Effect of humic deposit (leonardite) on degradation of semi-volatile and heavy hydrocarbons and soil quality in crude-oil-contaminated soil

Abstract

In order to investigate the bioremedial potential of humic deposit (leonardite), the effects of the treatments of leonardite and a commercial bioaugmentation agent on the degradation of a variety of petroleum hydrocarbons (C13-C31) and soil enzyme activities (urease acid-alkaline phosphatase and dehydrogenase) were tested within a soil incubation experiment lasting 120 days. Experimentally crude-oil-contaminated soil (2.5%) was regulated to a C:N:P ratio (100:15:1; Oilcon), amended with 5% of leonardite and regulated to the same C:N:P ratio (Oilcon-L) or mixed with a commercial bioaugmentation product (Oilcon-B), respectively. In the short period of incubation (60 days), Oilcon and Oilcon-B treatments showed higher hydrocarbon degradations, whereas Oilcon-L showed higher hydrocarbon degradation over Oilcon and Oilcon-B treatments in the long-term (120 days). Applying contaminated soil with leonardite increased urease (LSD, 4.978, *P<0.05) and dehydrogenase (LSD, 0.660, *P<0.05) activities. However, acid and alkaline phosphatase activities showed no certain inclination between different treatments. Dehydrogenase seemed to be more related to hydrocarbon degradation process. Overall results showed that leonardite enhanced biodegradation of petroleum hydrocarbons and also stimulated soil ecological quality measured as soil enzyme activities.

Activity and functional diversity of microbial communities in long-term hydrocarbon and heavy metal contaminated soils

“…The activity of soil enzymes is often used to monitor the effects of various pollutants on microbial functioning (Turgay et al 2010, Tang et al 2014, Tomkiel et al 2015. In the tested soils, the activities of a range of enzymes contributing to the biogeochemical cycle of carbon, nitrogen and phosphorus were determined (Fig.…”

“…Several studies have demonstrated that DHA is among the most sensitive parameters for evaluation of hydrocarbons toxicity and stress (Irha et al 2003, Gianfreda et al 2005. Turgay et al (2010) observed that the decrease in the content of hydrocarbons resulted in an increase of DHA over time during the bioremediation process of soil contaminated with petroleum hydrocarbons. However, Tang et al (2012) examining the bioavailability of petroleum hydrocarbons under different attenuation conditions noticed an increase in DHA immediately after the contamination of soil and its decline with the duration of the experiment.…”

Effect of wasterwater sludge application on enzyme activities in soil contaminated with crude oil

“…Phosphatase activity (PA) is important to soil P cycling. PA is sensitive to environmental perturbations and might therefore be a suitable selection for inclusion in the soil quality index (Turgay et al, 2010). This study clearly demonstrated the application of wastewater sludge in biodegradation of TPH by native microbial consortium not only as biostimulant, but also as inducers of degrader enzymes released by the microorganisms.…”

“…Turgay et al, (2010) reported that some enzymes, including phosphatase, are involved in N and P cycling and might not directly influence hydrocarbon presence.…”

Enzymatic remediation of the polluted crude oil by Rhodococcus

“…Thus, it would come to a burning question to treat the oil-polluted soil to recovery level in a short period (Turgay et al, 2010). The bioremediation technology could be adopted because of its low cost, pollution-free, and high efficient characters.…”