A estrutura das comunidades de arquéias e bactérias amônio oxidantes (AOA e AOB, respectivamente) e de bactéria fixadoras de nitrogênio de vida livre (BFNVL) foi avaliada em amostras de solo coletadas em três áreas de Mata Atlântica do Estado de São Paulo (Santa Virgínia, Picinguaba e Restinga) por meio de metodologias independentes de cultivo. Após a extração do DNA do solo, o perfil das comunidades de AOA, AOB e BFNVL foi acessado por PCR-DGGE e seus respectivos genes, amoA, 16S DNAr e nifH, quantificados por meio de qPCR. Além disso, foi realizado o pirosequenciamento do gene 16S DNAr da região V3 em arquéias e da região V4 de bactérias. Os dados foram submetidos às análises de redundância (RDA) e similaridade (ANOSIM) e ao teste de Mantel. Foram observadas diferenças significativas na estrutura das comunidades de AOA, AOB e BFNVL, sugerindo que a cobertura vegetal, assim como os atributos físico-químicos do solo, influencia a atividade destes micro-organismos nas três áreas. Santa Virgínia e Picinguaba apresentaram maior abundância de AOA e AOB, sendo AOA proporcionalmente mais abundante do que AOB em todas as áreas. Já as comunidades de BFNVL foram mais abundantes em Santa Virgínia e Restinga. A diversidade das comunidades de Crenarchaeota foi similar entre as áreas, porém, Picinguaba revelou maior diversidade de unidades taxonômicas operacionais (UTOs). Este trabalho possibilitou uma primeira exploração da diversidade e abundância das comunidades de AOA, AOB e BFNVL nos solos de Mata Atlântica do Estado de São Paulo, sendo que as informações obtidas poderão auxiliar futuros estudos sobre o entendimento do papel destas comunidades no ciclo global do nitrogênio na Terra. / The community structure of ammonia-oxidizing archaea and bacteria (AOA and AOB, respectively) and free-living nitrogen-fixing bacteria was evaluated in soil samples collected in three areas of Atlantic forest of São Paulo (Santa Virgínia, Picinguaba and Restinga) using culture-independent molecular techniques. After DNA extraction from the soil samples, AOA, AOB and BFNVL profiles were accessed by PCR-DGGE, and their respective genes (amoA, nifH and 16S rDNA) were quantified by qPCR. In addition, it was performed the pyrosequencing of the 16S rDNA variable V3 and V4 regions of archaea and bacteria, respectively. The data were subjected to redundancy analysis (RDA); analysis of similarity (ANOSIM); and the Mantel test. There were significant differences in the AOA, AOB and BFNVL community structure, suggesting that the vegetation cover and the physical and chemical attributes of soil influences the activity of these micro-organisms from the three areas. AOA and AOB were more abundant in Santa Virginia and Picinguaba, and AOA was more abundant than AOB in all areas. On the other hand, BFNVL communities were more abundant in Santa Virginia and Restinga. The diversity of Crenarchaeota communities was similar among the three areas, however, Picinguaba revealed greater diversity of operational taxonomic units (OTUs). This study allowed the first evaluation of the diversity and abundance of AOA, AOB and free-living nitrogen-fixing bacteria communities in the soils of the Atlantic Forest of the São Paulo State, Brazil. The information obtained here will support future studies focused on the role of these communities in the global nitrogen cycle on Earth.

No description available.

