论文利用北京西山鹫峰地区2011年7月—2012年7月观测站点内大气降水δD和δ18O数据,研究了北京西山山前丘陵区降水稳定同位素的变化特征。结果表明：研究区的大气降雨δD和δ18O的平均值要低于中国和全球降水同位素的平均值,并与北京地区的降水同位素组成平均值之间显示出较大的差异,且同一个月份内降水的同位素特征也具有较大的变化范围。由于季风气候以及局地水汽循环的共同影响,使得夏季降水中的δD和δ18O值较小,并且在4—7月随着月降水量的增加和温度的升高,在温度效应和降雨量效应的交互作用中,降雨量效应此时起主导作用,月均δD和δ18O值呈现减小的趋势,而在7—9月,温度效应呈现出主导作用,δD和 δ18O值呈现增加的趋势,而冬季来自偏北风的大陆性气团形成的降水δD和δ18O值较大。同时局地水汽循环过程中降水的二次蒸发,也导致在典型长历时场降水过程中δD和δ18O值呈现出分段波动式下降的特征。研究区大气降水线方程为 δD = 7.17 δ18O + 1.46,斜率和截距小于全球和中国大气降水线方程,而与北京地区大气降水线方程的对比发现,斜率差异较小而截距差异明显,说明海洋水汽不是研究区唯一的水汽来源,同时受到大陆性气团以及局地较强的水汽循环和北京地区近年的干旱化过程的影响。而氘盈余的年内变化的无规律则间接反映了研究区水汽来源的复杂性。
Stable isotopes of δD and δ18O in precipitation are investigated in western mountains of Beijing from July 2011 to July 2012. The results show that the mean values of δD and δ18O in precipitation in the study area were lower than those in global and in China, and had great difference to those in Beijing, and the isotope values of precipitation within the same month showed great variations. Because of the mutual influence of monsoon climate and atmospheric water vapor cycle, the stable isotopes of δD and δ18O in summer precipitation were less. The isotopic values decreased with the increase of monthly precipitation and temperature from April to July since the rainfall played the leading role in the interaction process of temperature and rainfall. The isotopic values increased from July to September when the temperature took the leading role. There are more stable isotopes of δD and δ18O in winter precipitation since the precipitation was formed in the continental air masses from the northerly winds. The second evaporation after the rainfall in the process of atmospheric water vapor cycle also causes the piecewise fluctuated decline of δD and δ18O in a typical long duration of rain. The meteoric water line equation of the study areas was δD=7.17δ18O+1.46 (R2=0.934 2), and the slope and intercept were lower than those in the national and global atmospheric precipitation line equations. When compared to the meteoric water line equation of Beijing, the slope of the equation was similar and the intercept was obviously different, which indicated that the ocean water vapor was not the only source of water vapor in the study area, the values of isotopes in the precipitation in this area were also influenced by the continental air masses, local strong water vapor cycle and the drying process in recent years. The irregularity of deuterium excess indirectly reflected the complexity of water source in the study area.
[1] ARAGUÁS-ARAGUÁS L, FROEHLICH K, ROZANSKI K. Stable isotope composition of precipitation over southeast Asia [J]. Journal of Geophysical Research, 1998, 1032(D22): 28721-28742．
[2] 柳鉴容, 宋献方, 袁国富, 等. 西北地区大气降水 δ 18 O 的特征及水汽来源 [J]. 地理学报, 2008, 63(1): 12-22.
[3] DANSGAARD W. The abundance of δ 18 O in atmospheric water and water vapour [J]. Tellus, 1953, 5(4): 461-469.
[4] DANSGAARD W. Stable isotopes in precipitation [J]. Tellus, 1964, 16(4): 436-468.
[5] CRAIG H. Isotopic variations in meteoric waters [J]. Science, 1961, 133(3465): 1702-1703.
[6] YURTSEVER Y. Worldwide Survey of Stable Isotopes in Precipitation [M]. Vienna: International Atomic Energy Agency, 1975: 53.
[7] INGRAHAM N L, TAYLOR B E. Light stable isotope systematics of large-scale hydrologic regimes in California and Nevada [J]. Water Resources Research, 1991, 27(1): 77-90.
