Phytoplankton across the majority of the world’s oceans are thought to be limited by the availability of either nitrate or iron (Fe). However, the spatial resolution of experiments confirming this is low. Two thesis chapters present the results of bottle enrichment experiments at high spatial resolution across (i) the South Subtropical Convergence (SSTC) in the South Atlantic, and (ii) the Scotia Sea-Drake Passage sector of the Southern Ocean. These studies have added detail to the boundaries of limiting nutrients in these regions. Patterns of Fast Repetition Rate fluorometry (FRRf) derived parameters, physiological regulation of these parameters including influences of community structure, and the environmental controls driving them are analysed. Given its role as an essential micronutrient, there has been much effort in constraining potential sources of bioavailable Fe to the ocean, with one such source receiving recent interest: erupted ash from volcanoes. Bottle-scale ash-incubation experiments alongside conventional iron additions and laboratory ash-leaching experiments were conducted, the results of which suggest phytoplankton would respond strongly to ash deposition in the High Nitrate, Low Chlorophyll (HNLC) areas of the Southern Ocean. Particularly notable was the evidence these experiments provided for potential (co-)limitation of phytoplankton in these waters by the micronutrient manganese. The first three chapters of this thesis highlight a number of biogeochemical implications of trace metal stress, particularly that of Fe stress. Therefore, the ability to map the oceanographic extent of Fe-stressed regions using remote sensing would represent a particularly useful advance in marine biogeochemistry. Theoretically it could be possible to map Fe stress from space using satellite images of chlorophyll fluorescence, yet there are important uncertainties that need to be addressed before this can be carried out. In particular, a better understanding of the midday non-photochemical quenching driven reductions in chlorophyll fluorescence occurring at the time satellite images are captured is required. Analysis of over 200 non-photochemical quenching experiments collected over three research cruises, has allowed us to explore non-photochemical quenching and its relevance for using sunlight induced chlorophyll fluorescence to assess broad patterns of Fe stress. Our results have confirmed that satellite fluorescence quantum yields have the potential to reveal broad regions of Fe stress, however a dynamic non-photochemical quenching correction derived from our experiments and analysis was necessary to achieve this.

The Saudi Arabian government has announced an economic development plan (Vision 2030) to invest in a range of industries across the Kingdom, one of which is the development of aquaculture. In the face of a likely increase in Red Sea fish farming, we investigated the impacts of offshore fish farms on the coastal water quality of the Red Sea by a) measuring the environmental impacts of an operational Red Sea fish farm, and b) testing whether an existing aquaculture modeling software can be used as a meaningful planning tool in the development of Red Sea aquaculture. Water quality parameters such as dissolved oxygen, nutrients, particulate matter, chlorophyll, ammonium, and bacterial abundance were measured seasonally over the course of a year around an offshore fish farm along the south-central coast of Saudi Arabia to determine the impacts of fish farm effluent on the surrounding waters. Bacteria, phosphate, inorganic nitrogen, and suspended particulate matter showed patterns of enrichment close to the fish farm. Additionally, dissolved oxygen has slightly lower concentrations close to and down current from the fish farms. Benthic sediments from a nearby coral reef were also assessed for organic enrichment, but concentrations of total organic carbon and total nitrogen were not significantly different from those at an offshore reef. The data from these sampling efforts were then used as input parameters for an aquaculture modeling software (AquaModel.net), however many of the input parameters required to run the model were unavailable and meaningful conclusions could not be drawn from the results. Through field studies and modeling, we assessed the current impact of a Red Sea fish farm on water quality with the goal of predicting the potential impacts of future offshore aquaculture development in Saudi Arabia.

