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PH08 Metals in the Environment: Aquatic Biological Perspectives
(PH100) Development of a Chronic Biotic Ligand Model for Lead.
Brix, K1, Gerdes, R2, Grosell, M2, 1 EcoTox, Key Biscayne, Florida, United States2 RSMAS - University of Miami, Miami, Florida, United States
ABSTRACT- Acute and chronic biotic ligand models (BLMs) have been developed for Ag, Cu, and Zn, with BLMs for several other metals (Cd, Co, Ni) in various phases of development. Lead (Pb) represents another metal for which some development of an acute BLM has been undertaken. Our study represents initial efforts to develop a chrnic Pb BLM for the cladoceran Ceriodaphnia dubia (7 d survival and reproduction) and fathead minnow Pimephales promelas (30 d survival and growth). For each species, an initial series of Pb toxicity tests were conducted with varying Ca2+, dissolved organic carbon (DOC), and pH. C. dubia neonates used in testing were obtained from cultures acclimated to each of the test waters for several weeks. Similarly, larval P. promelas were acclimated to test waters for 7 d prior to testing. Additional testing with C. dubia also considered the effects of Na+, K+, Cl-, SO42- and HCO3- on chronic Pb toxicity. Initial testing with P. promelas showed all three parameters tested (Ca2+, DOC and pH) to have significant effects on chronic Pb toxicity. The ameliorating effect of Ca2+ on Pb toxicity appeared to plateau above 0.5 mM. For C. dubia, sufficient data were gnerated for us to develop an initial chronic BLM. Dissolved organic carbon, ph and HCO3- significantly influenced Pb toxicity. However, unlike findings with P. promelas, Ca2+ had no effect suggesting species-specific differences in Pb bioavailability and toxicity. Similar to observations on Ca2+ for P. promelas, the ameliorating effect of increasing HCO3- on chronic Pb toxicity for C. dubia appeared to plateau above 1 mM.
Key words: Biotic Ligand Model, Lead, Ceriodaphnia dubia, Pimephales promelas
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