Orientador: Marcelo Carvalho Minhoto Teixeira Filho / Resumo: Inocular sementes de trigo com a bactéria Azospirillum brasilense pode propiciar a fixação biológica de nitrogênio (FBN), porém tem sido observado efeito mais pronunciado desta inoculação no crescimento inicial de plantas, assim, com o sistema radicular mais desenvolvido, a absorção de nutrientes e água pode ser maior. Com isso, o crescimento, produtividade e exportação de nutrientes da cultura do trigo podem ser maiores, porém a resposta a esta inoculacao pode variar conforme a afinidade da bacteria com os cultivares de trigo. Dessa forma, objetivou-se avaliar o acúmulo de matéria seca e extração de nutrientes em estádios fenológicos, exportação de nutrientes pelos grãos, componentes de produção e produtividade de grãos de cultivares de trigo inoculados ou não com Azospirillum brasilense. O experimento foi desenvolvido em Selvíria - MS, em um Latossolo Vermelho Distroférrico de textura argilosa, em sistema plantio direto. O delineamento experimental foi em blocos ao acaso com quatro repetições, com os tratamentos dispostos em esquema fatorial 3 x 2, sendo três cultivares de trigo (CD 116, IPR CATUARA TM e IAC 385), com ou sem inoculação de sementes por Azospirillum brasilense (300 ml ha-1 do produto, com estirpes Abv5 e Abv6 (garantia de 2x108 UFC mL-1). Procedeu-se também a análise de regressão em esquema de parcela subdividida com quatro repetições, em que as parcelas foram constituídas pelos seis tratamentos descritos acima, e as subparcelas no tempo, por sete épocas de c... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

Made available in DSpace on 2015-09-25T12:18:45Z (GMT). No. of bitstreams: 1 IsraelNunesHenrique.pdf: 1394330 bytes, checksum: 72328b064472d745a8632e5b12e4b28c (MD5) Previous issue date: 2006-02-20 / The treated domestic sewer when available for the agricultural activities provides economy of water of good quality and chemical fertilizers and it motivates to the agricultural activities. In the semi-arid area of Brazil the reuse of water can be an alternative for the coexistence with the shortage of the hydric resources. In this context, the rural workers of the Municipal district of Lagoa Seca, PB, that produce vegetables during all year as source of revenue happening of the family agriculture. Several researches were already accomplished with the purpose of developing technologies of treatment of sewers that produces effluents with smaller risks of transmission of diseases, but guaranteeing appropriate concentrations of nutrients to the irrigated cultures. The present study had as objective to evaluate the sanitary aspects and nutricionais of the effluents of treated sewers in a system formed by a reactor UASB followed by polishing pond. The use of those effluents was also verified in the fertigation of bell pepper (Capsicum annuum L.). Compared with treatments of the soil using mineral and organic manuring, the planting of the bell pepper obeyed the statistical planning of blocks random, with 5 treatments and 4 repetitions. During the experimental period weekly analyses of the effluents were accomplished and of the culture of bell pepper. The pos-treatment of the sewer in the polishing pond produced effluent with sanitary quality inside of the values recommended by the World Organization of Health (OMS, 1989) for irrigation of vegetables consumed raw. The bell pepper irrigated with effluent of the reactor UASB didn't present significant difference of productivity (at the level of 5% of probability for the test Tukey), when compared to the application of mineral and organic manuring. / O esgoto doméstico tratado quando disponibilizado para as atividades agrícolas proporciona economia de água de boa qualidade e fertilizantes químicos e incentiva às atividades agrícolas. Na região semi-árida do Brasil o reúso de água poderá ser uma alternativa para a convivência com a escassez dos recursos hídricos. Neste contexto, estão inseridos os trabalhadores rurais do Município de Lagoa Seca, PB, que produzem hortaliças durante todo ano como fonte de renda advindo da agricultura familiar. Diversas pesquisas já foram realizadas com a finalidade de desenvolver tecnologias de tratamento de esgotos que produza efluentes com menores riscos de transmissão de doenças, mas garantindo concentrações adequadas de nutrientes às culturas irrigadas. O presente estudo teve como objetivo avaliar os aspectos sanitários e nutricionais dos efluentes de esgotos tratados em um sistema formado por um reator UASB seguido de lagoa de polimento. Também foi verificada a utilização desses efluentes na