京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21470号 / 農博第2313号 / 新制||農||1064(附属図書館) / 学位論文||H31||N5165(農学部図書室) / 京都大学大学院農学研究科地域環境科学専攻 / (主査)教授 北山 兼弘, 教授 本田 与一, 教授 舟川 晋也 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Eutrophication is an increasing global concern as human effluent saturates lakes with an over abundance of nutrients. Phosphorus, generally being the limiting nutrient, is often the most impactful, allowing cyanobacteria populations to grow out of control leading to harmful blooms that can produce cyanotoxins, anoxic lake conditions, and mass fish kills. Utah Lake, a shallow highly eutrophic fresh water lake located in central Utah Valley, has experienced these harmful algal blooms for the last several years. The internal phosphorus cycle is a significant driver in Utah Lake's eutrophication, as the sediments act as both a sink and a source for phosphorus. Most of the phosphorus originates from external sources, gets captured by the sediment, and then through several physiochemical and biological process, gets released back into the surface water as a self sustaining eutrophication system. To determine the effects of the different physiochemical processes that drive the internal phosphorus system, we incubated 72 total sediment cores taken from two locations, chosen to best represent the lake's chemical and spatial variability, under aerobic, anaerobic, pH=9.5 and pH=7 conditions with various P concentrations (ambient, 0.5X, 2X, 4X) taking water samples at 0, 12, 24, and 72 hours. Dissolved oxygen (DO), pH, soluble reactive phosphorus (SRP), total dissolved phosphorus (TDP), and other major ions were measured for each sample. The highest P sediment release occurred under aerobic conditions, while the highest P sediment uptake occurred under anaerobic conditions. While pH did appear to have a mild effect on P flux, our study showed the lake has a remarkably stable bicarbonate buffer system making it unlikely that pH would contribute significantly under natural settings. Under all conditions the 2X and 4X cores experienced the highest P uptake, but final elevated P concentrations were still higher than initial ambient concentrations, indicating a probable delayed recovery time after external reductions occur.

A mass balance approach was used in an attempt to quantify nutrient flux to the nearshore at the West Coast, Barbados, W.I. Total nitrogen and total phosphorus levels of the groundwater at inland pumping stations and above beach margins, as well as in the water of the nearshore zone and approximately 2 km offshore, were obtained. Nearshore groundwater seepage rates and salinity data were also taken. This study attempted to use this raw data to estimate flushing rates, nutrient loading rates, and nutrient loss rates, to ultimately create a picture of the fate of nutrients as they travel in groundwater into the nearshore zone. Annual loading for the entire West Coast was calculated at 1.46 x 105 kg NO3---N for nitrogen and 1.19 x 103 kg PO4 3---P for phosphorus. Mean nutrient levels in groundwater above the beach margin were estimated at 969.83 muM for nitrogen and 3.63 muM for phosphorus. For nitrogen and phosphorus respectively, these levels were twice and three times higher than at the pumping stations farther inland; and there was also a fourfold and fivefold drop in nitrogen and phosphorus, respectively, in the nearshore zone relative to this groundwater above the beach margin. This indicated that the dense coastal population at the West Coast was adding significant amounts of nutrient to groundwater after it had left the inland pumping stations. There were no patterns of gradation in nutrient concentrations detected within the immediate nearshore, making completion of an accurate mass balance impossible, though indicating that there was significant advection of submarine groundwater offshore, beyond the study zone. This may contribute to the poor health of West Coast reefs, where sewage and fertiliser leaching and runoff are suspected as the primary sources for nutrient input to submarine groundwater to the south and northern parts of the West Coast, respectively.

