Дисертації з теми "Nitrated case"

Nitrate groundwater pollution in the Osona region is a persistent and widespread problem. Nitrate concentrations are commonly above the drinking water threshold of 50 mg/L in wells and springs. ANOVA and logistic regression analyses showed that nitrate concentration is more dependent on land use than on the geological setting of springs. Nitrate content presented stationary values in most of the springs over time, while discharge and electrical conductivity evolution depends on the geological setting and rainfall events. This is attributed to a homogenization of the subsurface processes that determine nitrate infiltration after decades of intensive fertilization. A multiple linear regression model to assess groundwater vulnerability determined that the factors that significantly influence nitrate pollution are: nitrogen load, aquifer type, presence of well-drained and deep soils, irrigation and occurrence of denitrification processes. Vulnerability maps for unconfined, leaky and confined aquifers were developed and can be used for improving groundwater resources management
La contaminació per nitrats de les aigües subterrànies a Osona és un problema persistent i generalitzat, amb concentracions superiors a 50 mg/L. Les anàlisis ANOVA i regressió logística mostren que la concentració de nitrats és més dependent dels usos del sòl que del context geològic de les fonts. El contingut de nitrats es manté estacionari en la majoria de les fonts al llarg del temps, mentre que l’evolució del cabal i la conductivitat elèctrica depenen del context geològic i la precipitació. Aquesta uniformitat s’atribueix a una homogeneïtzació dels processos que tenen lloc al subsòl i que determinen la infiltració de nitrats. Un model de regressió lineal múltiple per avaluar la vulnerabilitat de les aigües subterrànies ha determinat que els factors que influeixen significativament a la contaminació per nitrats són: la càrrega de nitrogen, el tipus d'aqüífer, la presència de sòls ben drenats i profunds, la irrigació i l’existència de processos de desnitrificació. Els mapes de vulnerabilitat desenvolupats per aqüífers lliures, semi-confinats i confinats són útils per millorar la gestió de les aigües subterrànies

Master of Science
Department of Horticulture, Forestry, and Recreation Resources
Charles J. Barden
Contaminated water poses a major environmental and human health problem, which may be resolved by using the emerging phytoremediation technology. This plant-based cost-effective approach to remediation takes advantage of the ability of plants to concentrate elements and compounds from the environment, to absorb and transpire large amounts of water, and to metabolize various molecules in their tissues. The city of Manhattan’s Biosolids Farm located near Manhattan, Kansas is using the emerging technology of phytoremediation. The Biosolids Farm remediation began in the mid 1990’s; with a large planting of alfalfa with the goal of absorbing excess nitrates from soil and ground water. In 2004, hundreds of trees were planted, to serve as a protective buffer between the biosolids disposal area and the Kansas River. In 2006, a trench study was installed to improve tree establishment on a sandy outwash area close to the Kansas River using Siberian elm seedlings and rooted cottonwood cuttings from Nebraska and true cottonwood seedlings from Missouri. Treatments included trenching, dairy cattle composted manure, and tree shelters. This planting was done to serve as a vegetative barrier and to aid in reducing nitrate movement into the Kansas River. There were interaction between the tree sources and the trenching, compost and shelter treatments. The treatments showed significant interactions with tree sources with the addition of compost and shelters with a p value of 0.0438, and trenching and compost p-value 0.0021. Tree survival was significantly improved with the use of tree shelters.

Ingested nitrate is a precursor of N-nitroso compounds that are carcinogens in animals, with limited evidence in humans. The main objective of this thesis was to evaluate whether the exposure to nitrate through drinking water and diet is associated with carcinogenic effects in humans. This thesis has been conducted in the Centre for Research in Environmental Epidemiology (CREAL) from 2011 to 2015, under the supervision of Cristina M. Villanueva Belmonte PhD. The results of this thesis consists of a compilation of four scientific papers including: a) a descriptive study of nitrate levels in drinking water in Spain (paper I), and b) three large European case-control studies evaluating the risk of prevalent tumors (bladder, breast and colorectal) associated with nitrate exposure through drinking water and diet (papers II, III and IV). This document also includes a general introduction, a description of the methodology, an overall discussion of the results, conclusions and an appendix section.
El nitrato ingerido es un precursor de compuestos N-nitroso, que son carcinógenos en animales, con poca evidencia en humanos. El objetivo principal de esta tesis fue evaluar si la exposición a nitrato a través del agua de consumo y la dieta está asociada a efectos carcinogénicos en humanos. Esta tesis fue llevada a cabo en el Centro de Investigación en Epidemiología Ambiental (CREAL) entre 2011 y 2015, bajo la supervisión de Cristina M. Villanueva Belmonte PhD. La parte principal de esta tesis es una compilación de cuatro artículos científicos, que incluyen: a) un estudio descriptivo de los niveles de nitrato en agua de consumo en España (artículo I) y b) tres estudios caso-control que evaluaron el riesgo de tres tumores prevalentes (vejiga, mama y colorrectal), asociados con la exposición a nitrato a través del agua de consumo y la dieta (artículos II, III and IV). Este documento incluye también una introducción general, una descripción de los métodos, una discusión y conclusiones generales y una sección de anexos.

