北山地区大气降水中水化学及稳定同位素特征

为揭示甘肃北山地区大气降水的水化学及同位素特征，利用2012~2019年度采集的97件大气降水样品，采用相关性分析，富集因子，气团后向轨迹分析等多种方法对北山地区稳定同位素变化特征及其影响因素，降水中主要离子变化特征，不同离子来源及贡献，水汽来源进行了分析.结果表明，北山地区区域降水线的斜率与截距均高于张掖地区大气降水线；该区降水中稳定同位素比率明显受季节性，温度和高程效应的影响，在年尺度下，降雨量效应不明显；该区降水中氘盈余变化较大，雨季降水中氘盈余显著小于旱季降水中氘盈余值；北山地区大气降水的水化学型主要为HCO₃·SO₄-Ca和HCO₃-Ca型，降水中离子浓度具有明显的季节性变化，降雨量的增加对离子浓度具有一定的稀释作用；Na⁺受海源和陆源物质的双重影响；绝大部分的Ca²⁺，K⁺，HCO₃^-和部分Mg²⁺来源于陆源，SO₄^2-与NO₃^-的主要来自于人类活动输入；区内冬夏季水汽来源基本一致，来源于西北方向的季风源是北山地区最主要的水汽来源.研究成果可为我国高放废物地质处置库选址和性能评价以及未来地下处置库建设提供依据，也有助于丰富西北干旱区的水文循环过程研究.

Hydrochemical and stable isotope characteristics of precipitation in Beishan Area

For the purpose of reveal the chemical and isotope characteristics of atmospheric precipitation in Beishan Area, Gansu Province, 97 samples collected from 2012~2019 were analyzed. Correlation analysis, enrichment factors, backward trajectory analysis and other methods were used to in this paper. Based on these methods, the variation characteristics and influencing factors of stable isotope, the variation characteristics of main ion, different source contributions for ion concentration, and the sources of water vapor in precipitation were elaborated. The following knowledge and results were obtained. The slope and intercept of the local meteoric water line in Beishan area were higher than that in Zhangye basin. The stable isotope ratio of precipitation in this area was obviously affected by seasonal, temperature and elevation factors. In additional, the precipitation amount effect was not obvious at the annual scale. The deuterium excess (d-excess) in precipitation varied clearly, and the d-excess in rainy season is significantly smaller than that in dry season. The hydrochemical types of precipitation in Beishan area are mainly HCO₃·SO₄-Ca and HCO₃-Ca. The ion concentration in precipitation varied obviously with seasonal, and the increase of precipitation amount has a slightly dilution effect on the ion concentration. Na⁺ is affected by both marine and soil sources. The majority of Ca²⁺, K⁺, HCO₃^-and some Mg²⁺ came from soil sources, and SO₄^2- and NO₃^- mainly came from human activities. The sources of water vapor in winter and summer are nearly same, and the monsoon circulation source from the northwest is the most important. These values can be useful for the selection, safety assessment of the high-level radioactive waste repository and the construction of the final repository in the future. Furthermore, it also can enrich the hydrological cycle research in the arid area of Northwest China.