The impact of carbon nanomaterials on the development of phenanthrene catabolism in soil

This study investigates the impact of different types of carbon nanomaterials (CNMs) namely C60, multi-walled carbon nanotubes (MWCNTs) and fullerene soot on the catabolism of (14)C-phenanthrene in soil by indigenous microorganisms. Different concentrations (0%, 0.01%, 0.1% and 1%) of the different CNMs were blended with soil spiked with 50 mg kg(-1) of (12)C-phenanthrene, and aged for 1, 25, 50 and 100 days. An increase in the concentration of MWCNT- and FS-amended soils showed a significant difference (P = 0.014) in the lag phase, maximum rates and overall extent of (14)C-phenanthrene mineralisation. Microbial cell numbers did not show an obvious trend, but it was observed that control soils had the highest population of heterotrophic and phenanthrene degrading bacteria at all time points

Impact of activated carbon on the catabolism of (14)C-phenanthrene in soil

Activated carbon amendment to contaminated soil has been proposed as an alternative remediation strategy to the management of persistent organic pollutant in soils and sediments. The impact of varying concentrations (0%, 0.01%, 0.1% and 1.0%) of different types of AC on the development of phenanthrene catabolism in soil was investigated. Mineralisation of (14)C-phenanthrene was measured using respirometric assays. The increase in concentration of CB4, AQ5000 or CP1 in soil led to an increase in the length of the lag phases. Statistical analyses showed that the addition of increasing concentrations of AC to the soil significantly reduced (P < 0.05) the extent of (14)C-phenanthrene mineralisation. For example, for CB4-, AQ5000- and CP1-amended soils, the overall extent of (14)C-phenanthrene mineralisation reduced from 43.1% to 3.28%, 36.9% to 0.81% and 39.6% to 0.96%, respectively, after 120 days incubation. This study shows that the properties of AC, such as surface area, pore volume and particle size, are important factors in controlling the kinetics of (14)C-phenanthrene mineralisation in soil

Assessment of PAH contaminated land:implementing a risk-based approach

Abstract Polycyclic aromatic hydrocarbons (PAHs) are amongst the most common ubiquitous anthropogenic pollutants of terrestrial ecosystems. There are currently multiple sources of PAHs in Nigeria and land use activities have been shown to alter the composition of PAHs and in some cases increase the fractions of carcinogenic and recalcitrant components. This report considers the implementation of a more specific risk based corrective action to abate threats caused by carcinogenic PAHs in eroded and degraded soils for prospective risk assessment and realistic decision-making. Bioremediation is promoted for degradation of PAHs in soils, but faces several limitations that question the effectiveness of the approach. This review provides insights into bioaccessibility and chemical activity assessment of PAHs as a procedure of risk assessment and the potential use of specially produced biochar designed for specific risk mitigation remedial action was also considered

Impact of carbon nanomaterials on microbial activity in soil

In this study, effects of an increase in concentration of ftillerene-C-60, single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs) or fullerene soot (FS) on overall microbial activity was investigated over a 21 d incubation period. Microbial utilisation of C-14-glucose and uptake of C-14-glucose into the microbial biomass was investigated. For CNM-amended soils, greater extents of C-14-glucose mineralisation were found in the C-60-amended soils compared to MWCNT-, SWCNT- or FS-amended soils. In addition, the 100 and 1000 mg kg(-1) were consistently found to have higher extents of mineralisation in C-60, MWCNT, SWCNT or FS-amended soils, respectively. Further, the incorporation of C-14-glucose into the microbial biomass declined slightly with an increase in concentration in the amended soils, but no consistent pattern was observed. As a result, the biophysical quotient (BQ) increased significantly (

Effects of plant species identity, diversity and soil fertility on biodegradation of phenanthrene in soil

The work presented in this paper investigated the effects of plant species composition, species diversity and soil fertility on biodegradation of C-14-phenanthrene in soil. The two soils used were of contrasting fertility, taken from long term unfertilised and fertilised grassland, showing differences in total nitrogen content (%N). Plant communities consisted of six different plant species: two grasses, two forbs, and two legume species, and ranged in species richness from 1 to 6. The degradation of C-14-phenanthrene was evaluated by measuring indigenous catabolic activity following the addition of the contaminant to soil using respirometry. Soil fertility was a driving factor in all aspects of C-14-phenanthrene degradation; lag phase, maximum rates and total extents of C-14-phenanthrene mineralisation were higher in improved soils compared to unimproved soils. Plant identity had a significant effect on the lag phase and extents of mineralisation. Soil fertility was the major influence also on abundance of microbial communities. (C) 2012 Elsevier Ltd. All rights reserved