The polycyclic aromatic hydrocarbon concentrations in soils in the Region of Valasske Mezirici, the Czech Republic

Many sites in the Czech Republic have been negatively affected by industrial pollution. The town of Valasske Mezirici and its surroundings, in the northeast of the republic, is one of these sites. In the 1960s, a coal tar refinery was established there. Coal tar refineries are known sources of pollution; among the pollutants they produce are various organic compounds, including polycyclic aromatic hydrocarbons (PAHs).The PAHs form a group of chemical compounds that are ubiquitous in the environment [1]. These compounds are well known for their characteristic properties, such as toxicity and carcinogenity, environmental persistence and tendency for bioaccumulation [1-5]. They form through the incomplete combustion or pyrolysis of organic matter, and their release into the atmosphere is connected with energy and heat production, local heating facilities, vehicle exhausts, refuse burning, coke ovens, and so on. They also enter the environment via natural processes such as volcanic activity or forest and prairie fires [6,7]. After being emitted into the atmosphere, they are redistributed between the gas and particle phases, and subsequently deposited to the terrestrial environment through dry or wet deposition [8]. Before being deposited, they can be transported over long distances.Thus, the soil is contaminated with PAHs mainly from atmospheric depositions, directly or via vegetation, or in the case of arable soil with biowaste used as fertilizers [2]. Soil contamination by PAHs is considered to be a good indicator of the level of environmental pollution by human activities [8,9]. It can provide information on regional pollution sources, the long-range transport of PAHs, the rates of pollutant retention and their ultimate destination [10,11].The aim of this paper is to investigate the occurrence of PAHs in urban and agricultural soils that are directly impacted by human activity (urban/agricultural soils) and in forest topsoils in the Valasske Mezirici Region in the Cz