This study investigated surfactant levels in the sediment of Itanhaém Estuary through colorimetric methods with methylene blue active substances (MBAS). Samples were collected with a Van Veen bottom sampler at eight sampling points during autumn, winter, and spring of 2015. The results demonstrate growing detergent deposition in the sediment of the estuary. Surfactant concentration was higher (16.18 μg MBAS g⁻¹) around the sewage treatment plant (STP) than in the estuary in autumn, after the vacation/summer season when the population of the city had increased due to tourism. There was a significant (p < 0.05) reduction in detergent concentration (to 14.94 μg MBAS g⁻¹) in winter, after school vacation, while in spring the surfactants concentration for the STP was high only for the sampling points nearer the ocean. Surfactant concentrations differed significantly among sampling points (p < 0.05), with them being higher at those closer to the STP. Enrichment with high loads from anthropogenic sources associated with urbanization and tourism was responsible for the greater surfactant concentrations in areas near the STP. In conclusion, more efficient treatment of domestic effluent of the city of Itanhaém is needed, as is the control of clandestine discharge into the river since the accumulation of detergents in sediment can have harmful effects on aquatic life.

中文翻译：

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巴西圣保罗伊坦哈姆河口沉积物中的表面活性剂

本研究通过使用亚甲蓝活性物质 (MBAS) 的比色法研究了伊坦哈埃姆河口沉积物中的表面活性剂水平。在 2015 年秋、冬和春季期间，使用 Van Veen 底部取样器在 8 个采样点采集样品。结果表明，河口沉积物中的洗涤剂沉积量不断增加。秋季，由于旅游导致城市人口增加，在假期/夏季之后，污水处理厂 (STP) 周围的表面活性剂浓度 (16.18 μg MBAS g ^{-1 ) 高于河口。}去污剂浓度显着降低（p  < 0.05）（降至 14.94 μg MBAS g ^-1) 在冬季，放学后，而在春季，STP 的表面活性剂浓度仅在靠近海洋的采样点上较高。表面活性剂浓度在采样点之间存在显着差异（p  < 0.05），在靠近 STP 的点表面活性剂浓度较高。与城市化和旅游相关的人为来源的高负荷富集是导致 STP 附近地区表面活性剂浓度较高的原因。总之，需要对伊坦哈姆市的生活污水进行更有效的处理，因为清洁剂在沉积物中的积累会对水生生物造成有害影响，因此需要控制向河流的秘密排放。