It is shown for the first time that the volatile highly chlorinated C2 hydrocarbons (VCHCs) trichloroethene (TRI; C2HCl3), tetrachloroethene (PER; C2Cl4) and methyl chloroform (MC; C2H3Cl3), but also C1 hydrocarbons tetrachloromethane and chloroform can be naturally formed in the sediment of salt lakes (ssl). Archaic halobacteria appear to play a key role in the microbial formation involved. TRI, PER and MC can be transformed into trichloroacetic acid (TCA) in the atmosphere. TRI and PER can also be metabolised into TCA following uptake by plants. Already considerably phytotoxic by itself, TCA's phytotoxicity is exacerbated if the vegetation concerned is simultaneously exposed to drought‐stress. TRI and PER, emitted by these newly identified natural sources, can accelerate desertification in semi‐arid and arid climate zones in consequence of the destabilisation of vegetation by its phytotoxic metabolite TCA.

Systematic investigations were performed to study the dependence of the extraction efficiency of persistent organic pollutants (POPs), including chlorobenzenes, HCH isomers, DDX, PCB congeners, and PAHs, on the accelerated solvent extraction (ASE) operating variables solvent and temperature. Mixed soil samples from two locations with considerable differences in soil properties and contamination in the Leipzig-Halle region (Germany) were used. The objective was to optimize ASE for the extraction of POPs from real soil samples and to improve on the results achieved with Soxhlet extraction (SOX). Solvents with differing polarities were tested. Quadruple and triple determinations were performed on the two soils, respectively, between 20 and 180 degrees C in 20 degrees C steps. All the results were compared with those obtained by SOX, as well as, in some cases during preliminary studies, by ultrasonic extraction (USE). In ASE, the optimum conditions proved to be two extraction steps at 80 and 140 degrees C (average RSD 10.7%) with three static cycles (extraction time 35 min) using toluene as solvent and at a pressure of 15 MPa. Owing to the superior analyte/matrix separation by ASE, in many cases for real soil samples analytical values better by up to 1 order of magnitude or even more were obtained compared to SOX results.

Accelerated solvent extraction (ASE) was used for the simultaneous extraction of semivolatile organic compounds (SOCs) including chlorobenzenes (1,2,3,4-tetra-, penta-, hexachlorobenzene), HCH isomers (r-, -, γ-, δ-, E-HCH), DDX (p,p′-DDT, -DDE, -DDD), PCB congeners (28, 52, 101, 138, 153, 180), and PAHs (phenanthrene, anthracene, fluoranthene, pyrene, benzo[a]pyrene) from mosses (Pleurozium schreberi) growing in regional locations (central Germany) and pine needles (Pinus sylvestris L.) from southern Russia (near the Caspian Sea). The results were compared with those obtained by ultrasonic extraction (USE). Using mixed moss samples (thorough cleanup, only minor interference during GC/ MSD analysis) from one location mainly served to optimize two parameters, extraction solvent and temperature. The most favorable extraction conditions proved to be nhexane as the extraction solvent, two temperature stages of 40 and 120°C, a pressure of 15 MPa, and three static cycles in each case. These conditions were then applied to the extraction of SOCs from the wax and the inner pine needle fraction, which beforehand had undergone extractive separation with dichloromethane. ASE was found to be especially advantageous in the case of higher multiple exposures to pollutants and the resultant complicated matrixes (oleiferous extracts, pollutant/matrix conjugates). Owing to the much better separation of analyte/ matrix, in many cases increases of 1-2 orders of magnitude were obtained in the analytical values of the contaminated sample materials compared to those obtained with USE.Over 130 anthropogenic organic substances which can have biological effects have been detected in European forestlands. Moreover, there is also an abundance of other organic substances accumulating in biomonitoring objects such as mosses and pine needles. These chemicals can significantly contribute to the multiple pollution of a location. The complicated plant matrix with large fractions of structures abundant in lipids, its diversity among different and even the same plant species from one location to another, and the effects of these and numerous other factors 1 make the extraction, cleanup, and analysis of lipophilic semivolatile organic compounds (SOCs) 2 a highly challenging process. Analytical difficulties in the analysis of pine needles in particular are due to multiple exposures to pollutants, depending on specific locations. Methodological improvements are making it possible to better understand the processes by which anthropogenic pollutants such as SOCs can penetrate and accumulate in plants, as well as the way in which they can also cause damage in the inner plant compartments. 3 In view of the known carcinogenic 4 and teratogenic 5 effects, as well as the endocrinic effects 6,7 recently mooted in particular for organochlorines, an improved quantitative determination of persistent organochlorines and polycyclic aromatic hydrocarbons (PAHs) in biological compartments is essential if the hazards of these compounds are to be better assessed.Over ...

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