The objective of this paper is to present a model based approach to identify the demand for measures for the reduction of nitrogen surpluses from agriculture and to compose a combination of possible measures with their associated costs to be able to meet the targets of the water framework directive (WFD). An interdisciplinary model network consisting of the regionalised agricultural economic model RAUMIS and two hydro(geo)logical modelling systems GROWA/WEKU and MONERIS is used to analyse the spatially differentiated impacts of nutrient reduction measures on the water quality of groundwater and surface water. The study region of the German Weser river basin is chosen that comprises 49,000 km2 and features heterogeneous natural site conditions. In order to support the preparation of a management plan for the Weser river basin the AGRUM Weser project has been initiated. A combination of measures is specified for each county in the Weser basin depending on regional peculiarities and farming practices. Results show that about 100 million Euros per year are needed for agri-environmental measures to fulfil the objectives of the Water Framework Directive. This paper presents a regionally comprehensive and area wide modelling approach that is capable of linking hydrological and agricultural economic aspects in an interdisciplinary approach and which can easily be transferred to other river basins.
Water framework directive, Diffuse pollution, Agricultural economic and hydrological modelling, Cost of nutrient reduction measures, Weser River Basin
Kreins, P., Gömann, H., Heidecke, C., Hirt, U., Wendland, F., 2010. Modelling network for analysing diffuse nitrogen leaching reduction in agriculture to meet the targets of the water framework directive in the Weser River Basin of Germany. In: Steusloff, H. (ed.). IWRM Integrated Water Resources Management Karlsruhe: KIT Scientific Publishing, pp. 200-206.
While the use of plastic materials has generated huge societal benefits, the ‘plastic age’ comes with downsides: One issue of emerging concern is the accumulation of plastics in the aquatic environment. Here, so-called microplastics (MP), fragments smaller than 5 mm, are of special concern because they can be ingested throughout the food web more readily than larger particles. Focusing on freshwater MP, we briefly review the state of the science to identify gaps of knowledge and deduce research needs.
State of the science
Environmental scientists started investigating marine (micro)plastics in the early 2000s. Today, a wealth of studies demonstrates that MP have ubiquitously permeated the marine ecosystem, including the polar regions and the deep sea. MP ingestion has been documented for an increasing number of marine species. However, to date, only few studies investigate their biological effects.
The majority of marine plastics are considered to originate from land-based sources, including surface waters. Although they may be important transport pathways of MP, data from freshwater ecosystems is scarce. So far, only few studies provide evidence for the presence of MP in rivers and lakes. Data on MP uptake by freshwater invertebrates and fish is very limited.
While the research on marine MP is more advanced, there are immense gaps of knowledge regarding freshwater MP. Data on their abundance is fragmentary for large and absent for small surface waters. Likewise, relevant sources and the environmental fate remain to be investigated. Data on the biological effects of MP in freshwater species is completely lacking. The accumulation of other freshwater contaminants on MP is of special interest because ingestion might increase the chemical exposure. Again, data is unavailable on this important issue.
MP represent freshwater contaminants of emerging concern. However, to assess the environmental risk associated with MP, comprehensive data on their abundance, fate, sources, and biological effects in freshwater ecosystems are needed. Establishing such data critically depends on a collaborative effort by environmental scientists from diverse disciplines (chemistry, hydrology, ecotoxicology, etc.) and, unsurprisingly, on the allocation of sufficient public funding.
Chemistry, Ecotoxicology, Environmental quality, Litter, Microplastics, Monitoring, Plastics, Polymers, Review, Water framework directive
Martin Wagner, Christian Scherer, Diana Alvarez-Muñoz, Nicole Brennholt, Xavier Bourrain, Sebastian Buchinger, Elke Fries, Cécile Grosbois, Jörg Klasmeier, Teresa Marti, Sara Rodriguez-Mozaz, Ralph Urbatzka, A. Dick Vethaak, Margrethe Winther-Nielsen & Georg Reifferscheid (2014): Microplastics in freshwater ecosystems: what we know and what we need to know. Environmental Sciences Europe 26:12.