Toxic Effects of Heavy Metals and Organic Polycyclic Aromatic Hydrocarbons in Sediment Porewater on the Amphipod Hyalella azteca and Zebrafish Brachydanio rerio Embryos from Different Rivers in Taiwan

The amphipod (Hyalella azteca) and zebrafish (Brachydanio rerio) embryos were used for toxicological sediment porewater testing. Porewaters from 35 sampling stations of eight streams in southern Taiwan were screened for toxic effects and their relationship with 6 metal and 16 polycyclic aromatic hydrocarbons (PAHs). Concentration analysis results showed that the following PAHs, naphththalene, benzo(b)fluoranthene, dibenz(a,h)anthracene, acenaphthalene, and the heavy metal cadmium were not detected in 35 sampling stations. The highest detection rate of 94.1% was caused by the PAHs fluoranthene and pyrene. The highest detection rate of the metal zinc was 88.6% of 35 analyzed samples. The majority of samples (88%) were classified as level tier 1 according to USEPA national sediment inventory. This indicates the probability of adverse effects on aquatic life or human health. The results of a zebrafish embryo test showed that heart rate and survival were significantly reduced with all porewater samples. Therefore, fish exposed to contaminated river conditions may be affected in their cardiovascular functions. Looking at correlations between toxic effects of metals and PAHs, we found that phenanthrene, anthracene, pyrene, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, and benzo(a)pyrene were low, while fluorene was highly correlated with toxic effects of metals.

Automated summary

The porewater from 35 sampling stations of eight streams in southern Taiwan were tested for toxic effects using amphipod and zebrafish embryos. While some PAHs and heavy metals were not detected, there were still concerns about potential adverse impacts on aquatic life and human health. The zebrafish embryo test indicated that heart rate and survival were significantly reduced with all porewater samples, suggesting potential cardiovascular effects for fish exposed to contaminated river conditions. Further analysis revealed correlations between certain PAHs and toxic effects of metals, with fluorene showing a high correlation.