Nitrate contamination of water is a worldwide issue. Nitrate is especially dangerous for young children, and may result in potentially fatal blue baby syndrome when concentration in drinking water is > 10 mg/L N-NO3. Nitrate in surface water may also lead to eutrophication. Sources of NO3- contamination include nitrate fertilizers, wastewater treatment plants, individual domestic septic systems, runoff from animal feedlots, and natural soil nitrogen. Nitrate contamination in the Elbe River drainage, covering 148,270 km2 in Germany and the Czech Republic, has been a long-term issue. This study examines the upper one-third of the basin, located almost entirely in the Czech Republic. In the Czech Republic, NO3- concentrations, which in some river reaches exceed the European Union (EU) standard of 50 mg/L, have decreased only slightly or remained constant since monitoring began in the 1960's. At the German border the calculated average 2000-2008 Elbe discharge is 9.4 x 109 m3/yr and annual NO3- loading is 37.4 x 106 kg/yr. The upper Elbe has four major tributaries: the Labe (Elbe), Berounka, Ohře, and Vltava whose percentages of total discharge and NO3- loading are 10.3/10.4, 28.0/33.3, 12.6/8.9, and 49.1/47.4 percent, respectively. Flow and NO3- concentrations for 138 locations were obtained from the Czech Hydrometeorological Institute. δ15N compositions, determined for 57 locations, were used to create a map showing the estimated spatial distribution of nitrate sources within the basin. Nitrate loading for each sample site was calculated using historical concentration and flow data for 2000-2008. Preliminary calculations suggest that ~ 76 percent of the nitrate load is from human/animal waste. Given that large feedlot operations are rare, the major source of nitrate in the region is likely small wastewater treatment plants and rural septic systems.

Thesis advisor: Noah P. Snyder / Nitrogen is an important component in the biogeochemical processes of freshwater systems. Likewise, it is unknown if, and to what magnitude, changes in land use in the watersheds of New England lakes have affected nitrogen availability. This study examines the effects of land-use change on the present and historic isotopic signatures of nitrogen in three New England lakes of varied histories, Lower South Branch Pond, Little Kennebago Lake, and Sennebec Pond. The histories of all three sites indicate minimal discernible disturbance before the onset of Euro-American-induced land use change. For two sites, the dominant mechanism of change was timber harvest, which began in the latter half of the 19th century. Sediment cores for each site were examined and variations in geochemical and sedimentological indicators were evaluated in the context of changes within respective basins. Statistical analysis indicates significant shifts in the means and variance of the geochemistry within the Little Kennebago Lake and Sennebec Pond watersheds after the incursion of Euro-American settlers, while the Lower South Branch Pond watershed displays similarities to a more widespread signal of anthropogenic nitrogen that has been deposited remotely. The record of magnetic susceptibility in Little Kennebago Lake displays the largest variation compared to the other two lakes, which may indicate that the magnitude of land-use change within the basin was more impactful relative to Lower South Branch Pond and Sennebec Pond. This is significant in that all three sites experienced some level of land-clearance. / Thesis (MS) — Boston College, 2023. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Earth and Environmental Sciences.

Yes / Background: There are few reliable osteological indicators to detect parity or infer puberty in skeletal remains. Nitrogen (δ15N) and stable carbon (δ13C) isotope ratios in human tissues can be affected by metabolically unbalanced states engendered by pregnancy or rapid growth, offering potential biomarkers. Aim: This pilot study explores the potential of incremental dentine-collagen isotope ratio analysis to identify puberty and gestation. Methodology: Incremental dentine δ15N and δ13C profiles were produced by analysing third molars extracted as part of dental treatment of 10 individuals living in Sudan. Demographic and anthropometric data at the time of tooth extraction was available. Medical histories were unknown. Results: Isotopic signatures potentially related to pubertal growth, with an average δ15N reduction of 0.78±0.29‰, are indicated. Six isotopic signals suggestive of pregnancy, with an average δ15N decrease of 0.48±0.22‰, are also observed. The timing, speed and amplitude of post-partum δ15N patterns seemingly infer infant feeding practices and maternal nutritional status. Conclusion: This pilot study highlights the potential of incremental dentine isotope analysis for the reconstruction of early reproductive histories in skeletal remains. However, controlled studies with larger human cohort are needed to validate these findings, establish isotopic signals linked to puberty and lactation, and improve chronology accuracy.

