Chemical speciation of inorganic pollutants in river–estuary–sea water systems

Abstract

Monitoring studies and thermodynamic modeling were used to reveal the changes of inorganic chemical species of some water pollutants (nutrients and trace metals such as Fe, Mn, Zn, Cu, Cd and Pb) inthe river-estuary-sea water system. The case studies were two rivers, Kamchiya and Ropotamo, representing part of the Bulgarian Black Sea water catchment area, and having different flow characteristics. There were no major differences in inorganic chemical species of the two river systems. NO3(-) and NO2(-) chemical species showed no changes along the river-estuary-sea water system. Concerning phosphates six different species were calculated and differences between the three parts of the systems were established. The HPO4(2-) and H2PO4(-) species were found to be dominant in river waters. The H2PO4(-) species quickly decreased at the expense of HPO4(2-) and Ca, Mg and Na phosphate complexes in estuary and seawater. Trace metals showed a great variety of chemical species. Fe(OH)2(+) species prevailed in river waters, and Fe(OH)3(0) species--in sea waters. Me2+ and MeCO3(0) (Me = Cu, Pb) and PbHCO3(+) were dominant in river waters, while Cu(CO3)2(2-) and PbCl(-) species appear also in sea waters. Cd2+ species prevailed in river and estuary waters, and CdCln(2-n) (n = 1-3) species, in seawater. Free Zn2+ species predominated in all systems but downstream their percentage decreased at the expense of Zn phosphates, carbonates,sulfates and chlorides complexes. Only free Mn2+ species were dominant along the systems.

Electrothermal atomic absorption spectrometric determination of cadmium in environmental samples with niobium wire preconcentration method

“…Tepavitcharova et al [25] have investigated the chemical speciation of inorganic pollutants (nutrients and trace metals such as Fe, Mn, Zu, Cu, Cd and Pb). In the study, free Cd 2þ ions are prevalent in river (97%) and estuary water (93%), whereas in sea waters chloride complexes CdCl 2À n (n ¼ 1-3) are dominant (5-58%).…”

“…Moreover, it would be considered that the physical adsorption and the interaction between the element cadmium and the niobium wire surface might also occur as the preconcentration mechanism. From the information in the literature [7][8][9][10][11][12][13][14][15][16][17][18][19][25][26][27][28][29], it is not clear which process is predominant for the adsorption of cadmium on the niobium wire. These processes are still being examined.…”

Microbial, physical and chemical properties of irrigation water in rice fields of Southern Brazil

“…For the pH, phosphorus, potassium and nitrogen variables this reduction is relevant, as high levels of these substances can be prejudicial to aquatic ecosystems (Smith 2003, Kim and Oh 2006, Sharma et al 2008, Tepavitcharova 2009.…”

Chemical speciation in fresh, saline and hyper-saline waters

“…Thus, they should be under permanent monitoring control. Usually, this control includes nutrients and trace metals as major inorganic pollutants [1,2].…”

“…Thus, thermodynamic modeling can be a useful tool for non-expensive and effective evaluation of inorganic chemical species in natural waters [2,7,8]. Two basic thermodynamic methods, differing in activity coefficient calculation of the species, have been developed -the ion association model [9,10] and the ion interaction model [11,12].…”