Längs den svenska kusten verkar landhöjningen, en process där landet höjs efter den senaste istiden. Mest påtaglig är landhöjningen i Östersjön. Till följd av landhöjningen avsnörs grunda havsvikar från havet och bildar nya sjöar, så kallade flader, gloflader och glon. Målet med denna studie var att undersöka sediment från olika provtagningspunkter i en gloflad i Gårdskärsområdet i Lövstabukten (norra Uppland), för att se hur fördelningen av olika arter av kransalger varierat i glofladen under åren när miljön successivt förändrats. För att undersöka detta har oosporförekomst från kransalger i sediment studerats. I det undersökta området får landhöjningen verka ganska ostört, vilket gör det intressant att undersöka just detta område. Denna undersökning visar att Chara aspera, Chara globularis och Chara tomentosa tidigare funnits i den undersökta glofladen. C. aspera förekom vid samtliga fem provtagningspunkter och under längst tid, medan C. globularis noterades vid två provtagningspunkter och C. tomentosa fanns vid endast en provtagningspunkt och är den art som växt i glofladen under de senaste åren. Inga stora skillnader fanns i sedimentet mellan de fem olika provtagningspunkterna. Färgen varierade från mossigt grön och vattenrik i ytsediment till fast lera i de djupare delarna av sedimentet.

The aim of this literature study is to compare and discuss different fields of paleolimnology, with a focus on three main research areas – eutrophication, acidification, and climate change. Pioneering work and the development of paleolimnological methods around these three areas were reviewed and synthesized. Paleolimnology started out as limnology and paleoecology, but has evolved tremendously over the past decades. Early paleolimnological studies focused on lake ontogeny and mechanics in the catchment such as weathering. The focus eventually shifted to nutrient loadings during the 1960s – 1970s as the debate on human induced eutrophication emerged. The important question to answer was which nutrient was the limiting factor in eutrophication. Acidification was the next topic of investigation during the 1980s – 1990s, and paleolimnology developed methods to infer past pH change based on chironomids and diatom fossils preserved in lake sediment. This research resulted in calibration sets and proxies which can be used to reconstruct past conditions. The paleolimnological community eventually shifted focus in the late 1990s to climate change and began to use lake sediment to reconstruct past climatic trends using multiproxy studies such as diatoms, chironomids and geochemistry. Varved lake sediment offered a much needed terrestrial high resolution option to the ice core records. History plays a fundamental role in all environmental issues and paleolimnology has the ability to provide historical records of past environmental conditions. Paleolimnology will most likely play a key role in management and restoration in the future. As technology and training sets develop, fast and cheap ways to interpret sediment proxies will emerge and maybe even fully automated identification of proxies.

Throughout the last glacial period, massive volumes of icebergs were discharged periodically from the Hudson Strait region during so-called Heinrich (H) events depositing sediments in distinct layers across the North Atlantic as they melted. The objective of this research was to measure and describe sedimentation associated with a meltwater plume discharged during the H1 ice-rafting event (14–19 ka) by examining sediment texture. The H1 layer was sampled in 11 piston cores that cover about 4000 km of the slope between Hudson Strait and the Bay of Fundy and range in water depth from 818–2740 m. Disaggregated inorganic grain size (DIGS) distributions were determined using a Coulter Counter. Additionally, carbonate content and the coarse fraction were measured and DIGS spectra were parameterized using an inverse ?oc model and sorted using entropy analysis. Results suggest that H1 layer sediments were mainly delivered by plume, ice-rafting and turbidity currents. In general, plume deposition was only significant proximally and distal sediments were mainly delivered by ice-rafting. However, the lack of plume deposited sediments distally does not necessarily imply the absence of a plume.

