Increased development in Canadas northern environments has increased the need for accurate methods to detect adverse impacts on tundra ecosystems. Ammonium nitrate is a common water pollutant associated with many industrial and municipal activities, including diamond mining, and is of special concern due to the toxicity of ammonia in aquatic systems. One solution to reduce exposure of sensitive aquatic systems to nitrogenous compounds is to atomize (atmospherically disperse in fine particles) contaminated water over the arctic tundra which will reduce N loading to surface water. However, the toxicity of ammonium nitrate to arctic soils is poorly understood. In this study I investigate the potential toxicity of ammonium nitrate solutions to arctic soil functions such as carbon mineralization, nitrification and plant growth, to determine concentrations that can be applied without causing significant inhibition to these processes. <p>Arctic ecosystems are based on a soil type termed a cryosol that has an underlying permafrost layer. Often these soils are subject to cryoturbation, a process which heaves and mixes the soil, bringing the mineral horizons to the surface. I hypothesized that phytotoxicity test results in arctic soils would be highly variable compared to other terrestrial ecosystems due to the cryoturbation process and subsequent range of soil characteristics. The variability associated with phytotoxicity tests was evaluated using Environment Canadas standardized plant toxicity test in three cryoturbated soils from Canadas arctic exposed to a reference toxicant, boric acid. The phytotoxicity of boric acid to northern wheatgrass (<i>Elymus lanceolatus </i>) in cryosols was much greater than commonly reported in other soils, with less than 150 ug boric acid g-1 soil needed to inhibit root and shoot growth by 20%. There was also large variability in the phytotoxicity test results, with coefficients of variation for 10 samples ranging from 160 to 79%. Due to this variability in cryoturbated arctic soils, more than 30 samples should be collected from each control and potentially impacted area to accurately assess contaminant effects, and ensure that false negatives of toxicant impacts in arctic soils are minimized. <p>To characterize the toxicity of ammonium nitrate I exposed a variety of arctic soils and a temperate soil to different concentrations of ammonium nitrate solution over a 90 day time period. Dose responses of carbon mineralization, nitrification and phytotoxicity test parameters were estimated for ammonium nitrate applications. In addition to direct toxicity, the effect of ammonium nitrate on ecosystem resistance was investigated by dosing nitrogen impacted soils with boric acid. Ammonium nitrate solutions had no effect on carbon mineralization activity, and affected nitrification rates in only one soil, a polar desert soil from Cornwallis Island. In contrast, ammonium nitrate applications (43 mmol N L-1 soil water) significantly impaired seedling emergence, root length and shoot length of northern wheatgrass. Concentrations of ammonium nitrate in soil water that inhibited plant parameters by 20% varied between 43 to 280 mmol N L-1 soil water, which corresponds with 2,100 to 15,801 mg L-1 in the application water. Arctic soils were more resistant to ammonium nitrate toxicity than the temperate soil under these study conditions. However, it is not clear if this represents a general trend for all polar soils, and because nitrogen is an essential macro-nutrient, nitrogenous toxicity should likely be considered a special case for soil toxicity. As soil concentrations could be maintained under inhibitory levels with continual application of low concentrations of ammonium nitrate over the growing season, atomization of wastewater contaminated with ammonium nitrate is a promising technology for mitigation of nitrogen pollution in polar environments. <p>Increased development in Canadas northern environments has increased the need for accurate methods to detect adverse impacts on tundra ecosystems. Ammonium nitrate is a common water pollutant associated with many industrial and municipal activities, including diamond mining, and is of special concern due to the toxicity of ammonia in aquatic systems. One solution to reduce exposure of sensitive aquatic systems to nitrogenous compounds is to atomize (atmospherically disperse in fine particles) contaminated water over the arctic tundra which will reduce N loading to surface water. However, the toxicity of ammonium nitrate to arctic soils is poorly understood. In this study I investigate the potential toxicity of ammonium nitrate solutions to arctic soil functions such as carbon mineralization, nitrification and plant growth, to determine concentrations that can be applied without causing significant inhibition to these processes. <p>Arctic ecosystems are based on a soil type termed a cryosol that has an underlying permafrost layer. Often these soils are subject to cryoturbation, a process which heaves and mixes the soil, bringing the mineral horizons to the surface. I hypothesized that phytotoxicity test results in arctic soils would be highly variable compared to other terrestrial ecosystems