Determination of Partition Coefficients of Metals in Natural Tropical Water

Abstract

The values for the partition coefficient (K d ) were calculated for Ca, Mg, Cd, Cr, Cu, Fe, Mn, Pb, Ni, and Zn at 19 sites in the Capivara hydroelectric reservoir in Brazil. It was found that the relative values of K d follow the order: Cr > Mn > Fe > Cu > Zn > Ni > Pb > Ca > Cd, differing from the values reported for K d in aquatic systems in the northern hemisphere. A hierarchical cluster analysis and linear correlations showed that Cr is strongly associated with Fe and Cu, and that Cd is the only metal found in complexation with organic matter, explaining its higher solubility.

Distribution Coefficient and Metal Pollution Index in Water and Sediments: Proposal of a New Index for Ecological Risk Assessment of Metals

“…For Pb, the Texcoco water bodies showed a Log(K d Pb ) of 2.71, while [56] reported a value of 5.1. On the other hand, [16] reported that Log(K d d) values for Cr, Cu, Ni, and Zn in Lake Capivara were higher than those calculated by [56]. Despite lakes Capivara and Texcoco being tropical water bodies, the latter is influenced by a Solonchak soil.…”

“…MPI represents the geometric mean concentration of metals in a given compartment of the water body, either water, sediments, or both; K d indicates the compartment where individual metals are contained. When used together, these two parameters support risk assessment for the aquatic biota [5,10,16,18,22,23].…”

“…Barreto et al [16] indicate that less than 200 studies in the literature report K d values for natural aquatic environments, located mostly in the northern hemisphere. Li et al [55] estimated the distribution coefficients of five metals in three temperate lakes of China collapsed by mining operations (Cd, As, Pb, Zn, and Sb).…”

“…Barreto et al [16] determined the distribution coefficients in the Capivara reservoir in Brazil, a tropical water body. These authors worked with Cd, Cr, Cu, Fe, Mg, Mn, Ni, Pb, and Zn, obtaining the following Log(K d ) values: 3.80, 6.98, 5.86, 6.2, 3.81, 6.37 5.6, 5.49, and 5.84, respectively, which indicate that Cr, Cu, Fe, Mn, Ni, Pb, and Zn are associated mostly with the solid phase.…”

“…Sediments are essential components of lakes, providing food for benthic organisms and accumulating multiple pollutants such as pesticides; additionally, sediments are the most important reservoirs of metals in aquatic systems [1,10,14]. Over the past three decades, metals in water and sediments of freshwater ecosystems have been the focus of interest of several researchers [15][16][17]. Therefore, the development of evaluation methods to monitor metal pollution is essential.…”