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

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

doi:10.1016/j.ese.2022.100229

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

Environ Sci Ecotechnol. 2022 Nov 30:14:100229. doi: 10.1016/j.ese.2022.100229. eCollection 2023 Apr.

Authors

Pu-Fei Yang^{1

2}, Robie W Macdonald^{3

4}, Hayley Hung⁵, Derek C G Muir⁶, Roland Kallenborn⁷, Anatoly N Nikolaev⁸, Wan-Li Ma^{1

2}, Li-Yan Liu^{1

2}, Yi-Fan Li^{1

2

9}

Affiliations

¹ International Joint Research Center for Persistent Toxic Substances (IJRC-PTS), State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin, 150090, China.
² International Joint Research Center for Arctic Environment and Ecosystem (IJRC-AEE), Polar Academy, Harbin Institute of Technology, Harbin, 150090, China.
³ Institute of Ocean Sciences, Department of Fisheries and Oceans, Sidney, BC, V8L 4B2, Canada.
⁴ Centre for Earth Observation Science, University of Manitoba, Winnipeg, R3T 2N2, Canada.
⁵ Air Quality Processes Research Section, Environment and Climate Change Canada, Toronto, Ontario, Canada.
⁶ Canada Centre for Inland Waters, Environment and Climate Change Canada, Burlington, Ontario, Canada.
⁷ Faculty of Chemistry, Biotechnology and Food Sciences (KBM), Norwegian University of Life Sciences (NMBU), NO-1433 As, Norway.
⁸ Institute of Natural Sciences, North-Eastern Federal University, Russia.
⁹ IJRC-PTS-NA, Toronto, Ontario, M2N 6X9, Canada.

Abstract

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.

Keywords: Air-water exchange; Arctic Ocean; Budget; Mass balance model; β-Hexachlorocyclohexane.