Leachate toxicity assessment by responses of algae Nitellopsis obtusa membrane ATPase and cell resting potential, and with Daphtoxkit F™ magna test

A microscale bioassay based on 50% inhibition of K ,M g 2 -ATPase activity in a microso- mal fraction isolated from Nitellopsis obtusa cells was developed. Compared to that for a plasma membrane fraction purified in a sucrose gradient, the preparation procedure for a microsomal fraction is less time consuming and the yield is substantially higher. Characteristics of the microsomal preparation proved to be similar to those of the highly purified plasma membrane preparation (Manusadzianas et al., 2002), at least for heavy metals. Sensitivity to CuSO4 of the frozen (8°C) microsomal fraction (49 17 (SD) M; n 8) did not significantly differ from that of the freshly isolated one (52 30, n 8), at least for 40 days. Toxicity of leachate water from Kairiai (northern Lithuania) solid waste landfill was assessed by taking samples from various points including temporary reservoirs and analyzing them immediately after spillage (summer 2002) and after storage for almost 2 years at 4°C- 6°C. Two tests with the macrophytic alga Nitellopsis obtusa (Charatox, 45-min EC50 of resting potential depolarization, and ATPase assay, IC50 of membrane ATPase activity) and one test with the crustacean Daphnia magna (Daphtoxkit F™, 48-h 50% immobilization) tests were used. In general, all three tests showed successively decreasing values of landfill leachate toxicity with an increasing degree of dilution with surface waters. The possibility of employing preserved algal preparations on demand in test batteries seems to be promising, especially in emergencies. © 2004 Wiley Periodicals, Inc. Environ Toxicol 19: 403- 408, 2004.