Hydrochemical characteristics of shallow groundwater in aquifer containing uranyl phosphate minerals, in the Köprübaşı (Manisa) area, Turkey

Abstract

The concentrations of uranium, iron and the major constituents were determined in groundwater samples from aquifer containing uranyl phosphate minerals (meta-autunite, meta-torbernite and torbernite) in the Köprübaşı area. Groundwater samples from wells located at shallow depths (0.5-6 m) show usually near neutral pH values (6.2-7.1) and oxidizing conditions (Eh = 119-275 mV). Electrical conductivity (EC) values of samples are between 87 and 329 lS/cm -1 . They are mostly characterized by mixed cationic Ca dominating bicarbonate types. The main hydrogeochemical process is weathering of the silicates in the shallow groundwater system. All groundwater in the study area are considered undersaturated with respect to torbernite and autunite. PHREEQC predicted UO 2 (HPO 4 ) 2 2-as the unique species. The excellent positive correlation coefficient (r = 0.99) between U and PO 4 indicates the dissolved uranium in groundwater would be associated with the dissolution of uranyl phosphate minerals. The groundwater show U content in the range 1.71-70.45 lg/l but they are mostly lower than US EPA (2003) maximum contaminant level of 30 lg/l. This low U concentrations in oxic groundwater samples is attributed to the low solubility of U(VI) phosphate minerals under near neutral pH and low bicarbonate conditions. Iron closely associated with studied sediments, were also detected in groundwater. The maximum concentration of Fe in groundwater samples was 2837 lg/l, while the drinking water guidelines of Turkish (TSE 1997) andUS EPA (2003) were suggested 200 and 300 lg/l, respectively. Furthermore, iron and uranium showed a significant correlation to each other with a correlation coefficient (r) of 0.94. This high correlation is probably related to the ironrich sediments which contain also significant amounts of uranium mineralization. In addition to pH and bicarbonate controlling dissolution of uranyl phosphates, association of uranyl phosphates with iron (hydr) oxides seems to play important role in the amount of dissolved U in shallow groundwater.

Hydrogeochemical investigation of groundwater in shallow coastal aquifer of Khulna District, Bangladesh

“…causes infiltration problem (Ayers and Westcot 1985). MAR greater than 50 is considered harmful and unsuitable for irrigation purposes (Kacmaz and Nakoman 2010;Islam et al 2016b). About 70% of the studied water falls in this category and remaining 30% falls in suitable category in case of magnesium hazard (Table 4).…”

Remobilization of U and REE and the formation of secondary minerals in oxidized U deposits

“…Dall'Aglio et al (1974), Murakami et al (1997), and Kaçmaz and Nakoman (2009) have also analyzed waters, which are undersaturated with respect to uranyl phosphates and stated that higher U and P concentrations would be needed for precipitation. However, Murakami et al (1997) showed that uranyl phosphates can form by local saturation at the interfaces of apatite (as P source) and sklodowskite (U source).…”

Groundwater Quality of Some Parts of Coastal Bhola District, Bangladesh: Exceptional Evidence

“…In this research, the water samples were collected at depths of 260.0-430.0 m (Table 1). MAR values < 50 are considered appropriate for irrigation, but values >50 are considered inappropriate [88]. Considering the designed value of MAR, all the collected samples were in the safe zone and could be used for agricultural purposes.…”