A dissertation submitted to the Faculty of Science, University of Witwatersrand, in fulfilment of the requirements for the degree of Masters of Science Johannesburg, 2012. / Amplified loads of sulfate and nitrate have caused increased stress on soil systems in many areas of the world, as both are dominant components of acid rain. This is a critical environmental stress due to the damage caused to soil, water quality and ecosystem functioning. Issues concerning the rising emissions of these elements from local industries have begun to attract increasing attention in South Africa, as the rates of deposition in the Mpumalanga Highveld region alone is comparable to those experienced in First World countries. This study sought to investigate the use of natural stable isotopes of sulfur and nitrogen to identify the process transformations that these species undergo in environmental cycles. Total δ34S, δ15N and δ13C isotope signature of soils in the Mpumalanga region were combined with total elemental concentrations to determine the effect of deposition on the soil system. Soil samples from two soil depths (0 – 10 cm and 20 – 40 cm) were taken along a distance gradient from an identified pollution source, the Majuba power station. Long-term air quality data from the study area were also obtained from Eskom’s air quality monitoring stations, as well as sulfur and nitrogen deposition data from selected literature. Elemental concentrations decreased with soil depth as expected, while sites located approximately 25 km downwind of the power station were seen to contain higher concentrations of both soil sulfur and nitrogen. The mean per site soil sulfur concentration across all depths ranged from 0.009 % to 0.048 %, while the mean per site nitrogen concentration across all depths ranged from 0.056 % to 0.346 %. The mean soil carbon concentration in the top-soils ranged from 0.97 % to 7.93 %, and decreased in the sub-soils to 0.490 % to 3.270 %.The mean δ34S value for the top-soils was found to be 8.28 ‰ and increased to 10.78 ‰ in the sub-soils. Soil δ15N also increased with soil depth from 6.55 ‰ to 8.28 ‰. Soil δ13C values were seen to increase from -12.83 ‰ in the top-soils to -11.90 ‰ in the sub-soils. Lighter δ34S values at the surface may be due to anthropogenic deposition. The positive δ34S shift was attributed to a two-source mixing model (atmospheric deposition and bedrock) and isotopic fractionation processes that occur within the soil profile. The δ15N values of the top-soil were higher than what is expected if all nitrogen was derived from atmospheric nitrogen gas fixation. The increase in δ15N with depth suggested that isotope fractionation occurred during nitrogen export due to the faster reaction rate of 14N compared to 15N. The soil δ13C values indicated a typical C4 grassland system. New carbon at the top-soil depths was enriched in 13C due to the slower decay of 13C-depleted lignin; whereas in the sub-soils microbial recycling of carbon dominates and explained the higher 13C content of the older carbon. The conceptual framework presented for this project involves simultaneous processes of deposition and export in the soil system. This was particularly true for sulfur, where sites with lower isotope values had lower soil sulfur concentrations and vice versa. This indicates that high levels of deposition correspond to high net export. The sulfur and nitrogen isotopic signatures could not be used to as a direct means of source identification; however, the effectiveness of isotopes in elucidating transfer of these nutrients in the soil system was illustrated.

O continente Antártico é considerado um ambiente pouco impactado, porém com o aumento das atividades humanas e do número de estações de pesquisa, há uma tendência de aumento dos níveis de alguns contaminantes. Neste estudo estabeleceram-se os níveis de arsênio, cádmio, chumbo, cobre, cromo, mercúrio, níquel, zinco, e a razão isotópica de nitrogênio, em sedimentos e na biota, coletados em 2003, na Baía do Almirantado, Ilha Rei George, Antártica. Os metais pesados foram quantificados por Espectrometria de Emissão Ótica com Plasma Indutivamente Acoplado (ICP-OES). Os resultados demonstraram elevadas concentrações de cobre e zinco nos sedimentos, atribuídas à composição geológica da região. Verificou-se bioacumulação de arsênio na biota da Baía do Almirantado, e bioacumulação de cádmio e zinco na biota da Enseada Martel. Somente cobre apresentou tendência de biomagnificação na teia trófica estudada. O molusco Laternula elliptica se apresentou como um bom biomonitor das concentrações de metais pesados para o ambiente Antártico. Além disso, os resultados foram úteis para o conhecimento dos níveis de metais pesados nas condições pré-acidente da Estação Antártica Comandante Ferraz (EACF), que ocorreu em 2012, e para comparação com as atuais condições, dentro dos trabalhos de monitoramento que estão sendo realizados pelo INCT-APA (Instituto Nacional de Ciência e Tecnologia Antártico de Pesquisas Ambientais). / The Antarctic continent is considered a slightly affected environment, but as the human activities and the number of research stations are increasing, there is a tendency of a higher level of some contaminants. This study established the levels of arsenic, cadmium, lead, copper, chromium, mercury, nickel, zinc, and nitrogen isotope ratios in sediments and biota collected in 2003, in Almirantado Bay, Rei George Island, Antarctica. Heavy metals were quantified by Optical Emission Spectrometry with Inductively Coupled Plasma (ICP-OES). The results showed high concentrations of copper and zinc in sediments attributed to the geological composition of the region. There was arsenic bioaccumulation in biota of Almirantado Bay, and bioaccumulation of cadmium and zinc in the biota of Martel Bay. Only copper tended to biomagnification in the trophic web studied. The clam Laternula elliptica presented itself as a good biomonitor of heavy concentrations of metals for Antarctic environment. Moreover, the results were useful for the acknowledge of the levels of heavy metals in pre-accident conditions of Comandante Ferraz Antarctic Station (EACF), which occurred in 2012, and for comparison with current conditions within the monitoring work now performed by INCT-APA (National Antartic Institute of Science and Technology Environmental Research).

