Integrated evaluation of the performance of a more than seven year old permeable reactive barrier at a site contaminated with chlorinated aliphatic hydrocarbons (CAHs)

An important issue of concern for permeable reactive iron barriers is the long-term efficiency of the barriers due to the long operational periods required. Mineral precipitation resulting from the anaerobic corrosion of the iron filings and bacteria present in the barrier may play an important role in the long-term performance. An integrated study was performed on the Vapokon permeable reactive barrier (PRB) in Denmark by groundwater and iron core sample characterization. The detailed field groundwater sampling carried out from more than 75 well screens up and downstream the barrier showed a very efficient removal (>99%) for the most important CAHs (PCE, TCE and 1,1,1-TCA). However, significant formation of cis-DCE within the PRB resulted in an overall insufficient efficiency for cis-DCE removal. The detailed analysis of the upstream groundwater revealed a very heterogeneous spatial distribution of contaminant loading into the PRB, which resulted in that only about a quarter of the barrier system is treating significant loads of CAHs. Laboratory batch experiments using contaminated groundwater from the site and iron material from the core samples revealed that the aged iron material performed equally well as virgin granular iron of the same type based on determined degradation rates despite that parts of the cored iron material were covered by mineral precipitates (especially iron sulfides, carbonate green rust and aragonite). The PCR analysis performed on the iron core samples indicated the presence of a microbial consortium in the barrier. A wide range of species were identified including sulfate and iron reducing bacteria, together with Dehalococcoides and Desulfuromonas species indicating microbial reductive dehalogenation potential. The microbes had a profound effect on the performance of the barrier, as indicated by significant degradation of dichloromethane (which is typically unaffected by zero valent iron) within the barrier.     

Renatal diagnosis of mosaic tetrasomy 12p/trisomy 12p by fluorescent in situ hybridization in amniotic fluid cells: A case report of pallister–killian syndrome

A prenatally detected case of a rare mosaic tetrasomy 12p/trisomy 12p is reported, presenting as the well-known accessory isochromosome 12p and a supernumerary single 12p marker in 17/24 and 6/24 clones of cultured amniotic fluid cells, respectively. The chromosomal nature of both marker chromosomes was investigated in cultured amniotic fluid cells by fluorescent in situ hybridization with various probes: the 12-centromeric probes pa12H8 and D12Z3, a whole chromosome 12 paint, and the chromosome 12p-specific paint M28. DNA analysis revealed a maternal origin of the extra 12p material. After counselling, the parents requested termination of pregnancy. Inspection and autopsy of the fetus revealed many of the dysmorphisms and internal structural abnormalities of the Pallister–Killian syndrome.     

Book Reviews

ION‐SELECTIVE ELECTRODES IN ANALYTICAL CHEMISTRY, Vol. 2 by H. Freiser (ed.), Plenum Press, New York, 1980.

CARCINOGENESIS AND MUTAGENESIS by Myron A. Mehlman, Morris F. Cranmer and Raymond E. Shapiro, from the Journal of Environmental Pathology and Toxicology (Official Organ of the American College of Toxicology), 388 pages and 135 tables and figures, 1977, linen, format 261 × 178 mm, ISBN 0–930376–02–1, printed by Pathotox Publishers, Inc., Park Forest South, Illinois 60466, $23.00.     

Multicriteria Analysis of the Conflicts between Rural Development Scenarios in the Gordon District,Scotland

In this paper a methodology is presented allowing the evaluation of possible development scenarios for a region against a set of environmental and other criteria on the basis of the assessment of the scenarios by local experts. The methodology starts with the pairwise comparison of the scenarios by different panels of local actors and decision makers. This information is aggregated using multicriteria analysis in order to arrive at a ranking of the scenarios or to analyse the trade-offs between different groups of criteria. The methodology is explained and illustrated with an example for the Gordon District in Scotland.     

A stress-strain model to evaluate the forest situation in Germany and the state of the art of damage research

The situation and the latest findings of forest damage research in Germany are discussed. A newly developed concept for this research is described. This concept allows to identify the drawbacks of the recent damage research concept but also the integration of results compiled up to now. The importance for including natural occurring stress factors such as climate, soil conditions or local situation of individual species is outlined.     