The tropospheric composition of organohalogens and alkyl nitrates have been investigated from tropical and temperate environments. Ground based measurements and aircraft data are presented from the Oxidant and Particle Photochemical Processes (OP3) project, conducted in Borneo, 2008. Controlled experiments of temperate vegetation were also conducted to assess the emission of methyl halides from crop plants. Methyl halide results from OP3 contradict current assumptions of a strong source from tropical vegetation. High mixing ratios of methyl chloride and chloroform were observed in the boundary layer over oil palm plantations. OP3 aircraft data suggests that the oil palm plantations facilitate the formation of C2 to C4 alkyl nitrates. There was evidence that the southeast coast of Sabah is a source region for the bromocarbons measured. The short lived bromocarbons contribute to a bromine budget of 4- 6 ppt; this corroborates recent modelling estimates of their contribution to the stratospheric burden. In controlled experiments it was confirmed that the gene responsible for the emission of methyl halides is the HOL (HARMLESS TO THE OZONE LAYER) gene. The current WMO estimate for rapeseed contribution to the natural methyl bromide budget was shown to be an overestimate, based on the varieties studied in this thesis. Methyl iodide emissions from rice plants grown in soils were observed to be significantly lower than reported from rice paddies in the literature, suggesting that the growth conditions contribute to the production of methyl iodide.

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.

Orientador: Antonio Celso Novaes de Magalhães
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-07-14T06:11:17Z (GMT). No. of bitstreams: 1 Carelli_MariaLuizaCarvalho_D.pdf: 5522226 bytes, checksum: efa1286b0fd364d39f2226f722cf2a83 (MD5) Previous issue date: 1987
Resumo: A distribuição da atividade da enzima redutase de nitrato ¿in vivo¿, foi estudada em folhas e raízes de plantas jovens de café, cultivadas em areia, em casa de vegetação e irrigadas com solução nutritiva de Hoagland. A otimização da metodologia para a análise da redutase de nitrato ¿in vivo¿ nas raízes mostrou que os valores máximos foram obtidos quando se utilizou como meio de incubação uma solução tampão de fosfato 0,1M , pH 8,0 , em KNO3 50mM. Verificou-se que existe uma relação linear entre a taxa de efluxo dos íons nitrito, resultante da redução de nitrato, e o rempo de ensaio compreendido entre 15 e 45 minutos de reação, que foram então padronizados para a retirada das alíquotas. O borbulhamento contínuo de N2, durante a anáise da redutase de nitrato, aumentou em média 1,3 e 7,5 vezes, respectivamente as atividades enzimáticas das folhas e das raízes, em relação ao controle, sem N2. A atividade da redutase de nitrato, determinada nas raízes mais jovens, foi em média 2,4 vezes maior do que a das secções mais maduras, independente do estádio de desenvolvimento das plantas estudadas. Ao contrário do observado na grande maioria das espécies, a atividade da redutase de nitrato, tanto nas folhas como nas raízes de plantas jovens de café, decresceu durante as horas de luz e aumentou no período escuro. ...Observação: O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital
Abstract: The distribution of the ¿in vivo¿ nitrate reductase activity in leaves and roots of young coffee plants and in leaves of adult plants during the reproductive stage were studied. The young plants were cultivated in sand irrigated with nutrient solution in the greenhouse. The adult plants were cultivated in hydroponics, in ambient conditions. The modified assay of the ¿in vivo¿ root nitrate reductase showed higher values of activity when the tissues were incubated in 0.1 M phosphate buffer, pH 8.0, and 50 mM KNO3, under continuous N2 bubbling, in the dark. With this procedure enzyme activity was 7,5 times higher compared with the control without N2. Young sections reduced nitrate 2.4 times more efficientely than mature sections, independentely of the stage of development of the plant. In young plants, the activity of nitrate reductase in both roots and leaves decreased during the light period and increased in the dark. The observed inhibition of nitrate reduction under illumination apparentely was not due to limitation of photosyntesis and nitrate availability, and suggested that the nitrate reductase reaction would utilize metabolic energy derived from the oxidation of carbohydrate pools. In the dark, nitrate reduction was higher in the roots than in the leaves, the pattern being reversed in the light. ...Note: The complete abstract is available with the full electronic digital thesis or dissertations
Doutorado
Biologia Vegetal
Mestre em Ciências Biológicas

Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, June 1997.
Cataloged from PDF version of thesis. "June 1997." Title as it appears in MIT Commencement Exercises program, June, 1997: Denitrification as a means of addressing vitrate-contaminated groundwater on Cape Cod, MA.
Includes bibliographical references (pages 127-134).
The residents of Cape Cod face a problem of nitrate contamination of their groundwater (their primary source of drinking water) and their coastal and aquatic environments. Groundwater is the only source of drinking water on Cape Cod and the aquifer is defined as a "sole source aquifer" by the Safe Drinking Water Act. While many activities contribute nitrate (NO₃-) contamination to groundwater, nitrate contamination from land application poses the greatest threat on Cape Cod. Only a few small areas on Cape Cod are sewered, and the majority of homes and businesses rely on septic systems. Increased urban development has increased the frequency of installation of septic systems. In many locations, the density of septic systems is greater than the natural ability of the subsurface environment to receive and purify system effluents prior to their movement into groundwater. Many of Cape Cod's environmental resources, including coastal receiving waters, marine embayments threatened with eutrophication, endangered wetlands, and Areas of Critical Environmental Concern (ACECs), are also threatened by nitrate-contaminated groundwater flowing into the coastal waters of Cape Cod, which are extremely sensitive to eutrophication from excess nitrogen loading. In order to address nitrate-contaminated groundwater on Cape Cod, solutions based on biological denitrification should be considered. In this work, these solutions are discussed and explored. First, the major sources of contamination and possible health and environmental effects are discussed. Second, the fate and transport of nitrate in the subsurface environment is analyzed, with a detailed discussion of the factors governing biological denitrification. Third, the current status of groundwater nitrate contamination on Cape Cod is detailed. Fourth, possible options, alternative septic systems and in-situ remedial schemes, which all use biological denitrification as a means of attenuating nitrate in septic system effluent, are presented. Lastly, a proposal for action to deal with nitrate contamination on Cape Cod and suggestions for future study and long-term action for domestic sewage are given, based on my opinion of the scientific and engineering aspects of the circumstances of the contamination.
by Kenneth M. Motolenich-Salas.
M. Eng.

High frequency water quality monitoring presents unique and unlimited opportunities of exploring spatio-temporal variation in water quality. Knowledge gained from analyzing high frequency water quality data can provide more clarity regarding transportation and processing of water constituents over time and space and scale. This study analyzes high frequency discharge, nitrate load and concentration data for three watersheds of different sizes - Cedar River Watershed, North Raccoon and Middle Raccoon. Each of these sites were monitored for 2-3 calendar years. Sudden spikes in discharge, nitrate concentration and load data, also defined as "events" were analyzed in great detail to understand the patterns in event occurrence and event intensity. Smaller watersheds seemed to have sharper and "flashier" events compared to bigger watersheds. Nitrate concentration events were flatter in shape compared to discharge and nitrogen load events. The relationship between nitrogen concentration and discharge was found to be varying over time, unlike the relationship between nitrate load and discharge, which were almost perfectly correlated for most site-year combinations. Based on more than 40,000 simulations, it was determined that high frequency water quality sampling is not only efficient in capturing minute spatio-temporal variations but can also capture nitrate exceedances to a greater degree. High frequency sampling was also associated with higher yield ratio in nitrate load estimates, not only during high flow periods, but also during the non-high-flow period.

