银川地区降水氢氧同位素变化规律分析

大气降水是区域水循环中重要环节,对于研究区域内水分循环、水分来源、水分转换等水文过程有重要意义.通过对银川地区降水中氢氧同位素特征随月降水量变化趋势进行分析,得出不同季节的降水水汽来源是影响银川地区降水同位素变化的主要因素,秋冬季节降水水汽主要来自于北冰洋地区,春夏季节降水水汽主要来源于印度洋、孟加拉湾及太平洋地区.区域内蒸发的水汽对降水的贡献及降水过程中的二次蒸发作用都使降水中重同位素富集.全年来看,银川地区降雨量效应不明显,但是夏季降雨量对降水中氢氧稳定同位素变化影响不容忽视.通过分析氘过量参数d随月平均降水量的变化趋势,辅助论证了不同季节不同水汽来源的降水是影响氢氧同位素变化的主要因素.     

长江干流径流同位素同步监测

基于2003年1月长江干流径流同位素同步监测资料,分析了径流同位素与大气降水同位素18O和D相对丰度之间的关系,探讨了18O相对丰度和氘盈余(Ed)的空间变化规律.分析结果表明:长江干流径流同位素时程变化主要受降水同位素季节变化的影响;区域降水同位素场是长江干流径流同位素18O和D相对丰度空间变化的主要影响因素;长江流域湖泊或水库蒸发效应是导致长江干流径流重同位素沿程富集的主要因素之一;监测期间长江流域上中游蒸发较为强烈,中游区蒸发最强烈,下游区蒸发变化剧烈.     

植被截留对降水同位素分布的试验研究

植被截留对于探究小流域降雨空间变化原因以及深入理解产流机制具有重要的意义.本文通过对长江中下游小流域梅雨降水事件的林外降水和贯穿降水水样的稳定同位素(δ~(18)O和δ~2H)进行分析,探究贯穿降水同位素时空变化原因.通过拟合林外降水的δ~(18)O和δ~2H得到和睦桥流域梅雨事件大气降水线,其斜率和截距接近全球大气水线,但与中国东部季风区的大气水线存在明显的差别,主要是受采样方法、下垫面条件、气候环境和降水类型的综合作用.降水事件中的贯穿降水比林外降水的氘盈余平均值高,这可能与植被的截留以及强烈的蒸发有关.林外降水和贯穿降水的稳定同位素在时间尺度上的变化存在着明显的不同,总的来说贯穿降水相对更加贫化,这可能由蒸发分馏和雨强共同影响.贯穿降水的同位素展示明显的空间变化,主要由植物截留以及流域地形共同影响.     

阿拉善地区降水同位素特征与水汽来源

基于2013—2015年阿拉善高原阿右旗的降水氢氧稳定同位素组成数据,分析阿拉善高原降水δD和δ~(18)O的特征与变化规律,揭示当地的水汽来源与迁移路径。结果表明:(a)阿拉善高原降水δD和δ~(18)O的变化呈现明显的季节特征,即夏季偏高,冬季偏低。(b)主要气象参数(降水量、气温、大气湿度和风速)中,气温是控制阿拉善高原降水δD和δ~(18)O的主导因素;通过与周边区域的比较,阿拉善高原当地大气降水线的斜率和截距较低,这是由阿拉善高原降水受到非平衡蒸发作用强烈所致;(c)HYSPLIT气团轨迹模型模拟和降水同位素分析揭示了阿拉善高原阿右旗降水主要来自西风和极低气团。     

