干旱区研究2018，Vol.35Issue(2)：277-286,10.DOI:10.13866/j.azr.2018.02.04
东天山哈密榆树沟流域夏季降水的化学特征
Chemical Properties of Summer Precipitation in the Yushugou River Basin in the East Tianshan Mountains
摘要
Abstract
As an effective means to study the change of atmospheric chemical composition, atmospheric precipita-tion chemistry could accurately reflect the local atmospheric environmental quality and air pollution.The precipitati-on chemical properties far away from human colonies can reflect the background value of atmospheric chemistry, and can also help us to study the atmosphere chemical conversion, transmission and the formation process and mecha-nism of acid rain.Restricted by the seasonal precipitation distribution and the observation conditions in drainage ba-sin, the pH value, EC and ion composition in precipitation in the Yushugou River Basin in the east Tianshan Mountains from May to August 2013 were analyzed.The ionic sources were simultaneously investigated.The results showed that precipitation was neutral with mean pH value of 6.8.It suggested that there was no acid rain during the sampling period in the study area.The EC was in a range of 3.79-239 μs·cm-1, and it was obviously affected by precipitation.With the increase of rainfall, the under cloud wash action diluted the conductive ions in precipitation, and the precipitation conductivity decreased correspondingly.The concentrations of cations and anions were in the orders of Ca2+ ＞ NH+4 ＞ Na+ ＞ K+ ＞ Mg2+ and SO2-4 ＞ NO-3 ＞ Cl- ＞F- respectively.The cationic order was exactly the same as that of the elements in crust and different from that of cation concentration in seawater (Na+ ＞Mg2+ ＞ Ca2+ ＞ K+).It may be due to the geographic location.The Yushugou River Basin is located in an arid ar-ea where large deserts are distributed.The SO2-4 /NO-3 ratio (1.76) indicated that SO2-4 was the main acid-causing substance in precipitation.The sources of the different ions in summer precipitation were different.SO2-4, NO-3, F-and NH+4 came mainly from man-made sources, such as coal burning, vehicle emission and agricultural production activities.Cl- almost came from the sea salt source and crust source.The sodium concentration was mainly affected by sea salt, and a quite part of which was from terrigenous sources.Ca2+ and K+ came from the non-sea-salt and affected mainly by the earth surface and human activities.In the study area, there were four water vapor paths in-cluding the northwest, southwest, southeast and north paths.Air mass from the northwest path originated from west Russia and Kazakhstan and passed through west Xinjiang.Water vapor originated from Mongolia passed across west Inner Mongolia with low population density and relatively underdeveloped economy.Human activities were frequent along the northwest path.There were the large deserts with alkaline soil along the northwest and north paths.Large amounts of alkaline substances were carried up to the atmosphere where alkaline substances could neutralize acid rain.Water vapor from the southwest path was from southwest inland of China and passed over the east Qinghai-Ti-bet Plateau. Vegetation in southwest inland grew well and less affected by human activities. Air mass along the southeast path was from the midwest region of China, and the vegetation coverage was very low, so precipitation was greatly influenced by terrigenous sources.关键词
大气降水/化学特征/离子来源/气团轨迹/榆树沟流域/东天山Key words
precipitation/chemical property/ion source/air trajectories/Yushugou River Basin/East Tianshan引用本文复制引用
王晓艳,蒋缠文..东天山哈密榆树沟流域夏季降水的化学特征[J].干旱区研究,2018,35(2):277-286,10.基金项目
国家重大科学研究计划项目(超级973项目) (2013CBA01801) （超级973项目）
陕西省自然科学基础研究计划(2017JQ6080) （2017JQ6080）
陕西省高校科协青年人才托举计划项目(20170303) （20170303）
陕西省教育厅重点项目(17JS038) （17JS038）
渭南市创新团队专项计划(2015TCTD-2)资助 （2015TCTD-2）