due to the cryoturbation process and subsequent range of soil characteristics. The variability associated with phytotoxicity tests was evaluated using Environment Canadas standardized plant toxicity test in three cryoturbated soils from Canadas arctic exposed to a reference toxicant, boric acid. The phytotoxicity of boric acid to northern wheatgrass (<i>Elymus lanceolatus </i>) in cryosols was much greater than commonly reported in other soils, with less than 150 ug boric acid g-1 soil needed to inhibit root and shoot growth by 20%. There was also large variability in the phytotoxicity test results, with coefficients of variation for 10 samples ranging from 160 to 79%. Due to this variability in cryoturbated arctic soils, more than 30 samples should be collected from each control and potentially impacted area to accurately assess contaminant effects, and ensure that false negatives of toxicant impacts in arctic soils are minimized. <p>To characterize the toxicity of ammonium nitrate I exposed a variety of arctic soils and a temperate soil to different concentrations of ammonium nitrate solution over a 90 day time period. Dose responses of carbon mineralization, nitrification and phytotoxicity test parameters were estimated for ammonium nitrate applications. In addition to direct toxicity, the effect of ammonium nitrate on ecosystem resistance was investigated by dosing nitrogen impacted soils with boric acid. Ammonium nitrate solutions had no effect on carbon mineralization activity, and affected nitrification rates in only one soil, a polar desert soil from Cornwallis Island. In contrast, ammonium nitrate applications (43 mmol N L-1 soil water) significantly impaired seedling emergence, root length and shoot length of northern wheatgrass. Concentrations of ammonium nitrate in soil water that inhibited plant parameters by 20% varied between 43 to 280 mmol N L-1 soil water, which corresponds with 2,100 to 15,801 mg L-1 in the application water. Arctic soils were more resistant to ammonium nitrate toxicity than the temperate soil under these study conditions. However, it is not clear if this represents a general trend for all polar soils, and because nitrogen is an essential macro-nutrient, nitrogenous toxicity should likely be considered a special case for soil toxicity. As soil concentrations could be maintained under inhibitory levels with continual application of low concentrations of ammonium nitrate over the growing season, atomization of wastewater contaminated with ammonium nitrate is a promising technology for mitigation of nitrogen pollution in polar environments.

Increased development in Canadas northern environments has increased the need for accurate methods to detect adverse impacts on tundra ecosystems. Ammonium nitrate is a common water pollutant associated with many industrial and municipal activities, including diamond mining, and is of special concern due to the toxicity of ammonia in aquatic systems. One solution to reduce exposure of sensitive aquatic systems to nitrogenous compounds is to atomize (atmospherically disperse in fine particles) contaminated water over the arctic tundra which will reduce N loading to surface water. However, the toxicity of ammonium nitrate to arctic soils is poorly understood. In this study I investigate the potential toxicity of ammonium nitrate solutions to arctic soil functions such as carbon mineralization, nitrification and plant growth, to determine concentrations that can be applied without causing significant inhibition to these processes. <p>Arctic ecosystems are based on a soil type termed a cryosol that has an underlying permafrost layer. Often these soils are subject to cryoturbation, a process which heaves and mixes the soil, bringing the mineral horizons to the surface. I hypothesized that phytotoxicity test results in arctic soils would be highly variable compared to other terrestrial ecosystems due to the cryoturbation process and subsequent range of soil characteristics. The variability associated with phytotoxicity tests was evaluated using Environment Canadas standardized plant toxicity test in three cryoturbated soils from Canadas arctic exposed to a reference toxicant, boric acid. The phytotoxicity of boric acid to northern wheatgrass (<i>Elymus lanceolatus </i>) in cryosols was much greater than commonly reported in other soils, with less than 150 ug boric acid g-1 soil needed to inhibit root and shoot growth by 20%. There was also large variability in the phytotoxicity test results, with coefficients of variation for 10 samples ranging from 160 to 79%. Due to this variability in cryoturbated arctic soils, more than 30 samples should be collected from each control and potentially impacted area to accurately assess contaminant effects, and ensure that false negatives of toxicant impacts in arctic soils are minimized. <p>To characterize the toxicity of ammonium nitrate I exposed a variety of arctic soils and a temperate soil to different concentrations of ammonium nitrate solution over a 90 day time period. Dose responses of carbon mineralization, nitrification and phytotoxicity test parameters were estimated for ammonium nitrate applications. In addition to direct toxicity, the