A review of biochars' potential role in the remediation, revegetation and restoration of contaminated soils

Biochars are biological residues combusted under low oxygen conditions, resulting in a porous, low density carbon rich material. Their large surface areas and cation exchange capacities, determined to a large extent by source materials and pyrolysis temperatures, enables enhanced sorption of both organic and inorganic contaminants to their surfaces, reducing pollutant mobility when amending contaminated soils. Liming effects or release of carbon into soil solution may increase arsenic mobility, whilst low capital but enhanced retention of plant nutrients can restrict revegetation on degraded soils amended only with biochars; the combination of composts, manures and other amendments with biochars could be their most effective deployment to soils requiring stabilisation by revegetation. Specific mechanisms of contaminant-biochar retention and release over time and the environmental impact of biochar amendments on soil organisms remain somewhat unclear but must be investigated to ensure that the management of environmental pollution coincides with ecological sustainability.     

Distribution of Airborne polycyclic aromatic hydrocarbons (PAH) in the area of Thessaloniki,Greece

The aim of this research work is to investigate the temporal and regional behaviour of the PAH in the Thessaloniki's area. During a period of six months, airborne particulate matter was collected twice a week and PAH were determined by HPLC. Profiles as well as concentrations of selected cancerogenic PAH differ in some cases from area to area and have characteristic, temporal changes of concentration.     

Effects of biochar and the earthworm Eisenia fetida on the bioavailability of polycyclic aromatic hydrocarbons and potentially toxic elements

Polycyclic aromatic hydrocarbons (PAHs) and potentially toxic elements (PTEs) were monitored over 56 days in calcareous contaminated-soil amended with either or both biochar and Eisenia fetida. Biochar reduced total (449 to 306 mg kg⁻¹) and bioavailable (cyclodextrin extractable) (276 to 182 mg kg⁻¹) PAHs, PAH concentrations in E. fetida (up to 45%) but also earthworm weight. Earthworms increased PAH bioavailability by >40%. Combined treatment results were similar to the biochar-only treatment. Earthworms increased water soluble Co (3.4 to 29.2 mg kg⁻¹), Cu (60.0 to 120.1 mg kg⁻¹) and Ni (31.7 to 83.0 mg kg⁻¹) but not As, Cd, Pb or Zn; biochar reduced water soluble Cu (60 to 37 mg kg⁻¹). Combined treatment results were similar to the biochar-only treatment but gave a greater reduction in As and Cd mobility. Biochar has contaminated land remediation potential, but its long-term impact on contaminants and soil biota needs to be assessed.     

Application of positive matrix factorization to identify potential sources of PAHs in soil of Dalian, China

Soil derived sources of polycyclic aromatic hydrocarbons (PAHs) in the region of Dalian, China were investigated using positive matrix factorization (PMF). Three factors were separated based on PMF for the statistical investigation of the datasets both in summer and winter. These factors were dominated by the pattern of single sources or groups of similar sources, showing seasonal and regional variations. The main sources of PAHs in Dalian soil in summer were the emissions from coal combustion average (46%), diesel engine (30%), and gasoline engine (24%). In winter, the main sources were the emissions from coal-fired boiler (72%), traffic average (20%), and gasoline engine (8%). These factors with strong seasonality indicated that coal combustion in winter and traffic exhaust in summer dominated the sources of PAHs in soil. These results suggested that PMF model was a proper approach to identify the sources of PAHs in soil.     

The application of a mulch biofilm barrier for surfactant enhanced polycyclic aromatic hydrocarbon bioremediation

Lab scale mulch biofilm barriers were constructed and tested to evaluate their performance for preventing the migration of aqueous and surfactant solubilized PAHs. The spatial distribution of viable PAH degrader populations and resultant biofilm formation were also monitored to evaluate the performance of the biobarrier and the prolonged surfactant effect on the PAH degrading microorganism consortia in the biobarrier. Sorption and biodegradation of PAHs resulted in stable operation of the system for dissolved phenanthrene and pyrene during 150 days of experimentation. The nonionic surfactant could increase the solubility of phenanthrene and pyrene significantly. However, the biobarrier itself couldn't totally prevent the migration of micellar solubilized phenanthrene and pyrene. The presence of surfactant and the resultant highly increased phenanthrene or pyrene concentration didn't appear to cause toxic effects on the attached biofilm in the biobarrier. However, the presence of surfactant did change the structural composition of the biofilm.     

