The relative sensitivities of four benthic invertebrates (𝘏𝘺𝘢𝘭𝘦𝘭𝘭𝘢 𝘢𝘻𝘵𝘦𝘤𝘢, 𝘊𝘩𝘪𝘳𝘰𝘯𝘰𝘮𝘶𝘴 𝘳𝘪𝘱𝘢𝘳𝘪𝘶𝘴, 𝘏𝘦𝘹𝘢𝘨𝘦𝘯𝘪𝘢 spp., and 𝘛𝘶𝘣𝘪𝘧𝘦𝘹 𝘵𝘶𝘣𝘪𝘧𝘦𝘹) were determined separately for cadmium, copper, and nickel in 96-hour water-only and in spiked sediment exposures. Survival (LC25's and LC5O's), growth and reproduction (IC25's) endpoints were compared amongst the four species. In the water-only tests, 𝘏. 𝘢𝘻𝘵𝘦𝘤𝘢 is the most sensitive species to cadmium and nickel, with mean LC5O's of 0.013 and 3.6 mg/L respectively, and 𝘊. 𝘳𝘪𝘱𝘢𝘳𝘪𝘶𝘴 is the most sensitive species to copper, with a mean LC5O of 0.043 mg/L. In the spiked sediment exposures, 𝘏𝘦𝘹𝘢𝘨𝘦𝘯𝘪𝘢 spp. is most sensitive species to copper with a mean LC5O in sediment of 93 μg/g and a mean IC25 of 38 μg/g, and 𝘏. 𝘢𝘻𝘵𝘦𝘤𝘢 is most sensitive species to cadmium and nickel, with mean LC5O's of 33 and 67 μg/g respectively and mean IC25's of 10 and 40 μg/g respectively. Overall, 𝘛. 𝘵𝘶𝘣𝘪𝘧𝘦𝘹 is the least sensitive species to all metals tested, and the number of young produced/adult is the most sensitive of the reproduction endpoints for 𝘛. 𝘵𝘶𝘣𝘪𝘧𝘦𝘹. The relative sensitivities reveal that two endpoints, 𝘊𝘩𝘪𝘳𝘰𝘯𝘰𝘮𝘶𝘴 and 𝘏𝘦𝘹𝘢𝘨𝘦𝘯𝘪𝘢 survival, can be used to possibly distinguish between cadmium, copper, and nickel metal toxicity. Species test responses in field-collected sediments from areas contaminated primarily by the above mentioned metals were compared to the determined sensitivities in order to establish the causative agent of toxicity. Sediment toxicity was categorized first by comparing species responses to those established for a reference database. Responses in the field sediment support suspected toxicant in some cases, but not others. Multivariate analyses were used to assess sediment toxicity in the field sites based on the species responses, and these analyses reveal that the test endpoints respond to different environmental variables in ordination space. A comparison of test responses in the field sites to those in reference sites in ordination space reveals 13 of the 15 field-collected sites to be toxic or severely toxic. / Thesis / Master of Science (MS)

This dissertation presents a detailed numerical study using fully three-dimensional Large Eddy Simulation (LES) simulations of the flow and mass exchange processes in straight channels containing one or multiple embayments with vertical spanwise walls on one side corresponding to the presence of groynes in river reaches. The main focus is on identifying, understanding and quantifying the role played by the coherent structures and large-scale motions in the momentum and mass exchange processes within the embayments and between the embayments and the main channel. Of the three configurations that are studied, the first two contain only one embayment, and the water depth in the embayment area is equal to the one in the main channel. The two groynes are fully emerged in the first configuration and fully submerged in the second. This allows the study of the intensification of the flow three-dimensionality and acceleration of the mass exchange processes between the embayment and the channel due to the top interface and associated detached shear layer that are present in the submerged case. In both cases, the mass exchange across the embayment-channel interface is highly non-uniform across the depth. The third configuration corresponds to a straight channel with multiple groynes and is identical to one of the cases studied experimentally in a previous scaled model study. The mean water depth in the embayment area is about half that in the main channel; the width and length of the embayments are large compared to the depth; and the width over length ratio is relatively large such that a one gyre circulation pattern is observed inside the embayments. The model is validated with the experimental data available at the free surface. Even for shallow emerged embayments, most of the contaminant leaves the embayment through the top layer of the channel-embayment interface. The present study shows that 3D LES simulations can clarify several important aspects of flow past groyne fields that are very difficult or expensive to quantify using experimental techniques.

