Model of the Fate of Chemicals in Sludge-Amended Soils with Uptake in Vegetation and Soil-Dwelling Organisms

Abstract

The BASL4 (Biosolids Amended Soil Level 4) soil biota models are described, applied, and discussed. The models simulate the fate of organic chemicals present in biosolids that are applied to a two-layer soil and address the processes of chemical degradation, volatilization, leaching, and sorption to decaying organic matter. Uptake in invertebrates (worms), small mammals (shrews), and vegetation is simulated involving three levels of complexity, namely simple equilibrium partitioning, steady state bioaccumulation and dynamic bioaccumulation models. A simulation of the fate of pyrene is presented to illustrate the model's capabilities. The model is successfully applied to the fate of triclosan in biosolids giving results in accord with monitoring data. The model results suggest that triclosan may biomagnify in a terrestrial food web. It is believed that the model is useful for assessing the bio-uptake of chemicals associated with biosolids, thus providing guidance on expected levels of contamination and the associated risks to wildlife.

Keywords:

• Soil-dwelling organisms
• bioaccumulation
• sludge-amended soil
• vegetation
• model
• biosolids
• fugacity