1a. Objectives (from AD-416)
(1) Assess the environmental impacts of land-applying different rates of municipal biosolids on the production of forage and biofuel grasses and on water quality at Austin Water Utility's Hornsby Bend Municipal Biosolid Recycling Facility. (2) Identify and quantify the composition, concentration, and distribution of nutrients (carbon, nitrogen, phosphorus), micronutrients (trace metals), and endocrine disrupting compounds (EDCs) in biosolids, soils, waters, and plants. (3) Measure the potential mobility of nutrients, micronutrients, and EDCs in surface run-off and in water infiltrating through the soil profile using rainfall simulations in the field. (4) Use empirical field data to develop and test new model components for SWAT (phosphorus, EDCs) to further validate and improve model code. (5) Provide risk assessment to the City of Austin regarding the potential watershed impacts of Austin's municipal waste recycling program.
1b. Approach (from AD-416)
We will conduct a broad survey of the Hornsby Bend site to assess the presence and concentrations of nutrients, micronutrients, and EDCs in biosolids, soils, waters, and plants. Ten-meter-wide strips of switchgrass will be established within the existing forage production system (coastal bermudagrass) receiving Class B biosolid applications. Rainfall simulations will be conducted in forage production plots and in biofuel production plots to quantify the movement of nutrients, micronutrients, and EDCs in surface run-off and in water infiltrating the soil profile. Crop productivity and soil microbial activity will also be measured across different biosolid application rates (0, 10, 20, and 30 dry tons/acre/year).
3. Progress Report
Land application is one means of managing biosolids. Biosolids contain essential plant nutrients such as nitrogen and phosphorous, as well as important trace metals, which make them a valuable fertilizer. However, biosolids also contain many anthropogenic chemicals. Land application introduces these chemicals to the environment, allowing them to interact with water quality, soil function, wildlife, and human health. Earthworms were collected from field sites with various rates of biosolid application at Hornsby Bend Biosolids Management Plant (HBBMP) at Austin, Texas, from spring 2009 to spring 2010. Biota in on-site retention ponds were sampled; collected organisms include aquatic vegetation (algae and plants), snails, crawfish, tadpoles, aquatic insects, and one turtle. Overall, the diversity of organisms at the site appears to be limited and sampling conditions are challenging. Texas Parks and Wildlife Department Environmental Contaminants Laboratory and Contaminants Assessment Team has prepared all sample tissues for evaluation of presence of selected pharmaceuticals and personal care products (PPCPs) in the biota from the site. Preliminary results show earthworm accumulation of compounds. Preliminary data have been presented at a professional meeting (Hamlett, P, Arnold JG, Johnson MVV, Jin VL (5/2010) Synthetic organic chemicals in earthworms from agricultural soil amended with municipal biosolids. 58th American Society for Mass Spectrometry Conference on Mass Spectrometry, Salt Lake City, UT) Soil cores were sampled at field sites with various rates of biosolid application at HBBMP in mid-March 2009. These samples have been subdivided and processed in numerous experiments. Manuscripts are in preparation for microbial respiration analyses and biologically available metals accumulation analyses. Data were presented at a professional meeting (Jin VL, Witherington EM, Johnson MVV, Haney RL, Arnold JG (5/2010) Impacts of land-applying Class B municipal biosolids on soil microbial activity and soil nutrient and metal concentrations. Water Environment Federation: Residuals and Biosolids 2010. Savannah, GA). Soil cores were subsampled for analyses of anthropogenic compounds, including hormone mimics and personal care products. The USGS lab in Denver is still in possession of these samples. Most have been analyzed and are undergoing quality control checks. A second set of subsamples was sent to ECL in San Marcos; they have been analyzed for total metals content. We are currently analyzing the results in preparation of writing manuscripts. Model validation cores were collected in Nolanville, Texas, in June 2010. These cores are currently being processed in our laboratory to be sent to USGS for further analyses. New collaborators were identified. Soils analyzed by USGS for anthropogenic compounds will also be analyzed by two other laboratories, for Quaternary Ammonium Compound and for Nanoparticle quantification as affected by biosolid amendment histories.