Occurrence, distribution, and sea-air fluxes of volatile halocarbons in the upper ocean off the northern Antarctic Peninsula in summer
Occurrence, distribution, and sea-air fluxes of volatile halocarbons in the upper ocean off the northern Antarctic Peninsula in summer
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夏季南极半岛北部上层海洋挥发性卤化碳的存在、分布及海气通量
DOI：
10.1016/j.scitotenv.2020.143947
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发表时间：
2020
影响因子：
9.8
通讯作者：
Lu Liu
中科院分区：
文献类型：
--
作者：
Cheng-Xuan Li;Kan Chen;Xia Sun;Bao-Dong Wang;Gui-Peng Yang;Yan Li;Lu Liu
研究了碘甲烷（CH_3 I）、氯仿（CHCl_3）、四氯乙烯（C_2Cl_4）、溴二氯甲烷（CHBrCl_2）、二溴甲烷（CH_2Br_2）和四氯化碳（CCl_4）等6种挥发性卤代烃（VHC）的空间变异。以及影响北方南极半岛（NAP）外上层海洋（0-500 m）VHCs循环的环境因素在2018年夏天。海洋上层生物VHC总量的5%~ 10%聚集在高叶绿素含量的组合层中。然而，更高的VHCs水平观察到的dictionary层（DL）相比，AL，因为保存从冬季和生产的甲藻和绿藻。由于夏季尖的季节性密度跃层和厚的永久性密度跃层的共存，DL可能是上层水体中重要的VHCs储集层。由于海冰和冰川的融化，海水盐度的降低是造成这一现象的原因。50%的变化，在CH 2Br 2和CCl 4的浓度，这对应于增加的CH 2Br 2和CCl 4浓度在较低的盐水质量。结果表明，表层水体中人为污染物CCl 4的平均浓度为44.9 pmol/L，且CCl 4与CHCl 3之间存在较强的正相关关系，表明二者在人为污染物输送过程中具有相似的来源。计算得到的夏季CCl 4、C2Cl 4、CHBrCl 2和CH 2Br 2的海-气通量平均值分别为478.7、93.7、33.7和61.8 nmol/（m2·d），表明NAP外沃茨是大气中VHCs的重要来源，对南极臭氧层的破坏具有潜在的不利影响。
We studied the spatial variations of six volatile halocarbons (VHCs), namely, iodomethane (CH3I), chloroform (CHCl3), tetrachloroethylene (C2Cl4), bromodichloromethane (CHBrCl2), dibromomethane (CH2Br2), and carbon tetrachloride (CCl4), and the environmental influencing factors involved in the cycling of VHCs in the upper ocean (0–500 m) off the Northern Antarctic Peninsula (NAP) during the summer of 2018. About 5%–10% of the total biogenic VHCs in the upper ocean were accumulated in the assemblage layer (AL) with high chlorophylla. However, higher VHCs levels were observed in the dicothermal layer (DL) compared with the AL because of the preservation from winter and production from dinoflagellates and chlorophytes. Owing to the co-existence occurrence of sharp seasonal pycnocline and thick permanent pycnocline, DL could be an important VHCs reservoir in the upper water column during summer. In response to melting of sea ice and glacier, decreased salinity was responsible for ca. 50% of the variation in the CH2Br2and CCl4concentrations, which corresponded with increased CH2Br2and CCl4concentrations in the less saline water mass. Anthropogenic CCl4was found with an average concentration of 44.9 pmol/L, and there was a strong positive relationship between CCl4and CHCl3in the upper water, indicating their similar source of pollutant transport caused by anthropogenic activities. Calculated sea-to-air fluxes of CCl4, C2Cl4, CHBrCl2, and CH2Br2averaged 478.7, 93.7, 33.7, and 61.8 nmol/(m2·d) in summer, respectively, indicating that the waters off the NAP are important sources of VHCs for the atmosphere and exert potentially adverse impacts on the Antarctica ozone depletion.