Relationships between Measures of NOM in Quabbin Watershed

Abstract

Natural organic matter (NOM) in water sources differs in terms of both character and concentration. Water treatment processes and the aesthetic quality of water may be influenced by NOM concentration and character. NOM is also related to nutrient cycling and availability and the general trophic state of an aquatic ecosystem. Quabbin Reservoir is the primary drinking water source for metropolitan Boston, Massachusetts. Measures of NOM present in samples collected from the watershed included, but were not limited to, total organic carbon (TOC), dissolved organic carbon (DOC), ultraviolet absorbance (UVA), and trihalomethane formation potential (THMFP). Samples were collected at the mouths of the 12 major Quabbin tributaries and from a horizontal transect of six sites within the reservoir. A variation was found in the relationships between measures of NOM from the reservoir and tributary samples. Regression analyses showed positive linear relationships between DOC and UVA, THMFP and TOC, and THMFP and UVA. Relationships between measures of NOM in the reservoir samples were weaker than those obtained for the tributary samples. These weaker relationships were attributed to the low concentrations and narrow ranges of measures of NOM in the reservoir and the overall complexity of the aquatic system.