Thesis (MScAgric (Soil Science))--University of Stellenbosch, 2009.
ENGLISH ABSTRACT: The sandy soils of the Riverlands Nature Reserve, near Malmesbury, and the neighbouring farm were studied to determine the effects of long term invasion of the legume Acacia saligna on the soil nutrient content of a soil previously vegetated with fynbos. The effect of the removal of this alien legume on general soil properties and groundwater quality were also studied. The changes in nitrates and nitrites (NOX) due to the invasion and removal of the alien legume were investigated in more detail than changes in other soil nutrients. In addition to that emphasis was placed on the effect of vegetation clearing on groundwater quality, specifically relating to potential contamination with nitrates. This study was initiated after Conrad et al., (1999) found increased NOX concentrations in ground water while studying the effects of pig farming on ground water nitrogen (N) near a site cleared of Acacia saligna by Working for Water (WFW). Since many sites are scheduled for removal of this alien vegetation it was deemed necessary to study the effects that clearing alone had on groundwater quality. It was suspected that there would be an increase in soil and groundwater NOX with vegetation removal due to the inputs from the legume alien invader. Soil sampling was done continuously throughout the rainy season of 2007 (From May to December) on three adjacent sites separated by some 50 m of distance, consisting of a natural fynbos site and two Acacia saligna sites. The sites were selected approximately on the same contour line to prevent interaction through lateral water flow. One of the Acacia sites was cleared by the Working for Water programme in the usual manner leaving slash on the ground. Soil samples were collected at regular intervals throughout the season from all three sites (fynbos, Acacia and cleared site) using a Jarrett soil auger. They were airdried (to achieve full oxidation of mineral N) and sieved though a 2mm sieve. Soils were analysed by atomic absorption spectroscopy for basic cations and by ion chromatography for anions, including nitrates and nitrites. Total carbon and nitrogen was determined by combustion, pH (1M KCl and H2O) and EC (1:5 H2O) were also measured. The present study was part of a wider investigation into the quality of groundwater, modelling flow and contaminant transport (Jovanovic et al., 2008). The largest changes in soil properties were observed in the top (0-5 cm) layer. The fynbos site had a lower nutrient status by comparison to the Acacia site and the cleared site. The sum of cations from the soils of the fynbos site at a soil depth of 0-5cm was 100mg/kg and soils from the cleared and Acacia sites were about 190mg/kg. The Acacia site had a higher NOX status and experienced a larger NOX fluctuation during the rainy season than the fynbos site; minimum NOX values were similar (below 10mg/kg) but the Acacia site had a maximum NOX value of near 60mg/kg and the fynbos site just below 30mg/kg. There was little difference in general soil characteristics (exchangeable cations, pH and EC, total soil C and N) during the first season after clearing, between the Acacia and the cleared sites. The effect of soluble nitrogen changes due to alien legume invasion and removal on groundwater quality, relating to NOX, during the first season after clearing, was determined. It was found that the Acacia site had higher NOX concentrations than the fynbos site. At 0-5cm the fynbos site NOX was less than 30mg/kg and the Acacia site was between 30 and 110mg/kg for most of the season, with values lower than 30mg/kg for the last four sampling dates only. N concentrations on the cleared site behaved in a similar manner to the uncleared Acacia site, but generally N values were lower on the cleared site, there were only two sampling dates where the cleared site had higher NOX values than the Acacia site at 0-5cm. The average groundwater N in NOX under the cleared site was 4.34 mg/l, and under the Acacia site 3.78mg/l, these values are both below the level determined for water contamination with nitrates. However, the increase in ground water nitrate levels after A. saligna clearing was significant. It was concluded that there is a change in the nutrient status of soil with Acacia invasion and again with removal. NOX migrates to the groundwater to a larger degree once vegetation has been removed, although during this study the nitrate pollution threshold of 10 mg/l nitrate N was not reached.
AFRIKAANSE OPSOMMING: Die sanderige gronde van die Riverlands Natuur Reservaat, naby Malmesbury, en die aangrensende plaas was bestudeer om die effek van die langtermyn indringing van die peulgewas, Acacia saligna, op die voedingswaarde van ‘n voorheen fynbos begroeide grond, sowel as die effek van die verwydering van die indringer op die algemene samestelling van die grond en grondwater kwaliteit. Oplosbare stikstof veranderings (NOX) wat plaasvind as gevolg van die indringing en verwydering van die indringer peulgewas, was in meer diepte bestudeer as die ander elemente. Klem was ook geplaas op die effek van die verwydering van plantegroei op grondwater kwaliteit, met spesifieke verwysing na potensiële nitraat besoedeling. Die studie was beplan na Conrad et al., (1999) ‘n toename van NOX konsentrasies in grondwater ontdek het, tydens ‘n studie van die effek wat vark boerdery het op grondwater N naby ‘n area waar Acacia Saligna verwyder was deur Working For Water (WFW). As gevolg van die feit dat verskeie areas in die proses is om skoongemaak te word van Acacia Saligna, is dit nodig geag om die effek daarvan of grondwater kwaliteit te ondersoek. Die hipotesis was dat daar ‘n toename in NOX konsentrasies in grond en grondwater sal wees as gevolg van die verwydering van plantegroei. Grond monsters was deurlopend geneem gedurende die reën seisoen van 2007 (Vanaf Mei tot Desember) uit nabygeleë areas wat omtrent 50 meter uitmekaar is. Die volgende tipes grond was verteenwoordig: ‘n Fynbos begroeide grond sowel as ‘n grond begroei met Acacia saligna. Die areas was geselekteer ongeveer op die selfde kontoer lyn om interaksie tussen areas te voorkom as gevolg van laterale water vloei. ’n Gedeelte van die A. saligna area was skoongemaak deur die Working for Water program op die gewone manier deur die afgesnyde plant materiaal op die grond te los. Grond monster was geneem met gereelde intervalle gedurende die seisoen op al drie areas (fynbos, A. saligna, en skoongemaakte area) deur die gebruik van ’n Jarret grondboor. Die monsters was lugdroog gemaak (om volle oksidasie van die mineraal N te verseker) en toe gesif deur ‘n 2mm sif. Die gronde was analiseer deur atoom absorpsie vir basiese katione en deur ioon chromatografie vir anione, insluitende nitriete en nitrate. Totale koolstof en stikstof was bepaal deur verbranding terwyl pH (1M KCl en H2O) en EC (1:5 H2O) ook gemeet was. Hierdie studie was deel van ‘n wyer ondersoek na die kwaliteit van grondwater, vloei modelering en vervoer van kontaminante (Jovanovic et al., 2008). Die grootste veranderinge in die grond eienskappe was in die boonste grondlaag (0-5cm) waargeneem. Die bevinding was dat die fynbos area ‘n laer voedingswaarde het as die area begroei met die indringer sowel as die die skoongemaakte area. Die som van katione onder fynbos grond by ‘n grond diepte van 0-5cm, was 100/mg/kg en die som van katione by die ander twee areas was omtrent 190mg/kg. Die Acacia area het ‘n hoër NOX inhoud en het ‘n groter NOX fluktuasie ervaar gedurende die reën seisoen as die fynbos area. Die minimum NOX waardes was soortgelyk (minder as 10/mg/kg), maar die Acacia area het ‘n maksimum NOX waarde van omtrent 60mg/kg terwyl die fynbos area se maksimum net minder as 30mg/kg gehad het. Daar nie veel verskil tussen die algemene grond eienskappe (uitruilbare katione, pH en EC, totale C en N) van die Acacia en skoongemaakte areas gedurende die eerste seisoen na die indringer verwyder is nie. Die effek van oplosbare stikstof veranderings as gevolg van die peulgewas se indringing en verwydering op grondwater kwaliteit, met verwysing na NOX, gedurende die eerste seisoen na verwydering van die indringer was bepaal. Dit was bevind dat die Acacia area ‘n hoër NOX konsentrasie as die fynbos area het. Op ‘n diepte van 0-5cm was die fynbos NOX laer as 30mg/kg terwyl die Acacia area tussen 30 en 110mg/kg vir die grootste gedeelte van die seisoen was met waardes laer as 30mg/kg vir die laaste vier datums waarop monsters geneem was. Veranderings in N op die skoongemaakte area en die Acacia area was soortgelyk, maar oor die algemeen was N waardes laer op die skoongemaakte area. Daar was slegs op twee datums gevalle gevind waar die skoongemaakte area ‘n hoër NOX inhoud as die Acacia area gehad het by ‘n diepte van 0-5cm. Die gemiddelde N in NOX in die grondwater onder die skoongemaakte area was 4.34mg/l en by die Acacia area was dit 3.78mg/l; hierdie waardes is onder die drempel vir nitraatbesoedeling in grondwater. Die nitraat inhoud van die grondwater het wel beduidend toegeneem as gevolg van verwydering van A. saligna. Die gevolgtrekking was dat daar ‘n verandering plaasvind in die voeding status van grond met Acacia saligna indringing en weer met verwydering. NOX migrasie na die grondwater verhoog met verwydering van plantegroei. In hierdie studie was die nitraat besoedeling drempel van 10mg/l nitraat N nie bereik nie.

