摘要
通过连续收集降水样品对祁连山浅山区民乐县大气降水特征及水汽来源进行研究,运用相关分析和主成分因子分析,探讨了2013年5月27日至2014年7月7日祁连山民乐地区降水常量离子的化学特征。结果表明:研究时段内降水离子浓度由大到小依次为Ca^(2+)>SO_4^(2-)>NH_4^+>Cl^->Na^+>NO_3^->Mg^(2+)>K^+,其中Ca^(2+)和SO_4^(2-)是高浓度离子,阳离子总浓度远远高于阴离子总浓度。降水pH平均值为7.44,降水电导率的变化范围为4.0μs·cm^(-1)~940.0μs·cm^(-1),平均值为167.93μs·cm^(-1)。Ca^(2+)离子和SO_4^(2-)离子分别占阳离子和阴离子总浓度的47%和44%。各阴阳离子随季节变化表现出明显的波动趋势,冬、春季节降水极少时阴阳离子浓度较高,而在夏季降水较多时各离子浓度较低。冬春季频繁的沙尘暴活动造成大气陆源气溶胶浓度升高,且该时段降水量少,因此降水离子浓度升高。相关分析和主成分因子分析结果表明,祁连山浅山区民乐县的降水化学离子主要来源于陆源物质,农业生产和人类活动产生的气溶胶是次要来源。
In order to determine the characteristics and sources of the chemical composition of precipitation in Qilian Mountains, Gansu Province, China, a total of 44 precipitation samples were collected from individual precipitation events at the meteorological station of Minle County from May 2013 to July 2014, which located in low coteau of Qilian Mountains. All precipitation samples were analyzed for major cations (Na+, K+, NH4+, Mg2+ and Ca2+), anions (Cl-, NO3- and SO42-), pH and electrical conductivity (Ec) using water chemistry mea- surement with Dionex-600 and Dionex-300. Results show that the average precipitation pH value was 7.44, while the precipitation Ec values ranged from 4.0 μs cm-1 to 940.0 μs cm-1 with an average value of 167.93 μs. cm-1. During the entire sampling period, the concentrations of cations and anions decreased in the order of Ca2+ 〉 SO42- 〉 NH4+ 〉 Cl- 〉 Na+ 〉 NO3- 〉 Mg2+ 〉 K+. The total cation concentrations were greatly higher than the total anion concentrations. Ca2 + is the dominant cation in precipitation with an average value of 624.82 μeq L-1 (0.95-2 061.40 μeq L-1), accounting for 47% of the total cations in precipitation. SO42- is the predominant anion, accounting for 44% of the total anions. Precipitation in low coteau of Qilian Mountains was of Ca2+ and SO42- type. The concentrations of these main ions were relatively high compared to those reported in other regions of Qilian Mountain. Seasonal variations of ions indicate that cation and anion concentrations in summer season were relatively lower. However, the precipitation events show higher cation and anion concentrations during winter and spring. Frequent sand storm in winter and spring resulted in a high concentration of continental atmospheric aerosols, which finally promoted the ion concentrations in these two seasons. Correlation and Main factor analy- sis indicate that regional crustal aerosols and species are the major sources for these ions, agricultural activity and aerosols from human pollution are the secondary sources, and the contribution of sea salt was the least due to the long distance transport. By analyzing the chemical composition of precipitation in different seasons, it is easy to know the variations and sources of precipitation ions during the sampling period. Additionally, it can contribute to analyzing the degree of human survival environment deterioration in low coteau of Qilian Moun- tains in the future.
出处
《干旱区地理》
CSCD
北大核心
2017年第3期573-580,共8页
Arid Land Geography
基金
甘肃省荒漠化与风沙灾害防治重点实验室开放课题基金(GSDC201505)资助
关键词
降水
化学离子
来源
祁连山浅山区
precipitation
chemical ion
environment
Qilian Mountains