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(20-07) Predicting nickel mobility in sludge using PRZM 3.21, MINTEQA2 and FOCUS standard scenarios. Cheplick, J. Mark*,1, Ortego, Lisa2, 1 897-B Harrison St, Leesburg, VA2 2605 Meridian Parkway Suite 200, Durham, NC ABSTRACT- The fate of nickel in the environment, originating from the use of biodegradable waste as a soil enrichment, is governed by the complex interaction of numerous factors, including the physicochemical properties of nickel and nickel compounds, the chemical composition of the sludge and surrounding soil, the hydrogeological conditions of the application areas, and climatological conditions during and after application. Model scenarios were designed to reflect relatively worst-case conditions based on the variability in sludge composition, nickel concentration, application frequency, soil properties, and geographical location. Simulations were conducted for 26 years of historical weather records in order to evaluate nickel build-up and transport under varying climatological conditions. Several advantages in linking MINTAQA2 technology to FOCUS PRZM-3 include the following; (1) PRZM-3 has the ability to predict residence time, leaching, runoff, erosion, and uptake by plants. (2) PRZM-3 has been accepted as a risk assessment tool in the European Union. Standard scenarios exist for pesticide leaching and surface water risk assessments. The scenarios were developed by FOCUS, the Forum for the Coordination of Pesticide Fate Models and their Use (3) MINTEQA2 was used by the U.S.EPA to calculate Kd's for subsequent use in PRZM to address metal leaching from sludge-amended soil. This study involved a literature review to characterize the properties of municipal sludge, code development to automate calculations of sludge application to meet plant nutrient requirements, and the calculation of soil-water adsorption coefficients (Kd) for four different soil types (clay, loam, sandy loam, and silt loam). Kd's calculated for each soil type were determined for nine sorbent concentration/pH relationships, and six Ni-(Cd, Cu, Pb, Zn) divalent metals combinations. Results of the modeling are intended to better define the environmental fate of nickel from agricultural sludge applications. These results should aid in the calculation of more appropriate sludge limit values for agricultural use. Additionally, these data will provide fate information for risk assessments in the European Union and the Organization for Economic Cooperation and Development (OECD) for nickel and several compounds. Key words: nickel, przm focus, minteqa2 |
