Hans Andersen
Aarhus University, Bioscience, Faculty Member
Research Interests:
In this paper we show the quantitative and relative importance of phosphorus (P) losses from agricultural areas within European river basins and demonstrate the importance of P pathways, linking agricultural source areas to surface water... more
In this paper we show the quantitative and relative importance of phosphorus (P) losses from agricultural areas within European river basins and demonstrate the importance of P pathways, linking agricultural source areas to surface water at different scales. Agricultural P losses are increasingly important for the P concentration in most European rivers, lakes, and estuaries, even though the quantity of P lost from agricultural areas in European catchments varies at least one order of magnitude (<0.2 kg P ha(-1) to >2.1 kg P ha(-1)). We focus on the importance of P for the implementation of the EU Water Framework Directive and discuss the benefits, uncertainties, and side effects of the different targeted mitigation measures that can be adopted to combat P losses from agricultural areas in river basins. Experimental evidence of the effects of some of the main targeted mitigation measures hitherto implemented is demonstrated, including: (i) soil tillage changes, (ii) treatment of soils near ditches and streams with iron to reduce P transport from source areas to surface waters, (iii) establishment of buffer zones for retaining P from surface runoff, (iv) restoration of river-floodplain systems to allow natural inundation of riparian areas and deposition of P, and (v) inundation of riparian areas with tile drainage water for P retention. Furthermore, we show how river basin managers can map and analyze the extent and importance of P risk areas, exemplified by four catchments differing in size in Norway, Denmark, and the Netherlands. Finally, we discuss the factors and mechanisms that may delay and/or counteract the responses of mitigation measures for combating P losses from agricultural areas when monitored at the catchment scale.
Research Interests:
Haderslev Dam is a 272 ha lake in southern Denmark with a high recreational value. For decades the lake has been severely eutrophicated due to excessive phosphorus loading. Major point sources were cut off in the early 1990s and an... more
Haderslev Dam is a 272 ha lake in southern Denmark with a high recreational value. For decades the lake has been severely eutrophicated due to excessive phosphorus loading. Major point sources were cut off in the early 1990s and an upstream wetland was recreated. However, the ecological quality remains unsatisfactory. In this study we estimate the importance of agriculture on diffuse phosphorus (P) input to the lake by modelling combined with independent estimates for contributions from scattered dwellings not connected to a sewer and from background losses. We apply a newly developed Danish P index to the lake catchment for mapping of risk areas for diffuse phosphorus losses. For risk areas we suggest mitigation measures and estimate the effect of the mitigation measures on the total P loading of the lake as well as the associated costs.
Research Interests:
Research Interests:
Research Interests: Earth Sciences, Climate Change, Wetlands, Structure, Irrigation, and 32 moreBiomass, Control, Climate, Aquatic Plants, Eutrophication, Biological Sciences, Phosphorus, Denmark, Environmental Sciences, Water Supply, Animals, Evapotranspiration, Nitrogen, Community Structure, Zooplankton, Sediment, Climatic Change, Climate Model, Environmental quality, Theoretical Models, Greenhouse Effect, Ecosystem, Critical Loads, Streams, Predators, Fresh water, Runoff, Predator control, Soil Type, Soil Types, Environment Quality, and Chlorophyll a
An important step in the implementation of the Water Framework Directive is to define and characterize the natural status, designated as the reference condition (RC). Here we present the results of a type-specific screening for reference... more
An important step in the implementation of the Water Framework Directive is to define and characterize the natural status, designated as the reference condition (RC). Here we present the results of a type-specific screening for reference stream sites in Denmark using two different approaches. First, we performed a screening applying physicochemical, hydro-morphological and pressure criteria at the catchment, reach and site level of a total of 128 sites a priori selected by the regional water authorities as representing the best sites in Denmark. Second, we performed a GIS screening of all mapped streams in Denmark (26,000 km representing app. 90% of all Danish streams) using solely land use characteristics in the catchment area to target the search for larger stream sites to comply with the WFD requirements of type-specificity. Among the 128 sites we did not find any that fulfilled all criteria applied at the catchment, reach and site level using recommended RC threshold values and only three sites using threshold values that were less strict. Similarly very few km (<1%) of the GIS screened streams fulfilled catchment land use criteria, suggesting that the potential of identifying RC sites in Denmark is very limited. The lack of success in the screening process clearly demonstrates a need for alternative methods to establish RC for Danish streams. We propose a combined approach that includes the development of a guiding image for RC for all the stream biota needed to evaluate the ecological quality. This guiding image should be based on historical data, expert knowledge and investigations in streams situated in countries that are subjected to less intense land use and, at the same time, share both topographical and climatic similarities with Denmark, e.g. the Baltic countries.
Research Interests:
Research Interests: Agriculture, Environmental Monitoring, Rivers, Phosphorus, Environmental Sciences, and 14 moreStandard Deviation, Europe, Land Use, Nitrogen, Coefficient of Variation, Agricultural land use change, CHEMICAL SCIENCES, Theoretical Models, Nutrient Loading, Soil Type, Conservation of Natural Resources, Water Movements, Nutrient Loss, and Simulation Model
Research Interests: Soil, Agriculture, Environmental Monitoring, Rivers, Phosphorus, and 17 moreEnvironmental Sciences, Europe, Performance Model, Surface Water, Nitrogen, Root-Mean Square Error, Agricultural land use change, CHEMICAL SCIENCES, Theoretical Models, total P, Reproducibility of Results, Nutrient Loading, Conservation of Natural Resources, Total Nitrogen, Total Phosphorus, Water Movements, and Nutrient Loss
Research Interests:
Research Interests: Earth Sciences, Climate Change, Temperate Forests, Biological Sciences, Phosphorus, and 13 moreSeasonality, Environmental Sciences, Ecology of Submerged Macrophyte, Cropping Pattern, Evapotranspiration, Land Use, Surface Water, Nitrogen, Water Use, Arid Zone, Streams, Sewage Treatment, and Subtropics
Research Interests: Agriculture, Environmental Monitoring, Rivers, Biodiversity, Multidisciplinary, and 14 moreWater Supply, Animals, Land Use, Decision Tree Classification, Fishes, Cluster Analysis, Cost effectiveness, Spatial Scale, Trees, Human impact, Environmental monitoring and assessment, Fish Assemblage, Geographic Information Systems, and Conservation strategies
Northern forests in North America contain a vast amount of sequestered carbon that is potentially vulnerable to climate change. Scientists from Canada and the US are working in close collaboration to assess the capacity of the GLAS lidar... more
Northern forests in North America contain a vast amount of sequestered carbon that is potentially vulnerable to climate change. Scientists from Canada and the US are working in close collaboration to assess the capacity of the GLAS lidar sensor on the ICESAT satellite to estimate the amount, spatial distribution and statistical uncertainty of aboveground tree biomass of these forests. A