Fertility Deterioration in a Remediated Petroleum-Contaminated Soil

Abstract

A soil that had been remediated by soil washing and chemical oxidation was evaluated, comparing it to an uncontaminated control soil ~30 m away. Profile descriptions were made of both soils over a 0–1 m depth, and samples were analyzed from each soil horizon. Samples were also analyzed from surface soil (0–30 cm). The control soil (a Fluvisol), had several unaltered A and C horizons, but the remediated soil presented only two poorly differentiated horizons, without structure and much lower in organic matter (<0.5%). In surface samples (0–30 cm), the bulk density, sand-silt-clay contents, field capacity, organic matter, and porosity were different with respect to the control (p > 0.05), and there was much greater compaction (3.04 vs. 1.10 MPa). However, the hydrocarbon concentration in the remediated soil was low (969.12 mg kg−1, average), and was not correlated to soil fertility parameters, such as porosity, organic matter, pH, moisture, field capacity or texture (R2 < 0.69), indicating that the impacts (such as compaction, lower field capacity and moisture content) were not due to residual hydrocarbons. Likewise, acute toxicity (Microtox) was not found, nor water repellency (penetration time < 5 s). It was concluded that the fertility deterioration in this soil was caused principally from the mixture of upper (loam) and lower (silty clay to silty clay loam) horizons during remediation treatment. Another important factor was the reduction in organic material, probably caused by the chemical oxidation treatment.

Changes in restored soils subject to weathering and their implication in Mexican environmental regulations

“…Finally, for all samples (controls and problems), were determined the parameters specif ied in Table 2 (n=3); the methods used were as specif ied by the Mexican norm NOM-021- RECNAT-2000(SEMARNAT, 2002, Domínguez and Aguilera (1989) and Domínguez-Rodríguez et al (2020).…”

“…It must be noted that remediation technologies are different and depend on the type of impact and hence, it turns out that each particular site represents a specif ic problem to be analyzed (Morales- Bautista et al, 2017). On this issue, most of the researchers agree that considerations such as the Maximum Permissible Limit (MPL), are not ideal diagnostic parameters nor environmental assessments since in some restored areas (with concentrations of pollutants below the MPL), persist alterations such as low hydraulic conductivity, compaction and water repellency and the development of plants or yield of crops is affected (Trujillo-Kanga, 2015; Domínguez-Rodríguez et al, 2020).…”

Soil Odor as An Extra-Official Criterion for Qualifying Remediation Projects of Crude Oil-Contaminated Soil

“…For the present study, compaction was not evaluated, being more prevalent in petroleumcontaminated soils with predominantly kaolinte clays [6], or in soils in which surface and subsurface horizons have been mixed during the remediation process [5]. As this study only involves surface soil, with very little clay (Arenosol) or with predominantly smectite clays (Fluvisol, Gleysol), compaction was not considered a primary fertility parameter likely to be impacted by crude oil contamination.…”

“…This possibility of personal corruptiblity puts the true compliance of the MPLs in question. Furthermore, there is no guarantee that remediated soils that achieve the MPLs will indeed have their fertility restored [5,6]. Often, these soils may still suffer from water repellency and reduction in the field capacity.…”

Soil contamination by petroleum in Tabasco, Mexico, and its environmental repercussions

“…In Tabasco, there are studies on oil spills (Sánchez-Pérez 2003), plant toxicity (Rivera-Cruz and Trujillo- Narcia 2004), decontamination of soils polluted by crude oil using indigenous microorganisms (Rivera-Cruz et al 2004), bioremediation processes (Ferrera-Cerrato et al 2006), restoration technologies (Zavala-Cruz et al 2002) and soil fertility (Domínguez-Rodríguez et al 2020).…”