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Biochar is a carbon-rich material resulting from the pyrolysis of plant and animal biomass. Biochar has a long history as a soil amendment for centuries since the Mayan civilization. Attaining sustainability in agriculture is not easy; however, the addition of biochar may reduce the adverse effects of numerous malpractices in conventional agriculture. Biochar benefits soil physicochemical properties such as soil bulk density, aggregate stability, porosity, water holding capacity and soil organic carbon content. However, it is essential to focus on the negative aspects of biochar in terms of atmospheric emissions during the production and occupational health and safety at the time of use. Still, there are many benefits and detriments of the application of biochar, i.e., the priming effect; thus, this review highlights the importance of further research on the application of biochar as a soil amendment. It has been understood that the lack of long-term field studies in various soils using commercially produced biochar may restrict the knowledge of biochar's true potential and effect on soil nutrient dynamics, microbial structure, and crop yield. Keywords: Land degradation, Biochar, Nutrient retention, Soil quality, Microbial community

Biochars are widely used in the remediation of Cd-contaminated soils. However, changes in the bacterial communities in the rhizosphere contaminated with Cd in response to biochar aging are poorly studied. Addressing this gap in knowledge is important to improving micro-ecological services on healthy growth of plants with mitigation strategies against Cd contamination. An aging experiment (270 days) was conducted with biochars derived from poultry litter and sugar-gum wood added to a Cd-contaminated acid soil. Bacterial communities in the rhizosphere of Brassica rapa and bulk soils were investigated after 1, 90 and 270 days of biochar aging. There was no significant difference (P 0.05) in bacterial Shannon and Simpson indices between the control and biochar treatments. However, compared to the no-Cd control, the addition of Cd decreased the relative abundances of Firmicutes, Chloroflexi and Acidobacteriota but increased those of Actinobacteriota and Proteobacteria. Poultry-litter biochar had the largest effect on bacterial community composition, especially in the rhizosphere. Aging of poultry-litter biochar increased the abundance of Armatimonadota over time more than the sugar-gum-wood biochar, which was attributed to a lower pH and higher bioavailability of Cd in the sugar-gum-wood biochar treatment. The addition of poultry-litter biochar to the contaminated soil mitigated the bioaccumulation of Cd by increasing soil pH and restoring soil bacterial ecology in contaminated acid soils over time.

© 2019 Taylor & Francis Group, LLC. The application of biochars for the remediation of water and soils contaminated with potentially toxic elements (PTEs) has seen a recent growing interest. The mechanisms of chemical immobilization of PTEs with biochars in aqueous media have been well defined. However, immobilization mechanisms by which biochars interact with PTEs in soil matrix are more complex. The biological immobilization mechanisms and their interactions with PTEs in biochar-amended soils are not as well defined. This review presents an overview of factors governing interactions of biochars with PTEs as well as the synergistic effect of biochars and microorganisms in biological immobilization processes. The effectiveness of biochars in improvement of microbial immobilization of PTEs mainly depends on biochar properties, application rates, and soil environments such as organic matter content, clay type and content, pH and redox potential. Although some modified biochars appear to be better than the pristine biochars for immobilization of PTEs, their potential adverse impacts on soil microbial activity should be considered. This review highlights the most common analytical methods to discover molecular interaction mechanisms between biochar and PTEs and future research areas required for the understanding of biochar-PTE interactions in polluted soil systems.

