Abstract
Unfortunately, many property owners in southeastern Mexico do not trust environmental authorities, and the de facto method they use to evaluate the progress in environmental remediation projects is soil smell. This criterion was evaluated to determine if it was reliable to assess soil fertility and toxicity. Three soils (Fluvisol, Gleysol, and Arenosol), were contaminated with 2% medium or heavy crude oil (30.2, 17.1°API, respectively), and treated for 18 months to simulate bioremediation or natural attenuation. Every two months, field capacity, water repellency, hydrocarbon concentration, acute toxicity and soil odor were measured. Odor was measured in controlled conditions with a group of unexperienced panelists. During remediation, the Fluvisol and Gleysol were perceived to have an odor intensity between slight to low, and were considered acceptable. Meanwhile, in the Arenosol, the odor intensity was between low to medium and was considered unacceptable. After treatment, the hydrocarbon concentration was reduced to low levels, very near Mexican norm, and all the soils, including the Arenosol, were perceived to have an intensity between neutral to slightly agreeable, were considered acceptable, and no toxicity was observed in the earthworm bioassay (no false positives). However, in various soil samples from the Fluvisol and Arenosol, important risks were present with respect to field capacity and water repellency. Due to these observations, even though soil smell may be a trustworthy guide to soil toxicity, it does not ensure that the remediated soil’s fertility has been restored.
Highlights
In Mexico, the regulations for the characterization and remediation of hydrocarbon-contaminated sites are governed by a system of laws, regulations and norms, which together try to guarantee that site remediation achieves three objectives: 1) protection of the environment, including living beings and biological processes, 2) protection of public health, and 3) restoration of the site such that it can be used according to its natural vocation or any activity considered in a program of urban development
Among those actions which should be considered in the remediation of contaminated sites are the reduction in toxicity, the potential for leachates, as well as those measures that permit the re-establishment of the physical and chemical properties associated with soil fertility [2]
The detailed results of initial soil characterization and major changes in Total Petroleum Hydrocarbons (TPHs) resulting from the semi-passive bioremediation or natural attenuation are shown in the Supplementary Material accompanying this article (Table S1, Figures S5–S8)
Summary
In Mexico, the regulations for the characterization and remediation of hydrocarbon-contaminated sites are governed by a system of laws, regulations and norms, which together try to guarantee that site remediation achieves three objectives: 1) protection of the environment, including living beings and biological processes, 2) protection of public health, and 3) restoration of the site such that it can be used according to its natural vocation or any activity considered in a program of urban development Among those actions which should be considered in the remediation of contaminated sites are the reduction in toxicity, the potential for leachates (and contamination of water bodies and aquifers), as well as those measures that permit the re-establishment of the physical and chemical properties associated with soil fertility [2]. Res. Public Health 2020, 17, 3213; doi:10.3390/ijerph17093213 www.mdpi.com/journal/ijerph
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