Sediment nitrogen Subject

Lee, R. Y., Joye, S. B., Roberts, B. J., and Valiela, I. (1997). Release ofN2 andN20 from salt-marsh sediments subject to different land-derived nitrogen loads. Biol. Bull. 193, 292—293. 

Stand both natural and anthropogenic sediments. Conventional soil analysis techniques include a mixture of subjective field designations combined with relatively simple quantitative laboratory tests for important major elements such as carbon, calcium, nitrogen, phosphorus, aluminum, and iron (J,2). 

Nitrogen may exist as dissolved N2 in equilibrium with ammonium ion at Eh and pH levels encountered in natural environments. This subject should be investigated further, as the occurrence of dissolved N2 could explain losses in N-budgets, and necessitate special precautions in the treatment of sediment samples (in order to avoid significant losses of N2). 

The contribution of anaerobic ammonium oxidation reaction to overall nitrogen loss in wetlands and aquatic systems has been a subject to great speculation. The significance of this process has been demonstrated in marine systems, but to our knowledge there is no reported documentation in freshwater systems. Anaerobic ammonium oxidizers are obligate anaerobes and it is likely their activity can be promoted by other inorganic electron acceptors such as iron and manganese oxides and sulfates. However, there is no reported evidence that these reactions occur in wetland soils and aquatic sediments. 

A subject of increasing importance has been the composition of oceanic particulate matter and the sediments derived from it. While the concentrations of organic carbon and nitrogen are much lower per unit volume than in the dissolved phase, the ability to concentrate the particle load by some form of filtration or centrifugation should result in the production of samples within the range of commercial CHN analyzers. Accordingly, we would expect a better performance from laboratories in an intercomparison test for particulate organic... 

An MIP adsorbent is prepared for the extraction of 7-diethylamino-4-methyl-coumarin (Fig. 3). The print molecule, 7-diethylamino-4-methylcoumarin (4 mmol, 0.925 g), a functional monomer, 2-(trifluoromethyl) acrylic acid (12 mmol, 1.681 g), a cross-linking monomer, ethylene glycol dimethacrylate (60 mmol, 11.893 g) and a polymerization initiator, 2,2 -azobis(2,4-dimethylvaleronitrile) (0.140 g) are dissolved in anhydrous toluene (18 mL) in a 50-mL borosilicate PYREX tube.The solution is briefly purged with dry nitrogen for 5 min and sealed with a screw cap. The PYREX tube is transferred to a water bath preset at 45°C and maintained for 16 h. After polymerization, the polymer monolith is taken from the PYREX tube and fractured. This is further ground with a mechanical mortar (Retsch, Haan, ERG) and wet-sieved with 5% ethanol (v/v), and subjected to repetitive sedimentation in... 

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