engleski

Characterization of Organic Matter in Wet Precipitation in Croatia

Organic matter, especially its reactivity and physico-chemical properties, play a crucial role in complex biogeochemical processes in aquatic environments. It is known that atmospheric input of substances in limnological and marine ecosystems can be dominant on both, the regional and the global scale, and plays an important role in controlling the level and the dynamics of persistent organic pollutants in aquatic systems. The dissolved organic carbon (DOC) is the most relevant and most frequently used collective parameter for organic matter content. Surface active substances (SAS) contribute to the amount of organic compounds and play a role in the control of atmospheric processes, enhancing the potential of rain drops for washing out organic matter from the atmosphere and mobilizing micropollutants on the global level. In this work the dissolved organic carbon and content of surface active compounds have been measured in the samples collected in two cities in Croatia, one in continent (Zagreb) and the other in coastal zone in the Middle Adriatic (Šibenik). DOC concentrations in samples from Zagreb were in range of 0.67–4.03 mgC/L with average concentration of 1.93 ± 0.76 mgC/L, in samples from Šibenik in range of 0.44–4.13 mgC/L with average concentration of 1.83± 0.83 mgC/L and are similar to those measured in other samples of continental rainwater in the northern hemisphere. The concentrations of SAS in samples from Zagreb ranged from 0.055 to 0.45 eq. Triton-X-100 mg/L with average concentration of 0.14± 0.06 eq. Triton- X-100 mg/L. SAS fractions were of a similar range in Šibenik (0.02–0.60 eq. Triton-X-100 mg/L) with an average concentration of 0.11 ± 0.06 eq. Triton-X-100 mg/L. Additional characterization of organic matter was performed by using electrochemical probes, namely lead and cadmium ions representing major heavy metal pollutants in the environmental water system. The adsorption of organic molecules can influence the electrode processe of metal ions to a different degree ; one can expect inhibition of electrode process, accumulation of metal ion in the adsorption layer or formation of layer transparent for metal transfer. The interaction of model organic substances representative for the rain water samples like humic acid and hydroxybuttyric acid with lead and cadmium ions was followed too. The characterization of organic substances in investigated samples was evaluated by comparison with selected model substances.

surface active substances ; organic matter ; dissolved organic carbon ; electrochemical methods ; wet precipitation

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