Antibiotics and pesticides in water and sediments from intensive shrimp farms in Southern Vietnam: Preliminary results

Vietnam is one of the largest shrimps exporters in the world. Intensive shrimp farming uses a lot of insecticides to sanitize the shrimp ponds and antibiotics for the prevention of diseases. The aims of this study are to develop a passive sampling method for evaluation of six antibiotics and twelve pesticides in the surface water and determine the contamination of surface waters and sediments by these compounds in Can Gio district – Ho Chi Minh City and Long An province, two major intensive shrimp farming sites in Southern Vietnam. Passive samplers (Polar Organic chemical Integrative Samplers - POCIS) enable to calculate time-weighted average concentrations of the free dissolved fraction of pollutants and thus provide precious data about pollutant bioavailability. The results shown that, passive sampling with POCIS is quite effective for evaluation of antibiotics and pesticides in surface water. The antibiotics and pesticides were found in both surface waters and sediments from the shrimp ponds and the canals. The maximum aqueous concentrations of antibiotics and pesticides were found in the shrimp ponds, 2'800 ng/l and 250 ng/l respectively. In the sediments concentrations of antibiotics and pesticides were close to 1'000 ng/kg. A new project is in preparation to confirm these findings and to extend the investigation to others shrimp farms. Possible antibiotic resistance by natural bacterias will also be investigated.