The Effects of Catchment Soils and Land-use on the Relationship between Organic Matter with Chlorine Decay and THMFP / Hur jordart och markanvändning i avrinningsområdet påverkar sammansättningen av organiskt material, klorsönderfall och trihalometanbildningspotential
With significant problems caused by organics in drinking water, comprehensive knowledge of its concentration, character and reactivity in relation to catchment features and management is important. In a study reported here, six contrasting zero order catchments of the Myponga Reservoir, South Australia were selected to determine the impacts of catchment characteristics and land management practices on THM formation potential (THMFP) of aquatic DOM and the kinetics of chlorine decay. Runoff and sub-surface waters from these catchments were standardized in DOC concentration and then treated by alum coagulation. Chlorine decay tests and DOM characterization were performed and THMFP determined on standardized samples before and after alum treatment. The results showed that runoff and subsurface waters from catchments having clay soils and with native vegetation or grass, had lower THMFPs than waters from sandy soils with these vegetative types. Subsurface waters from two catchments with Pinus radiata had similar THMFP formation, regardless of marked variation in surface soil texture. Under standard conditions, the residual DOM in waters of the clayey soil catchments after alum treatment showed faster chlorine bulk decay rates than of the corresponding sandy soil catchments. Organics in water from clay catchments were more difficult to remove by alum coagulation.