Purpose Purpose of this study is to measure the Vitamin D status of healthy adults and to correlate with their lifestyle and feeding habits. Plasma 25-Hydroxyvitamin D (25(OH)D) is the most common marker of vitamin D status of an individual. Deficiency of vitamin D is defined as the serum level less than 20 ng/mL and insufficiency as 30 ng/mL which can be prevented. Design/methodology/approach Vitamin D status of healthy adults (n = 82), both male and females between the age of 18 – 50 years who were attending to the National Transport Authority, Kandy, Sri Lanka from February to March 2016, was measured and correlated with their lifestyle, feeding habits, etc. Findings The mean total serum D (25(OH)D in this study was 40.15 ± 3.74 nmol/l with the mean value of 42.8 ± 28.8 and 37.5 ± 16.6 for women and men, respectively. The serum calcium levels of both female and male were around 8 mg/dl and the serum total protein was 6.5 and 7 g/dl in women and men, respectively. The serum Vitamin D, calcium and total protein were not statistically significantly different between the sexes. In this study, 84 per cent of the total subjects were normocalcemic, and there was no significant relationship between vitamin D levels and their calcium levels. Research limitations/implications This study demonstrates that there was no statistically significant correlation between the serum vitamin D with age, serum calcium or total proteins. The majority of participants who had exposure to the sunlight more than 30 mins/day had sufficient level of vitamin D and less than 30 min/day exposure had deficiency of vitamin D. Daily intake of multivitamin influenced vitamin D status of the study group. Practical implications These findings will implicate the importance of cultural, feed and social habits for the nutritional status of an individual.and there are no reported studies on vitamin D status with reference to the variation of life style. Social implications It is very important to investigate the factors affecting to the vitamin D status of a population as such, vitamin D insufficiency or deficiency can be prevented. In Sri Lanka, the population is consisting with many ethnic groups, different ethnic groups may find some nutritional problems according to their main cultural habits. Originality/value The objectives of this study are to evaluate the Vitamin D status in a group of healthy adults between 20 and 50 years in both men and women and to find out the correlation of their vitamin D status with their lifestyle and feeding habits, etc.

The effects of biochar aging on heavy-metal bioavailability and microbial activity are not fully understood. This study determined the effect over 270 days of poultry-litter biochar (PBC) and sugar-gum-wood biochar (SBC) on the bioavailability of Cd and microbial activity in acidic soils differing in organic matter content. Soil basal and substrate-induced respirations, microbial properties, Cd bioavailability and plant Cd bioaccumulation were evaluated at 1, 30, 90 and 270 days. The addition of PBC decreased Cd bioaccumulation by 81% and 85% while SBC decreased bioaccumulation by 47% and 56% in high (Chromosol) and low (Sodosol) organic matter soils, respectively, at Day 1. By Day 270, Cd bioaccumulation significantly (P 0.05) increased in SBC-amended soils but decreased in PBC-amended soils. The addition of PBC increased both basal and substrate-induced microbial respirations compared to the other treatments over 270-day aging. However, SBC increased microbial biomass C compared to the PBC after Day 30. Aging decreased microbial respiration and biomass C in biochar-amended soils. It is concluded that Cd bioaccumulation increased in SBC-amended soils during aging whereas the PBC decreased Cd bioaccumulation and that the selection of biochar is important to enhance remediation efficiency in the long term.

© 2020 Elsevier Ltd The capacity of biochars derived from agricultural wastes to remove Cd(II) and Cu(II) from aqueous solution and contaminated mine water was evaluated using laboratory-based batch sorption experiments. To examine immobilization of heavy metals, biochars produced in a commercial-scale mobile pyrolizer from feedstocks: poultry litter; lucerne shoot; vetch shoot; canola shoot; wheat straws; and sugar-gum wood, were tested in a liquid-based system. Biochars were characterized by FTIR, XPS and XRD before and after the mine water treatment. Lucerne biochar had the highest Langmuir sorption capacity of Cd(II) (6.28 mg g−1) and vetch-derived biochar had the highest Cu(II) sorption capacity (18.0 mg g−1) at pH 5.5. All the biochars exhibited higher sorption capacity for Cu(II) than for Cd(II). The smaller ionic radius and higher electronegativity of Cu(II), and the PO43−, CO32− and N-containing functional groups of biochars enhanced their binding affinity. The results demonstrated that poultry litter-derived biochar was effective at removal of the Cd(II) and Cu(II) from mine water up to the levels recommended by the World Health Organisation. The results revealed that precipitation with CO32− and PO43−, complexation with –OH and –COOH groups and electrostatic interaction with O-containing surface functional groups were the main mechanisms involved in the removal of multi-metals by biochars, and that selection of feedstock materials for biochar production is important to maximise remediation of multi-metals in contaminated water.

