高亚洲地区吸光性气溶胶的地球化学过程及其环境影响

Aerosols emitted from anthropogenic activities have more evident impacts on geochemical cycle between atmosphere and cryosphere as well as the regional environment. The relationship between the accelerated melting of glaciers in high Asian regions including Tibet, Pamir and Yungui Plateaus with light-absorbing aerosols like black carbon became a hot topic in current international geoscience research. This study will conduct a three-year's observation at four mountain observation stations in Ranwu, Mushitage, Qinghai Lake, and Yulong Mt. We will obtain the physical, chemical and optical properties of three types of light-absorbing aerosols including black carbon, brown carbon, and mineral dust. The dry deposition velocity of aerosol particle will be measured in the surface of snow-ice. The dry and wet deposition processes and enrichment of light-absorbing aerosols in the snow layers will be recognized. Surface snow samples at four typical sites and snow pit samples at two profiles will be collected in order to develop the relationship between the contents of light-absorbing aerosols and surface albedo. Three types of models including receptor, atmospheric chemistry and radiative forcing models will be utilized to quantify the source contributions, transport routes and environmental effects of these aerosols, which can provide database and positive scientific evidences for the international negotiation about the aerosol and cryosphere as well as the fifth evaluation report of IPCC.

人为活动排放的气溶胶在大气圈及冰雪圈的地球化学循环对区域环境造成的影响日益受到关注，我国西部高亚洲地区（青藏高原、帕米尔、云贵高原）的冰川消融与黑碳等吸光性气溶胶的关系成为当前国际地学研究的热点问题。本研究拟在藏东南然乌、慕士塔格、青海湖、玉龙雪山等4个高山站开展三年观测，获得大气中黑碳、棕碳与粉尘等三类吸光性气溶胶的物理、化学与光学特征，实测气溶胶粒子在冰雪表面的干沉降速度，认识其干湿沉积过程以及沉降到雪层中的后生改造地球化学过程，在4个代表性点采集表层雪样品以及2个站点开展雪坑观测研究，根据这些气溶胶的时空分布特征建立气溶胶含量变化与反照率降低的经验函数，采用受体模式、大气化学模式与辐射模式等，定量认识三类气溶胶的来源贡献、输送过程与环境效应，为我国在有关气溶胶与雪冰的国际谈判中以及IPCC第五次评估报告等提供有利的科学证据。

人为活动排放的气溶胶在大气圈及冰雪圈的地球化学循环对区域环境造成的影响日益受到关注，我国西部高亚洲地区（青藏高原、帕米尔、云贵高原）的冰川消融与黑碳等吸光性气溶胶的关系成为当前国际地学研究的热点问题。本项目获得高原几个站点吸光性气溶胶及其它关键组分的浓度水平和季节分布。获得大气中碳及其它关键气溶胶组分的物理、化学与光学特征，包括黑碳、棕碳及粉尘三类吸光性气溶胶的浓度水平、季节分布、粒径谱、形貌、内外混合方式等理化特征，同时观测了青藏高原大气散射系数、吸收系数、消光系数、单次散射反照率等光学特性；定量认识三类气溶胶的来源贡献、输送过程与环境效应（理解非季风季节和季风季节不同气象条件输送路径、输送与演化特征）。开展了青藏高原黑碳气溶胶特征及其辐射强迫效应研究，采用国际先进的大气动力化学模式 (WRF-Chem)和辐射传输（TUV）等模式，研究黑碳气溶胶区域排放、传输及定量计算吸光性气溶胶的直接气候效应以及对我国西部地区气候环境的影响方面取得一定成果。利用SNICAR雪冰气溶胶辐射评估模式计算得到由黑碳引起的地表反照率、辐射强迫和雪水当量变化，探讨了冰芯记录黑碳变化及其来源和冰雪消融效应。青藏高原不同区域气溶胶粒子的电子显微镜观测表明高海拔高原大气中黑碳颗粒的老化过程可能非常缓慢，在考察其气候和环境效应时，这种独特的现象应该得到更多的关注。项目成果为认识青藏高原冰川消融与黑碳等吸光性气溶胶的关系这一国际地学研究的热点问题提供科学依据。