干旱半干旱荒漠化草原区降水-地表水-地下水同位素分布特征——以达尔罕茂明安联合旗为例

为能揭示出研究尚处于初级阶段的干旱半干旱荒漠化草原区水循环机理,本文应用被视为水体“DNA”探索的同位素示踪方法,对以达尔罕茂明安联合旗为例的干旱半干旱荒漠化草原区所采集的降水、地表水和地下水中同位素含量的时空分布特征进行探究。根据降水氢氧同位素含量及其氘盈余(d)值的变化过程,发现研究区大气降水水汽在夏季主要受海洋季风的影响、冬季主要受蒙古高压影响,而且从时空变化来看研究区地表水和地下水同位素含量随时间变化不大但由于纬度和降水源区不同的影响随着自西向东的空间变化各水体同位素含量逐渐变大。此外,研究区地表水和地下水同位素含量均散落于当地大气降水方程线下方,说明研究区域内地表水和地下水的补给来源主要为降水,并且部分区域地表水与地下水同位素含量分布比较集中,属于交叉分布,说明这些区域还存在地表水和地下水转换互补。     

基于组合赋权法的广安市地源热泵适宜性分区

基于全球大气降水稳定同位素观测网络(GNIP)和国内已有研究黄土高原降水稳定同位素数据,分析黄土高原降水同位素的时空分布特征及其环境效应;通过回归分析建立局地大气降水线方程,同时运用HYSPLIT模型模拟各站点的气团移动轨迹。结果表明：具有明显季节性变化规律,时间上主要表现为春夏季富集、秋冬季贫化;空间上加权平均则呈现出由西北向东南减小的趋势。降水值与温度呈正相关,即存在温度效应,但不存在降水量效应;高程效应的定量关系为高度每增加100m,值减少0.08‰。轨迹模拟结果表明该区的水汽来源在春夏季主要包括大部分东南季风水汽和部分西风带水汽,秋冬季主要以西风带水汽为主。     

延安市城区大气污染特征及影响因素

根据延安市城区2003—2004年间大气污染物浓度资料,应用统计的方法分析了大气中主要污染物二氧化硫、二氧化氮、可吸入颗粒物随季节变化,日时间变化和空间变化的污染特征,并分析了风向、风速、降水、云量、浮尘、逆温等气象因素以及城区地形和人为因素对城区污染物浓度变化的影响.结果表明:延安市城区大气污染状况存在着显著的季节差异和地域性差异,日大气污染呈现明显的双峰特征.风和降水是影响大气污染程度的主要气象因子.     

福建玉华洞降水、滴水和新生碳酸盐δ~(18)O传递及环境意义

为探究福建玉华洞石笋δ18O的气候环境指示意义,于2011年7月~2013年12月,在将乐县天阶山逐月采集大气降水以及玉华洞3个滴水点和相对应的3个新生碳酸盐沉积物的样品,并进行氢氧同位素测试,分析δ18O在大气降水—洞内滴水—新生沉积物的传递过程及其变化规律.结果表明:3个滴水点的δD和δ18O均分布在当地大气降水线(δD=8.87δ18O+17.59(R2=0.97))附近,表明滴水的δD和δ18O体现了当地大气降水δD和δ18O的平均水平;沉积物δ18O的变化范围小于相对应的滴水δ18O变化范围,更小于洞外大气降水,但3者都呈现出夏秋季偏轻、冬春季偏重的季节性变化趋势;与逐月大气降水量对比发现,沉积物δ18O受月"降雨量效应"影响较少,沉积物δ18O主要受冬夏季降水水汽源地季节性差异的影响.总体而言,玉华洞沉积物δ18O值存在较明显的季节特征,其波动较好的继承了当地大气降水信息,玉华洞石笋δ18O可以用来重建季节性高分辨率的古气候记录.     

