M7 AM Metals in the Environment: Chemistry and Fate Issues
Monday, 14 November 2005: 8:00 AM - 11:40 AM in 327-329

(FAR-1117-856769) Evaluation of critical metal loads using the Unit World Model for lakes.

Farley, K^{1, 2}, Carbonaro, R¹, Di Toro, D^{2, 3}, ¹ Manhattan College, Riverdale, NY, USA² HydroQual, Inc., Mahwah, NJ, USA³ University of Delaware, Newark, DE, USA

ABSTRACT- The overall goal of this work is to develop a quantitative method or model for assessing the risks posed by metal inputs to lakes. For initial lake applications, we have considered a vertically well-mixed water column overlying a sediment layer. Processes specifically considered in the model include dissolved and particulate phase transport, a simplified description of the biogeochemical cycling of organic carbon and sulfur, metal complexation to organic carbon and inorganic ligands (as described by WHAM), and competitive interactions of metals and major cations to the biological site of action for water column and sediment-dwelling organisms (as described by the Biotic Ligand Model). The model calculations are used to evaluate the relative ranking for the critical loading of metals (Cd, Cu, Ni, Pb, Zn) in an idealized lake. In addition, the cycling of metals is examined and is shown to be a function of metal binding affinity to organic carbon, pH, hardness, organic carbon production rates, and organic carbon diagenesis and net sulfide production in sediments.

Key words: metals, fate, effects, model