Isotopic composition of precipitation over Arid Northwestern China and its implications for the water vapor origin

Abstract

In order to reveal the characteristics and climatic controls on the stable isotopic composition of precipitation over Arid Northwestern China, eight stations have been selected from Chinese Network of Isotopes in Precipitation (CHNIP). During the year 2005 and 2006, monthly precipitation samples have been collected and analyzed for the composition of δD and δ 18 O. The established local meteoric water line δD=7.42δ 18 O+1.38, based on the 95 obtained monthly composite samples, could be treated as isotopic input function across the region. The deviations of slope and intercept from the Global Meteoric Water Line indicated the specific regional meteorological conditions. The monthly δ 18 O values were characterized by a positive correlation with surface air temperature (δ 18 O (‰) =0.33 T (℃)-13.12). The amount effect visualized during summer period (δ 18 O (‰) = -0.04P (mm)-3.44) though not appeared at a whole yearly-scale. Spatial distributions of δ 18 O have properly portrayed the atmospheric circulation background in each month over Arid Northwestern China. The quantitative simulation of δ 18 O, which involved a Rayleigh fractionation and a kinetic fractionation, demonstrated that the latter one was the dominating function of condensation of raindrops. Furthermore, the raindrop suffered a re-evaporation during falling processes, and the precipitation vapor might have been mixed with a quantity of local recycled water vapor. Multiple linear regression equations and a δ 18 O-T relation have been gained by using meteorological parameters and δ 18 O data to evaluate physical controls on the long-term data. The established δ 18 O-T relation, which has been based on the present-day precipitation, could be considered as a first step of quantitatively reconstructing the historical environmental climate.

Identifying Groundwater Recharge Sites through Environmental Stable Isotopes in an Alluvial Aquifer

“…The monitored altitude ranges between 1660 and 2703 mamsl, and there is not a relation found between the δ O and altitude. Other geographical parameters such as the longitude or latitude can affect the relation with the δ O, which is consistent with what was reported by Liu et al [36].…”

Stable isotopic compositions of precipitation in China

“…Thus, a substantial part of the precipitation is from local recycled vapour. The d-values for surface water bodies are rather high in the arid regions, which means that the vapour evaporates from them is also high in isotope content (Zhang and Yao, 1998;Liu et al, 2009;Pang et al, 2011). Additionally, the partial evaporation of falling raindrops through the dry atmosphere beneath the cloud further aggravates the depletion of light isotopes.…”

Factors controlling stable isotope composition of precipitation in arid conditions: an observation network in the Tianshan Mountains, central Asia

“…In 2004, a nationwide network named CHNIP (China Network of Isotopes in Precipitation) was established, and the Fukang station (87856?E, 44817?N, 460 m a.s.l.) was selected on the northern slope (Liu et al, 2009(Liu et al, , 2014. In addition, precipitation at stations located in the upper and middle reaches of the Urumqi River basin was also discontinuously sampled since the mid-1990s (Yao et al, 1999;Pang et al, 2011;Feng et al, 2013).…”