In this thesis, the photochemical and photocatalytic degradation of atenolol (ATL) and 2-phenylbenzimidazole-5-sulfonic acid (PBSA) have been investigated in aqueous solutions. Our results show that direct photolysis of ATL is weak and the indirect photolysis, e.g., induced by photosensitizers such as nitrate, may contributed to its major loss process in natural sunlit waters. In the case of PBSA, direct photolysis is found to be important while the indirect photolysis may play a less important role in its elimination in natural surface waters. The photolytic reactions (either direct or indirect) generally obey pseudo-first-order kinetics and can be influence by the solution pH, the co-existence of other water constituents such as dissolved organic matter (DOM) and bicarbonate ion (HCO3-). The photolytic degradation lead to a variety of intermediates and products. However, the reduction in TOC of the photolysis is usually found to be insignificant compared to the disappearance of the mother compound. Nevertheless, the observed decrease in toxicity toward fresh water species D. magna in nitrate-induced photodegradation of ATL implies indirect photolysis of ATL is possibly an important way to reduce the toxicity to ecosystem. It should be noted that direct and indirect photodegradation may process through different pathways and mechanism as observed in the photolysis of PBSA in this work. Photocatalytic oxidation of ATL and PBSA were carried out in illuminated aqueous TiO2 suspensions. Photocatalytic reactions normally follow pseudo-first-order kinetics. The kinetics are strongly affected by the photocatalyst type, the photocatalyst dosage, the solution pH value and the substrate concentration. Hydroxyl radical (HO*) was determined to be the major reactive specie responsible for the remarkable degradation of mother compounds. The degradation efficiency is largely influenced by the water matrices as well as the formation and transformation of intermediates. It should be noted that Degussa P25 showed the highest photocatalytic activity for oxidizing ATL and PBSA compared to pure anatase or rutile catalyst such as Hombikat UV 100, Millennium PC 500 and Aldrich rutile, which is in line with previous reports. The photocatalytic degradation of mother compounds results in the formation of various intermediates (e.g., formic, oxalic, malonic acid) and inorganic ions (e.g., NH4+, NO3-, SO42-). TOC decreases much more slowly as compared to the disappearance of the mother compounds, however, complete mineralization could be obtained with longer irradiation time

