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Background and aims: Plant uptake of active pharmaceutical ingredients (APIs) is increasingly leading to concerns about their potential exposure to humans and wildlife via dietary intake. Due to the extraordinary ability of biochars to bind organic compounds, plant uptake experiments were conducted to assess the effect of soil-amendment of three different biochars on the uptake of APIs from spiked soil. Methods: Pot experiments were undertaken to assess the extent of sorption and corresponding bioaccessibility of two APIs (carbamazepine - CBZ and propranolol -PRL) to ryegrass ( Lolium perenne) grown in an API-spiked loamy sand, with and without biochar amendment (5 t/ha equivalent). The soil was amended with three different biochars produced from eucalyptus wood and wheat residues. Results: Both APIs were taken up by ryegrass, with CBZ preferentially accumulated (14.3 mg/kg CBZ, 3.8 mg/kg PRL in unamended soil) due to its comparatively high concentration in porewater. Soil amendment with biochars increased partitioning of the two APIs by up to three- fold, with corresponding decreases in porewater (34-72 % of unamended soil) and plant tissue (17-64 %) concentrations. Conclusions: Biochars were effective in reducing the uptake of APIs into plant tissues from a contaminated soil and may be effective in the management of API residues in contaminated soils. [ABSTRACT FROM AUTHOR]

Abstract: We evaluated wheat straw biochar produced at 450°C for its ability to influence bioavailability and persistence of two commonly used herbicides (atrazine and trifluralin) with different modes of action (photosynthesis versus root tip mitosis inhibitors) in two contrasting soils. The biochar was added to soils at 0%, 0.5% and 1.0% (w/w) and the herbicides were applied to those soil-biochar mixes at nil, half, full, two times, and four times, the recommended dosage (H4). Annual ryegrass (Lolium rigidum) was grown in biochar amended soils for 1month. Biochar had a positive impact on ryegrass survival rate and above-ground biomass at most of the application rates, and particularly at H4. Within any given biochar treatment, increasing herbicide application decreased the survival rate and fresh weight of above-ground biomass. Biomass production across the biochar treatment gradient significantly differed (p <0.01) and was more pronounced in the case of atrazine than trifluralin. For example, the dose–response analysis showed that in the presence of 1% biochar in soil, the value of GR50 (i.e. the dose required to reduce weed biomass by 50%) for atrazine increased by 3.5 times, whereas it increased only by a factor of 1.6 in the case of trifluralin. The combination of the chemical properties and the mode of action governed the extent of biochar-induced reduction in bioavailability of herbicides. The greater biomass of ryegrass in the soil containing the highest biochar (despite having the highest herbicide residues) demonstrates decreased bioavailability of the chemicals caused by the wheat straw biochar. This work clearly demonstrates decreased efficacy of herbicides in biochar amended soils. The role played by herbicide chemistry and mode of action will have major implications in choosing the appropriate application rates for biochar amended soils. [Copyright &y& Elsevier]

We are racing to manage a phenomenally increasing volume of organic wastes from urban, industrial and agricultural entities. Composting is one of the preferred ways to convert biodegradable wastes into nutrient-rich soil conditioners. The age-old technique of composting process is being improved with innovative scientific means. Biochar, a widely studied soil amendment, is a carbonaceous material that can hold nutrients from endogenic/exogenic sources. Biochar-compost, a biochar-complemented compost, may provide a wide range of benefits expected from both materials. Compost and biochar can improve physicochemical and microbiological attributes of soils by supplying labile and stable carbons, and nutrients. Compost may also supply beneficial microbes. This means biochar-compost is a synergic soil amendment that can improve soil quality, increase crop production, and remediate contaminated soils. Having stable carbon, large reactive surface with nutrient loads, biochar can interact widely with organic biomass and modify physicochemical and-microbial states during a composting process while making biochar-compost. Production and application methods of biochar, compost and biochar-compost are covered for agricultural and contaminated soils. Metal and organic contaminations are also discussed. A case study on making and field-testing a mineral-enhanced biochar and a biochar-compost to improve rice yield, is presented at the end. [ABSTRACT FROM AUTHOR]

