We studied the effectiveness of remediation on microbial endpoints, namely microbial biomass and activity, microbial and plant species richness, of an As-contaminated mine spoil, amended with compost (C) alone and in combination with beringite (B) or zerovalent iron grit (Z), to increase organic matter content and reduce trace elements mobility, and to allow Holcus lanatus and Pinus pinaster growth. Untreated spoil showed the lowest microbial biomass and activity and hydrolase activities, and H. lanatus as sole plant species, whereas the presented aided phytostabilisation option, especially CBZ treatment, significantly increased microbial biomass and activity and allowed colonisation by several plant species, comparable to those of an uncontaminated sandy soil. Microbial species richness was only increased in spoils amended with C alone. No clear correlation occurred between trace element mobility and microbial parameters and plant species richness. Our results indicate that the choice of indicators of soil remediation practices is a bottleneck. Organo-mineral amendment and revegetation of a gold mine spoil increased microbial activity but did not increase microbial species richness.

Temporal changes in microbial community function (enzymatic activities) and structure (phospholipid fatty acids) were studied in a post-mining chronosequence of coal discard sites of different rehabilitation ages. The objective was to determine whether temporal changes in microbial community function and structure were related to rehabilitation age or management practices. No trends consistent with the rehabilitation ages (1 to 11 years) of the respective sites were observed. A canonical correspondence analysis showed that sites clustered according to the time of sampling irrespective of their individual rehabilitation ages. Sites sampled in 2002 clustered together, while sites sampled in 2004 and 2005 clustered separately from the 2002 sites. This corresponded with a change in management practices applied after 2002. Dehydrogenase, β-glucosidase, acid phosphatase, and alkaline phosphatase activities for all sites were higher after 2002. Urease activities were lower after 2002, with the exception of Site 3 (4 years old in 2002). Phospholipid fatty acid data showed significant (p < 0.05) differences between sites of different rehabilitation ages over the study period. There was a decrease in microbial biomass in all sites from 2002 to 2004 but an increase in 2005. Fungal to bacterial abundance ratios for all sites decreased over the study period. The proportion of the total microbial community comprised of Gram positive bacteria increased from 2002 to 2005. These data show the value of microbial community function and structure to elucidate management effects that may not be apparent through traditional assessments of rehabilitation status such as aboveground indicators.

Two kinds of common turfgrass, fescue and ryegrass, were grown in soils amended with 20 x 80% sludge compost (SC) in this research. The effects of SC on two kinds of soil and response of fescue and ryegrass to the SC amendment were studied. The results showed that urease activity, extractable content of Cu and Zn and Electrical conductivity of both soils increased while pH decreased with the increase of SC amendment. However, the change of these parameters also depended strongly on soil characteristics. Sludge compost at the <=40 and <=60% levels can improve growth of fescue and ryegrass, respectively. The biomass of fescue grown in substrate with 40% SC increased 27% in a red soil and 44% in a yellow loamy soil compared to the control. The biomass of ryegrass grown in substrate with 60% SC increased 120% in the red soil and 86% in the yellow loamy soil. Sludge compost amendment at these levels did not significantly affect soluble salt contents of soil or Cu and Zn in plant tissue. Therefore, rational use of sludge compost can take advantage of its beneficial effect as a nutrient source for plant production while avoiding the potential deleterious effects on soil and plant.

Fluoride, a common phytotoxic air, water and soil pollutant is commonly released to the environment by a number of industrial processes. Agricultural soils high in fluoride are common due to long term accumulation of fluoride from multi-sources and extensive application of phosphate fertilizers. The effect of sodium fluoride (0, 50,100,150 mM) on growth, pigments content, changes in biochemical parameters, along with fluoride and other ions accumulation was investigated in Salicornia brachiata grown in solution cultures under controlled conditions. With fluoride treatment growth as fresh or dry mass accumulation increased marginally. However, higher concentrations decreased the biomass and shoot tip became blunt; margin of the shoot changed its colour to reddish brown and developed necrotic spots. Photosynthetic pigments (chlorophylls and carotenoids) content decreased, while, anthocyanin content increased significantly with fluoride treatment. Peroxidase (POX), superoxide dismutase (SOD), ATPase and acid phosphate activities were negatively regulated. In addition F-, Na⁺, Mn²⁺ and Fe²⁺ ions concentration increased while, K⁺, Ca²⁺ and Mg²⁺ contents decreased with fluoride treatment. To our knowledge this is the first report on fluoride tolerance in a marshy halophytes using as high as 150 mM concentration and the results suggest that S. brachiata is a moderately fluoride tolerant annual halophyte and may be useful to vegetate the fluoride contaminated marshy lands.