PARENT SESSION
70 - Metal Pollution: From Exposure to Ecological Effects
8:00 AM to 6:30 PM, Wednesday, 15 May 2002
Exhibition Area

(70-54) Determining Bioavailable Copper in Estuarine Systems: Toxicity to Americamysis bahia.

Dietrich, Andrea^*,1, Gallagher, Daniel¹, Postlethwait, Niel^1,2, Snyder, Jeffery^1,3, ¹ Department of Civil and Environmental Engineering, Blacksburg, VA² CH2MHill, Tampa, FL³ Earth Tech, Greenville, SC

ABSTRACT- In coastal areas, copper is used as an agricultural pesticide to control plant fungal and bacterial diseases. A cation exchange resin that distinguished weakly and strongly bound copper was use to measure bioavailable copper in estuarine waters and to predict copper toxicity to mysid shrimp (Americamysis bahia) in presence of natural organic matter (NOM). Resin-bound dissolved copper was operationally defined as bioavailable. Percent bioavailable copper was not affected by varying initial copper concentration or by varying total Cu concentration in presence of NOM. The percent bioavailability decreased as pH increased and as NOM increased. MINEQL+ modeling indicated that the resin accurately retained bioavailable copper for pH values from 5.5 to 8.5 and in the presence of NOM. Acute toxicity bioassays performed with mysids evaluated copper toxicity in the presence of Suwannee River Fulvic Acid. Static or static renewal tests- EPA method OPPTS 850.1035 with at least 10 mysids per condition- were used to determine LC50 and EC50 values for copper and NOM. Test solutions consisted of artificial seawater at 20 ppth; 0, 100, 200, 400, or 800 ug/L copper; 0, 12, or 24 mg/L NOM. Forty-eight hour acute toxicity tests were performed on larval (2 to 3 day) mysid shrimp that were fed Artemia (brine shrimp); mortality and immobilization were the endpoints. The 48-hour LC50 values were 200, 340, and 495 ug/L dissolved copper for 0, 12 and 24 mg/L NOM. Based on resin measurements, 48-hour LC50 values were 94, 98, and 105 ug/L bioavailable copper for 0, 12 and 24 mg/L NOM. The consistency of the LC50 measurement using bioavailable Cu suggested that the resin is a useful technique for toxicity analysis in saline water.

Key words: copper, bioavailability, toxicity, mysids