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Fine insoluble mineral or organic particles in the water phase

Suspended particulate matter (SPM) is the third important structural and functional element in aquatic ecosystems next to the water phase and the sediment. Origin, quantity and quality of the SPM are specific for each water body and depend on the respective catchment area (geology, land use, urbanisation, state of waste water treatment technology, etc.). The chemical and biological composition of SPM is further influenced by the season, the nutrient supply, the water outflow and the weather conditions.
The quantity of SPM in the water phase plays an important role for the total load of organic and inorganic substances because a significant but varying portion of these substances is transported particle-bound. The binding of hydrophobic organic compounds, for instance, is driven by the concentrations of organic carbon.
Depending on flow velocity, particle size and density, SPM either sediment (low flow velocity) or whirl up (high flow velocity). This may cause deposition of contaminated SPM in back waters, regulated water bodies and harbours. On the other hand, floods, dredging and ships may lead to a significant remobilisation of sediments accompanied by increased contaminant levels in the water phase.
These considerations illustrate the complex function of SPM and sediment as sink, transport vehicle and source of particle-bound substances. SPM is therefore crucial in assessing the contamination of surface waters.

For the Environmental Specimen Bank SPM with a particle size of < 2 mm is sampled using special devices (sedimentation boxes). The samples include small organisms (e.g. crustaceans, worms) which fall through the sieves and are not capable of escaping.

Samples are taken every month.