Chemical speciation in mining affected waters: the case study of Asarel-Medet mine

Abstract

The inorganic chemical species in Maresh and Luda Yana rivers affected by the Cu- Mo Asarel-Medet mine, Bulgaria were determined during a low-flow and a high-flow period. The mining activities, the weathering and the oxidation processes strongly influenced the physicochemical processes in the whole water system. The main pollution source was a small lake receiving the acid effluents of the mining activities. High levels of SO4(2-), Cu, Mg, Al, Mn and Fe were determined at the mining polluted and affected stations. Cu(2+) and CuCO3(0) species (1:1) were present in the reference waters and Cu(2+) and CuSO4(0) species (1:1) in the polluted and affected waters; Cu(2+) species was dominating downstream. Me(2+) followed by MeSO4(0) (Me = Mn, Zn, Cd and Pb), PbCO3(0) and PbHCO3(+) species as well as Fe(OH)2(+), Al(OH)4(-), Al(OH)2(+), Al(OH)3(0) were prevailing in the system. MeSO4(+) and Me(SO4)2(-) (Me = Fe, Al), Me(SO4)2(2-) (Me = Zn, Cd and Pb), Me(SO4)3(4-) (Me = Zn, Cd) and Cd(SO4)4(6-) species polluted and affected waters. The major elements K and Na were mainly Me(+) species, whereas Ca and Mg were Me(2+) and MeSO4(0) species in different ratios. The concentration of concentration of NO2(-), NO3(-) and NO4(+) species as well as complex phosphorous species such as H2PO4(-), FeHPO4(+), HPO4(2-), CaPO4(-), CaHPO4(0) and MgHPO4(0) were also calculated. The trace element concentrations decreased downstream due to dilution, sorption processes and precipitation, but the percentage of free metal species, which are more toxic, increased. An exception was iron and aluminum of which the dominant hydroxy colloidal and sulphate species were easily incorporated into the suspended phase.

Water Quality of Medium Size Watercourse Under Baseflow Conditions: The Case Study of River Sutla in Croatia

“…The site 1 was again proved as a good reference site, due to metal levels comparable even to pristine river Lena (Martin et al 1993), which has average discharge of 17,000 m 3 s -1 , and therefore also very high dilution capacity. Although the contaminated site 4 had somewhat higher concentrations of several metals, especially Cd and Pb, compared to agriculturally impacted Yamaska River in Canada (Cooper and Fortin 2010), its metal concentrations were still far below metal levels reported for highly contaminated rivers, such as Nanyang River in China contaminated by electronic waste (Wong et al 2007), or mining impacted rivers like Luda Yana in Bulgaria (Rabadjieva et al 2009). …”

Chemical speciation in fresh, saline and hyper-saline waters

“…The equations are valid for solutions of low ionic strength: I < 0.1 mol.kg -1 . Despite this limitation, the method is applied for both urban [2] and industrially [7,14] polluted natural waters, even for marine waters (I ∼ 0.7 mol.kg -1 ) [15], but the results are disputable in the latter case.…”

“…Surface waters of two different regions of Bulgaria were the subject of our previous monitoring and thermodynamic modeling studies [7,8]. The studied areas were chosen so as to include waters with different type (urban and mining) and level of pollution (reference stations registering the background in the examined region, the pollution sources and the affected areas), as well as surface waters of different ionic strength (fresh, saline and hyper-saline waters).…”

“…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].…”

“…It uses the thermodynamic formation constants of the different complexes as a primary database. This method is employed for modeling the chemical species of microelements in urban [2] or industrially [7,13] polluted natural waters. The ion interaction model is not limited to low ionic strength waters; its equations involve, however, a large number of semi-empirical parameters.…”