Tailings revegetation - on non-ameliorated substrate
Titel:
Tailings revegetation - on non-ameliorated substrate
Auteur:
Osborne, J.M.
Verschenen in:
International journal of mining, reclamation and environment
Paginering:
Jaargang 14 (2000) nr. 2 pagina's 161-169
Jaar:
2000
Inhoud:
The Westonia open pit gold mine, 320 km east of Perth, Western Australia (31°18'S, 118°42'E) was decommissioned in July 1991. Normandy Mining Pty Ltd seeded in May-June I993, the entire surface of the tailings storage facility. The rehabilitation objective was to stabilise the tailings structure. Tailings slurry had been pumped into three Cells at different periods throughout mining operations. The near surface layer of tailings is most significant from a rehabilitation perspective, as it is where plants are growing. Vegetated areas have lower salinity than areas lacking vegetation (8.23 compared with 47,39 dS m-1 ECe). Revegetation density averages 1.734 stems m-2 in October 1999 and foliage cover is 30%. Nine chenopods were recorded in October 1999 with Maireana brevifolia, Atriplex undulata and A. leniiformis more prevalent. Grasses continue to show accelerated establishment. A cryptogamic cover prevalent over the upper surfaces of 'raw' tailings appears to be enhanced under established vegetation where moisture levels and the soil nutrient status are inherently higher. The tailings profile in the centre of the third cell (vegetation absent) showed similar changes in salinity to previous samplings. The surface sample in April 1999 (102 dS m-1) was less saline than the April 1998 sampling (225 dS m-1). The layer between 0.1 m and 0.4 m remains extremely saline, i.e. range 83-150 dS m-1 ECe. Around the perimeter of his cell the tailings is coarser, and sampling of the profile to 0.3 m depth gave salinities from 5 to 20 dS m-1 ECe.
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