Quantification of centimeter-scale spatial variation in PAH, glucose and benzoic acid mineralization and soil organic matter in road-side soil

The aim of the study was to determine centimeter-scale spatial variation in mineralization potential in diffusely polluted soil. To this end we employed a 96-well microplate method to measure the mineralization of ¹⁴C-labeled organic compounds in deep-well microplates and thereby compile mineralization curves for 348 soil samples of 0.2-cm³. Centimeter-scale spatial variation in organic matter and the mineralization of glucose, benzoic acid, and PAHs (phenanthrene and pyrene) was determined for urban road-side soil sampled as arrays (7 × 11 cm) of 96 subsamples. The spatial variation in mineralization was visualized by means of 2-D contour maps and quantified by means of semivariograms. The geostatistical analysis showed that the easily degradable compounds (glucose and benzoic acid) exhibited little spatial variation in mineralization potential, whereas the mineralization was highly heterogeneous for the PAH compounds that require specialized degraders. The spatial heterogeneity should be taken into account when estimating natural attenuation rates.     

Sediment-associated aliphatic and aromatic hydrocarbons in coastal British Columbia, Canada: concentrations, composition, and associated risks to protected sea otters

Sediment-associated hydrocarbons can pose a risk to wildlife that rely on benthic marine food webs. We measured hydrocarbons in sediments from the habitat of protected sea otters in coastal British Columbia, Canada. Alkane concentrations were dominated by higher odd-chain n-alkanes at all sites, indicating terrestrial plant inputs. While remote sites were dominated by petrogenic polycyclic aromatic hydrocarbons (PAHs), small harbour sites within sea otter habitat and sites from an urban reference area reflected weathered petroleum and biomass and fossil fuel combustion. The partitioning of hydrocarbons between sediments and adjacent food webs provides an important exposure route for sea otters, as they consume ∼25% of their body weight per day in benthic invertebrates. Thus, exceedences of PAH sediment quality guidelines designed to protect aquatic biota at 20% of the sites in sea otter habitat suggest that sea otters are vulnerable to hydrocarbon contamination even in the absence of catastrophic oil spills.     

浅析含油污泥处理中石油烃控制指标

石油烃含量是含油污泥处理中必不可少的重要控制指标。文章分析了含油污泥中石油烃组成及主要污染控制要求,介绍了国内外含油污泥处置对石油烃含量的控制现状;依据危险废物鉴别标准的相关规定,以及对原油中芳香族化合物及其多环芳烃含量的研究成果,对采用石油烃指标进行危险废物鉴别做了推论计算。结果认为:含油污泥等固体废物及其处理残余物的石油烃含量≤0.25%,不属于危险废物;石油烃含量介于0.25%～1.7%时,其是否属于危险废物,最终需要进行危险废物鉴别而确定;石油烃含量1.7%,则属于危险废物。     

Toxicity of dispersant application: Biomarkers responses in gills of juvenile golden grey mullet (Liza aurata)

Dispersant use in nearshore areas is likely to increase the exposure of aquatic organisms to petroleum. To measure the toxicity of this controversial response technique, golden grey mullets (Liza aurata) were exposed to mechanically dispersed oil, chemically dispersed oil, dispersant alone in seawater, water-soluble fraction of oil and to seawater as a control treatment. Several biomarkers were assessed in the gills (enzymatic antioxidant activities, glutathione content, lipid peroxidation) and in the gallbladder (polycylic aromatic hydrocarbons metabolites). The significant differences between chemically dispersed oil and water soluble fraction of oil highlight the environmental risk to disperse an oil slick when containment and recovery can be conducted. The lack of significance between chemically and mechanically dispersed oil suggests that dispersant application is no more toxic than the natural dispersion of the oil slick. The results of this study are of interest in order to establish dispersant use policies in nearshore areas.     

根据具体情况优化EPA8310中色谱分离条件

运用Agilent（安捷伦）1200系列高效液相色谱和多环芳烃专用柱ZORBAX Eclipse PAH（4.6×250mm、5μm,P.N.959990-918,S.N.USPAB01066）,对16种多环芳烃化合物混合溶液进行分析,根据具体实验条件优化EPA8310中色谱分离条件并得到了更节省时间、分离效率更好的流动相梯度变化程序。