>Magister Scientiae - MSc
The water quality in many Cape Town Rivers and streams is a major challenge. Kuils River is subject to multiple land use impacts from upstream to downstream because of rapid urbanization in its catchment area. The main pollution sources are urban and industrial, organic matter from litter under the road-bridge, and golf course. However no systematic efforts have been made to evaluate and improve the health of the river in term of management. To assess impacts on water quality, this study was conducted from 4th September to 27th November 2012 in 5 selected sites in the upper reach of the Kuils river. The main aim was to compare the health of the river in 2012 with that found in 2005 using physical and chemical characteristics and the South Africa Scoring System (SASS). The statistical analysis showed a significant difference between and within sites. The water temperature, pH, dissolved oxygen concentration, total dissolved solids (TDS), and salinity were collected in situ by YSI 30 meter. To evaluate nutrient (nitrate and phosphorus) concentrations water samples were analyzed at UWC laboratory using spectrophotometer. In addition human activities, basic conditions (7.13 to 8.76), high total dissolved solids (416 to to 916.5 mg L¯¹) and salinity (0.31 to 0.71 mg L¯¹) concentrations were influenced by Malmesbury shales. Nitrate (0.1 to 3.1 mg L¯¹) and phosphorus (0.11 to 5.27 mg L¯¹) concentrations and the decrease in dissolved oxygen in November 2012 showed eutrophic conditions of the river. In the tributary site phosphorus (1.32 to 3.62 mg L¯¹) concentrations revealed hypertrophic condition compared to South Africa guideline. Macroinvertebrates sampled showed a total of 28 taxa grouped in 11 orders were sampled. Poor habitat diversity and water quality degradation were principal causes of low species diversity. The South Africa Score System version 5 (SASS5) and Average Score per Taxon (ASPT) indicated that the river is seriously impacted in 2012 compared to 2005 where water quality was in poor condition. The SASS and the ASPT scores were less than 50 and 4.2 at all sampling sites in most part of sampling period.