The annual production of biosolids in the Perth region during the period of this study was approximately 13,800 t dry solids (DS), being supplied by three major wastewater treatment plants. Of this, 70% was typically used as a low-grade fertiliser in agriculture, representing an annual land use area of around 1,600 ha when spread between 5 and 7 t DS/ha. Loading rates of biosolids are typically based on the nitrogen (N) requirements of the crop to be grown, referred to as the N Limiting Biosolids Application Rate (NLBAR). A consequence of using the NLBAR to calculate loading rates is that phosphorus (P) is typically in excess of plant requirement. The resultant high loading rates of P are considered in the guidelines developed for the agricultural use of biosolids in Western Australia, but lack research data specific to local conditions and soil types. Regulatory changes throughout Australia and globally to protect the environment from wastewater pollution have created a need for more accountable and balanced nutrient data. Experiments presented in this thesis were undertaken to ascertain: the percentage relative effectiveness (RE) of biosolids as a source of plant available P compared with inorganic P fertiliser; loading rates to best supply P for optimum crop growth; P loading rates of risk to the environment; and the forms of P in local biosolids. Therefore, both the agronomic and environmental viewpoints were considered. Anaerobically digested and dewatered biosolids produced from Beenyup Wastewater Treatment Plant, Perth with a mean total P content of 2.97% dry weight basis (db) were used in a series of glasshouse, field and laboratory experiments. The biosolids were sequentially fractionated to identify the forms of P present and likewise in soil samples after applying biosolids or monocalcium phosphate (MCP). / The biosolid P was predominantly inorganic (92%), and hence the organic fraction (8%) available for mineralisation at all times would be extremely low. The most common forms of biosolid P were water-soluble P and exchangeable inorganic P (66%), followed by bicarbonate extractable P (19%) and the remaining P as inorganic forms associated with Fe, Al and Ca (14%). Following the application of biosolids to a lateritic soil, the Fe and Al soil fractions sorbed large amounts of P, not unlike the distribution of P following the addition of MCP. Further investigation would be required to trace the cycling of biosolid P in the various soil pools. The growth response of wheat (Triticum aestivum L.) to increasing rates of biosolids and comparable rates of inorganic P as MCP, to a maximum of 150 mg P/kg soil was examined in the glasshouse. The percentage relative effectiveness (RE) of biosolids was calculated using fitted curve coefficients from the Mitscherlich equation: y = a (1-b exp–cx) for dry matter (DM) production and P uptake. The initial effectiveness of biosolid P was comparable to that of MCP with the percentage RE of biosolids averaging 106% for DM production of wheat shoots and 118% for shoot P uptake at 33 days after sowing (DAS) over three consecutive crops. The percentage residual value (RV) declined at similar rates for DM production in MCP and biosolids, decreasing to about 33% relative to freshly applied MCP in the second crop and to approximately 16% in the third crop. The effectiveness of biosolid P was reduced significantly compared with inorganic P when applied to a field site 80 km east of Perth (520 mm annual rainfall). An infertile lateritic podsolic soil, consistent with the glasshouse experiment and representative of a soil type typically used for the agricultural application of biosolids in Western Australia was used. / Increasing rates of biosolids and comparable rates of triple superphosphate (TSP), to a maximum of 145 kg P/ha were applied to determine a P response curve. The percentage RE was calculated for seasonal DM production, final grain yield and P uptake in wheat followed by lupin (Lupinus angustifolius L.) rotation for the 2001 and 2002 growing seasons, respectively. In the first year of wheat, the RE for P uptake in biosolids compared with top-dressed TSP ranged from 33% to 55% over the season and by grain harvest was 67%. In the second year, and following incorporation with the disc plough at seeding, the RE for P uptake by lupins in biosolids averaged 79% over the growing season compared with top-dressed TSP, and by grain harvest the RE was 60%. The residual value (RV) of lupins at harvest in biosolids compared with freshly applied TSP was 47%. The non-uniform placement of biosolids (i.e. spatial heterogeneity) was primarily responsible for the decreased ability of plant roots to absorb P. The P was more effective where biosolids were finely dispersed throughout the soil, less so when roughly cultivated and least effective when placed on the soil surface without incorporation. The RE for grain harvest of wheat in the field decreased from 67% to 39% where biosolids were not incorporated (i.e. surface-applied). The RE could also be modified by factors