[8] BENJAMIN L, KNOBEL L L, HALL L F, et al. Development of a local meteoric water line for southeastern Idaho, western Wyoming, and south-central Montana [R]. Scientific Investigations Report 2004-5126. U.S. Geological Society, Idaho Falls, Idaho, 2004.
[9] ETTAYI N, BOUCHAOU L, MICHELOT J L, et al. Geochemical and isotopic (oxygen, hydrogen, carbon, strontium) constraints for the origin, salinity, and residence time of groundwater from a carbonate aquifer in the western Anti-Atlas Mountains, Morocco [J]. Journal of Hydrology, 2012, 438/439: 97-111.
[10] 章申, 于维新, 张青莲, 等. 我国西藏南部珠穆朗玛峰地区冰川中氘和重氧的分布 [J]. 中国科学A辑, 1973, 3(4): 430-433.
[11] 宋献方, 柳鉴容, 孙晓敏, 等. 基于 CERN 的中国大气降水同位素观测网络 [J]. 地球科学进展, 2007, 22(7): 738-747.
[12] 姚檀栋, 丁良福, 蒲建辰, 等. 青藏高原唐古拉山地区降雪中δ 18 O特征有其与水汽来源的关系 [J]. 科学通报, 1991, 36(20): 1570-1573.
[13] 卫克勤, 林瑞芬, 王志祥. 北京地区降水中的氘, 氧-18, 氚含量 [J]. 中国科学B辑, 1982(8): 754-757.
[14] 康世昌, 秦大河, 姚檀栋, 等. 希夏邦马峰达索普冰川高海拔区夏季风期间大气降水的δ 18 O特征 [J]. 山地学报, 2000, 18(1): 1-6.
[15] 田立德, 姚檀栋, NUMAGUTI A, 等. 青藏高原南部季风降水中稳定同位素波动与水汽输送过程 [J]. 中国科学D辑, 2001, 31(S1): 215-220.
[16] 庞洪喜, 何元庆, 张忠林. 季风降水中δ 18 O与高空风速关系 [J]. 科学通报, 2004, 49(9): 905-908.
[17] 章新平, 姚檀栋. 我国降水中的δ 18 O的分布特点 [J]. 地理学报, 1998, 53(4): 356-363.
[18] 李青春, 张朝林, 苗世光, 等. 北京地区降水量分布特征及下垫面性质对降水量分布的影响研究 [J]. 中国沙漠, 2005, 25(S1): 60-65.
[19] 蔡明刚, 黄奕普, 陈敏, 等. 厦门大气降水的氢氧同位素研究 [J]. 台湾海峡, 2000,19(4): 446-453.
[20] 郑淑蕙, 侯发高, 倪葆龄. 我国大气降水的氢氧稳定同位素研究 [J]. 科学通报, 1983, 28(13): 801-806.
[21] 翟远征, 王金生, 滕彦国, 等. 北京市不同水体中 δD 和δ 18 O 组成的变化及其区域水循环指示意义 [J]. 资源科学, 2011, 33(1): 92-97.
[22] 邓文平, 余新晓, 贾国栋. 华北地区大气降水稳定同位素特征与水汽来源 [J]. 矿物岩石地球化学通报, 2012, 31(5): 489-494.
[23] 涂林玲, 王华, 冯玉梅. 桂林地区大气降水的 D 和 18 O 同位素的研究 [J]. 中国岩溶, 2004, 23(4): 304-309.
[24] 刘鑫, 宋献方, 夏军, 等. 黄土高原岔巴沟流域降水氢氧同位素特征及水汽来源初探 [J]. 资源科学, 2007, 29(3): 59-66.
[25] CLARK I D, FRITZ P. Environmental Isotopes in Hydrogeology [M]. Bocaaton, US: Lewis Publisherers, 1997.
[26] 侯典炯, 秦翔, 吴锦奎, 等. 乌鲁木齐大气降水稳定同位素与水汽来源关系研究 [J]. 干旱区资源与环境, 2011, 25(10): 136-142.
[27] 卫克勤, 林瑞芬. 论季风气候对我国雨水同位素组成的影响 [J]. 地球化学, 1944, 23(1): 33-41.