fertirrigação de pimentão (Capsicum annuum L.). Comparada com tratamentos do solo utilizando adubação mineral e orgânica, o plantio do pimentão obedeceu ao delineamento estatístico de blocos ao acaso, com 5 tratamentos e 4 repetições. Durante o período experimental foram realizadas análises semanais dos efluentes e da cultura de pimentão. O pós-tratamento do esgoto na lagoa de polimento produziu efluente com qualidade sanitária dentro dos valores recomendados pela Organização Mundial de Saúde (OMS, 1989) para irrigação de vegetais consumidos crus. O pimentão irrigado com efluente do reator UASB não apresentou diferença significativa de produtividade (ao nível de 5% de probabilidade pelo teste Tukey), quando comparado à aplicação de adubação mineral e orgânica.

M. Tech. (Department of Civil Engineering, Faculty of Engineering and Technology), Vaal University of Technology. / Over time, the quality standard of stormwater in the City of Ekurhuleni (CoE) has deteriorated due to industrial, commercial, residential and farming activities. Stormwater quality directly impacts the treatment chain of potable water, and therefore, it should be kept in check at all stages. Innovations in the biofiltration process can provide useful, practical solutions to overcome crucial stormwater pollution problems. In 2013, the CoE developed stormwater design guidelines and standards to be implemented for the design of stormwater management, which include the principles of Water Sensitive Urban Design (WSUD) and Sustainable Urban Drainage Systems (SuDS) in particular. The CoE stormwater design guidelines and standards do not provide details on how the city plans to implement SuDS treatment trains to reduce stormwater pollution experienced by the city. This study aimed to verify the efficiency and effectiveness of vegetated biofilters on the stormwater treatment using CoE – Olifantsfontain's natural stormwater and to determine the most suitable vegetation to be used in the region. The CoE experimental case study was conducted to assess the efficiency of selected vegetated biofilters in lowering the concentration of orthophosphate (PO4-3), ammonium (NH4+), and nitrate (NO3-) from Tembisa/Olifantsfontain stormwater. In the experimental setup, six selected plant species were planted into 30 vegetated biofilter columns, namely: Agapanthus praecox (Dryland plant), Carpobrotus edulis (Dryland plant), Stenotaphrum secundatum (Dryland plant), Zantedeschia aethiopica (Wetland plant), Typha capensis (Wetland plant) and Phragmites australis (Wetland plant). The six species were grouped according to general habitats, i.e. three wetland and three dryland plants. Wetland plants were planted into fifteen vegetated biofilters, and dryland plants were also planted on another fifteen vegetated biofilters. The biofilters contained layers of sandy loam soil, coarse and and gravel sand. Each biofilter had a designated inlet and outlet section fitted with a gate valve to control retention time. The raw stormwater consisting of natural nutrient pollutants was applied to each vegetated biofilter through the inlet section. The samples were collected from the inlet and outlet of the six grouped vegetated biofilters during the month of June. All six plant species reduced outflow concentrations of PO4-3 and NH4+ by an average of 99% and 98%, respectively. The results also show that all plant species excluding Phragmites australis were able to reduce NO3- with outflow concentrations being reduced by an average of 58%. From the results obtained, it may be concluded that all the six plant species may be suitable variants to be applied as biofilter material for the purposes of treating urban stormwater in the CoE. The reason is that the determined removal efficiencies for bio-retention fall within 50% – 60% for PO4-3, and 40% - 50% for NH4+ and NO3- respectively. The results also show that if the plant species were applied for SuDs in the CoE, there could be a great improvement in the urban stormwater quality with the consequent improvement in both surface and groundwater quality of the receiving water bodies in the area. Regardless of the nutrient removal by selected plant species, the inclusion of vegetation in a field setting would slow flow rates and thus encourage infiltration into the soil, improve water quality, and support urban biodiversity. In the CoE, all the selected species could be used in the SuDS treatment trains targeting PO4-3, NH4+ and/or NO3-. The case study results provide a informed records for the CoE in the future/intended application SuDs in the upgrade/rehabilitation of its stormwater system.

