Distribuição e variabilidade de nutrientes em bacias hidrográficas da Amazônia: uma análise bibliométrica

Abstract

The excessive presence of nutrients in water triggers a process known as eutrophication, which can affect its quality and lead to ecological imbalance, generating significant environmental impacts. Human activities such as agriculture, livestock farming, mining, and urbanization may be related to the increase of nutrients in the Amazon rivers. Despite the severity of this issue, studies on the increase of nutrients in the Amazon basin are still scarce in the scientific and academic community. The objective of this work was to explore databases like Scopus and Web of Science to synthesize information on nutrient concentrations (N and P) in the Amazon basin. After searching databases using selected keywords and following the three phases of article selection, 40 relevant articles were chosen for the bibliometric review of literature on the topic. The reviewed literature presented results on nitrate, nitrite, ammonium, and phosphate, with nitrate being the most frequently analyzed nutrient in 33 published works, followed by phosphate in 28 studies, ammonium in 26, and nitrite in nine. The study revealed higher average concentrations for nitrate, at 20.28 mg/l, and for phosphate, at 8.03 mg/l, indicating potential areas of interest for future eutrophication research. The mainstem of the Amazon River was the most studied area, appearing in 11 published articles, followed by the Negro, Solimões, and Orinoco rivers, each with seven studies. Data scarcity was identified in areas of the Tapajós, JiParaná, Trombetas, Araguaia, Madre de Dios, Tocantins, Madeira, and Xingu rivers, indicating a lack of information on nutrient concentrations in the sample coverage of collected data. This study provides an important review of nutrient concentrations in the Amazon rivers, emphasizing the need for further research to understand nitrogen and phosphorus concentrations, especially in the main sub-basins of the Amazon (Xingu, Madeira, Tapajós, and Tocantins, Purus), located in deforestation arc areas experiencing greater anthropogenic pressure with few or no studies presented. Understanding these nutrient patterns is essential to protect aquatic ecosystems and promote human health in the Amazon, aiming to guide conservation policies and sustainable management of water resources in the region.