北疆大气降水水汽源识别及其对地下水补给的指示意义

 大气降水是水循环的输入项,其同位素特征是示踪水汽来源及运动路径的有效工具。利用北疆4个大气降水观测站的同位素数据,结合HYSPLIT模式,重点分析了北疆大气降水同位素特征。区域大气降水线方程δD=7.3δ¹⁸O+3.5,反映了新疆独特的干旱气候环境。受不同降水水汽来源影响,天山及阿勒泰2个地区降水同位素特征表现不同。天山地区受西风带水汽季节性漂移的影响,氘盈余夏季低冬季高,成“V”型;阿勒泰地区常年受北冰洋水汽影响,氘盈余年内变幅不明显。尽管δ¹⁸O均表现为夏季富集、冬季贫化,但多年均值差异明显,该差异也使得利用同位素确定地下水补给来源成为可能。准东盆地东天山附近地下水主要受到来自东天山的大气降水补给,而北侧自流区地下水同位素相对贫化,与阿勒泰站大气降水同位素及氘盈余特征相似,结合地形、水文地质条件等特征,认为该区主要受克拉美丽山大气降水补给。     

东江下游大气降水氢氧同位素特征及水汽来源

大气降水是水循环系统的主要输入源,其氢、氧稳定同位素组成(δD、δ~(18)O)受区域气象、地理等因素变化影响较大,可以对环境变化做出快速、及时的响应,是研究全球和局地水循环特征的重要技术手段。东江流域地处我国珠江三角洲,季风环流通过影响水汽输送场的分布控制降水的时空分配。为研究区域降水成因及机理,本文采集并测定东江流域下游地区2017年逐日降水样品中δD、δ~(18)O,以月为研究时间尺度,分析其与气温、降水量之间的关系;利用HYSPLIT后向轨迹模式追踪降水气团的传输路径,进一步探讨区域降水的水汽来源及输送状况。结果表明,研究期间降水样品中δD的变化范围为-105.10‰～+9.98‰,雨量加权平均值为-57.88‰;δ~(18)O的变化范围为-14.80‰～-0.55‰,雨量加权平均值为-8.61‰,局地大气降水线为δD=8.60δ~(18)O+16.15(R~2=0.99)。月尺度下δ~(18)O最高值出现在1月份,为-3.47‰,最低值出现在8月份,为-10.17‰。δ~(18)O与气温、降水量均呈显著负相关关系,表现"反温度效应"和"降水量效应"。太平洋水汽带来的降水δ~(18)O、δD偏高,印度洋水汽带来的降水δ~(18)O、δD偏低,而南海降水气团中δ~(18)O、δD则随季节的不同而改变,表现为夏、秋两季明显较春季贫化,存在明显"降水同位素环流效应"。     

Indian monsoon influences altitude effect of δ~(18)O in precipitation/river water on the Tibetan Plateau

The δ^18O variation in precipitation acquired from 28 stations within the network of Tibetan Observation and Research Platform （TORP） is studied, with the focus on the altitude effect of δ^18O in river water during monsoon precipitation in an effort to understand the monsoon influence on isotopic composition in annual river water. It is found that δ^18O in precipitation on the Plateau is influenced by different moisture sources, with significant Indian monsoon influence on δ^18O composition in plateau precipitation and river water. The δ^18O of water bodies in the monsoon domain is generally more depleted than that in the westerly domain, suggesting gradual rainout of southwesterly borne marine moisture in the course of long-distance transportation and lifting over the Himalayas. The lapse rate of δ^18O in river water with altitude is the largest during monsoon precipitation, due to the increased temperature vertical gradient over the southern Plateau region controlled by monsoon circulation. The combination of δ^18O in river water in monsoon （wet） and non-monsoon （dry） seasons shows a larger lapse rate than that in non-monsoon （dry） season alone. As the altitude effect of δ^18O in precipitation and river water on the Tibetan Plateau results from the combined effect of monsoon moisture supply and westerly moisture supply, the δ^18O composition and its altitude effect on the Plateau during monsoon seasons should be considered in the reconstruction of paleoelevation of the Tibetan Plateau.     

