Despite the recent efforts to investigate the distribution and fate of persistent organic pollutants in the tropical and subtropical regions of Asia, very little was known about the temporal change of polychlorinated biphenyls (PCBs) in the environmental ecosystem of China. In this study, three dated sediment cores collected from the Pearl River Delta of southern China were analyzed for a large suite of PCB congeners, from which the temporal profiles of PCB abundances, fluxes, and homologue patterns were constructe...
Test runs in the TAMARA test facility to investigate the influence of decreasing lower heating value on the combustion of waste showed that the combustion quality could easily be kept constant at heating values exceeding 5 MJ/kg. The burnout of grate ashes and flue gas had slightly fallen off at lower heating values whereas the level of PCDD/F in the raw gas stayed constant in all tests. The volatility of elements was correlated with the fuel bed temperature. The leaching of heavy metals out of the bottom ashes...
1.1 Scope and Objectives
A small number of viable options are presently available for the bleaching of wood pulp (delignification and brightening) during the manufacture of pulp and paper. The use of chlorine dioxide (ClO2) in the bleaching process has largely superceded the earlier use of Cl2, or elemental chlorine, in the majority of North American pulp mills: It was discovered over a decade ago that the previous widespread use of Cl2 contributed to the production and subsequent release to the environment of...
Abstract
A bleached sulfate integrated pulp and paper mill producing printing and writing paper from mixed tropical hardwood and bamboo was studied. The mill uses a `conventional bleaching sequence`, C-E-H1-H2, with an average chlorine consumption of 80 kg per ton of air-dried pulp (ADP). The content of polychlorinated dibenzofurans (PCDFs) and dibenzo-p-dioxins (PCDDs) in the bleaching filtrate in term of the Nordic Toxicity EQuivalent (N-TEQ) was 33.5, 1.15, 0.56 and 0.014 pg/L for the E-, C-, H1- and H2-...
Introduction
There is considerable public, scientific and regulatory concern over the possible adverse health effects of chronic exposure to trace levels of persistent organic pollutants. The class of compounds made up of the polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF), often collectively known as dioxins, has received widespread attention and attracted a great deal of research, following the accidental release of the most toxic of these (2,3,7,8 TCDD) at Seveso in 1976.
Diox...
` Comparative risk assessment provides a systematic way to compare environmental problems that pose different types and degrees of health risk. It combines information on the inherent hazards of pollutants, exposure levels and population characteristics to predict the resulting health effects. Using data from available sources, rapid, inexpensive comparative risk assessments can identify the most significant health problems. Together with consideration of costs, technical feasibility and other factors, the...
Abstract This paper presents data on the source of PCDDs/PCDFs in cement plant stack emissions, demonstrating that these emissions are not necessarily all created by the process. The data potentially demonstrates that some of the PCDDs/PCDFs in the emissions are pre-existing dioxins and furans that are vaporized out of the kiln raw feed. This calls into question the assumption that PCDD/PCDF emissions can be decreased below a certain point. The EPA has acknowledged resuspended PCDD/PCDF emissions, such as from...
The U.S. Department of Energy`s (DOE`s) Environmental Restoration Program directs the assessment and cleanup of inactive sites and surplus facilities contaminated from previous defense and non-defense-related programs. All cleanup activities must comply with federal, state, Indian Nation, and local laws and regulations. In completing environmental restoration activities, DOE is committed to working with stakeholders to understand technical issues and evaluate alternatives. Two important program goals include...
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