Impact of biodegradable lubricant oils on soil element concentrations

Abstract

This study deals with the biodegradation of vegetable oils commonly used in the forestry industry. Sampling was performed in the National nature reserve Slnečné skaly in Rajecká basin, Slovakia. Eighty soil samples contaminated with biodegradable lubricant oil and eighty control samples were collected. The samples were collected from ten pairs of plots (oil and control) once a week for eight calendar weeks following chain saw use. Biodegradable vegetable oil had significant effects on the concentration of several elements. Amounts of K, Ti, Mn, Cr, Fe, Rb, Sr, Zr and Ba significantly decreased in some of the oil plots when compared to control plots. However, this effect was found to be related to the unique environmental conditions of these plots. Element concentrations in soil samples were observed to be reduced approximately three weeks following the commencement of the experiment, corresponding to the estimated time of degradation of our used oil. The biodegradable oil had a negative effect on Ca binding in the soil and this study found that oil tends to have an effect on the binding of Ca in the soil after 5 weeks. The oil samples had higher levels of Pb and S than the control samples, whereas the contents of S and Pb were closely related. Sulphur likely decreased soil pH and increased availability and mobility of Pb. Additionally, the biodegradable lubricant oil had a slight non-significant negative impact on amounts of Cu found in the soil.