Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 91
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Chemosphere ; : 134942, 2022 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-35577128

RESUMO

Chromium (Cr) contamination in soil and water poses high toxicity risks to organisms and threatens food and water security worldwide. Biochar has emerged as a promising material for cleaning up Cr contamination owing to biochar's strong capacity to immobilize Cr. This paper synthesizes information on biochar modification for the efficient remediation of Cr contamination in soil and water, and critically reviews mechanisms of Cr adsorption on pristine and modified biochars. Biochar modification methods include physical activation via ball milling or ultraviolet irradiation, chemical activation via magnetization, alkali/acid treatment, nano-fabrication or loading of reductive agents, and biological activation via integrating biochars with microorganisms and their metabolites. Modified biochars often have multi-fold enhancement in Cr adsorption/reduction capacity than pristine biochars. Iron (Fe)-supported magnetic biochars have the most promising Cr removal abilities with high reusability of the biochars. Pre-pyrolysis modification with Fe could load Fe3O4 micro-/nanoparticles on biochars, and increase the surface area and electrostatic attraction between chromate anions and biochar surfaces, and reduce Cr(VI) to Cr(III). Post-pyrolysis modification could enrich oxygen-containing functional groups such as CO and -OH on biochar surfaces and promote Cr reduction and adsorption. Future research directions for Cr mitigation using advanced biochar products are discussed in this review.

2.
Bioresour Technol ; 354: 127245, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35489572

RESUMO

Elevated metal (e.g., alkali metals) and ash contents can negatively impact the use of biomass-derived solid fuels, including hydrochars, in clean energy generation. The effects of nitric acid modification on those and other properties (combustion, fuel and thermal) were studied for hydrochars produced at three temperatures from four feedstocks. Through side-chain oxidation and surface protonation, nitric acid significantly leached metals from pristine hydrochars to a maximum of five order and increased their burnout temperature by 9-41%, but its effect on ash content, gross calorific values and ignition temperature depended on feedstock type and carbonization temperature. Ignition temperature increased by > 2 times for modified manure pellet hydrochar produced at 300 °C. The combustion characteristics index for the hydrochars was above the minimum benchmark (2 × 10-7 %2 min-2 °C-3) for a typical solid fuel. Therefore, nitric acid can effectively improve hydrochar's combustion and fuel properties and reduce slagging in industrial boilers.


Assuntos
Esterco , Ácido Nítrico , Biomassa , Carbono , Temperatura
3.
Sci Total Environ ; 830: 154753, 2022 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-35339555

RESUMO

Nitrous oxide and ammonia emissions from farmland need to be abated as they directly or indirectly affect climate warming and crop yield. We conducted a two-year field experiment to investigate the effect of biochar applied at two rates (no biochar application vs. biochar applied at 10 t ha-1) on gaseous nitrogen (N) losses (N2O emissions and NH3 volatilization), plant N uptake, residual soil mineral N, and peanut (Arachis hypogaea L.) yield under three irrigation regimes: furrow irrigation (FI), drip irrigation (DI), and mulched drip irrigation (MDI). We found that MDI reduced residual (post-harvest) soil mineral N, cumulative N2O emissions, and yield-scaled N2O emissions as compared to FI. Biochar application increased residual soil NO3--N and decreased yield-scaled N2O emissions as compared with the control without biochar application. Under the three irrigation regimes, biochar application decreased cumulative NH3 volatilization and increased plant N uptake and yield compared with the control. Biochar application improved the sustainability of peanut production and could be used to alleviate the environmental damage associated with gaseous N emissions. Where possible, biochar application under MDI in peanut fields is recommended as a management strategy to minimize gaseous N losses.

4.
Artigo em Inglês | MEDLINE | ID: mdl-35270711

RESUMO

To achieve carbon (C) neutrality and mitigate climate change, it is crucial to understand how converting natural forests to agricultural plantations influences soil organic C (SOC) mineralization. In this study, we investigated the impact of converting evergreen broadleaf forests (EBF) to extensively managed Moso bamboo (Phyllostachys edulis (Carriere) J. Houzeau) plantations (MBP) in subtropical China on SOC mineralization rate; the concentrations of labile SOC fractions such as dissolved organic C (DOC), microbial biomass C (MBC), and readily oxidizable C (ROC); the activities of C-degrading enzymes (cellobiohydrolase and phenol oxidase); and the abundance of C-degrading enzyme-encoding genes (cbhI and lcc). Three paired soil samples were taken from the surface layer (0-20 cm) of adjacent EBF-MBP sites in Anji County, Zhejiang province. Results showed that converting EBF to MBP significantly increased the SOC mineralization rate as well as soil pH, MBC, cellobiohydrolase, and phenol oxidase activities, and cbhI gene abundance, but did not change other soil properties described above. In addition, structural equation modelling (SEM) showed that the conversion increased SOC mineralization rate through increasing soil pH, cbhI gene abundance, MBC, and cellobiohydrolase and phenol oxidase activities. Our novel finding that converting EBF to extensively managed MBP enhanced SOC mineralization via increasing the activities of C-degrading enzymes suggests that C-degrading enzymes were a key factor regulating SOC mineralization in the extensively managed subtropical bamboo plantations.