Gävle municipality strives to treat all stormwater that may prevent river and lakes from achieving a good water status under the EU water framework directive. There are three stormwater outflows at Västra vägen in Gävle that discharge untreated stormwater to Gavleån. Gävle municipality has an ambition to clean stormwater as close to the source as possible. The purpose of this study is to conduct a multi-criteria analysis to identify stormwater treatment solutions that are suitable from a technical, ecological, economic and sociocultural perspective. According to EU water framework directive Gavleån does not achieve a good chemical and ecological status because of the presence of contaminates in the river. The alternatives that will be evaluated in the multi-criteria analysis consists of a screen pool, percolation storage and four different types of filters. Except these six solutions a null alternative will be included to evaluate if the situation does not change and the stormwater is not treated as it is today. These seven alternatives will be evaluated by a panel that consists of people who work with stormwater or with matters related to the categories in the multi-criteria analysis. The panel's main priority of categories and criteria is produced by the average value of all participants’ weightings and ratings. The most important category was considered to be the sociocultural perspective and the least important was the technical perspective. The criteria that were considered important for the respective categories were operating and maintenance cost (economic perspective), reduction of pollution (technical perspective), environmental impact, land use (ecological perspective, shared position), and outdoor recreation (sociocultural perspective). The option that received the highest score in the analysis was null alternative followed by the screen pool. That is because the null alternative is considered to have the most positive impact on the socio-cultural perspective, ecological perspective and financial perspective while screen pool scored highest in the technical perspective. The results of the MCA should also be interpreted by different stakeholders' priorities and can be seen in Section 6 in which the scoring of all treatment alternatives are reported. / Gävle kommun strävar efter att rena allt dagvatten som kan försvåra möjligheten att sjöar och vattendrag uppnår en god status enligt EU:s vattendirektiv. Det finns tre dagvattenutlopp vid Västra vägen i Gävle som släpper ut orenat dagvatten till Gavleån. Detta dagvatten har Gävle kommun en ambition av att rena genom ett lokalt omhändertagande så nära källan som möjligt. Syftet med denna studie är att genomföra en multikriterieanalys för att identifiera lösningsåtgärder som kan anses som lämpliga utifrån ett tekniskt, ekologiskt, ekonomiskt och sociokulturellt perspektiv. Enligt EU:s vattendirektiv så uppnår inte Gavleån en god kemisk och ekologiskt status på grund av föroreningar som påträffats under mätningar i ån. Alternativen som kommer att utvärderas i multikriterieanalysen består av en skärmbassäng, perkolationsmagasin samt fyra olika gatubrunnsfilter. Förutom dessa alternativ så inkluderas även ett nollalternativ som avser att ingen förändring sker där dagvattnet inte renas. Dessa sju alternativ kommer att viktas av en viktningsgrupp som består av personer som på olika sätt arbetar med dagvatten eller med frågor som är relaterade till kriterierna i multikriterieanalysen. Viktningsgruppens prioriteringar av kategorier och kriterier framställs genom medelvärdet av alla deltagares betygsättning. Den viktigaste kategorin ansågs vara det sociokulturella perspektivet och den minst viktiga var det tekniska perspektivet. Kriterierna som ansågs viktiga för respektive kategori var drift och underhållskostnad (ekonomiskt perspektiv), reducering av föroreningar (tekniskt perspektiv), miljöpåverkan, markanvändning (ekologiskt perspektiv, delad plats), och rekreation och friluftsliv (sociokulturellt perspektiv). Alternativet som fick högst poäng i viktningen var nollalternativet som blev följt av skärmbassäng. Nollalternativet ansågs ha mest positiv inverkan på det sociokulturella perspektivet, ekologiska perspektivet och ekonomiska perspektivet medans skärmbassäng fick högst poäng under det tekniska perspektivet. Resultatet av multikriterieanalysen ska tolkas efter olika intressenters prioriteringar och kan göras i avsnitt 7 där poängsättningen av alla reningstekniker redovisas.