Alena Ansorgová

Isomer-specific analysis of chlorinated biphenyls, naphthalenes and dibenzofurans in Delor: polychlorinated biphenyl preparations from the former Czechoslovakia.

Technical polychlorinated byphenyl (PCB) preparations--Delors 103, 104, 105, and 106--produced in the former Czechoslovakia were analyzed for their chlorobiphenyl (CB), chloronaphthalene (PCN) and chlorinated dibenzofuran (PCDF) composition and content using high resolution gas chromatography-mass spectrometry techniques. The congener patterns of Delors 103, 104, 105, and 106 resembled Aroclors 1242, 1248, 1254, and 1260. Delors contained PCNs and PCDFs, as impurities, at microgram per gram concentrations. Concentrations of PCNs and PCDFs in Delors were greater than those found in the corresponding Aroclors. The potential for the emissions of PCNs and PCDFs from Delor was estimated to be 3680 and 860 kg, respectively. Non- and mono-ortho PCBs were the major contributors to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents in Delor mixtures.

Reaction mechanism and stereochemistry of gamma-hexachlorocyclohexane dehydrochlorinase LinA.

γ-Hexachlorocyclohexane dehydrochlorinase (LinA) catalyzes the initial steps in the biotransformation of the important insecticide γ-hexachlorocyclohexane (γ-HCH) by the soil bacterium Sphingomonas paucimobilis UT26. Stereochemical analysis of the reaction products formed during conversion of γ-HCH by LinA was investigated by GC-MS, NMR, CD, and molecular modeling. The NMR spectra of 1,3,4,5,6-pentachlorocyclohexene (PCCH) produced from γ-HCH using either enzymatic dehydrochlorination or alkaline dehydrochlorination were compared and found to be identical. Both enantiomers present in the racemate of synthetic γ-PCCH were converted by LinA, each at a different rate. 1,2,4-trichlorobenzene (1,2,4-TCB) was detected as the only product of the biotransformation of biosynthetic γ-PCCH. 1,2,4-TCB and 1,2,3-TCB were identified as the dehydrochlorination products of racemic γ-PCCH. δ-PCCH was detected as the only product of dehydrochlorination of δ-HCH. LinA requires the presence of a 1,2-biaxial HCl pair on a substrate molecule. LinA enantiotopologically differentiates two 1,2-biaxial HCl pairs present on γ-HCH and gives rise to a single PCCH enantiomer 1,3(R),4(S),5(S),6(R)-PCCH. Furthermore, LinA enantiomerically differentiates 1,3(S),4(R),5(R),6(S)-PCCH and 1,3(R),4(S),5(S),6(R)-PCCH. The proposed mechanism of enzymatic biotransformation of γ-HCH to 1,2,4-TCB by LinA consists of two 1,2-anticonformationally dependent dehydrochlorinations followed by 1,4-anti dehydrochlorination.

Novel approach to monitoring of the soil biological quality

In this study, a new approach to interpretation of results of the simple microbial biomass and respiration measurements in the soil microbiology is proposed. The principle is based on eight basal and derived microbial parameters, which are standardized and then plotted into sunray plots. The output is visual presentation of one plot for each soil, which makes possible the relative comparison and evaluation of soils in the monitored set. Problems of soil microbiology, such as the lack of benchmarking and reference values, can be avoided by using the proposed method. We found that eight parameters provide enough information for evaluation of the status of the soil microorganisms and, thus, for evaluation of the soil biological quality. The usage of rare parameters (potential respiration PR, ratio of potential and basal respiration PR/BR, biomass-specific potential respiration PR/C(bio), available organic carbon C(ext), and biomass-specific available organic carbon C(ext)/C(bio)) can be recommended, besides classical and well-known parameters (microbial biomass C(bio), basal respiration BR, metabolic coefficient qCO(2)). The combination of basal parameters and derived coefficients can also extend our knowledge about the condition of the soil microorganisms. In monitoring the case studies presented, we observed that soils evaluated to possess good biological quality displayed generally higher values of organic carbon, total nitrogen, clay, and cation exchange capacity. The soils of good biological quality can display higher levels of contaminants. This is probably related with the higher content of organic carbon and clay in these soils.

