite. Cornell Waste Management Institue. Ithaca. 2 p. (http://cwmi.css.cornell.edu/milorganite.pdf).
- Harrison, E.Z., Oakes, S.R., Hysell, M. and Hay, A.G. 2006. Organic chemicals in sewage sludges. Science of the Total Envir. 367:481-497.
- Kim, B. and McBride, M.B. 2006. A test of sequential extractions for determining metal speciation in sewage sludge-amended soils. Environmental Pollution. 144:475-482.
- McBride, M.B. 2007. Attenuation of metal toxicity in soils by biological processes. In: R. Hamon, M. McLaughlin and E. Lombi (eds.). Natural Attenuation of Trace Element Availability in Soils. CRC Press, Boca Raton. 113-114.
- McBride M.B., Barrett, K.A., Kim, B. and Hale, B. 2006. Cadmium sorption in soils 25 years after amendment with sewage sludge. Soil Science. 171(1):21-28.
- Rivera-Cancel, G. and Hay, A.G. 2007. Bacterial degradation of DEET: cloning and heterologous expression of DEET hydroxylase. In press. Applied and Environmental Microbiology.
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