Determination of volatile organic sulfur compounds in contaminated groundwater

A practical method for the quantification of total purgeable organic sulfur (POS) in highly contaminated groundwater is described. Volatile organic sulfur compounds (VOSC) are purged from the water samples by a stream of oxygen and combusted. The emerging sulfur dioxide is absorbed in H₂O₂ and converted to sulfate which is quantified by ion chromatography and reported as mass sulfur equivalent. The overall limit of quantification is 0.03 mg l⁻¹. The content of POS is balanced with the total VOSC determined by GC-AED after liquid–liquid extraction. Separate determination of the non-volatile organic sulfur compounds by direct combustion of the water sample and adsorption to charcoal yielded a mass balance of the total sulfur content. Semi-quantitative GC-MS after purge & trap accumulation revealed that the VOSC mixture is composed of C₁–C₄ alkyl sulfides. The implementation of the developed methodology for the quantification of VOSC as potential catalyst poison in a cleaning plant for groundwater contaminated with volatile haloorganics (VOX) is presented.     

Land cover composition determinants in the Uckermark (NE Germany) over a 220-year period

There is broad consensus that land use/cover has changed in central Europe over millennia. However, few studies have addressed the roles of the anthropogenic (socio-economic) and natural (biophysical) factors driving these changes over shorter periods (e.g., 100 years). In this study, we analyse the determinants of land cover composition at three discrete time periods (c. 1780, 1890, and 2000). We hypothesise that different anthropogenic and natural factors are the determinants of the main land cover types (arable fields, grasslands, and forests) and that the effects of natural and anthropogenic factors on the main land cover types differ among landscapes with highly dynamic and more stable forest-open land distributions. The study was carried out in the Uckermark region located in northeastern Germany. We compiled data on natural and anthropogenic factors (e.g. forest cover and number of inhabitants) of 65 municipalities in four landscape sections of equal size (10 × 10 km). Landscape sections were selected to reflect different dynamics (high/low) in conversion from forest to arable fields or grasslands and vice versa from 1780 to 2000. Averaged linear mixed-effect models explained between 7.5 and 81.2 % of the variance. The unique effect of anthropogenic factors varied from 2.1 to 18.7 % and that of natural factors varied from 0.2 to 43.4 %. In four of six models that included both types of factors, the natural factors were more influential than the anthropogenic factors. Except in three cases, anthropogenic and natural factors showed opposite effects on land cover types in more dynamic and more stable windows. Though the Uckermark region has been influenced by human activity for thousands of years, natural factors were a major determinant of land cover composition during all time periods, whereas anthropogenic factors became more important only during the latest time period under investigation.     

How to improve reliability in groundwater analysis: over a decade of experience with external quality control in field campaigns on volatile halogenated compounds

The reliability in measurement results obtained during environmental monitoring is crucial for the assessment and further planning of remediation efforts on the respective contaminated sites by the responsible authorities. A case study concerned with groundwater contaminated with perchloroethylene, trichloroethylene and 1,1,2-trichlorotrifluoroethane including their degradation products which involves private contract laboratories and an independent provider of quality assurance (QA) is presented. The experience gained with biannual monitoring campaigns over 14 years indicates that the selection of contractors on basis of accreditation status and successful performance in interlaboratory comparisons are not sufficient. Rather the auditing of the contractors by the QA provider prior to each campaign and the crosschecking of selected monitoring samples by the QA provider led to a lasting improvement of reliability in the contractors' measurement results. A mean deviation of 20% from the reference value determined by the QA provider for the crosschecked samples was reached.     

The prevention principle

Environmentally sound manufacture does not have its source only in developing and improving the techniques for treating solid, liquid and gaseous wastes at the end of the production process. Our experience shows that more effort and capital budgets must be devoted to developing preventive measures. Although the treatment techniques have become very advanced and meet ecological requirements to a very high degree, they are now reaching the limits of their technological and economic feasibility. Environmental protection at the production site has undergone structural change in recent years. The emphasis has shifted to preventive techniques which affect the production process itself, avoiding the emergence of waste at the “end of the pipe” by preventing its formation or recycling it straight away. This integrated approach is in harmony with the demands of sustainable production. The functions of in-process environmental protection measures need to be looked at as a whole from the points of view of both environmental protection and cost-effectiveness. Some integrated methods are described.     

