<p>Across the United States corn-belt region substantial quantities of nitrogen (N) fertilizer are applied in both continuous corn (<i>Zea mays</i>L.) and corn grown in rotation with soybean [<i>Glycine max</i>(L.) Merr.]. When compared to continuous corn, corn grown in rotation with soybean typically receives less applied N fertilizer (typically 20-45 kg ha^-1less) than continuous corn due to expected carryover of N from biological N fixation (BNF) by soybean in the preceding year. However, when current N recommendations are followed in both systems, rotational corn has been shown to lose similar or, in some cases, greater amounts of N through subsurface tile lines than continuous corn although the reports in the literature have been inconsistent. In rain-fed systems a key limitation to many previous studies has been an insufficient number of site-years of data to fully characterize management effects across varied environments. Regardless, the development of better management practices to reduce nitrate leaching losses has largely remained focused on managing N applied to corn and soybean’s role in degradation of surface water has been relatively understudied in tile drained agroecosystems. Therefore, the objectives of this study were to use a 23-yr data record to: (1) compare quantities and patterns of N loss in tile drainage water among a soybean-corn rotation fertilized with the recommended preplant N rate, a soybean-corn rotation fertilized with a N reduced rate applied as a sidedress, continuous corn fertilized with the recommended preplant N rate, and an unfertilized, restored prairie as a natural system control, (2) determine whether and when cumulative soybean-corn load losses in drainage water surpassed that of continuous corn, and (3) evaluate the current recommended N credits from the dual perspective of crop productivity and protection of water quality. </p><p> Established in 1992, the Purdue University Water Quality Field Station has continuously assessed field-scale N cycling and losses in tile drains and the N management of the five treatments examined in this study have been maintained since 1995. Treatments were 135 kg N ha^-1applied in rotational corn as a sidedress at approximately V6 each year (CS-135), 157 kg N ha^-1applied preplant in rotational corn (CS-157), and 180 kg N ha^-1applied preplant in continuous corn (CC-180). All corn plots received 23 kg N ha^-1as starter at planting. A restored perennial prairie control with no fertilizer applied (Pgrass) was utilized to compare and discuss the implications of intensively fertilized annual row crops. The 23-yr data record includes N concentration in drainage water, drainflow volume, N load losses in drainflow, grain yield, tissue N concentrations at harvest and N amounts returned to soil in crop residues and removed in grain. </p> Analysis of variance found CS-157 resulted in significantly greater daily flow-proportional N concentrations (23-year mean 11.98 mg L^-1) when compared to all other cropping systems (≤ 10.96 mg L^-1). No reportable significant differences occurred in mean annual drainage flow volume among the respective cropping systems. Annual N load loss was statistically similar among cropping systems, ranging between 9.88 to 12.32 kg N ha^-1yr^-1, and these were all significantly higher than the Pgrass control (1.70 kg N ha^-1yr^-1). When corn and soybean years in rotational systems were analyzed separately for leaching losses, CS-157 was significantly higher than CS-135 and CC-180 (14.70, 10.85 and 11.88 kg N ha^-1, respectively) whereas losses by SC-157 and SC-135 were similar averaging 12.26 and 12.13 kg N ha^-1, respectively. Nitrogen treatment did not impact either corn or soybean mean yields. We concluded that soybean BNF production may be a major driver in N load loss in rotational corn when compared to continuous corn and further reductions in load losses from rotational systems will require a focus on managing soybean-derived N. Lastly, future research should include monthly or seasonal assessment of N load losses to better target practices at vulnerable times of nutrient loss.

