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This study examined the impact of active layer detachments (ALDs) on seasonal dissolved nitrogen (N) export from continuous permafrost headwater catchments at the Cape Bounty Arctic Watershed Observatory (CBAWO), Melville Island, Nunavut. Runoff samples collected throughout the summer of 2012 from an undisturbed catchment (Goose; GS) and from one that was disturbed by ALDs (Ptarmigan; PT) were analyzed for dissolved inorganic ions and species of total dissolved N (TDN), including dissolved organic N (DON) and dissolved inorganic N (DIN; ammonium (NH4+), nitrite (NO2-), and nitrate (NO3-)). Rainfall samples were also collected for dissolved ions analyses. Select runoff and rainfall samples were analyzed for stable isotopes of nitrogen and oxygen in NO3- (δ15N-NO3- and δ18O-NO3-, respectively) to determine its origin streamwater. Data from 2012 were compared to predisturbance data to assess the long-term effects of ALDs on N export. ALDs increased the proportion of DIN/TDN in PT from 4% (predisturbance) to 37% in 2012. The increase in DIN/TDN in PT largely resulted from significantly higher NO3- in runoff. Values of δ18O and δ15N-NO3- as well as correlations between NO3- and major ions indicated that the higher NO3- in PT was due to the exposure of mineral soils in ALDs, which likely reduced NO3- sinks (e.g. plant uptake) and increased inputs of nitrified-NO3-. Values of δ18O-NO3- during initial runoff showed that NO3- supplied from the snowpack overwhelmed NO3- sinks in PT, leading to a twelve-fold higher peak NO3- concentration relative to GS. Low δ18O-NO3- values in runoff during stormflow indicated that inputs of DIN from rainfall (1545 ± 148 and 1838 ± 174 g N-DIN to GS and PT, respectively) supplied less than 30% of the NO3- in both streams, and that exceptionally high NO3- concentrations in PT resulted from flushing of mineralized-NO3- from the mineral soils. Seasonal DIN flux was 95% higher in PT relative to GS, because NO3- export from PT was 27 times that of GS. This is the first study to show that ALDs can have persistent impacts on DIN export from High Arctic watersheds, and that this results from enhanced export of mineralized-NO3-. / Thesis (Master, Geography) -- Queen's University, 2014-05-27 10:30:38.874

Field scale variability of soil texture can influence crop yield and movement of soil water in the field. The objective of this study was to investigate the spatial structure of soil texture in relation to the variability of nitrate-N leaching using geostatistics. Soil textural fractions showed strong spatial autocorrelations from surface to 60 cm depth. Random variability of soil texture increased with depth. Soil water content, as well as total carbon, total nitrogen and soil organic carbon of top 15 cm, also showed spatial autocorrelations similar to soil texture. Elevation, relative slope position and vertical distance to channel network showed significant influence on the distribution of soil texture. Soil texture at 90 cm depth correlated best with cumulative percolated water and cumulative nitrate leached in field lysimeters. Our results showed that soil layers with low hydraulic conductivity control the water and nitrate movement through the soil profile.

Nitrogen fertilizer use suffers from low efficiencies and increased residual NO$ sb3$ in the soil. The purpose of this study was to compare N fertilizer efficiency by a comparison of three N sources, three rates of N fertilization, and three application times of N fertilizer. Grain corn yields increased with increases in N rates, and split applications of N were superior to preplant incorporated (PPI) fertilizer. Grain N uptake was associated to grain yield and N uptake. Stover yields increased with increased N and varied with application times of N, but the effects were not as pronounced as with grain yields. Soil NO$ sb3$ generally increased with increases of added N but not with split application of N compared to PPI N. Soil NO$ sb3$ in the spring in control plots was related to grain yield response to added N but not to stover yield response.

Zugl.: Hannover, Univ., Diss., 2007

Thesis (Ph. D.)--Auburn University. / Abstract. Vita. Includes bibliographical references (p. 73-80).

Thesis (Ph. D.)--University of Illinois. / "Biographical": 1 p. at end. "Under the title 'The ionization and hydration relations of electrolytes in aqueous solution at zero degrees: A. Cesium nitrate, potassium chloride and lithium chloride, ' this thesis was published in the J. Am. Chem. Soc., 33, 1686-1713 (1911) as the third article in a series entitled, 'The laws of "concentrated" solutions'": p. [3].

Thesis (Ph. D.)--University of Illinois. / "Biographical": 1 p. at end. "Under the title 'The ionization and hydration relations of electrolytes in aqueous solution at zero degrees: A. Cesium nitrate, potassium chloride and lithium chloride, ' this thesis was published in the J. Am. Chem. Soc., 33, 1686-1713 (1911) as the third article in a series entitled, 'The laws of "concentrated" solutions'": p. [3].

Inaug.-Diss.--Königsberg.