Diffuse agricultural pollution is a major contributor to poor water quality in many parts of the world. Consequently agri-environment policy promotes the use of riparian buffer strips and/or denitrifying wetlands to intercept and remove diffuse NO3--N pollution. However, these methods have the potential to cause ‘pollution swapping’: the exchange of one form of pollution as a result of measures implemented to reduce another. Thus the benefits of intercepting NO3--N could be offset by enhanced emissions of the potent greenhouse gases, nitrous oxide (N2O) and methane (CH4), from buffer strips and wetlands. This research aimed to: (1) quantify the direct N2O emissions from an irrigated buffer strip (IBS), using nitrate-rich agricultural drainage water, compared to a non-irrigated control (CP); (2) improve the understanding of N2O production and consumption within soils using controlled soil monolith experiments; (3) assess the effectiveness of a small (60 m2) instream wetland at intercepting and removing diffuse NO3--N pollution, and quantify pollution swapping in the form of CH4 and N2O emissions; (4) assess the production of CH4 and N2O within the sediment, and their emissions as well as inorganic-N concentrations in the overlying water column in response to temperature and turbulence, using intact wetland sediment and membrane inlet mass spectrometry (MIMS). The research focused on mitigating diffuse NO3--N pollution from grazed pasture at a farm in north-east England. Annual N2O-N emissions from the IBS and CP were not statistically different (P > 0.05): 509 and 263 g N2O-N ha-1, respectively, in 2007 and 375 and 500 g N2O-N ha- 1 year-1, respectively, in 2008. Irrigation of the IBS increased spatial variability in flux and generated hotspots of denitrification compared to the CP. However, these changes were short-lived. Direct N2O emission factors (EF1) calculated using the available NO3--loading data (September 2007 - December 2008) for the IBS were lower (c.0.1%) than those calculated for the CP assuming N input from biological N fixation only (<1.9%). Soil monolith experiments under a variety of irrigation and NO3--N loading regimes confirmed low direct and indirect (of dissolved N2O-N in leachate) emissions (<3.1 and <2.3% of applied NO3--N emitted as N2O-N, respectively), similar to the IPCC default emission factors. However, N loss in leachate was high, up to 82% of added NO3--N with concentrations reaching 24 mg NO3--N L-1. Therefore even though no pollution swapping occurred the high leachate losses indicate irrigation of buffer strips are not effective mitigation methods. Monitoring for 2 years of the instream wetland that received median NO3--N concentrations of c. 6 mg N L-1, but up to c. 20 mg N L-1, showed it to be ineffective at intercepting diffuse NO3- pollution: likely a result of the relatively high discharge and short water residence time, as well as the direct input of NO3--N to the wetland from secondary sources: field drains and/or overland flow. The wetland was a net source of NH4+-N in both 2007 and 2008, and a net sink of NO3--N in 2007 only. Annual wetland CH4 and N2O emissions were 713 and 237 mg CH4 m-2 year-1, and 3.5 and 1.9 mg N2O-N m-2 year-1, for 2007 and 2008, respectively and were highly variable between seasons. N pollution swapping was minimal from either direct or indirect emissions, but CH4 emissions were found to be of greater importance at a net cost of ~ £600 ha-1 over the study period (2007 to 2008), compared to N2O emissions (~ £60 ha-1) and low NO3--N interception savings (~ £24 ha-1). Incubation experiments suggest that spatially variable microsites of nitrifying, denitrifying or methanogenic activity and CH4 oxidation occur within the wetland sediment. Therefore off-line, larger wetland systems offer the best prospects of enhanced NO3--N interception and potentially reduced CH4 emissions by maintaining shallow water depths (increased CH4 oxidation) and long residence times (increased opportunity for denitrification), within the wetland or wetland cells.

