The Impact of Diesel Oil Pollution on the Hydrophobicity and CO2 Efflux of Forest Soils

Abstract

The contamination of soil with petroleum products is a major environmental problem. Petroleum products are common soil contaminants as a result of human activities, and they are causing substantial changes in the biological (particularly microbiological) processes, chemical composition, structure and physical properties of soil. The main objective of this study was to assess the impact of soil moisture on CO2 efflux from diesel-contaminated albic podzol soils. Two contamination treatments (3000 and 9000 mg of diesel oil per kg of soil) were prepared for four horizons from two forest study sites with different initial levels of soil water repellency. CO2 emissions were measured using a portable infrared gas analyser (LCpro+, ADC BioScientific, UK) while the soil samples were drying under laboratory conditions (from saturation to air-dry). The assessment of soil water repellency was performed using the water drop penetration time test. An analysis of variance (ANVOA) was conducted for the CO2 efflux data. The obtained results show that CO2 efflux from diesel-contaminated soils is higher than efflux from uncontaminated soils. The initially water-repellent soils were found to have a bigger CO2 efflux. The non-linear relationship between soil moisture content and CO2 efflux only existed for the upper soil horizons, while for deeper soil horizons, the efflux is practically independent of soil moisture content. The contamination of soil by diesel leads to increased soil water repellency.

Influence of Abandoning Agricultural Land Use on Hydrophysical Properties of Sandy Soil

“…Despite simplifications in reflecting field conditions (e.g., the lack of vegetation), the obtained results indicate the direction of changes in the rainfall-runoff relationship when the phenomenon of water repellency occurs. Water repellency was characterized by seasonality, which was also observed by Buczko et al [17,18], Leighton-Boyce et al [26], and Hewelke et al [11,15]. On the analyzed site, the soil was wettable in the period of early spring, whereas the phenomenon of water repellency occurred after a longer period without rainfall.…”

“…The reasons behind water repellency are being identified to an increasingly wider extent and are related to the occurrence of organic carbon, especially humic and fulvic acids, as well as waxes and lipids of different origins [2][3][4][5][6]. Water repellency also occurs following forest fires and the burning of grasses [7][8][9][10][11] as well as soil contamination with crude oil derivatives [12][13][14][15]. Water repellency is of a seasonal nature and is strictly connected with soil moisture content [16][17][18][19][20][21].…”

Soil Functional Responses to Natural Ecosystem Restoration of a Pine Forest Peucedano-Pinetum after a Fire

“…Decreasing the infiltration of water has a detrimental impact on the retention, habitat and production functions of the soil. Typically, increased surface runoff and erosion [17,[32][33][34] make it impossible to fully take advantage of the retention abilities of the soil, thus increasing its susceptibility to droughts. An irregular wetting front and preferential flow in the soil profile [35][36][37], due to the faster infiltration of water through privileged flow paths, can lead to the contamination of groundwater.…”

Hydrophysical properties of sandy clay contaminated by petroleum hydrocarbon

“…Especially important is the assessment of the water repellency of soil depending on its contamination and moisture content. According to earlier studies (Hewelke et al 2018b) carried out on sandy soils contaminated with petroleum hydrocarbon, the fastest natural biodegradation of the contaminating substance was obtained at a moisture content close to field capacity. The tested sandy clay (sand 47%) was characterized by a rising potential WDPT value trend depending on the level of contamination.…”

“…Drought not only induces water repellency but it also intensifies it. Under conditions of soil drought, the natural reduction in hydrocarbons by native soil bacteria could be slowed and not very efficient (Hewelke et al 2018b).…”