Ecotoxicology assay for the evaluation of environmental water quality in a tropical urban estuary

Abstract Most studies evaluating the impacts of river pollution in the semi-arid region of Brazil have been geared towards physiochemical analyses, and investigations of the adverse effects of water pollution on associated organisms are scarce. This study aimed to evaluate the water quality in the Poxim river estuary in Aracaju, Sergipe throughout the dry and rainy season by evaluating the survival of the microcrustacean Mysidopsis juniae and physicochemical analyses. The evaluation of physiochemical parameters revealed a decrease in dissolved oxygen content in the rainy season. However, there was a significant reduction in microcrustacean survival in samples during the dry season, when the river flow is reduced and effluents become concentrated. These results suggest that pollutants received and carried by the waters of the Poxim River contribute to the reduction of environmental quality in the estuary, and this impact may vary according to dry and rainy patterns, that are uncertain considering the impacts of climate change on tropical regions.摘要 针对巴西半干旱地区河流污染影响的相关研究，大多聚焦于理化分析，而有关水污染对关联生物产生不利影响的调查则较为匮乏。本研究旨在通过监测微型甲壳动物俊氏米虾（Mysidopsis juniae）的存活率及理化分析，对巴西塞尔希佩州阿拉卡茹市波克辛河河口在旱季与雨季的水质状况进行评估。理化参数检测结果显示，雨季的溶解氧含量有所降低。然而，旱季样本中的微型甲壳动物存活率出现了显著下降，此时河流水量减少，污染物排放物浓度升高。上述结果表明，波克辛河水体接纳并携带的污染物，是导致该河口环境质量下降的原因之一；且此类影响会随旱雨季模式发生变化，鉴于气候变化对热带地区的影响，该模式的不确定性仍有待明确。