Abstract
Acid mine drainage is an important environmental risk linked to the surface storage of reactive mine tailings. To manage this problem, a cover with a capillary barrier effect (CCBE) can be used. This oxygen barrier cover relies on maintaining a fine-grained material layer (moisture-retaining layer, MRL) with a high degree of saturation. CCBEs can be colonized by surrounding plants. Plant roots pump water and could impact CCBE’s performance. This performance is predicted with unsaturated water flow numerical models in which vegetation parameters can be included. Vegetation parameters may be specific in a CCBE environment. Therefore, analyzing and quantifying the vegetation that colonizes this type of cover is necessary. Plant colonization was investigated through cover and density surveys on 12 transects on a 17-year-old CCBE in the mixed forest of Quebec, Canada. Then, aboveground vegetation and root colonization intensity at three depths in the MRL were characterized on 25 plots of five dominant vegetation types (Salix, Populus, Alnus, Picea sp., and herbaceous species). The mean root length density under plots dominated by Salix sp. was higher than in the other plots. Root colonization of the MRL was concentrated in the first 10 cm and occurred under all woody and herbaceous species as well. This work quantitatively describes, for the first time, the vegetation colonizing a CCBE both at the above- and belowground levels. These data will be useful to better predict the long-term performance of this engineered reclamation cover.
Highlights
Several reclamation methods have been developed to control the production of acid mine drainage (AMD), one of the main environmental problems associated with the storage of mine wastes
This paper considers three hypotheses: (1) herbaceous roots will not reach the moisture-retaining layer (MRL); (2) woody species roots will reach the MRL at 30 cm depth from the soil surface but should not go through it; (3) correlation between aboveground and belowground vegetation parameters should limit the need for direct sampling to quantify root colonization intensity in the MRL
Fifteen different woody species were present on site (Salix sp., Abies balsamea L. (Mill.), Larix laricina (Du Roi) K
Summary
Several reclamation methods have been developed to control the production of acid mine drainage (AMD), one of the main environmental problems associated with the storage of mine wastes In humid climates such as northern Quebec, one method is the use of an engineered cover, like a cover with a capillary barrier effect (CCBE) [1,2,3,4,5,6,7,8,9,10,11,12,13]. The PL, made of coarse-grained material, reduces evaporation and limits vegetation influence on the MRL The latter, made from fine-grained material, is the layer on which the CCBE’s performance is based and keeps oxygen away from the tailings by Minerals 2020, 10, 704; doi:10.3390/min10080704 www.mdpi.com/journal/minerals
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