Chemical composition of black-watered rivers in the western Amazon Region (Brazil)

Abstract

A maioria das investigações sobre a química da águas na Amazônia é focada nos rios Solimões, Amazonas e Negro e o conhecimento sobre a composição química dos pequenos tributários é restrita a dados pontuais. Esses pequenos rios que apresentam, na maior parte das vezes, apenas aportes de suas bacias de drenagem, são muito importantes para entender os mecanismos controladores da química dos grandes rios da região. Com esse objetivo foi determinada a composição química dos principais afluentes de águas pretas do rio Solimões na Amazônia Ocidental Brasileira durante o período de águas baixas. Os dados revelam que a química das águas pretas é altamente variável e fortemente influenciada pelo ambiente geológico local: a bacia do Badajós é quimicamente mais diluída; a bacia de Coari apresenta alto conteúdo de SiO 2 , enquanto os lagos menores têm maior pH, condutividade, Ca 2+ , Mg 2+ e Sr, mas inferiores aos do rio Solimões. A composição química da água é compatível com a pouca erosão e com o ambiente altamente lixiviante da Amazônia onde os elementos mais solúveis são rapidamente removidos.Most investigations addressing Amazonian water chemistry are focused on the Solimões, Amazonas and Negro rivers. Knowledge of the chemical composition of their smaller tributaries is restricted to some few, punctual data. The smaller rivers, that only present inputs from their catchments, are very important to understand the overall mechanisms controlling the chemistry of larger rivers of the region. With this objective the chemical composition of the principal Solimões river black-watered tributaries in the western Brazilian Amazon during the low water period were determined. The data reveal the black water chemical composition to be highly variable and strongly influenced by the local geological environment: the Badajós basin being chemically more diluted; the Coari basin presenting higher SiO 2 contents, as well as smaller lakes having higher pH, conductivity, Ca 2+ , Mg 2+ and Sr, yet not as much as those found in the Solimões river. The chemical composition of these waters is compatible with the low physical erosion and the region's highly leached tropical environment from which most soluble elements were quickly removed.

Otolith geochemistry in young‐of‐the‐year peacock bass Cichla temensis for investigating natal dispersal in the Rio Negro (Amazon – Brazil) river system

“…1). The chemical composition of the water in the Negro River and its tributaries is highly variable and strongly influenced by forest characteristics and geological location (Horbe & Santos 2009). Within the NRB, black water with high acidity is predominant (Stallard & Edmond 1987).…”

Distribution of Metals in the Waters and Sediments of Rivers in Central Amazon Region, Brazil

“…In the Amazon, three types of waters can be identified: whitewaters with near-neutral pH and that contain large amounts of particulates; blackwaters that are acidic and rich in organic matter; and clear waters that have physicochemical characteristics between white and blackwater rivers. [1][2][3] Amazonas River is among the world's largest in terms of drainage area (6 × 10 6 km 2 ), with 20% of the flow of water from the land to the ocean. Itacoatiara is the third most populous municipality in the State of Amazonas, with an area of 8,891,906 km 2 and a hot, rainy and humid climate.…”

“…6 Several studies of metal transport have been conducted in the Amazon region, but most have been centered on the main rivers, especially the Negro, Solimões, Madeira and Amazonas River. 2,3,[7][8][9][10][11][12][13] Considering the land use in this region and since the Amazon River carries annually around 600 million tons of sediment to the ocean, the evaluation of metals transportation in the main tributaries of white and blackwaters from under-investigated regions are of great relevance to monitor the vulnerability of aquatic life and because these shall contribute to a significant fraction of metals exported to the ocean. This study aimed determination of total, dissolved and particulate metals concentration in freshwater and sediments of the rivers from Central Brazilian Amazon.…”

Assessment of surface water in two Amazonian rivers impacted by industrial wastewater, Barcarena City, Pará State (Brazil)

“…Therefore, these results show that the chemical characteristics of water drained into the Curuperê River from these sources were not altered by the discharge of industrial wastewater. 52,53 Table 2 also presents the physicochemical results and dissolved metal concentration obtained for the point after discharge of industrial wastewater (IR1) into the Curuperê River. At this point, the levels of acidity (pH 2.6), EC (2195.0 µs cm -1 ), SALT (1.22 mg L -1 ), TDS (1091.0 mg L -1 ), NH4-N (1740.0 mg L -1 ), SO4 (1900.0 mg L -1 ), Al (2.742 mg L -1 ), Fe (10.687 mg L -1 ), Mn (0.343 mg L -1 ) and Zn (0.398 mg L -1 ) were much higher than the ones recorded from the sources and suggest the inefficiency or absence of physical and chemical treatments of the effluents before being transported into the environment.…”