08. ASSESSMENT OF RESIDUAL OF OGANOCHLORINE INSECTICIDES IN THE COASTAL RIVER AREA AT KIM SON DISTRICT - NINH BINH PROVINCE

Tóm tắt

Sediment samples in coastal estuary of Kim Son district, Ninh Binh province were collected continuously at 3 sites for 3 years from 2016 to 2018 in June of each year. After taken, organochlorine insecticides content in sediment samples was determined by an electron trap detector using Agilent 7697A Headspace Sampler, model: 7890B/7697A/7000C. Analyzed result showed that total DDT content in the study area was in ranged from 0,0115 to 0,0415 ppm, HCH content was in range of 0,0326 to 0,0889 ppm, total aldrin and dieldrin in range of 0.012 to 0.046 ppm and endrin in range of 0 to 0,0015ppm. Organochlorine insecticides content tended to decrease over time, the slope of the linear equation for DDT varied from - 0.0002 to - 0.0011 smaller than the coefficient of HCH and total cyanosis showed that the rate of HCH and total cyanosis decreased more rapidly than DDT over time. No g-HCH was detected in all analyzes, ratios of DDT/DDE, DDT/DDD, DDT/total DDT and DDD in 2017 and 2018 were 0,0 indicating that the study area was no longer receiving pesticides from other places. It is realized that topographic factors play a decisive role in the accumulation of pesticides residues. This is evidenced by the higher pesticide content in sediment in mangroves than in sediments in aquaculture and mudflats due to less susceptibility to erosion and frequent embossed sedimentation.