Woody biochars derived by pyrolyzing Gliricidia sepium at 300°C and 500°C and a waste byproduct of same biomass from a bioenergy industry (BC700) were tested for their effect on soil enzymes activi...

The increase in usage of heavy metals in different industrial activities causes their existence in effluents. Excessive concentrations of these heavy metals pollute soil and water. Heavy metals cause toxicities and other harmful effects not only in humans and animals but also in plants and soil microorganisms. Heavy metals disrupt many biochemical and physiological activities in bacteria, including growth, development, enzyme and hormone production. Indole acetic acid (IAA) is one of the most important hormones in plants, which is secreted by both bacteria and plants. The present study assessed the effects of Ni, Pb and Cu on the growth of Bradyrhizobium japonicum and IAA production. B. japonicum were grown in yeast mannitol broth in a rotary shaker at 100 rpm for 18 h for each variant. Ni, Pb and Cu with concentrations ranging from 2.5–40 mg/L were added to B. japonicum cultures and turbidity was measured at 600 nm. Effects of Ni, Pb and Cu on IAA production were determined by measuring the IAA content with Salkowski method. The metal uptake by B. japonicum was determined in the range of 5–50 mg/L. A lettuce seedling assay was conducted to observe the effect of B. japonicum on plant growth under heavy metal stress. Lettuce seedlings inoculated with the bacterium were spiked with 5–500 mg/L of Ni, Pb and Cu. Shoot and root length, and plant dry biomass were measured after 5 days of germination. Bacterial growth was reduced with the increase of Ni and Cu concentrations. However, there was no significant growth effect with Pb in the considered range. The IAA production also followed the same pattern with Pb and Ni, but in the presence of Cu, IAA content was slightly increased and reached an equilibrium. The growth retardations observed in lettuce in the presence of Pb, Ni and Cu were in the decreasing order of Ni > Cu > Pb. Bacterial inoculation reduced the heavy metal stress and increased the shoot and root lengths of lettuce seedlings. FTIR spectrum of the bacterial biomass showed that amine and nitro groups are responsible in metal sorption process. The Pb-treated bacterial biomass showed a considerable difference in the FTIR spectrum compared to other treatments. According to our results, B. japonicum is sensitive to heavy metal stress with a retardation of growth and IAA production, though it is able to enhance the growth of lettuce seedlings under heavy metal stress.

Crops grown in metal-rich serpentine soils are vulnerable to phytotoxicity. In this study, Gliricidia sepium (Jacq.) biomass and woody biochar were examined as amendments on heavy metal immobilization in a serpentine soil. Woody biochar was produced by slow pyrolysis of Gliricidia sepium (Jacq.) biomass at 300 and 500 °C. A pot experiment was conducted for 6 weeks with tomato (Lycopersicon esculentum L.) at biochar application rates of 0, 22, 55 and 110 t ha−1. The CaCl2 and sequential extractions were adopted to assess metal bioavailability and fractionation. Six weeks after germination, plants cultivated on the control could not survive, while all the plants were grown normally on the soils amended with biochars. The most effective treatment for metal immobilization was BC500-110 as indicated by the immobilization efficiencies for Ni, Mn and Cr that were 68, 92 and 42 %, respectively, compared to the control. Biochar produced at 500 °C and at high application rates immobilized heavy metals significantly. Improvements in plant growth in biochar-amended soil were related to decreasing in metal toxicity as a consequence of metal immobilization through strong sorption due to high surface area and functional groups.

