Framework for assessment and phytoremediation of asbestos-contaminated sites

Our plain-English summary of Framework for assessment and phytoremediation of asbestos-contaminated sites, by C. Gonneau, K. Miller, S.K. Mohanty, et al (Environmental Science and Pollution Research International, 2017).

The study

• Authors: C. Gonneau, K. Miller, S.K. Mohanty, R. Xu, W.T. Hwang, J.K. Willenbring, B.B. Casper
• Journal: Environmental Science and Pollution Research International
• Published: 2017;24(33):25912-25922
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

We examine the feasibility of phytoremediation as an alternative strategy to limit the exposure of asbestos in site with asbestos-containing materials. We collected soils from four locations from two sites-one with naturally occurring asbestos, and another, a superfund site, where asbestos-containing materials were disposed over decades-and performed ecotoxicology tests. We also performed two experiments with crop cultivar and two grasses from serpentine ecotype and cultivar to determined best choice for phytoremediation. Asbestos concentrations in different size fractions of soils varied by orders of magnitude. However, different asbestos concentrations had little effect on germination and root growth. Presence of co-contaminants such as heavy metals and lack of nutrients affected plant growth to different extents, indicating that several of these limiting factors should be considered instead of the primary contaminant of concern. Crop cultivar survived on asbestos-contaminated soil. Grasses from serpentine ecotype did not show higher biomass than the cultivar. Overall, these results showed that soil conditions play a critical role in screening different crop species for phytoremediation and that asbestos concentration has limited to no effect on plant growth. Our study provided a framework for phytoremediation of asbestos-contaminated sites to limit long-term asbestos exposure.

In plain English

This was a study of soil and plants, not of people. In spring 2015 the authors collected soil from two Pennsylvania sites. One was the BoRit Superfund site in Ambler, where asbestos-containing material had been discarded and the soil contained chrysotile. The other was the Nottingham serpentine site, where asbestos occurs naturally and the grassland soil contained anthophyllite. The standard CARB 435 method measured asbestos below 1% at both BoRit locations. The ASTM D7521-13 method, which tests soil size fractions separately, found 10 to 12% in the coarse fraction and 6 to 8% in the medium fraction at BoRit. In an ecotoxicology test on soils from all four locations, the pattern of seed germination was not related to asbestos concentration. Germination of eight species on BoRit soil did not differ from a control soil (p = 0.66). All eight crop species grew more in BoRit soil than in a compost and sand control. Soil microbes from the serpentine site did not change grass biomass. The authors concluded that asbestos itself did not affect plant health, although poor nutrients or other plant-toxic contaminants could.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Field soil sampling with comparison of two asbestos measurement methods, plus laboratory and greenhouse plant experiments (an ecotoxicology test, a germination test, and two plant growth experiments)
• Who was studied: Soils from four locations at two Pennsylvania sites, collected in spring 2015. At the BoRit Superfund site (Ambler, PA) the locations were a former reservoir and a stream bank. At the Nottingham Park serpentine site (Chester County, PA) they were a grassland and a former chromite mine waste pile. Several plant species and cultivars were grown on these soils.
• Exposure: Asbestos in soil: chrysotile at both BoRit locations, where asbestos-containing material had been discarded from a nearby manufacturing plant over several decades, and anthophyllite (amphibole) in the naturally occurring asbestos grassland soil at Nottingham
• Main results:
  • With the CARB 435 method, asbestos was below 1% in both BoRit locations and in the Nottingham grassland. The BoRit stream bank had 0.75% and the BoRit reservoir 0.5%.
  • With the ASTM D7521-13 method, the coarse and medium soil fractions at BoRit contained 10 to 12% and 6 to 8% asbestos respectively, compared with less than 1% in the fine fraction
  • The authors reported that the ASTM method gave better insight than CARB 435 into asbestos concentration and its distribution across soil particle sizes
  • All soil fractions from the Nottingham grassland had similar asbestos concentrations (2.0%). At the Nottingham chromite mine waste pile, asbestos was below the detection limit (0.25%).
  • In the ecotoxicology test on all four soils, germination of the two Brassicaceae species was inhibited by 0 to 15% compared with control soil. Germination of Sorghum saccharatum was inhibited by 15 to 35%.
  • In the ecotoxicology test, the germination pattern was not related to asbestos concentration, which the authors said suggests asbestos does not directly threaten plants
  • Soil from the Nottingham chromite mine inhibited root growth of Lepidium sativum and Sinapis alba more than any other soil
  • For eight species tested together, germination did not differ between the two BoRit soils and the control soil (p = 0.66)
  • Seeds in the Brassicaceae family had significantly higher odds of germination than seeds in the Poaceae family (p less than 0.01)
  • For the Poaceae species, germination was below 50% after 9 days
  • In the crop cultivar experiment, biomass of all species was higher in BoRit soil than in the compost and sand control
  • Only three species (Brassica oleracea, Andropogon gerardii and Sorghum bicolor) showed significantly different biomass among the three soils
  • Iron concentrations in the plants were below 100 mg per kg for all species in all three soils, a level considered deficient
  • In the C4 grass experiment on BoRit soils, live soil microbial inoculum from Nottingham had no effect on biomass for either grass species
  • Biomass was greatest for Holt, a commercial cultivar of Sorghastrum nutans, compared with the other three species and seed source combinations
• The authors' conclusion: The authors concluded that asbestos itself did not affect plant health, although insufficient nutrients or high levels of other plant-toxic contaminants could

Topics

Medical terms in this study, explained in our Lexicon: Asbestos-Containing Material (ACM), naturally occurring asbestos (NOA), Superfund, Serpentine Group, Asbestos Exposure.

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