Ala Lombolo
- One of Sweden's most polluted lakes

The degree of pollution in a sediment is highly connected to its level of organic content. The most reactive part of organic matter in a soil is the amorphous humus, which is also of colloidal size (smaller than 0.001 mm). The amorphous humus origins from decomposition of organic matter by microorganisms. This colloidal organic matter is highly reactive, due to its large specific surface area and good sorption abilities. Colloidal organic material can also act as a catalyser for chemical reactions in the soil. The organic matter has an ability to react with a large variety of pollutants and the occurrence of organic matter in a soil will therefore increase the concentration of pollutants in that sediment. (Burden & Sims, 1999)

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The organic content in the sediments in Ala Lombolo is high due to the fact that it served as a recipient for the untreated municipal sewage up until 1967. This has favored the retention of pollutants and metals in the lake sediments rather than keeping them in dissolution in the water and further transporting them down the water system.