Environmental analytical research in Northern Vietnam - a Swiss-Vietnamese cooperation focusing on arsenic and organic contaminants in aquatic environments and drinking water

A long-term education and research partnership has been established between the Swiss Federal Institute for Environmental Science and Technology (EAWAG) and two university institutes in Hanoi. Here we give a summary report on environmental analytical investigations conducted in cooperation with the Hanoi University of Science focusing on (i) arsenic contamination in ground and drinking water, (ii) volatile organic compounds (VOCs) including disinfection by-products and chlorination practice in drinking water, (iii) analysis and occurrence of organophosphorus pesticides in rice growing areas, and (iv) chlorinated phenols and other chlorinated pollutants in wastewater of a pulp and paper mill. Arsenic concentrations ranged from 1 to 3050 μg/l (average 159 μg/l) in groundwater from the city of Hanoi and surrounding rural areas. The high arsenic levels indicate that several million people consuming untreated groundwater might be at a considerable risk of chronic arsenic poisoning. Water produced by the Hanoi waterworks is partly affected by arsenic, but VOCs and disinfection by-products were below international guideline limits. However, the current chlorination practice was found to be critical regarding water quality issues. Chlorinated pollutants were particularly abundant in wastewater effluents of pulp bleaching, suggesting that point-of-source treatment options should be implemented. The high pesticide concentrations measured in rice fields (>500 μg/l) were rapidly flushed into ambient surface waters, where beneficial organisms could be affected.