Simulating Soil Organic Matter Transformations with the New Implementation of the Daisy Model

Daisy is a well-tested deterministic, dynamic soil-plant-atmosphere model, capable of simulating water balance, nitrogen balance and losses, development in soil organic matter and crop growth and production in crop rotations under alternate management strategies. Originally it was developed as a system of single models describing each process involved, but recently it has been developed into a framework, which can be used for implementation of several different models of each of the different processes. Thus, for example a number of different models for simulating soil water dynamics can be chosen depending on the purpose of the simulation and the availability of data for parameterisation. The sub-model simulating soil organic matter is still a fixed component in the Daisy terminology. This means that there is currently only one model, which can be used to simulate soil organic matter transformations. However this sub-model can be changed considerably. Some examples are given

Toarcian oceanic anoxic event: An assessment of global causes using belemnite C isotope records

Two hypotheses have been proposed to explain simultaneous large negative excursions (up to 7% PeeDee belemnite) in bulk carbonate (delta(13)C(carb)) and organic carbon isotope records (delta(13)C(org)) from black shales marking the Toarcian oceanic anoxic event (T-OAE). The first explanation envisions recycling of dissolved inorganic carbon (DIC) with a light isotopic signature into the photic zone from the lower levels of a salinity-stratified water mass, essentially requiring a regional paleoceanographic driver of the carbon cycle. The second involves the rapid and massive dissociation of methane from gas hydrates that effectively renders the T-OAE a global perturbation of the carbon cycle. We present C isotope records from belemnites (delta(13)C(bel)) sampled from two localities, calibrated with high-resolution ammonite biostratigraphy and Sr isotope stratigraphy, in Yorkshire (England) and Dotternhausen (Germany), that can be used to assess which model best explains the observed changes in carbon isotopes. Our records of the delta(13)C composition of belemnite calcite do not show the large negative C isotope excursions shown by coeval records of delta(13)C in sedimentary organic matter or bulk sedimentary carbonate. It follows that isotopically light carbon cannot have dominated the ocean-atmosphere carbon reservoir during the Toarcian OAE, as would be required were the methane release hypothesis correct. On the basis of an evaluation of available carbon isotope records we discuss a model in which the recycling of DIC from the deeper levels of a stratified water body, and shallowing of anoxic conditions into the photic zone, can explain all isotopic profiles. In particular, the model accounts for the higher C isotope values of belemnites that are characteristic of open ocean, well-mixed conditions, and the lower C isotope values of neritic phytoplankton communities that recorded the degree of density stratification and shallowing of anoxia in the photic zone

Contents : Annual Report of FY 2006, The Core University Program between Japan Society for the Promotion of Science (JSPS) and Vietnamese Academy of Science and Technology (VAST)

Joint Research on Environmental Science and Technology for the Eart

Modeled nitrogen loading to Narragansett Bay: 1850 to 2015

Nutrient loading to estuaries with heavily populated watersheds can have profound ecological consequences. In evaluating policy options for managing nitrogen (N), it is helpful to understand current and historic spatial loading patterns to the system. We modeled N inputs to Narragansett Bay from 1850 to 2000, using data on population, human waste disposal, livestock, fertilizer, and atmospheric deposition. We found that total N loading to the bay increased 250% from 1850 to 2000, and 80% from 1900 to 2000. Loading to the upper bay increased far more than that to the lower bay, and the most important source shifted from non-point animal waste to human waste concentrated at sewage treatment facilities. We also modeled future N loads in 2015 under four management scenarios. Planned improvements in sewage treatment would reduce N loads 9% below business-as-usual, to the 1990 loading rate. Greater reductions, to circa 1900 rates of loading, may be possible

DENITIRIFICATION TREATMENT OF NITRIFIED HANOI GROUNDWATER USING SWIM BED TECHNOLOGY

Joint Research on Environmental Science and Technology for the Eart

A nitrogen model for European catchments: INCA, new model structure and equations

