A clean and healthy environment is very important for the existence and further development of the population. However, the development of cities and industrial activities causes environmental pollution by heavy metals, including mercury. The aim of the thesis is to determine the content of mercury in soil and in plants grown in contaminated soil with the addition of alginite. Samples of soil contaminated with mercury were taken from the Malachov and then mixed with alginite in a 1: 3 and 1: 1 ratio. In these substrates, we performed an experiment with Hordeum sativum L. (barley) and Brassica napus L. var. napus (rape). Plant and soil samples were analyzed on a dedicated spectrophotometer - AMA 254. In the samples of substrates used for growing barley we found a mercury content ranging from 0.0761 to 3.5016 mg.kg-1, at a rape from 0.0929 to 2.9085 mg.kg-1. The mercury content in the above - ground barley biomass ranged from 0.0404 to 0.0653 mg. kg-1. In the above - ground rape biomass we measured the mercury content ranging from 0.0425 to 03302 mg. kg-1. The sorption properties of alginite were most pronounced in the above-mentioned rape biomass when a drop in mercury content of 0.2005 mg.kg-1 was recorded. A significant decrease was also observed in the cultivation substrates used for growing barley, where the mercury content by the addition of alginite decreased by 0.20003 mg.kg-1. We compared the resulting values with the limit values that were exceeded in many cases.