Universidad de Málaga, Facultad de Ciencias, Grupo de Geodinámica Externa, Campus de Teatinos s/n, 29071 Málaga, Spain.
Universidad de Málaga, Facultad de Ciencias, Grupo de Geodinámica Externa, Campus de Teatinos s/n, 29071 Málaga, Spain.
Sci Total Environ. 2015 Feb 15;506-507:46-57. doi: 10.1016/j.scitotenv.2014.10.090. Epub 2014 Nov 15.
The integrated use of isotopes (δ(34)S-SO4, δ(18)O-SO4, δ(15)N-NO3, δ(18)O-NO3), taking into account existing hydrogeological knowledge of the study area (mainly hydrochemical), was applied in the Guadalhorce River Basin (southern Spain) to characterise SO4(2-) and NO3(-) sources, and to quantify natural background levels (NBLs) in groundwater bodies. According to Water Framework Directive 2000/60/EC and, more recently, Groundwater Directive 2006/118/EC, it is important to determine NBLs, as their correct assessment is the first, essential step to characterising groundwater bodies, establishing threshold values, assessing chemical status and identifying trends in pollutant concentrations. In many cases, NBLs are high for some parameters and types of groundwater, making it difficult to distinguish clearly between factors of natural or human origin. The main advantages of using stable isotopes in a complex area like the Guadalhorce River Basin that exhibits widely varying hydrogeological and hydrochemical conditions and longstanding anthropogenic influences (mainly agriculture, but also many others) is accurate determination of pollution sources and precise quantification of NBLs. Since chemical analyses only provides the concentration of pollutants in water and not the source, three isotopic sampling campaigns for sulphates (δ(34)S-SO4, δ(18)O-SO4) were carried out, in 2006, 2007 and 2012, and another one was conducted for nitrates (δ(15)N-NO3, δ(18)O-NO3), in 2009, in groundwater bodies in order to trace the origins of each pollutant. The present study identified different pollution sources of dissolved NO3(-) in groundwater using an isotopic composition and quantified the percentage of natural (lithology, chemical and biological processes) and anthropogenic (fertilisers, manure and sewage) SO4(2-) and matched a concentration associated with the percentage in order to determine the NBLs in the basin.
综合利用同位素（δ(34)S-SO4、δ(18)O-SO4、δ(15)N-NO3、δ(18)O-NO3），并结合研究区域现有的水文地质知识（主要是水化学），对西班牙南部 Guadalhorce 河流域的 SO4(2-)和 NO3(-)来源进行了特征描述，并量化了地下水的自然背景水平（NBL）。根据 2000/60/EC 号水框架指令和最近的 2006/118/EC 号地下水指令，确定 NBL 非常重要，因为正确评估 NBL 是对地下水体进行特征描述、建立阈值、评估化学状况和识别污染物浓度趋势的第一步，也是必不可少的一步。在许多情况下，对于某些参数和类型的地下水，NBL 较高，使得很难清楚地区分自然或人为因素。在像 Guadalhorce 河流域这样一个水文地质和水化学条件复杂、长期受到人为影响（主要是农业，但也有许多其他影响）的复杂地区，使用稳定同位素的主要优势是可以准确确定污染源，并精确量化 NBL。由于化学分析仅提供水中污染物的浓度，而不提供其来源，因此在 2006 年、2007 年和 2012 年进行了三次硫酸盐（δ(34)S-SO4、δ(18)O-SO4）的同位素采样活动，并在 2009 年进行了另一次硝酸盐（δ(15)N-NO3、δ(18)O-NO3）的同位素采样活动，以便追踪每种污染物的来源。本研究利用同位素组成确定了地下水中溶解态 NO3(-)的不同污染源，并量化了自然（岩性、化学和生物过程）和人为（肥料、粪便和污水）SO4(2-)的比例，并匹配了与该比例相关的浓度，以确定流域内的 NBL。
