Toxicity of sediments from the Ho Chi Minh City canals and Saigon River, Viet Nam

Toxicity of sediment from waterways of Ho Chi Minh City (HCMC), Viet Nam, w as assessed in aqueous and organic extracts using the organisms Daphnia mag na and Vibrio fischeri. Sediment samples were taken along the main canals o f HCMC and in the Saigon river. The results indicate a relatively high pote ntial toxicity of the extracts, especially concerning the aqueous extracts. V. fischeri shows a higher sensitivity than D. magna for both types of ext racts. Sediments from the canals in the urban areas, where the industrial a nd domestic activities are concentrated, indicate a higher potential toxici ty than sediments from the river. Organic extracts of deep sediments (about 1.3 m) are less toxic than surface sediment. The toxicity of the organic s ediment extracts was higher in 1999 than in 1996, except for one site, wher e dredging operations have been carried out since 1997. The dredging operat ions thus have a positive local effect on the sediment quality, but further consequences on water and sediment quality of HCMC canals and rivers still have to be evaluated. (C) 2000 by John Wiley & Sons, Inc.