Evaluation of potential human health risks from exposure to volatile organic compounds in contaminated urban groundwater in the Sava river aquifer,Belgrade, Serbia

Environmental Geochemistry and Health - The oil pollutant in the Sava River aquifer in the residential area of Belgrade, Serbia was investigated in order to analyze the extent, origin and spatial...     

Land Degradation on Barren Hills: A Case Study in Northeast Vietnam

The term "barren hills" has been a keyword for land degradation in the uplands of Vietnam for over a decade. Nevertheless, the "barren" land is still not adequately ecologically characterized. In this work, we analyze land use-induced changes in vegetation and soil properties along a sequence of barren hills types formed on one physiotope. The study is undertaken in the Bac Kan province, one of the poorest upland regions where livestock plays an important role. A transition from an old-growth laurel forest to a sparse manmade grassland is characterized by a total of 177 species, rapid species turnover, and discrete dominants, and an overwhelming effect of disturbance history on both soil and vegetation patterning. Land degradation is most apparent in land use-induced maintenance of arrested successions, and the regeneration course is shifted towards drier formations. We hypothesize a conceptual model as an aid to understanding the process of early fallow differentiation in response to the patterned, fine-scale disturbances. The larger-scale implications of the observed trends in regeneration potentials deviation, and, in particular, the effect of water buffaloes in halting fallow successions, are discussed.     

Biomass waste gasification - can be the two stage process suitable for tar reduction and power generation?

A pilot scale gasification unit with novel co-current, updraft arrangement in the first stage and counter-current downdraft in the second stage was developed and exploited for studying effects of two stage gasification in comparison with one stage gasification of biomass (wood pellets) on fuel gas composition and attainable gas purity. Significant producer gas parameters (gas composition, heating value, content of tar compounds, content of inorganic gas impurities) were compared for the two stage and the one stage method of the gasification arrangement with only the upward moving bed (co-current updraft). The main novel features of the gasifier conception include grate-less reactor, upward moving bed of biomass particles (e.g. pellets) by means of a screw elevator with changeable rotational speed and gradual expanding diameter of the cylindrical reactor in the part above the upper end of the screw. The gasifier concept and arrangement are considered convenient for thermal power range 100-350 kW_th. The second stage of the gasifier served mainly for tar compounds destruction/reforming by increased temperature (around 950 °C) and for gasification reaction of the fuel gas with char. The second stage used additional combustion of the fuel gas by preheated secondary air for attaining higher temperature and faster gasification of the remaining char from the first stage. The measurements of gas composition and tar compound contents confirmed superiority of the two stage gasification system, drastic decrease of aromatic compounds with two and higher number of benzene rings by 1-2 orders. On the other hand the two stage gasification (with overall ER = 0.71) led to substantial reduction of gas heating value (LHV = 3.15 MJ/Nm³), elevation of gas volume and increase of nitrogen content in fuel gas. The increased temperature (>950 °C) at the entrance to the char bed caused also substantial decrease of ammonia content in fuel gas. The char with higher content of ash leaving the second stage presented only few mass% of the inlet biomass stream.     

Multivariate toxicity profiles and QSAR modeling of non-dioxin-like PCBs--an investigation of in vitro screening data from ultra-pure congeners

The non-dioxin-like PCBs (NDL-PCBs) found in food and human samples have a complex spectrum of adverse effects, but lack a detailed risk assessment. The toxicity profiles of 21 carefully selected PCBs (19 NDL-PCBs) were identified by in vitro screening in 17 different assays on specific endpoints related to neurotoxicity, endocrine disruption and tumor promotion. To ensure that the test results were not affected by polychlorinated dioxins, dibenzofurans or DL-PCB contaminants, the NDL-PCB congeners were thoroughly purified before testing. Principal component analysis (PCA) was used to derive general toxicity profiles from the in vitro screening data. The toxicity profiles indicated different structure-activity relationships (SAR) and distinct mechanisms of action. The analysis also indicated that the NDL-PCBs could be divided into two groups. The first group included generally smaller, ortho-substituted congeners, comprising PCB 28, 47, 51, 52, 53, 95, 100, 101, 104 and 136, with PCB 95, 101 and 136 as generally being most active. The second group comprising PCB 19, 74, 118, 122, 128, 138, 153, 170, 180 and 190 had lower biological activity in many of the assays, except for three endocrine-related assays. The most abundant congeners, PCB 138, 153, 170, 180 and 190, cluster in the second group, and thereby show similar SAR. Two quantitative structure-activity relationship (QSAR) models could be developed that added information to the SAR and could aid in risk assessments of NDL-PCBs. The QSAR models predicted a number of congeners as active and among these e.g., PCB 18, 25, 45 and 49 have been found in food or human samples.     

