Ecotoxicity of sediments in Ho Chi Minh city's canals

Abstract

For an ecotoxicological screening of recently deposited sediments, samples were collected from Ho Chi Minh City's canals in August 2015. The sediments were characterized by physico-chemical analysis of metals, PAHs, PCBs, and other organic micropollutants, and standard sediment toxicity testing. The results showed that the sediments from the canals from both the urban and suburban areas contained a mixture of contaminants with concentrations of several metals, PAHs, PCBs and OCs being above thresholds for effects to benthic organisms. The results of the chemical analyses were corroborated by toxicity detected in standard laboratory tests with crustaceans (ostracods) and insect (midge) larvae. Conspicuous concentrations at the μg/g level were found for the fragrances galaxolide and OTNE, and nonylphenol, triclosan and the UV filters octocrylene, 2-EHDP and EHMC were measured at all sampling sites at concentrations of several tens and even hundreds ng/g. Highest concentrations were measured for the pyrethroid insecticide permethrin in sediments from the urban area and for the pyrethroid insecticide bifenthrin in sediments from suburban areas (3692.9 ng/g dw and 477.6 ng/g dw, respectively). Insecticides were identified as the most probable contributors to the observed toxicity.