天山东部雪冰中硝酸根浓度对中亚生物质燃烧的响应研究

Influence of Biomass Burning in Central Asia on Nitrate Concentrations in Urumqi Glacier No. 1,Eastern Tianshan Mountains,China

研究了天山东部雪冰中NO 3-浓度对中亚哈萨克斯坦生物质燃烧的响应情况.在天山乌鲁木齐河源1号冰川持续采集了52组表层雪与雪坑样本,分析了雪样中NO 3-等成分的浓度,运用HYSPLIT模型模拟了空气轨迹,目的是考察雪冰中NO 3-与2002年哈萨克斯坦草原大火的关系,探讨由生物质燃烧产生的NO 3-在高海拔山岳冰川雪层中的沉降效应.1号冰川表层雪中的NO 3-可以作为某些典型生物质燃烧的辅助表征物,2002年9月中旬～10月下旬,NO 3-浓度与传统燃烧指示剂K+浓度的相关系数高达0.74,明显高于常年平均值.从哈萨克斯坦的火点传送至1号冰川附近,一般需要2～6 d.携带生物质燃烧产物的气团,能否于1号冰川表层雪中保留信息在很大程度上取决于当地的气温与降水条件.1号冰川在湿季受淋溶作用影响显著,运用冰芯恢复古气候时应充分考虑到后沉积过程的影响.

Influence of biomass burning in Kazakhstan on nitrate concentrations in eastern Tianshan Mountains was studied.52 samples of surface snow and snow pits were collected from Glacier No.l at the headwater of Urumqi River in eastern Tianshan Mountains,China.Nitrate concentrations in these samples were measured and atmospheric transmission was reconstructed with HYSPLIT air trajectory model.The objectives of this study were to identify the relationship between steppes fire and nitrate concentration in snow,and develop deposition process of nitrate caused by biomass burning in alpine glacier at high altitude.Results indicated that nitrate in surface snow could be regarded as a subsidiary indicator of biomass burning for long distance.Correlations for NO 3-and K ＋ were 0.74 from mid September to late October 2002,which was obviously higher than mean concentration.It took 2-6 days from fire spots in Kazakhstan to sampling site.Whether the information in air mass with biomass burning products can be recorded or not,was mostly depend on local temperature and precipitation.Eluviation process was prominent at Glacier No.l in wet season,so postdepositional effect should be considered in paleoclimate reconstruction by ice core.