Cavalcante Mariany Sousa, Marins Rozane Valente, Mounier Stéphane
Instituto de Ciências do Mar, Universidade Federal do Ceará, Avenida Abolição, Fortaleza, Ceará, 60165-081, Brazil.
Mediterranean Institute of Oceanography, Université de Toulon, Av. de L'Université, 83130, Toulon, France.
Environ Sci Pollut Res Int. 2024 May;31(23):34309-34323. doi: 10.1007/s11356-024-33521-5. Epub 2024 May 3.
Droughts are becoming more intense and frequent in the Brazilian semiarid because of El Niño and global climate changes. The Jaguaribe River estuary is a semiarid ecosystem that experiences a reduction in freshwater discharges due to droughts and river damming. The decrease in freshwater fluxes has increased metal availability through the water residence time increase in the Jaguaribe River estuary. Then, this study aimed to evaluate the dissolved organic matter quality and its interaction with metals in the Jaguaribe River estuary after a severe drought period. It was performed through carbon analyses, fluorescence spectroscopy, ultrafiltration technique, and determinations of metals by ICP-MS. Optical analysis showed that the dissolved organic carbon (DOC) was preponderantly composed of terrestrial-derived humic compounds, while the low ratio between the particulate organic carbon (POC) and chlorophyll-a indicated that POC was predominantly phytoplankton-derived. DOC and POC presented non-conservative removal during the estuarine mixing. DOM and dissolved elements were mostly distributed within the LMW fraction and presented a low percentage in the colloidal fraction. Li, Rb, Sr, Mo, and U showed conservative behavior, while Cu, Fe, Cr, and V had non-conservative behavior with a significant positive correlation with DOM, suggesting DOM as a relevant driver of metal availability at the Jaguaribe River estuary even during the rainy season.
由于厄尔尼诺现象和全球气候变化，巴西半干旱地区的干旱正变得愈发强烈和频繁。雅瓜里贝河河口是一个半干旱生态系统，由于干旱和河流筑坝，其淡水排放量减少。淡水通量的减少通过雅瓜里贝河河口水体停留时间的增加提高了金属的有效性。因此，本研究旨在评估在一段严重干旱期后雅瓜里贝河河口溶解有机物的质量及其与金属的相互作用。研究通过碳分析、荧光光谱法、超滤技术以及利用电感耦合等离子体质谱仪测定金属来进行。光学分析表明，溶解有机碳（DOC）主要由陆地来源的腐殖化合物组成，而颗粒有机碳（POC）与叶绿素-a之间的低比率表明POC主要来源于浮游植物。DOC和POC在河口混合过程中呈现非保守性去除。溶解性有机物（DOM）和溶解元素大多分布在低分子量部分，在胶体部分所占比例较低。锂、铷、锶、钼和铀表现出保守行为，而铜、铁、铬和钒具有非保守行为，并与DOM呈显著正相关，这表明即使在雨季，DOM也是雅瓜里贝河河口金属有效性的一个重要驱动因素。
