Chapter 2

Pesticides in surface waters and groundwater threaten aquatic communities and human health. Furthermore, sediment run-off from agricultural areas results in accumulation of fine sediments, which overlays the natural riverbed resulting in the loss of habitats, e.g. spawning ground for salmons ([1]).

Mercury from atmospheric deposition ends up in sediments and is again released in case of e.g. flooding into the water cycle and the food chain. This leads to high mercury accumulation in biota, especially fish, which is a risk for fish eating animals and a potential risk for human health.

Run-off from urban areas include a bunch of pollutants from different sources, like heavy metals, plastic particles, pesticides and biocides, which probably enter the water cycle without any treatment, and with various impacts to ecosystems and human health (see section point source pollution). Pollutants from households not connected to sewage systems include biodegradable substances, faecal coliforms but also pharmaceuticals and other particles (see section scattered dwellings).