A prospective cytogenetic study of third-trimester placentae in small-for-date but otherwise normal newborns

Data in the literature suggest that confined placental mosaicism might be associated with intrauterine growth retardation. However, this association may be coincidental and due to bias of ascertainment. We therefore started a prospective study based on the cytogenetic evaluation of placentae derived from growth-retarded newborns. We further minimized possible bias by excluding those small-for-date infants displaying findings which already could explain intrauterine growth retardation (mothers who are smokers, multiple pregnancies, gestosis, dysmorphic infants). In a collection of 71 small-for-gestational age newborns, we did not see a single case of true confined placental mosaicism.     

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.     

Landfill aeration within the scope of post-closure care and its completion

The time frame required for post-closure care of Municipal Solid Waste (MSW) landfills is often assessed over several decades or centuries. One possibility to significantly shorten this period and, at the same time, improve the emission behavior exists with in situ aeration. Positive effects in connection with this method for biological stabilization have been investigated and published elsewhere. However, until today neither generally accepted monitoring guidelines nor completion criteria have been defined. With the paper on hand the authors propose a methodology for the assessment of both, total and remaining stabilization periods for aerated landfills. The central component of this methodology is a carbon balance. The latter is based on a detailed waste characterization in combination with online monitoring of the emissions (gas and leachate). The methodology is exemplarily demonstrated by means of data derived from a full scale project in Northern Germany. Here it could be shown that the predicted aeration period of approximately 6.4 years was sufficient to bio-stabilize the landfill.Furthermore, proposals for the completion of landfill aeration are presented. In this connection, carbon balance is of particular importance since the amount of biodegradable organic carbon mainly determines the emission potential. Additional parameters, aiming at a validation of the state of biological stabilization achieved during aeration are proposed and described.     

Shoot growth of mature Fagus sylvatica and Picea abies in relation to ozone

Epidemiological analysis of sequential growth data may be a tool in assessing ozone sensitivity of mature trees. Annual shoot growth of mature Fagus sylvatica in 83 Swiss permanent forest observation plots and of Picea abies in 61 plots was evaluated for 11 and 8 consecutive years, respectively, using branches harvested every 4 years. The data were assessed as annual deviation from average growth and related to fructification, ozone, meteorological parameters, and modelled soil water content using a mixed linear model. In beech, a significant association between ozone and shoot growth was observed which corresponded to a 7.4% growth reduction between 0 and 10 ppm h AOT40 (accumulated ozone over threshold 40). This is in the same order of magnitude as the response observed in experiments with seedlings. No interaction was found between ozone and drought parameters. In Norway spruce, shoot growth was neither associated with ozone nor with drought.     

Risk assessments for forest trees: the performance of the ozone flux versus the AOT concepts

Published ozone exposure-response relationships from experimental studies with young trees performed at different sites across Europe were re-analysed in order to test the performance of ozone exposure indices based on AOTX (Accumulated exposure Over a Threshold of X nmol mol(-1)) and AF(st)Y (Accumulated Stomatal Flux above a threshold of Y nmol m(-2) s(-1)). AF(st)1.6 was superior, as compared to AOT40, for explaining biomass reductions, when ozone sensitive species with differing leaf morphology were included in the analysis, while this was not the case for less sensitive species. A re-analysis of data with young black cherry trees, subject to different irrigation regimes, indicated that leaf visible injuries were more strongly related to the estimated stomatal ozone uptake, as compared to the ozone concentration in the air. Experimental data with different clones of silver birch indicated that leaf thickness was also an important factor influencing the development of ozone induced leaf visible injury.     

Cu and Zn mobilization in soil columns percolated by different irrigation solutions

We investigated the effects of different concentrations of nitrate and ammonium in irrigation water on the mobilization of Zn and Cu in repacked soil columns with a metal-polluted topsoil and unpolluted subsoils over two and a half years. Soil solution samples were collected by suction cups installed at vertical distances of a few centimeters and analyzed for dissolved organic carbon (DOC), Cu, and Zn (total and labile). During high N treatments the pH decreased and the presence of exchangeable cations resulted in Zn mobilization from the surface soil. The nitrogen input stimulated the biological activity, which affected both concentration and characteristics of DOC and consequently Cu speciation. Metal leaching through the boundary between the polluted topsoil and the unpolluted subsoils increased soil-bound and dissolved metals within the uppermost 2 cm in the subsoils. Our study shows that agricultural activities involving nitrogen fertilization can have a strong influence on metal leaching and speciation.     