Biochar is produced by thermal decomposition of biomass under oxygen-limited conditions (pyrolysis), and it has received attention in soil remediation and waste disposal in recent years. The characteristics of biochar are influenced mainly by the preparation temperature and biomass. Higher pyrolysis temperature often results in the increased surface area and carbonized fraction of biochar leading to high sorption capability for pollutants. Biochars derived from various source materials show different properties of surface area, porosity and the amount of functional groups which are important concerning on the effect of biochar. Biochar has been proved to be effective in improving soil properties and increasing crop biomass. It has also been suggested that it can even enhance crop resistance to disease. Biochar has recently been used to remediate soil with both heavy metal and organic pollutants. The mechanism is electrostatic interaction and precipitation in the case of heavy metal, and the surface adsorption, partition and sequestration in the case of organic contaminants. However, application of biochar in soil has been shown to result in decreased efficacy of pesticides, which indicates a trade-off between the potentially promising effect of biochar on pesticide remediation and its negative effect on pesticide efficacy. While arguments on the effectiveness of biochar appear sound, further research is needed prior to widespread application of biochar in soil remediation. [ABSTRACT FROM AUTHOR]

The transport and retention of Escherichia coli and bacteriophages (PRD1, MS2 and ФX174), as surrogates for human pathogenic bacteria and viruses, respectively, were studied in the sand that was amended with several types of biochar produced from various feedstocks. Batch and column studies were conducted to distinguish between the role of attachment and straining in microbe retention during transport. Batch experiments conducted at various solution chemistries showed negligible attachment of viruses and bacteria to biochar before or after chemical activation. At any given solution ionic strength, the attachment of viruses to sand was significantly higher than that of biochar, whereas bacteria showed no attachment to either sand or biochar. Consistent with batch results, biochar addition (10% w / w ) to sand reduced virus retention in the column experiments, suggesting a potential negative impact of biochar application to soil on virus removal. In contrast, the retention of bacteria was enhanced in biochar-amended sand columns. However, elimination of the fine fraction (< 60 μm) of biochar particles in biochar-amended sand columns significantly reduced bacteria retention. Results from batch and column experiments suggest that land application of biochar may only play a role in microbe retention via straining, by alteration of pore size distribution, and not via attachment. Consequently, the particle size distribution of biochar and sediments is a more important factor than type of biochar in determining whether land application of biochar enhances or diminishes microbial retention. [ABSTRACT FROM AUTHOR]

Two experiments were conducted where three biochars, made from macadamia nutshell (MS), hardwood shaving (WS) and chicken litter (CL), were co-composted with chicken manure and sawdust, and also incubated with a chicken litter based commercial compost. Biochars were added at the rates of 5% and 10% in the co-composting and 10% and 20% in the incubation experiment. The rates of biochar had no consistent effect on the change in element contents of composted- or incubated-biochars. The biochar C demonstrated recalcitrance in both composting and incubation systems. Composting increased the CEC of biochars probably due to thermophilic oxidation. The increases in CEC of WS and CL were 6.5 and 2.2 times, respectively, for composting. Translocation of elements, between biochar and compost medium, occurred in both directions. In most cases, biochars gained elements under the influence of positive difference of concentrations (i.e., when compost medium had higher concentration of elements than biochar), while in some cases they lost elements despite a positive difference. Biochar lost some elements (WS: B; CL: B, Mg and S) under the influence of negative difference of concentrations. Some biochars showed strong affinity for B, C, N and S: the concentration of these elements gained by biochars surpassed the concentration in the respective composting medium. The material difference in the biochars did not have influence on N retention: all three netbag-biochars increased their N content. The cost of production of biochar-compost will be lower in co-composting than incubation, which involves two separate processes, i.e., composting and subsequent incubation. [ABSTRACT FROM AUTHOR]