Seepage from steelmaking coal mine waste rock dumps in the Elk Valley, British Columbia, Canada can contain selenium (Se), cadmium (Cd), and sulfate (SO42-) from the oxidation of sulfide minerals, and nitrate (NO3-) from blasting. The impact of these constituents of interest (CIs) on receiving groundwater systems and the potential for their natural attenuation is investigated. A 10.7 km2 mine-impacted research catchment (West Line Creek) was instrumented with 13 monitoring wells and 8 drivepoint wells to characterize the hydraulics and geochemistry of the aquifer system downgradient of the waste rock dump. These data were augmented with geophysical surveys and by characterizing the lithology, geotechnical properties, and geochemistry of core samples obtained during drilling. Furthermore, the groundwater monitoring program also facilitated the development of a conceptual model of hydrogeology in a small montane valley. An unconfined aquifer at the overburden/fractured bedrock interface, i.e. the basal alluvial aquifer was identified as the primary groundwater conduit for the migration of water and solutes from the waste rock dump toward Line Creek. Vertical and horizontal dispersion of CIs was confirmed with porewater analysis of core samples, with Se concentrations exceeding the BC water quality guideline (2.0 µg/L) in 98% of samples (n = 223). Residence time for groundwater in the overburden aquifers was determined using 3H/3He age dating (n = 3) and estimates of groundwater velocity to be less than three years across the 650 m study site. The chemistry of groundwater was compared with rock drain water samples to evaluate CIs from their source through to identified discharge locations. Linear correlation of CI concentrations with SO42- concentrations in water samples showed that Se and NO3- were conservative solutes, whereas Cd was non-conservative and may be undergoing mineral precipitation or adsorption reactions in the groundwater system. The distribution of CIs in the overburden aquifers was seasonally variable and dilution was determined to be the dominant mechanism controlling the concentrations of conservative CIs (Se, SO42- and NO3-) away from the toe of the waste rock dump and during the spring freshet. The basal alluvial aquifer downgradient of the waste rock dump was estimated to annually discharge 16% of the water and 7% of the SO42- load from the catchment.

<p>A well, situated on Listerlandet in the western part of Blekinge in Sweden, has a very high content of nitrate. Water with a too high content of nitrate is hazardous to human health, in particular to small children. The area surrounding the well is mostly drained agricultural land with some larger farms for chicken and mink. The well takes its water from the bedrock and is deeper than most other wells affected by nitrate. The bedrock in the area is dominated by limestone with a relatively high flow of water.</p><p>This thesis was performed in order to find the source of the nitrate. A groundwater model, simulating the water flow, was created. The model was used to trace the particles flowing to the well in order to find the most likely source. GMS Modflow and Modpath were used to create the model.</p><p>The validation of the model shows that the model is good enough to be used for further investigation of the groundwater in the area.</p><p>The model result indicates that the original source for most of the nitrate is some large mink farms situated on the slope of a hill south of the well. Calculation shows that it takes the water 25 years to flow from the farms to the well. There is also a probable contribution of nitrate from the agriculture in the vicinity of the well. But an extensive drainage system brings most of the water from the cultivated area into the Baltic Sea.</p><p>Conclusions are that a large amount of mink farms placed in a small area contributes to the high content of nitrate in the well. Further examinations are needed to show which measures should be taken in order to diminish the content of nitrate in the well.