This work studied the production of aerosol-phase organic nitrates in both Portland and the Columbia River Gorge (CRG). Ozone and NOx species were investigated for correlation with organic nitrate aerosol, as they function as precursors to the production of organic nitrates. These ambient gas-phase measurements were collected in the same locations as high-volume (Hi-Vol) filters samples, in an urban and rural gorge setting to investigate correlations at the origin of the pollution plume and downwind. A novel Soxhlet extraction method for Hi-Vol filters was developed based on literature and EPA standard methods. Analysis for nitrate production was done by segregating data based on times when the wind blew out of Portland and down the CRG versus times when flow was not westerly. Filters were then compared to ambient gas-phase measurements and derived NO3 radical production rates to look for trends. Wind direction had a strong influence on the concentrations of precursor molecules in the CRG. On days with a westerly wind direction into the gorge, concentrations of the measure aerosol organic nitrates were similar at both sides. This suggests some contribution of a broader regional production of organic nitrates. There was some correlation between the production rate of NO3 radicals and the measured organic nitrate aerosol, suggesting a role for NO3 + VOC production of organic nitrates that later partition to the aerosol phase. This information will better illuminate the fate of nitrogen downwind of pollution sources. The information will also help to create a better understanding of the way topography and meteorological conditions can influence the flow of pollution. Understanding the downwind oxidative chemistry that happens in the CRG would better support both pollution prevention and mitigation efforts.

Thesis (MScAgric (Soil Science))--University of Stellenbosch, 2007. / South Africa is a water scarce country and in certain regions the quantity of surface water is insufficient to provide communities with their domestic water needs. In many arid areas groundwater is often the sole source of water. This total dependence means that groundwater quality is of paramount importance. A high nitrate concentration in groundwater is a common cause of water being declared unfit for use and denitrification has been proposed as a potential remedy. In groundwater of the Marydale district in the Northern Cape Province, nitrate levels are high enough to be of concern for domestic and livestock consumption. A review of the literature indicates that bacterial denitrification of groundwater can be achieved in situ by using a suitable energy substrate. The technology has been tested elsewhere in the world but more certainty is needed on whether it is a feasible option for local groundwater remediation using local, cost-effective energy substrates and exploiting bacterial populations present naturally in the regolith. The objective of this study was to perform denitrification experiments by laboratory incubation using soil and groundwater samples collected in Marydale in order to determine; 1) The effectiveness of different carbon sources; 2) The effect of using soil sampled at different depths; 3) The effect of C:N ratio of the carbon substrate; and 4) The quality of resultant water. Various experiments were set up using 10 g soil and 40 mL groundwater with different concentrations of carbon sources (sawdust, glucose, maize meal and methanol). All experiments were done under a nitrogen atmosphere to exclude oxygen and temperature was kept constant at 23 °C. Indicator parameters were selected based on literature review, and major cations and anions and some metals were analysed for initially and at selected times during each experiment to evaluate whether major ion chemistry was changing over time. Parameters analysed in supernatant solutions after varying periods of time to indicate progress of denitrification and reduction included nitrate, nitrite, sulfate, alkalinity, chloride, acetate, basic cations, ammonium, pH, electrical conductivity, dissolved organic carbon, heteThe Marydale groundwater in some boreholes is of predominantly NaCl type and the nitrate concentration of 19-32 mg/L as N exceeds ideal limits for drinking water of 6mg/L as N . Two soil materials were sampled at different depths from a red sand overlying calcrete (Plooysburg form, Family Py1000). The incubation experiments showed denitrification was complete within a period of between 1 and 6 weeks depending on the carbon substrate and C:N used. Higher rates of nitrate removal were achieved where greater C:N was used. Readily degradable carbon substrates e.g. glucose showed rapid denitrification, while sawdust, a slowly degradable substrate, effected slower denitrification, hence it was concluded that intermediately degradable carbon substrates e.g. wheat straw may prove more suitable. Use of shallower soil material containing initially higher nitrate levels resulted in better denitrification rates, however, both soil materials effected denitrification.. Heterotrophic plate counts increased with time, this presence and growth of heterotrophic bacteria confirmed that conditions were optimum for growth and denitrification and that inoculation with bacteria is not a requirement for in situ denitrification. Dissolved organic carbon (DOC) concentration could be directly correlated to the initial input of carbon substrate as soil and groundwater lacked organic material. Results showed that reaction products such as acetate and nitrite, and basic cation concentrations were elevated in the supernatant solution in preliminary experiments. This was interpreted to be attributed to incomplete oxidation of organic material and excess soluble and available carbon for reaction. Cation concentrations were interpreted to have resulted from a decrease in pH brought on by organic acids produced during denitrification. The method used showed specificity, as the only parameters affected by the denitrification experiment were DOC, alkalinity, nitrite, nitrate, and the heterotrophic plate count. The DOC and HPC did not comply with acceptable levels for drinking water. Removal of HPC by boiling or chlorinating is required to ensure that the resultant water composition is of potable quality. For further research with slowly degradable carbon sources it is recommended that a C:N ratio of more than 12 should be employed, and monitoring should focus on soluble carbon nitrate, nitrite, and heterotrophic plate count. The study confirmed that denitrification of this groundwater with a range of carbon sources is possible within a short period of anaerobic contact with local soil material. With sufficient knowledge of the characteristics of the soil and groundwater in the area, establishment of a working in situ denitrification plant is probably feasible.