Assuntos
Calcinose , Solo , Carbono , Celulose 1,4-beta-Celobiosidase , Florestas , Monofenol Mono-Oxigenase , Poaceae , Solo/química
5.
J Hazard Mater ; 427: 128176, 2022 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-34996001

RESUMO

Examining transcriptomic and metabolic responses of earthworms to microplastic-contaminated soil is critical for understanding molecular-level toxicity of microplastics; yet very little research on this topic exists. We investigated influences of environmentally relevant concentrations (ERC) of polypropylene (PP) and polyethylene (PE) microplastic-contaminated soil on earthworms at the transcriptomic, metabolic, tissue and whole-body levels to study their molecular toxicity. The addition of PP and PE at ERC induced oxidative stress on earthworms, as indicated by the high enrichment of glutathione metabolism and increased glutamine at the transcriptomic and metabolic levels. Digestive and immune systems of earthworms were damaged according to the injuries of the intestinal epithelium, partial shedding of chloragogenous tissues and unclear structure of coelom tissues, which were confirmed by pathway analysis at the transcriptomic level. Significant enrichment of arachidonic acid and glycerolipid metabolisms indicated that PP and PE disturbed the lipid metabolism in earthworms. Significantly increased betaine and myo-inositol, and decreased 2-hexyl-5-ethyl-3-furansulfonate suggested that PP and PE caused differences in osmoregulation extent. In conclusion, most similar responses of earthworm might result from special size rather than type effects of PP and PE microplastics. Contamination of soils with microplastics even at ERC has health risks to earthworms; therefore, proper management of microplastics to reduce their input to the environment is key to reducing the health risks to soil fauna.


Assuntos
Oligoquetos , Poluentes do Solo , Animais , Microplásticos , Oligoquetos/genética , Plásticos/toxicidade , Polietileno/toxicidade , Polipropilenos/toxicidade , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade , Transcriptoma
6.
Sci Total Environ ; 809: 151120, 2022 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-34756904

RESUMO

Biochar has been widely studied as an adsorbent for the removal of contaminants from wastewater due to its unique characteristics, such as having a large surface area, well-distributed pores and high abundance of surface functional groups. Critical review of the literature was performed to understand the state of research in utilizing biochars for industrial wastewater remediation with emphasis on pollutants that co-exist in wastewater from several industrial activities, such as textile, pharmaceutical and mining industries. Such pollutants include organic (such as synthetic dyes, phenolic compounds) and inorganic contaminants (such as cadmium, lead). Multiple correspondence analyses suggest that through batch equilibrium, columns or constructed wetlands, researchers have used mechanistic modelling of isotherms, kinetics, and thermodynamics to evaluate contaminant removal in either synthetic or real industrial wastewaters. The removal of organic and inorganic contaminants in wastewater by biochar follows several mechanisms: precipitation, surface complexation, ion exchange, cation-π interaction, and electrostatic attraction. Biochar production and modifications promote good adsorption capacity for those pollutants because biochar properties stemming from production were linked to specific adsorption mechanisms, such as hydrophobic and electrostatic interactions. For instance, adsorption capacity of malachite green ranged from 30.2 to 4066.9 mg g-1 depending on feedstock type, pyrolysis temperature, and chemical modifications. Pyrolyzing biomass at above 500 °C might improve biochar quality to target co-existing pollutants. Treating biochars with acids can also improve pollutant removal, except that the contribution of precipitation is reduced for potentially toxic elements. Studies on artificial intelligence and machine learning are still in their infancy in wastewater remediation with biochars. Meanwhile, a framework for integrating artificial intelligence and machine learning into biochar wastewater remediation systems is proposed. The reutilization and disposal of spent biochar and the contaminant release from spent biochar are important areas that need to be further studied.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Adsorção , Inteligência Artificial , Carvão Vegetal , Poluentes Químicos da Água/análise
7.
Sci Total Environ ; 806(Pt 1): 150557, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34582865

