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(+), Mg(2+)-ATPase activity in a microsomal 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 CuSO(4) of the frozen (-8 degrees C) microsomal fraction [49 +/- 17 (SD) microM; 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 degrees C-6 degrees C. Two tests with the macrophytic alga Nitellopsis obtusa (Charatox, 45-min EC(50) of resting potential depolarization, and ATPase assay, IC(50) 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.

Ecotoxicological study of Lithuanian and Estonian wastewaters: selection of the biotests, and correspondence between toxicity and chemical-based indices.

The toxicity of industrial and urban wastewater (WW) samples collected in Lithuania and Estonia was evaluated by using a suite of biological tests comprising the Algaltoxkit F with Selenastrum capricornutum, the Charatox with Nitellopsis obtusa, Daphtoxkit F with Daphnia magna, Thamnotoxkit F with Thamnocephalus platyurus, Protoxkit F with Tetrahymena thermophila and the Microtox with Vibrio fischeri. The Charatox and Thamnotoxkit F tests showed highest relative sensitivity, responding to 80-90% of samples, respectively, and both expressed good discrimination capacity between samples. Principal Component and pairwise correlation analysis allowed to select test-battery consisting of Charatox, Thamnotoxkit and Microtox. The WW toxicity was evaluated by means of cumulative indices such as average toxicity (AvTx) and two indices derived from the PEEP-index (Environ. Toxicol. Water Qual. 8 (1993) 115). In addition to these integrated evaluations of test-battery response, WW toxicity was evaluated according to the most sensitive test (MST) in the battery. The linear regression analysis between cumulative toxicity indices and chemical-based indices (derived from comparison of WW chemical concentrations and their respective maximum allowable concentration) revealed positive linear relationships (r(2)=0.7-0.8), while toxicity evaluation based on the MST was less positively related with chemical analysis data (r(2)=0.5-0.6). Although better coincidence between the toxicity and chemical-based assessments was achieved when information from all tests in the battery was assembled, the prediction of toxicity from chemical data was still limited. In search of suitable test-battery for the screening of certain type of WWs, a preliminary study comprising excessive suite of tests might be useful.

Phytotoxicities of Selected Chemicals and Industrial Effluents to Nitellopsis obtuse Cells, Assessed by Using a Rapid Electrophysiological Charophyte Test.

The acute phytotoxicities of seven heavy metals (Cd2+, Cu2+, Hg2+, Ni2+, Zn2+, Cr6+ and Co2+), three phenolic compounds (phenol, 3,5-dichlorophenol and pentachlorophenol) and nine industrial effluents were appraised by using a rapid electrophysiological test with cells of the charophyte, Nitellopsis obtusa. The EC50 values (concentrations causing a 50% decrease in resting potential) obtained for reference chemicals were compared with those of five microbiotests (Polytox®, Microtox®, Selenastrum capricornutum growth inhibition, Daphnia magna immobilisation and Rotoxkit F™) taken from the scientific literature. The 45-minute charophyte test, the freshwater Algaltoxkit F™, Daphtoxkit F™ and Rotoxkit F™ were conducted simultaneously to assess the toxicities of effluents. The Toxkit microbiotests were typically two orders of magnitude more sensitive than the electrophysiological charophyte test to pure chemicals. The electrophysiological charophyte test was generally more sensitive than the Toxkit microbiotests to complex effluents. The rapid electrophysiological test, employing the 45-minute membrane depolarisation of N. obtusa cells as an endpoint, demonstrated similar sensitivity to heavy metals and phenolic compounds as the 20-minute bacterial Polytox® test, but less sensitivity than the 15-minute Microtox® test. Therefore, this rapid macroalgal test appears to be valuable as a sublethal toxicity screening tool for effluents.