effect of ammonium nitrate on ecosystem resistance was investigated by dosing nitrogen impacted soils with boric acid. Ammonium nitrate solutions had no effect on carbon mineralization activity, and affected nitrification rates in only one soil, a polar desert soil from Cornwallis Island. In contrast, ammonium nitrate applications (43 mmol N L-1 soil water) significantly impaired seedling emergence, root length and shoot length of northern wheatgrass. Concentrations of ammonium nitrate in soil water that inhibited plant parameters by 20% varied between 43 to 280 mmol N L-1 soil water, which corresponds with 2,100 to 15,801 mg L-1 in the application water. Arctic soils were more resistant to ammonium nitrate toxicity than the temperate soil under these study conditions. However, it is not clear if this represents a general trend for all polar soils, and because nitrogen is an essential macro-nutrient, nitrogenous toxicity should likely be considered a special case for soil toxicity. As soil concentrations could be maintained under inhibitory levels with continual application of low concentrations of ammonium nitrate over the growing season, atomization of wastewater contaminated with ammonium nitrate is a promising technology for mitigation of nitrogen pollution in polar environments. <p>Increased development in Canadas northern environments has increased the need for accurate methods to detect adverse impacts on tundra ecosystems. Ammonium nitrate is a common water pollutant associated with many industrial and municipal activities, including diamond mining, and is of special concern due to the toxicity of ammonia in aquatic systems. One solution to reduce exposure of sensitive aquatic systems to nitrogenous compounds is to atomize (atmospherically disperse in fine particles) contaminated water over the arctic tundra which will reduce N loading to surface water. However, the toxicity of ammonium nitrate to arctic soils is poorly understood. In this study I investigate the potential toxicity of ammonium nitrate solutions to arctic soil functions such as carbon mineralization, nitrification and plant growth, to determine concentrations that can be applied without causing significant inhibition to these processes. <p>Arctic ecosystems are based on a soil type termed a cryosol that has an underlying permafrost layer. Often these soils are subject to cryoturbation, a process which heaves and mixes the soil, bringing the mineral horizons to the surface. I hypothesized that phytotoxicity test results in arctic soils would be highly variable compared to other terrestrial ecosystems due to the cryoturbation process and subsequent range of soil characteristics. The variability associated with phytotoxicity tests was evaluated using Environment Canadas standardized plant toxicity test in three cryoturbated soils from Canadas arctic exposed to a reference toxicant, boric acid. The phytotoxicity of boric acid to northern wheatgrass (<i>Elymus lanceolatus </i>) in cryosols was much greater than commonly reported in other soils, with less than 150 ug boric acid g-1 soil needed to inhibit root and shoot growth by 20%. There was also large variability in the phytotoxicity test results, with coefficients of variation for 10 samples ranging from 160 to 79%. Due to this variability in cryoturbated arctic soils, more than 30 samples should be collected from each control and potentially impacted area to accurately assess contaminant effects, and ensure that false negatives of toxicant impacts in arctic soils are minimized. <p>To characterize the toxicity of ammonium nitrate I exposed a variety of arctic soils and a temperate soil to different concentrations of ammonium nitrate solution over a 90 day time period. Dose responses of carbon mineralization, nitrification and phytotoxicity test parameters were estimated for ammonium nitrate applications. In addition to direct toxicity, the effect of ammonium nitrate on ecosystem resistance was investigated by dosing nitrogen impacted soils with boric acid. Ammonium nitrate solutions had no effect on carbon mineralization activity, and affected nitrification rates in only one soil, a polar desert soil from Cornwallis Island. In contrast, ammonium nitrate applications (43 mmol N L-1 soil water) significantly impaired seedling emergence, root length and shoot length of northern wheatgrass. Concentrations of ammonium nitrate in soil water that inhibited plant parameters by 20% varied between 43 to 280 mmol N L-1 soil water, which corresponds with 2,100 to 15,801 mg L-1 in the application water. Arctic soils were more resistant to ammonium nitrate toxicity than the temperate soil under these study conditions. However, it is not clear if this represents a general trend for all polar soils, and because nitrogen is an essential macro-nutrient, nitrogenous toxicity should likely be considered a special case for soil toxicity. As soil concentrations could be maintained under inhibitory levels with continual application of low concentrations of ammonium nitrate over the growing season, atomization of wastewater contaminated with ammonium nitrate is a promising technology for mitigation of nitrogen pollution in polar environments.