Fosfor är ett nödvändigt näringsämne inom jordbruket, trots detta är vi på väg att använda upp den fosfor vi har tillgång till i marken. Denna studie har därför valt att fokusera på en stor källa till fosfor som inte tas till vara på i många av dagens samhällen: mänsklig avföring. Många samhällen har genom historien använt mänsklig avföring som en resurs, bland annat som gödsel vid matodling, vilket återför en stor del av fosforn till marken. I dagens samhällen ses mänsklig avföring som någonting oönskat och äckligt. Vad är det som skapat denna ovilja att använda denna källa till fosfor? Varför slutade samhällen använda mänsklig avföring som gödsel vid matodling? Syftet med denna studie är att belysa de anledningar som ligger bakom att människor slutar att använda mänsklig avföring vid odling av mat. En tematisk analys, och utvalda delar av en komparativ analys, har använts för att analysera lämpligt publicerat material. Denna analys har skapat resultatet som sedan har ställts mot studiens teoretiska ramverk vilket inkluderar: människans syn på sin egen avföring, smuts och renhet, och mänsklig avföring som resurs. Studiens resultat tyder på att det främst är en accelererad urbanisering och en modernisering av samhället som leder till att människor slutar att använda mänsklig avföring som gödsel inom matodling. Människans syn på renhet ställs mot synen av mänsklig avföring som en resurs. Valet att använda mänsklig avföring eller ej styrs av den kulturella uppfattningen om vad som är rent och smutsigt. När de negativa associationerna kring mänsklig avföring överväger de positiva så leder det till att människor tar avstånd från mänsklig avföring trots att exkrementer fortfarande skulle kunna användas som en resurs. / Phosphorus is an essential nutrient in agriculture, despite this fact we are well on our way to using up the phosphorus we have access to in the ground. This study has therefore focused on a major source of phosphorus that is not taken into consideration in a vast majority of today’s societies: human excrement. Many countries have used human excreta as a resource throughout history, including as a fertilizer when producing food, which ensured that a major part of the phosphorus was returned to the soil. In societies today human excrement is viewed as something unwanted and disgusting. What is it that makes humans hesitant to use this source of phosphorus? Why did societies stop using human excrement as a fertilizer when growing food? The purpose of this study is to examine the underlying causes for why people stop using human excrement as a fertilizer when producing food. A thematic analysis, combined with selected parts of a comparative analysis, has been used to analyze apt publicized material. This analysis has resulted in the study’s result, which has then been pitted against the theoretical framework for this study. The theoretical framework includes: people’s view of their own excreta, dirt and cleanliness, and human excreta as a resource. The result suggests that it primarily is an increased urbanization and a modernization of society that leads people to stop using human excrement as a fertilizer when producing food. Human perception of purity is pitched against the view of human excrement as a resource. The choice of using human excrement or not is governed by the cultural perception of what is clean and what is dirty. When the negative associations connected to human excrement outweigh the positive, then humans distance themselves from it, even though the excrement could still be used as a resource.

D.Sc. (Freshwater Biology) / Please refer to full text to view abstract

No description available.

Doctor of Philosophy / Department of Agronomy / Ganga M. Hettiarachchi / Although phosphorus (P) is an essential nutrient for the growth of plants, it is one of the most limiting nutrients in terms of availability as a high proportion of applied P rapidly transforms into insoluble forms with low solubility in soils. To further understand the fate of P applied to soils, two separate but related studies using three high P-fixing soil types each were used for which the objectives were to investigate the mobility, availability, and reaction products from two granular and one liquid P fertilizer alone or plus a fertilizer enhancement product. Energy dispersive spectroscopy showed a substantial amount of P remained in the granule following a 5-week incubation. At the end of the 35-day incubation period there was evidence that the fluid fertilizer was superior over the granular sources in terms of enhanced diffusion and extractability of P for three calcareous soils with varying levels of CaCO₃. Phosphorus x-ray absorption near-edge structure (XANES) spectroscopy results in conjunction with resin-extractable P indicated a strong negative correlation between Ca-P solids formed and P extractability, suggesting that degree of Ca-P formation limits P solubility. For the three acidic P-fixing soils the results were complex. In two out of three acid soils, liquid P treatments diffused farther from the application point than the granular treatments. Phosphorus XANES results suggested that Fe-P or Al-P interactions control the overall P solubility. Integration of pH, resin extractable-P and XANES results suggested the P retention mechanism was either dominated by adsorption or precipitation depending on soil pH. More acidic soil conditions favored precipitation. The objectives of the third study were to observe how long-term (14 years) addition of P with or without N influences the inorganic and organic P pools in a native grassland soil using sequential fractionation, XANES, and ³¹P-nuclear magnetic resonance (NMR) spectroscopy. The overall results suggested that P and N fertilization and associated changes in plant productivity induced significant changes in soil P pools such as Ca-P, phytic acid, monoesters, and residual forms of P. The addition of P alone induced formation of inorganic P forms while the addition of P and N induced transformation of residual P forms into more labile and/or organic P forms.

Marine microorganisms play a significant role in the cycling of nutrients in the open ocean through production, consumption, and degradation of organic matter (OM). Carbon (C), nitrogen (N), and phosphorus (P) are essential ingredients in every known recipe for life. However, the cycling of each of these elements proceeds at different rates such that the ratio of C:N:P can vary widely between particulate, dissolved, organic, and inorganic pools. To better understand the mechanisms controlling these transformations, this study investigated the bacterial remineralization of photosynthetically-derived organic matter derived from cultures of Trichodesmium IMS101, Thalassiosira weissflogii, Prochlorococcus MED4, and particulate material collected from the surface waters of an upwelling regime. Experiments were conducted at sea for a short duration (<6d) and in the laboratory for longer periods (<150 days). In all treatments, across experiments, we observed rapid and selective P remineralization independent of the type of organic material added. Full solubilization and remineralization of P typically occurred within a week. Conversely, N remineralization was slower, with only 39-45% of particulate N (PN) remineralized in shorter (6d) experiments and 55-75% of PN remineralized in <150d experiments. Nitrification was observed after 70-98 days depending on the remineralizing bacteria (isolated from either the Oregon coastal upwelling regime or the North Pacific Subtropical Gyre (NPSG). Notably, these events did not transform the full complement of ammonium to nitrate. This differential lability between N and P led to rapid changes in the N:P ratio of inorganic pools as organic matter was depolymerized by varying bacterial populations. The variable input of potentially limiting elements could have consequences for primary productivity and particle export. Finally, we observed that in short-term experiments with heterotrophic bacteria collected from the NPSG, the N:P ratio of remineralization (11 ± 2.2) was independent of the N:P of added organic material (5-23). This uniformity of inorganic ratios implies differential lability and N:P composition of residual semi-labile and refractory organic matter. Formation of refractory C and N rich organic matter, often termed the microbial pump, is a significant pathway for the transport and sequestration of elements in the aphotic zone of the ocean interior. The experimental results reported here suggest that differential supply of POM leads to rapid and preferential P remineralization, N:P remineralization independent of the N:P of added substrates, and variable N:P of residual organic matter. These findings help constrain our knowledge of elemental cycling in the marine environment. / Graduation date: 2013

