Browsing by Subject "ravinnekuormitus"
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(2023)Human-induced nutrient enrichment has led to eutrophication, which is globally a severe environmental problem in aquatic ecosystems. Eutrophication has a variety of deteriorating effects on marine ecosystems in the form of e.g., cyanobacterial blooms, bottom water hypoxia and anoxia, as well as increased fish and benthos mortality. The Baltic Sea is especially prone to eutrophication due to the combined effects of restricted water exchange and extensive nutrient loads. Nutrient enrichment reinforces primary production which further enhances organic matter remineralisation in the sediment – water interface, leading to oxygen depletion in the bottom waters. Decreased oxygen concentrations on the seafloor can lead to the release of phosphorus bound to reducible iron oxides. The so-called ‘vicious circle’ of internal loading is formed through the further enhanced nutrient release from the sediments into the water column due to the reduced bottom water conditions resulting from increased supply of organic matter into the system. However, the processes controlling phosphorus transport from land to sea through the ‘coastal filter’ remain poorly understood. In this study, sediments from Paimionlahti estuary were examined for phosphorus content and bulk elemental composition. Sedimentary phosphorus contents were determined through chemical extractions. The extracted fractions of phosphorus (P) include Fe oxide bound P (Fe-P), authigenic apatite P (Ca-P I), detrital apatite P (Ca-P II), and organic P (org-P). The fraction of Fe-P dominated in the upper sediment layers in most sites, whereas more unreactive fractions associated with P burial remained constant through sediment depth. The generally unreactive forms of P illustrated increasing trends towards open sea areas, partly explained by changes in the overall sediment composition as well as by potential differences in environmental conditions among sampling sites. The highest amounts of Fe-P were recorded in sites with the highest sediment accumulation. The results demonstrate that P from rivers is transformed and processed in the coastal zone, delaying its transport to the open sea.
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(2023)The external nutrient load of the Archipelago Sea weakens the state of the sea. Gypsum is applied to fields in the catchment area because it has been found to reduce phosphorus leaching from fields. Gypsum treatment of fields is organised by the the Centre for Economic Development, Transport and the Environment (ELY) of Southwest Finland through "KIPSI-hanke" (GYPSUM Project). Participation in gypsum treatment is free of charge for farmers. To achieve water protection objectives, more farmers in the area should participate in gypsum treatment. I study what factors that influence the participation of farmers in the catchment area in gypsum treatment of their fields. The underlying motivation for this study was to promote gypsum treatment of fields and improve the state of the Archipelago Sea. My research is a qualitative interview study. My interview data consists of nine farmer interviews. In my analysis, I also use scientific and social research literature and other sources. I compare the interviewees' perceptions of the effects of gypsum with the information presented in the natural science literature. On the other hand, I will unpack social phenomena and events that affect farmers' perception of gypsum treatment and their activities. According to my observations, farmers' participation is influenced by knowledge about gypsum treatment, or the lack of thereof. Also, farmers' perceptions of the effects of gypsum treatment affect their participation decisions. Yield and yield impacts are at the heart when a farmer decides on participation in gypsum treatment, even though gypsum treatment is free of charge for the farmer. Based on my results, farmers' participation in gypsum treatment of their fields is promoted by available solid, experience based, research data on effects of gypsum, especially on the effects on yields. Agricultural advice also proved to be a factor influencing participation in gypsum treatment. At least some farmers would receive information on gypsum treatment of fields as part of other agricultural advice. According to my research, agricultural advisors' knowledge of the effects of gypsum was variable and partly incomplete. According to my research, expert and active gypsum advice would promote participation in gypsum treatment. The historical tensions between rural and urban areas, as well as tension between the implementors and targets of environmental projects, have an impact on farmers' attitudes towards the KIPSI-hanke. From the point of view of the rural population, unjust and top-down environmental projects will also hamper future projects if the design of projects does not consider the involvement of the rural population as participants of the projects, not only as targets of measures.
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