</p> / <p>En brunn som förser Hörvik med dricksvatten har en hög halt av nitrat. Hörvik ligger på Listerlandet i västra Blekinge. Vatten med för hög nitrathalt är hälsovådligt för människor i allmänhet och spädbarn i synnerhet.</p><p>Området som omger brunnen består till största delen av dränerad jordbruksmark med några större djurgårdar för broiler och mink. Brunnen är bergborrad och går djupare än de flesta andra nitratpåverkade brunnar i Sverige. Berggrunden i området domineras av kalkberg med ett relativt högt vattenflöde.</p><p>Ett projektarbete utfördes för att ta reda på ursprungskällan till nitratet. I arbetet skapades en grundvattenmodell som skulle simulera vattenflödena i området och sedan spåra en partikels väg till brunnen för att ta reda på den mest troliga källan. GMS Modflow och Modpath är de dataverktyg som användes.</p><p>Valideringen av modellen visar att den fungerar tillfredsställande och kan användas för fortsatta undersökningar av grundvattenförhållanden i området.</p><p>Modellresultat tyder på att ursprungskällan för den största delen av nitratet är några stora minkfarmar som ligger på en sluttning upp mot Listers huvud söder om brunnen; dock har det tagit ca 25 år för vattnet att ta sig från ursprungskällan till brunnen. Jordbruket i närheten av brunnen bidrar sannolikt med en del nitrat, men en omfattande dränering leder den större delen av vattnet från jordbruksområdet ut i Östersjön.</p><p>Slutsatsen är att ett stort antal minkfarmar i ett begränsat område är en bidragande orsak till brunnens höga nitrathalt. Vidare undersökningar bör visa vilka åtgärder som behövs för att minska nitrathalten i brunnen.</p>

<p>Nitrogen deposition leads to environmental damage in areas where the nitrogen deposition is high. Southwest Sweden receives an annual nitrogen deposition of up to 20 kg N/ha. Nitrogen that is not assimilated by the vegetation is accumulated in the soil, which may lead to nitrogen saturation and an elevated risk of nitrogen leaching. Nitrogen leaching from forest areas in southern Sweden has proven to be higher than from agricultural areas, which have been thought to be the main contributors to elevated nitrogen levels in rivers and lakes. The amount of nitrogen that leaches depends on the fraction of the total nitrogen in the soil that consists of nitrate, since nitrate is easily transported through the soil. Nitrogen leaching increases after clear-cutting since the uptake by vegetation is greatly reduced.</p><p>In this study the soil chemistry of two clear-cut spruce stands in Halland, in southwest Sweden, has been analyzed. A previous study in these areas has indicated higher nitrate concentrations in the groundwater in one of the areas and thus a greater nitrogen leaching. Nitrogen deposition in the two areas is estimated to be the same and therefore the soil chemistry has been analyzed to evaluate if differences in the soil can have resulted in differences in the nitrate concentration in the groundwater. The hypothesis is that the area with higher nitrate concentrations in the groundwater has properties more favorable for nitrification, which would be especially apparent in a lower carbon to nitrogen ratio. The pH and storage of nitrate, ammonium, total carbon, total nitrogen and exchangeable cations was analyzed in soil samples from both areas. In addition, a study of stand properties and previous use of the areas was made.</p><p>The analyses performed in this study indicate that the soil properties could not explain the differences in nitrate concentration in the groundwater. The differences found between the areas were that the area with lower nitrate concentrations in the groundwater had higher nitrate and ammonium concentrations and higher pH in the soil. The reason for this might be that the soil in this area has larger capacity to bind elements. The fact that the soil samples were sampled during different seasons probably had a major effect on these results. The history and stand properties of the two areas were similar. According to site index one area was more fertile, which benefits nitrification. This fact was not confirmed by the analyses, but it probably caused the nitrification rate to be higher in this area.