A greenhouse study was conducted to investigate the growth of the grass cover crops Agrostis capillaris, Festuca ovina, F. rubra, Lolium perenne, and Phleum pratense and their accumulation of Cu, Pb, Zn, Ni, and Cr in three metal‐contaminated wastes arising from a steelworks, a lead mine, and a chemical works. Soil metals were extracted by five reagents (Mehlich 1, 0.1 M HCl, 0.005 M DTPA, 0.005 M EDTA, 0.005 M NTA) and values were correlated with plant tissue accumulation of metals. Agrostis capillaris accumulated the greatest concentration of metals from each waste material. Dry matter production for all grasses decreased on contaminated substrates compared to the control; however, overall ground cover was satisfactory except for A. capillaris on the chemical works waste. Lolium perenne and P. pratense consistently produced the highest dry matter yields. All grasses accumulated excessive amounts of Cr on the chemical waste and Pb on the mine waste, presumably from reservoirs in the readily extractable and soluble forms. The extractability of most metals was generally 0.1 M HCl > Mehlich 1 > DTPA = EDTA = NTA. Mehlich 1 did not appreciably extract Pb from two wastes. No extractant was able to represent metal uptake by a particular grass in a linear fashion.
Ironstone mine spoil leaves a legacy of land contamination and diffuse water pollution with acidic, metal-rich drainage. Reclamation for woodland may exacerbate water pollution due to spoil amendment and disturbance. Constructed wetland systems (CWS) are increasingly used for treating acid mine drainage but their performance is poorly understood. A combined approach was used to reclaim the Benhar ironstone spoil heap in Central Scotland. Trees have been planted in spoil treated with dried pelleted sewage sludge, limestone and peat. Spoil drainage (pH 2.7, 247 mg l−1 total Fe) passes through a CWS. Spoil throughflow, surface water chemistry and CWS performance were monitored for 12 months after reclamation. Acidity, Fe, Mn and Al concentrations declined in throughflow after reclamation, although this effect was not uniform. Soluble reactive P has been mobilised from the sewage sludge in residual areas of spoil acidity, but losses of other nutrients were short-lived. The CWS removes on average 33 % and 20–40% of acidity and metal inputs but removal rates decrease in winter. Spoil reclamation has been successful in enabling vegetation establishment but has also increased Fe and Mn concentration in surface drainage from the site, even after passage through the CWS.
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