[Stable Isotope Characteristics and Vapor Source of Precipitation in the South and North Slopes of Wushaoling Mountain].

We analyze the stable isotope characteristics and vapor source of precipitation in a monsoon marginal area in the southern and northern slopes of Wushaoling Mountain, northwestern China, using 97 precipitation samples collected from October 2016 to October 2017. Correlation analysis and HYSPLIT model are used to study the characteristics of stable isotopes in precipitation, local meteoric water line equation, temperature and precipitation effects, and vapor source. The study found the following results. ① The slope and intercept of the southern slope local meteoric water line were lower than of those of the northern slope and global averages. ② Although the isotope temperature effects and seasonal effects of both slopes were obvious, the temperature effect of the northern slope was more obvious than of that of the southern slope. ③ The stable isotopes of precipitation during the summer on the northern slope and the precipitation on the southern slope<5 mm revealed that the precipitation effect was weak. There was no obvious precipitation effect in other seasons or in other precipitation levels on both slopes. ④ Vapor from the northwest and north accounted for>90% of the total. The northern slope was rarely affected by monsoon vapor, but the southern slope was affected by the southeast monsoon during the summer. Local water vapor recycling contributed to water vapor in the southern and northern slopes of Wushaoling Mountain. This study could improve the cognition of precipitation isotopic evolution in alpine regions, and lays a foundation for further research on isotope hydrology in cold and arid regions.

[Hydrochemical Characteristics and Sources of Ions in Precipitation at the East Qilian Mountains].

Precipitation of the northwest China is different from that in other regions of China. The vapor reaches this region after long distance transportation with little precipitation, and the ratio of precipitation variation is large. Wushaoling at the east Qilian Mountains is an important divided line of climate in China. The east region of it is affected by South Asia and East Asia monsoon, while the west region of it is influenced by Westerly circulation. So ion combinations in precipitation are complex for the trajectories of water vapor transportation, the natural environments and the development levels of social and economy in different regions. Precipitation samples were collected at Heisongyi located at the east Qilian Mountains. Hydrochemical characteristics and sources of ions were analyzed by factor analysis, Enrichment factor analysis and back trajectory analysis. EC values in precipitation ranged from 29.20 to 892.00 µS·cm-1, which were controlled by alkaline element. The precipitation was weak alkaline with pH values ranging from 7.02 to 8.89. EC values in precipitation were higher in autumn and winter than in spring and summer, opposite to pH values. The type of precipitation was SO42--Ca2+ for the cation concentrations following the order of Ca2+ >Mg2+ >Na+ >NH4+ >K+ and the anion concentrations following the order of SO42- >Cl- >NO3-. The concentrations of K+, Mg2+, Ca2+, NH4+, Cl-, NO3- and SO42- were the highest in autumn, but the peak value of Na+ concentration appeared in winter. As a whole, ion concentrations were higher in autumn and winter than in spring and summer. Enrichment factor indicated that Na+and Cl- mainly came from marine source but Na+ partly originated from crust source in winter and Cl- partly originated from anthropogenic source in winter, and that K+, Mg2+ and Ca2+ mainly came from crust source except that Mg2+ partly originated from anthropogenic source in winter, and that NO3- and SO42- mainly came from anthropogenic source. The trajectories of water vapor transportation from directions of northwest, north, north with southeast, northwest with southeast, northwest with southwest, northwest with north and southeast were ion original sources in precipitation, and the major trajectory came from northwest direction. Among these trajectories of water vapor transportation, that from northwest, north and north with southeast appeared in each season, but that from northwest with southeast appeared in spring and summer, that from northwest with southwest and northwest and north with southeast appeared in summer. Though ions originated from marine transport by Westerly and monsoon, from crust provided by desert and Gobi in central Asia, Xingjiang and Mongolian plateau, and from humanity activity related to cities pollution and industrial and agriculture production of oasis at all trajectories, the concentrations of ions in precipitation were effected by the strong and weak variations of different weather systems.

[Analysis on chemical compositions of rainwater in summer, Lijiang City, China].

Rainwater samples were colleted from Lijiang City, China, in 23 May-2 July, 2006. Rainwater chemical compositions and sources were studied, using HYSPLIT model, ions tracer techniques, correlation and trend analysis. Total ionic concentration was dominated by SO4(2-) and Ca2+, which account for 65.5% and 15.6% respectively. Sort order of ions concentration is SO4(2-) > Ca2+ > Cl(-) > NO3(-) > Na+ > K+ > Mg2+. Total anions concentration is higher than total cations concentration in 13 rainwater events. The ratio of SO4(2-) to NO3(-) varies from 7.2 to 37.1 and average value is 15.7, it reflected SO4(2-) made great contribution to rainwater acidity in Lijiang City. The correlation among ions is significant due to the atmospheric chemical process and similar ionic sources, and correlation coefficient between SO4(2-) and NO3(-) is 0.74. And what's more, the negative correlation of ionic concentration, precipitation and the average wind speed is also outstanding. The source of NO3(-), SO4(2-), K+ and Ca2+ is mainly land dust, and the non-marine source percent of NO3(-), SO4(2-), K+, Ca2+, Mg2+ and Cl(-) is 100%, 98.8%, 96%, 99.3%, 46.7% and 50.3%, respectively. The main reason of atmospheric environmental variation in Lijing City is pollution caused by economic actions. The pollutants from surrounding industrial parks input into Lijiang City by local circulation, and from industrial regions of Southern Asia, Southeastern Asia and Southeastern China input into Lijiang City by monsoonal circulation.