Occurrence of organochlorine residues in surface water and mussel Corbicula sumatrana from Lake Singkarak, West Sumatera

Organochlorine is a synthetic pesticide that has been banned in many countries because of its high persistence in the environment and can accumulate in animals. The goal of our study was to determine the level of organochlorine residues in surface water and in the mussel Corbicula sumatrana of Lake Singkarak. Water and mussel samples were collected from 10 sampling sites of Lake Singkarak, Batu Taba, Sumpur, Guguk Malalo, Ombilin, Tikalak, Sumani, Saniang Baka, Muaro Pingai, Paninggahan, and Tanjung Mutuih, respectively in June 2021. Water and mussel samples were extracted and analyzed with gas chromatography. The result of our study revealed the occurrence of Lindan (7 μg/L) in the surface water of Tikalak, and also Aldrin (3 μg/L) in the surface water of Tikalak, Sumani, and Ombilin. Organochlorine residue compounds were also detected in mussels of five sampling sites (Tikalak, Sumani, Muaro Pingai, Paninggahan, and Tanjung Mutuih). Mussels of Tikalak contain compounds namely Dieldrin, Dichlorodiphenyltrichloroethane (DDT), and Endosulfan with levels of 2 μg/kg, 6 μg/kg, and 3 μg/kg, respectively. Dieldrin was also detected at Sumani (2 μg/kg), Muaro Pingai (4 μg/kg), and Paninggahan (10 μg/kg). DDT was also detected at Tanjung Mutuih at a level of 3 μg/kg. Other compounds such as Heptachlor and Endrin were not detected both in surface water and in mussel from all sampling sites studied. The results indicate that organochlorine residue can still be found in the environment, with its level in mussels being higher than in surface water.