</p> / <p>Det stora nedfallet av föroreningar i form av kväve i framförallt sydvästra Sverige leder till försurning och övergödning av både skogsmarker och vattendrag. Kvävedepositionen i södra Sverige kan uppgå till 20 kg N/ha och år. Det kväve som inte tas upp av vegetationen ackumuleras i marken som efterhand riskerar att bli kvävemättad vilket ökar risken för kväveutlakning. Kväveutlakningen från svenska skogsmarker har visat sig kunna vara i samma storleksordning som från jordbruksmarker som anses vara en av de största orsakerna till ökande kvävehalter i sjöar och vattendrag. Kväveutlakningens storlek beror till stor del på hur stor del av markens kväveförråd som finns i den oorganiska formen nitrat eftersom den är en lättrörlig jon. Efter skogsavverkning ökar nitratutlakningen betydligt på grund av att det finns väldigt lite vegetation kvar som tar upp kväveföreningarna.</p><p>I den här studien har markkemin i två avverkade granskogsområden i Halland undersökts. Tidigare studier i dessa två områden har visat att halterna av nitrat var högre i grundvattnet i det ena området än i det andra, och således var även nitratutlakningen större i detta område. Eftersom kvävedepositionen anses vara densamma i de två områdena har markemin undersökts för att finna skillnader där som kan förklara de olika nitratnivåerna i grundvattnet. Hypotesen var att det ena området skulle ha mer gynnsamma förhållanden för nitrifikation, framförallt en lägre C/N-kvot. Markens förråd av nitrat- och ammoniumkväve, totalkol, totalkväve, utbytbara katjoner samt pH undersöktes i båda områdena. En studie av områdenas historia gjordes även för att kunna utesluta skillnader där som kunde ge upphov till skillnaden i nitrat i grundvattnet.</p><p>Slutsatsen som kan dras från studien är att de analyserade egenskaperna inte visade på mer gynnsamma förhållanden för nitrifikation i det ena området än i det andra. Ingen skillnad i C/N-kvot uppmättes. Skillnaderna som hittades var att området med lägst halter av nitrat i grundvattnet hade högst halter av oorganiskt kväve i marken och högre pH. Att nitrathalterna var högre i grundvattnet men inte i marken kan ha sin förklaring i att marken i det ena området har större förmåga att binda till sig kväve vilket gör att det inte lika lätt kommer ut i grundvattnet. Antagligen spelade det stor roll för dessa resultat att jordproven tagits vid olika årstider. Undersökningen av tidigare användningsområde i skogarna visade att de hade en tämligen liknade historia. Det ena området har enligt ståndortsindex högre bördighet vilket gynnar nitrifikation. Detta framgick dock inte av analyserna men är antagligen orsaken till de högre nitrathalterna i grundvattnet i detta område.</p>

3 pp. / 1. Drinking Water Wells; 2. Private Water Well Components; 3. Do Deeper Wells Mean Better Water; 4. Maintaining Your Private Well Water System; 5. Private Well Protection; 6. Well Water Testing and Understanding the Results; 7. Obtaining a Water Sample for Bacterial Analysis; 8. Microorganisms in Private Water Wells; 9. Lead in Private Water Wells; 10. Nitrate in Private Water Wells; 11.Arsenic in Private Water Wells; 12. Matching Drinking Water Quality Problems to Treatment Methods; 13. Commonly Available Home Water Treatment Systems; 14. Hard Water: To Soften or Not to Soften; 15. Shock Chlorination of Private Water Wells / This fact sheet is one in a series of fifteen for private water well owners. The one- to four-page fact sheets will be assembled into a two-pocket folder entitled Private Well Owners Guide. The titles will also be a part of the Changing Rural Landscapes project whose goal is to educate exurban, small acreage residents. The authors have made every effort to align the fact sheets with the proposed Arizona Cooperative Extension booklet An Arizona Well Owners Guide to Water Sources, Quality, Testing, Treatment, and Well Maintenance by Artiola and Uhlman. The private well owner project was funded by both the University of Arizonas Water Sustainability Program-Technology and Research Initiative Fund and the USDA-CSREES Region 9 Water Quality Program.

No description available.

