engleski

Contaminant dispersion and source identification in small rivers, investigated on example of Radonja River, Croatia

Assessment of selected (trace) elements and nitrate along the 26.7 km long Radonja River (Croatia) was examined with the purpose of testing the ability for small rivers to serve as a model for identification of sources and dispersion of common environmental contaminants. The Radonja River rises and flows through specific geological region of the Petrova Gora Mt. (507 m a.s.l.). It is located in the middle part of Croatia, with the Vojnić town (~5, 000 inhabit.) as the largest settlement along the whole river course. Two sampling campaigns, covering high and low water flow, were conducted at 13 sampling locations. Concentrations of 23 elements in filtered and unfiltered samples were analysed using HR ICP-MS, while second campaign included also analysis of nitrates. Concentrations of most elements were higher during second sampling campaign in both fractions, when water level was low. Concentrations of majority of elements significantly increased downstream of Vojnić town, whose industrial and sewage waters are discharged into the river. In the whole lower river course concentrations of those elements remained high, indicating significant anthropogenic influence, and absence of self-purification process. However, there are some exceptions like Fe and Mn, whose concentrations are highest in the uppermost part of the river in the Petrova Gora Mt. and are caused by rock composition and ore occurrences in this mountain. Concentrations of nitrates in the uppermost part of the river, which is almost uninhabited, are very low (<0.5 mgL-1). Downstream Vojnić town they increase to over 3.5 mgL-1 and remain approximate at this value up to confluence with Korana River. Nitrates served as a very good tracer to identify Vojnić town and other downstream smaller, mostly agricultural settlements as pollution sources.

Radonja River (Croatia) ; water ; heavy metals ; nitrates ; pollution source identification

nije evidentirano