In this study, we investigated the effect of biochar (BC) and fungal bacterial co-inoculation (FB) on soil enzymatic activity and immobilization of heavy metals in serpentine soil in Sri Lanka. A pot experiment was conducted with tomatoes (Lycopersicon esculentum L.) at 1, 2.5, and 5 % (w/w) BC ratios. Polyphenol oxidase, catalase and dehydrogenase activities were determined by idometric, potassium permanganate oxidisable, and spectrophotometric methods, respectively. Heavy metal concentrations were assessed by 0.01 M CaCl2 and sequential extraction methods. An increase in BC application reduced polyphenol oxidase, dehydrogenase, and catalase activity. The application of FB increased soil dehydrogenase activity, with the maximum activity found in 1 % BC700 + FB treatment. Moreover, the CaCl2 extractable metals (Ni, Mn, and Cr) in 5 % BC700 amended soil decreased by 92, 94, and 100 %, respectively, compared to the control. Sequential extraction showed that the exchangeable concentrations of Ni, Mn, and Cr decreased by 55, 70, and 80 % in 5 % BC700, respectively. Results suggest that the addition of BC to serpentine soil immobilizes heavy metals and decreases soil enzymatic activities. The addition of FB to serpentine soil improves plant growth by mitigating heavy metal toxicity and enhancing soil enzymatic activities.

Pyrolysis is the foremost thermal conversion process that can be successfully used to transform biomaterials into a value-added product. The estimated biodegradable portion is prominent and denotes as 60% from total waste generation in Asian developing countries. There have been several studies on exploring the pyrolysis of complex organic fraction of municipal solid waste (MSW) streams as a sustainable MSW management technique. The objective of this research was to evaluate physicochemical characteristics of MSW biochar (MSW-BC) produced from organic MSW to observe its potential for landfill contaminant removal with case studies from Sri Lanka. Biochar was pyrolyzed from the MSW in an onsite pyrolyzer. For physicochemical properties of biochar, pH, point of zero charge, electrical conductivity, proximate analysis, ultimate analysis, heavy metal composition, bioavailable heavy metal composition and BET surface area were acquired. In addition, surface functional groups and structural identification were determined by FTIR analysis and scanning electron microscopy (SEM) analysis, respectively. Adsorption capacities for the pollutants (benzene and toluene) were examined by batch sorption experiments. Furthermore, sorption isotherms were fitted using non-linear models for better understanding of the sorption capacities of the materials. Ultimate analysis data suggested high-temperature pyrolysis of MSW. Further, low values for both H/C and polarity index depict the strongly carbonized and highly aromatic structure in BC. Additionally, FTIR suggested a loss of labile, aliphatic compounds and functional groups during pyrolysis and the formation of more recalcitrant, aromatic constituents, whereas BET and SEM data revealed a well-developed porous structure and surface properties, which indicates MSW-BC to be a potential sorbent. Further, the reported total and bioavailable heavy metal content was low in MSW-BC; hence, it can be easily mixed with compost and used as a fertilizer. At the same time, MSW-BC will potentially be used to remediate heavy metals in the landfill leachate. Therefore, MSW-BC shows high potential to be used as a material to remediate contaminants simultaneously that minimizes MSW volume. Thus, conversion of MSW to BC and chemical and thermal modification of MSW-BC would allow effective engineering to optimize their properties as a potential material in landfill covers and permeable reactive barriers and integrate in leachate treatment techniques.

