The geographic location of Andalusia, bordered by the Atlantic Ocean and the Mediterranean Sea, and its great topographic and climate diversity enable the analysis of different factors that condition the isotopic composition of precipitation and groundwater. A total of 42 karst springs representative of the main carbonate aquifers were selected in order to sample the base flow waters during the summer of 2020. Isotopic analyses revealed that groundwater δ¹⁸O was between −5.04 and −9.85‰ while that of δ²H was between −26.39 and −62.69‰. Weighted mean isotopic data for precipitation, from six IAEA stations in the study area, was between −4.67 and −9.06‰ for δ¹⁸O, and between −24.93 and −58.99 ‰ for δ²H. The results showed that diffuse flow groundwaters are lighter and have higher d-excess than meteoric waters, which may be due to preferential recharge during winter months and the sub-cloud evaporation effect. The spatial variation of d-excess, with average values around 14 ‰ in the Atlantic watershed and 17 ‰ in the Mediterranean watershed, has showed for the first time the effect of the Atlantic-Mediterranean divide on the isotopic composition of spring waters. Furthermore, a progressive decrease in δ¹⁸O towards the east of the study area seems to be related to the effects of continentality and altitude. This also allowed us to conclude that, in the areas with highest rainfall, springs drain waters with a relatively higher content of heavy isotopes than expected from the regional altitudinal gradient, while springs in drier areas discharge lighter waters. These differences can be attributed to a longer recharge period in the former, which extends in the warmer months or autumn and spring.

中文翻译：

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地势和气候对大西洋-地中海岩溶泉水同位素组成的影响（西班牙南部安达卢西亚）

安达卢西亚与大西洋和地中海接壤的地理位置及其巨大的地形和气候多样性使得分析影响降水和地下水同位素组成的不同因素成为可能。2020年夏季，共选取代表主要碳酸盐含水层的岩溶泉42个，对基流水进行采样。同位素分析显示，地下水δ ¹⁸ O介于-5.04和-9.85‰之间，δ ² H介于 -26.39 和 -62.69‰ 之间。来自研究区六个国际原子能机构站的降水加权平均同位素数据，δ ^{18 O 介于 -4.67 和 -9.06‰ 之间，δ 2}介于 -24.93 和 -58.99 ‰ 之间H. 结果表明，扩散流地下水比大气水更轻，具有更高的 d-过量，这可能是由于冬季优先补给和云下蒸发效应。d-excess的空间变化，在大西洋流域的平均值约为14 ‰，在地中海的流域为17 ‰，首次显示了大西洋-地中海分水岭对泉水同位素组成的影响。此外，δ ^{18逐渐减少}研究区域以东的 O 似乎与大陆性和海拔的影响有关。这也使我们得出结论，在降雨量最大的地区，泉水排放的重同位素含量相对高于区域海拔梯度的预期，而较干燥地区的泉水排放较轻的水。这些差异可归因于前者的补给期较长，在较温暖的月份或秋季和春季会延长。