Sensitivity of the Endogeic Tropical Earthworm Pontoscolex corethrurus to the Presence of Heavy Crude Oil

Abstract

Contamination of soil with petroleum is common in oil-producing areas across the tropical regions of the world. There is limited knowledge on the sensitivity of endogeic tropical earthworms to the contamination of soil with total petroleum hydrocarbons (TPH) present in crude oil. Pontoscolex corethrurus is a dominant species in tropical agroecosystems around oil-processing facilities. The sensitivity of P. corethrurus to soil artificially contaminated with "Maya" Mexican heavy crude oil was investigated through avoidance and acute ecotoxicity tests, using the following measured concentrations: 0 (reference soil), 551, 969, 4845, 9991 and 14,869 mg/kg. The avoidance test showed that P. corethrurus displayed a significant avoidance behavior to heavy crude oil at a concentration of 9991 mg/kg or higher. In contrast, acute toxicity tests indicate that the median lethal concentration (LC) was 3067.32 mg/kg; however, growth (weight loss) was more sensitive than mortality. Our study revealed that P. corethrurus is sensitive to TPH, thus highlighting the importance of P. corethrurus for petroleum ecotoxicological tests.

Porcellio scaber Latr. and Lumbricus terrestris L.—PAHs Content and Remediation of Long-Term Aging Soil Contamination with Petroleum Products during a Single- and Two-Species Experiment

“…The same concentration (1%) of unweathered Arabian light crude oil caused 75% mortality of L. terrestris after 15 days of exposure, with E. fetida showing lower mortality compared to L. terrestris when the oil was weathered (30%), but higher mortality when the oil was unweathered (90%) [40]. On the other hand, in the case of the tropical earthworm Pontoscolex corethrurus (an endogenous species, like L. terrestris), Cuevas-Diaz et al [32] found the median lethal concentration (LC50) of TPH in soil contaminated with "Maya" Mexican heavy crude oil to be 3067.32 mg/kg (during a 14-day test). The LC/EC50 for L. terrestris in lubricating oil composed mainly of C 10 -C 16 and >C 16 -C 34 petroleum hydrocarbons was 2158 mg TPH/kg of dry soil (14 days test) [41].…”

“…In the available literature, body mass change was much less frequently analyzed than survival rate. Weight gain of earthworm P. corethrurus was a parameter more sensitive to the presence of contaminants than its mortality [32]. After 7 and 14 days of exposure to "Maya" Mexican heavy crude oil (4845 mg TPH/kg), this earthworm responded with decreases in biomass of 29.5% and 35.6%, respectively.…”

“…Research on the use of invertebrates in the remediation of petroleum contaminants has mostly focused on contaminants with crude oil [3,13,[30][31][32]. Only a few deal with petroleum products.…”

Risk Indicators for Agricultural Use in Oil-Contaminated Soils

“…There are many studies and ex-situ assays that indicate the risk factors of the total petroleum hydrocarbon content (TPH) by assessing plants, earthworms (Cuevas-Díaz et al 2017), microorganisms, ecosystems soil (Shen et al 2016) and food production (Yan et al 2015). There are not indicators to conduct a simple in-situ assessment of risk factors based on analyzing agroecosystems in oil-contaminated zones.…”