Metal Concentrations and Responses of Chironomid Larvae Exposed to Thailand Pulp and Paper Mill Effluent

Pulp and paper mills (PPM) may discharge insufficiently treated waste into rivers and give rise to serious effects with aquatic life. This study investigated the biological response of the chironomid (Chironomus javanus, Kieffer) when exposed to PPM effluent. Effluent concentrations of BOD, COD, TKN, TS, Cr, Cu, Pb and Zn were high. Cd and Cr concentrations in chironomid were the most accumulated. Whole effluent toxicity on the chironomid test organism was significant as expressed by the percent survival and decreased with increasing concentration. Highest dry weight, head capsule and length of the chironomid test organism corresponded to 100% effluent at a specific time. Effect of dilution was assessed by using glutathione S-transferase activity on chironomid and corresponded to 6.25% effluent during 48-96 h which was significantly increased in the chironomid. The results showed that the chironomid was sensitive to PPM effluent and toxicity tests can be used for assessing the effect of effluent on aquatic species.