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To describe the environmental condition of the water, we take samples and analyse them. Sampling must be carried out in the same way and at the same locations over many years to detect when a change occurs.

Environmental analysis of lakes and watercourses

Variables we measure can be different plants, animals, or the chemical properties of the water. Analysing the variables tells us if there have been any changes in the environment. The results are combined to give a complete picture of the ecosystem so that a picture of the state of the water can be created.

Based on the data collected, it is possible to assess whether measured values are low or high compared to the previous period or other areas. This gives us an insight into the state of the environment. This is why it is so important that measurements and sampling are carried out using standardised methods and documented traceability. Then we can also check afterwards that the results are reliable. In this way, we create long time series of measurement data with good comparability both in time and with other laboratories.

We take water chemistry samples, for example, at river outlets to calculate which substances end up in the sea. We also take samples of "unaffected" watercourses to provide a reference for other measurements in affected waters. When we take samples in a lake, two of us have to be present for safety reasons. There is a lot of equipment that needs to be brought because we take several different samples at the same time. Many samples are taken in the middle of the lake. It is important that the samples are taken and handled correctly so that no other factors affect the sample. Within 24 hours, the sample must be on site at our laboratories in Uppsala, either for analysis or preservation. Small differences in the samples must be detected early and we therefore work with instruments that can help us with low detection limits.

The biological samples we take in lakes include phytoplankton and zooplankton because they can tell us how the life in the water works, for example if it is affected by eutrophication. Larger waterplants such as reeds can also show this. In watercourses, we sample diatoms that indicate how the water is affected by acidification, metals, and temperatures as well. Plants living on the shoreline are analysed because they tell us how much oxygen is there. Samples are taken continuously at the same coordinates. The samples are often taken together with the water chemistry samples so that they can be evaluated together and results compared. A lot of equipment is needed to be brought to take the various samples. The samples are preserved at the time of sampling and are then analysed at our laboratory in Uppsala, where we determine which species are present in the sample and how many there are.

We monitor the impact of organic environmental pollutants on surface and groundwater quality, sediments, air and precipitation. Our samples allow us to develop source tracking and early warning systems for occurrence and response.

When examining the impact of agricultural pesticides, we focus on four different areas, each representing a different agricultural region.

Published: 28 June 2023 - Page editor: vattenmiljo-webb@slu.se