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Aromatic carbon is considered one of the most reactive molecular moieties with respectto trihalomethanes (THM) formation during water chlorination. Studies have shown thatultraviolet absorbance at 254 nm (UVA254) is a good proxy for aromatic content indissolved organic carbon (DOC). Thus, specific UVA254 (SUVA254), which is equal tocarbon normalized UVA254, has been widely used as a measure for aromatic organiccarbon content and trihalomethane formation potential. However, recent studies havequestioned the reliability of using SUVA254 to predict THM formation because nitrate,bromide and non-reactive conjugated double bonds of organic carbon under chlorinationalso absorb UVA at 254 nm. The authors hypothesize that the difference in SUVA254before and after chlorination (SUVA254) should be proportional to the formation ofTHM if SUVA254 measures the amount of THM reactive sites in DOC. The authorsexamined DOC originating from agricultural soils in the Sacramento-San Joaquin Deltaand from 35 river sites in the Sacramento-San Joaquin watershed. The relationshipsbetween SUVA254, UVA254/DOC and SUVA254 versus specific THM formationpotential were evaluated. Results indicated that the correlation coefficients ofUVA254/DOC-STHMFP and SUVA254-STHMFP are slightly better than SUVA-STHMFP. Also, all these parameters in terms of UVA at 272 nm provide slightly bettercorrelation than UVA at 254 nm. Includes 13 references, table, figures.

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Edition: Vol. - No. Published: 11/15/2004 Number of Pages: 13File Size: 1 file , 2.9 MB