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 source s and manufacturing processes, such as municipal waste incineration, c oal and wood burning, and pentachlorophenols (PCPs), were considered p ossible sources of PCDD/Fs. Source fingerprints were taken from the li terature. Our results indicate that air-particulates (SRM 1648), coal- fired power plants, municipal incinerators, and PCPs contribute signif icantly to:the measured concentrations of PCDD/Fs. The relative errors for chi(2) equal to the number of degrees of freedom, and the multipl e correlation coefficient R-2, are used to determine the best fits of the calculated to the measured PCDD/F homolog profiles. The average re lative errors are 50.4, 49.8, and 40.6% (d.f. = 7, 8, 7) for the Housa tonic 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 1 970 in Europe, and municipal incinerators thereafter. Atmospheric tran sport 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. (C) 1997 Elsevier Science Ltd.