Deng Wen Ping, Zhang Jie, Zhang Zhi Jian, Hu Shao Chang, Guo Jin Rong, Liu Yuan Qiu, Kong Fan Qian, Zhang Yi
College of Forestry, Jiangxi Agricultural University, Nanchang 330045, China.
Academy of Nur-sing, Jiujiang University, Jiujiang 332000, Jiangxi, China.
Ying Yong Sheng Tai Xue Bao. 2017 Jul 18;28(7):2171-2178. doi: 10.13287/j.1001-9332.201707.018.
The stable hydrogen and oxygen isotopes are environmental isotopes, which widely exist in various kinds of water. Their relative abundance variation in water can indicate the water circulation and mechanism of water use in plant. This research selected two major kinds of greening tree species, evergreen coniferous Platycladus orientalis and deciduous broad-leaved Quercus variabilis, in Beijing mountainous area, and the water movement process in soil-plant-atmosphere continuum was investigated by the variation characteristics analysis of stable hydrogen and oxygen isotope compositions in precipitation, soil water, groundwater, plant stem water and leaf water. The results showed that the meteoric water line equation of the study area was δD=7.17δO+1.45 (R=0.93), and the soil evaporation line equation was δD=3.85δO+1.45 (R=0.76). A certain degree of evaporation fractionation existed in the processes of rainfall infiltration into soil water. In different seasons, the δD and δO values of precipitation, soil water and spring water had different variation regularity. In rainy season, the mean δD and δO values were in order of precipitation> spring water>soil water, with the precipitation and soil water supplied spring water together; in dry season, the order was precipitation > soil water > spring water, and the precipitation and spring water both contributed to soil water. The δD and δO fitting line equations of stem water of P. orienta-lis and Q. variabilis were respectively δD=5.03δO-30.78 and δD=3.0δO-48.92. The uptake water of Q. variabilis was more enriched than that of P. orientalis, and the depth of Q. variabilis water uptake in soil profile was shallower than P. orientalis. The leaf water isotopic variation of Q. varia-bilis was more sensitive to atmospheric environment, with the kinetic isotopic fractionation of Q. variabilis being more enriched than that of P. orientalis, but they had the same response to variation of environmental condition.
稳定氢氧同位素是环境同位素，广泛存在于各类水体中。它们在水中的相对丰度变化能够指示水循环以及植物的水分利用机制。本研究选取了北京山区两种主要的绿化树种，常绿针叶树侧柏和落叶阔叶树栓皮栎，通过对降水、土壤水、地下水、植物茎干水和叶片水中稳定氢氧同位素组成的变化特征分析，研究了土壤 - 植物 - 大气连续体中的水分运动过程。结果表明，研究区大气降水线方程为δD = 7.17δO + 1.45（R = 0.93），土壤蒸发线方程为δD = 3.85δO + 1.45（R = 0.76）。降雨入渗到土壤水的过程中存在一定程度的蒸发分馏作用。在不同季节，降水、土壤水和泉水的δD和δO值具有不同的变化规律。雨季时，δD和δO的平均值顺序为降水>泉水>土壤水，降水和土壤水共同补给泉水；旱季时，顺序为降水>土壤水>泉水，降水和泉水均补给土壤水。侧柏和栓皮栎茎干水的δD和δO拟合线方程分别为δD = 5.03δO - 30.78和δD = 3.0δO - 48.92。栓皮栎吸收的水分比侧柏更富集，栓皮栎在土壤剖面中的吸水深度比侧柏浅。栓皮栎叶片水同位素变化对大气环境更敏感，栓皮栎的动力学同位素分馏比侧柏更富集，但它们对环境条件变化的响应相同。
