SGER: Snow Chemical Composition and Its Relation to Arctic Springtime Mercury Deposition and Ozone Depletion

这项研究将涉及在臭氧消耗事件（ODE）和汞沉积事件（MDE）发生的关键春季期间，对阿拉斯加北部的雪进行系统采样。人们早就知道，在北纬高纬度地区日出时，会发生不寻常的化学反应，其中涉及溴的化学反应会导致边界层臭氧破坏和汞的沉积。溴的详细来源和确切的化学机制仍在研究中。汞的沉积是一种潜在的环境危害，因此了解过程的细节是很重要的。本研究将尝试量化汞沉积和卤素丰度与海洋源区距离、气象和其他因素的功能依赖关系。该项目利用巴罗北极汞研究（BAMS）的存在，该研究将在阿拉斯加巴罗提供基础设施和详细的化学和物理测量，并将通过巴罗南部和西部地区的雪的地理采样来扩展巴罗北极汞研究。此外，卫星对一氧化溴的观测将用于跟踪臭氧消耗事件的演变，并帮助规划积雪采样期。积雪样本将沿着巴罗、温赖特和阿特卡苏克之间的三条横断面采集。这三个村庄形成一个三角形，腿长约100公里。巴罗和温赖特位于北冰洋岸边，而阿特库苏克则位于内陆。有关臭氧损耗和汞沉积的化学作用受到雪中溴化物离子可得性的限制的假设，将通过本实验得到严格检验。研究将在日出之后进行，但在臭氧消耗活跃期之前，在消耗化学非常活跃的春分附近，以及在臭氧消耗结束但地面上仍有雪的春末。将对雪进行大量采样，包括汞、离子和水的氘和氧同位素组成。这些测量将使目标数量（汞和溴化物）以及物种得以量化，这将有助于将不同地点的特定雪层联系起来。该项目将增进对汞沉积机制的了解，并有利于受这一春季现象影响地区的居民。将研究该地区汞沉积的空间范围和强度。这将有助于更好地了解全球汞预算。该预算将为研究生提供支持，而pi计划在研究区域的三个偏远村庄进行研究报告，从而提高公众对相关问题的理解。

This study will involve the systematic sampling of snow in northern Alaska during the critical springtime period when ozone depletion events (ODE) and mercury deposition events (MDE) take place. It has been known for sometime that unusual chemistry takes place during sunrise at high northern latitudes, in which chemistry involving bromine leads to boundary layer ozone destruction, and deposition of mercury. The details of the source of the bromine and the exact chemical mechanisms are still under study. The deposition of mercury is a potential environmental hazard, and thus it is important to understand the details of the processes. This study will attempt to quantify the functional dependence of mercury deposition and halogen abundance on distance from the ocean source region, meteorology, and other factors. This project leverages the existence of the Barrow Arctic Mercury Study (BAMS) that will provide infrastructure and detailed chemical and physical measurements at Barrow, Alaska, and will extend BAMS through geographical sampling of snow in the region south and west of Barrow. In addition, satellite observations of bromine monoxide (BrO) will be used to track the evolution of ozone depletion events and to help plan the snow sampling periods.The snow samples will be collected along three transects between Barrow, Wainwright, and Atqasuk. The three villages form a triangle with legs approximately 100 km long. Barrow and Wainwright sit on the shore of the Arctic Ocean, while Atqusuk lies inland. The hypothesis that the chemistry responsible for ozone depletion and mercury deposition is limited by availability of bromide ion in the snow will be rigorously tested by this experiment. Studies will be performed after sunrise, but well before the active ozone depletion period, near equinox when depletion chemistry is very active, and late in the spring when ozone depletion has ended but snow remains on the ground. The snow will be sampled for a number of quantities including mercury, ions and the deuterium and oxygen isotopic composition of water. These measurements will allow the quantification of the target quantities (mercury and bromide) as well as species that will aid in correlating specific snow layers at the different sites.This project will improve understanding of the mechanism of mercury deposition and be of benefit to the inhabitants of regions impacted by this springtime phenomenon. The spatial extent and intensity of mercury deposition will be studied in the region. This will lead to better understanding of the global mercury budget. The budget provides graduate student support, and the PIs intend to make presentations on their research at the three remote villages bounding the study region, thereby improving public understanding of the relevant issues.