such as soil moisture and N availability in the field, although it was possible to keep these variables constant in the glasshouse. Consequently, absolute values determined for the RE need to be treated judiciously. Calculations showed that typical loading rates of biosolids required to satisfy agronomic P requirements of wheat in Western Australia in the first season could vary from 0 to 8.1 t DS/ha, depending on soil factors such as the P Retention Index (PRI) and bicarbonate available P value. / Loading rates of biosolids were inadequate for optimum P uptake by wheat at 5 t DS/ha (i.e. 145 kg P/ha) based on the NLBAR on high P sorbing soils with a low fertiliser history (i.e. PRI >15, Colwell bicarbonate extractable P <15 mg P/kg). On soils of PRI <2 mL/g however, biosolids applied at identical loading rates would result in high concentrations of available P. Further work on sites not P deficient would be necessary to validate these findings on farmed soils with a regular history of P fertiliser. The sieving of soil samples used in the field experiment to remove stones and coarse organic matter prior to chemical analysis inadvertently discarded biosolids particles >2 mm, and thus their was little relationship between soil bicarbonate extractable P and P uptake by plants in the field. The risk of P leaching in biosolids-amended soil was examined over a number of different soil types at comparable rates of P at 140 mg P/kg (as either biosolids or MCP) in a laboratory experiment. Given that biosolids are restricted on sites prone to water erosion, the study focussed on the movement of water-soluble P by leaching rather than by runoff of water-soluble P and particulate P. In general the percentage soluble reactive P recovered was lower in soils treated with biosolids than with MCP, as measured in leachate collected using a reverse soil leachate unit. This was particularly evident in acid washed sand with SRP measuring 14% for biosolids and 71% for MCP, respectively, although the differences were not as large in typical agricultural soils. Specific soil properties, such as the PRI, pH, organic carbon and reactive Fe content were negatively correlated to soluble reactive P in leachate and thus reduced the risk of P leaching in biosolids-amended soil. / Conversely, the total P and bicarbonate extractable P status of the soils investigated were unreliable indicators as to the amount of P leached. On the basis of the experiments conducted, soils in Western Australia were categorised according to their ability to minimise P enrichment and provide P necessary for crop growth at loading rates determined by the NLBAR. Biosolids applied at the NLBAR to soils of PRI >2mL/g with reactive Fe >200 mg/kg were unlikely to necessitate P loading restrictions. Although specific to anaerobically digested biosolids cake applied to Western Australian soils, the results will be of relevance to any industry involved in the land application of biosolids, to prevent P contamination in water bodies and to make better use of P in crop production.

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains xi, 145 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 101-104).

Reservoirs are the main drinking water sources in Taiwan. However, about half of 23 reservoirs suffer the eutrophication problems based on the calculated Carlson¡¦s TSI indexes for them. Thus, the reservoir water is seriously polluted. Chen-Ching Lake Reservoir, Fengshan Reservoir, and A-Kong-Tien Reservoir are three major reservoirs that supply water for the domestic, industrial, and agricultural uses in the Kaohsiung area. Due to the long-term sediment deposition at A-Kong-Tien Reservoir, a sediment dredge system is under construction at this reservoir. Thus, only Chen-Ching Lake Reservoir and Fengshan Reservoir play the most important roles in water supply at this moment. However, both Chen-Ching Lake Reservoir and Fengshan Reservoir are in the list of the most eutrophized reservoirs. There are several ways to evaluate the status of eutrophication of reservoirs. The single-index method and multi-variable modeling method are two of the most commonly methods for water quality analysis and eutrophication evaluation for the reservoirs in Taiwan. Based on the analytical results from previous studies, eutrophication results in the fast growing of seaweeds and they spread and cover the whole water bodies, which is called algal bloom. The type of seaweed causing eutrophication in Taiwan reservoirs are mainly Cyanobacteria, especially the commonly found Microcystis. They can not only cause some foul smells but release toxins into the water bodies. That endangers the safety of drinking water and affects the normal water usage. To prevent eutrophication, the nutrients loadings outside and inside of the reservoir areas must be reduced and controlled, which can effectively prohibit the growth of seaweeds. An air-pumping system can also be built for the same purpose. Regular water quality inspection should be carried out to monitor the fluctuation of water quality.

