3.3. Toxicity of wastewater
Both test species are similarly sensitive to the wastewater as assessed in acute toxicity tests (Fig. 3, Table 5 and Table 6). Toxicity increased with increasing duration of exposure to the wastewater, with significant mortality of the microgastropod occurring at concentrations as low as 3.125% after prolonged exposure over 14 to 21 days (Table 6, Fig. 3). Significant mortality was observed following 4 days of exposure to 25% wastewater in both species; at 50% wastewater, significant mortality of the microgastropod and amphipod was observed after 1 and 2 days respectively (Table 5 and Table 6, Fig. 3). The minimum dilution of wastewater required to cause no impacts to either species in short term one day exposures was 25% wastewater (NOEC) (Table 5 and Table 6). Control survival in all tests was greater than 80% (Fig. 3) and within the acceptable limits for routine invertebrate toxicity testing. Amphipods and microgastropods were of similar sensitivity to wastewater, and responded over a similar period of time. Wastewater was toxic to biota at concentrations as low as 3.125% (LOEC, Microgastropod test 2) over a 21 day exposure period (Fig. 3). Acute effects in both amphipods and microgastropods were observed in wastewater discharged from the SMQ (test 1) after only a 24 h exposure, with 100% mortality at the highest wastewater concentrations tested (68%) for both species, and at 50% wastewater for the amphipod. In comparison, both species were initially slower to respond to exposure to the composite wastewater (test 2), with 100% mortality of amphipods occurring within 7 days at wastewater concentrations ≥ 25%, and within 4 days at concentrations ≥ 50% in the microgastropods (Fig. 3). While effects on biota were delayed, the composite wastewater was more toxic than the SMQ discharged wastewater over longer exposure periods with 100% mortality at 21 days in all concentrations except the lowest tested (3.125%).
3.3. ความเป็นพิษของน้ำเสียBoth test species are similarly sensitive to the wastewater as assessed in acute toxicity tests (Fig. 3, Table 5 and Table 6). Toxicity increased with increasing duration of exposure to the wastewater, with significant mortality of the microgastropod occurring at concentrations as low as 3.125% after prolonged exposure over 14 to 21 days (Table 6, Fig. 3). Significant mortality was observed following 4 days of exposure to 25% wastewater in both species; at 50% wastewater, significant mortality of the microgastropod and amphipod was observed after 1 and 2 days respectively (Table 5 and Table 6, Fig. 3). The minimum dilution of wastewater required to cause no impacts to either species in short term one day exposures was 25% wastewater (NOEC) (Table 5 and Table 6). Control survival in all tests was greater than 80% (Fig. 3) and within the acceptable limits for routine invertebrate toxicity testing. Amphipods and microgastropods were of similar sensitivity to wastewater, and responded over a similar period of time. Wastewater was toxic to biota at concentrations as low as 3.125% (LOEC, Microgastropod test 2) over a 21 day exposure period (Fig. 3). Acute effects in both amphipods and microgastropods were observed in wastewater discharged from the SMQ (test 1) after only a 24 h exposure, with 100% mortality at the highest wastewater concentrations tested (68%) for both species, and at 50% wastewater for the amphipod. In comparison, both species were initially slower to respond to exposure to the composite wastewater (test 2), with 100% mortality of amphipods occurring within 7 days at wastewater concentrations ≥ 25%, and within 4 days at concentrations ≥ 50% in the microgastropods (Fig. 3). While effects on biota were delayed, the composite wastewater was more toxic than the SMQ discharged wastewater over longer exposure periods with 100% mortality at 21 days in all concentrations except the lowest tested (3.125%).
การแปล กรุณารอสักครู่..