Communicating science in three-dimensional (3D) multimedia is an immersive and interactive way to explore scientific processes (Signals and Communication Technology, 2019). Geovisualization is an emerging 3D multimedia method for visual analysis, synthesis, and presentation of geospatial, geologic, and geophysical data (MacEachren & Kraak, 2001). There is an identified need to develop scientific communication tools to further understand boreal peatland evolution, hydrogeology, ecology, and geochemistry (Bubier et al., 2003) since the International Union of Conservation of Nature asserts that peatlands are among the most valuable ecosystems on Earth, critical for preserving global biodiversity, providing drinking water, minimising flood risk, preventing wildfire, and mitigating climate change (Hama et al., 2000). The intention of this thesis is to communicate a novel approach to geovisualize boreal peatland architecture using Light Detection and Ranging (LiDAR) and Ground Penetrating Radar (GPR). GPR and LiDAR have been used to create 3D subsurface geovisualizations for archaeology (Kenady et al., 2018; Schultz & Martin, 2011) and resource geology (Corradini et al., 2020; Koyan & Tronicke, 2020) although application to peatland hydrogeology is uncommon. Point-source hydrogeological and geochemical data were integrated with 3D geological models to estimate carbon and nitrogen storage in an archetypal boreal peatland near Mariana Lakes, Alberta. Peatland geometry resembled a shallow lake basin with depths greatest in fens (>10 m) and thinnest in bogs (<2 m). Hydraulic conductivity was only a few meters per year and vertical groundwater movement was limited. Sequestered carbon and nutrients increased with depth. The average concentration of dissolved ammonium was 3 grams per cubic metre of peat (g/m3), 5g/m3of Total Kjeldahl Nitrogen, 60g/m3 of dissolved organic carbon and 200g/m3 of dissolved inorganic carbon. Tritium detection from atmospheric atomic weapons radionuclide fallout revealed that in deeper anaerobic peat (catotelm), tritium was absent, signifying groundwater was older than 50 years and not mixed with meteoric waters. Fen catotelm channels are likely acting as gravity-driven hydraulic traps (Tóth, 1999). / Graduate

Maize is the dominant crop in northwestern Germany and is mostly cultivated on sandy soils. Additionally, due to intensive livestock husbandry and biogas production, large amounts of liquid manures are produced. The current farm practice leads to high N and P surpluses at field level accompanied by environmental pollution, like nitrate leaching, eutrophication of non-agricultural ecosystems, and N2O emissions. The accruing liquid manures are often used for maize fertilization. Thereby, slurries are mainly broadcast applied using trailing hose applicators followed by incorporation into the topsoil. In addition, a mineral N P starter fertilizer (MSF) is band-applied below the seed-corn at planting to overcome the limited nutrient availability during the early growth stages. Using a slurry injection technique below the maize row before planting might serve a substitute for MSF. Addition of a nitrification inhibitor (NI) into the slurry before injection seems to be an option to further decrease N losses. The objectives of this thesis were to compare the current and novel fertilizing strategies with a special focus on soil mineral nitrogen (SMN) dynamics and plant P, zinc (Zn) and manganese (Mn) status. For both issues the effect of adding a NI into the slurry was investigated. To characterize the SMN dynamics after slurry injection an appropriate soil sampling strategy had to be developed. Therefore, three consecutive field trials were conducted. The first testing of the new soil sampling approach was implemented in an existing experiment where the slurry was injected at a depth of 12 cm (upper rim) below the soil surface. The soil profile (75 cm wide) centered below the maize row was sampled using a grid-like approach to a depth of 90 cm. Around the injection zone, soil monoliths (SM) were sampled using a purpose-built soil shovel. Below the SMs and in the interrow space (15 and 30 cm distance to the row) a standardized auger procedure was used. The second experiment aimed to improve the sampling strategy with focus on sample homogenization quality and necessary sample sizes per pooled sample. In the third experiment this improved sampling strategy was validated. Results from the first testing of the sampling procedure showed that the strategy is suitable, although some problems occurred. Especially the high spread in values among the replications caused high coefficients of variation (CV; mostly 40 – 60%). The improvement trial revealed that for the SM, which contains the slurry band, an intensive homogenization is required. In addition, suitable sample sizes (twelve auger samples and six soil monolith samples per pooled sample) have to be collected to obtain reliable SMN values. Following this enhanced sampling strategy in the final validation trial, the spread in values was considerably reduced and resulted in CV values of mostly < 20%. The method can be adapted to other fertilizer placement strategies and further row crops. To compare both fertilizing strategies with respect to the spatial and temporal SMN dynamics as well as to the plant nutrient