Pyrolysis is the thermo-chemical degradation of biomass in an oxygen-free environment to product liquid, gaseous, and solid co-products. The liquid co-product, known as bio-oil, can be used as a transportation fuel. The gaseous co-product, known as synthesis gas, can be used to power the pyrolysis reactor or other machinery. The solid co-product, known as bio-char, has been studied as an amendment to enhance soil physical and chemical properties and nutrient status. Although previous publications have described the beneficial effects of pyrolysis bio-char on soil physical and chemical properties, relatively little has been published on the recovery of mineral nutrients from pyrolysis co-products. This work quantified the recovery of feedstock nutrients (P, K, Ca, and Mg) and micronutrients (Na, Zn, Fe, Cu, and Mn) from pyrolysis co-products from various feedstocks using three distinct pyrolysis reactor designs. The reactors comprised a laboratory-scale fixed-bed reactor and two fluidized-bed reactors located in College Station, TX and Wyndmoor, PA. Nutrient recoveries, on a feedstock basis, were calculated for a comparison of reactor efficiencies. In addition to nutrient recoveries, physical and chemical properties of input biomass and of bio-char generated by each reactor were characterized through ultimate and proximate analyses. For the fixed-bed reactor, results revealed variation among feedstocks for the recoveries of feedstock sources of macronutrients and Na, Fe, and Cu in pyrolysis co-products. Variation among species was also detected for the recoveries of feedstock sources of P, K, Ca, Mg, and Fe in pyrolysis co-products for samples pyrolyzed using the Wyndmoor reactor. For the College Station reactor, recoveries of feedstock sources of P, K, Ca, and Mg in pyrolysis co-products did not vary among species, but Zn did vary. Ultimate and proximate analyses of biomass and bio-chars generated by the three reactors revealed variation among species. Additionally, the results showed that the recovery of feedstock nutrients varied by reactor design. Statistical analysis revealed high correlations and linear relationships between the recovery of nutrients and reactor mass and energy efficiency and feedstock fiber properties.

Organic wastes like sewage sludge and dairy manure were subjected to microwave enhanced advanced oxidation process ( MW/H₂0₂-AOP). The MW/H₂O₂-AOP was developed to release nutrients like phosphorus and nitrogen in the soluble form from the organic waste; these nutrients could be further recovered and reused. In the past, this process has been successfully applied to a series of organic waste for the purpose of solubilizing nutrients. The objectives of this research were to: (1) improve the MW/H₂0₂-AOP in terms of nutrient release by determining the different factors that influence the treatment, (2) define the factors affecting the process in their order of significance and (3) check the efficacy of the process on various waste. In the MW/H₂0₂-AOP, the role of mixing was verified, using municipal sewage sludge (aerobic and anaerobic). It was speculated that mixing the samples during the process would facilitate uniform heating and thus promote more nutrient release. At a microwave temperature of 80 °C, heating time of 5 minutes and hydrogen peroxide dosage of 1 mL per 1% of total solids, the results showed that mixed samples gave a higher nutrient solubilization compared to the unmixed. Subsequently, mixing and solids concentration were incorporated in a screening design with the other proven important factors viz., microwave temperature and hydrogen peroxide dosage. The results showed that microwave temperature and hydrogen peroxide dosage were the most significant factors for the release of orthophosphate, ammonia and soluble chemical oxygen demand. Preliminary experiments treating anaerobic sludge using MW/H₂O₂-AOP showed a decrease in orthophosphate concentration below the initial untreated value while for ammonia and volatile fatty acids the concentrations remained same as the initial. In this case, the set microwave temperature was 80 °C with 5 minutes heating and hydrogen peroxide dosage of 1 mL per 1% total solids at pH 7. To investigate this behavior, anaerobic sludge was treated at two pH conditions (7.8 and 4) at microwave temperatures ranging from 80 to 160 °C with hydrogen peroxide dosage of lmL per 1% total solids for 5 minutes. The results showed that acid addition helped in the destruction of sludge solids and release of nutrients. TheMW/H₂0₂-AOP was used to treat separated solid dairy manure. Solid dairy manure with total solids 1.6% was subjected to microwave temperature of 120 °C for 10 minutes with a hydrogen peroxide dosage of 2 mL per 1% total solids at three pH conditions (3.5, 7.3 and 12). Only at pH 3.5, substantial quantity of orthophosphate, ammonia, soluble chemical oxygen demands and volatile fatty acids could be released. Further, a screening experiment was designed including microwave temperature, hydrogen peroxide dosage and heating time, to determine the factors most affecting nutrient solubilization from solid dairy manure. Hydrogen peroxide dosage and temperature were important factors in orthophosphate release while microwave temperature and heating time were important in the release of ammonia and volatile fatty acids. The results clearly define the efficacy of the MW/H₂0₂-AOP on various organic waste as well as the conditions under which the treatment can be optimized.