Graduation date: 1995

The aim of process industries is to produce products and intermediates from raw materials and other intermediates. Inevitably, there are waste products to be disposed of and if these are of no use, they must be returned to the air, water or land environments. Such returns should be carried out in such a way as to minimise any adverse effects on the environment, otherwise the waste is bound to cause pollution to the environIDent. Wastewater is one such product that has to be returned to the environment. A weakness in the current practice of wastewater treatment is that the potential toxicity of the effluent is only addressed through the prevention of specific types of waste being discharged to the sewer. The discharge of effluents containing toxic or inhibitory substances is currently not directly addressed or controlled by many industries and local authorities. While cost recovery is important, due consideration must be given to the possible effect on the receiving environment. The magnitude of the problem of toxic components in the inflow to wastewater treatment plants in South Africa is largely unknown. However, it is thought by some treatment authorities to be relatively serious. In addition, there has been no attempt to quantify the effect of individual toxicants on the performance of the treatment processes and thus put a monetary value to individual discharges. Nitrification is one of the important biological processes that takes place in wastewater treatment plants, which may be affected by toxicants from wastewater. The toxicants may inhibit the nitrification process and create problems in the treatment plant. The aim of this study was to determine if the Amanzimtoti Wastewater Treatment Plant is experiencing inhibition of nitrification, and if so, determine whether large industries discharging into the plant contribute to this problem. The study site used in this research was the Amanzimtoti Wastewater Treatment Plant, located at Isipingo, in Durban, together with some selected industries that discharge their effluents into this treatment plant. In this study, the Amanzimtoti Wastewater Treatment Plant together with lO industries that discharge effluent into it, were surveyed for inhibition of nitrification. A screening method for estimation of inhibition of nitrification at municipal wastewater treatment plants described by Jonsson (2001) was used in the investigations. This involved testing inhibition of nitrification at various dilutions of wastewater effluent from 20% to 80% dilution. An investigation was conducted of inhibitory substances within influent wastewaters to the Amanzimtoti Wastewater Treatment Plant, and inhibitory substances were detected in all four sampling weeks. The level of inhibition was in general up to 29%, with the greatest inhibition being observed at 20% and the least at 80% dilution. In order to investigate the source of inhibition, inhibition of nitrification was measured in the sewage influent during times when industries are open and when they are closed. Inhibition was significantly lower during December when industries close, supporting the hypothesis that industrial effluent contributes to inhibition of nitrification. Comparison of wastewater from different industries showed that of 10 surveyed industries, 9 generated wastewaters that were found to be inhibitory, with Industry D showing the highest inhibition of approximately 30% over the 4 dilutions. The least inhibitory effluent was from Industry C with an average of 10%. Industry A was found to stimulate nitrification. There was no correlation found between the daily volume contribution of the industries to the treatment plant, and the inhibition of nitrification. There was also no correlation found between the inhibition of nitrification and the chemical oxygen demand and settleable solids concentration of wastewater from each of the industries.. At 80% dilution, the nitrification inhibition results obtained for all nine industries were similar and it was difficult to distinguish between them, whereas at 20% dilution, the differences among the industrial effluents on nitrification could be clearly evaluated. Industries B, D, E, G and J were found to have higher inhibition than the other four surveyed industries. Results obtained at the 20% dilution could therefore be used as a decision making tool by wastewater pollution officers to identify industries requiring close monitoring. From the study, it was clear that the inhibition of nitrification that resulted from mixtures of industrial wastewaters cannot be readily predicted from nitrification inhibition by the individual wastewaters. New compounds may be formed during mixing in the sewer network that are more or less inhibitory than if the wastewaters are not mixed. / Thesis (M.Sc.)-University of KwaZulu-Natal, Durban, 2005.

