Root symbionts: a tool for remediation of gold mine tailings
Why this work is in the frame
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Bibliographic record
Abstract
The mining company IAMGOLD aims to reduce the environmental footprint of its Essakane project (Burkina Faso) through soil restoration projects. Mining activities generate important physical, chemical and biological impacts on the ecosystem. The main solid wastes produced (tailings and overburden), are often biologically dead substrates and contain excess contaminants such as cyanide (CN) and arsenic (As). The ecosystem restoration should be done with ecologically adapted native plant species. For this reason, studies of symbiotic interactions between these endemic taxa and associated symbionts are essential for enhanced reclamation and for promoting sustainable development of these disturbed soils. An evaluation of rhizobial and mycorrhizal inoculum potentials and of physico-chemical properties of materials with different degradation levels (tailings, waste rock, two sites reclaimed in 2009 and a natural site outside the mine) was carried out on Essakane’s mine. The results of this study showed an absence of ectomycorrhizal fungi and a very low presence of rhizobia and arbuscular mycorrhizal (AM) fungi on all materials. For AM fungi, the two disturbed sites showed lower spore density (less than 1 spore/100 g of soil) and root colonisation rate than the non-disturbed sites. This low presence of symbiotic microorganisms can be explained by high alkalinity (pH = 9) and low carbon content of these soils. Concomitantly, a greenhouse experiment was conducted to test different symbiotic inocula and substrates on Acacia senegal seedlings. The symbiotic inocula were the rhizobium strain ORS 3588 (from Senegal) and two strains of AM fungi (Glomus aggregatum, from Senegal; and a Canadian commercial product, Glomus irregulare) used alone or combined. The three substrates with different content of manure and sand (50:50; 25:75; 0:100) were tested to determine the ones that promote the best symbiotic colonisation. After 75 days, morphometric data on plants were analysed. The dry mass was significantly higher on substrates with manure. No effect of inoculation was observed except for the shoot dry mass, on the substrate without manure. In the 100% sand, shoot dry mass of plants inoculated with Glomus aggregatum was significantly higher from that of plants inoculated with Glomus irregulare, Rhizobium or without inoculum. All treatments with Glomus aggregatum are not significantly different. The non-Rhizobium inoculation effect yielded low rate of nodulation. Substrates and inocula had a significant impact on mycorrhizal colonisation. Nevertheless, we observed the presence of nodulation and mycorrhizal colonisation in control treatments. Further molecular analysis would be necessary in order to concisely identify the source of contamination of control plants. These results illustrate the need for isolating and selecting microbial inoculants adapted to soil nutrient limitation in order to develop efficient inoculum that would be used to enhance seedling growth on disturbed mining sites such as Essakane.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it