High energy consumption in conventional wastewater treatment contributes to a large amount of greenhouse emissions and causes environmental problems such as acid rain and climate change. Many technologies, microbial electrolysis cells (MECs), electrodialysis (ED), and anaerobic digestion (AD), were developed to make wastewater treatment more efficient and economical. This thesis investigated novel MECs and ED to decrease energy consumption in wastewater treatment and recover resources from wastewater. In addition, inhibition of ammonia and acetic acid on high-solid AD was examined in this research. The multi-electrode stack design was applied in MECs to treat municipal wastewater. Rapid organic removal and minimized biosolids production were observed in the stacked MECs. In addition to municipal wastewater treatment, MECs can also recover/remove heavy metals from industrial wastewater. Various removal/recovery mechanisms of toxic heavy metals were discussed in this thesis. ED with bipolar membranes (BPMs) was examined to produce high-purity ammonium sulfate from real wastewater steams. This examination indicates valuable nutrients resources (e.g., ammonium sulfate) can be recovered from wastewater and used as land fertilizers for food production. Membrane scaling problems were also evaluated in ED systems since the formation of inorganic scalants can affect the efficiency of nutrients recovery significantly. In addition, the inhibition of ammonia and acetic acid on AD performance was incorporated in a modified anaerobic digestion model (ADM) for reliable simulation of individual biological reactions in high-solid AD. This research contributes to the body of knowledge by developing wastewater treatment technologies with less energy consumption and biosolids production. The reduction of energy consumption and biosolids production can reduce fossil fuel combustion and waste disposal. Resources, such as ammonia and heavy metals, can be recovered and reused by using the investigatory technologies. Therefore, with these developed technologies, wastewater treatment meets the goal of sustainable development and helps to establish a new green circular economy. / Thesis / Doctor of Philosophy (PhD) / High energy consumption is a main challenge in wastewater treatment. However, a large amount of energy in wastewater can be recovered and reused. The recovery of energy from wastewater can reduce energy costs, save resources, and protect the environment. This research aims to develop novel wastewater treatment technologies to save energy by recovering nutrients and producing biogas from wastewater. Bioelectrochemical systems are used to produce hydrogen gas and recover heavy metals from municipal or industrial wastewater. Electrodialysis systems are applied in ammonia recovery and fertilizer production. Anaerobic digestion systems are employed to produce methane gas as a renewable energy source from wasted sludge. These technologies reduce energy consumption in wastewater treatment and help to establish a new green circular economy for resource recovery.

No description available.

Great advances have been made in the last 100 years in the effort to provide safe and reliable potable water. Unfortunately, organisms surviving the water treatment process still cause illnesses in the population. Acanthamoebae are ubiquitous in the environment and are resistant to commonly used disinfection methods. In addition to being pathogenic on their own, Acanthamoeba spp. are capable of acting as a host to pathogenic bacteria in potable water. The amoebae provide the bacteria with protection from chemical and physical means of disinfection. In this way many pathogens that would otherwise be killed in the water treatment process survive and are capable of infecting water customers. Most likely due to experimental limitations discussed herein, the concentration of organic carbon in solution was not found to affect the number of Acanthamoeba polyphaga surviving within reactors designed to model residential water tanks. A copper ion concentration of 1.3 mg/L was determined to be an effective disinfectant against A. polyphaga trophozoites, while free chlorine at 10 mg/L and monochloramine at 50 mg/L were deemed effective against trophozoites. Sulfate-reducing bacteria (SRB) are suspected to be causative agents in copper pitting corrosion. SRB have been found in tubercles covering pits in many homes experiencing pinhole leaks, but the mechanisms of the survival of these organisms in potable water systems are poorly understood. Nutrient studies conducted show that the absence of nitrogen in solution may encourage copper corrosion by SRB. In addition, a medium specifically designed to encourage SRB growth resulted in a large increase in copper corrosion as compared to the control water. / Master of Science

