Naslov
Occurrence of Mn in alluvial aquifer as a consequence of surface – groundwater interaction in the Požega valley - Croatia

Autori
Marković, Tamara ; Larva, Ozren ; Brkić, Željka

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Book of Abstracts / Holysh, Steve ; Howard, Ken - Niagara Falls : IAH, 2012, 95-95

Skup
39th International Association of Hydrogeologists Congress

Mjesto i datum
Niagara Falls, Kanada, 16.09.2012. - 21.09.2012

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
manganese; geochemical processes; alluvial aquifer; Požega valley

Sažetak
The trace metal manganese (Mn) is ubiquitous in the environment and it can exists in different oxidation states, but the most widely occurring forms in the environment is soluble Mn (II) when reduced and insoluble Mn (IV) when oxidised. Naturally occurring Mn is commonly found in drinking water supplies and is essential for human health at low concentrations. Human exposure to excessive Mn concentrations can result in adverse human health effects. The behaviour and fate of Mn was studied in the Orljava River and in groundwater in alluvial aquifer in the Požega valley, where the high concentration of Mn was observed in groundwater at western part of the pumping site "Zapadno polje". Only four out of eighteen wells have concentrations of Mn above MCL (in Croatia is 50 ppb). The concentrations range from 60 to 1146 ppb in the water from wells, and from 19 to 244 ppb in the river water. The occurrence and concentration of Mn in the groundwater and the river water is controlled by many factors, among which colloidal geochemistry, water chemistry and microbiological activity are considered as most important ones. The study area is a part of the Pannonian basin and is located in the central part of northern Croatia. The Orljava River and its tributaries are depositing the sediments in the valley from the surrounding mountains. The surrounding mountains consist of magmatic, metamorphic and sedimentary rocks. The valley is built from alluvial and pond deposits. The aquifer is formed of gravel-sandy deposits and its thickness varies between 4 and 6 m. The pond deposits have high content of the manganese. During the regulation of the Orljava riverbed a few years ago, the sediments which contain high concentrations of Mn were uncovered. Mathematical model of groundwater flow and particle tracking confirmed the recharge of the aquifer by river in most hydrological conditions. Geochemical measurements and modelling discovered that the Mn has been entered into the aquifer by the river mostly absorbed on colloids (clays) and in soluble state. It was also determined that oxidative conditions prevail in the aquifer and the change of the pH is the driving force for the release of Mn in the water . The changing of the pH is a result of leaching of dissolved CO2 from the surface to the ground. The highest contribution was observed in autumn. The change of water level in the aquifer and infiltration of precipitation are driving forces of the CO2 leaching.

Izvorni jezik
Engleski

Znanstvena područja
Rudarstvo, nafta i geološko inženjerstvo

POVEZANOST RADA