Hexachlorocyclohexane - Long term variability and spatial distribution in the Baltic Sea. (February 2017) - Abraham, Marion
Abstract: In response to the HELCOM commitment the Leibniz Institute for Baltic Sea Research Warnemuende conducts a monitoring program on listed substances of concern for the Baltic Sea environment which comprises the isomers of technical hexachlorocyclohexane (HCH). After World War II the HCH compounds were applied globally in huge amounts as insecticidal formulation in which only γ-HCH is the effective agent. Monitoring was conducted in water samples from a large Baltic Sea area. Mostly, the HCH compounds were evenly distributed in the Baltic Sea. Data from 1975 to 2015 from the Arkona Basin depict a substantial reduction of the HCH pressure (12, 500 to < 400 pg/L). Longest residence is shown for β-HCH, which is currently the predominant HCH isomer in the Baltic Sea (α/β/γ:1/2/1). Half lives were determined to be 4–8 years for α- and γ-HCH and 5–20 years for β-HCH. Graphical abstract: Highlights: Substantial reduction of the HCH pressure for the Baltic Sea during the past 40 years. The β-isomer is currently the predominant HCH isomer (α/β/γ: 1/2/1) and will remain longest in the Baltic Sea. Inflow events from the North Sea temporarily influenced HCH concentrations of surface and deep water body of the Baltic Sea.