Northern wetlands ecosystems play an important role in the hydrological balance of neighboring areas, where they act as chemical barriers against anthropogenic and technogenic contaminations. Studied region is well known for quantity of peat deposits and the volume of peat resources. Peat can be considered as a highly informative marker for assessing change in environmental conditions. The study presents the results of the first investigation of peat samples, collected from representative ecosystems of northern wetland territories with low anthropogenic impact. Component and element composition of various peat types were studied in a relation to hydrologic, climate and sampling conditions. It was found out that organic and ash contents are more dependent on the type of the bog, than geographic location. Climatic factors are more important for the formation of bitumen. The degradation degree in peat increases proportionally to content of humates. High content of biogenic and lithogenic elements was observed in transition-and low-moor peat. The content of trace elements in peat samples do not depend on the type of the peat. The structural properties of peat were studied by the light microscopy, AFM and dynamic light scattering. It was determined that the conformation of studied peat samples is characterized by elements of asymmetry. The observed particles in the solutions exist in dynamic equilibrium with separated globular macromolecules. The size of these nanoparticles is comparable with the size of the particles of other biopolymers of similar nature. Swelling of peat in liquid water was studied. The relationship between structural specificities, origin of peat and its maximum degree of swelling was found. The degree of swelling can be used as structural-sensitive parameter in further research. (C) 2016 Elsevier B.V. All rights reserved.