All drinking water supplies contain some background organic matter. Usually these organics are naturally-occurring plant product or their derivatives. In the early 1970s NOM became a focus of concern as its central role in the formation of potentially carcinogenic disinfection byproducts (DBPs) was recognized. Different watersheds are known to result in waters with different levels of NOM, however the factors that lead to these differences are not well understood. It is now clear that more attention must be paid to the upstream processes that give rise to NOM in raw waters.
Total organic carbon (TOC) is one of the most widely used measures for quantifying the amount of NOM in water. Impacts of anthropogenic changes within a watershed effect NOM quantity and quality. To understand what watershed characteristics most affect NOM quantity and quality, and therefore the threat of increased DBPs, we are seeking out long term, wide spanning data on TOC concentrations.
This project has initiated the development of a comprehensive database on TOC in raw waters. TOC data has been collected and analyzed from existing database sources (STORET, USGS stations) in order to describe large-scale trends across ecoregions and develop empirical relationships with land use types. TOC and DBP data has been collected from participating water treatment plants, also spread across the nation, to analyze the observed TOC trends against the water quality management of the water plants. Results are presented first as visual spatial and temporal trends of existing TOC values across the nation, second as a correlation of land cover types with TOC values, and third as the potential to more mechanistically explain observed TOC values and associated DBP levels at a watershed scale. |