Periphyton was monitored monthly at four sites on the Waipara River from July 1999 to January 2002. Interactions with river flows, nutrients and invertebrates were examined to determine how these factors controlled periphyton development. Comparison of the Waipara River to other New Zealand streams indicated that periphyton biomass at the uppermost site (Site 1) was generally low to moderate. Further downstream, moderate to high biomass occurred at sites 2 and 4. Biomass at Site 3 was generally low, although some very high values occurred on occasions. Periphyton biomass at sites 2 and 4 exceeded periphyton guidelines for the protection of aesthetic/recreational values at least once during each full year monitored. In contrast, the guidelines were rarely exceeded at Site 1. Dissolved inorganic nutrients were generally poor indicators of the nutrient status of the river because of plant uptake. Cellular N and P values indicated nutrient enrichment at sites 2 and 4, which correspondingly had the highest biomass values. Conductivity tended to positively correlate with temporal and spatial patterns in periphyton biomass and was useful as a surrogate indicator of nutrient supply regimes. It correlated negatively with river flows, indicating higher nutrient concentrations may occur during reduced flows. Notable differences occurred in biomass development between periods of contrasting flow regimes. In particular, annual mean and maximum biomass at the three downstream sites was considerably higher during a period of low stable flows compared to a period of higher base flows. However, at the uppermost site, differences in biomass between these periods were much less pronounced. Invertebrate densities increased significantly with increasing periphyton biomass at the three downstream sites. There was little indication that invertebrates had any major control on periphyton biomass at these sites. However, at the uppermost site, although the invertebrate densities were generally much lower than at the other sites, they are more likely to have a controlling influence on periphyton biomass. Overall, the nutrient supply regime of the Waipara River is the primary controller on biomass development. Flow regimes (both frequency of disturbance and extent of low flows) operate as secondary controls of biomass.

No description available.

Investigations are described which were carried out to analyse the way in which certain mineral element deficiencies restrict the growth and development of plants. The plant system used in this work was excised pea roots grown in sterile culture media, and the deficiencies studied were those of iron, magnesium and molybdenum. Growth was measured at the cell level and related to other characteristics of the system; two different experimental designs being employed to assess the effects of deficiencies. In the first, roots were grown in full nutrient and in deficient media and growth was measured on samples taken after growing periods of 0, 3, 5, 7, 9 and 11 days; while in the second, roots were grown for 7 days in full nutrient and in deficient media and serial one centimetre sections taken from these roots were compared. The first approach assessed the effects of the deficiency on overall growth, and the second gave an indication of the effects of the deficiency on the longitudinal differentiation of pea roots. Both experimental approaches were employed when examining iron and magnesium deficient roots, but only the second when examining molybdenum deficient roots. Roots deficient in iron and magnesium were obtained by culturing tips cut from germinated seeds in deficient media, but two successive tip passages were necessary to obtain roots deficient in molybdenum. Growth was assessed basically in terms of length, cell volume, protein nitrogen, and rate of oxygen uptake. However with iron deficient roots measurements of invertase activity, sensitivity of the oxygen uptake to cyanide, and the frequencies of cells in the different stages of division were also made. The techniques involved in the culture of deficient and full nutrient roots, and the analytical techniques are described. It has been shown that iron deficiency markedly affects the growth and development of excised pea roots. Growth in terms of length and cell number per root is stopped after 7 days and no further increases occur between days 7 and 11. Although iron deficiency stops cell division, measurements made at day 7 indicate that this deficiency does not restrict the process of cell expansion. In fact 7 day old iron deficient roots carry larger cells in the terminal centimetre than full nutrient roots. By 11 days the iron deficient roots have a pronounced swelling at the terminal end, and it is suggested that this is brought about by an abnormal expansion of the cells in the lateral direction. Some cells containing mitotic figures are present in the tips of 7 and 11 day old iron deficient roots. However there are fewer cells in the division stages of prophase and metaphase and practically no cells in the stages of telophase and anaphase in the deficient roots when comparisons were made