Biochar as a sorbent for contaminant management in soil and water: a review.

Scattered literature is harnessed to critically review the possible sources, chemistry, potential biohazards and best available remedial strategies for a number of heavy metals (lead, chromium, arsenic, zinc, cadmium, copper, mercury and nickel) commonly found in contaminated soils. The principles, advantages and disadvantages of immobilization, soil washing and phytoremediation techniques which are frequently listed among the best demonstrated available technologies for cleaning up heavy metal contaminated sites are presented. Remediation of heavy metal contaminated soils is necessary to reduce the associated risks, make the land resource available for agricultural production, enhance food security and scale down land tenure problems arising from changes in the land use pattern.

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Heavy Metals in Contaminated Soils: A Review of Sources, Chemistry, Risks and Best Available Strategies for Remediation

The science of the total environment

Organic and inorganic contaminants removal from water with biochar, a renewable, low cost and sustainable adsorbent--a critical review.

Application of biochar for the removal of pollutants from aqueous solutions.

This study investigated the impact of different root exudate components (RECs) on the availability of phenanthrene as a representative of polycyclic aromatic hydrocarbons (PAHs) in soil (TypicPaleudalfs) using laboratory batch assays Six typical RECs were compared including citric acid, oxalic acid, malic acid, alanine, serine, and fructose An n-butanol extraction procedure and a sorption experiment were used to predict the availability of phenanthrene in soil We found that both the n-butanol extraction and sorption process increased the availability of phenanthrene with increasing REC concentrations The availability of phenanthrene in soil with various treatments decreased in the following order: organic acids (citric acid > oxalic acid > malic acid) > amino acids (alanine > serine) > fructose treatments The mechanism of REC-influenced availability of PAH in soil is discussed based on the observed metal dissolution, soil organic matter reduction, and dissolved organic matter release from soil solids

The Impact of Different Root Exudate Components on Phenanthrene Availability in Soil

Carbon dioxide as a carrier gas and biomass addition decrease the total and bioavailable polycyclic aromatic hydrocarbons in biochar produced from sewage sludge.

Lateral gene transfer (LGT) promotes the proliferation of antibiotic resistance genes (ARGs). However, the lateral transfer efficiency of ARGs in the natural environment is little known. This study explored the lateral transfer of ARG-carrying plasmids to Escherichia coli (i.e., transformation) in the presence of metal oxide nanoparticles (MONPs). The presence of ZnO, Al2O3 and TiO2 nanoparticles (ZnONPs, Al2O3NPs and TiO2NPs, respectively) at concentrations of less than 50 mg L−1 inhibited the lateral transfer of pUC19 plasmid carrying the ampicillin resistance gene into E. coli DH5α in a decreasing degree of Al2O3NP > ZnONP > TiO2NP. The suppressed lateral ARG transfer was not due to the dissolution of metal ions from MONPs, but rather was caused by the binding of MONPs with the phosphate groups and bases of pUC19, as supported by microscopic, spectroscopic and computational evidence. The amount of plasmids bound to MONPs showed a significant negative correlation with the efficiency of ARG transfer, likely because plasmids and MONPs formed aggregates that were blocked out of E. coli cells, thus inhibiting the ARG lateral transfer. Our results provided new insight into the effect of MONPs on the lateral transfer of ARGs and improved our understanding of the ecological risks of plasmid-borne ARGs at the molecular and cellular level.

Plasmid binding to metal oxide nanoparticles inhibited lateral transfer of antibiotic resistance genes

In current studies of noncovalent interactions of polycyclic aromatic hydrocarbons (PAHs) with genetic units, the impact of such interactions on gene transfer has not been explored. In this study, we examined the association of some widely occurring PAHs (phenanthrene, pyrene, benzo[g,h,i]perylene, and other congeners) with antibiotic resistant plasmids (pUC19). Small molecular PAHs (e.g., phenanthrene) bind effectively with plasmids to form a loosely clew-like plasmid-PAH complex (16.5-49.5 nm), resulting in reduced transformation of ampicillin resistance gene (Ampr). The in vitro transcription analysis demonstrated that reduced transformation of Ampr in plasmids results from the PAH-inhibited Ampr transcription to RNA. Fluorescence microtitration coupled with Fourier transform infrared spectroscopy (FTIR) and theoretical interaction models showed that adenine in plasmid has a stronger capacity to sequester small Phen and Pyre molecules via a π-π attraction. Changes in Gibbs free energy (ΔG) suggest that the CT-PAH model reliably depicts the plasmid-PAH interaction through a noncovalently physical sorption mechanism. Considering the wide occurrence of PAHs and antibiotic resistant genes (ARGs) in the environment, our findings suggest that small-sized PAHs can well affect the behavior of ARGs via above-described noncovalent interactions.

Yanzheng Gao

Papers

The Impact of Different Root Exudate Components on Phenanthrene Availability in Soil

Carbon dioxide as a carrier gas and biomass addition decrease the total and bioavailable polycyclic aromatic hydrocarbons in biochar produced from sewage sludge.

Plasmid binding to metal oxide nanoparticles inhibited lateral transfer of antibiotic resistance genes

Noncovalent Binding of Polycyclic Aromatic Hydrocarbons with Genetic Bases Reducing the in Vitro Lateral Transfer of Antibiotic Resistant Genes.

The convertion of sewage sludge to biochar as a sustainable tool of PAHs exposure reduction during agricultural utilization of sewage sludges.