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Nancy England April L. James Krystopher J. Chutko Richard S. Pyrce Huaxia Yao 《水文研究》2019,33(6):905-919
Stable water isotope surveys have increasingly been integrated into river basins studies, but fewer have used them to evaluate impact of hydropower regulation. This study applies hydrologic and water isotope survey approaches to a Canadian Shield river basin with both regulated and natural flows. Historical streamflow records were used to evaluate the influence of three hydroelectric reservoirs and unregulated portions of the basin on downstream flows and changes in water level management implemented after an extreme flood year (1979). In 2013, water isotope surveys of surface and source waters (e.g., rainfall, groundwater, snowmelt) were conducted to examine spatial and temporal variation in contributions to river flow. Seasonal changes in relative groundwater contribution were assessed using a water‐isotope mass balance approach. Within the basin, two regulated reservoirs exhibited inverted hydrographs with augmented winter flows, whereas a third exhibited a hydrograph dominated by spring snowmelt. In 2013, spatial variation in rain‐on‐snow and air temperatures resulted in a critical lag in snowmelt initiation in the southern and northern portions of the basin resulting in a dispersed, double peak spring hydrograph, contrasting with 1979 when a combination of rain‐on‐snow and coincident snowmelt led to the highest flood on record. Although eastern basin reservoirs become seasonally enriched in δ18O and δ2H values, unregulated western basin flows remain less variable due to groundwater driven baseflow with increasing influence downstream. Combined analysis of historical streamflow (e.g., flood of 1979, drought of 2010) and the 2013 water isotope surveys illustrate extreme meteorological conditions that current management activities are unable to prevent. In this study, the influence of evaporative fractionation on large surface water reservoirs provides important evidence of streamflow partitioning, illustrating the value of stable water isotope tracers for study of larger catchments. 相似文献
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In‐situ analysis of trace elements and Sr–Pb isotopes of K‐feldspars from Tongshankou Cu–Mo deposit,SE Hubei Province,China: Insights into early potassic alteration of the porphyry mineralization system 
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下载免费PDF全文 In the Tongshankou porphyry deposit (SE Hubei Province, South China), three types of K‐feldspars are recognized: (I) the phenocryst type in the porphyry that crystalized during the magmatic stage, (II) the megacryst type and (III) the vein type in the altered porphyry and orebody that was produced by hydrothermal fluids. A detailed in‐situ analysis of trace elements and Sr–Pb isotopes was carried out on K‐feldspars in an attempt to unravel their formation processes and to trace the element sources during potassic alteration. The Type III K‐feldspars show lower Sr contents and Sr‐isotope ratios but higher Pb contents and Pb‐isotope ratios than the Type I and II K‐feldspars, possibly reflecting a contribution from the country carbonate rocks with less radiogenic Sr but more radiogenic Pb sources, and indicate that the ore‐forming fluids and materials may have been partially derived from external sources such as the host sedimentary rocks during the early potassic alteration stage. 相似文献
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兰州盆地位于青藏高原东北部,祁连山以东,黄土高原以西,古近纪出露地层为细柳沟组、野狐城组和咸水河组下段。作为青藏高原寒区、东部季风区及西北干旱区的交汇地带,兰州地区新生代环境研究受到越来越多的关注,因此有必要对其沉积环境进行研究。本文通过对兰州盆地黄羊头地区古近系进行分段采样,并对泥岩样品的主量元素、微量元素及X射线衍射进行测定,运用硼法、B/Ga值及Sr/Ba值等方法定量—半定量分析兰州盆地古近系沉积时的古盐度特征,同时结合风化指数CIA值的变化特征,综合分析古近系的沉积环境。研究结果表明兰州盆地古近系细柳沟组、野狐城组及咸水河组下段Adams法古盐度值为9.5‰～14.0‰,平均值为11.8‰;Couch法古盐度值为8.2‰～12.8‰,平均值为10.8‰,为内陆半咸水—淡水湖泊。Adams法古盐度值与B/Ga值具有良好的正相关关系,而Adams古盐度值与Sr/Ba值相关性不明显,主要由于地层中生物对Sr的富集作用,导致Sr/Ba值偏大,表明Sr/Ba值不适用于生物富集地层的古盐度恢复。环境研究认为细柳沟期,气候湿润,以冲积扇沉积为主,水体较浅,盐度值较大;到野狐城中期水体加深,变为湖相沉积,气候温暖湿润,盐度值降低,同时存在明显的干冷气候间隙,该间隙期湖盆蒸发量大于补给量,盐度值升高;从野狐城晚期开始湖盆逐渐萎缩,以滨湖相沉积为主,到韩家井期变为河流相沉积,至甘家滩期再次转为湖相沉积,盐度值先升高后降低,但整体风化程度明显降低,表明从野狐城组晚期开始气候逐渐变冷变干。 相似文献
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