with full nutrient roots. The protein nitrogen content of iron deficient roots is lower than that of full nutrient roots at day 7, but there is a considerable increase in both deficient and full nutrient roots between days 7 and 11. The trend of the derived quantity, average protein nitrogen content per cell, is the same in both groups of roots up to day 7, but from day 7 to day 11 it increases sharply in the deficient roots but does not change in the full nutrient roots. This result indicates that cell division was not stopped in the deficient roots by a shortage of protein nitrogen as such. At the day 7 stage the distribution of protein nitrogen along the length of deficient roots is different to that in full nutrient roots. The front sections of the deficient roots contain an increased content and the back sections a decreased content when compared with full nutrient roots. On a per cell basis the situation is the same, as the cells in the front sections of deficient roots have a higher average protein content and those in the back sections a lower content when compared with the cells of full nutrient roots. The accumulation of protein nitrogen in the front sections of iron deficient roots is most probably associated with the cessation of active cell division in the meristem. Evidence is available which suggests that under normal conditions the formation and development of cells in the apex of the root is dependent on substrates synthesised in the mature regions of the root and translocated forward. It is considered that in iron deficient roots precursors of protein are no longer removed by the demands of the meristem and they condense to form protein in the regions adjacent to the apex. Invertase activity per unit protein nitrogen is the same in both full nutrient and iron deficient roots at all stages. Further, there is no difference in invertase activity when the corresponding sections of full nutrient and deficient roots are compared at day 7. It is clear that in this one respect the protein of iron deficient roots is similar to that of full nutrient roots. The rate of oxygen intake per root of iron deficient roots is lower than that of full nutrient roots at the early day 3 stage, but there are large increases in the rates in both deficient and full nutrient roots between days 3 and 11. It is of some significance that iron deficiency clearly reduces the rate of oxygen uptake at a stage before the process of cell division is stopped. On a per unit protein nitrogen basis the rate of oxygen uptake of deficient roots is lower than that of full nutrient roots after day 3. It is suggested that the effects of days 3 and 5 are a direct effect of iron deficiency but the effects at days 9 and 11 are influenced by the fact that cell division stops at day 7. The results from 7 day roots show that the effect of iron deficiency in reducing the rate of oxygen intake per unit protein nitrogen is confined to the front three sections of the root as iron deficiency does not alter the rates in the back three sections. Iron recovery experiments show that iron deficient roots 7, 9 and 11 days old can resume cell division and grow when they are transferred to a full nutrient medium. It is of interest that in these experiments the recovery in terms of an increased rate of oxygen uptake is greater than the recovery in terms of length and protein nitrogen. Experiments in which the rate of oxygen uptake of deficient and full nutrient roots were measured in the presence and absence of cyanide show that in both groups of roots there is a large fraction of the respiration insensitive to cyanide. The activity of this cyanide insensitive system increases considerably from day 3 to day 11 in both the full nutrient and iron deficient roots. Increases, after day 3 in the activity of this cyanide insensitive system, which would not contain iron, account for the large increase in the total rate of oxygen uptake of iron deficient roots between days 3 and 11. The activity of the cyanide sensitive system involved in respiration decreases in both groups of roots between days 0 and 5. It increases from day 5 to 11 in full nutrient roots, but does not increase in deficient roots over this period. That synthesis of a cyanide sensitive system involved in respiration stops at or about the same stage as cell division in iron deficient roots is considered to be highly important. This cyanide sensitive system most probably corresponds to the iron containing cytochrome/cytochrome oxidase system, and there is other circumstantial evidence that this system is important in the process of cell division. It is important to note that the activity of the cyanide sensitive system was the same in the tips of deficient and full nutrient roots at the day 7 stage. It may be that a certain minimum level of activity per cell is necessary to maintain division; a slight reduction stopping cell division completely, but not being capable of detection by the method of measurement.

