Review of the literature suggested possible deficiencies of micronutrients in soils of North Western Zambia. Soil analysis, pot and field experiments were employed to investigate possible deficiencies. The pot experiments investigated how raising soil pH through liming influenced extractable micronutrients and their uptake by plants. Plant Mo and Ca were positively correlated with soil pH, while Mn and Zn were inversely correlated, aggravating the zinc inadequacy on all soils and that for Mn on arenosols. Effects of liming on plant uptakes of micronutrients generally followed the same trends as those on soil extraction. Incubating the soil under grass house conditions was found to influence amounts of extractable micronutrients, increasing most times above their levels before the soil was incubated. Field experiments generally showed that applying micronutrients were beneficial to crop yield only at some sites. Grain yield variables responded variously and were most significantly correlated with overall grain yield. Soil analysis usefully predicted deficiencies of Zn for both maize and soybean. However, predictions for B and Mo were ideal for soybean than maize. Cu also seemed to have been wrongly predicted for soybean. However, plant nutrient concentration was better at predicting nutrient status in relation to grain yield, but the lower limits of the suggested optimal concentration ranges may need to be worked out again. Soybean was found to have more micronutrient latent deficiencies at majority of the sites than maize. One of the characteristics of applied micronutrients was their beneficial residual effects of crop yield. The residual benefit was also noticed on maize when the fertilisers were directly applied to soybeans a season before, suggesting a possibility of crop rotation, thus spreading the costs. Results would suggest changing the current fertiliser recommendations in the region.

Common Carp, (Cyprinus carpio), have long been associated with the degradation of wetlands worldwide. Through their feeding activities they resuspend sediments leading to reductions in the abundance and diversity of submerged macrophytes, and the alteration of water chemistry which can lead to the phytoplankton-dominated state. This study took in Delta Marsh, a freshwater coastal wetland of Lake Manitoba, in Manitoba, Canada. It was the second part of a four-year study in which baseline data were collected in 2001 from ten ponds (1-13 ha) with varying degrees of connectivity to the main marsh and carp-accessibility. I continued to monitor a subset of the control and altered ponds two and three years following their alteration (2003 and 2004); I included new ponds, including one large open bay (20.3 ha). The overall four-year study has shown that the presence of carp is at least partially responsible for the turbid, phytoplankton-dominated state that exists in Delta Marsh, and that carp abundance is an important factor. Ponds previously isolated then exposed to carp activity, particularly in the spring when they were gathered at high densities, shifted to the turbid, phytoplankton-dominated state with few macrophytes, and the removal of carp from ponds led to the clear-water state, though not necessarily an abundance of macrophytes. Due to the complexity of natural ecosystems, the effects of carp were not as predictable as smaller-scale studies would suggest. In my study, water quality, submerged vegetation biomass and algal growth varied both temporally and spatially in carp-accessible and carp-free ponds. Nutrient deficiency among periphyton assemblages was hypothesized to be alleviated by the presence of carp. Using nutrient diffusing substrata, I found that nutrient deficiencies varied from year to year among carp-free and carp-accessible ponds. In 2003 the hypothesis was supported, however, in 2004 two of the carp-free ponds exhibited no-nutrient limitations to periphyton assemblages while N and P co-limitation became prevalent in one carp-accessible pond. Parameters over which there was no control, such as the spatial and temporal distribution of carp, their density within a pond, water depth and unquantified top-down effects, including zooplankton grazing, may have contributed to the variability of the results.

No description available.

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.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references. Also available via the Internet.

Thesis (Ph.D.)--University of Delaware, 2009. / Principal faculty advisors: John L. Gallagher, and Denise M. Seliskar, School of Marine Science & Policy.. Includes bibliographical references.

Thesis (MScAgric)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

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.

Micro-organisms are the most abundant and diverse form of life on Earth. Their ability to tolerate stress has enabled them to colonise many inhospitable environments. Microbial processes alter the chemistry of the environment which has left a lasting mark on the geological record. On the other hand, microbial life is heavily influenced by environmental conditions. Indeed, the history of the Earth is shaped by the co-evolution of microbial and geological processes. This thesis explores how micro-organisms are influenced by their environment, with particular reference to microbial rock habitats. Rock habitats are an interesting system to understand the inter-relationship between microbial life and it's environment as they are relatively simple and very common. Rock-dwelling communities are also exposed to numerous stresses such as surface UV exposure, desiccation, temperature fluctuations, low nutrient availability or toxicity from elements leached from the rocks themselves. Three specific aspects of microbial stress in rock environments are investigated here: 1) The use of rocks as a shield from surface UV radiation stress, 2) The microbial response to chemical changes during water-rock interactions, 3) The effect of simultaneous limitation of more than one nutrient. The first uses exposure facilities aboard the International Space Station to provide empirical evidence that colonisation of the early land masses by phototrophs was not inhibited by high surface UV radiation. The latter studies use quantitative proteomics to investigate the cellular response of a heterotrophic bacterium to nutrient deficiency and element leaching, two common stresses in rock habitats. Together these results further our understanding of the relationship between micro-organisms and rocks, both today and over geological time.

The in-stream water quality model, QUAL2Kw, can provide guidance in watershed management decisions by linking changes in nutrient loads to responses in water quality. This model is particularly useful for determining wasteload allocations, aiding in total maximum daily load analyses, and developing numeric nutrient criteria. Unfortunately, states struggle to balance the data collection and modeling requirements to accomplish many of these water quality management tasks due to limited resources. This commonly results in routine data collection and monitoring efforts that do not satisfy the data requirements for modeling. To address this disconnect, this study presents a data collection and parameter calibration methodology suited to meet general QUAL2Kw modeling requirements. Then, with the goal of identifying a range of numeric nitrogen and phosphorus criteria, this general data collection and modeling strategy was applied to sites throughout Utah. To help automate and test scenarios targeted at tracking effects of loading and response combinations, a nutrient criteria tool was also developed to interface with these QUAL2Kw models. By implementing the tool on these models, input concentrations of ammonium (NH4+) ranging from 10 to 101 µg/L and inorganic phosphorus (PO4-) ranging from 1 to 14 µg/L were found to exceed thresholds of bottom algae, gross primary productivity, and ecosystem respiration. Conversely, NH4+ concentrations above 3,500 µg/L and PO4- above 490 µg/L exceeded dissolved oxygen thresholds of 5-6 mg/L in some applications. Some limitations of using mechanistic models in this manner were identified, including model capabilities (e.g., steady-state versus dynamic), inclusion of appropriate processes, uncertainty in calibrated parameters, and site-specific conditions. Although many problems will require more complex modeling efforts with significantly larger data collection efforts, this approach provides an initial framework that aids in the judicial use of resources to aid in watershed management decisions.