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

这项研究将涉及在发生臭氧消耗事件(ODE)和汞沉积事件(MDE)的关键春季期间对阿拉斯加北部的雪进行系统采样。众所周知，北方高纬度地区的日出时会发生不寻常的化学作用，其中涉及溴的化学作用会导致边界层臭氧破坏和汞沉积。溴的来源和确切的化学机制的细节仍在研究中。汞的沉积是一种潜在的环境危害，因此了解这些过程的细节是很重要的。这项研究将试图量化汞沉积和卤素丰度与距离海洋源区的距离、气象和其他因素的函数依赖关系。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州巴罗提供基础设施和详细的化学和物理测量，并将通过对巴罗南部和西部地区的雪进行地理采样来扩展BAMS。此外，还将利用对溴一氧化碳的卫星观测来跟踪臭氧消耗事件的演变，并帮助规划雪样采样周期。雪样将沿巴罗、温赖特和阿特卡苏克之间的三个横断面采集。这三个村庄形成一个三角形，腿长约100公里。巴罗和温赖特坐落在北冰洋的海岸上，而阿特库苏克则位于内陆。这项实验将严格检验导致臭氧消耗和汞沉积的化学物质受到雪中溴离子有效性限制的假设。研究将在日出之后进行，但在臭氧消耗活跃时期之前很久，接近春分时消耗化学非常活跃，在春天晚些时候臭氧消耗已经结束，但地面上仍有雪。将对雪进行一些数量的采样，包括汞、离子以及水中的氚和氧同位素组成。这些测量将能够量化目标数量(汞和溴)以及有助于将不同地点的特定雪层关联起来的物种。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的地区的居民。将研究该区域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。预算提供研究生支持，私人投资机构打算在研究区域周围的三个偏远村庄介绍他们的研究情况，从而提高公众对相关问题的了解。

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.