DBP formation potential of aquatic humic substances

Aquatic humic substances (AHSs) in water generate potentially harmful disin fection by-products (DBPs) such as haloacetic acids (HAAs) and trihalometha nes (THMs) during chlorination. AHSs from two Arkansas reservoirs were char acterized to define source, identify meta- dihydroxybenzene (m-DHB) structu res as probable DBP precursors, and evaluate predicted HAA and THM formatio n potentials. Elemental nitrogen content < 1 percent, phenol content > 0.5 mu eq/mg, delta(13)C values of -27(parts per thousand), and low yields of s yringyl phenols found by cupric oxide (CuO) oxidation suggest a pine tree s ource for the AHSs found in the Maumelle and Winona reservoirs in Little Ro ck, Ark. CuO oxidation yielded fewer m-DHB structures in Maumelle AHSs than in Winona AHSs. A higher 3,5-dihydroxybenzoic acids (3,5-DHBA) content cor related with increased HAA and THM formation potential. The 3,5-DHBA concen tration in Winona AHSs was similar to the range found in the AHSs extracted from deciduous leaf litter, twigs, and grass leachates.