Long lasting nitrate leaching after bark beetle attack in the highlands of the Bavarian Forest National Park

During the past decade bark beetle (Ips typographus) attacks killed nearly all of the Norway spruce [Picea abies (L.) Karst.] stands in the unmanaged zone in the highlands of the Bavarian Forest National Park. This study was conducted to predict if and how long the catastrophic event might cause elevated nitrate NO3(-) concentration in seepage water, and if the presence of ground vegetation may reduce NO3(-) leaching. A chronosequence approach was used to investigate NO3(-) leaching before and after the death of trees. Additionally, the impact of ground vegetation coverage on NO3(-) leaching was determined. Flux weighted yearly NO3(-) concentrations were significantly elevated in the first 5 yr after the dieback compared with intact stands (27 micromol(c) L(-1)), with highest concentrations in the fifth year after the dieback (579 micromol(c) L(-1)). Lowest NO3(-) concentrations were observed 17 yr after the dieback (10 micromol(c) L(-1)). Suction cups in places without ground vegetation showed significantly higher NO3(-) concentrations of 163 to 727 micromol(c) L(-1) (Year 2-5 after the dieback) than suction cups without vegetation. However, net uptake of N by ground vegetation observed during the first 7 yr after the dieback was low on a plot scale. Compared with other severe disturbances in forests, NO3(-) concentrations were elevated for a longer period. Due to high rates of precipitation, NO3(-) dilution occurred and concentrations remained mostly below the European critical level for drinking water. Part of the observed heterogeneity in NO3(-) concentrations could be attributed to different patterns of ground vegetation coverage.     

Do heavy metals and metalloids influence the detoxification of organic xenobiotics in plants?

Background, aim and scope  

Mixed pollution with trace elements and organic industrial compounds is characteristic for many spill areas and dumping sites. The danger for the environment and human health from such sites is large, and sustainable remediation strategies are urgently needed. Phytoremediation seems to be a cheap and environmentally sound option for the removal of unwanted compounds, and the hyperaccumulation of trace elements and toxic metals is seemingly independent from the metabolism of organic xenobiotics. However, stress reactions, ROS formation and depletion of antioxidants will also cause alterations in xenobiotic detoxification. Here, we investigate the capability of plants to detoxify chlorophenols via glutathione conjugation in a mixed pollution situation.     

Identification of marine organisms using kinetic and spectral properties of their bioluminescence

We have used a polychromator consisting of six photomultiplier tubes, each filtered to a different wavelength with narrow band-pass interference-filters, to study bioluminescence. Spectral and kinetic data collected from ten marine species in the laboratory describe their luminous flashes. These data suggest that the concept of luminous signatures, within the limits of our studies, is a valid one, with potential uses for future biological studies both in the laboratory and in situ. The kinetic parameters considered were rise time (RT), decay time (DT) and total time (TT), while the spectral parameters consisted of ratios of light intensities at 480 and 520 nm to the intensity at 500nm. Oneway analysis of variance (ANOVA) demonstrated significant heterogeneity among species for all variables. A posteriori analysis performed with the ANOVA for TT indicated that mean TT for most species is significantly different from all other species. Canonical discriminant analysis was performed to estimate the value of kinetic and spectral parameters for species' identification. Kinetic data were somewhat more valuable in species' classification than spectral data. Discriminant analysis with RT and DT alone gave 83.1% correct species-classifications. Classification success based only on relative intensities at 480 and 520 nm was 77.5%. When all four variables were included, classification success was 100%.     

Evaluation of pollution-related stress factors for forest ecosystems in central Europe

Since the early eighties air pollution by SO2 and Pb and, to a lesser degree by NOx and NH3, have been significantly reduced in Europe. This was done in part for the protection of forest ecosystems. The reductions are reflected in the pollutant impacts and inputs and have been verified through the bioindicator Norway spruce. In contrast, ozone concentrations increased at most of the evaluated measuring locations and trends were calculated based on the results of about 100 stations in Austria and Germany. Despite reduced emissions, large parts of the forest ecosystems are still affected by air-pollution impacts. Negative effects can be assessed using different legal standards and Critical Levels and Critical Loads, respectively: The legal standard for the evaluation of SO2 impact, as used in Austria, is well suited. The provisional European Critical Level for ozone, the AOT40 must, in order to be a meaningful criterion for field applications, be further refined. Continuing the Critical Load concept, the spatial risk of acid depositions in areas of high geomorphic variability were evaluated using the new parameter of 'critical soil depth'. With the help of the newly defined 'lead accumulation index', the accumulation of Pb from air pollution could be evaluated. Air-pollution inputs and the spatial acidification risk is directly related to altitude. Up to altitudes of 1000 m and 1100 m, SO2 impact and acid depositions, respectively were indicated and elevated ozone doses and Pb inputs were observed in the sensitive sub-alpine areas. These results underline the necessity for increased protection of mountain forest ecosystems, among others through a further reduction of emissions or forest-related strategies.     

Sensitivity analysis and evaluation of microFacCO: a microscale motor vehicle emission factor model for CO emissions

This paper presents a sensitivity analysis of a microscale emission factor model (MicroFacCO) for predicting real-time site-specific motor vehicle CO emissions to input variables, as well as a limited field study evaluation of the model. The sensitivity analysis has shown that MicroFacCO emission estimates are very sensitive to vehicle fleet composition, speed, and ambient temperature. For the present U.S. traffic fleet, the CO emission rate (g/mi) is increased by more than 500% at 5 mph in comparison with a speed greater than 40 mph and by approximately 67% at ambient temperatures of 45 degrees F and > or = 95 degrees F in comparison with an ambient temperature of 75 degrees F. The input variable "emission failure standard rate" is more sensitive to estimating emission rates in the 1990s than in the 2000s. The estimation of emission rates is not very sensitive to relative humidity. MicroFacCO can also be applied to examine the contribution of emission rates per vehicle class and model year. The model evaluation is presented for tunnel studies at five locations. In general, this evaluation study found good agreement between the measured and the modeled emissions. These analyses and evaluations have identified the need for additional studies to update the high-speed (>35 mph) air conditioning (A/C) correction factor and to add effects due to road grades. MicroFacCO emission estimates are very sensitive to the emission standard failure rate. Therefore, the model performance can be greatly improved by using a local emission standard failure rate.     

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The Role of Organic Matter in Natural Aquatic Systems: Analytical Constraints

The dissolved organic matter in aquatic systems consists of a heterogeneous mixture of compounds with wide ranging chemical properties and diverse origins. the presence of organic matter (OM) in surface and ground waters has important implications with regard to the mobility and therefore fate of many potential organic and inorganic pollutants. the majority of the analytical approaches in current use require exhaustive pre-treatment steps which may lead to the formation of artefacts within the sample. an analytical technique based upon gel permeation chromatography is proposed as a more reliable procedure for the characterisation of naturally occurring dissolved organic matter.