status two field trials were conducted using pig slurry on sandy soils in 2014 and 2015. Four treatments were tested: unfertilized control, broadcast application + MSF, injection, and injection + NI. Soil samples were taken using the new sampling strategy at several dates during the growing season. Plant samples were simultaneously collected to evaluate the plant P, Zn, and Mn status at different growth stages. In 2014, all fertilized N was displaced from the top soil layer of the broadcast treatment until the 6-leaf stage due to heavy rainfall, while N displacement was significantly smaller after slurry injection. The lateral movement of injected slurry N was negligible. In 2015, almost no displacement of fertilized N out of the top soil layer occurred independently of treatments, due to distinctly lower rainfall. The release of slurry N was delayed following broadcast application and large SMN concentrations were detected in the injection zones until the 10-leaf stage. The addition of a NI resulted in significantly increased NH4-N shares in the injection zone throughout the early growth stages (+ 46% in 2014 and + 12% in 2015 at 6-leaf stage). Thus, in 2014 SMN displacement was delayed, and in 2015 increased SMN concentrations were found around the slurry band, most probably due to lower N losses via denitrification. Furthermore, NI addition significantly increased the nutrient uptake by maize during early growth in both years. With P deficiency due to cold weather conditions in 2015, broadcast application showed higher P uptake until the 6-leaf stage (36 – 58%), while it was lower at the 8- (32%) and 10- (19%) leaf stages compared to slurry injection (+ NI). Zn availability was enhanced during early growth after slurry injection (+ NI) and Zn as well as Mn uptake were higher at harvest. Furthermore, dry matter yields were higher (2014) or equal (2015) compared to broadcast application. The P balances were decreased by 10 – 14 kg P ha-1, while Zn and Mn balances were excessive independent of treatments. The field trials showed that after slurry injection, especially when combined with a NI, the applied nitrogen is located in a soil zone with better spatial availability for plant roots compared to broadcast application. Furthermore, the MSF can be substituted without affecting early growth of maize. In conclusion, slurry injection leads to equal (or even higher) yields and enables farmers in northwestern Germany to reduce the P and N surpluses. This would support several goals concerning sustainable land use: Lower pollution of ground and surface waters, reduced emission of NH3, more efficient use of the limited rock P reserves, and less need of transporting organic manures out of regions with intensive animal husbandry and/or biogas production. However, slurry injection enhances the risk of N2O emissions, which contributes to climate change. Thus, for a final evaluation of the environmental impact a life cycle assessment would be worthwhile.

Soil aquifer treatment was simulated in 1 m laboratory soil columns containing silica sand under saturated and unsaturated soil conditions to examine the effect of travel length through the unsaturated zone on the removal of wastewater organic matter, the effect of soil type on dissolved organic carbon removal and also the type of microorganisms involved in the removal process. Dissolved organic carbon removal and nitrification did enhance when the wastewater travelled a longer length through the unsaturated zone. A similar consortium of microorganisms was found to exist in both saturated and unsaturated columns. Microbial concentrations however were lowest in the soil column containing silt and clay in addition to silica sand. The presence of silt and clay was detrimental to DOC removal efficiency under saturated soil conditions due to their negative effect on the hydraulic performance of the soil column and microbial growth.

No description available.

[ES] Los procesos convencionales de depuración del agua residual presentan un elevado consumo energético y no permiten la recuperación de los recursos presentes en el agua. En la transformación de las Estaciones Depuradoras de Agua Residual (EDAR) en estaciones de recuperación de recursos, los procesos de redirección de carbono, como la ultrafiltración del agua residual (UF), juegan un papel crucial. Esta tecnología envía toda la materia orgánica suspendida y parte de la soluble a la digestión anaerobia. Tras la filtración, la línea principal de aguas presenta una composición diferente a la tradicional, principalmente una baja ratio de materia orgánica por unidad de nitrógeno (DQO/N) ausencia de sólidos suspendidos. Esta tesis doctoral tiene como objetivo estudiar experimentalmente, y con modelos matemáticos, diferentes alternativas de tratamiento del permeado de una planta piloto de UF de agua residual urbana real para lograr un efluente que cumpla con los requisitos de vertido. Los esquemas propuestos permiten aprovechar las infraestructuras existentes de las EDARs. La tesis está estructurada en cuatro bloques: 1- Estudio proceso convencional de nitrificación-desnitrificación (ND). Los resultados indican que el proceso de filtración retiene una elevada concentración de materia orgánica y reduce la ratio DQO/N por debajo de las condiciones estequiométricas necesarias, provocando que no todo el nitrógeno pueda ser eliminado mediante ND. Para poder mantener este tratamiento se necesitaría baipasear una parte del agua de entrada al proceso de filtración, para ajustar la ratio DQO/N al valor necesario, o aplicar esta alternativa en aquellos influentes con una alta concentración de materia orgánica soluble, ya que una parte de esta fracción no será retenida. 