Beitrag 3: Gedanken zum Schutzziel ‘Artengemeinschaften’

Within the context of the EU Water Framework Directive (EUWFD), there is a demand for a holistic quality improvement of aquatic systems. Therefore, it is obvious that biodiversity is one of the quality components and hence has to be considered in detail. The ranking of habitats, based on biodiversity indices, depends on the specific measurement selected. It is postulated that a ranking of habitats by means of a biodiversity index may be ambiguous. Concepts to resolve this dilemma are demonstrated, and a graphical formalism is introduced which up to now has only been used in quantum mechanics, statistical mechanics, and theoretical chemistry: The YOUNG-diagram technique.     

Bestimmung von Redoxzonen in einem mineralölbelasteten Grundwasserleiter

Goal and Scope

The goal of this study is the investigation and the grafic presentation of the characteristic redox zonation in a mineral oil contaminated aquifer which will be formed in the plume downstream of the contamination source. Methanogenic conditions, sulfate-reduction, Fe(III)-reduction, Mn(IV)-reduction, nitrate-reduction, aerobic conditions. By that indications type and degree of microbial degradation which is the most important part in Natural Attenuation (NA) processes can be obtained easily.

Methods

Changes of the groundwater parameters Eh, O₂, NO ₃ ^? , SO₄ ^2?, Fe²⁺, Mn²⁺, HCO₃ ^?, Ca²⁺ will be measured upstream, downstream and also in the centre of the plume. The results will be presented in a sequence of special diagrams.

Results and Conclusion

When microbial degradation of hydrocarbons takes place, a microbial community will always use that electron acceptor from which it will gain a maximum of energy by the corresponding redox-reactions. This means as long as oxygen is available this will be used. After its depletion nitrate serves as electron acceptor leading via nitrite to the formation of nitrogen or ammonia. Manganese (IV) and Iron (III) species which are rather insoluble are mainly available from the soil-phase, can act as electron acceptor as next, leading to soluble Manganese (II) and Iron (II) compounds in groundwater. Finally before methanogenic conditions occur sulphate will become a suitable electron acceptor leading to the formation of hydrogen sulphide. All these processes of mineralization of the hydrocarbons will lead to the production of CO₂ and as consequence to an increase of HCO₃ ^? in groundwater changing the calcareous/carbonic acid-equilibrium. By that more soluble Ca(HCO₃)₂ is formed from insoluble CaCO₃, so the concentration from Ca²⁺ will also inerease. Thus, by the action of microorganisms, a typical redox-zonation and changes of other parameters will occur.

Recommendations and Perspective

To follow the changes in time and space of some characteristic groundwater parameters is a simple way to estimate the potential of microbial degradation in a contaminated aquifer considering Natural Attenuation (NA)-processes.     

Anthropogenic emissions of methane and nitrous oxide in the Federal Republic of Germany

The anthropogenic emission sources of methane (CH₄) and nitrous oxide (N₂O) in the Federal Republic of Germany were investigated. The object of the recently completed first phase of this research project was to summarize the present knowledge about the emission sources, make a first rough estimate of the emissions, identify the need for further research in the field, and - as far as possible - discuss the existing possibilities to reduce emissions. The main CH₄ emission sources identified are the landfills, stock farming and pit mining, the main N₂O sources are agriculture (including a minor contribution from animal wastes) and the production of adipic acid, the latter possibly being reducible by means of a new catalytic process. The total anthropogenic emissions of CH₄ from Germany are estimated at 5.4 – 7.7 million tonnes per year, contributing a share of roughly 2 % to the world-wide anthropogenic emissions (350 million t/a). Those of N₂O are estimated at 200 000 – 280 000 tonnes per year (world-wide 1.4 – 6.5 million t/a).