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

Abstract

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.