2- Evaluación del proceso de nitrificación parcial (NP) seguido del proceso Anammox. Ambas etapas biológicas no requieren de materia orgánica para la eliminación del nitrógeno y su consumo energético es menor, al reducir las necesidades de aireación. Experimentalmente se estudió el proceso de NP en la línea principal de aguas. Regulando la duración de la fase aerobia mediante un controlador basado en el pH y el oxígeno, mantenido una concentración de oxígeno de 0.5 mg O2/L y tiempos de retención celular de 3 a 10 días, se consiguió acumular N-NO2 en el reactor. El modelo matemático confirmó la importancia de estos parámetros de operación. 3- Concentración del nitrógeno mediante columnas de intercambio catiónico (IC) y recuperación en contactores de membranas (HFMC). Inicialmente se seleccionó el material adsorbente a partir de los resultados de los ensayos de cinéticas de adsorción. La zeolita natural, el material escogido, se caracterizó y se analizó la influencia de los interferentes mediante las isotermas de adsorción. También se analizó qué regenerante ofrecía mejores resultados. Por último, se realizaron varios ensayos en columnas de adsorción para estudiar la influencia del caudal de trabajo y la concentración de amonio en el afluente sobre la capacidad de adsorción de amonio y el volumen de permeado tratado antes de alcanzar el punto de ruptura. Así mismo se ha estudiado el efecto del caudal de regeneración y la concentración del agente regenerante sobre la capacidad de regeneración y la concentración de la corriente rica en nitrógeno. Se observó cómo con la medida de la conductividad es posible determinar la duración de ambas fases. Los datos experimentales, los resultados de los modelos matemáticos y un balance económico sirvieron para determinar las condiciones de operación. 4- Análisis económico y ambiental de las tres alternativas propuestas para identificar las alternativas viables en la mejora de una EDAR existente o construcción de una nueva instalación. En ambos escenarios el proceso de UF resultó ser el principal limitante para la implantación de alguna de las alternativas. Realizando una proyección futura sobre cómo estará esta tecnología en un corto plazo se est / [CA] Els processos convencionals de depuració de l'aigua residual presenten un elevat consum energètic i no permeten una recuperació dels recursos presents en l'aigua. En la transformació de les Estacions Depuradores d'Aigua Residual (EDAR) en estacions de recuperació de recursos, els processos de redirecció de carboni, com la ultrafiltració de l'aigua residual (UF) juguen un paper crucial. Aquesta tecnologia envia tota la matèria orgànica suspesa i part de la soluble (la fracció col·loidal) a la digestió anaeròbia. Després de la filtració, la línia principal d'aigües presenta una composició diferent de la tradicional, un baix ràtio de matèria orgànica per unitat de nitrogen (DQO/N) i està exempt de sòlids suspesos. Aquesta tesi doctoral té com a objectiu estudiar experimentalment, i amb models matemàtics, diferents alternatives de tractament del permeat d'una planta pilot d'ultrafiltració d'aigua residual urbana real per a aconseguir un efluent que complisca amb els requisits d'abocament. Els esquemes proposats permeten aprofitar les infraestructures existents de les EDARs. La tesi està estructurada en quatre blocs: 1- Estudi del procés convencional de nitrificació-desnitrificació (ND). Els resultats experimentals indiquen que el procés de filtració reté una elevada concentració de matèria orgànica i redueix el ràtio el ràtio DQO/N per baix de les condicions estequiomètriques necessàries, que no tot el nitrogen puga ser eliminat amb ND. Pel que per a poder mantindre aquest tractament es necessitari bypasear una part de l'aigua d'entrada el procés de filtració que parteix de l'aigua d'entrada per a ajustar el ràtio DQO/N al valor necessari, o aplicar-lo en aquells influents amb una alta concentració de matèria orgànica soluble, ja que una part d'aquesta fracció no serà retinguda. 2- Avaluació del procés de nitrificació parcial (NP) seguit del procés Anammox. Totes dues etapes biològiques no requereixen de matèria orgànica per a l'eliminació del nitrogen i el seu consum energètic és menor, en reduir les necessitats de ventilació. Experimentalment es va estudiar el procés de NP en la línia principal d'aigües.Reglant la duració de la fase aeròbia mitjançant un controlador basat en el pH i l'oxigen, mantingut una concentració d'oxigen de 0.5 mg O2/L i temps de retenció cel·lular de 3 a 10 dies, es va aconseguir acumular NO2 en el reactor. El model matemàtic va confirmar la importància d'aquests paràmetres d'operació. 