engleski

Importance of real trace metal concentrations monitoring: Examples of Krka River and groundwater of Mala Mlaka water well (Zagreb), Croatia

Krka River is a middle Adriatic, typical groundwater-fed karstic river. Freshwater part is 50 kilometres long, partly protected as a national park because of tufa cascades, but with detected anthropogenic influence. Krka River has been a subject of numerous studies. However, results of trace metal analyses were very variegated, from not enough sensitive measurements resulting in “lower than” definitions to overestimated concentrations obtained as the result of wrong sampling procedures and pollution during the measurements procedures. Mala Mlaka, a biggest Zagreb’s water well (about 2200 L/s) is regularly checked on the concentration of relevant parameters, based on levels proscribed by law concerning drinking water. The methods used for regular monitoring are not enough adapted to determine the real concentration of trace ecotoxic metals. Using clean sampling techniques and precise laboratory methods we obtained concentrations up to two orders of magnitude lower than published in official monitoring reports. For mercury and cadmium the reasons for discrepancies were mostly in not enough sensitive instrumental methods applied, while for zinc and copper the grounds mostly lied in pollution during sampling and measuring. For lead the reasons could be a combination of the mentioned reasons. Therefore it is essential to point out the importance of real trace metal concentration determination, particularly in such special water systems. Although the found concentrations might be much bellow the concentrations allowed by the law, that approach would ensure detection of dangerous trends and serve as an useful trigger for early warning procedure, enabling a real chance for on time actions towards protection of the water bodies.

trace metal concentrations in water systems; early warning

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