Contributions of paraecologists and parataxonomists to research,conservation, and social development

Citizen science has been gaining momentum in the United States and Europe, where citizens are literate and often interested in science. However, in developing countries, which have a dire need for environmental data, such programs are slow to emerge, despite the large and untapped human resources in close proximity to areas of high biodiversity and poorly known floras and faunas. Thus, we propose that the parataxonomist and paraecologist approach, which originates from citizen‐based science, is well suited to rural areas in developing countries. Being a paraecologist or a parataxonomist is a vocation and entails full‐time employment underpinned by extensive training, whereas citizen science involves the temporary engagement of volunteers. Both approaches have their merits depending on the context and objectives of the research. We examined 4 ongoing paraecologist or parataxonomist programs in Costa Rica, India, Papua New Guinea, and southern Africa and compared their origins, long‐term objectives, implementation strategies, activities, key challenges, achievements, and implications for resident communities. The programs supported ongoing research on biodiversity assessment, monitoring, and management, and participants engaged in non‐academic capacity development in these fields. The programs in Southern Africa related to specific projects, whereas the programs in Costa Rica, India, and Papua New Guinea were designed for the long term, provided sufficient funding was available. The main focus of the paraecologists’ and parataxonomists’ activities ranged from collection and processing of specimens (Costa Rica and Papua New Guinea) or of socioeconomic and natural science data (India and Southern Africa) to communication between scientists and residents (India and Southern Africa). As members of both the local land user and research communities, paraecologists and parataxonomists can greatly improve the flow of biodiversity information to all users, from local stakeholders to international academia.     

Effect of contact time on the release of contaminants from granular waste materials during column leaching experiments

When reusing or disposing of contaminated granular waste materials there is a need to evaluate how the contaminants will interact on the pathway soil–groundwater and the effect this interaction will have on the surrounding environment. While column testing can provide a closer approximation to field percolation conditions than batch testing, there is still a need to develop column testing procedures that consider the requirements of practical testing time frames. This study evaluates the effect of different column contact times (2.5, 5, and 16 h) on the release of inorganic constituents from bottom ash and demolition waste, two commonly reused granular materials. Leaching data for representative constituents of concern, such as copper, chromium, sulfate and chloride, as well as pH and electrical conductivity was compared for all different contact times studied.Results for the materials investigated in this study showed that variations in contact time have no significant effect on the release of the selected constituents and leaching parameters at low liquid to solid ratios. However, after a liquid to solid ratio of 1 L/kg, the effect is more noticeable, and higher contact times show lower pH values as well as a reduction in the release of constituents of concern from bottom ash. In the case of demolition waste, the variation of contact time did not have a strong effect on the leaching behavior.     

Spatial variability of soil gas concentration and methane oxidation capacity in landfill covers

In order to devise design criteria for biocovers intended to enhance the microbial oxidation of landfill methane it is critical to understand the factors influencing gas migration and methane oxidation in landfill cover soils. On an old municipal solid waste landfill in north-western Germany soil gas concentrations (10, 40, 90 cm depth), topsoil methane oxidation capacity and soil properties were surveyed at 40 locations along a 16 m grid. As soil properties determine gas flow patterns it was hypothesized that the variability in soil gas composition and the subsequent methanotrophic activity would correspond to the variability of soil properties. Methanotrophic activity was found to be subject to high spatial variability, with values ranging between 0.17 and 9.80 g CH₄ m⁻² h⁻¹_. Considering the current gas production rate of 0.03 g CH₄ m⁻² h⁻¹, the oxidation capacity at all sampled locations clearly exceeded the flux to the cover, and can be regarded as an effective instrument for mitigating methane fluxes. The methane concentration in the cover showed a high spatial heterogeneity with values between 0.01 and 0.32 vol.% (10 cm depth), 22.52 vol.% (40 cm), and 36.85 vol.% (90 cm). The exposure to methane raised the oxidation capacity, suggested by a statistical correlation to an increase in methane concentration at 90 cm depth. Methane oxidation capacity was further affected by the methanotroph bacteria pH optimum and nutrient availability, and increased with decreasing pH towards neutrality, and increased with soluble ion concentration). Soil methane and carbon dioxide concentration increased with lower flow resistance of the cover, as represented by the soil properties of a reduced bulk density, increase in air capacity and in relative ground level.     

Sociogenetic structure in a free-living nocturnal primate population: sex-specific differences in the grey mouse lemur (Microcebus murinus)

The grey mouse lemur (Microcebus murinus) has a dispersed social structure, within which female sleeping associations are common. These sleeping associations have been hypothesised to confer anti-predatory and thermoregulatory benefits, especially when rearing offspring. The genetic composition of these associations was determined using microsatellite markers to test predictions derived from kin selection theory. 161 (99 males, 62 females) individual M. murinus belonging to a free-living population in Ampijoroa, north-western Madagascar, were genotyped and observed over a total of 13 months distributed over the dry seasons of 3 successive years (1995-1997). Kin selection theory predicts that these female associations should consist of closely related members, and that female philopatry and male natal dispersal should characterise the dispersal pattern within this species. These predictions were confirmed by the data. Five out of six female sleeping groups consisted of one or more closely related dyads. Females that slept alone did not have close female kin in the vicinity or within the population at all. Closely related female dyads lived in significantly closer proximity than closely related male dyads and closely related male-female dyads showed intermediate proximity. In combination with the result that females possessed significantly more relatives within the population than males, these findings support the behavioural hypotheses of female philopatry and male natal dispersal. Matrilinear grouping patterns and sex-biased dispersal are therefore genetically established in a dispersed primate social organisation for the first time. The results further indicate that several generations of mouse lemurs live together within a given area, implying both an effective mechanism of kin recognition to avoid father-daughter incest and the potential for social learning to ensure individual recognition.