The B. Sc. thesis presents the problem of fertilisation with livestock and mineral fertilisers and how they affect groundwater and river ecosystems in the case of nutrient leaching. The paper starts by highlighting the importance of groundwater as a source of drinking water for humans. It also describes the importance of river ecosystems for different organisms such as algae, cyanobacteria, micro-organisms, invertebrates and vertebrates. Later on the processes of making mineral fertilisers are briefly explained, as well as which nutrients are generally found in fertilisers. The advantages and disadvantages of both mineral and livestock fertilisers are listed. The nitrogen cycle is described in more detail below, as nitrate is the most damaging of all nutrients in aquatic systems. Other forms of nitrogen found in nature are also presented. Further more the thesis describes why nutrient pollution occurs in the first place and what we can look out for to minimise nutrient leaching into water systems. It also presents the various environmental changes and consequences that can occur when nitrate concentrations in aquatic systems are elevated (eutrophication, methaemoglobinaemia, release of toxins into water, increased mortality of aquatic organisms such as fish and amphibians, etc. ). At the end, some of the ways we can clean up eutrophic water systems are presented. Among others, the function of the periphyton is described, as well as the possible use of other macrophytes and invertebrates.
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