<p dir="ltr">In the Midwest, tile drainage is used to lower water tables and remove excess water from the soil to improve crop production. This network of underground pipes (i.e., tiles) and expansive agriculture also increases nutrient export, contributing to ecological harm in local lakes and rivers and further downstream in the Gulf of Mexico. Conservation practices that avoid, control, or trap nutrients can mitigate these losses, but studies quantifying their impact at the watershed scale are challenging. This work uses water quality monitoring data collected throughout the Midwest to identify potential nutrient sources and pathways, the hydroclimatic variables influencing them, and the effects of conservation practices. In a study in northeast Indiana, nutrient travel times for total phosphorus, soluble reactive phosphorus, nitrate, and dissolved organic carbon were observed to be faster during winter storm events, likely due to a lack of vegetative processes. Tile drains were the primary contributor to in-stream nitrogen and phosphorus during spring storms but were not a primary contributor for phosphorus in the winter. Data from nitrate sensors across the Midwest were used to quantify the effect of sampling frequency on hysteresis and flushing indices, showing that sampling intervals greater than 8 hours estimates could lead to inaccurate values, and that caution should be used when interpreting outcomes when using longer sampling intervals. Wet antecedent conditions were associated with a dilution pattern of nitrate during storm events, and tile drainage exacerbates this by causing greater leaching during wet periods. A systematic review of water quality monitoring studies at the watershed scale showed the limits using current data, and suggested how providing better statistics could be used to facilitate a more robust meta-analysis to determine effect sizes and sources of heterogeneity among studies. In a monitoring study located in the central Indiana, agricultural conservation practices reduced nitrate concentrations by 27% in an artificially drained watershed. While tile drainage is a critical pathway for nutrients in the Midwest, the combined effect of various conservation practices can improve water quality at the watershed scale.</p>

Lakes play a major role in the global carbon (C) cycle, despite making up a small area of earth’s surface. Lakes receive, transport and process sizable amounts of C, emitting a substantial amount of the greenhouse gases, carbon dioxide (CO2) and methane (CH4), into the atmosphere. Ice-covered lakes are particularly sensitive to climate change, as future reductions to the duration of lake ice cover will have profound effects on the biogeochemical cycling of C in lakes. It is still largely unknown how reduced ice cover duration will affect CO2 and CH4 emissions from ice-covered lakes. Thus, the primary aim of this thesis was to fill this knowledge gap by monitoring the spatial and temporal dynamics of CO2 and CH4 in ice-covered lakes. The results of this thesis demonstrate that below ice CO2 and CH4 were spatially and temporally variable. Nutrients were strongly linked to below ice CO2 and CH4 oxidation variations across lakes. In addition, below ice CO2 was generally highest in small shallow lakes, and in bottom waters. Whilst below ice CH4 was elevated in surface waters near where bubbles from anoxic lake sediment were trapped. During the ice-cover period, CO2 accumulation below ice was not linear, and at ice-melt incomplete mixing of lake waters resulted in a continued CO2 storage in bottom waters. Further, CO2 transported from the catchment and bottom waters contributed to high CO2 emissions. The collective findings of this thesis indicate that CO2 and CH4 emissions from ice-covered lakes will likely increase in the future. The strong relationship between nutrients and C processes below ice, imply that future changes to nutrient fluxes within lakes will influence the biogeochemical cycling of C in lakes. Since catchment and lake sediment C fluxes play a considerable role in below ice CO2 and CH4 dynamics, changes to hydrology and thermal stability of lakes will undoubtedly alter CO2 and CH4 emissions. Nevertheless, ice-covered lakes constitute a significant component of the global C cycle, and as such, should be carefully monitored and accounted for when addressing the impacts of global climate change.