Scope and contents: An investigation into some arctic soils located on Southwest Devon Island. Some aspects of chemical weathering in the area are considered and detailed studies of patterned ground are undertaken. A terrain map was compiled to locate the major areas of soils and mineral and organic covers and to show this relationship to relief units. / No abstract provided. / Thesis / Master of Science (MSc)

In recent years, concern has grown over the consequences of global warming. The arctic region is thought to be particularly vulnerable to increasing temperatures, and warming is occurring here substantially more rapidly than at lower latitudes. Consequently, assessments of the state of the Arctic are a focus of international efforts. For the terrestrial Arctic, large datasets are generated by remote sensing of above-ground variables, with an emphasis on vegetation properties, and, by association, carbon fluxes. However, the terrestrial component of the carbon (C) cycle remains poorly quantified and the below-ground distribution and stocks of soil C can not be quantified directly by remote sensing. Large areas of the Arctic are also difficult to access, limiting field surveys. The scientific community does know, however, that this region stores a massive proportion (although poorly quantified, soil C stocks for tundra soils vary from 96 to 192 Gt C) of the global reservoir of soil carbon, much of it in permafrost (900 Gt C), and these stocks may be very vulnerable to increased rates of decomposition due to rising temperatures. The consequences of this could be increasing source strength of the radiatively forcing gases carbon dioxide (CO2) and methane (CH4). The principal objective of this project is to provide a critical evaluation of methods used to link soil C stocks and fluxes at the usual scales spanned by the field surveys (centimetre to kilometre) and remote sensing surveys (kilometre to hundreds of kilometres). The soil C distribution of two sub-arctic sites in contrasting climatic, landscape/geomorphologic and vegetation settings has been described and analysed. The transition between birch forest and tundra heath in the Abisko (Swedish Lapland) field site, and the transition between mire and birch forest in the Kevo (Finnish Lapland) field site span several vegetation categories and landscape contexts. The natural variability of below-ground C stocks (excluding coarse roots > 2 mm diameter), at scales from the centimetre to the kilometre scale, is high: 0.01 to 18.8 kg C m-2 for the 0 - 4 cm depth in a 2.5 km2 area of Abisko. The depths of the soil profiles and the soil C stocks are not directly linked to either vegetation categories or Leaf Area Index (LAI), thus vegetation properties are not a straightforward proxy for soil C distribution. When mapping soil or vegetation categories over large areas, it is usually necessary to aggregate several vegetation or soil categories to simplify the output (both for mapping and for modelling). Using this approach, an average value of 2.3 kg C m-2 was derived both for soils beneath treeless areas and forest understorey. This aggregated value is potentially misleading, however, because there is significant skew resulting from the inclusion of exposed ridges (with very low soil C stocks) in the ‘treeless’ category. Furthermore, if birch trees colonise tundra heath and other ‘open’ plant communities in the coming decades, there will likely be substantial shifts in soil C stocks. This will be both due to direct climate effects on decomposition, but also due to changes in above- and below-ground C inputs (both in quantity and quality) and possibly changes in so-called root ‘priming’ effects on the decomposition of existing organic matter. A model of soil respiration using parameters from field surveys shows that soils of the birch forest are more sensitive to increases in mean annual temperature than soils under tundra heath. The heterogeneity of soil properties, moisture and temperature regimes and vegetation cover in ecotone areas means that responses to climate change will differ across these landscapes. Any exercise in upscaling results from field surveys has to indicate the heterogeneity of vegetation and soil categories to guide soil sampling and modelling of C cycle processes in the Arctic.