N-acetyl-S-(pentachlorophenyl)cysteine,a new urinary metabolite of hexachlorobenzene

The present paper describes the isolation and identification of a new metabolite of hexachlorobenzene (HCB), which is N-acetyl-S-(pentachlorophenyl)cysteine (PCC), frequently named pentachlorophenylmercapturic acid or 2-acetamido-3-(pentachlorophenylmercapto)propionic acid. PCC has been detected in and identified from rat urine. The syntheses of PCC and the isomeric tetrachlorophenylmercapturic acids (TCC) are described in the following paper.     

EPA's selenium revision heads into murky waters

As the US EPA revises its standards for selenium in fresh water, a heated debate rages between government scientists, who say that existing standards must be tightened because selenium contamination is widespread, and industry scientists who believe that it is an environmental oddity. Fish, crustaceans and birds appear to be uniquely sensitive to even modest increases in environmental concentrations of this element. To set new standards, EPA must find a way to take into account an emerging understanding of selenium's complex geochemistry.     

Preparations and properties of transformation products of pentachlorophenol (PCP)

The present paper describes preparations and properties of pentachlorophenol derivatives.     

Scrubbing intensification for sulphur and ammonia compounds removal

Operating conditions were optimised in a new compact scrubber in order to remove odorous sulphur (H(2)S and CH(3)SH) and ammonia compounds. The influence of the superficial gas and liquid velocities, pH, contactor length, inlet concentrations (sulphur compounds, ammonia, chlorine), and the mixing effects was characterised. Whereas abatement increased with velocities, pH and the chlorine concentration, an increase of inlet CH(3)SH concentration drove to a worse efficiency of process. Moreover, the contactor length and the presence of another pollutant in the gas phase only played a role on the methylmercaptan removal. Finally, the reactive consumptions were estimated at the outlet of the reactor. The chlorination by-product quantification permitted to understand the under-stoichiometry.     

Polychlorierte Dibenzo-p-dioxine und Dibenzofurane (PCDD/F)

Distillation residues of dry cleaning machines contain small quantities of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F), independent of the type of solvent employed. PCDD/F were not only detectable in distillation residues using perchloroethylene as dry cleaning solvent, but also similar quantities and congeneric patterns of PCDD/F were found in residues from machines operated with stoddart solvent or CFC 113. Current results suggest that PCDD/F occurrence is linked to the dirt adhering to the textiles. Dirty textiles were a prerequisite for finding PCDD/F in the distillation residues. The congeneric patterns of the identified PCDD/F in the distillation residues were found to be similar as those from household dust, sewage sludge, as well as those from soil, sediments, and street dust. The investigations clearly show that perchloroethylene is not linked to PCDD/F formation. The freshly produced, commercial perchloroethylene as well as laboratory-distilled perchloroethylene did not contain any detectable quantities of PCDD/F. Also, the possibility of PCDD/F formation through decomposition reactions of the solvents during the dry cleaning process can be excluded on the basis of existing data.     

Dynamisiertes Emissionskataster für den Freistaat Sachsen

A computer aided tool was created for the calculation of emission values in Saxony. It is based on the Geographic Information System ArcInfo and enables the emission values for past, present and future periods to be assessed. At present, the anthropogenic air pollutants SO₂, NO_x, CO, NH₃, NMVOC, TSP, CO₂, CH₄ and N₂O can be calculated by means of emission factors and statistical values. The tool is open to future expansions. The moduls represent the following emission groups: Power stations, large agricultural farms and large industrial plants as point sources, as well as transport, households, small consumer and the total emission of agriculture as area sources. The local resolution of emission values, the relationship of emission values to geographic or political territories, the inclusion of a high resolved digital street network, and the use of actual data concerning land use, density of population and density of build up areas are realized by GIS ArcInfo. The dynamic emission inventory can be used, alone or in conjunction with an atmospheric dispersion model, to assess trends in air quality.