3- Concentració del nitrogen mitjançant columnes d'intercanvi catiònic (IC) i recuperació en contactors de membranes (HFMC). Inicialment es va seleccionar el material adsorbent a partir dels resultats de les proves de cinètiques d'adsorció. La zeolita natural, el material triat, es va caracteritzar i es va analitzar la influència dels interferents mitjançant isotermes d'adsorció. També es va analitzar quin regenerant oferia millors resultats. Després, es van realitzar diversos assajos en columnes d'adsorció per a estudiar la influència del cabal de treball i la concentració d'amoni en el influent i d'altra banda, el cabal de regeneració i la concentració de l'agent regenerant. Es va observar com mitjançant amb la conductivitat es pot determinar la duració de totes dues fases. Les dades experimentals, els resultats dels models matemàtics i un balanç econòmic van servir per a determinar les condicions d'operació. 4- Anàlisi econòmica i ambiental de les tres alternatives proposades, amb consideracions ambientals per a identificar les alternatives viables en la millora d'una EDAR existent o construcció d'una nova instal·lació. En tots dos escenaris el procés de UF va resultar ser el principal coll de botella per a facilitar la implantació d'alguna de les alternatives. Realitzant una projecció futura sobre com estarà aquesta tecnologia en un curt termini, es van estimar unes moderades millores tant en el seu cost, operació i rendiment. En aquesta projecció futura l'escenari 1, ND, no aconsegueix aconseguir uns re / [EN] Conventional wastewater treatment processes are energy-intensive and do not allow the recovery of the resources present in the water. On the way towards the transformation of Wastewater Treatment Plants (WWTP) into resource recovery plants, carbon redirection processes, such as ultrafiltration of wastewater (UF), play a crucial role. This technology sends all suspended and part of the soluble organic matter to anaerobic digestion. After filtration, the main water line presents a different characteristic from the traditional one, mainly a low ratio of organic matter per unit of nitrogen (COD/N) and absence of suspended solids. This doctoral thesis aims to study experimentally, and with mathematical models, different alternatives of treatment of the permeate from a real urban wastewater UF pilot plant to achieve an effluent that meets the discharge requirements. The proposed schemes allow to take advantage of existing WWTP infrastructures. The thesis is structured in four blocks: 1- Study of conventional nitrification-denitrification (ND) process. The results indicate that the filtration process retains a high concentration of organic matter and reduces the COD/N ratio below the necessary stoichiometric conditions, causing incomplete nitrogen removal. In order to maintain this treatment, it would be necessary to bypass part of the inlet water to the filtration process, to adjust the COD/N ratio to the necessary value, or to apply this alternative in those influents with a high concentration of soluble organic matter, since part of this fraction will not be retained. 2- Evaluation of the partial nitrification process (PN) followed by the Anammox process. Both biological stages do not require organic matter for nitrogen removal and their energy consumption is lower, as aeration needs are reduced. The PN process was studied experimentally in the main water line. By controlling the duration of the aerobic phase with a pH and oxygen-based controller, maintaining an oxygen concentration of 0.5 mg O2/L and sludge retention times of 3 to 10 days, N-NO2 accumulation in the reactor was achieved. The mathematical model confirmed the importance of these operational parameters. 3- Nitrogen concentration by cation exchange columns (CEC) and recovery in membrane contactors (HFMC). Initially, the adsorbent material was selected based on the results of the adsorption kinetics tests. Natural zeolite, the material chosen, was characterized and the influence of interferents was analyzed by means of adsorption isotherms. It was also analyzed which regenerant provided the best results. Finally, several tests were carried out on adsorption columns to study the influence of the working flow rate and the concentration of ammonium in the influent on the ammonium adsorption capacity and the volume of permeate treated before reaching the breakpoint. The effect of the regeneration flow rate and the concentration of the regeneration agent on the regeneration capacity and the concentration of the nitrogen-rich stream was also studied. It was observed that by conductivity monitoring it is possible to determine the duration of both phases. Experimental data, the results of mathematical models and an economic balance were used to determine the operating conditions. 4- Economic and environmental analysis of the three proposed alternatives to identify viable alternatives in the improvement of an existing WWTP or construction of a new facility. In both scenarios the UF process turned out to be the main bottleneck to facilitate the implementation of any of the alternatives. By making a future projection of how this technology will be in the short term, improvements in its acquisition cost, operating costs and performance were estimated. With this projection, alternative 1, ND, does not achieve appropriate economic returns. Alternative 2, PN + Anammox, shows a better economic balance than the current situation. Alternative 3, CEC + HFMC, as it does not take advanta / Esta tesis se ha desarrollado dentro del marco de trabajo del proyecto ‘Aplicación de la tecnología de membranas para potenciar la transformación de las EDAR actuales en estaciones de recuperación de recursos Proyecto MEM4REC (Código del proyecto: CTM2017-86751-C2-1-R), financiado por el Ministerio de economía, industria y competitividad (MINECO). También esta tesis se ha visto financiada por la ayuda para la formación de profesorado universitario (FPU) (código de la ayuda: FPU17/00540), financiada por el Ministerio de Universidades / Godifredo Calvo, J. (2024). Estudio de la eliminación/recuperación de nitrógeno en el permeado de la ultrafiltración de la línea de aguas de una EDAR mediante eliminación por nitrificación parcial y recuperación con zeolitas [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203439