This study focused on the spatial and temporal variation of water qualities and the phytoplankton and zooplankton standing crop of southwestern Taiwan. Data were collected from 30 cruises of research and fishermen vessels between August 1999 and December 2002. The yield of sergestid shrimp in this area was also analyzed for possible relationship with physical environment. Concentrations of phosphate and ammonia in the study area were highest in autumn, while the concentration of dissolved silicon peaked in winter; In spring, the concentration of all three nutrients similarly dropped to their lowest level. Regardless of seasonal variation, the concentration of dissolved silicon positively correlated with the water depth around the year. Positive correlation was found between phosphate and river discharge rates of Kao-Ping River in autumn. Negative correlation was found in spring, summer and autumn for ammonia, negative correlation in spring and autumn for dissolved silicon, respectively. Variations of phytoplankton in seasons and locations were also studied. Chlorophyll a blooms in winter but was at lowest level in summer. Concentration of total-chlorophyll a decreased with distance from the shoreline. Concentration of total-chlorophyll a negatively correlated with the river discharge rate in summer, but was positively correlated in winter. Nanophytoplankton (< 10 £gm) appeared to be the major component of phytoplankton. High standing crop of copepods was found at regions near the Liu-Chiu Yu, the estuary of Kao-Ping River, and near the coast. Significant positive correlation between phytoplankton and Copepoda standing crop indicates possible feeding and grazing relationship between them. Changes of the concentration of chlorophyll a corresponds with relative levels of phosphate and ammonia in some seasons. The period with the highest phytoplanktonic standing crop also coincides with the high yield season of sergestid shrimp (from November to March). Variation of Copepoda standing crop does not follow seasonal changes of phytoplankton. Based on the results from General Linear Model analysis, lunar phases, river discharge rates of Kao-Ping River, and the Fishing Effort (hrs/haul-boat) have significant effects on the yield (kgs/haul-boat) of sergestid shrimp respectively. The yield of sergestid shrimp in the full moon period and the last quarter of a lunar month is higher than other periods. The occurrence of thick thermocline water layer matched with the period of high CPUE of sergestid shrimp.

Eutrophication due to enhanced nutrient concentrations can affect marine communities by altering the species composition of macroalgae and marine invertebrates, where certain species have shown tendencies to increase. The aim with this study was to assess how the species composition changed in relation to the distance from a nutrient enriched stream discharge. The study was conducted in an area with rocky shores and Fucus vesiculosus as the dominant alga, and also included the mouth of the eutrophic stream Kvarnabäcken. Macroalgae and invertebrate abundance was examined in eight locations (including an unaffected reference location) at different distances from the mouth of Kvarnabäcken. The concentrations of total nitrogen and total phosphorus were measured in the marine locations as well as in the stream. Although Kvarnabäcken displayed elevated nutrient concentrations, no distinct nutrient gradient was detected in the marine locations due to distance from the stream. The abundance of invertebrates and macroalgae varied to some extent in the locations, where the location in the immediate mouth area showed most differences, which contributed to the conclusion that the direct impact of nutrient discharge is limited. Although there are aspects indicating that the alterations in animal and algae abundance are consequences of nutrient discharge, other factors that regulate community composition must be considered when evaluating eutrophication in marine communities. / Övergödning kan påverka marina samhällen genom att artsammansättningen av makroalger och marina evertebrater ändras till följd av förhöjda närsalter, bland annat genom att vissa arter tenderar att öka i förekomst. Syftet med denna studie var att undersöka om artsammansättningen av marina evertebrater förändrades i relation till avståndet från ett utsläpp från en bäck med förhöjda närsaltkoncentrationer. Studien utfördes i ett område med klippiga stränder och Fucus vesiculosus som den dominerande algen och inkluderade även mynningen av den övergödda bäcken Kvarnabäcken. Förekomst av makroalger och evertebrater undersöktes i åtta lokaler (en opåverkad referenslokal inkluderad) längs kusten på varierande avstånd från bäcken. Koncentrationerna av totalkväve och totalfosfor mättes i de marina lokalerna och i bäcken. Trots att Kvarnabäcken visade höga halter av närsalter, visade inte resultatet någon tydlig näringsgradient från bäcken, medan det fanns en antydan till förändrad förekomst av evertebrater och alger i lokalerna. Lokalen närmast utsläppet skiljde sig något från övriga, vilket kan indikera att den direkta påverkan av näringstillförsel kan vara begränsat. Därtill är det viktigt att understryka att även om skillnader i förekomst av evertebrater och alger i lokalerna kan bero på närsalter från bäcken måste övriga faktorer tas hänsyn till vid undersökningar av marina samhällen.

