A survey of surface and groundwater quality contamination in south-central coastal Vietnam

Contamination of groundwater is posing a threat as a result of intensification of agriculture in south-central coastal (SCC) Vietnam. Increased use of chemical fertilisers on rice and vegetable crops and increased density of cattle around settlements are the main reasons for groundwater contamination. Villagers are dependent on groundwater and stream water as a supply for daily use and for crop irrigation. The risk of surface and groundwater contamination from nutrient run-off and leaching is likely to be high in coastal areas as the majority of the soils represent sands. However, few data exist to confirm this. The objective of this study was to collect and test water samples from various sources (bore wells, open wells, streams and irrigation canals) at different times of the year—mainly from An Chan commune, Tuy An district, Phu Yen province, where intensification of crops and livestock has taken place in recent years. Sampling was carried out from April 2011 to April 2012. The results indicated that dissolved phosphate (PO43–) and nitrate (NO3–) levels mainly met the criteria that are regulated for drinking water, at least to the minimum standard. However, in some samples of surface water for phosphate and surface and groundwater for nitrate, the levels were too high—up to 10.9 mg NO3–/L was found in stream/canal water, and up to 14 mg PO43–/L and 50 mg NO3–/L in groundwater. These results confirm that contamination of surface and groundwater is a problem affecting An Chan commune and highlights the need to implement strategies to improve nutrient management on coastal sands in the SCC region. The outcomes from this study confirm that future detailed research is required to determine the sources of water contamination. Key sources are likely to include fertilisers applied to rice and vegetables, wastes from cattle and fisheries, and also human waste, due to lack of proper drainage systems in this regio