Phytoremediation: Metal decontamination of soils after the sequential forestation of former opencast coal land

Abstract

Forest phytoremediation through forestry may be an effective means for reducing the metal loading in lands reclaimed after surface-coal-mining in the UK. Planted with mixed woodland, soil loadings of 5 key metals (Zn, Cd, Mn, Pb and Cu) decreased, significantly and progressively, compared to soils left as grassland, through a 14 year forestation chronosequence on land reclaimed from the former Varteg opencast coalmine, South Wales, UK. Fourteen years after initial tree planting, soil metal loadings decreased by 52% for Cd (4.3 mg.kg-1 per year), 48% for Cu (2.1 mg.kg-1 per year), 47% for Zn (7.3 mg.kg-1 per year), 44% for Pb. (7.1 mg.kg-1 per year) and 35% for Mn (45 mg.kg-1 per year). Analysis of metal loadings in the leaves of Alnus glutinosa (L. Gaertn) (Common Alder) and Betula pendula (Roth) (Silver Birch) found both species involved in metal uptake with birch taking up more Cd, Cu, Zn and Mn and Alder taking up more Pb. Concentrations of Zn, Mn and Cd (Birch only) increased significantly in leaves from, but not soils under, older plantings. Since different tree species take up metals at different rates, mixed plantings may be more effective in forest phytoremediation.

Composted Municipal Green Waste Enhances Tree Success in Opencast Coal Land Reclamation in Wales

“…As for metal contamination, previously, Desai et al 28 discovered no significant differences between the levels of Cd, Cu, Mn, Pb, and Zn in the soils and leaves of treated and untreated trees on this MD07 test plot. At the Ffos-y-fran opencast reclamation site, researchers also discovered no changes in metals consequential upon the addition of their PAS100 biofertiliser.…”

“…Even so, the amount of metals added is small compared with ambient local soil loadings. 28 In sum, on present evidence, there seem to be good positive reasons for, and no demonstrated negatives against, using this type of MGW in forestry contexts.…”

“…The problem is that this metal loading is an addition to pre-existing soil loadings. Fortunately, research on other Varteg test plots has shown that long-term forestation is an effective means of reducing the loadings of some heavy metal in these opencast coal mine substrates, 28 which means that the use of MGW is appropriate in the context of forestation.…”

Justification of phytoremediation technology of degraded landscapes on the basis of ecosystem approach

“…The land restoration technologies existing today do not sufficiently take into account the environmental component in the practice of general restoration of degraded landscapes [1]. So, in [2] it is shown that forestry phytoremediation can be an effective tool to reduce the content of Zn, Cd, Mn, Pb and Cu metals on mining lands in the UK. It is found that fourteen years after the first tree planting, the metal concentration in the soils decreased: Cd -by 52 %, Cu -by 48 %, Zn -by 47 %, Pb -by 44 %, Mn -by 35 %.…”

Effect of Reclamation on an Environment Impaired by Mining Activity: A Case Study

“…Technical papers which also deal with environmental impacts after mining activities are "Phytoremediation: Metal decontamination of soils after the sequential forestation of former opencast coal land" [9], "Hyperspectral inversion of heavy metal content in reclaimed soil from a mining wasteland based on different spectral transformation and modelling methods" [10] and "Evaluating sediment production from native and fluvial geomorphic-reclamation watersheds at La Plata Mine" [11].…”