Organic wastes like sewage sludge and dairy manure were subjected to microwave enhanced advanced oxidation process ( MW/H₂0₂-AOP). The MW/H₂O₂-AOP was developed to release nutrients like phosphorus and nitrogen in the soluble form from the organic waste; these nutrients could be further recovered and reused. In the past, this process has been successfully applied to a series of organic waste for the purpose of solubilizing nutrients. The objectives of this research were to: (1) improve the MW/H₂0₂-AOP in terms of nutrient release by determining the different factors that influence the treatment, (2) define the factors affecting the process in their order of significance and (3) check the efficacy of the process on various waste. In the MW/H₂0₂-AOP, the role of mixing was verified, using municipal sewage sludge (aerobic and anaerobic). It was speculated that mixing the samples during the process would facilitate uniform heating and thus promote more nutrient release. At a microwave temperature of 80 °C, heating time of 5 minutes and hydrogen peroxide dosage of 1 mL per 1% of total solids, the results showed that mixed samples gave a higher nutrient solubilization compared to the unmixed. Subsequently, mixing and solids concentration were incorporated in a screening design with the other proven important factors viz., microwave temperature and hydrogen peroxide dosage. The results showed that microwave temperature and hydrogen peroxide dosage were the most significant factors for the release of orthophosphate, ammonia and soluble chemical oxygen demand. Preliminary experiments treating anaerobic sludge using MW/H₂O₂-AOP showed a decrease in orthophosphate concentration below the initial untreated value while for ammonia and volatile fatty acids the concentrations remained same as the initial. In this case, the set microwave temperature was 80 °C with 5 minutes heating and hydrogen peroxide dosage of 1 mL per 1% total solids at pH 7. To investigate this behavior, anaerobic sludge was treated at two pH conditions (7.8 and 4) at microwave temperatures ranging from 80 to 160 °C with hydrogen peroxide dosage of lmL per 1% total solids for 5 minutes. The results showed that acid addition helped in the destruction of sludge solids and release of nutrients. TheMW/H₂0₂-AOP was used to treat separated solid dairy manure. Solid dairy manure with total solids 1.6% was subjected to microwave temperature of 120 °C for 10 minutes with a hydrogen peroxide dosage of 2 mL per 1% total solids at three pH conditions (3.5, 7.3 and 12). Only at pH 3.5, substantial quantity of orthophosphate, ammonia, soluble chemical oxygen demands and volatile fatty acids could be released. Further, a screening experiment was designed including microwave temperature, hydrogen peroxide dosage and heating time, to determine the factors most affecting nutrient solubilization from solid dairy manure. Hydrogen peroxide dosage and temperature were important factors in orthophosphate release while microwave temperature and heating time were important in the release of ammonia and volatile fatty acids. The results clearly define the efficacy of the MW/H₂0₂-AOP on various organic waste as well as the conditions under which the treatment can be optimized.