Concentration of heavy metals in various children's herbal tea types and their correlations

This investigation was undertaken to determine the concentrations of cadmium, lead, mercury, zinc, copper and magnesium in six tea types used as children's tea. Six types of tea of different herbal composition used for children's consumption (T1, T2, T3, T4, T5 and T6) were analyzed in three subsequent collections. The analysis of cadmium showed that the concentration was very similar in all types of children's tea, ranging from 0.233 to 0.369 mg/kg. Lead concentrations were in the range of 0.340–1.564 mg/kg without any significant differences. The analysis of mercury detected very low concentration of this metal in all samples (0.002–0.004 mg/kg). In zinc, the values ranged from 36.633 to 71.711 mg/kg, with significant differences (p < 0.001) according to tea type. Copper concentration was 10.089–30.178 mg/kg with the highest value in T4. The concentration of magnesium was significantly higher in tea T1 and T2 (102.311 and 129.422 mg/kg) in comparison with other tea types where the level was 19.811–37.411 mg/kg. The maximum tolerable limit determined by Codex Alimentarius was not exceeded in any sample. In general, correlation analysis detected high positive correlation between cadmium and lead (r = 0.89), cadmium and mercury (r = 0.92) and between lead and mercury (r = 0.77).     

Concentrations, distributions and critical level exceedance assessment of SO2, NO2 and O3 in South Africa

South Africa has been identified as a source of industrial pollution that is significant at a global scale. This study was designed to provide quantitative information, by direct measurement, across northeastern South Africa, which includes the highly industrialised Mpumalanga Highveld. The specific aim of the study was to evaluate whether or not acidic atmospheric pollution poses a threat to soils, plants and water bodies of South Africa. To address this aim, a network of 37 passive sampling sites was established to measure monthly mean concentrations of near-surface SO₂, NO₂ and ozone. The area covered extended over the northern and eastern interior of South Africa while avoiding sources of local emissions such as towns, mines and highways. The field campaign was conducted between August 2005 and September 2007. Spatial distributions and temporal trends for these pollutant gases were assessed. Critical levels analysis comparisons were made against applicable air quality standards, guidelines and limits to evaluate the potential for adverse atmospheric pollution impacts on regional environments. The assessment indicates that only in the central source area of the South African industrial Highveld are some levels exceeded. In remote areas, including the sensitive forested regions of the Drakensberg escarpment, pollutant concentrations are below the critical thresholds for environmental damage.     

Nanotechnology and groundwater remediation: A step forward in technology understanding

Nanotechnology application to contaminated site remediation, and especially the use of nanoscale zero‐valent iron particles to treat volatile organic compound (VOC)‐impacted groundwater, is now recognized as a promising solution for cost‐effective in situ treatment. Results obtained during numerous pilot tests undertaken by Golder Associates between 2003 and 2005 in North America (United States and Canada) and Europe have been used to present a synthetic cross‐comparison of technology dynamics. The importance of a comprehensive understanding of the site‐specific geological, hydrogeological, and geochemical conditions, the selection of appropriate nanoscale particles, the importance of monitoring geochemical parameters during technology application, and the potential of nanoparticle impact on microbial activity are discussed in this article. The variable technology dynamics obtained during six pilot tests (selected among numerous other tests) are then presented and discussed. © 2006 Wiley Periodicals, Inc.     

Traces of DU in samples of environmental bio-monitors (non-flowering plants, fungi) and soil from target sites of the Western Balkan region

This paper reports results of gamma and alpha spectrometric measurements for mosses, lichens, fungi and soil samples from areas in the Balkans targeted by depleted uranium (DU). Samples were collected in 2002 and 2003 in the vicinity of several villages, principally Han Pijesak (Bosnia and Herzegovina, hit by DU in 1995) and Bratoselce (South Serbia, hit by DU in 1999) and in lesser numbers from Gornja Stubla, Kosovo (which is identified as a high natural radon/thoron area) and Presevo close to the Kosovo border. In the course of gamma spectrometric measurements some results suggested samples with unusual high uranium contents which might be considered to be a signature for the presence of DU, although many samples had very high detection limits. Alpha spectrometric measurements directly proved the presence of DU for five samples, all from directly targeted places. These were samples of mosses, lichens and soil. For some samples homogeneity tests were applied which showed a rather even distribution of DU in these samples. No trace of DU was found in any sample from a dwelling.     

Aufnahme und Verteilung von Trichloressigsäure in Trieben Norwegischer Fichte

To elucidate the uptake of TCA by roots and its distribution in Norway spruce shoots, experiments with [¹⁴C]TCA were carried out in combination with radioactivity measurements after combustion, and with autoradiographic detection methods. It was shown that the uptake of TCA by spruce shoots is faster during the growth period in June than in the post-growth period in September. A high uptake of radioactivity was observed in the current-year needles, especially in the top of them, and in the corc cambium of the one-year-old wooden parts of the spruce shoots. The results of our experiments suggest uptake of TCA into spruce needles from the soil water with the transpiration stream.