Whole-sediment toxicity tests are increasingly being used in ecological risk assessments of sediment contaminants. Two sediment chronic toxicity tests were used to predict the sublethal effects of chemicals of potential concern (COPCs) on a sediment-dwelling amphipod (Hyalella azteca) and a fish (Paramisgurnus dabryanus). Sublethal endpoints measured and reported herein include the survival and growth of H. azteca and growth of Paramisgurnus dabryanus exposed to field sediments. Toxicity and chemical analyses (metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, and organochlorine pesticides) of sediments from four watersheds were conducted. The project has completed fifteen literature reviews. Station LK2 was severely polluted with heavy metals (Cd, Cr, Cu, Pb, Hg, Ni, and Zn, but not As), while other metals were above sediment quality guideline lower limits. Furthermore, the detected concentrations of Hg, Ni, and Zn were 1.3 - 3.8 times higher than their maximum acceptable limits. Nickel most frequently exceeded its lower limit, followed by zinc, indicating that these two metals may be prevalent in river sediments. In contrast, mercury had the lowest detection rate (60%). Polycyclic aromatic hydrocarbon analyses demonstrated that three PAHs, namely fluoranthene, pyrene, and benzo(a) anthracene, were detected in all samples but at concentrations below their lower limits. Additionally, station SY1 was contaminated with 15 PAHs. Dibenz(a,h)- perylene was the only non-detected compound tested for. Among 16 PAHs tested, acenaphthalene exceeded its upper limit at stations ER2, ER3, and ER6, possibly posing ecological risks. Two other classes organic contaminants (total polychlorinated biphenyls and organochlorine pesticides) tested for in sediments were not detected. The potential effects of contaminants in sediments were evaluated through 28-day Hyalella azteca survival/growth toxicity testing. The amphipod control group’s survival was higher than 80%, meeting acceptable minimum survivorship. Amphipod survival was reduced at stations SY1, SY3, and HJ1 to only 35, 8.8, and 0%, respectively, and average amphipod weights were 32 - 39% lower than controls. In addition, the evaluation of fish growth affected by 20 sediment samples was done for eight weeks by tracking body length, body weight, feed conversion rate, condition factor, survival, and specific growth rate of fish as indicators. No significant differences in survival, condition factor, and feed conversion rate were recorded between controls and treatments. Fish exposed to treatments with SY2, ER1, ER5, HJ2, HJ3, HJ4, and DG1 sediments had significantly shorter body lengths in comparison to controls. Significant decreases in body weight and specific growth rate were measured in fish reared under exposures to ER1, HJ2, HJ3, HJ4, and HJ5 sediments for eight weeks compared to controls. The relationships between toxicity and sediment chemical characteristics were further analyzed by a Spearman rank correlation analysis. This indicated significant correlations (P < 0.05) between H. azteca growth (body length) and nickel and the PEC-Q for organochlorine pesticides. The body weight of H. azteca was significantly correlated with Benzo(a) anthracene, although the calculated ∑ESBTU values of PAH were significantly correlated to the length of H. azteca. In addition, the survival, body length, body weight, condition factor, and specific growth rate of P. dabryanus were not significantly correlated to any of the sediment contaminants analyzed. Therefore, in addition to chemical analyses, toxicity tests can provide valuable, more realistic information toward understanding the impacts of sediment contaminants on aquatic biota.

Sediment toxicity, Sediment toxicity, metals, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, organochlorine pesticides, Sediment-dwelling organism