Apportionment of sources of polychlorinated dibenzo-p-dioxins and dibenzofurans by a chemical mass balance model

A chemical mass balance (CMB) model is developed and used to identify sources of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in three sets of sediment samples from the Housatonic River, Connecticut, Lake Huron, and the Baltic Sea. Various combustion sources and manufacturing processes, such as municipal waste incineration, coal and wood burning, and pentachlorophenols (PCPs), were considered possible sources of PCDD/Fs. Source fingerprints were taken from the literature. Our results indicate that air-particulates (SRM 1648), coal-fired power plants, municipal incinerators, and PCPs contribute significantly to the measured concentrations of PCDD/Fs. The relative errors for χ2 equal to the number of degrees of freedom, and the multiple correlation coefficient R2, are used to determine the best fits of the calculated to the measured PCDD/F homolog profiles. The average relative errors are 50.4, 49.8, and 40.6% (d.f. = 7, 8, 7) for the Housatonic River, Lake Huron, and the Baltic Sea, respectively. The average multiple correlation coefficients are 0.740, 0.693, and 0.842 for the Housatonic River, Lake Huron, and the Baltic Sea, respectively. Coal burning was the major source of PCDD/Fs before 1955 in the U.S., and 1970 in Europe, and municipal incinerators thereafter. Atmospheric transport may affect the PCDD/Fs profiles in the sediment. Biodegradation in the sediment is assumed to be negligible due to the long half-lives of these compounds.