Distributions, sources, and ecological risks of hexachlorocyclohexanes in the sediments from Haihe Plain, Northern China

The levels of hexachlorocyclohexanes (HCHs) in the sediments from Haihe Plain, China, were measured by a gas chromatograph with a ⁶³Ni microelectron capture detector. The spatial distributions, possible sources, and potential ecological risks of these compounds were analyzed. The residual level of total HCHs was 33.84?±?173.37 ng?g^?1 dry weight (d.w.) with ranges of 0.13?～?1,107.41 ng?g^?1 d.w. Much higher ΣHCH contents were found in the lower reaches of some rivers and in the mouth of the main stream receiving tributaries. The predominance of β-HCH (36 %) in the sediments was similar to that in the soils from Haihe Plain. The high percentages of γ-HCH (23–41 %) could be detected at 25 % of the sampling sites in the seven river systems. There were statistically significant positive relationships between the contents of HCHs and total organic carbon. Lindane was identified as the primary source of HCHs in the sediments, and it seemed that recent illegal lindane inputs still existed in some areas in Haihe Plain, as indicated by the α-/γ-HCH and β-/(α?+?γ)-HCH ratios. Severe potential ecological risks of γ-HCH to benthic organisms at some sampling sites were found based on the consensus-based sediment quality guidelines.