Evaluating microbial purification during soil treatment of wastewater with multicomponent tracer and surrogate tests

Soil treatment of wastewater has the potential to achieve high purification efficiency, yet the understanding and predictability of purification with respect to removal of viruses and other pathogens is limited. Research has been completed to quantify the removal of virus and bacteria through the use of microbial surrogates and conservative tracers during controlled experiments with three-dimensional pilot-scale soil treatment systems in the laboratory and during the testing of full-scale systems under field conditions. The surrogates and tracers employed included two viruses (MS-2 and PRD-1 bacteriophages), one bacterium (ice-nucleating active Pseudomonas), and one conservative tracer (bromide ion). Efforts have also been made to determine the relationship between viruses and fecal coliform bacteria in soil samples below the wastewater infiltrative surface, and the correlation between Escherichia coli concentrations measured in percolating soil solution as compared with those estimated from analyses of soil solids. The results suggest episodic breakthrough of virus and bacteria during soil treatment of wastewater and a 2 to 3 log (99-99.9%) removal of virus and near complete removal of fecal coliform bacteria during unsaturated flow through 60 to 90 cm of sandy medium. Results also suggest that the fate of fecal coliform bacteria may be indicative of that of viruses in soil media near the infiltrative surface receiving wastewater effluent. Concentrations of fecal coliform in percolating soil solution may be conservatively estimated from analysis of extracted soil solids.     

Persistent organochlorine pollutants in human serum of 50-65 years old women in the Flanders Environmental and Health Study (FLEHS). Part 2: Correlations among PCBs,PCDD/PCDFs and the use of predictive markers

In 1999, the FLEHS was set by the Flemish Ministry of Health, Belgium to assess pollutant concentrations and related health effect biomarkers in humans living in Flanders. Concentrations of selected organochlorine pesticides, polychlorinated biphenyls (PCB) and polychlorinated dibenzo-p-dioxins (PCDD) and furans (PCDF) were measured by gas chromatography-mass spectrometry and Chemical-Activated LUciferase gene eXpression (CALUX) bioassay in 47 serum pools of 200 women between 50 and 65 years living in two areas of Flanders. Correlation between TEQ values of different groups of compounds were computed in these pool results and it was found that total toxic equivalencies (TEQs) correlated well with the values of the groups of contributing compounds: mono-ortho PCBs (r = 0.77), non-ortho PCBs (r = 0.65) and PCDD/Fs (r = 0.88). The total TEQ was lower correlated to the CALUX-TEQ (r = 0.57). When calculating associations between those classes of compounds in the two studied regions separately, they were all higher correlated in the urban area compared to the more rural region. High correlation coefficients (r > 0.80) were also calculated between individual compounds and groups of compounds. It was suggested that in this studied background-exposed population, some compounds could be good predictors for a group: e.g. PCB 153 for indicator and total PCBs, PCB 118 for total PCB TEQ, PCB 156 for mono-ortho PCB-TEQs and total TEQ, 2,3,4,7,8-P5CDF for PCDD/F TEQs and total TEQs. This means that in pooled serum samples correlations between persistent organochlorine compounds are as strong as for individual POP measurements observed in earlier studies.     

Effects of atmospheric ammonia on vegetation--a review

Atmospheric ammonia does not only cause acute injuries at vegetation close to the source, but significantly contributes to large scale nitrogen eutrophication and acidification of ecosystems because the amount of sources is high and after conversion to ammonium it can reach remote areas by long-range atmospheric transport. Besides having acute toxic potential, NH(3) and NH(4)(+) (= NH(y)) may disturb vegetation by secondary metabolic changes due to increased NH(y) uptake and assimilation leading to higher susceptibility to abiotic (drought, frost) and biotic (pests) stress. Prevention of damage to natural and semi-natural ecosystems will only be achieved if NH(3) emissions are drastically reduced. In this paper, the current knowledge on NH(y) emission, deposition, and its effects on vegetation and ecosystems are reviewed. Critical levels and critical loads for nitrogen deposition are discussed.