The main goal of this work has been that of optimizing the operating conditions of a biofilter, intended for the control of methane, an important greenhouse gas widely emitted by older or smaller landfill installations.The specific objectives were: (1) to select a suitable packing material (of organic or inorganic type); (2) to optimize the concentrations of input nutrients, mainly consisting of nitrogen, phosphorus, potassium and copper, which are intended to be introduced via the nutrient solution; (3) to determine the optimized values of the most important design parameters, such as the methane inlet load (which depends on the air flow rate and the inlet methane concentration); and (4) to model the biofilter performance. Firstly, the comparison of the two packing materials, one of organic type, and the other of inorganic type, has revealed that the latter was the more appropriate material for the methane biofiltration. Then, through the use of the selected packing material, the influence of each individual nutrient on the efficiency of the process has been investigated.The results obtained have shown that both nitrogen and phosphorus concentrations have to be controlled, while potassium and copper were revealed as being nutrients of only minor importance. Secondly, the optimization of the inlet gas flow rate and of the inlet methane concentration (and consequently, of the methane inlet load also), has been performed. According to the results of the studies, these parameters require good control during methane biofiltration because a limitation in biofilter performance could otherwise be induced. In addition, it was noted that the increase in the inlet gas flow rate led generally to a greater decrease of the methane conversion than the one induced by the inlet methane concentration. Finally, a new method, based on the use of solid extracts sampled from the methane biofilter, has been applied to the determination of methane biofilter kinetic parameters. Following this study, a steady state model of the methane biofiltration, taking into consideration the important operational parameters, as identified previously, has been developed. One particular feature of this model is that it takes into consideration the influence of the biofilter average temperature.The prediction results, obtained with the use of the model, have been successfully compared with the experimental results.

M. Tech. Agriculture / Leafy vegetables, Swiss chard (Beta vulgaris L. var. cicla), lettuce (Lactuca sativa L.) and mustard spinach (Brassica juncea), are widely grown in South Africa. These leafy vegetables are popular owing to their availability and nutritional properties. Optimisation of crop nutrition is essential to maximize yield and quality of vegetables. Therefore, a study was conducted to evaluate the effect of different levels of nitrogen application on growth and quality parameters of leafy vegetables when grown in a non-circulating hydroponic system. The objective of this study is two-fold: primarily, to determine the influence of nitrogen on growth, yield and overall quality of Swiss chard, lettuce and mustard spinach grown in a non-circulating hydroponic system, and secondly, to determine the effect of nitrogen applications on bioactive compounds and antioxidants, such as antioxidant scavenging activities, ascorbic acid, total phenolics and flavonoids.

Thesis (M.Phil. (School of Public Management and Planning))--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Water and sanitation is one of the key factors in the socio-economic development of a nation and people. Billions of people worldwide do not have access to clean water or basic sanitation leading to many health problems and developmental issues. This article discusses the challenges facing the world, South Africa and in particular the Western Cape and Cape Town in the provision of water and sanitation. For most people the desire is to have access to their own private portable water supply and their own private flush toilet connected via costly bulk water services to sewage treatment plants far away. The question posed is whether this model is sustainable into the future, given the water demands in many parts of the world affected by droughts and more violent weather cycles as a result of climate change and global warming. These factors will affect water supplies in South Africa and in particular the Western Cape and Cape Town. To answer some of the questions raised the Lynedoch EcoVillage development is discussed in detail in terms of sustainable neighbourhood planning and implementation. Sustainable Development is discussed, also various options in terms of applying ecological sanitation. The on-site water and sanitation system of the Lynedoch EcoVillage is discussed as a case study. The results of influent and effluent tests conducted by the CSIR are analysed to see whether the system is conforming to the Department of Water Affairs and Forestry standards for the use of effluent water in irrigation and re-use of water in toilets. Localised models of water and sanitation provision might thus be a way forward to satisfy the increasing demand for such services made on national and local authorities as urban areas increase in size and population.