胶州湾北岸不同水体水化学及氢氧同位素特征研究

为研究胶州湾北岸不同水体的水化学及氢氧同位素特征,通过样品测试及特征分析,揭示研究区地下水和地表水的水化学特征、补给来源和相互转化关系。研究结果表明：研究区基岩裂隙水水化学类型以Cl－Ca和Cl－Na.Ca型为主,TDS变化范围为582～1708 mg/l,整体以淡水为主,部分点位受海水入侵影响,呈微咸水特征;第四系孔隙水以Cl－Na和Cl.SO4－Na型为主,整体为咸水且化学组分较稳定;河水和胶州湾海水主要为Cl－Na型,河水水化学组分变化程度较大,受大气降水影响呈微咸水—咸水特征。水样点在Piper三线图上分为裂隙水分布区、孔隙水分布区和孔隙水与地表水混合区三个区域,说明研究区地表水和孔隙水具有密切水力联系,相互转化关系明显。祥茂河河水的主要来源为大气降水;洪江河、墨水河河水为大气降水与海水的混合水,且墨水河受海水混合影响程度大于洪江河;胶州湾海水为河水和标准海水的混合水。地下水主要接受大气降水的补给,不同水体受到不同程度的蒸发作用影响,孔隙水受蒸发作用影响较裂隙水强烈,且裂隙水和孔隙水存在密切的水力联系,孔隙水接受裂隙水的补给。     

华北型煤田奥灰水水化学和同位素特征研究——以兖州煤田为例

为了更好地理解研究区的水循环,并为突水水源判别打下基础,很有必要研究奥陶系地下水水化学和同位素特征。奥陶系灰岩水(简称奥灰水)主要的水化学类型为Ca-MgSO4,主要阳离子为SO2-4和Ca2+。Ca2+和SO2-4与TDS都有很好的线性相关性,R2值分别为0.978和0.996,而且随TDS的增加,Ca2+和SO2-4浓度增长速度也是最快的。奥灰水中方解石和白云石处于过饱和状态,但是石膏和方解石未饱和。Cl-和TDS的分布与地下水流场有较好的一致性。研究区代表性的雨水线为:δD=7.80δ18O+6.28,分析结果认为奥灰水不是当地降水的补给。     

Westerly moisture transport to the middle of Himalayas revealed from the high deuterium excess

Previous studies found extremely high d-excess in both ice core and glacial melt water in Dasuopu glacier, Xixiabangma, middle of Himalayas. These values are much higher than the global average and those measured in southwest monsoon precipitation. The d-excess variation in over one year at Nyalam station will clarify this phenomenon. Studies show that the high d-excess is related to the seasonal variation of moisture transport to this region. The d-excess values are low during the southwest monsoon active periods, when moisture originated from the humid ocean surface. The d-excess values are higher in non-monsoon months, when moisture is derived from westerly transport. Winter and spring precipitation accounts for a substantial portion of the annual precipitation, resulting in higher d-excess in the yearly precipitation in the middle of Himalayas than other parts of the southern Tibetan Plateau. This finding reveals that the precipitation in the middle of Himalayas is not purely from southwest monsoon, but a large portion from the westerly transport, which is very important for ice core study in this area.     

Origin of summer monsoon rainfall identified by δ18O in precipitation

A negative correlation between δ^18O in monsoon precipitation and f, the ratio of precipitable water in monsoon region to that in water source area, is hypothesized. Using the Rayleigh model, a new method for identifying origin of summer monsoon rainfall is developed based on the hypothesis. In order to validate the method, the isotopic data at New Delhi, a typical station in the southwest monsoon region, and Hong Kong, a typical station in the southeast monsoon region, were collected and analyzed for case studies. The case studies indicate that the water source areas of the monsoon rairdall at the two stations identified by the method are accordant with the general atmosphere circulation patterns. The method developed in this paper is significantly important for tracing the origin of summer monsoon precipitation.     

