Polycyclic Aromatic Hydrocarbons (PAHs) in Natural and Anthropogenically Modified Soils (A Review)

Abstract

Technological progress of over than seven-billion population forces an avalanche development of industry, transport and urbanization. The unusual demographic success of the Homo sapiens species has caused very serious environmental impact on abiotic and living organisms. One of the most visible phenomenon of anthropopressure is the increase of environmental contamination of water, air and soil with various xenobiotics, in particular with Polycyclic aromatic hydrocarbons (PAHs) – organic compounds with two or more fused aromatic rings. PAHs are widespread environmental contaminants resulting from incomplete combustion of organics, but partly are of the natural biological and soil-biological origin. PAHs are low soluble in water, but highly lipophilic and easily adsorb on the air particles. PAHs are highly carcinogenic or mutagenic. The assessments of PAHs and their remediation are important. The list issued by the USEPA in 1976 with a view to use chemical analysis for assessing risks to human health, contains a set of compounds of 16 PAHs following criteria of analytical standards availability, occurrence in environment; and toxicity information. The PAHs chemical transformations via destroying double bonds by oxidants are important for safe environment. PAH content in unpolluted soils of various types is relatively low. PAHs are degradable by some microorganisms in the soil. 90 % of PAHs present in environment can be stored in soils, sediments, and sedimentary rocks. PAH content in uncontaminated soils is aroud 100 ppb. In the airport area, due to jet turbine exhaust, the sum of 12 PAHs ranged from 2390 ppb to 7530 ppb. PAH concentration in the town soils is up to 12390 ppb. In the soils of railway junction concentrations of 14 PAHs in 1995 was 2243 ppb, and in 2008 up to 59508 ppb. PAHs concentrations in the soils of coking plant area reache 57921 ppb. The new analytical protocol for determination of PAHs and OPAHs are elaborated. There are many classifications determining the soil pollution degree due to the level of PAH. Poland Institute of Soil Science and Plant Cultivation proposed “sum of 13 PAHs”, Poland Ministry Regulation provides “sum of nine PAHs”, Dutch List contains “sum of ten PAHs”. According every classification, under transport and industries anthropopressure, the soil PAH concentrations are dangerous to human health.