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Soilless production of crops relies on the addition of high concentrations of nutrients with the irrigation water. The drained nutrient solution should be re-used to reduce the risk of pollution and to increase the water- and nutrient use efficiency of the system. Besides the risk of pathogen build-up, one of the main impediments of a wider application of this method is the frequent analysis required to maintain optimum nutrient concentrations and ratios in the rootzone. Yield reductions may be caused by an unbalanced nutrient solution. Alternatively the addition level of nutrients can be calculated through the use of nutrient uptake models that simulate the change in the re-circulated nutrient solution. To simulate crop water and nutrient demand necessary for model based regulation it was necessary to quantify the key factors affecting nutrient uptake by plants. The nutrient solution concentration and ratios between the macro-nutrients affected the uptake of water and nutrients. The total nutrient uptake per root dry weight increased and more specifically the nitrate (NO3 -), phosphate (H2PO4 -), potassium (K+) and sulphate (SO4 2-) uptake increased with an increase in nutrient solution electrical conductivity (EC) from 0.8 to 4.0 mS cm-1 while water uptake decreased. Except for Ca2+ uptake there was no correlation between nutrient and water uptake. Nutrient uptake can thus not be calculated based on water uptake. Instead a mechanistic high-affinity Michaelis-Menten based model can be used to estimate macro-nutrient uptake (Un, mg m-2 hr-1). Water and nutrient uptake was also affected by the solar radiation levels. Since nutrient uptake is related to the growth rate, solar radiation levels can be expected to influence nutrient uptake. The uptake of all ions increased with an increase in the solar radiation levels and for NO3 -, K+ and H2PO4 - the uptake rate was higher at higher nutrient solution concentrations. The Michaelis-Menten based model was adjusted to incorporate the effect of solar radiation levels on nutrient uptake. Water uptake (Wu, L m-2 day-1) was simulated as a function of crop transpiration and crop leaf area using a linear regression model, but since leaf area development was affected by solar radiation levels this was additionally incorporated into the estimation of the leaf area index (LAI). The composition of the nutrient solution also affected the biomass allocation of the crop which can again affect nutrient use as well as the fruit yield. There was also a direct effect of nutrient solution composition on fruit yield and quality with higher EC’s resulting in smaller fruit but an increase in fruit dry matter %, total soluble solids (TSS), titratable acidity (TA) and lycopene content. The results in this thesis make a valuable contribution to our understanding of the effect of nutrient availability (concentration and ratios) and nutrient requirement for growth (solar radiation levels) on nutrient uptake. Incorporating these into nutrient uptake models resulted in the development of a handy tool to simulate changes in composition of re-circulating nutrient solutions ultimately resulting in an improvement of the water and nutrient use efficiency of soilless systems. / AFRIKAANSE OPSOMMING: Die grondlose verbouing van gewasse is afhanklik van toediening van