陕北黄土区大气降水同位素特征及其水汽来源  

Isotopic characteristics and vapor sources of atmospheric precipitation in the loess region of North Shaanxi,China

作　　者：李佳奇 黄亚楠[1] 石培君 李志[1] LI Jia-qi;HUANG Ya-nan;SHI Pei-jun;LI Zhi(College of Natural Resources and Environment,Northwest A&F University,Yangling 712100,Shaanxi,China)

机构地区：[1]西北农林科技大学资源环境学院,陕西杨凌712100

出　　处：《应用生态学报》2022年第6期1459-1465,共7页Chinese Journal of Applied Ecology

基　　金：国家自然科学基金项目(42071043);中央高校基本科研业务费专项资金(2452020002)资助。

摘　　要：为探究陕北黄土区大气降水氢氧稳定同位素特征及其水汽来源,以陕西省定边县为研究区,于2018—2020年共收集107次降水事件样品,分析了该区降水中δ^(18)O和δ^(2)H组成特征,并探讨了不同季节的水汽来源。结果表明:定边氢氧稳定同位素存在明显的季节变化,湿季(6—9月)偏贫化,干季(4—5月、10—11月)偏富集;氘盈余呈现干季高湿季低的特点。当地大气降水线方程为δ^(2)H=7.35δ^(18)O+4.19(R^(2)=0.96,P<0.01),斜率和截距均小于全球大气降水线,表明该区域降水受到一定程度的蒸发分馏影响。全年降水同位素组成表现出温度效应,而湿季和干季差异较大,仅干季存在温度效应,湿季降水同位素组成可能受温度和降水量的共同影响。HYSPLIT气团轨迹模型表明,干季水汽主要来自大西洋和极地北冰洋地区,而湿季降水主要来自印度洋和太平洋,同时受到西风带的影响。To explore the hydrogen and oxygen stable isotopes and vapor sources of atmospheric precipitation in the loess region of north Shaanxi,we collected 107 samples of precipitation during 2018 to 2020 in the Dingbian County,Shaanxi Province.After measuringδ^(18)O andδ~2H of precipitation,we analyzed the isotopic characteristics and vapor sources of precipitation in different seasons.There was obvious seasonal variability inδ^(18)O andδ~2H,in that they were more depleted in the wet season(June-September)but more enriched in the dry season(April-May,October-November).In addition,the deuterium excess values were high in the dry season but low in the wet season.The local meteoric water line was regressed asδ~2H=7.35δ^(18)O+4.19(R^(2)=0.96,P<0.01)with slope and intercept lower than that of the global meteoric water line,indicating an impact of evaporation on isotope fractionation.There was temperature effect in the precipitation isotopes for the whole year and for the dry season,while the precipitation isotopes in the wet season were affected by the combined effects of temperature and rainfall amount.The HYSPLIT model showed that the dry season water vapor mainly came from the Atlantic Ocean and the polar Arctic Ocean,while the wet season vapor mainly came from the Indian Ocean and Pacific subject to the Westerly.

关 键 词：黄土区 氢氧稳定同位素 环境因素 HYSPLIT 水汽来源 

分 类 号：P426[天文地球—大气科学及气象学]