The Cataraqui River, which drains 930 square km of watershed before emptying into the inner harbour of Kingston, Ontario (pop: 113,000), has a long history of anthropogenic use. More than 40 industries have existed within the inner harbour over the last century, and while many of these industries are no longer present, the properties that they operated on remain to the present day as potential sources of persistent contamination. This study examined total mercury (THg) concentrations in depth profiles of 21 sediment cores within the inner harbour. THg in pore waters was measured in some selected cores along with methylmercury (MeHg), and total organic carbon measured as % Organic Matter (OM). Results show that the spatial distribution of THg in the surface sediment is not homogenous; concentrations in surface sediment along the southwestern shoreline, adjacent to the former industrial properties, are significantly greater than the rest of the inner harbour, and above the severe effect limit (2000 μg/kg) guideline for sediment. MeHg was detected in some sediment cores, and was found to have a significant, positive correlation with [THg] in surface sediment. THg in pore water was below detection limits in most cores, indicating possible strong associations with sediments, however OM only showed significant, positive correlations with THg in one core sampled. To determine the sources of Hg to sediments, soils, runoff and storm sewer discharges near high concentration sediments were measured for THg. Hg was not detected in storm sewers, but was detected in terrestrial soil near the Kingston Rowing Club at a concentration of more than 4000 μg/kg. Significant [THg] was detected in runoff draining shoreline soils, indicating that erosion from terrestrial sources may be an ongoing source of Hg to sediment. Since [THg] was correlated to the [MeHg] in surface sediment, reducing the amount of Hg entering the river from terrestrial sources may reduce the amount of bioavailable Hg in sediments of the inner harbour. / Thesis (Master, Biology) -- Queen's University, 2007-11-01 19:12:24.364

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Nutrients in the sediments of Lake Manitoba’s south basin are resuspended regularly due to its shallow, polymictic nature. In 2009 short sediment core samples were used to determine an internal available nutrient load from sediment of 17,533 tonnes total nitrogen (TN) and 167 tonnes total phosphorous (TP). Water samples were collected at the Whitemud River and Assiniboine River Diversion (ARD) to determine the N and P input to the lake, resulting in an estimate of a total point source input of 3,547 tonnes of TN and 1,130 tonnes of TP. Open water samples were collected to determine a suspended content of 9.2 tonnes of TN /km2 or and 1.7 tonnes of TP/km2. The ARD is the largest contributor of TP to the south basin. The internal sediment pool is a significant source of TN, and when the ARD does not operate, the largest input of TP to the south basin.

This study combined sedimentation, sediment chemistry and benthic community data from three Oncorhynchus mykiss cage farms in Ontario, along with a laboratory bioassay to examine the effects of aquaculture waste loading. Waste loading rates, as well as sediment TC, TN, TP and metal (Cu, Zn) concentrations were highest beneath the cage and decreased exponentially with distance. During the 21-day bioassay, Tubifex (Oligochaeta, Naididae), Chironomus (Diptera, Chironomidae) and Sphaerium (Bivalvia, Pisidiidae) were subjected to a gradient of waste loading. Survival and growth of Sphaerium simile was highest at intermediate levels of waste loading. Chironomus riparius growth increased with increasing waste addition. Tubifex tubifex growth increased with exposure to fish waste, compared with the control. Until this study, there were no predictions for thresholds of effect at freshwater cage farms in the literature. The proposed threshold of effect on freshwater benthos is 2.0 - 3.0 g C m-2 day-1.

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Many stream restoration projects, as part of returning a degraded ecosystem to a healthier state, aim to restore aquatic invertebrate populations. Unfortunately, many attempts only „beautify‟ streams without achieving improvements in biodiversity. Lack of connectivity of a restoration site to a regional species pool may explain some failures. I tested this by collecting larval and adult aquatic insects from an agriculturally impacted Canterbury high country stream to evaluate connectivity of the regional species pool. The stream was surrounded by high-quality habitat in an adjacent National Park. Surrounding streams contained diverse assemblages of aquatic insects, but processes in the environment and limitations of in-stream habitat meant their adults did not always arrive at the target. In addition, oviposition habitat for hydrobiosid caddisflies was added to sections of stream and compared to un-manipulated control sections to test oviposition site limitation. The addition of oviposition habitat led to more hydrobiosid egg masses in comparison to control reaches. However, oviposition was also limited by in-stream habitat conditions, particularly the abundance of fine sediments. Sedimentation is a common pollutant in streams and is linked to decreases in habitat, food resources, and invertebrate populations. Moreover, common restoration methods, such as riparian management, have little success at reversing already high sediment levels, and are therefore insufficient to bring improvements to in-stream communities or sought-after habitat conditions. Therefore, after determining sediment was restricting sensitive invertebrate recovery at Riversdale Stream, by adding patches of high quality habitat I experimentally compared the factorial effects of sediment flushing and channel narrowing on sediment removal. Treatments improved habitat and prompted recovery of sensitive invertebrates, but an interactive effect where both flushing and channel narrowing combined created the most improved habitat conditions and the greatest improvements of invertebrate communities. Thus, while habitat improvements are an important part of restoration, features limiting species recovery such as connectivity and sedimentation, are particularly important.