voedingselemente teen hoë peile in die besproeiingswater. Die voedingsoplossing wat dreineer moet hergebruik word om die risiko van besoedeling te verminder en ook om die water en nutriënt verbruik doeltreffendheid van die sisteem te verbeter. ʼn Ongebalanseerde voedingsoplossing kan ʼn verlaging in opbrengste veroorsaak. Benewens die risiko van patogene wat opbou, is die gereelde analises nodig word vir die handhawing van optimale nutriënt konsentrasies en verhouding tussen elemente in die wortelsone een van die hoof faktore wat ʼn meer algemene gebruik van die metode verhoed. Alternatiewelik kan die nutriënt toedieningspeile bereken word deur voedingstof opname modelle en simulasie van die verandering in water en nutriente wat dreineer. Om ʼn model gebaseerde reguleringsmetode daar te stel was dit nodig om die belangrikste faktore wat nutriënt opname beïnvloed te kwantifiseer. Beide die konsentrasie van die voedingsoplossing en die verhouding tussen elemente het ‘n effek gehad op die opname van water en nutriënte. Die totale nutriënt opname per wortel droë massa het toegeneem. Terwyl water opname afgeneem het met ‘n toename in die elektriese geleding (EG) van die voedingsoplossing vanaf 0.8 tot 4.0 mS cm-1 het die nitraat (NO3 -), fosfaat (H2PO4 -), kalium (K+) en sulfaat (SO4 2-) opname verhoog. Behalwe vir Ca2+ opname was daar geen korrelasie tussen water en nutriënt opname nie. Nutriënt opname kan dus nie bepaal word gebaseer op wateropname nie. Alternatiewelik is die gebruik van ʼn meganistiese hoë-affiniteit Michaelis-Menten-gebaseerde model voorgestel om die opname van makro-nutriente (Un, mg m-2 hr-1) te bepaal. Water- en voedingstofopname is beinvloed deur die ligintensiteit vlakke. Voedingsopname word bepaal deur die groei van die plant, daarom is dit verwag dat ligintensiteit vlakke die opname van voedingstowwe sal beïnvloed. Die opname van al die ione het toegeneem met 'n toename in die ligintensiteit vlakke en die tempo van NO3 -, K+ en H2PO4 - opname was hoër by 'n hoër voedingsoplossing konsentrasie. Die Michaelis-Menten gebaseerde model is aangepas om die effek van ligintensiteit vlakke op nutriënt opname te inkorporeer. Opname van water (Wu, L m-2 dag-1) is gesimuleer as 'n funksie van transpirasie en blaaroppervlakte met behulp van 'n lineêre regressiemodel en aangesien die blaaroppervlak ontwikkeling ook deur ligintensiteit vlakke beïnvloed word, is dit opgeneem in die skatting van die blaaroppervlakte-indeks (LAI). Die samestelling van die voedingsoplossing het die biomassa verspreiding beïnvloed. Dit kan nutriënt gebruik en vrug opbrengs beïnvloed. Die voedingsoplossing samestelling het vrug opbrengs en - kwaliteit beinvloed met kleiner vrugte, maar 'n toename in droëmateriaal %, totale oplosbare vastestowwe (TOVS), titreerbare suur (TA) en likopeen inhoud by ʼn hoër EG. Die resultate in hierdie tesis lewer 'n waardevolle bydrae tot ons begrip van die effek van nutriënt beskikbaarheid (konsentrasie en verhoudings) en voedingstof behoefte vir groei (ligintensiteit vlakke) op voedingsopname. Deur die inligting te inkorporeer in voedingsopname modelle het gelei tot die ontwikkeling van 'n handige instrument om die veranderinge in die samestelling van hersirkulerende voedingsoplossings te simuleer. Dit lei gevolglik tot die verbetering van die water en voedingstof gebruik doeltreffendheid van grondlose stelsels.

