Glossary

Insecticide that works as a contact and stomach poison and has been used since the early 1940s. DDT is an example of a persistent chlorinated hydrocarbon. Its use has been prohibited in most industrialised countries since the 1970s. In 2004, its international use was restricted to the sole purpose of combating malaria vectors. The substance is highly stable and is broken down very slowly in the environment. As a result, it has become ubiquitous in the environment and is even contained in breast milk. DDT is mutagenic and suspected of being carcinogenic.

See ►DSS.

Dehalogenation is the removal of halogens (especially chlorine) from organic compounds. In a narrower sense, the term refers to the removal of halogens from ►volatile halogenated hydrocarbons (VHHC). Volatile halogenated hydrocarbons (VHHC) with up to three chlorine atoms can be dehalogenated through microbial activity.

Process in which bacteria break down nitrate and release nitrogen (N₂) as it occurs in the air. Byproducts of denitrification are nitrous oxide (N₂O) and nitrogen oxide (NO_x).

Process of gradual desert formation in arid areas.

A tower-like vessel constructed from concrete, prestressed concrete or steel and used in wastewater treatment for the controlled and regulated execution of ► anaerobic degradation processes. Just like other digestion tanks, digesters are usually found in sewage plants. The digested sludge is used to break down fermentation gases such as methane (CH4), which must be captured or combusted due its high global warming potential. The captured gas can be converted into energy, particularly for the generation of power in a combined heat and power plant.

Procedure used for depthoriented groundwater sampling. A special filter probe is advanced directly into the aquifer at the required depth, thus enabling groundwater sampling from pre-defined depth ranges.

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DOC stands for dissolved organic carbon. It combines with the particulate organic carbon (POC) and the volatile organic carbon (VOC) to form the total organic carbon (TOC). This organic sum parameter indicates the organic substance dissolved in water.

These serve as a substitute for natural, water-permeable drainage layers consisting of, for example, expanded clay, lava, gravel or expanded shale. Drainage elements are used for the mechanical stabilisation of the substrate and to prevent water retention and are therefore often employed in dyke construction, among other things.

Computer-based tool that assists decision-makers in evaluating information and assessing the impact of different courses of action.

Dynamic drilling is a simple means of analysing the soil structure and extracting samples using a hollow steel probe that is driven into the ground.