The Key Factors for the Fate and Transport of Petroleum Hydrocarbons in Soil With Related in/ex Situ Measurement Methods: An Overview

Abstract

Once petroleum hydrocarbons (PHs) are released into the soil, the interaction between PHs and soil media is dependent not only upon the soil properties but also on the characteristics of PHs. In this study, the key factors influencing the interactions between PHs and soil media are discussed. The key factors include: 1) the characteristics of PHs, such as volatility and viscosity; and 2) soil properties, such as porosity, hydraulic properties and water status, and organic matter; and 3) atmospheric circumstances, such as humidity and temperature. These key factors can be measured either ex-situ using conventional laboratory methods, or in situ using portable or handheld instruments. This study overviews the current ex/in situ techniques for measuring the listed key factors for PH contaminated site assessments. It is a tendency to apply in situ methods for PH contaminated site characterisation. Furthermore, handheld/portable Fourier transform infrared spectroscopy (FTIR) instrument provides tremendous opportunities for in-field PH contaminated site assessment. This study also reviewed the non-destructive FTIR spectroscopy analysis coupling with handheld FTIR for in-field PH contaminated site characterisation, including determining the concentration of total PH, dominant PH fractions and soil key properties for PH transport modelling.

Review and Perspective: Gas Separation and Discrimination Technologies for Current Gas Sensors in Environmental Applications

“…Equivalent carbon numbers (Cn), or the length of the carbon chain, are used to describe the aliphatic fractions. 121 The highly volatile hydrocarbon fractions (C6− C14) evaporate into the gas phase of the porous medium and may be lost to the atmosphere, adsorbed onto soil solids, or dissolved into soil water or groundwater. Based on the theory that xenon lamps can detect VOCs with more than six carbons (C6), the total recoverable hydrocarbons and C7−C16 fraction can be determined.…”

“…It is a common practice to use carbon fractions to classify PHs in high mixtures. Equivalent carbon numbers (Cn), or the length of the carbon chain, are used to describe the aliphatic fractions . The highly volatile hydrocarbon fractions (C6–C14) evaporate into the gas phase of the porous medium and may be lost to the atmosphere, adsorbed onto soil solids, or dissolved into soil water or groundwater.…”

Bioremediation of petroleum hydrocarbon contaminated soil: a review on principles, degradation mechanisms, and advancements

“…The first steps in the catabolism of aliphatic (Peng et al, 2008), cyclic (Perry and Gibson, 1977), and aromatic (Elufisan et al, 2020) hydrocarbons by bacteria and fungi require molecular oxygen to be oxidized by oxygenase enzymes. However, the availability of oxygen in soil is dependent on a number of factors, such as the microbial oxygen consumption rate, type of soil, whether the soil is waterlogged, and the presence of utilizable substrates that can lead to oxygen depletion (Wang et al, 2021). The concentration of oxygen has been identified as a rate-limiting factor (Kumar et al, 2019).…”

“…Soil acidity and alkalinity are significant factors in petroleum hydrocarbon biodegradation. Unlike most aquatic ecosystems, soil pH can be extremely variable, ranging from 2.5 in mine spoils to 11.0 in alkaline deserts (Wang et al, 2021). Soil pH inhibits microorganisms and enzyme activity, whereas most microbes prefer neutral pH for growth and HC remediation (Kumar et al, 2019).…”

Bioremediation of Soil from Petroleum Contamination

“…This leads to a considerable loss of water conductivity and capacity. As a result of greatly increased hydrophobicity, the upper contaminated layers dry out, whereas the cleaner lower layers suffer from excessive moisture, leading to incorrect air and water conditions and the development of anaerobic processes [28,29]. The abnormal water conditions lower solubility and availability of micronutrients to plants, hence inhibiting nitrification and ammonification.…”