Department of Earth Science, Memorial University of Newfoundland , St. John's, NL Canada.
Air Quality Science Division, Environment Canada , Dartmouth, NS Canada.
Environ Sci Technol. 2015 Oct 20;49(20):12120-6. doi: 10.1021/acs.est.5b01589. Epub 2015 Oct 6.
Mercury (Hg) is an important environmental contaminant, due to its neurotoxicity and ability to bioaccumulate. The Arctic is a mercury-sensitive region, where organisms can accumulate high Hg concentrations. Snowpack mercury photoredox reactions may control how much Hg is transported with melting Arctic snow. This work aimed to (1) determine the significance of temperature combined with UV irradiation intensity and snow age on Hg(0) flux from Arctic snow and (2) elucidate the effect of temperature on snowpack Hg photoreduction kinetics. Using a Teflon flux chamber, snow temperature, UV irradiation, and snow age were found to significantly influence Hg(0) flux from Arctic snow. Cross-correlation analysis results suggest that UV radiation has a direct effect on Hg(0)flux, while temperature may indirectly influence flux. Laboratory experiments determined that temperature influenced Hg photoreduction kinetics when snow approached the melting point (>-2 °C), where the pseudo-first-order reduction rate constant, k, decreased twofold, and the photoreduced Hg amount, Hg(II)red, increased 10-fold. This suggests that temperature influences Hg photoreduction kinetics indirectly, likely by altering the solid:liquid water ratio. These results imply that large mass transfers of Hg from snow to air may take place during the Arctic snowmelt period, altering photoreducible Hg retention and transport with snow meltwater.
汞（Hg）是一种重要的环境污染物，因为它具有神经毒性和生物累积能力。北极是一个对汞敏感的地区，那里的生物体可以积累高浓度的汞。积雪中汞的光还原反应可能控制着随着北极融雪而迁移的汞的量。本研究旨在：（1）确定温度结合紫外线辐射强度和雪龄对北极雪中 Hg(0)通量的重要性；（2）阐明温度对雪层 Hg 光还原动力学的影响。使用特氟隆通量室，发现雪温、紫外线辐射和雪龄显著影响北极雪中 Hg(0)通量。互相关分析结果表明，紫外线辐射对 Hg(0)通量有直接影响，而温度可能通过间接影响通量。实验室实验确定，当雪接近融点（>-2°C）时，温度会影响 Hg 光还原动力学，此时准一级还原速率常数 k 降低了两倍，光还原的 Hg 量 Hg(II)red 增加了 10 倍。这表明温度通过改变固-液水比间接影响 Hg 光还原动力学。这些结果表明，在北极融雪期间，大量的 Hg 可能会从雪中转移到空气中，从而改变光还原 Hg 的保留和随融雪水的迁移。
