Heavy Metals and Metalloids in Water and Bottom Sediments in the Rivers in the Can Gio Biospheric Reserve, Vietnam.

Chemoecological studies were carried out in the water areas of the Kagau and Longtau rivers in the Can Gio Biosphere Reserve (Vietnam). Mass-spectrometry analysis was used to determine the concentrations of 15 microelements (heavy metals and metalloids) in water and bottom sediments. The overall pollution level in the Can Gio rivers was found to be moderate. However, the concentrations of some heavy metals in several cases exceeded the maximum permissible concentration at short-time exposure; also, the limits of safe concentrations at chronic exposure were exceeded for some elements. The concentrations of some heavy elements amount to 30 to 80% of the MPC for water bodies used for fishery. Primarily, these are copper, zinc, arsenic, vanadium, iron, and molybdenum. It was found that, according to the Regulations of Vietnam, the waters of the examined water areas showed concentrations of suspended matter in excess of the standards for category A1 sources, and the concentration of dissolved oxygen in water was below the standard. The obtained results suggest the need to monitor the chemical–ecological conditions of rivers in Can Gio as protected natural objects, which are also used to some extent for social and economic purposes. [ABSTRACT FROM AUTHOR]