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京都大学 / 新制・課程博士 / 博士(工学) / 甲第24888号 / 工博第5168号 / 新制||工||1987(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 角 哲也, 教授 田中 賢治, 准教授 竹林 洋史 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(農学) / 甲第23943号 / 農博第2492号 / 新制||農||1090(附属図書館) / 学位論文||R4||N5378(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 神﨑 護, 教授 北島 薫, 教授 舘野 隆之輔 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

På senare år har ett nytt forskningsområde kring mikroskopiska plastfragment i marin miljö,kallat mikroplaster, vuxit fram. Mikroplaster härstammar från antropogena källor somavloppsreningsverk och vid fragmentering av makroplast. Det finns ett begränsat antal studierinom området, särskilt vad gäller svenska vatten, vilket innebär att det finns utrymme för merforskning. För att bidra till forskningen har föreliggande studie undersökt sedimentprover frånlitoralen vid sju olika platser längs svenska västkusten samt ett sedimentprov från djupt vattenvid en av platserna. För att undersöka koncentration och distribution av mikroplaster utfördeskorrelationsanalys längs den svenska västkusten mellan mikroplaster och två variabler;kornstorlek och salinitet. Resultatet visade att högst koncentration av mikroplaster återfannsvid Sveriges västkust norra delar och minskade ju längre söderut proverna togs.Förklaringsgraden R2 = 0, 61 visade stark korrelation mellan koncentration mikroplaster ochhög salinitet, samt fanns en korrelation mellan mikroplaster och grov sand medförklaringsgraden R2 = 0,38. Resultaten bidrar till ökad förståelse för hur mikroplasterdistribueras i marin miljö vid den svenska västkusten. Forskarna uppmanar till flerprovtagningar i havets alla zoner för att bättre förstå hur mikroplaster koncentreras ochdistribueras i marin miljö. / In recent years, a new research field regarding microscopic plastic fragments in the marineenvironment, called microplastics, have emerged. Microplastics derives from anthropogenicsources such as sewage treatment plants and the fragmentation of macro plastic. There are alimited number of studies regarding micro plastics, especially concerning Swedish waters,indicating the need for more research. In this study sediment samples were collected from thelittoral area at seven different locations as well as one sediment sample from a deep sea at oneof the sites. The aim is to investigate the concentration and distribution of microplastics alongthe Swedish west coast. A correlation analysis was performed between microplastics and twovariables; grain size and salinity. The results showed that the highest concentration of microplastics were found at the north part of the Swedish west coast and decreased the farther souththe samples were taken. The results showed a strong correlation between microplastics andhigh salinity R2 = 0, 61, and a correlation was seen between micro plastics and coarse sandwith a R2 = 0.38. The results contribute to the understanding of how micro plastics aredistributed in marine environment along the Swedish west coast. The researchers behind thisstudy calls for sampling of all marine zones to further understand how microplastics areconcentrated and distributed in the marine environment

Stream channels and their corresponding riparian zones are composed of complex spatially and temporally dynamic systems. Changing land-use associated with urbanization has resulted in large shifts in riparian assemblages, stream hydraulics, and sediment dynamics leading to the degradation of the world’s waterways. To combat degradation, restoration and management of riparian zones is becoming increasingly common. However, the relationship between flora, especially the influence of invasive species, on sediment dynamics is poorly understood. This relationship must be studied further to ensure the success of management practices. Three methods were used to monitor erosion and turbidity within the Tookany Creek and its tributary Mill Run in the greater Philadelphia, PA region. To evaluate the influence of the invasive species Reynoutria japonica (Japanese knotweed) on erosion, reaches were chosen based on their riparian vegetation and degree of incision. Methods used to estimate sediment erosion included measuring changes in bank pins, repeated total station transects, and monitoring turbidity responses to storm events. While each method has been used in previous studies to monitor sediment flux, the combination of methods in this study allowed their applicability to be compared. Measurements taken with YSI turbidity loggers showed large fluctuations in turbidity based both on riparian conditions and geomorphic positioning, suggesting that future studies need to be careful with logger placement when using sediment calibration curves to estimate sediment yield within streams. There were pros and cons of using both total station and bank pins to estimate bank erosion. Total station has the potential to produce highly accurate measurements but a greater risk of loss of data if the control points used to establish the grid cannot be re-established from one measurement to the next. Bank pins are more likely to influence bank erosion and be affected by freeze-thaw conditions but provide a simple method of monitoring erosion at frequent intervals. Volume calculations based on total station transects along the main stem of the Tookany did not show a consistent relationship between riparian type and erosion rates. However, erosion calculations based on bank pins suggest greater erosion in reaches dominated by knotweed with 4.7x10-1 m3/m and 8.3x10-2 m3/m more erosion than those dominated by trees at Chelten Hills and Mill Run respectively. Turbidity responses to storm events were also higher (76.7 v 54.2 NTU) in reaches with knotweed, although this increase was found when the reach dominated by knotweed was also incised. Thus, this study linked knotweed to increased erosion using multiple methods. / Geology

<p> The legacy of disposal practices for radioactive and other heavy metals has resulted in highly contaminated soils at the INL facility in Idaho Falls. Microbial effects on the mobility of a suite of metals (U, As, Cr, Co and Zn) within INL vadose sediments were assessed over a range of solution metal concentrations and biological activity through batch experiments. Sediment associated metals in the bulk sample as well as individual soil compartments increased as a function of total solution metal concentration. System specific trends in partitioning coefficients emerged, reflecting complex interrelations among biological activity, solution metal concentration and the specific metals involved. </p> <p> Results of this study clearly show that cyclic linkages between metal concentration and biological activity play a role in metal sediment biogeochemical behaviour. Differential impacts of biological activity on metal solid retention as a function of solution metal concentration were observed. This result may reflect feedback of metals on the microbial population such that the extent and/or nature of microbial activity is concentration dependent. Typically biological activity has a stronger effect with increased concentration, changing from a beneficial/neutral impact to an increasingly negative effect across the concentration range. The degree of this effect, and whether positive or negative on soil metal retention was however, element specific and dependent on the degree of biological activity. </p> <p> This is one of the first studies to evaluate the relative affinities of a suite of metals for the solid vs. solution phases over varying metal cocktail concentrations and levels of biological activity. My results indicate that differing affinities occur across this suite of metals, and that their relative affinities are non-linearly dependent on both the levels of metal and biological activity present. These results indicate that successful prediction of metal behaviour in complex natural systems, based on mono-metal laboratory experiments is likely limited. </p> / Thesis / Master of Science (MSc)