Chong Lung-wun.
Thesis (M.Sc.)--Chinese University of Hong Kong, 2002.
Includes bibliographical references (leaves 49-58).
Abstracts in English and Chinese.
Acknowledgement --- p.1
Contents --- p.2
Abstract --- p.4
Chapter I. --- Introduction --- p.6
Chapter 1. --- Nitrate therapy for angina patients --- p.7
Chapter 1.1 --- The mode of action of nitrates --- p.8
Chapter 1.2 --- Hypotheses for the nitrate tolerance --- p.9
Chapter 1.2.1 --- The Sulfhydryl depletion hypothesis --- p.9
Chapter 1.2.2 --- Neurohormonal hypothesis --- p.10
Chapter 1.2.3 --- Plasma volumc expansion hypothesis --- p.10
Chapter 1.2.4 --- Free-radical hypothesis --- p.11
Chapter 2. --- Testosterone therapy for angina patients --- p.12
Chapter 3. --- Nitric Oxide and Steroidogenesis --- p.13
Chapter II. --- Materials and Methods --- p.14
Chapter 1. --- Subjects --- p.14
Chapter 2. --- Method for measuring nitrite and nitrate in plasma --- p.16
Chapter 3. --- Method for the determination of total and free testosterone in blood --- p.24
Chapter 3.1 --- Reagent preparation --- p.24
Chapter 3.2 --- Assay procedure for total testosterone --- p.28
Chapter 3.3 --- Assay procedure for free testosterone --- p.29
Chapter 3.4 --- Determination of working antiserum for free testosterone assay --- p.30
Chapter 4. --- Method for the determination of serum Cortisol --- p.31
Chapter III. --- Result --- p.33
Chapter 1. --- Summary of nitric oxide assay performance --- p.33
Chapter 2. --- Summary of total testosterone assay performance --- p.34
Chapter 3. --- Summary of free testosterone assay performance --- p.34
Chapter 4. --- Data analysis --- p.35
Chapter IV. --- Discussion --- p.43
Chapter V. --- Conclusion --- p.47
Chapter VI. --- References --- p.49

Non-point sources of water pollution from agricultural production are a growing problem in British Columbia. In response, the government has adopted the Code of Agricultural Practice for Waste Management. This thesis outlines the environmental impacts of agricultural non-point source pollutants in general, and the difficulties of regulating manure nitrate contamination in particular. This is followed by a brief discussion of the political, social, and economic factors that affect agroenvironmental policy-making. These factors help to set the context for the Code's development. The Code was developed using an industry-government multi- stakeholder negotiation. The goal of the thesis was to describe and evaluate the negotiation process used in the Code's creation, and to evaluate how the process affected the Code's implementation. Qualitative data were gathered through tape-recorded personal interviews with 12 selectively sampled respondents who were involved in the Code's negotiation, and ten selectively sampled respondents who were involved in the Code's .implementation. In addition to the interview transcripts, other sources of data were documents produced during the Code's negotiation, and the proceedings of a non-point source pollution workshop. The major findings were that the Code's negotiation was a productive process (it met eleven of the sixteen criteria for negotiated rulemaking), and i t did increase farmers' awareness of environmental issues. However, it was not sufficient - by itself to motivate farmer compliance. It was concluded that the Code was part of a larger "package" of programs (e.g. cost-sharing programs, Environmental Guidelines booklets, producer conservation groups), that in total are helping to motivate compliance.

Inadequately treated wastewater effluent is harmful to the receiving aquatic environment. Water-borne chemicals and microbial pathogens pose a health risk to anyone living downstream from sewage treatment facilities. This study assessed the effluent from a package plant with a design capacity of 48kℓ/24 hours, servicing 12 household units and a restaurant in Mogale City. Over a 12 month period, fortnightly water samples were collected from ten selected sites including two boreholes, a river and two dams. Standard parameters including physical (pH, EC, temperature, DO and SS), chemical (nutrient concentration) and biological (bacterial counts) were analysed using handheld meters, standard membrane filter techniques and colorimetric methods. One borehole was affected by pathogen and nitrate runoff from an adjacent poultry farm. If regularly monitored, the package plant effectively removed microbes (most samples contained 0 cfu/100mℓ) but above limit COD, ammonia and phosphate was released in the effluent (with maximum values of 322 mg/ℓ, 42.52 mg/ℓ and 7.18 mg/ℓ, respectively). Generally, river and dam water at the site was of good quality.
Environmental Science
M. Sc. (Environmental Science)