Álvarez-Vázquez Miguel Ángel, Prego Ricardo, Caetano Miguel, De Uña-Álvarez Elena, Doval Maryló, Calvo Susana, Vale Carlos
Instituto de Investigaciones Marinas (CSIC), 36208, Vigo, Spain; Área de Geografía Física, Grupo GEAAT, Campus de Ourense (UVigo), 32004, Ourense, Spain.
Instituto de Investigaciones Marinas (CSIC), 36208, Vigo, Spain.
Chemosphere. 2017 Jul;178:173-186. doi: 10.1016/j.chemosphere.2017.03.053. Epub 2017 Mar 15.
Trace element contributions from small rivers to estuaries is an issue barely addressed in the literature. In this work, freshwater flowing into the Ria of Cedeira (NW Iberian Peninsula) was studied during a hydrological year through the input from three rivers, one considered uncontaminated (the Das-Mestas River), a second affected by urban treated wastewater discharges (the Condomiñas River), and the third containing a water reservoir for urban supply (the Forcadas River). With the objective of assessing the possible influence of human pressure, the annual yields for selected trace elements (Al, Fe, As, Cd, Co, Cr, Cu, Mn, Mo, Ni and Pb) were estimated and compared by normalizing by basin surface. Both dissolved and particulate transported elements were considered. After the data treatment and analysis it can be highlighted that: (i) the Das Mestas River is suitable to be included between the short European pristine baseline of small rivers, at least regarding the transported trace elements; (ii) natural enrichments were identified associated to the lithology of the basin in the Das-Mestas River (i.e. As) and in the Condomiñas River (i.e. Co, Cr and Ni); this fact highlights the importance of considering the local background for a proper assessment; (iii) the impoundment in the Forcadas River is related with a general decrease, even depletion, of the particulate and dissolved transported trace elements, except Mn; (iv) the discharge of sewage to the Condomiñas River is increasing the inputs to the ria of some trace elements in the particulate phase (i.e. Al, Cu and Pb). Both observed human-induced changes can be regarded as typical disturbances of trace element contributions from small rivers to estuaries.
小河流对河口的微量元素贡献是一个在文献中几乎未被涉及的问题。在这项研究中，在一个水文年期间，对流入塞德拉湾（伊比利亚半岛西北部）的淡水进行了研究，该淡水来自三条河流，一条被认为未受污染（达斯 - 梅斯塔斯河），第二条受到城市处理后废水排放的影响（孔多米尼亚斯河），第三条包含一个用于城市供水的水库（福尔卡达斯河）。为了评估人类活动压力的可能影响，通过对流域面积进行归一化，估算并比较了选定微量元素（铝、铁、砷、镉、钴、铬、铜、锰、钼、镍和铅）的年产量。同时考虑了溶解态和颗粒态传输的元素。经过数据处理和分析，可以突出以下几点：（i）达斯 - 梅斯塔斯河至少就所传输的微量元素而言，适合被纳入欧洲小河流的短原始基线范围内；（ii）在达斯 - 梅斯塔斯河（如砷）和孔多米尼亚斯河（如钴、铬和镍）中，发现了与流域岩性相关的自然富集现象；这一事实凸显了考虑当地背景以进行恰当评估的重要性；（iii）福尔卡达斯河的蓄水与颗粒态和溶解态传输的微量元素（锰除外）普遍减少甚至枯竭有关；（iv）向孔多米尼亚斯河排放污水正在增加颗粒相中某些微量元素（如铝、铜和铅）向河口湾的输入量。所观察到的这两种人为引起的变化都可被视为小河流对河口微量元素贡献的典型干扰。
