Critical Loads Exceedances in Germany and their Dependence on the Scale of Input Data

Critical load exceedances have been used as an effects-related parameter for guiding international air emission control negotiations. High-resolution critical load data are combined with low-resolution deposition data.This article shows that doing so systematicallyunderestimates `true' critical load exceedances as obtainedfrom combining critical load and deposition data of identicalhigh spatial resolution. 95th percentile critical loadexceedances in EMEP grids based on high resolution depositiondata are 60 and 150% higher (mean values for nutrientnitrogen and acidity, respectively) than critical loadexceedances based on the low resolution EMEP depositionmodel. The latter are used in international negotiations. Differences in individual EMEP grid squares vary betweeninsignificantly different from zero and 340%, depending onregional deposition and critical load characteristics andcritical load types (nutrient nitrogen versus acidity).Exceedances based on high-resolution deposition values arealso compared to EMEP grid averages of these values forforests only. This comparison excludes the effect ofsystematically higher depositions to forests. Still, thescale difference of (averaged, low-resolution) deposition and(high-resolution) critical loads data yields underestimatesof the 95th percentiles by on average ca. 20%.These systematic errors due to the scale dependence should beborne in mind when interpreting effects of internationalemission control measures.     

Methane in the Atmosphere

Methane is present in the troposphere with a volume concentration of about 1.5 ppm. Estimates of Koyama (1963) indicate a predominantly biological origin with a total production rate of about 2.7 × 10¹⁴ g CH₄/yr. From that he estimated the atmospheric lifetime of methane to be around 20 years. Measurements of the C-l4 in methane by Libby and later by Bainbridge, et al. (1961 ) gave a C-l4 content of 75% of recent wood and, therefore, confirm the predominant biological origin, the addition of inactive CH; from industrial sources being only about 25%. Much less is known about sinks of CH₄. Cadle (1966) reported fairly high destruction rates by atomic O, a reaction which should be important at high altitude. Bainbridge (1966) indeed reports a decrease in the measured methane concentration above the tropopause. He, however, considers this decrease too small to account for the destruction rate of 20 years estimated by Koyama. Our measurements on air samples collected on aircraft flights at various altitudes show a high variability of the CH₄ content both with time and altitude.     

Beurteilung von Gefahren aus militärischen Altlasten in Einzugsgebieten von Trinkwassergewinnungsanlagen auf der Basis eines Kriterienkataloges

To include consequences emanating from former military sites on the drinking water supply, a catalog of criteria has been developed which permits the determination and assessment of the hazards in general and their impact on human health in particular. The assessment criteria correspond to the special requirements and standards for drinking water hygiene and protection in Germany. The criterion catalog is a completion module to the usual praxis and existing conceptions, and has proved its practical value in the initial assessment of military sites in the new federal states of Germany. The scheme is a control instrument suitable for obtaining an assessment concerning the extent to which drinking-water resources are and will be affected by former waste disposal and other contaminated sites at the present and in the future.     

Raumbezug und Repräsentativität in der Ökologischen Flächenstichprobe

The quality of regionalizations can only be evaluated with regard to its specific purposes. In environmental monitoring, regionalizations, besides being an analysis tool, has a great importance on the selection of monitoring sites. The article describes the relationship between regionalization, selection procedure and representativeness using the example of Ecological Area Sampling (EAS) and presents the regionalization which was tested in an EAS pilot study.     

Ant species composition and richness in different types of semi-natural grasslands

The distribution of ant species was studied across different types of semi-natural grasslands in a mosaic landscape in which data on land use history and conservation values were available. The twenty-nine grasslands selected were non-fertilised and had an uninterrupted history of management, but they differed from each other in soil texture and grazing practices and were therefore sub-divided into six different types. Species abundance of mound-building ants were investigated in these grasslands in 2003. Additionally, ants were sampled using the pitfall trapping method in 13 semi-natural grasslands (in 2003 and 2005). Ant species richness and nest frequency of individual ant species differed between the different types of grassland and was associated with soil texture and grazing practices. The results also showed that even small grasslands have a very high ant species richness. This study showed that for the conservation of ants, habitat diversity and heterogeneity rather than habitat size are of great importance. I conclude that different types of semi-natural grassland contribute to heterogeneity in the farmland landscape and, thus, support higher ant diversity at the landscape scale.     

Arsenaufnahme von Wildpflanzen auf einem kampfstoffkontaminierten Rüstungsaltlastenstandort

The risk assessment of former ammunition factories, where chemical weapons consisting of diphenylarsenic compounds have been produced or stored is difficult because of the lack of data concerning bioavailability and metabolism of the residues of these sternutators. In order to estimate the contamination of fodder plants by typical pollutants of the former Heeresmunitionsanstalt Löcknitz, the total concentration of arsenic was determined in 186 samples of wild plants. The total arsenic concentration in plants of high feed value did not exceed 1 ppm, whereas 15% of the samples of plants of middle and little value in regard to animal fodder showed arsenic concentrations above 1ppm. The uptake of arsenic by wild plants, however, appears to be comparably low taken the high-grade contamination of the soil into account. A final toxicological evaluation of the risk potential is not yet possible because it requires the characterization of the anorganic and organic arsenic compounds in these plants.     

Different collector types for sampling deposition of polycyclic aromatic hydrocarbons--comparison of measurement results and their uncertainty

Different collector types, sample workup procedures and analysis methods to measure the deposition of polycyclic aromatic hydrocarbons (PAH) were tested and compared. Whilst sample workup and analysis methods did not influence the results of PAH deposition measurements, using different collector types changed the measured deposition rates of PAH significantly. The results obtained with a funnel-bottle collector showed the highest deposition rates and a low measurement uncertainty. The deposition rates obtained with the wet-only collectors were the lowest at industrial sites and under dry weather conditions. For the open-jar collectors the measurement uncertainty was high. Only at an industrial site with extremely high PAH deposition rates the results of open-jar collectors were comparable to those obtained with funnel-bottle collectors. Thus, if bulk deposition of PAH has to be measured, funnel-bottle combinations are proved to be the collectors of choice. These collectors were the only ones always fulfilling the requirements of European legislation.