Metal toxicity and biodiversity in serpentine soils: application of bioassay tests and microarthropod index

Our plain-English summary of Metal toxicity and biodiversity in serpentine soils: application of bioassay tests and microarthropod index, by G. Visioli, C. Menta, C. Gardi, et al (Chemosphere, 2013).

The study

• Authors: G. Visioli, C. Menta, C. Gardi, F.D. Conti
• Journal: Chemosphere
• Published: 2013;90(3):1267-73
• Cited by: 20 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Eco-toxicological or bioassay tests have been intensively discussed as tools for the evaluation of soil quality. Tests using soil organisms, including microarthropods and plants, allow direct estimates to be made of important soil characteristics and functions. In this study we compared the results obtained by two in vitro standard bioassays following ISO or OECD guidelines: (i) the short term-chronic phytotoxicity germination and root elongation test using three different plant species Cucumis sativus L. (Cucurbitaceae), Lepidium sativum L. (Brassicaceae), and Medicago sativa L. (Fabaceae) and (ii) the inhibition of reproduction of Folsomia candida (Collembola) by soil pollutants to investigate the toxicity of a serpentine soil present in the Italian Apennines, rich in heavy metals such as Ni, Cr, and Co. In addition, microarthropod communities were characterised to evaluate the effects of metal contents on the soil fauna in natural conditions. Abundances, Acari/Collembola ratio, biodiversity indices and the QBS-ar index were calculated. Our results demonstrate that the two in vitro tests distinguish differences correlated with metal and organic matter contents in four sub-sites within the serpentinite. Soil fauna characterisation, not previously performed on serpentine soils, revealed differences in the most vulnerable and adapted groups of microarthropods to soil among the four sub-sites: the microarthropod community was found to be rich in term of biodiversity in the sub-site characterised by a lower metal content and a higher organic matter content and vegetation.

Copyright © 2012 Elsevier Ltd. All rights reserved.

In plain English

This laboratory and field study looked at the toxicity of serpentine (serpentinite) soil, which is naturally rich in metals such as nickel, iron and cobalt, at four sub-sites on Monte Prinzera in the northern Apennines, Italy. The article does not discuss asbestos. The authors measured soil metals, then ran germination and root growth tests with three plant species and a reproduction test with the springtail Folsomia candida. In spring and autumn 2011 they also counted the small soil animals (microarthropods) at each sub-site. Sub-site MP1s, a grassy wooded area, had lower total and available nickel and more organic matter than the other three. Its soil was less toxic to cress (germination index 53%, against 14% at MP4s), and springtail adult mortality ranged from 22.6% at MP1s to 44.3% at MP4s. MP1s had the most kinds of soil animals, but the biodiversity indices did not differ significantly between sites or seasons. The authors concluded that plant test results matched metal availability and that organic matter could reduce nickel toxicity. They said the data could not show how much the metals affected the soil animals.

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: Laboratory ecotoxicity tests (plant germination and root elongation; Folsomia candida survival and reproduction) combined with a field survey of soil microarthropod communities
• Who was studied: Soils from four sub-sites (MP1s to MP4s) on Monte Prinzera, northern Apennines, Italy, sampled in spring and autumn 2011. Test organisms were three plant species (Cucumis sativus, Lepidium sativum, Medicago sativa) and laboratory-raised springtails (Folsomia candida). Soil microarthropods were collected as three soil cores per site per season.
• Exposure: Naturally occurring metals (mainly nickel, iron and cobalt) in serpentinite soil. In the laboratory, nickel sulphate solutions and nickel nitrate added to artificial soil were also tested. No asbestos fibers were studied.
• Main results:
  • Sub-site MP1s had significantly lower total nickel than the other three sub-sites, and the highest organic matter and water content (p < 0.01). Soil pH did not differ.
  • The available (DTPA-extractable) fraction of nickel and iron was lower at MP1s than at the other three sub-sites.
  • In the Lepidium sativum (cress) soil tests, MP1s was the least toxic, with a germination index of 53%. MP4s had the strongest inhibitory effect, with a germination index of 14%.
  • In artificial soil with added nickel, Folsomia candida reproduction was inhibited by 96.5% to 100% (p < 0.05 for all concentrations).
  • In the natural soils, Folsomia candida adult mortality was 22.6% in MP1s, 32.8% in MP2s, 29.6% in MP3s and 44.3% in MP4s. Reproduction was suppressed significantly less than in the artificial soil with added nickel.
  • MP1s had 17 microarthropod groups in spring and 11 in autumn. MP2s had 7 in spring and 8 in autumn, MP3s had 10 and 7, and MP4s had 8 in both seasons.
  • The biodiversity and soil quality indices (Shannon, Pielou, number of taxa, QBS-ar, Acari/Collembola ratio) did not differ significantly between sites or seasons.
• The authors' conclusion: The authors concluded that the plant toxicity tests correlated well with metal availability in the soil at the four sub-sites. They also concluded that Folsomia candida is sensitive to nickel, but that organic matter in the soil could reduce the toxic effect.
• Limitations the authors state:
  • The authors stated that their data could not establish how much the metal content of the soils was affecting the soil microarthropod community.
  • The authors stated that several interacting factors, not only metals, shape the microarthropod community.

Topics

The National Library of Medicine indexes this study under subjects our site covers: Chrysotile.

Medical terms in this study, explained in our Lexicon: Serpentine Group, Serpentinite.

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