Background Iodine is an essential micronutrient used by the thyroid gland in the production of thyroid hormones. Both excessive and insufficient iodine intakes can cause thyroid diseases thus harmful to the human body. Inadequate iodine intake by human body causes Iodine Deficiency Disorders (IDD) and hypothyroidism. Excessive iodine intake causes Iodine Induced Hyperthyroidism (IIH). Universal Salt Iodization (USI) is the most effective way of preventing IDD. This study determined the concentrations of iodine species in commercial edible salt products, the stability of iodine at different conditions and iodine exposure at the consumer level. Methods The iodine contents of six commercial edible iodized salts were determined qualitatively and quantitatively for both iodide and iodate. Thereafter, the first three products of highest iodine contents, the stability of iodide at exposed to air and heat was measured after 24 hours. Risk assessment of exposure was done at four levels considering the WHO estimation. Results Results revealed that all of the salt products have excess iodine that is above the fortification level of 15–30 mg kg−1 level in Sri Lanka. Iodide stability was reduced at the average percentages of 13.1, 10.7 and 11.3. The iodate loss percentages were 0, 5.7 and 0 at open air. The iodide loss percentages at the temperature of 50 °C were 4.6, 7.8 and 8.6 while at 100 °C, loss percentages were 11.1, 11.4 and 15.9 for the same salt products. The iodine exposure at lower consumption during cooking ranged 244.4–432.2 μg/day while 325.9–576.3 μg/day for medium consumption, 407.4–720.4 μg/day for moderate high salt consumptions and 488.8–864.4 μg/day for high salt consumptions. As a total 95.8 % cases can cause IIH and only 4.1 % of them can provide optimal iodine nutrition in a population. Iodine exposure without cooking ranged 305.5–540.3 μg/day for low salt consumption, 407.4–720.4 μg/day for medium consumption and 509.2–900.5 μg/day for moderate high consumption and 611.1–1080.6 μg/day for high salt consumptions. Conclusions All of the incidents (100 %) of consumption without cooking at the household level can cause excessive iodine intake and IIH in a population.

Used bullets and fragments have been known as a primary source of heavy metals/metalloids in shooting ranges. Once the bullets perch on soils, toxic metals/metalloids can be released into the surrounding environment and subsequently transformed into a wide range of species through oxidation and deterioration of the pellets and become bioavailable in soils. Various physicochemical techniques have been adopted for the elimination of heavy metals from the shooting range soil, and those methods are highly time-consuming and expensive. Therefore in this chapter, we comprehensively discuss the phytoremediation technique as an alternative method to remediate shooting range soils. The phytoremediation of shooting ranges is not an easy task due to multi-metals/metalloids contamination. At this instant, only a limited number of plant species such as Vetiveria zizanoides, Helianthus annuus, Zea maize, Pisum sativum, Helianthus annuus, etc. are experimented for shooting range soil. Therefore, identification of potentially phytoremedial plant species is very important. However, not many cases have focused on simultaneous metals and metalloid removal. Transgenic plants can be successfully employed to promote phytoremediation of metals and metalloids in shooting range soil. Overall, phytoremediation would be highly applicable to remediate toxic metals/metalloids in shooting range soils.

This study was conducted to understand the role of bacterial–fungal interactions on heavy metal uptake by Zea mays plants. A pot experiment was conducted for 90 days with Z. mays in serpentine soil inoculated with a Gram-negative bacterium, fungus (Aspergilllus sp.) and both microbes to determine the effects of inoculation on nickel, manganese, chromium and cobalt concentrations in plant tissue and soil. Soil nutrients and soil enzyme activities were measured to determine the effect of inoculations on soil quality. Inoculation of microorganisms increased shoot and root biomass, and the maximum biomass was in the bacterial–fungal inoculation. This could be due to the solubilisation of phosphate and production of indole acetic acid. Although the combination treatment contributed to an increase in heavy metal uptake in Z. mays plants, the lowest translocation was observed in the combination treatment. Moreover, the soil available nitrogen, available phosphorous and total organic carbon content were increased with the microbial inoculation. Similarly, the soil dehydrogenase activity was higher as a result of microbial inoculation, whereas the highest dehydrogenase activity was reported in the combination inoculation. This study confirms the synergistic effect of bacterial–fungal inoculation as a soil-quality enhancer and as a plant-growth promoter in the presence of heavy metals.

Soil quality degradation is one of the most widespread phenomena for declining agricultural productivity throughout the world. It has been estimated that more than 40% of agricultural lands have been already become marginal due to mismanagement of soil. Biochar is a carbon rich product of a thermochemical conversion of biomass to be recognized as a beneficial soil amendment. It is not a novel soil amendment and history goes back to Mayan civilization called “Terra preta” soil. Due to the high fertility of these Amazon basin soils, many researchers in the world were interested in properties and application of biochar. This review gives an overview of agricultural benefits of biochar as a soil amendment. However, still there are many pros and cons of the application of biochar and this article will highlight the importance of further researches on the application of biochar as a soil amendment.