Spatial Distributions and Seasonal Changes of Current- Use Pesticides from the North Pacific to the Arctic Oceans

摘要

Distributions of eight targeted current-use pesticides (CUPs) chloroneb, simazine, atrazine, alachlor, dacthal, chlorobenzilate, methoxychlor, and permethrin were investigated in seawater and the atmosphere in a region covering the North Pacific to the Arctic Oceans during the 7th and 8th Chinese National Arctic Research Expedition (2016 and 2017) voyages of the research vessel R/V Xuelong (Snow Dragon in English). Total CUP concentrations in seawater have prominent seasonal and latitudinal trends, with higher concentrations occurring at lower latitudes in early summer. The major contributors of the CUPs (Σ_8CUP) did not alter over different seasons with dominant chloroneb, alachlor, and atrazine accounting for more than 90, but their concentrations did have marked seasonal changes. However, the compositions of the eight analyzed CUPs varied indistinctly between seasons indicating a possible combined environmental impact on these compounds rather than the effects of individual chemical properties. Three-day backward air mass trajectories indicate that atmospheric masses from northeastern China are responsible for the high concentrations of CUPs in East China and Japan Seas, whereas those from the North Atlantic Ocean contribute to the low levels in local area. Fugacity ratios indicate potential volatilization and equilibrium of chloroneb in the Canada Basin of the Arctic Ocean and Japan Sea, respectively, and deposition of other CUPs in both regions. However, atmospheric concentrations are decoupled from those in seawater, which indicates a low exchange rate.