榆神府矿区土壤-植被-大气系统中水分的稳定性同位素特征

Isotopic characteristics of water within the soil-vegetation-atmosphere system in the Yushenfu mining area

针对榆神府矿区植物水分来源研究方面存在的不足,以影响矿区植被建设中最关键的制约性因素水分为中心,利用稳定性同位素分馏原理,分析了矿区土壤-植被-大气系统不同载体中水分的稳定性同位素特征,揭示了矿区典型植物的水分来源,为矿区植被的自然恢复和永续发展提供科学的水分来源依据。研究认为,榆神府矿区夏季降水δD(氘)、δ18Ο(重氧)与降水量成明显的负相关关系,表明该区降水氢、氧稳定性同位素具有较强的雨量效应特征。与全球大气降水线方程相比,矿区降水线方程(δD=7.0δ18Ο-0.72)斜率和截距都偏小,说明全球大气降水线方程不能很好地反映矿区降水的氢氧同位素特征。矿区典型植物木质部水分δD值(-72.49‰～-78.72‰)与土壤中水分(-68.15‰～-78.00‰)、地下水δD(-64.18‰～-67.14‰)相接近,与降水(10.78‰～-94.30‰)、水库水(-48.945‰)和湖水δD(-2.65‰)相差很大,说明该区植物水分的主要来源是土壤水和地下水,而基本没有直接利用湖水、水库水以及夏季降水。低δD值、雨量大时的降水是榆神府矿区地下水的主要补充来源,降雨量小时δD值高,但微小的补充不足以影响地下水的δD值。

Analyzed the isotopic characteristics of water within the soil-vegetation-atmosphere system in the Yushenfu mining area,and determined the source of water found in typical local plants using stable isotope fractionation techniques and principles.The purpose of the study is to determine if groundwater is used by plants and to provide scientific foundations about water sources essential for vegetation recovery and sustainable development.The results show that there is a significant negative correlation between δD（deuterium）,δ18Ο（oxygen-18） and precipitation,indicating that stable isotopes of hydrogen and oxygen are greatly affected by rainfall in the Yushenfu mining area.Compared to the Global Meteoric Water Line（GMWL）,the slope and intercept values of the summer Local Meteoric Water Line（LMWL,δD = 7.0δ18Ο-0.72） are smaller,which indicates that the hydrogen and oxygen isotopic characteristics of precipitation are not well represented by GMWL.The δD values in the xylems of typical plants（-72.49‰ ～-78.72‰） are close to those in soil water（-68.15‰ ～-78.00‰） and groundwater（-64.18‰ ～-67.14‰） and are significantly different from those in precipitation（10.78‰ ～-94.30‰）,reservoirs（-48.945‰） and lakes（-2.65‰）,indicating that the main water sources of plants could be soil and groundwater.High rainfall with lower δD values is a major source of groundwater,while low rainfall with higher δD values does not affect the δD values of groundwater.