Thesis (M.S.)--Indiana University, 2007. / Department of Earth Sciences, Indiana University-Purdue University Indianapolis (IUPUI). Advisor(s): Gabriel M. Filippelli, Catherine Souch, Lenore P. Tedesco. Includes vitae. Includes bibliographical references (leaves 80-83).

All life forms require the nutrient phosphorus and it cannot be substituted by any other element. The global cycle of phosphorus is special among the major biogeochemical cycles, since it has no significant gaseous compounds and only closes every 10-100 million years. However, human activities, as application of mineral fertilizers, conversion of natural ecosystems to arable land and releases of untreated waste, intensify remarkably thephosphorus flows. The problems with linear flows of a limited resource leading to eutrophication of aquaticenvironments, for instance, have generated national environmental quality objectives for phosphorus in Sweden. The main objective of this master thesis is to get a holistic overview of how phosphorus is moving through Gothenburg today, using Material Flow Analysis as method. The spatial system boundary is the municipality of Gothenburg and the temporal system boundary is the year of 2009. One way of dealing with the linear flows ofphosphorus might be to develop the wastewater systems used in Gothenburg today. Possible changes in phosphorus flows, if kitchen grinders or urine-diverting toilets were installed in Gothenburg, are evaluated. In order to make the phosphorus management more sustainable, the linear flows have to be closed to a larger extent than today. One way towards this ambition is to emphasize other fertilizers than the mineral ones, like urine and low-contaminated sludge. The MFA shows that the absolutely largest input of phosphorus to Gothenburg is via the food. The two large outputs of the same magnitude are the digested sludge from the wastewater treatment plant of Rya and the ashes from the waste-fuelled district heating power plant of Sävenäs. About 7% of the phosphorus input to Gothenburg continues into the aquatic environment. According to this study, urine diversion and separate collection of food seem prospective in order to decrease the phosphorus flows in digested sludge from the wastewater treatment plant, ashes and aquatic deposition. An additional advantage would be generation of recycled fertilizing products with good quality. / Näringsämnet fosfor är nödvändigt för alla levande organismer och kan inte ersättas av något annat grundämne. Den globala fosforcykeln är speciell då den inte innehåller några gasformiga föreningar och sluts var 10-100 miljonte år. Användning av konstgödsel, omvandling av tidigare orörda ekosystem till odlingsmark och utsläppav förorenat avfall är exempel på mänskliga aktiviteter som intensifierar fosforflöden. Problemet med att linjäraflöden av denna begränsade resurs leder till övergödning av vattenmiljöer har genererat nationella miljömål i Sverige för fosfor. Det huvudsakliga målet med detta examensarbete är att få en översikt av hur fosfor rör sig genom Göteborg idag med hjälp av substansflödesanalys. Den rumsliga systemgränsen är kommungränsen för Göteborg och den tidsmässiga avgränsningen är året 2009. Ett sätt att förbättra de linjära fosforflödena kan vara att utveckla deavloppssystem som idag används i Göteborg. Förändringarna som uppstår i fosforflödena vid installation av urinsorterande toaletter alternativt köksavfallskvarnar undersöks. Linjära flöden måste bli återcirkulerade i en högre utsträckning än idag ifall fosforhushållningen ska gå mot hållbarhet. Ett sätt att nå denna ambition är att lyfta fram andra gödselprodukter än konstgödsel, exempelvis urin och renare slam. Flödesanalysen visar att det definitivt största inflödet av fosfor till Göteborg är via livsmedel. De två största fosforutflödena, båda i samma storleksordning, är rötat slam från Ryaverket och aska från sopförbränningsanläggningen Sävenäs. Cirka 7% av den fosfor som flödar in i Göteborg fortsätter vidare ut i vattenmiljön. Enligt denna studie verkar urinsortering och separat insamling av matavfall vara goda lösningar för en framtid med mindre fosfor i slammet från Rya och i aska samt till vattenmiljön. En ytterligare fördel skulle vara erhållandet av hållbara gödselprodukter med god kvalitet. / <p>This master thesis has also been published as a technical report at Chalmers with Report No. 2011:124.</p>