The emissions associated with food consumption make up approximately 20-30 percent of Scotland’s total greenhouse gas emissions (GHG). Reducing demand for high carbon footprint food products may provide an effective instrument for reducing GHG emissions. However, there is concern that using consumption based taxes may also have negative consequences on nutrition. Therefore, this thesis investigates the likely effect of carbon consumption taxes on GHG emissions and the resulting impact on nutrient consumption. The data used for the analysis are the Scottish part of Kantar Worldpanel data for the UK for the period 2006-2013 along with various sources of carbon footprint and nutrient data. This thesis models a carbon consumption tax which is based on the carbon footprint of the products of interest. The impact of the taxes on demand for food products were measured through the use of demand systems. Two forms of demand systems were used: Almost Ideal Demand System (AIDS) and an Exact Affine Stone Index (EASI) which allow for the estimation of price elasticities based on time series data. These Marshallian price elasticities were then used for estimating carbon footprint and nutrient elasticities which allow for the estimated change in GHG emissions (represented as carbon emissions) and nutrients. The price elasticities were particularly important for identifying the substitutes and complements of the different food products. This is useful as some food products such as poultry have a lower carbon footprint relative to beef products. The results suggest that applying carbon consumption taxes would likely reduce carbon emissions though the reduction is relatively small. The net effect of taxing all major food products would likely reduce emissions by 543,208.75 tCO2e/y which represents approximately five percent of the total emissions in Scotland attributed to food consumption (no land use change considered). However, taxing only meat and milk food products could reduce emissions by approximately 1.6 million tCO2e/y. While this reduction is much larger than when all food products are taxed, it is considered that modelling all the major food products offers a more realistic understanding of how households will change their demand for the different food products. The effect on nutrient consumption with regards to taxing all food products suggests that households with lower socioeconomic status would likely experience some favourable changes in terms of a reduction in sugar and energy. Though a negative distributional effect is likely to occur when considering the decreased consumption of vitamin D and the increased consumption of salt. Therefore, a carbon consumption tax is estimated to reduce food based GHG emissions by a relatively small amount. Despite the mainly positive effect on nutrient intake, policy makers are still likely to be cautious when considering this instrument because of the relatively small (compared to other studies) reduction in GHG emissions.

Esta pesquisa foi desenvolvida na Estação de Tratamento de Esgoto de Cajati, onde o tratamento é realizado por lagoas de estabilização com sistema australiano. Em amostragens de variação nictemeral e sazonal, observou-se estratificação térmica nas duas lagoas, sendo que esta foi mais acentuada em abril. Em todos os períodos, a coluna de água esteve homogênea às 2h e 8h e estratificada às 14h e 20h. A estratificação térmica resultou na estratificação química (pH e oxigênio dissolvido), sendo que ambas as lagoas foram divididas em dois compartimentos: superior, com maiores temperaturas, pH e oxigênio dissolvido, e outro inferior, com comportamento contrário. A lagoa anaeróbia apresentou concentrações de oxigênio dissolvido de aproximadamente 10,0 mg/L, o que resulta em funcionamento inadequado também foi confirmado pelos resultados de clorofila nesta lagoa, que foram semelhantes aos da facultativa e atingiram até 3,5x\'10 POT.3\' \'mü\'g/L em abril e julho. Além disso, as concentrações de nutrientes e coliformes foram baixas no afluente bruto em relação às obtidas na literatura. Os valores de pH estiveram altos para lagoas de estabilização, com máxima de 12,17 em janeiro. Apenas em abril, o pH esteve menor (6,84-9,86), condizente com a literatura e adequado para fermentação anaeróbia. O menor pH e maiores temperaturas obtidos em abril resultaram em melhores eficiências de redução que nos outros períodos. As estimativas de vazão e carga orgânica revelaram que a ETE vem operando abaixo da carga prevista, o que pode influenciar na eficiência do sistema, pois este não terá tempo suficiente para formar comunidade microbiana estável. Não foi possível observar variabilidade vertical padrão das biomoléculas proteínas, carboidratos e lipídeos, nem ao longo do sistema. Observou-se heterogeneidade espacial e vertical entre as concentrações de nitrogênio e fósforo em todo sistema, onde alguns processos puderam ser identificados e estes foram influenciados