东南沿海流域河水氢氧同位素时空变化特征

Spatiotemporal Variation Characteristics of Hydrogen and Oxygen Isotopes in Runoff of Southeast Coastal Watersheds

为深入了解东南沿海流域水文循环过程,以厦门市东西溪流域为例,采集东西溪干流上中下游枯、平、丰水期降雨、径流样品,探求河水中氢氧同位素(δD、δ^(18)O)组成时空变化特征。结果表明,受温度、降雨量的影响,河水中δD、δ^(18)O不同水期变化明显,枯平水期富集、丰水期贫化,δD、δ^(18)O降雨量效应大于温度效应;在不同水期,河水中δD、δ^(18)O均表现出从上游至下游富集趋势;东西溪河水δD、δ^(18)O值均落在流域大气降雨线附近,大气降雨为东西溪径流最重要的补给来源,其中丰水期河水线斜率最大,分馏程度最高。

In order to deeply understand the hydrological cycle process of the southeast coastal basin,taking Dongxi River in Xiamen City for an example,precipitation and runoff samples were collected from the upper,middle and lower reaches of the Dongxi River in dry,flat and wet periods to analyze the spatiotemporal variation characteristics of hydrogen and oxygen isotopes(δD,δ^(18)O).The results show that the δD andδ^(18)O in runoff vary significantly in different water periods.Isotope enrichment in normal water period and depletion in wet water period are closely tied to temperature and rainfall.δD and δ^(18)O are more affected by rainfall than by temperature.The δD andδ^(18)O in runoff showed a trend of enrichment from upstream to downstream in different water periods.The δD and δ^(18)O values of the runoff all fall near the atmospheric rainfall line,and the rainfall is the most important replenishment source of the runoff from Dongxi River.The slope of hydrogen and oxygen isotope relationship line is the highest and the degree of fractionation is the highest in wet seasons.