<p class=MsoNormal><span style="mso-spacerun: yes">?????????????????? </span>Stable isotopic analysis of nitrate (¹⁵N/¹⁴N and ¹⁸O/¹⁶O) was used to trace nitrate sources and cycling under undisturbed conditions and following harvest at the Turkey Lakes Watershed (TLW), located near Sault Ste. Marie, Ontario, Canada. <span style="mso-spacerun: yes">?? </span> <p class=MsoNormal><span style="mso-spacerun: yes">?????? </span><span style="mso-spacerun: yes">????????????</span>Bulk precipitation collected biweekly at the TLW from 1995 to 2000 had nitrate isotope values that ranged from +42. 4 to +80. 4&permil; for <span style='font-family:Symbol'>d</span>¹⁸O and -6. 3 to +2. 8&permil; for <span style='font-family:Symbol'>d</span>¹⁵N. <span style="mso-spacerun: yes">?? </span>An incubation experiment indicated that the isotopic composition of atmospheric nitrate was not compromised by collection methods whereby unfiltered bulk precipitation samples remain in the collector for up to two weeks. <span style="mso-spacerun: yes">?? </span> <p class=MsoNormal><span style="mso-spacerun: yes">?????????????????? </span>The first direct measurement of the isotopic composition of microbial nitrate produced <i>in situ</i> was obtained by eliminating precipitation inputs to three forest floor lysimeters and subsequently watering the area with a nitrate-free solution. <span style="mso-spacerun: yes">?? </span>Microbial nitrate had <span style='font-family:Symbol'>d</span>¹⁸O values that ranged from +3. 1 to +10. 1&permil; with a mean value of +5. 2&permil;, only slightly higher than values predicted based on the <span style='font-family:Symbol'>d</span>¹⁸O-H₂O of the watering solution used. <span style="mso-spacerun: yes">?? </span><span style='font-family:Symbol'>d</span>¹⁸O values of soil O₂ (+23. 2 to +24. 1&permil;) down to a depth of 55cm were not significantly different from atmospheric O₂ (+23. 5&permil;) and therefore respiratory enrichment of soil O₂ did not affect the <span style='font-family:Symbol'>d</span>¹⁸O values of microbial nitrate produced at the TLW. <span style="mso-spacerun: yes">?? </span> <p class=MsoNormal><span style="mso-spacerun: yes">?????????????????? </span>Nitrate export from two undisturbed first-order stream basins was dominated by microbial nitrate, with the contribution of atmospheric nitrate peaking at about 30% during snowmelt. <span style="mso-spacerun: yes">?? </span>Clear-cutting of catchment 31 in 1997 resulted in elevated nitrate concentrations, reaching levels that exceeded the drinking water limit of 10 mg N/L. <span style="mso-spacerun: yes">?? </span>Isotopic analysis indicated that the source of this nitrate was predominantly chemolithoautotrophic nitrification. <span style="mso-spacerun: yes">?? </span>The <span style='font-family:Symbol'>d</span>¹⁸O values of microbial nitrate in stream 31 progressively increased during the post-harvest period due to an increase in the proportion of nitrification that occurred in the summer months. <span style="mso-spacerun: yes">?? </span>Despite drastic alteration of nitrogen cycling in the catchment by the harvest, <span style='font-family:Symbol'>d</span>¹⁵N-nitrate values in shallow groundwater did not change from the pre-harvest. <span style="mso-spacerun: yes">???? </span>Denitrification and plant uptake of nitrate in a small forested swamp in catchment 31 attenuated 65 to 100% of surface water nitrate inputs following harvest, reducing catchment-scale nitrate export by 35 to 80%.

Cardiovascular disease (CVD) such as hypertension and stroke are serious illnesses that impact on the lives of millions all over the world, with 972 million (26% of the world’s population) suffering from hypertension in year 2000, and an estimated 1.56 billion to be affected by 2025. Hypertension, being one of the most common CVD is associated with the development of stroke, peripheral vascular diseases, myocardial infarction, renal failure as well as cardiac failure. Several studies have shown a seasonal correlation for both the systolic and diastolic blood pressure in mankind. A hypertension trial done by the Medical Research Council in the 1980s showed the average blood pressure being lower in summer than winter, and this difference was more significant in the elderly than the younger population. Other than seasonal variation, blood pressure (including hypertension prevalence) is also noted to correlate with latitude, being higher at places further away from the equator. Other cardiovascular related diseases such as stroke and acute coronary syndrome are also shown occur more frequently in winter. The morbidity and mortality of CVD could be due to various factors including diet, culture, race and social status, but within the United Kingdom, all cause mortality (with cerebral-vascular disease being the major one) correlates with latitude even after accounting for all known risk factors, with CVD risks highest in the north. We propose that this difference in cardiovascular mortality is caused by variations in ultraviolet exposure other than temperature. Known mechanisms of sunlight exposure that affect cardiovascular health