Modeling historical budget for β-Hexachlorocyclohexane (HCH) in the Arctic Ocean: A contrast to α-HCH

The historical annual loading to, removal from, and cumulative burden in the Arctic Ocean for β-hexachlorocyclohexane (β-HCH), an isomer comprising 5–12% of technical HCH, is investigated using a mass balance box model from 1945 to 2020. Over the 76 years, loading occurred predominantly through ocea...

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Bibliographic Details
Published in:Environmental Science and Ecotechnology
Main Authors: Pu-Fei Yang, Robie W. Macdonald, Hayley Hung, Derek C.G. Muir, Roland Kallenborn, Anatoly N. Nikolaev, Wan-Li Ma, Li-Yan Liu, Yi-Fan Li
Format: Article in Journal/Newspaper
Language:English
Published: Elsevier 2023
Subjects:
β-Hexachlorocyclohexane
Arctic Ocean
Mass balance model
Budget
Air-water exchange
envir
geo
Arctic
Climate change
Online Access:https://doi.org/10.1016/j.ese.2022.100229
https://doaj.org/article/8f1afc428c644e64a39766550d1d9a5b
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Summary:The historical annual loading to, removal from, and cumulative burden in the Arctic Ocean for β-hexachlorocyclohexane (β-HCH), an isomer comprising 5–12% of technical HCH, is investigated using a mass balance box model from 1945 to 2020. Over the 76 years, loading occurred predominantly through ocean currents and river inflow (83%) and only a small portion via atmospheric transport (16%). β-HCH started to accumulate in the Arctic Ocean in the late 1940s, reached a peak of 810 t in 1986, and decreased to 87 t in 2020, when its concentrations in the Arctic water and air were ∼30 ng m−3 and ∼0.02 pg m−3, respectively. Even though β-HCH and α-HCH (60–70% of technical HCH) are both the isomers of HCHs with almost identical temporal and spatial emission patterns, these two chemicals have shown different major pathways entering the Arctic. Different from α-HCH with the long-range atmospheric transport (LRAT) as its major transport pathway, β-HCH reached the Arctic mainly through long-range oceanic transport (LROT). The much higher tendency of β-HCH to partition into the water, mainly due to its much lower Henry's Law Constant than α-HCH, produced an exceptionally strong pathway divergence with β-HCH favoring slow transport in water and α-HCH favoring rapid transport in air. The concentration and burden of β-HCH in the Arctic Ocean are also predicted for the year 2050 when only 4.4–5.3 t will remain in the Arctic Ocean under the influence of climate change.

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