Photodegradation of halobenzenes in water ice

Results from the photolysis ofo, p-dichlorobenzene, bromobenzene, andp-dibromobenzene in water ice are reported. All phototransformations appeared to be based on dehalogenation, coupling, and rearrangement reactions in ice cavities. No photosolvolysis products, i.e. products from intermolecular reactions between organic and water molecules, were found. Many of the products were very toxic substances of a high environmental risk, such as PCBs. The results support our model, in which secondary, very toxic, pollutants can be formed in ice, snow, and atmospheric ice particles from primary pollutants through the action of solar irradiation. The photoproducts may be released to the environment by ice melting and evaporation.

Photochemistry of chlorobenzene in ice

Abstract An unusual photobehaviour of chlorobenzene in ice is reported. Its photolysis at >254 nm provided very different photoproducts from those observed in liquid water where phenol derivatives are almost exclusively isolated. Thus, biphenyl and terphenyl as well as their chlorinated isomers were formed in ice, possibly via a free-radical mechanism, thanks to aggregation of the starting molecules even in very dilute solid solutions. In addition, an unusual multi-step triphenylene photoproduction is reported. Environmental aspects are also discussed.

Regional background monitoring of PBT compounds

A comparison of the modelling results of persistent, bioaccumulative and toxic (PBT) chemicals is presented with measurements. Contribution will present mean annual concentrations calculated and observed at EMEP stations and their ratios. The comparison of the calculated results with older results indicates that the model modification improved the agreement with measurement data. PBT compounds in ambient air are monitored in the area of Košetice observatory (professional observatory of the Czech Hydrometeorological Institute located in south Bohemia). Calculated and measured mean annual concentrations of PBTs in precipitation, soil, vegetation and their ratios are presented. It should be mentioned that the number of measurements in such compartments as seawater, soil and vegetation is insufficient for model verification at present. The agreement between results from MSC-East models and results from long-term regional air background monitoring in Central Europe is good.

Distribution of polycyclic aromatic hydrocarbons among different compartments of a river ecosystem

Distribution of PAHs in a river ecosystem was studied by sampling of four abiotic compartments (surface water, suspended matter, pore water and sediments) under two different hydro‐logical conditions. PAHs were detected at significant concentrations in both the solid and aqueous phase of the river ecosystem. Water concentrations were relatively low despite greater contamination of sediments. Lower MW PAHs were prevailing in the dissolved phase, higher MW PAHs in particulate materials. Concentrations of PAHs in surface waters were greater in summer than in fall. PAHs composition in the sediments was found to be relatively uniform across sites reflecting combustion generated PAH profile. Correlation and multivariate statistical analysis have shown differences between PAH patterns in solid and water samples. In aquatic samples and suspended matter, principal component analysis distinguished two separated groups of PAHs with different distribution depending on their molecular weight. In‐situ partition coefficients between the solid and aqueous phase did not differ very much between seasons. The role of organic carbon for PAHs partitioning to sediments in situ was examined. PAHs concentrations correlated to OC content only in summer. In‐situ Kocs were up to two orders of magnitude greater than tabulated Kocs based on the equilibrium partitioning model. The main reasons are the lower availibility of PAHs bound to particles from combustion sources to partition into the aqueous phase and dynamic conditions in the river ecosystem which do not enable the full equilibrium to appear.

The Spatial and Temporal Variations of Polycyclic Aromatic Hydrocarbons (PAHs) in Environmental Matrices in the Czech Republic

Abstract The paper is a review of the PAH emission inventories and the results of ambient air measurements of PAHs on regional a local level and determination of PAHs in other abiotic and biotic samples in the Czech Republic (CR). The main sources of polycyclic aromatic hydrocarbons (PAHs) in the country are associated with electric and thermal energy production, waste incineration, road traffic and some industrial processes (e. g. high-temperature coal carbonation, catalytic cracking of crude oil and aluminium production).