Abstract
Water supply of Riga City uses water from the river Daugava, lakes Baltezers as well as deep well groundwater as drinking water. Due to chlorination of drinking water before use, inhabitants health may be at risk due to trihalornethanes and some organic pollutants. The objective of this study was to determine the level of pollution of drinking water and possible health risk. Pollutants were determined with previous solid phase microextraction (on fibre coated with polidirnethylsilox ane) or pentane extraction of chemical substances by use of gas chromatography and for benzo(a)pyrene by spectrofluorimetry The summary concentration of thrihalornethanes (bromoform, chloroform, bromodichlorornethane, dibromochloromethane) ranged from 3.4 ug/drn' to 304.4 etg/dm3 (maximum allowable concentration - MAC 100 μg/dm-' according to water standards in Latvia), summary lrichloroethene and tetrachloroethene occurred in the concentration from I .O ug/drn' to 13.4 ug/dm' (MAC = I O ug/drri') The level of aromatic hydrocarbons benzene and toluene was below 0.2 ug/drrr' (MAC = I μg/dm'). The concentration of benzo(a)pyrenc was below 0.002 ug/drrr' (MAC= O.Ol ug/drrr'). Fluctuations of concentration were found to depend on the season and place of sampling. The results confirmed an occurrence of risk due lo the impact of trihalomethanes to health. Therefore, water ozonation has been planed to replace chlorination with ozonation in Riga City.
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