por temperatura, pH e oxigênio dissolvido. Houve predomínio de cianobactéria (Synechocystis sp) na ETE Cajati, seguido de clorofícea (Chlorella kessleri). Em ambas as lagoas, o predomínio foi de Eubactéria com baixas concentrações de Arquéias. O efluente final esteve de acordo com os padrões de lançamento de efluentes estabelecidos na Resolução CONAMA 357/2005. / This research was developed in the Cajati wastewater treatment plant, where the treatment is carried through by stabilization ponds with australian system. In samplings of nictemeral and seasonal variation, thermal stratification in the two ponds was observed, and this was more accented in April. In all the periods, the water column was homogeneous at 2 a.m. and 8 a.m. and stratified at 2 p.m. and 8 p.m. Thermal stratification resulted in chemical stratification (pH and dissolved oxygen) and both the ponds had been divided into two compartments: superior, with higher temperatures, pH and dissolved oxygen, and another inferior, to the contrary behavior. The anaerobic pond presented concentrations of dissolved oxygen of approximately 10,0 mg/L that results in functioning inadequate confirmed by the results of chlorophyll in this pond. The anaerobic pond had been similar to the facultative one, which had reached 3,5 x \'10 POT.3\' \'mü\'g/L in April and July. Moreover, the concentrations of nutrients and coliforms had been low in the raw affluent in relation to those described in literature. The pH values had been high for stabilization ponds, with maximum of 12,17 in January. In April, pH was minor (6,84-9,86), according to literature and for anaerobic fermentation. The minor pH and greater temperature taken in April had resulted in better efficiencies of reduction that in the other periods. The estimates of outflow and organic load had disclosed that the plant is operating below the design load, which can influence the efficiency of the system, therefore it will not have enough time to form steady microbial community. Vertical and spatial variability was not observed for proteins, carbohydrates and lipids. Vertical and spatial heterogeneity was observed in nitrogen and phosphorus concentrations, where some processes could have been identified and these had been influenced by temperature, pH and dissolved oxygen. There were predominance of Cyanobacteria (Synechocystis sp) followed by Chlorophycea (Chlorella kessleri). In both ponds, there was predominance of Eubacteria with low concentrations of Archeae. The final effluent was in accordance with the established standards of discharge of effluent - Resolution CONAMA 357/2005.

Atmospheric nitrogen deposition to the ocean has more than doubled in the past 150 years due to anthropogenic activity, reaching levels comparable with nitrogen fixation in the subtropical North Atlantic. Previous studies have suggested that atmospherically deposited N may increase export production, decrease surface water phosphate levels, and substantially impact geochemical estimates of nitrogen fixation. This dissertation reports on the magnitude and biogeochemical fate of soluble N and P deposition in the subtropical North Atlantic. Aerosol and wet deposition time-series samples were used to determine the fluxes, sources, and N:P ratios of atmospheric nutrient deposition. Based on the magnitudes of total soluble N and P deposition, atmospheric nutrients are estimated to supply ~10-50% of allochthonous N to the North Atlantic subtropical gyre. Samples gathered in Barbados, the Canary Islands, and Miami indicate that atmospheric N sources are primarily anthropogenic (and thus, increasing) and that P sources are primarily natural (and thus relatively steady). Because inorganic nutrient concentrations in surface waters are in the low nM range, increasing P stress in surface waters may occur as a result of increasing N deposition. This assessment is supported by modeling studies, which also indicate that deposition would enhance surface P depletion. Inorganic N contributes nearly all (85-87%) of atmospherically deposited soluble N; the majority (~60%) of the remaining soluble organic N is comprised of an incompletely characterized pool of volatile basic organic N. Water soluble organic P contributes ~20-50% of soluble P. Because organic P contributes a relatively higher portion of soluble P as compared to organic N, the inclusion of organic matter in deposition estimates could both enhance the expected level of export production and reduce the predicted levels of P stress induced by atmospheric deposition. Further modeling studies indicate that the fate of atmospheric nutrients in the subtropical North Atlantic is controlled by non-Redfieldian processes, and that atmospheric nutrients eventually accumulate in the main thermocline. The research presented here suggests that future increases in atmospheric N emissions could have long-term impacts on surface ocean biology and nutrient cycles in the subtropical North Atlantic.