Natural background concentrations of nutrients in the German Bight area (North Sea)

Natural background concentrations of nutrients are needed for the assessments of eutrophication processes and their status. Natural background concentrations of total nitrogen (TN) and total phosphorus (TP) were modelled for the rivers discharging into the German Bight and the Rhine considering individual catchment sizes, freshwater flows and soil types. These data were validated by comparison with data from unpolluted rivers. The consistency of modelled and some compiled nutrient concentrations was confirmed by their area-specific load dependency on freshwater discharges. Pristine inorganic nutrient concentrations were deduced from modelled relations to TN and TP in unpolluted rivers. Pristine nutrient gradients between rivers and offshore waters were estimated by linear mixing until a salinity of 32, continued by hyperbolic fits towards recent mean offshore values (salinity 34.5?C35). Based on these gradients and recent mean salinities, maps of pristine surface gradients were plotted for the whole German Bight. Variability was transferred from recent conditions as percentage of standard deviation. Reported historical nutrient data and concentrations from unpolluted rivers, coastal and offshore North Sea waters are discussed concerning their relations to natural background conditions.     

Modelling the fate of organic chemicals in the soil plant environment: Model study of root uptake of pesticides

The fate of organic chemicals in the soil-plant-atmosphere environment and the governing processes were studied with a coupled dynamic soil transport and plant compartment model. Scenarios with applications of pesticides on sand and loam soils with chemical uptake in barley and wheat were used in the model calculations. Root uptake and concentrations in the plant compartments stem, leave and fruit were calculated for the pesticides terbuthylazine, isoproturon and carbofuran.

The effectivity of uptake from soils with different soil sorption coefficients had been shown for sand and loam soils. The processes degradation in plant and volatilization from leaves to atmosphere are especially effective for carbofuran and terbuthylazine. Although the concentrations in corn at harvest are lower than the maximum allowed concentrations, the peak concentrations in the course of the vegetation period are significantly higher (factor ≤ 200).     

A universal method to assess the potential of phosphorus loss from soil to aquatic ecosystems

Background, aim, and scope  

Phosphorus loss from terrestrial to the aquatic ecosystems contributes to eutrophication of surface waters. To maintain the world's vital freshwater ecosystems, the reduction of eutrophication is crucial. This needs the prevention of overfertilization of agricultural soils with phosphorus. However, the methods of risk assessment for the P loss potential from soils lack uniformity and are difficult for routine analysis. Therefore, the efficient detection of areas with a high risk of P loss requires a simple and universal soil test method that is cost effective and applicable in both industrialized and developing countries.     

Gas separation using porous cement membrane

Gas separation is a key issue in various industrial fields. Hydrogen has the potential for application in clean fuel technologies. Therefore, the separation and purification of hydrogen is an important research subject. CO2 capture and storage have important roles in ＂green chemistry＂. As an effective clean technology, gas separation using inorganic membranes has attracted much attention in the last several decades. Membrane processes have many applications in the field of gas separation. Cement is one type of inorganic material, with the advantages of a lower cost and a longer lifespan. An experimental setup has been created and improved to measure twenty different cement membranes. The purpose of this work was to investigate the influence of gas molecule properties on the material transport and to explore the influence of operating conditions and membrane composition on separation efficiency. The influences of the above parameters are determined, the best conditions and membrane type are found, it is shown that cementitious material has the ability to separate gas mixtures, and the gas transport mechanism is studied.     

Absorption of odourous substances using selective gas-liquid separation processes

Absorption is one of the most widely used techniques for treating odourous waste gases. An improvement of the effectiveness of gas scrubbers can be achieved by using adapted washing liquids. A screening test is proposed as a low cost tool for testing washing liquids on industrial waste gases. The odour index is used to identify the main cause of the specific smell and to simplify the analysis of absorptive performances of washing liquids. The method is verified by experiments at a chocolate factory and a fat and oil refinery.     

Evaluation of factors influencing soluble microbial product in submerged MBR through hybrid ASM model

In this study, a mathematical model was established to predict the formation of the soluble microbial product (SMP) in a submerged membrane bioreactor. The developed model was calibrated under the reference condition. Simulation results were in good agreement with the measured results under the reference condition. The calibrated model was then used in the scenario studies to evaluate the effect of three chosen operating parameters: hydraulic retention time (HRT), dissolved oxygen concentration, and sludge retention time (SRT). Simulation results revealed that the SMP dominated the soluble organic substances in the supernatant. The scenario studies also revealed that the HRT can be decreased to 1 h without deteriorating the effluent quality; dissolved oxygen concentration in the reactor can be kept at 2–3 mg/L to maintain the effluent quality, reduce the content of SMP, and minimize operating costs; the optimal SRT can be controlled to 10–15 d to achieve complete nitrification process, less membrane fouling potential, and acceptable organic removal efficiency.     

Uptake of terbuthylazine and its medium polar metabolites into maize plants

The uptake of terbuthylazine and its medium polar metabolites into maize plants under outdoor conditions is investigated. For this purpose, a dynamical fate model consisting of soil, plant and air is developed. The model calculations are compared with experimental results of outdoor lysimeter tests, carried out with¹⁴C-labelled herbicide applied to sandy agricultural soil at a single application rate of 890 g/ha. Approximately 0.3 % of the applied activity remains in all the plants after the vegetation period. The model predicts that about three times that amount is volatilized from the plants into the air. Activity uptaken from soil and volatilized from plant surface into air is predominately associated with metabolites. During the whole vegetation period the fraction of unchanged terbuthylazine in the plants is very small (less than 1 % of the extractable activity).     

Phosphorus losses from agricultural areas in river basins: effects and uncertainties of targeted mitigation measures

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.