Phytotoxicity of oil sands naphthenic acids and dissipation from systems planted with emergent aquatic macrophytes

Abstract

Differences in dissipation and phytotoxicity were measured for two naphthenic acid mixtures in hydroponically grown emergent macrophytes (Typha latifolia, Phragmites australis, and Scirpus acutus). One of the naphthenic acid (NA) mixtures was extracted from tailings pond water of an oil sands operation in Fort McMurray, Alberta, Canada. The other mixture was a commercially available NA mixture. While the oil sands NA mixture was less phytotoxic to wetland plants compared to the commercially available NA mixture, they were not sequestered by wetland plants like their commercial NA counterparts. The small loss of commercial NAs from the spiked hydroponic system appeared to be selective and dependant on the specific NA compound. The results of this study indicate that plants alone may not mitigate NAs from oil sands tailings pond water. In addition, caution should be taken when making predictions on the environmental fate of oil sands naphthenic acids when using commercial NAs as surrogates.

Shifts in Root-Associated Microbial Communities ofTypha LatifoliaGrowing in Naphthenic Acids and Relationship to Plant Health

“…Although less information is available on the feasibility of using macrophtyes to remediate NA contaminated water, work by Crowe et al, (2001Crowe et al, ( , 2002 suggests that macrophytes such as Typha latifolia (cattail) are able to adapt to TPW contaminated conditions with little or no toxic effects. These results were corroborated during a recent study by our group, which also found that NAs from TPW exerted no significant toxic effects on cattails (Armstrong et al, 2008). In contrast, commercial NAs (Fluka…”

“…A common plant used in these wetlands, either by design or because they tend to self-volunteer, is the emergent macrophyte Typha latifolia (cattail). However, a recently published study by our group (Armstrong et al, 2008) found that while oil sands naphthenic acid (NA) mixtures were less phytotoxic to cattails than commercial NA mixtures, little uptake or degradation of NA occurred. It may be that in order for wetland phytoremediation systems to be optimized as an effective treatment option for TPW, both plant and bacterial communities must be specifically stimulated.…”

“…Before this stage is reached however, more information is required on the effects that NAs have on the plant-bacterial relationships. In this study, we expanded on the work of Armstrong et al, (2008) by examining the composition of bacterial communities associated with cattails in the presence and absence of NAs, and investigated whether specific changes in microbial community composition might impact plant health as measured by plant growth.…”

“…Cattails were sampled from a study on the efficacy of using different macrophytes to enhance the degradation of NA (previously published: Armstrong et al, 2008). To briefly summarize, cattail root cuttings from a native wetland plant nursery (Bearberry Creek Water Gardens, Sundre, AB, Canada) were acclimatized to growth chamber conditions in modified Hoagland's nutrient medium for at least three weeks and then single plants were transferred to individual hydroponic systems containing sterile Hoagland's nutrient medium.…”

“…Cattails were then grown in the hydroponic systems for two weeks prior to NA addition. Oil sands NA were extracted from tailings pond water (Fort McMurray, AB, Canada) using an adapted liquid-liquid extraction method (see Armstrong et al, 2008) and Fluka commercial NA mixture was obtained from Sigma-Aldrich Canada Ltd (Oakville, ON, Canada).…”