Dissolved Phosphorus Concentrations in Surface Runoff from Agricultural Land Based on Calcium–Acetate–Lactate Soluble Phosphorus Soil Contents

The input of phosphorus (P) into aquatic systems can result in eutrophication that might manifest in algal blooms and oxygen deficiency and, subsequently, in a poor ecological status. Substance emission modeling on a river basin scale can help to quantify phosphorus emissions into surface water bodies and to address mitigation measures. The prerequisite is that suitable input data are available. The purpose of this study is to develop a modeling approach that allows the prediction of realistic phosphorus concentrations in surface runoff. During large-scale artificial rain experiments at 23 agricultural sites, dissolved P concentrations in surface runoff and subsurface flow were measured. The characteristics of the experimental sites were investigated by taking and analyzing soil samples and requesting information on the management from the farmers. From the data collected, two linear models were derived. The first model allows the prediction of dissolved phosphorus concentration in surface runoff from PCAL$_{soil}$ content. Applying the second model, the obtained concentration in surface runoff can be transferred to a concentration in subsurface flow. The resulting approaches were derived from realistic field experiments and, for the first time, allow the direct prediction of dissolved phosphorus concentrations in surface runoff and, in a second step, also in subsurface flow from spatially distributed PCAL$_{soil}$ content data. Integrating these approaches into substance emission models can improve their accuracy and, subsequently, allows a better planning of measures for the reduction in phosphorus emissions into surface water bodies

Four Years of Sediment and Phosphorus Monitoring in the Kraichbach River Using Large-Volume Samplers

Various sampling strategies come into operation to monitor water quality in rivers. Most frequently, grab samples are taken, but they are not suitable for recording the highly dynamic transport of solids and solid-bound pollutants. Composite samples reduce the influence of input and transport dynamics and are better suited to determine the annual river loads. Large-volume samplers (LVSs) produce both a composite sample over a long period of time and an amount of solids which allows for further analyses. In the small sub-catchment area of the Kraichbach river in Baden-Wuerttemberg (Germany) two LVSs have been installed to sample the river flow. The concentration of solids and phosphorus in the supernatant water and the settled sediment in the sampler have been determined and mean concentrations have been derived. Annual river loads were calculated in combination with discharge data from the nearby gauging station. Two sampling strategies of the LVS were tested and compared. For the first strategy, the LVS was used to collect quasi-continuous composite samples throughout the year, whereas, with the second strategy, samples were taken specifically for different flow conditions (low, mean and high flow). This study compares the advantages and constraints of both strategies. Results indicate that the first strategy is better suited to determine annual river loads. Quasi-continuous large-volume composite sampling is recommended for further monitoring campaigns

Use of monitoring approaches to verify the predictive accuracy of the modeling of particle-bound solid inputs to surface waters

For particle-bound substances such as phosphorus, erosion is an important input pathway to surface waters. Therefore, knowledge of soil erosion by water and sediment inputs to water bodies at high spatial resolution is essential to derive mitigation measures at the regional scale. Models are used to calculate soil erosion and associated sediment inputs to estimate the resulting loads. However, validation of these models is often not sufficiently possible. In this study, sediment input was modeled on a 10 × 10 m grid for a subcatchment of the Kraichbach river in Baden-Wuerttemberg (Germany). In parallel, large-volume samplers (LVS) were operated at the catchment outlet, which allowed a plausibility check of the modeled sediment inputs. The LVS produced long-term composite samples (2 to 4 weeks) over a period of 4 years. The comparison shows a very good agreement between the modeled and measured sediment loads. In addition, the monitoring concept of the LVS offers the possibility to identify the sources of the sediment inputs to the water body. In the case of the Kraichbach river, it was found that around 67% of the annual sediment load in the water body is contributed by rainfall events and up to 33% represents dry-weather load. This study shows that the modeling approaches for calculating the sediment input provide good results for the test area Kraichbach and the transfer for a German wide modeling will produce plausible values

Dissolved Phosphorus Concentrations in Surface Runoff from Agricultural Land Based on Calcium–Acetate–Lactate Soluble Phosphorus Soil Contents