Assessment of heavy metal releases from the use phase of road transport in Europe

An emission inventory was compiled for heavy metal air emissions from road transport in Europe (EU-40). For the database, country-specific data was taken such as the diesel and gasoline fuel consumption per country, the content of Pb in gasoline and diesel fuel and the share of different vehicle types. For tyre and brake wear emissions, average wear rates and heavy metal contents of different materials were used to develop emission factors for tyre and brake wear. It covers exhaust emissions (Pb from gasoline and diesel) as well as non-exhaust emissions (As, Cd, Cr, Ni and Pb from the wear of brake linings and vehicle tyres). The base year is 2000, and two scenarios were developed for 2010, a business as usual (BAU) scenario and a maximum feasible technical reduction (MFTR) scenario. Both result in a remarkable decrease in Pb exhaust emissions and a rising share of non-exhaust emissions. To assess the results, the inventory is (a) compared to an inventory compiled with a top-down approach that covers the same area and years but only emissions from combustion processes and (b) added to an inventory covering all sectors for heavy metal air emissions.     

On-road and laboratory investigation of low-level PM emissions of a modern diesel particulate filter equipped diesel passenger car

Modern diesel particulate filter (DPF) systems are very effective in reducing particle emissions from diesel vehicles. In this work low-level particulate matter (PM) emissions from a DPF equipped EURO-4 diesel vehicle were studied in the emission test laboratory as well as during real-world chasing on a high-speed test track. Size and time resolved data obtained from an engine exhaust particle sizer (EEPS) and a condensation particle counter (CPC) are presented for both loaded and unloaded DPF condition. The corresponding time and size resolved emission factors were calculated for acceleration, deceleration, steady state driving and during DPF regeneration, and are compared with each other. In addition, the DPF efficiency of the tested vehicle was evaluated during the New European Driving Cycle (NEDC) by real time pre-/post-DPF measurements and was found to be 99.5% with respect to PM number concentration and 99.3% for PM mass, respectively. PM concentrations, which were measured at a distance of about 10 m behind the test car, ranged from 1 to 1.5 times background level when the vehicle was driven on the test track under normal acceleration conditions or at constant speeds below 100 kmh^?1. Only during higher speeds and full load accelerations concentrations above 3 times background level could be observed. The corresponding tests in the emission laboratory confirmed these results. During DPF regeneration the total PM number emission of nucleation mode particles was 3–4 orders of magnitude higher compared to those emitted at the same speed without regeneration, while the level of the accumulation mode particles remained about the same. The majority of the particles emitted during DPF regeneration was found to be volatile, and is suggested to originate from accumulated sulfur compounds.     

Metal fractionation in a contaminated soil after reforestation: Temporal changes versus spatial variability

In a lysimeter experiment, topsoils were polluted with filter dust from a non-ferrous metal smelter and then planted with trees. Sequential extractions were used to follow the changes in metal fractionation of Cu, Zn, Cd, and Pb over 42 months. Plant-free and uncontaminated soils served as reference. In the contaminated and planted soils, the largest changes in speciation occurred within the first 6 months. The relative amounts of certain metal fractions were linearly related to each other, indicating systematic redistribution between fractions. The results indicate that under natural conditions with high heterogeneity in total metal contents spatial differences are more important than temporal variations in determining the fractionation and solubility of metals in contaminated soils. In the absence of plants soils exhibited a completely different fractionation 30 months after pollution, with much higher proportions in the more refractory phases. This suggests that plant activity kept the metals in a more soluble form.     

Suitability of using diffusive gradients in thin films (DGT) to study metal bioavailability in mine tailings: possibilities and constraints

Background, aim, and scope  

Diffusive gradients in thin films (DGT) have been recognized as a suitable tool to assess in situ metal bioavailability in soils. Mine tailings have some singular characteristics such as high heavy-metal concentrations, low pH, or absence of water retention capacity that may compromise the correct application of this technique whose applicability is known to be pH dependent. The goal of this study was to determine the response of DGT devices in heavy-metal-polluted mine tailings with different pH. In addition some experiments were performed in order to determine the effect of acidic pH and dissolved ions on the binding properties of the chelating resin.