Modern stalagmite oxygen isotopic composition and its implications of climatic change from a high-elevation cave in the eastern Qinghai-Tibet Plateau over the past 50 years

An oxygen isotope record of a stalagmite from Huanglong Cave in the eastern Qinghai-Tibet Plateau dated with 230Th and 210Pb methods provides variations of the Asian monsoon with an average resolu-tion of 1 year over the past 50 years. This study shows that the δ18O of dripwater in the cave represents the annual mean δ18O of local meteoric precipitation and the stalagmites were deposited in isotopic equilibrium. A comparison of the stalagmite δ18O record with instrumentally meteorological data indi-cates that shifts of the δ18O are largely controlled by the amount effect of meteoric precipitation con-veyed through the southwest monsoon(the Indian monsoon) and less affected by temperature. Therefore,the variations of δ18O record reflect the changes in monsoon precipitation on inter-annual time scales under the influence of the southwest monsoon. Like many other stalagmite δ18O records in the Asian monsoon regions,the δ18O record of the stalagmite from Huanglong Cave also reveals a gradually enriched trend during the past 50 years,i.e. relatively enriched in 18O. This trend may indicate the decline of the Asian monsoon intensity which is consistent with the decrease of monsoon indices. The weakening of the modern Asian monsoon well matched with the temperature changes in strato-sphere,which may illustrate that the weakening of the monsoon mainly results from the lowering of solar radiation.     

The δ18O variation of a stalagmite from Qixing Cave, Guizhou Province and indicated climate change during the Holocene

A stalagmite from Qixing Cave, Guizhou Province was dated with the TIMS U-series method and its oxygen isotope composition was analyzed. On the basis of the ages and the variations of the δ¹⁸O of the stalagmite, the climate change of the last 7.7 ka has been reconstructed in this area: 7.7–5.8 ka, summer monsoon maximum period; 5.8–3.8 ka summer monsoon weakening period; 3.8–0.15 ka, weakened summer monsoon and high amplitude climate fluctuations period. We put forward that the increasing trend of δ¹⁸O of the stalagmite reflected not only the weakening of the summer monsoon, which was caused by the decreasing of solar radiation in the Northern Hemisphere, but also the possibly decreasing contribution of the southwest monsoon to the rainfall of this area. These results are consistent with the output of the numerical climate-model modeling. The high amplitude fluctuation of the δ¹⁸O may imply the quick shift of the contributions of different moisture sources to the precipitation in this area.     

A high-resolution stalagmite O-C isotope record from Nanjing and its rapid response to climatic events

Here we discussed rapid response of the cave temperature and vegetation to the four Dansgaard-Oeschger cold and warm cycles during 50-40 kaBP based on results of oxygen and carbon stable isotopic compositions from a stalagmite in Tangshan, Nanjing. It is found that the amount of C₃ vegetation relative to C₄-type declines during the D-O warm events, indicating the decrease of the effective meteoric precipitation. Compared with O-isotope records of the Greenland ice core, the stalagmite record displays a very similar pattern to Greenland ice core record over the decade-century time scale, suggesting that the changes of the East Asian monsoon climate are in accordance with the high-latitude polar climate in the short-term time scale. The age of the ice-rafted H5 event in the stalagmite record, however, preceded that of Greenland ice cores by 2 ka. This out of phase between the remote areas cannot be yet proven because the two time scales were determined from different dating methods.     

A method for estimating the contribution of evaporative vapor from Nam Co to local atmospheric vapor based on stable isotopes of water bodies

During the summer monsoon season,the moisture of precipitation events in southern and central regions of the Tibetan Plateau is mainly moisture from the Indian Ocean transported by the Indian monsoon and terrestrial vapor derived from the surface of the Tibetan Plateau.However,the respective contributions of these two types of moisture are not clear.From June to September,the excess deuterium values of precipitation and river water in the Nam Co basin are higher than those for the southern Tibetan Plateau.This reflects the mixing of evaporation from Nam Co and local atmospheric vapor.On the basis of theory for estimating the contribution of evaporative vapor from surface water bodies to atmospheric vapor and relative stable isotopes in water bodies (precipitation,river water,atmospheric moisture and lake water),this study preliminarily estimates that the average contribution of evaporation from the Lake Nam Co to local atmospheric vapor has varied from 28.4% to 31.1% during the summer monsoon season in recent years.