The input of phosphorus (P) into aquatic systems can result in eutrophication that might manifest in algal blooms and oxygen deficiency and, subsequently, in a poor ecological status. Substance emission modeling on a river basin scale can help to quantify phosphorus emissions into surface water bodies and to address mitigation measures. The prerequisite is that suitable input data are available. The purpose of this study is to develop a modeling approach that allows the prediction of realistic phosphorus concentrations in surface runoff. During large-scale artificial rain experiments at 23 agricultural sites, dissolved P concentrations in surface runoff and subsurface flow were measured. The characteristics of the experimental sites were investigated by taking and analyzing soil samples and requesting information on the management from the farmers. From the data collected, two linear models were derived. The first model allows the prediction of dissolved phosphorus concentration in surface runoff from PCAL soil content. Applying the second model, the obtained concentration in surface runoff can be transferred to a concentration in subsurface flow. The resulting approaches were derived from realistic field experiments and, for the first time, allow the direct prediction of dissolved phosphorus concentrations in surface runoff and, in a second step, also in subsurface flow from spatially distributed PCAL soil content data. Integrating these approaches into substance emission models can improve their accuracy and, subsequently, allows a better planning of measures for the reduction in phosphorus emissions into surface water bodies

Four Years of Sediment and Phosphorus Monitoring in the Kraichbach River Using Large-Volume Samplers

Various sampling strategies come into operation to monitor water quality in rivers. Most frequently, grab samples are taken, but they are not suitable for recording the highly dynamic transport of solids and solid-bound pollutants. Composite samples reduce the influence of input and transport dynamics and are better suited to determine the annual river loads. Large-volume samplers (LVSs) produce both a composite sample over a long period of time and an amount of solids which allows for further analyses. In the small sub-catchment area of the Kraichbach river in Baden-Wuerttemberg (Germany) two LVSs have been installed to sample the river flow. The concentration of solids and phosphorus in the supernatant water and the settled sediment in the sampler have been determined and mean concentrations have been derived. Annual river loads were calculated in combination with discharge data from the nearby gauging station. Two sampling strategies of the LVS were tested and compared. For the first strategy, the LVS was used to collect quasi-continuous composite samples throughout the year, whereas, with the second strategy, samples were taken specifically for different flow conditions (low, mean and high flow). This study compares the advantages and constraints of both strategies. Results indicate that the first strategy is better suited to determine annual river loads. Quasi-continuous large-volume composite sampling is recommended for further monitoring campaigns

The Zugspitze Raman Lidar: System Testing

A high-power Raman lidar system has been installed at the high-altitude research station Schneefernerhaus (Garmisch-Partenkirchen, Germany) at 2675 m a.s.l., at the side of the existing wide-range differrential-absorption lidar. An industrial XeCl laser was modified for polarized single-line operation at an average power of about 175 W. This high power and a 1.5-m-diameter receiver are expected to allow us to extend the operating range for water-vapour sounding to more than 25 km, at an accuracy level of the order of 10 %. In addition, temperature measurements in the free troposphere and to altitudes beyond 80 km are planned. The system is currently thoroughly tested and exhibits an excellent performance up to the lowermost stratosphere. We expect that results for higher altitudes can be presented at the meeting

Modeling of Regionalized Emissions (MoRE) into Water Bodies: An Open-Source River Basin Management System

An accurate budget of substance emissions is fundamental for protecting freshwater resources. In this context, the European Union asks all member states to report an emission inventory of substances for river basins. The river basin management system MoRE (Modeling of Regionalized Emissions) was developed as a flexible open-source instrument which is able to model pathway-specific emissions and river loads on a catchment scale. As the reporting tool for the Federal Republic of Germany, MoRE is used to model annual emissions of nutrients, heavy metals, micropollutants like polycyclic aromatic hydrocarbons (PAH), Bis(2-ethylhexyl)phthalate (DEHP), and certain pharmaceuticals. Observed loads at gauging stations are used to validate the calculated emissions. In addition to its balancing capabilities, MoRE can consider different variants of input data and quantification approaches, in order to improve the robustness of different modeling approaches and to evaluate the quality of different input data. No programming skills are required to set up and run the model. Due to its flexible modeling base, the effect of reduction measures can be assessed. Within strategic planning processes, this is relevant for the allocation of investments or the implementation of specific measures to reduce the overall pollutant emissions into surface water bodies and therefore to meet the requirements of water policy.German Environment Agency (UBA