Cellulose-inferred lake water oxygen-isotope records were obtained from five throughflow lakes situated along a north-south transect across Fennoscandia to help develop a better picture of Holocene changes in atmospheric circulation in the region. This research addresses prior evidence for the existence of non-temperature-dependent shifts in d18O of precipitation in the early Holocene attributed to changes in atmospheric circulation. The validity of this hypothesis is tested through the development of oxygen-isotope records from lake sediments and their interpretation in the context of independent reconstructions of temperature and precipitation from pollen and chironomid head-capsules collected from the same or nearby sites, and well-documented changes in vegetation composition. Records of carbon and nitrogen elemental content and isotopic composition and magnetic susceptibility are included in this multi-proxy investigation. Extensive modern isotope hydrology datasets spanning several years at four of the five sites also help to inform interpretations of the cellulose d18O records. Key results from this research are: 1) Elevated d18O in relation to prevailing temperature occurred during the early Holocene (c. 10,000-6000 cal. BP) for sites in northern Fennoscandia (Lake Tibetanus, Lake Spåime), in harmony with previous interpretations suggesting that strong zonal atmospheric circulation led to deepening of the precipitation and isotope shadows in the lee of the Scandes Mountains. 2) Evidence from a southern site (Arbovatten) reveals a previously unrecognized negative offset in the d18O-temperature relation during the early Holocene, apparently transferred directly from the North Atlantic without the orographic effects associated with a topographic barrier. 3) The modern d18O-temperature relation appears to have been established throughout Fennoscandia by c. 6000-4000 cal. BP, probably due to generally weaker circumpolar atmospheric circulation in response to lower summer insolation. 4) Comparison of two sites (Lake Spåime, Svartkälstjärn) in a west-east transect across central Fennoscandia reveals higher-frequency variability in atmospheric circulation at submillennial scales throughout the Holocene, which appears to be analogous to contemporary variability in the North Atlantic Oscillation (NAO) at seasonal-to-decadal time-scales. Evidence of such NAO-like variability also exists at two northern sites (Lake Keitjoru, Oikojärvi) during the Holocene, likely reflecting variations in summer and winter atmospheric circulation. 5) Complex lake-specific changes in productivity occurred in response to Holocene climate change, as revealed by carbon and nitrogen elemental and isotopic data in lake sediments. A major shift in atmospheric circulation pattern occurring at c. 4000 cal. BP probably led to a reduction in soil-derived 13C-depleted nutrients in five lakes (Lake Keitjoru, Oikojärvi, Lake Spåime, Svartkälstjärn, Arbovatten) associated with changes in terrestrial vegetation. Changes in sediment nitrogen isotope composition also occurred in these lakes at c. 4000 cal. BP, possibly reflecting changing nutrient supply dynamics because of enhanced nitrogen losses during spring snowmelt.

