Influence of Water Hardness on Ecotoxicology of Copper on Aquatic Biota: Implication for the Revision of Water Quality Standardization in Lao PDR.
2016 年 7 巻 2 号 p. 12-17
詳細
2016 年 7 巻 2 号 p. 12-17
The ecotoxicology of copper on freshwater organisms were studied using field-collected water from two local sites along Lower Mekong Basin in Lao PDR, which focused on different water hardness 20±2.83 and 108±0.00 mg L-1 as CaCO3 (water in rainy season), 105±3.35 and 140±4.00 mg L-1 as CaCO3 (water in dry season) and distilled water was reconstituted by adding reagent-grade chemicals which reconstituted water hardness 18±3.58 and 86±4.56 mg L-1 as CaCO3. In this study, the US EPA method was used for the acute toxicity test to juvenile Cyprinidae (Labeo rohita) and Moina macrocopa at different water hardness. Mortalities were at 24, 48, 72 and 96 hr for L. rohita and 48 hr for M. macrocopa. At water hardness of 20±2.83 mg L-1 as CaCO3, the percentage mortality of L. rohita was 100% at 96 hr by Cu 0.13 mg L-1. The mortality was 100% at 96 hr of water hardness 108±0.00 mg/L as CaCO3 at Cu 0.37 mg L-1. There was a 3-fold increase in water hardness (from 20±2.83 and 108±0.00 mg L-1 as CaCO3) and Cu was highly significantly toxic to L. rohita. The percentage mortality of L. rohita was 100% at 96 hr by Cu 0.37 mg L-1, on 105±3.35 and 140±4.00 mg L-1 as CaCO3, and both were highly significant difference (P < 0.001). A 8-fold increase in water hardness (from 105±3.35 and 140±4.00 mg/L as CaCO3) and Cu was significantlytoxic to L. rohita. At 20±2.83 mg L-1 as CaCO3 hardness, the percentage mortality of M. macrocopa of 100% was very highly significant at 48 hr by Cu 0.07 mg L-1, while percentage mortality was 100% at 48 hr of water hardness 108±0.00 mg L-1 as CaCO3 at Cu 0.13 mg L-1, the difference was highly significant as well. A 3-fold increase in water hardness (from 20±2.83 to 108±0.00 mg L-1 as CaCO3) had significant toxic effect of Cu to M. macrocopa with overlapping 95% confidence intervals of LC50 values. The percentage mortality of M. macrocopa of 100% at 48 hr by Cu 0.13 mg L-1, on water hardness of 105±3.35 and 140±4.00 m L-1 as CaCO3, were both highly significant. A 2-fold increase in water hardness (from 105±3.35 and 140±4.00 mg L-1 as CaCO3) did not significantly (P > 0.05) have toxic effect of Cu to M. macrocopa. The effects of Cu on organisms depend on water hardness, i.e., increasing water hardness reduce the toxic effect of Cu on aquatic organism.
