天山东部典型地区雪冰中含氮化合物记录过程及其环境意义研究

雪冰 含氮离子 气溶胶 天山 全球变化
张明军 2008-01 项目
【英文摘要】Nitrogen cycle is an important part of global change research, and record process and its environmental significance of nitrogen-containing compounds in snow and ice is one of the vital topics in cryospheric sciences. Based on the observation network of Tianshan Glaciological Station, transformation of major nitrogen-containing ions (nitrate and ammonium) in aerosol-snow-ice process is analyzed systemically, with long-term atmospheric aerosol and snow pit samples collected at three typical glaciers (Glacier No.1 at the headwaters of Urumqi River, Glacier No.51 at Haxilegen of Kuytun River and Miaoergou Flat-topped Glacier). Seasonality is displayed for nitrate and ammonium concentration in both aerosol and surface snow of Glacier No.1 at the headwaters of Urumqi River. Correlation between concentrations in aerosol and surface snow for nitrate is much higher in the wet seasons than that in the dry seasons, while correlation for ammonium is opposite from nitrate. The vertical concentration profile of major nitrogen-containing ions is influenced significantly by post-depositional process (especially for elution effect in the wet season), and the upper section of snowpack is affected more strongly than the bottom section. With a great loss for concentration-peak spacings and flux, environmental records at the upper section of snowpack are kept into ice. The mean concentration of nitrate in snowpack increases from west to east, and the concentration order of ammonium is Glacier No.51 at Haxilegen of Kuytun River < Miaoergou Flat-topped Glacier < Glacier No.1 at the headwaters of Urumqi River. The spatial distribution of nitrogen-containing ions is influenced by long-distance atmospheric dust, local anthropogenic output from industry and agriculture activities, and the sampling conditions.
【中文摘要】氮循环是全球变化研究的重要领域之一,雪冰中含氮物质的记录过程及其环境意义的讨论更是全球雪冰研究的热点之一。本项目以新疆天山冰川国家野外科学观测研究站的观测网络为依托,选取乌鲁木齐河源1号冰川、奎屯河哈希勒根51号冰川与庙尔沟平顶冰川,在多年观测研究与资料积累的基础上,通过大气气溶胶与雪坑样品,系统地探讨了天山东部典型冰川区气-雪-冰界面上主要含氮离子(硝酸根与铵根)的记录过程及环境意义。乌鲁木齐河源1号冰川积累区上方大气气溶胶与表层雪中含氮离子浓度均呈现出明显的季节变化,气-雪间硝酸根浓度在干季显著相关,而铵根则在湿季相关性较好。以夏季淋溶作用为主的后沉积过程可以明显改造雪层中硝酸根与铵根的浓度剖面,且雪层上部变化强烈,下部相对稳定。冰芯记录下的环境信息是经过长期淋溶改造后较为稳定的信息,浓度峰间距与通量都明显减小。三个典型冰川区同期雪坑样品中硝酸根浓度表现出自西向东升高的趋势,而铵根则为哈希勒根51号冰川<庙尔沟平顶冰川<乌鲁木齐河源1号冰川,这种空间分布格局受远源沙漠粉尘传输、近源工农业生产与生活排放以及积累区采样点环境差异的共同影响。