The Avon-Heathcote Estuary is of significant value to Christchurch due to its high productivity, biotic diversity, proximity to the city, and its cultural, recreational and aesthetic qualities. Nonetheless, it has been subjected to decades of degradation from sewage wastewater discharges and encroaching urban development. The result was a eutrophied estuary, high in nitrogen, affected by large blooms of nuisance macroalgae and covered by degraded sediments. In March 2010, treated wastewater was diverted from the estuary to a site 3 km offshore. This quickly reduced water nitrogen by 90% within the estuary and, within months, there was reduced production of macroalgae. However, a series of earthquakes beginning in September 2010 brought massive changes: tilting of the estuary, changes in channels and water flow, and a huge influx of liquefied sediments that covered up to 65% of the estuary floor. Water nitrogen increased due to damage to sewage infrastructure and the diversion pipeline being turned off. Together, these drastically altered the estuarine ecosystem. My study involves three laboratory and five in situ experiments that investigate the base of the food chain and responses of benthic microalgae to earthquake-driven sediment and nutrient changes. It was predicted that the new sediments would be coarser and less contaminated with organic matter and nutrients than the old sediments, would have decreased microalgal biomass, and would prevent invertebrate grazing and bioturbation activities. It was believed that microalgal biomass would become similar across new and old sediments types as the unstable new sediments were resuspended and distributed over the old sediments. Contact cores of the sediment were taken at three sites, across a eutrophication gradient, monthly from September 2011 to March 2012. Extracted chlorophyll a pigments showed that microalgal biomass was generally lower on new liquefied sediments compared to old sediments, although there was considerable site to site variation, with the highly eutrophic sites being the most affected by the emergence of the new sediments. Grazer experiments showed that invertebrates had both positive and negative site-specific effects on microalgal biomass depending on their identity. At one site, new sediments facilitated grazing by Amphibola crenata, whereas at another site, new sediments did not alter the direct and indirect effects of invertebrates (Nicon aestuariensis, Macropthalmus hirtipes, and A. crenata) on microalgae. From nutrient addition experiments it was clear that benthic microalgae were able to use nutrients from within both old and new sediments equally. This implied that microalgae were reducing legacy nutrients in both sediments, and that they are an important buffer against eutrophication. Therefore, in tandem with the wastewater diversion, they could underpin much of the recovery of the estuary. Overall, the new sediments were less favourable for benthic microalgal growth and recolonisation, but were less contaminated than old sediments at highly eutrophic sites. Because the new sediments were less contaminated than the old sediments, they could help return the estuary to a noneutrophic state. However, if the new sediments, which are less favourable for microalgal growth, disperse over the old sediments at highly eutrophic sites, they could become contaminated and interfere with estuarine recovery. Therefore, recovery of microalgal communities and the estuary was expected to be generally long, but variable and site-specific, with the least eutrophic sites recovering quickly, and the most eutrophic sites taking years to return to a pre-earthquake and non-eutrophied state. changes in channels and water flow, and a huge influx of liquefied sediments that covered up to 65% of the estuary floor. Water nitrogen increased due to damage to sewage infrastructure and the diversion pipeline being turned off. Together, these drastically altered the estuarine ecosystem. My study involves three laboratory and five in situ experiments that investigate the base of the food chain and responses of benthic microalgae to earthquake-driven sedimen tand nutrient changes. It was predicted that the new sediments would be coarser and less contaminated with organic matter and nutrients than the old sediments, would have decreased microalgal biomass, and would prevent invertebrate grazing and bioturbation activities. It was believed that microalgal biomass would become similar across new and old sediments types as the unstable new sediments were resuspended and distributed over the old sediments. Contact cores of the sediment were taken at three sites, across a eutrophication gradient, monthly from September 2011 to March 2012. Extracted chlorophyll a pigments showed that microalgal biomass was generally lower on new liquefied sediments compared to old sediments, although there was considerable site to site variation, with the highly eutrophic sites being the most affected by the emergence of the new sediments. Grazer experiments showed that invertebrates had both positive and negative site-specific effects on microalgal biomass depending on their identity. At one site, new sediments facilitated grazing by Amphibola crenata, whereas at another site, new sediments did not alter the direct and indirect effects of invertebrates (Nicon aestuariensis, Macropthalmus hirtipes, and A. crenata) on microalgae. From nutrient addition experiments it was clear that benthic microalgae were able to use nutrients from within both old and new sediments equally. This implied that microalgae were reducing legacy nutrients in both sediments, and that they are