Effect of historical residual hexachlorocyclohexanes and dichlorodiphenyltrichloroethane on bacterial communities in sediment core collected from an estuary in northeastern China by next-generation sequencing.

In this study, we evaluate the influence of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethane (DDT) on bacterial communities of sediment core from an estuary formed during the period of 1960-2011. Canonical correspondence analysis showed that o,p'-DDT, o,p'-DDD (mitotane), and depth had important influences on bacterial community distributions (p<0.05). Furthermore, our results found variance explained by all variables was 82.9%, while that by o,p'-DDD was 24.4%, and that of o,p'-DDT was 9.8%, indicating that o,p'-DDD had a greater influence on sediment-dwelling bacteria than o,p'-DDT. Also, bacterial diversity was affected and the Shannon index was significantly negatively correlated with total HCHs (r=-0.579, p<0.05) and total DDTs (r=-0.607, p<0.01), respectively. Furthermore, our results showed that Flavobacteria and Clostridia content can be considered an indicator of pollution of HCHs and DDTs in sediment core samples.