Bottom sediments play a fundamental role in the eutrophication process because they are one of the most active compartments in the biogeochemical cycle of nutrients. In Ushuaia city, Tierra del Fuego, Argentina, sewage effluents have been discharged into natural watercourses without treatment for many years. Organic matter has been introduced until 2016 when improvements in sewage infrastructure were done. The quality of surface sediments from three watercourses with different degree of impact has been studied taking into account contrasting hydrological periods. pH, organic carbon (OC), total nitrogen (TN) and soluble reactive phosphorus (SRP) were measured in austral autumn and spring between 2013 and 2018 in three sections of each watershed. Nutrient content in sediments of upstream sites derives from the contribution of Nothofagus spp. forests through litter-fall. Middle and downstream sites were the most affected by wastewater discharges evidencing that fluvial sediments act as a receptor of the allochthonous organic loads. Particularly, sediments of Buena Esperanza Stream had the lowest mean pH (5.44) and the highest mean concentrations of OC (42.95 mg g⁻¹), TN (2.53 mg g⁻¹) and SRP (0.067 mg g⁻¹), along with the lowest mean annual flow and the largest urbanized area. No differences between hydrological periods were found, although TN and SRP contents were higher in autumn than in the snowmelt season. Minimal differences in nutrients between before and after infrastructure improvement were found. Even when external contributions have been decreased, more time will be necessary to reduce eutrophic conditions of fluvial sediments in southernmost Patagonia.

底部沉积物在富营养化过程中起着基本作用，因为它们是营养物生物地球化学循环中最活跃的隔室之一。在阿根廷火地岛的乌斯怀亚市，污水未经处理已排入天然水道已有多年。直到2016年污水处理基础设施得到改善后，才引入有机物。考虑到不同的水文时期，研究了三种影响程度不同的水道的地表沉积物的质量。在2013年至2018年的秋季和春季，每个分水岭的三个部分分别测量了pH，有机碳（OC），总氮（TN）和可溶性反应性磷（SRP）。上游站点沉积物中的养分含量来自Nothofagus spp。凋落的森林。中下游地区受废水排放影响最大，表明河流沉积物是异源有机物负荷的受体。特别是，Buena Esperanza Stream的沉积物具有最低的平均pH（5.44）和最高的OC（42.95 mg g ^-1），TN（2.53 mg g ^-1）和SRP（0.067 mg g ^-1）的平均浓度），以及最低的年平均流量和最大的城市化区域。尽管秋季的TN和SRP含量高于融雪季节，但没有发现水文时段之间的差异。发现基础设施改善前后的养分差异最小。即使减少了外部影响，也将需要更多时间来减少最南端的巴塔哥尼亚河流沉积物的富营养化状况。