Apportionment of sources of PAHs and PCDD/FS in aquatic sediments by a chemical mass balance model

The main purpose of this study was to identify and apportion the possible sources of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in aquatic sediments by a chemical mass balance (CMB) model. Nine sediment cores collected in 1995 from the lower Fox River and Green Bay, Wisconsin, were analyzed. {dollar}sp{lcub}210{rcub}{dollar}Pb and {dollar}sp{lcub}137{rcub}{dollar}Cs dating was used to determine historical trends of PAH inputs, and elemental carbon particle analyses, reflecting combustion of coal, wood, and petroleum, were used for comparison with the CMB modeling results. Coke burning, highway dust, coal gasification, and wood burning are likely sources of PAHs to the lower Fox River, and similarly for Green Bay, except that coal gasification PAHs are less likely there.; Coke oven emissions (CB) are 50 to 90% of total PAHs for Fox River cores, and this fraction decreases from 1930 to 1990, except in core FR-A. The overall highway dust (HWY) contribution in Fox River cores is between 10 and 50%, and it increases from 1930 to present. Coal gasification (CWG) contributes with less than 10% except in core FR-A. The contribution of wood burning has changed from {dollar}<{dollar}4% in 1950 to 2-15% in 1995. There is evidence of aerobic biodegradation of benz(a)anthracene (BaA) and anthracene (AN) with half-lives of 0.9 and 1.75 yr, respectively.; By contrast, coke oven emission (CB) is less important to Green Bay than to Fox River sediments. CB slightly increased from the early 1960's to mid-1980's. The total PAHs concentration reached a maximum in the 1980's for GB-A, GB-B and GB-E. Highway dust (HWY) has increased since the 1960's to the early 1990's for GB-A, GB-C, and GB-F, and is opposite to the trend in GB-B and GB-E where HWY is less important than CB. HWY is the major source in GB-A, GB-C, and GB-F, and wood burning (WB) is a likely source to this study area. The CB contribution is between 17 and 93%, and it increases from 1960 to 1990 for GB-B and GB-E. Overall, HWY is between 35 and 67%, and it increases from 1960 to present for GB-A, GB-C, and GB-F. The WB contribution is less than 35% excluding GB-A, and it increases in all five cores from 1980 to 1990.; A CMB model was also 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. Air-particulates (SRM 1648), coal-fired power plants, municipal incinerators, and pentachlorophenols (PCPs) contribute significantly to the measured concentrations of PCDD/Fs. The relative errors for {dollar}sbchisp2{dollar} equal to the number of degrees of freedom, and the multiple correlation coefficient R{dollar}sp2{dollar}, are used to determine the best fits of the calculated to the measured PCDD/F homolog profiles. 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. (Abstract shortened by UMI.)...