Chironomus riparius sediment chronic toxicity testing was developed based on the European Union's relevant sediment toxicity test protocol in current project. Acute (survival) and chronic (survival and growth) toxicity test endpoints were monitored and results compared to the standard method for Hyalella azteca toxicity testing. A TRIAD risk assessment procedure was carried out for the Da-an (DA1~DA3) and Erren River (SYR, SY1及SY2) Basins, which included chemical analysis (copper, zinc, chromium, cadmium, lead, nickel, arsenic, mercury, iron, and manganese), biological toxicity (Chironomidae and Amphipoda), and ecological investigation (abundance index, diversity index, and Hilsonhoff family biological index). Under a thrice-weekly water renewal exposure condition, we observed that C. riparius survival was ≧ 70%, which met the acceptability criteria for survival testing. Sediment and biota samples were collected in March and July through August, 2019. Sediment trace metal analysis showed that only nickel exceeded the sediment quality guideline low value (SQG low) in the Da-an River watershed, whereas trace metals in the Erren River watershed reached an SQG high of 22.5%. H. azteca survival and growth in acute and chronic toxicity tests conducted on Erren River watershed sediments were significantly different from the control group. Chironomidae toxicity testing showed that the head capsule width and emergence rate of C. riparius was significantly inhibited compared with the control group (p < 0.05) in acute and chronic toxicity test endpoints at site SY1. In the ecological survey, four families and eight species of fish and 13 orders and 17 families of benthic organisms are recorded from the Da-an River. Five families and seven species of fish and 7 orders and 13 families of benthic organisms are recorded from the Erren River. Our results show that the pollution level of the Da-an River is relatively slight. In our survey, the three-tiers valuation results from the integrated weight data for sediment quality (chemical, toxic, and ecological) showed that stations DA1, DA2, DA3, and SYR are chemical-toxic stressed (although resistance may have developed at the community level), and there were significant adverse effects and high risk from sediment contamination at stations SY1 and SY2.

Amphipods, Chironomid, TRIAD, Sediment Quality Guidelines