An integrative assessment to determine the sediment toxicity of Kaohsiung Harbor in Taiwan: combining chemical analysis and cytotoxicity assay

To evaluate the toxicity of sediments collected from the mouths of four rivers and entrances of Kaohsiung Harbor, Taiwan, a combination of in vitro cytotoxicity assays (Clone 9 cells) and chemical analysis that quantified 16 polycyclic aromatic hydrocarbons (PAHs), 10 phthalate esters (PAEs), and 2 alkylphenols (APs) was employed. Results showed that the total concentrations of PAHs, PAEs, and APs ranged between 77.9 and 24,363 ng/g dw, between 268 and 118,010 ng/g dw, and between 32.6 and 84,438 ng/g dw in sediments, respectively. The highest concentrations of PAHs, PAEs, and APs were found in the mouths of the Salt River (SR), Love River (LR), and Jen-Gen River (JR), respectively. Mean reference sediment quotient (m-RSQ) values were calculated using the chemical concentrations measured in the sediment of entrance I (EI) as the benchmark, and the order was SR > LR > JR > CR (Canon River mouth) > EII (entrance II) > EI. Results of the cytotoxicity assay showed that the 50% inhibitory concentration (IC50) of Clone 9 cells was in the order of LR < SR < JR < CR < EII < EI. Results on DNA content, apoptotic and autophagy protein biomarkers, and acridine orange staining indicated that the cause of death of Clone 9 cells after treatment with sediment extracts of the LR site was mainly through apoptosis. There was a significant correlation between m-RSQ values and IC50 of Clone 9 cells. The correlation analysis between cytotoxicity and chemical analytical data indicated that certain unknown chemicals may exist in LR sediment. Overall, this study demonstrated that the combination of chemical and biological analyses can provide a more comprehensive and realistic assessment of sediment toxicity to aquatic organisms compared to traditional chemistry-based-only analytical approaches.