include temperature and the ultraviolet B (UVB) mediated photolysis of 7-dehydrocholesterol in the skin to produce 1,25 dihydroxycholecalciferol (Vitamin D). UVB is however a potent skin carcinogen, and calculating risk-benefit ratios for exposure will be important. We believe that independently of vitamin D, nitric oxide plays an important role in blood pressure regulation and cardiovascular health, accounting for seasonal and latitude variation. In 1961, Furchgott demonstrated relaxation of rabbit aorta by irradiating them with ultraviolet light, and in later research he noted this effect is most significant in the ultraviolet A (UVA) spectrum. Recently, Mowbray showed a rich store of various nitro-species within human skin and Oplander showed a reduction of blood pressure in human after giving whole body UVA irradiation. We therefore hypothesize that independently of vitamin D, NO mediates the UVA induced beneficial effects on cardiovascular health. To support our hypothesis, in vivo as well as in vitro studies were conducted. We recruited a total of 63 healthy volunteers and monitored blood pressure, forearm blood flow as well as other cardiovascular parameters before and after UVA irradiation. Blood samples were also taken for the measurement of circulatory nitro-species. We have noted a significant reduction of blood pressure (from 84.5±1.76 to 81.33±1.37 mmHg) and increased forearm blood flow (1.95±0.28 to 2.94±0.47 mL/100mL of tissue/min) after UVA irradiation of human skin; simultaneously, we also noted a rise in circulatory nitrite (0.5±0.04 μM before irradiation to 0.72±0.04 μM) and a drop in circulatory nitrate (11.79±0.64 μM before irradiation and 8.99±0.4 μM). For us to further clarify the role of nitric oxide in different latitude, a monochromator machine that generates specific wavelength of light was been used to irradiate aqueous nitrite solution, and the total amount of nitric oxide release at different latitude was then calculated according to the irradiance of various wavelength across the globe. The results of our studies provide evidence suggesting that nitric oxide release induced by UVA irradiation of the skin can account for the difference in cardiovascular mortality and morbidity by latitude. The current public health advice of avoiding sun exposure to reduce the risk of developing skin cancer may need to be modified.

Nitrite (NO2-) substrate under certain conditions can cause failure of N-removal processes relying on anaerobic ammonium oxidizing (anammox) bacteria. Detoxification of NO2- can potentially be achieved by using exogenous nitrate (NO3-). In this work, continuous experiments in bioreactors with anammox bacteria closely related to “Candidatus Brocadia caroliniensis” were conducted to evaluate the effectiveness of short NO3- additions to reverse NO2- toxicity. The results show that a timely NO3- addition immediately after a NO2- stress event completely reversed the NO2- inhibition. This reversal occurs without NO3- being metabolized as evidence by lack of any 30N2 formation from 15N-NO3-. The maximum recovery rate was observed with 5 mM NO3- added for 3 days; however, slower but significant recovery was also observed with 5 mM NO3- for 1 day or 2 mM NO3- for 3 days. Without NO3- addition, long-term NO2- inhibition of anammox biomass resulted in irreversible damage of the cells. These results suggest that a short duration dose of NO3- to an anammox bioreactor can rapidly restore the activity of NO2--stressed anammox cells. On the basis of the results, a hypothesis about the detoxification mechanism related to narK genes in anammox bacteria is proposed and discussed.

Studies have found that the level of association between an area-level covariate and an outcome can vary depending on the spatial scale (SS) of a particular covariate. However, covariates used in regression models are customarily modeled at the same spatial unit. In this dissertation, we developed four SS model selection algorithms that select the best spatial scale for each area-level covariate. The SS forward stepwise, SS incremental forward stagewise, SS least angle regression (LARS), and SS lasso algorithms allow for the selection of different area-level covariates at different spatial scales, while constraining each covariate to enter at most one spatial scale. We applied our methods to two real applications with area-level covariates available at multiple scales to model variation in the following outcomes: 1) nitrate concentrations in private wells in Iowa and 2) body mass index z-scores of pediatric patients of the Virginia Commonwealth University Medical Center. In both applications, our SS algorithms selected covariates at different spatial scales, producing a better goodness of fit in comparison to traditional models, where all area-level covariates were modeled at the same scale. We evaluated our methods using simulation studies to examine the performance of the SS algorithms and found that the SS algorithms generally outperformed the conventional modeling approaches. These findings underscore the importance of considering spatial scale when performing model selection.