Nitrate concentration in excess of national drinking-water standards (10 mg/l) are present in the shallow alluvial aquifer and Saddle Mountains Basalt (SMB) aquifer in the Lower Umatilla Basin, Oregon. To determine sources responsible for elevated nitrate concentrations in the SMB aquifer mass-balance and reaction-path models (NETPATH and PHREEQE) were used to understand observed geochemical trends. Nitrate-nitrogen isotopes were used to distinguish potential nitrate sources in the shallow alluvial aquifer. NETPATH-validated simple water/rock reactions in the SMB aquifers in Irrigon (dissolving glass, precipitating smectite, dissolving or precipitating calcite, and cation exchange) using constituents (calcium, magnesium, sodium and carbon). Diversity of composition for the shallow alluvial water and limited number of wells available made obtaining a mass balanced solution for the SMB aquifer near Boardman impossible. Irrigon basalt groundwaters were consistent with the PHREEQE models prediction of natural hydrochemical trends, where Boardman basalt groundwaters plotted consistently with impacted alluvial groundwater. Nitrogen-isotopic values of nitrate (o 15NNo3) were measured in the shallow alluvial groundwater from 17 wells in 4 land-use settings, 3 lysimeter samples and 1 surface water effluent sample. The landuse setting and corresponding average ranges for nitrate concentrations (as N) and 015NNo3 values for wells near: commercial fertilizer-irrigated fields range from 25-87 mg/l, +3.5 to +4.6 per mil; explosive washout lagoons ranged from 10-18 mg/l, +4.6 to +4.9 per mil; potato waste water application ranged from 6.4-17.8 mg/l, +4.4 to +35 per mil; past confined animal feeding operations (CAFO) ranged from 16-56 mg/l, +4.9 to 10.4 per mil; lysimeters 5.4-39.9 mg/l, +9.1 to +21.9 per mil; surface water effluent ranged from 60-61 mg/l, +3.5 to 6.5 per mil; and varying landuse ranged from 9.3-19.5 mg/l, +2.7 to +7.1 per mil. Commercial fertilizer 0 15NNo3 signatures are consistent for this source. Explosive 015NNa3 values are consistent with an atmospheric signature. CAFO o15NNo3 signatures probably result from mixing between currently applied commercial fertilizer and past CAFO's. High 015NNo3 Signatures (+22 to +35 per mil) imply denitrification. Potato waste water and varying land-use 015NNo3 signatures indicate probable mixing of nitratenitrogen sources in the groundwater.

