Distribution and air–sea exchange of organochlorine pesticides in the North Pacific and the Arctic

Abstract

[1] Surface seawater and boundary layer air samples were collected on the icebreaker Xuelong (Snow Dragon) during the Fourth Chinese Arctic Research Expedition (CHINARE2010) cruise in the North Pacific and Arctic Oceans during 2010. Samples were analyzed for organochlorine pesticides (OCPs), including three isomers of hexachlorocyclohexane (HCH), hexachlorobenzene (HCB), and two isomers of heptachlor epoxide. The gaseous total HCH (SHCHs) concentrations were approximately four times lower (average 12.0 pg m À3 ) than those measured during CHINARE2008 (average 51.4 pg m À3 ), but were comparable to those measured during CHINARE2003 (average 13.4 pg m À3 ) in the same study area. These changes are consistent with the evident retreat of sea ice coverage from 2003 to 2008 and increase of sea ice coverage from 2008 to 2009 and 2010. Gaseous b-HCH concentrations in the atmosphere were typically below the method detection limit, consistent with the expectation that ocean currents provide the main transport pathway for b-HCH into the Arctic. The concentrations of all dissolved HCH isomers in seawater increase with increasing latitude, and levels of dissolved HCB also increase (from 5.7 to 7.1 pg L À1 ) at high latitudes (above 73 N). These results illustrate the role of cold condensation processes in the transport of OCPs. The observed air-sea gas exchange gradients in the Arctic Ocean mainly favored net deposition of OCPs, with the exception of those for b-HCH, which favored volatilization.

Concentrations and Water Mass Transport of Legacy POPs in the Arctic Ocean

“…Similar to α‐HCH, higher concentrations were present in the Barrow Strait (9.4 pg/L) than lake water samples in the area (average: 2.8 ± 1.6 pg/L). These results were comparable to those observed in the North Pacific, North Atlantic, and Arctic Oceans (Table S9) (Barber et al, ; Cai et al, ; Lohmann et al, ; Wong et al, ).…”

“…A wealth of studies has described the occurrence of legacy organic pollutants in open ocean seawater (Cai et al, 2012;Carrizo & Gustafsson, 2011a;Gioia et al, 2008;Iwata et al, 1993;Lohmann et al, 2009). Their presence in deep ocean waters lacks data, due to the logistical challenges in sampling, although the transfer to the deep ocean environment is considered one of the long-term global sinks for POPs (Dachs et al, 2002).…”

Selected current‐use and historic‐use pesticides in air and seawater of the Bohai and Yellow Seas, China

“…Cai et al . [] reported that air‐water exchange of α‐HCH was near equilibrium in the western North Pacific and western Arctic Ocean in 2010 except that net volatilization appeared near the East Asian continents due to higher dissolved concentrations. α‐HCH was also close to equilibrium in the German Bight (North Sea) in May (mean FR: 2.5 ± 1.3), but significant riverine inputs and stronger volatilization of α‐HCH from local surface combining polluted air masses, respectively, resulted in slightly lower FR values in March and higher FR values in July (mean FR: 0.87 ± 0.97 for March, 3.4 ± 2.1 for July) [ Zhong et al ., ].…”

“…HCB was also undergoing net volatilization or was close to equilibrium in Atlantic [ Lohmann et al ., ]. HCB was near equilibrium in the open Pacific [ Zhang and Lohmann , ] and was net deposition or near equilibrium in the North Pacific, North Atlantic, and Arctic [ Cai et al ., ; Lohmann et al ., ]. Overall, the FR values obtained by these works varied within a narrow range from 0.2 to 6.…”

Organochlorine pesticide residues in surface water from Sichuan Basin to Aba Prefecture profile, east of the Tibetan Plateau

“…Drins were never industrially produced or used as agricultural pesticides in China (Lammel et al, 2007;Zhang et al, 2012). However, recent studies have indicated that dicofol (Qiu et al, 2005;Chen et al, 2008), lindane (Xing et al, 2010;Cai et al, 2012) and chlordane (Li et al, 2008;Zhang et al, 2012) are still used in China. On the other hand, many contaminants came from historical OCP residues (Xing et al, 2009;Wang et al, 2012;Yang et al, 2013).…”