Lead contamination and bioaccumulation in a lotic ecosystem around an abandoned mining area of Khliti Creek, Kanchanaburi province, Thailand

Abstract

This research investigated the lead contents of the water, sediment and freshwater organisms around an abandoned mining area in Kanchanaburi province, western Thailand. Samples were collected in 2017 during the monsoon season from three zones (upstream or control, middle-stream or inferred source and downstream or impacted zone) of Khli Ti creek. We found that the lead concentration of the water was the highest (0.0549 mg/l) on average in the downstream zone, and slightly exceeded the national standard level. In the sediment, the lead content was the highest (31,937.30 mg/kg) in the middle-stream zone and was approximately 25 times higher than the national standard level. The means of other selected heavy metal concentrations in the sediment were the following in descending order: Fe>Zn>As>Cd>Hg. The results also revealed lead accumulation in freshwater flora and fauna (plankton, macroinvertebrates, fish and macrophytes). Macroinvertebrates, in the middle-stream zone in particular, had the highest lead contents. Our study also showed the potential biomagnification of lead through the food chain. High contents of lead in organisms may cause both acute and chronic effects on stream dwellers on which further detailed research is needed. Lastly, the consumption of freshwater organisms by the local community should be avoided to reduce any health risks.