The feedbacks between hydrology and biogeochemical cycling of nitrogen (N) are of critical importance to global bioavailable N budgets. Human activities are dramatically increasing the amount of bioavailable N in the biosphere, which is causing increasingly frequent and severe impacts on ecosystems and human welfare. Streams are important features in the landscape for N cycling, because they integrate many sources of terrestrially derived N and control export to downgradient systems via internal source and sink processes. N transformations in stream ecosystems are typically very complex due to spatiotemporal variability in the factors controlling N biogeochemistry. Thus, it is difficult to predict if a particular stream system will function as a net source or sink of bioavailable N. A key location for N transformations in stream ecosystems is the hyporheic zone, where stream and ground waters mix. The hyporheic zone can be a source of bioavailable N via nitrification or a sink via denitrification. These N transformations are regulated by the physical and biogeochemical conditions of hyporheic zones. Natural heterogeneity in streams leads to unique combinations of both the physical and biogeochemical conditions which in turn result in unique N source and sink conditions. This dissertation investigates the relationships between physical and biogeochemical controls and the resulting fate of bioavailable N in hyporheic zones. The key physical factor investigated is the supply rate of solutes which is a function of transport processes - advection and dispersion, and transport conditions - hydraulic conductivity and flowpath length. Different physical conditions result in different characteristic residence times of water and solutes in hyporheic zones. The key biogeochemical factors investigated are the dynamics of oxygen (O₂), labile dissolved organic carbon (DOC), and inorganic bioavailable N (NH₄⁺ and NO₃⁻). This dissertation uses ¹⁵N isotope experiments, numerical modeling of coupled transport of the bioavailable N species, O₂ and DOC, and a suite of geophysical measurements to identify the key linkages between hydrological and biogeochemical controls on N transformations in hyporheic zones. Specifically, it was determined that the conditions governing the fate of hyporheic N are both the physical transport and reaction kinetics – the residence time of water and the O2 uptake rate. An important scaling relationship is developed by relating the characteristic timescales of residence time and O₂ uptake. The resulting dimensionless relationship, the Damköhler number for O₂, is useful for scaling different streams hyporheic zones and their role on stream N source – sink dynamics. More generally, these investigations demonstrate that careful consideration and quantification of hydrological processes can greatly inform the investigation of aquatic biogeochemical dynamics and lead to the development of process-based knowledge. In turn, this process-based knowledge will facilitate more robust approaches to quantifying and predicting biogeochemical cycles and budgets. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from Sept. 21, 2011 - March 21, 2012

Soils of 49 agricultural and 2 "native condition" sites in the Lower Umatilla Basin, Oregon were sampled for nitrate-nitrogen, ammonium-nitrogen, chloride, and pH beginning in Fall of 1992. Several sites were sampled in Spring and Fall 1993 in order to indicate movement or loss of residual soil nitrogen over time. This study was prompted by current concern over contamination of public drinking water supplies by nitrate and the designation of over 550 square miles of this region as a Ground Water Management Area. This study sought to identify links between agricultural management practices-primarily irrigation, fertilization, and crop rotation systems, and deep soil nitrate levels. Soil profiles were divided into 3 "management zones:" 0-3', 3-6', and beyond 6' in depth. These depths represent average rooting depths for the major agricultural crops of the study area. In general, the effective rooting depth of most area-crops does not extend beyond 6', therefore, it was determined that residual soil-nitrate found at this depth or beyond may be a potential source of ground water contamination if not managed correctly. Results of the study indicate that proper management of irrigation, fertilization, and cropping rotation can significantly reduce the potential for contaminating ground water. Deep soil nitrate levels under most agricultural fields were consistent with the concept that some loss of nitrate below the root zone is inevitable, however, this condition can be minimized through intensive crop management. This study concludes that responsible management of agriculture can minimize impacts on ground water, while providing quality food and fiber products to an ever-growing population. In addition, more research is needed in the area of crop physiology and response to intensively managed systems. Such research may provide insight into more efficient methods of crop production and environmental protection. / Graduation date: 1995

