Specific Interactions between Local Metallicolous Plants Improve the Phytostabilization of Mine Soils

Abstract

At present, no efficient technique is available for cleaning up soils which are highly polluted by heavy metals. Limiting the movement of pollutants out of the contaminated area by creating a dense and persistent plant cover appears to be the more reasonable approach. In this context, phytostabilization is a technique that uses metallicolous plants to revegetate highly polluted soils.This paper presents the results of an experiment performed in situ using metallicolous ecotypes of four plant species native to the Mediterranean French region, and grown in different combinations at a polluted site over two years. The soils were highly polluted with zinc, cadmium and lead. The aim was to find the best species mixture in terms of cover, biomass and duration. The four species used were the biennial legume Anthyllis vulneraria, two perennial grasses, Festuca arvernensis and Koeleria vallesiana, and the perennial forb Armeria arenaria. Mixtures which included A. vulneraria, and especially when in combination with F. arvernensis, showed the highest values of cover and biomass. After flowering, the biennial individuals of A. vulneraria disappeared but subsequent germination and survival of seedlings occurred abundantly under the two grasses. Mixtures with A. arenaria showed the lowest values of cover and biomass. Soil nitrogen increased in the plots with A. vulneraria as well as the concentration of essential nutrients (N P K) in the aerial parts of the two grasses. In contrast, the concentration of metals (Zn Pb Cd) decreased in the aboveground biomass of the latter in the same plots.These results show that reciprocal facilitation effects can act in heavy metal polluted environments, and that phytostabilization efforts in the Mediterranean region can be improved by using mixtures including local metallicolous legume and grass species.

Nurse effect and herbivory exclusion facilitate plant colonization in abandoned mine tailings storage facilities in north-central Chile

“…In addition to the human wealth and welfare associated with this activity, it has generated intense environmental degradation through the production of a broad range of hard-rock residues, such as tailing storage facilities, heap leach piles, and smelter dust and slags (Asami 1988, Dudka & Adriano 1997. Abandoned tailing storage facilities (TSFs), for instance, are a potential source of pollution given their high metal concentrations (Badilla-Ohlbaum et al 2001, Frérot et al 2006, Ginocchio et al 2006. Loose tailings particulate matter is easily mobilized by wind, rain, and landslides, altering stream and soil quality, thus posing risks for crops, animal husbandry, wildlife, and human health (Petrisor et al 2004, Mendez & Maier 2008.…”

Copper microlocalisation, ultrastructural alterations and antioxidant responses in the nodules of white lupin and soybean plants grown under conditions of copper excess

“…The inclusion of nitrogen-fixing plants in stabilizing vegetation might, therefore, help in ecosystem development by increasing the soil nitrogen content available, and through the promotion of plant cover (Frérot et al, 2006). Unfortunately, N 2 fixation is sensitive to heavy metal pollution.…”

Metal concentration and metal mass of metallicolous, non metallicolous and serpentine Noccaea caerulescens populations, cultivated in different growth media

“…In each population, seeds from 20-30 flowering plants were collected. To analyse the extractable Zn, Cd, Pb and Ni concentrations of soil, bulk samples were air-dried, ground and the <2 mm fractions were separated from coarse rock (Frérot et al 2006) Total Zn 126126±17620 mg/kg; total Cd 899±200 n=3 (Escarré et al 2011) b (Dechamps et al 2008a,b;Molitor et al 2005) c Total Zn concentration (Reeves et al 2001) d Total Ni concentration: 146 to 2500 mg/kg (Chardot et al 2007) e Total Ni concentration:784-1984 mg/kg (Reeves et al 2001) fragments by sieving. All chemical analyses were performed on the <2 mm soil fractions.…”