Spatial and Temporal Behavior of Soluble Manganese at the Sediment–Water Interface in the Riogrande II Reservoir in Colombia

Abstract

The behavior of manganese (Mn) at the sediment-water interface in bodies of water such as lakes and reservoirs is dependent on physicochemical factors such as pH, redox potential-Eh, organic matter, specific conductance, and the presence of organic and inorganic complexes. These allow the mobilization of Mn from the sediment to the water column and promote its precipitation as Mn oxyhydroxide. For the Riogrande II reservoir in Colombia (2550 m), it was found that redox potential-Eh below 1350 mV is not appropriate for oxide stability. The availability and mobility of these oxides are more associated with organic complexation and desorption from sediments when the pH changes from neutral conditions to slightly acidic conditions (6.0). However, when the lower gates of the reservoir are opened during the dry season, the entry of oxygenated bottom currents most likely increases the dissolved oxygen (DO) and redox potential-Eh. Similarly, the increase in soluble Mn at the intake tower during the dry season is more associated with desorption than with reductive dissolution.The primary objective of this study is to determine the main physicochemical factors favoring Mn remobilization from sediment to the water column and its relation to the operating mechanisms of the intake water tower of the Riogrande II reservoir.One of the most notable results of this study is the observation that the operating mechanisms of the Riogrande II reservoir not only affect the type of water that is captured but also influence the geochemical processes at the bottom of the reservoir and in the sediment.The results of this study highlight the influence of hydraulic processes on surface water bodies as regards the dynamics of metal remobilization, the generation of pollution into the water column, and the increasing costs of treatment and purification in reservoirs in high mountain areas in tropical countries.

Macrobiont: Cradle for the Origin of Life and Creation of a Biosphere

“…Some transition metal elements are more easily solubilized under reduced conditions, such as Fe 2+ , whereas others are more readily brought into solution under high Eh, such as Mn 4+ . In practice, the behavior of Mn in natural aqueous environments is dependent on physicochemical factors such as pH, redox potential (Eh), organic matter, specific conductance, and the presence of organic and inorganic complexes [ 62 ]. The same factors also need consideration with the other transition elements.…”

Multivariate tools to investigate the spatial contaminant distribution in a highly anthropized area (Gulf of Naples, Italy)

“…These contaminants are usually generated by tannery industries operating in the Sarno plain (De Pippo et al 2006 ; Albanese et al 2013 ). Nevertheless, natural processes related to the physical–chemical condition and hydrodynamic regime determined in the near shore area might also affect this contamination pattern, where pH and salinity are appropriate, iron and manganese oxides coagulate the fastest (Singh et al 2009 ; Salazar et al 2015 ). This occurrence could accelerate the deposition of some siderophilic and/or some chalcophilic metals as Ni and As, which resulted abundant in the sediment of this track of Torre Annunziata.…”