International audienceA new version of the Integrated Nitrogen in Catchments model (INCA) was developed and tested using flow and streamwater nitrate concentration data collected from the River Kennet during 1998. INCA is a process-based model of the nitrogen cycle in the plant/soil and in-stream systems. The model simulates the nitrogen export from different land-use types within a river system, and the in-stream nitrate and ammonium concentrations at a daily time-step. The structure of the new version differs from the original, in that soil-water retention volumes have been added and the interface adapted to permit multiple crop and vegetation growth periods and fertiliser applications. The process equations are now written in terms of loads rather than concentrations allowing a more robust tracking of mass conservation when using numerical integration. The new version is able to reproduce the seasonal dynamics observed in the streamwater nitrogen concentration data, and the loads associated with plant/soil system nitrogen processes reported in the literature. As such, the model results suggest that the new structure is appropriate for the simulation of nitrogen in the River Kennet and an improvement on the original model. The utility of the INCA model is discussed in terms of improving scientific understanding and catchment management. Keywords: modelling, water quality, nitrogen, nitrate, River Kennet, River Thames</p

Atmospheric deposition at groundwater dependent wetlands: implications for effective catchment management and Water Framework Directive groundwater classification in England and Wales

This report is the product of an Environment Agency (EA) contract co-funded by the British Geological Survey (NERC) to review and collate information regarding atmospheric and terrestrial nutrient loading at groundwater dependent terrestrial ecosystems (GWDTEs) in both England and Wales (the inclusion of Welsh sites are covered by the co-funding from BGS and not from EA funding. Many GWDTEs are low nutrient systems therefore any increase in loading can have a detrimental effect upon the ecology. In order to better protect GWDTEs in England and Wales it has become increasingly important to understand the sources of nutrients so that effective regulation and management can be applied to return the GWDTEs into favourable condition. This report highlights many knowledge gaps and also provides the first comparison of two national assessments, Critical Load (assessment of atmospheric deposition) and Threshold Value (assessment of groundwater nitrate levels). It shows that nearly 90% of the GWDTEs in England and Wales exceed their Critical Load for atmospheric deposition. Implications for future Water Framework Directive classification cycles are highlighted. Suggestions are made for suitable GWDTEs to be included in a future research project. The project will aim to provide a methodology to define source attribution from both atmospheric and terrestrial nutrients, enabling environment managers to make effective decisions to project GWDTEs

Phytochemical and Antibacterial Properties of Leaf Extracts of Ipomoea asarifolia

The antibacterial potency of aqueous and methanol extracts of Ipomoea asarifolia leaves; a plant widely used by traditional medical practitioners in Nigeria was determined in vitro against three bacterial pathogens (Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa) by agar well diffusion method. The pattern of inhibition varied with the extracts and the organisms tested. Both the aqueous and methanol extracts were potent on E. coli and S. aureus with maximum zone of growth inhibition of 21mm and 20mm at 200mg/ml respectively Pseudomonas aeruginosa was resistant to both extracts at all the concentrations tested. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) against E. coli for aqueous extract were 50mg/ml and 100mg/ml respectively; and 100mg/ml and 200mg/ml for methanol extract respectively. Similarly, The MIC and MBC against S. aureus for aqueous extract were 100mg/ml and 200mg/ml; 200mg/ml for the methanol extract. Preliminary phytochemical screening reveal the presence of anthraquinones, saponins and tannins in both aqueous and methanol extracts; triterpenes, flavonoids and glycosides were found only in the aqueous extract while alkaloids were found only in the methanol extract. However, carbohydrate and steroids were absent in both extracts. The spectra of activities shown by the extracts could be attributed to the presence of these phytochemicals which signifies the potential of I. asarifolia as a source of therapeutic agents. These findings therefore, justify the traditional medicinal use of the plant.Keywords: Ipomoea asarifolia, phytochemical, antibacterial potency, bacterial pathogensNigerian Journal of Basic and Applied Science (2011), 19 (2): 236-24