Rain gardens are low impact developments designed to mitigate a suite of issues associated with urban stormwater runoff. The site for this study was a Denton City rain garden at the Denton Waste Water Treatment Plant. Nitrogen and phosphorus removal was examined in light of two overflow events comprised of partially treated wastewater from an upslope anaerobic digester pond. Nitrate removal efficiency was examined across differing dry spell intervals of 5, 8, and 12 d, displaying a moderate negative correlation (r2 = 0.59). Continued phosphorus removal capacity was assessed, showing phosphorus removal in cases where P was in excess of 0.8 mg/L, reflecting an equilibrium phosphorus concentration. A high expanded shale component in the soil media (25%) was likely a factor in the continued removal of phosphorus. Overall the rain garden proved to be a large source of nitrate (+425%) and total nitrogen (+61%) by mass. The study showed that while the rain garden intercepted a large volume of partially treated wastewater during the overflow events, preventing it from reaching a nearby creek, the mitigation of an acute event has extended to a chronic one as nitrogen is gradually processed and flushed from the system as nitrate.

This study utilized GIS and statistical methods to map the spatial variability of nitrate and related groundwater constituents in 30 counties above the Seymour Aquifer, analyze temporal patterns of nitrate pollution, identify probable sources of pollution, and recommend water development strategies to minimize exposure to nitrate and reduce future aquifer contamination. Nitrate concentrations in excess of 44 mg/L (US EPA limit) were commonly observed in the Seymour Aquifer region, especially in the central agricultural belt. Data indicated that this is an ongoing problem in the Seymour Aquifer and that agricultural activity and rural septic systems are the likely sources of the nitrate. Inconclusive results emphasized the need for a more comprehensive spatial and temporal water quality monitoring.

Excessive nitrates in drinking water pose a human health threat, especially to infants. Methemoglobinemia, or blue-baby syndrome, is a potentially fatal condition that inhibits the ability of red blood cells to bind and transport oxygen. Nitrates/nitrites have also been linked to such conditions as cancer, birth defects, and behavioral and developmental abnormalities. Nitrates are frequently found in wells in rural farming areas because synthetic fertilizers (containing nitrates) leach from the soil into the groundwater. The Lower Umatilla Basin (LUB) in Morrow and Umatilla counties of Oregon represents an intensively farmed and irrigated area in which relatively high amounts of nitrates are present in the groundwater and domestic well water. This study investigated population demographics for the rural Lower Umatilla Basin, comparing these data to identified well-water nitrate levels for the purpose of estimating nitrate exposures and potential risk of adverse health effects in the survey area. Results of the investigation revealed that 25 percent of the domestic-use wells in the survey area had nitrate levels that were in excess of the 10 ppm nN MCL for drinking water, as established by the U.S. Environmental Protection Agency. From access to these wells, 23 percent of the surveyed population was exposed to nitrate concentrations in excess of the MCL standard. However, resident infants were neither exposed to well-water nitrates in excess of the standard, nor were they exposed to illness that could have increased the risk of methemoglobinemia. The LUB survey population was generally older than the populations from cities in the LUB or the combined populations of rural areas of Morrow and Umatilla counties. The population included few women of childbearing age, and it was not subject to an appreciable increase in the proportion of younger to older families. These factors reduced the likelihood of a significant increase in the infant population, which also minimized the risk of methemoglobinemia to this population. Even though the risk of methemoglobinemia to infants was low in the LUB area, it is recommended that exposures to well-water nitrates be prevented, if possible even for adults, to reduce the potential for chronic, adverse health effects from excess nitrate ingestion. Continued monitoring of private wells by state agencies is recommended, with attention directed at domesticuse wells with nitrate levels in excess of 10 ppm nN. This information should be shared with local health departments for follow-up, investigation, and educational efforts as needed. Future studies by the Oregon DEQ, or other agencies which seek to document the sources of well-water nitrate contamination in the LUB, should include an investigation of the influence of local sources of nitrate contamination. / Graduation date: 1993