Although wetlands in temperate regions have been studied for their pollutant remediation potential, the sediment and nutrient retention capacity of natural wetlands in tropical environments remains understudied. In this study, a mass balance approach was used to estimate the amount of sediment and nutrients retained at 40 different study sites located in four natural riverine wetlands in Southwest Ethiopia. Awetu and Boye wetlands retained a substantial amount of total suspended solids (TSS) and nutrients whereas Kofe and Kito wetlands had a net release. Overall, the amount of TSS retained by the four wetlands was estimated to be 6266.5 kg/ha/day. On the other hand, the net retention of Total Organic Nitrogen (TON) and Total Phosphorous (TP) was estimated to be 37.6 kg/ha/day and 40.9 kg/ha/day, respectively. A stepwise multiple regression analysis revealed that anthropogenic activities such as farming, grazing, waste dumping and clay mining were the main variables that negatively affected the retention of TSS and nutrients. Farming alone explained 58% of the variation in TSS retention and cattle grazing explained 25% of the variation in TON retention. Therefore, watershed management interventions considering the mitigation of anthropogenic activities could be considered to reduce sediment and nutrient input and release.

中文翻译：

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埃塞俄比亚西南部天然河流湿地的沉积物和养分保留能力

尽管温带湿地的污染物修复潜力已得到研究，但热带环境中天然湿地的沉积物和养分保留能力仍未得到充分研究。在这项研究中，使用质量平衡方法来估计位于埃塞俄比亚西南部四个天然河流湿地的 40 个不同研究地点的沉积物和养分保留量。Awetu 和 Boye 湿地保留了大量的总悬浮固体 (TSS) 和养分，而 Kofe 和 Kito 湿地则有净释放。总体而言，四个湿地保留的 TSS 量估计为 6266.5 公斤/公顷/天。另一方面，总有机氮 (TON) 和总磷 (TP) 的净保留估计分别为 37.6 公斤/公顷/天和 40.9 公斤/公顷/天。逐步多元回归分析显示，耕作、放牧、垃圾倾倒和粘土开采等人为活动是对 TSS 和养分保留产生负面影响的主要变量。仅农业就可以解释 58% 的 TSS 保留变化，而放牧可以解释 25% 的 TON 保留变化。因此，考虑减轻人为活动的流域管理干预措施可以考虑减少沉积物和养分的输入和释放。