Cellulose-inferred lake water oxygen-isotope records were obtained from five throughflow lakes situated along a north-south transect across Fennoscandia to help develop a better picture of Holocene changes in atmospheric circulation in the region. This research addresses prior evidence for the existence of non-temperature-dependent shifts in d18O of precipitation in the early Holocene attributed to changes in atmospheric circulation. The validity of this hypothesis is tested through the development of oxygen-isotope records from lake sediments and their interpretation in the context of independent reconstructions of temperature and precipitation from pollen and chironomid head-capsules collected from the same or nearby sites, and well-documented changes in vegetation composition. Records of carbon and nitrogen elemental content and isotopic composition and magnetic susceptibility are included in this multi-proxy investigation. Extensive modern isotope hydrology datasets spanning several years at four of the five sites also help to inform interpretations of the cellulose d18O records. Key results from this research are: 1) Elevated d18O in relation to prevailing temperature occurred during the early Holocene (c. 10,000-6000 cal. BP) for sites in northern Fennoscandia (Lake Tibetanus, Lake Spåime), in harmony with previous interpretations suggesting that strong zonal atmospheric circulation led to deepening of the precipitation and isotope shadows in the lee of the Scandes Mountains. 2) Evidence from a southern site (Arbovatten) reveals a previously unrecognized negative offset in the d18O-temperature relation during the early Holocene, apparently transferred directly from the North Atlantic without the orographic effects associated with a topographic barrier. 3) The modern d18O-temperature relation appears to have been established throughout Fennoscandia by c. 6000-4000 cal. BP, probably due to generally weaker circumpolar atmospheric circulation in response to lower summer insolation. 4) Comparison of two sites (Lake Spåime, Svartkälstjärn) in a west-east transect across central Fennoscandia reveals higher-frequency variability in atmospheric circulation at submillennial scales throughout the Holocene, which appears to be analogous to contemporary variability in the North Atlantic Oscillation (NAO) at seasonal-to-decadal time-scales. Evidence of such NAO-like variability also exists at two northern sites (Lake Keitjoru, Oikojärvi) during the Holocene, likely reflecting variations in summer and winter atmospheric circulation. 5) Complex lake-specific changes in productivity occurred in response to Holocene climate change, as revealed by carbon and nitrogen elemental and isotopic data in lake sediments. A major shift in atmospheric circulation pattern occurring at c. 4000 cal. BP probably led to a reduction in soil-derived 13C-depleted nutrients in five lakes (Lake Keitjoru, Oikojärvi, Lake Spåime, Svartkälstjärn, Arbovatten) associated with changes in terrestrial vegetation. Changes in sediment nitrogen isotope composition also occurred in these lakes at c. 4000 cal. BP, possibly reflecting changing nutrient supply dynamics because of enhanced nitrogen losses during spring snowmelt.

Recent paleolimnological research in the eastern Canadian high Arctic on the ecological impact of the Thule c.1000-1500 AD has documented the influence of prehistoric anthropogenic activities. Six lake and pond sites (three pairs) on the south-western coast of Baffin Island, Nunavut, were used to compare impacted and non-impacted sites in the southern-most region of Thule occupation, as well as to compare Thule occupation sites with sites occupied by another early Arctic population group, the Dorset. Tanfield 1 and Tanfield 2 (impacted and control, respectively) are adjacent to several multiple-occupation Dorset sites on Cape Tanfield; Juet 1 and 2 (impacted and control, respectively) are adjacent to a short-term occupation Dorset site on Juet Island; McKellar 1 is adjacent to a multiple-occupation Thule site near McKellar Bay. A nearby site (McKellar 2) was also studied, but it was clearly an anomalous, eutrophic site, rather than a control for McKellar 1. Diatom assemblages and sedimentary 15N profiles were analyzed in sediment cores from all study sites. Selected paired sediment intervals were AMS radiocarbon dated using both humic acids and terrestrial macrofossils in an attempt to establish basal dates for each core. Significant differences between several of the paired AMS radiocarbon dates serve as a cautionary note for dating Arctic sediments using either humic acids or terrestrial macrofossils. Paleolimnological analyses revealed that at both multiple-occupation sites (Tanfield 1 and McKellar 1), the activities of the Dorset and the Thule influenced lake ecology, while at the short-term occupation site (Juet 1), the Dorset occupation was not sufficiently large to have a discernible impact. McKellar 1 showed a greater impact compared to Tanfield 1, consistent with the intense marine mammal hunting by Thule at the former, compared to the moderate marine mammal hunting by Dorset at Tanfield 1. The origin of marine-derived nutrients at McKellar 2 could not be ascertained with certainty. The influence of early Arctic population groups remains obvious in present-day nutrient- and production-related water chemistry variables. This research points to the value of collaborations between paleolimnologists and archaeologists and may provide insight into the future implications of current anthropogenic activities in the Arctic. / Thesis (Master, Biology) -- Queen's University, 2011-10-04 15:52:18.29

