Effects of polycyclic aromatic hydrocarbons (PAHs) from different sources on soil enzymes and microorganisms of Malus prunifolia var. Ringo

Abstract

ABSTRACT The main components of polycyclic aromatic hydrocarbons (PAHs) and the degree of contamination of soil with different oils (gasoline, diesel oil, and lubricating oil) were examined. Malus prunifolia var. Ringo was planted in soil contaminated by gasoline, diesel oil, or lubricating oil with three different concentrations which were low concentration (0.1 g kg−1), medium concentration (0.2 g kg−1), and high concentration (0.5 g kg−1) in April 2016. The changes in PAH contents and soil index in the soil were measured from July to September 2016. It showed that more naphthalene, anthracene, phenanthrene, fluorene, and flexion were detected in the three oil treatments. From July to September, three high-concentration oil treatments had inhibited soil urease activity in soil significantly except the diesel oil treatment with high concentration in August. The diesel and lubricating oil treatments had inhibited phosphatase and invertase activities in soil significantly. Three oil treatments inhibited the number of bacteria significantly in July. The total number of bacteria and fungi was highest in gasoline, and the total number of actinomycetes was highest in lubricating oil. The three oils affected the soil enzyme activity and the number of soil microorganisms and caused some damage to the soil ecological environment.