Irish agriculture is becoming increasingly regulated, with restrictions on fertiliser application rates and stocking rates to reduce nitrate (NO₀⁻) leaching losses. However these regulations have been, to date, based on minimal field research. The purpose of this study was to determine the actual leaching losses of nitrate from Irish dairy pasture at a range of stocking rates, and to investigate the effectiveness of the nitrification inhibitor DCD at reducing nitrate leaching losses where these are deemed excessive. In grazed pastures, a major source of leached nitrate is the urine patch, where a high rate of N is applied in one application. This trial recorded the losses from urine and non-urine areas of pasture separately. Nitrate leaching losses from three soils were recorded using lysimeters at Johnstown Castle, Co. Wexford, over two years. Total nitrate losses were higher from the freely drained Clonakilty and Elton soils than from the heavy Rathangan soil. Mean nitrate losses from urine patches ranged from 16 - 233 kg nitrate-N / ha⁻¹, and were reduced by up to 53% when DCD was applied. DCD also reduced peak and mean nitrate-N concentrations in many cases. In addition, DCD halved the nitrous oxide (N₂O) emission factor on the Rathangan soil, caused increases in pasture N content, and increased herbage yield in some treatments. The distribution of urine patches under dairy grazing was recorded using GPS at Kilworth, Co. Cork. Cows were also found to deposit 0.359 urine patches per grazing hour. A model was produced to predict field-scale nitrate leaching losses from dairy pasture at a range of stocking rates. At 2.94 cows per hectare, the highest stocking rate, annual field N loss was below 34 kg nitrate-N ha⁻¹, mean drainage N concentrations were below 5.65 mg nitrate-N L⁻¹ (the EU drinking water guideline value), and the worst-case-scenario autumn peak concentration did not exceed 21.55 mg nitrate-N L⁻¹ (above the EU Maximum Allowable Concentration (MAC) but below the World Health Organisation (WHO) drinking water limit). DCD reduced total annual field N loss by 21% (a conservative estimate), and also reduced mean and peak nitrate concentrations. Provided fertiliser application rates are at or below 291 kg N ha⁻¹, and based on current legislative values for drinking water quality, this trial does not support any blanket restrictions on the stocking rate of Irish dairy farms. However where particularly high water quality is required, DCD shows potential as a useful tool to achieve low nitrate concentrations.

From the Proceedings of the 1972 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - May 5-6, 1972, Prescott, Arizona / A preliminary study was made with the objective of examining nitrogen species transformations of treated sewage effluent releases within the channel of an ephemeral stream, the Santa Cruz River of southern Arizona. Water quality samples were taken at established locations in sequence so that peak daily flows could be traced as the effluent moved downstream. Results indicate that increased nitrification, coinciding with changing stream characteristics, starts in the vicinity of Cortaro Road (6.3 river miles from the Tucson Sewage Treatment Plant discharge). Through physical-chemical changes in streamflow, nitrate -nitrogen values reach a maximum at approximately 90-95 percent and 60-80 percent of total flow distance for low flows and high flows, respectively. Concentrations of ammonia-nitrogen and total nitrogen decrease continuously downstream with both high and low flows. Therefore, the rate of nitrification within sewage effluent releases in a desert stream channel evidently is related to flow distance and physical characteristics of the stream.

From the Proceedings of the 1978 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 14-15, 1978, Flagstaff, Arizona / Algal growth and oxygen evolution at the soil -water interface of soil recharge basins intermittently flooded with secondary sewage effluent (SSE) produced diurnal fluxes in dissolved oxygen (DO) in the SSE and redox potentials (Eh) in the SSE and the surface soil of the basin. The maximum daily DO-% saturation in the SSE during flooding ranged from 30 to 450 %, depending on the length of flooding and seasonal effects of temperature and solar radiation. Diurnal cycles of Eh in the SSE and the top 0 to 2 cm of soil indicated that oxygen production by algae and bacterial nitrifying and denitrifying reactions at the soil-water interface are occurring daily for limited periods during flooding and that these reactions might contribute to the net-N removal and renovation of SSE by soil filtration.