The western Antarctic Peninsula (WAP) is a hotspot of climatic and oceanographic change, with a 6°C rise in winter atmospheric temperatures and >1°C warming of the surface ocean since the 1950s. These trends are having a profound impact on the physical environment at the WAP, with widespread glacial retreat, a 40% decline in sea ice coverage and intensification of deep water upwelling. The main objective of this study is to assess the response of phytoplankton productivity to these changes, and implications for the marine carbon and nitrogen cycles in the WAP coastal zone. An extensive suite of biogeochemical and physical oceanographic data was collected over five austral summer growing seasons in northern Marguerite Bay between 2004 and 2010. Concentrations and isotopic compositions ( 15N, 13C, 14C) of dissolved nitrate, dissolved inorganic carbon species, particulate nitrogen, organic carbon and chlorophyll a are used in the context of a substantial ancillary dataset to investigate nutrient supply, phytoplankton productivity and nutrient uptake, export flux and the fate of organic material, and the factors underpinning pronounced seasonal and interannual variability. High-resolution biogeochemical time-series data for surface and underlying seawater, sea ice brine, sediment trap material and coretop sediments allow detailed examination of carbon and nitrogen cycle processes under contrasting oceanographic conditions and the interaction between these marine processes and air-sea exchange of climate-relevant CO2. This study shows that the WAP marine environment is currently a summertime sink for atmospheric CO2 in most years due to high productivity and biological carbon uptake sufficient to offset the CO2 supply from circumpolar deep waters, which act as a persistent source of heat, nutrients and CO2 across the shelf. For the first time, CO2 sink/source behaviour is parameterised in terms of nitrate utilisation, by exploiting the relationship between CO2 and nitrate concentrations, and deriving the nitrate depletion at which surface ocean CO2 is undersaturated relative to atmosphere and carbon sink behaviour is achieved. This could have vast utility in examining CO2 sink/source dynamics over greater spatial and temporal scales than by direct CO2 measurements, of which availability is more limited. This study documents abrupt changes in phytoplankton productivity, nitrate utilisation and biological CO2 uptake during a period of rapid sea ice decline. In fact, nitrate utilisation, particulate organic matter production and biological CO2 uptake all decrease by at least 50 % between a sea ice-influenced, high productivity season and one of low sea ice and low productivity. The key driver of interannual variability in production and export of organic material is found to be upper ocean stratification and its regulation of light availability to phytoplankton. Productivity, CO2 uptake and export are maximal when stratification is sufficient to provide a stable well-lit surface environment for phytoplankton growth, but with some degree of mixing to promote export of suspended organic matter. Strong stratification causes intense initial production, but retention of suspended organic particles in the surface ocean induces a self-shading effect, and overall productivity, CO2 uptake and export fluxes are low. When stratification is weak, mixing of phytoplankton over a larger depth range exposes cells to a wider range of light levels and reduces photosynthetic efficiency, thus total productivity and CO2 uptake. A conceptual model is developed here, which attempts to describe the mechanism by which sea ice dynamics exert the principal control on stratification and therefore productivity and CO2 uptake at the WAP, with potential application to other regions of the Antarctic continental shelf. Although meteoric waters (glacial melt and precipitation) are more prevalent in surface waters throughout the study, sea ice meltwater variability is driven by large and rapid spring/early summer pulses, which stabilise the upper ocean and initiate phytoplankton growth. The timing and magnitude of these sea ice melt pulses then exert the key control on stratification and seasonal productivity. In a low sea ice year of this study, the sea ice trigger mechanism was absent and productivity was low. This strongly suggests that ongoing sea ice decline at the WAP and greater frequency of such low sea ice years is likely to drive a dramatic reduction in productivity and export, which would substantially reduce the capacity of the summertime CO2 sink in this region. Ongoing warming and ecosystem change are thus likely to have severe impacts on net CO2 sink/source behaviour at the WAP over the annual cycle, and the role of the Southern Ocean in regulating atmospheric CO2 and global climate. Finally, factors influencing the stable isotopic signature of particulate organic carbon ( 13CPOC), a common paleo-proxy, are assessed. 13CPOC is greatly influenced by seasonal shifts in diatom assemblages and isotopically heavy sea ice material, so cannot be used as a robust proxy for ambient CO2 in the coastal Southern Ocean.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniversitet, 2005. / Härtill 4 uppsatser.