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With respect to groundwater quality objectives, it is difficult to understand the nitrogen balance and nitrogen dynamics of agricultural ecosystems without the support of deterministic and stochastic simulation tools. This paper focuses on the deterministic and stochastic modelling of water, heat and nitrogen dynamics in the soil compartments of agricultural ecosystems. The deterministic nitrogen simulation model for agricultural soils presented in this paper, WHNSIM, was originally designed for site conditions typical of southern Germany but can easily be applied to other regions due to its physically based design. Model results are compared with data originating from different experimental sites in Germany. Special consideration is given to the effects of spatial variability. Two different techniques of Monte Carlo simulation are used to study the impact of parameter variability on target variables of nitrogen dynamics on the field scale. Moreover, a procedure is presented that allows modelling nitrogen dynamics on the scale of small catchment areas, combining the geographical information system Arc Info with agricultural management data and model calculations. 相似文献
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Hard (nonbiodegradable) nonionic surfactants are the most commonly used nonionics in Israel. This has no parallel in western industrial countries. Consequently, available methods for nonionic determination should be appropriately applied and validated under the particular local in vivo conditions. This study presents preliminary results of the application of modified available analycal hydrophilic and hydrophobic methods and procedures for nonionic detergents determination to the complex system of typical sewage effluents in Israel under in vitro (laboratory controlled), simulative, semi-in vivo, and in vivo (real, uncontrolled) local field conditions. Using the hydrophilic Cobalto thiocyanate method and applying several essential modifications and transformations have facilitated the obtaining of “summative,” averaged, factorized calibration curves which represent the local environmental reality. Based on the above in vitro-in vivo transformations, an unexpected low concentration of nonionic surfactants (3–4 mg/L) has been determined in typical local municipal sewage effluents. 相似文献
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The anaerobic biodegradability of wastewaters from different chemical plants was determined by an integrated test strategy consisting of an anaerobic toxicity test, a static anaerobic biodegradation test and a continuously operated fixed bed reactor test. This integrated procedure offered a useful tool for screening wastewaters for anaerobic biodegradability. Four different wastewaters were tested for anaerobic toxicity and biodegradability. One wastewater was used in subsequent testing in a fixed bed reactor which aimed to illustrate a potential design of an anaerobic treatment plant. 相似文献
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