RESUMO

Plant and soil elemental ratios of carbon (C), nitrogen (N) and phosphorus (P) play a central role in shaping the composition and structure of microbial communities. However, the relationships between plant and soil elemental C:N:P ratios and microbial diversity are still poorly understood. Here, we evaluated the effects of C:N:P ratios in plant-soil systems on microbial diversity in a chronosequence of restored grasslands (1, 5, 10, 15, 25, and 30 years since restoration) on the Loess Plateau. We found that C and N concentrations, C:N and C:P ratios in leaf, root, soil and microbial biomass, bacterial and fungal diversity (Shannon-Wiener index) gradually increased with year since grassland restoration. Microbial C:N:P ratios ranged from 17.8:4.5:1 to 24.3:6.6:1, and C:P ratio increased from 17.8:1 at the 1-year site to 24.3:1 at the 30-year site, indicating the increasing P limitation for soil microorganisms during grassland development. Soil microbial diversity increased with root, soil, and microbial C and N concentrations, and decreased with P concentration (p < 0.05). Structural equation modeling indicated that soil and microbial C:N and N:P ratios had the greatest influences on soil bacterial and fungal diversity, and elemental C:N:P ratios had a greater effect on soil fungal than bacterial diversity. Our findings emphasize the importance of elemental C:N:P ratios on soil microbial diversity, which is critical for formulating policies for sustainable biodiversity conservation in terrestrial ecosystems.


Assuntos
Microbiota , Solo , Carbono/análise , China , Pradaria , Nitrogênio/análise , Plantas , Microbiologia do Solo
8.
Bioresour Technol ; 344(Pt B): 126316, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34798246

RESUMO

Nitric acid activation (NA-A) effects on the surface properties, mineral phases and element compositions of biochars produced from four feedstocks at three temperatures were evaluated. NA-A increased biochar thermal stability, but its effect on ash content and surface area was feedstock-dependent, with ash content in manure pellet biochars less affected due to a high quartz content. Apart from the manure pellet biochars and the sawdust biochar produced at 400 °C, NA-A decreased the surface area of biochars by up to 100% due to reduced pore volume. Nitric acid significantly leached elements such as potassium from biochars due to protonation and their reactions with several mineral phases, such as sylvite, on the biochars (p < 0.05). This study shows that mineral phases and element compositions of nitric acid-activated biochars were driven more by the feedstock type than the pyrolysis temperature and the derived biochars would be poor adsorbents.


Assuntos
Ácido Nítrico , Pirólise , Carvão Vegetal , Propriedades de Superfície , Temperatura
9.
Sci Total Environ ; 806(Pt 3): 151337, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34743889

RESUMO

Applying organic amendments to soil can increase soil organic carbon (SOC) storage and reduce greenhouse gas (GHG) emissions generated by agriculture, helping to mitigate climate change. However, it is necessary to determine which type of amendment produces the most desirable results. We conducted a 3-y field study comparing one-time addition of manure compost and its biochar derivative to a control to assess their effects on SOC and GHG emissions at ten annually cropped sites in central Alberta, Canada. Manure compost and biochar were applied at equivalent carbon rates (7 Mg ha-1) and tilled into the surface 10 cm of soil. Two years post-treatment, biochar addition increased surface (0-10 cm) SOC by 12 and 10 Mg ha-1 relative to the control and manure addition, respectively. Therefore, biochar addition led to the sequestration of SOC at a rate of 2.5 Mg ha-1 y-1 relative to the control. No treatment effect on deeper (10-100 cm) or cumulative SOC was found. In 2018 and 2019, manure addition increased cumulative GHG (sum of CO2, CH4, and N2O) emissions by 33%, on average, due to greater CO2 emissions relative to both the control and biochar addition. In contrast, in 2020, biochar addition reduced cumulative GHG emissions by an average of 21% due to lower CO2 emissions relative to both the control and manure addition. Our study shows that the application of biochar, rather than its manure compost feedstock, increased surface SOC sequestration and had either no effect on (first two years) or reduced GHG emissions (year three) relative to the control. We recommend that policy and carbon sequestration initiatives focus on optimizing biochar production-application systems to fully realize the potential of biochar application as a viable climate change mitigation practice in agriculture.


Assuntos
Gases de Efeito Estufa , Agricultura , Alberta , Carbono , Carvão Vegetal , Produtos Agrícolas , Esterco/análise , Óxido Nitroso/análise , Solo
10.
Innovation (N Y) ; 2(4): 100180, 2021 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-34877561

RESUMO

Global development has been heavily reliant on the overexploitation of natural resources since the Industrial Revolution. With the extensive use of fossil fuels, deforestation, and other forms of land-use change, anthropogenic activities have contributed to the ever-increasing concentrations of greenhouse gases (GHGs) in the atmosphere, causing global climate change. In response to the worsening global climate change, achieving carbon neutrality by 2050 is the most pressing task on the planet. To this end, it is of utmost importance and a significant challenge to reform the current production systems to reduce GHG emissions and promote the capture of CO2 from the atmosphere. Herein, we review innovative technologies that offer solutions achieving carbon (C) neutrality and sustainable development, including those for renewable energy production, food system transformation, waste valorization, C sink conservation, and C-negative manufacturing. The wealth of knowledge disseminated in this review could inspire the global community and drive the further development of innovative technologies to mitigate climate change and sustainably support human activities.

11.
Glob Chang Biol ; 27(24): 6512-6524, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34510656

RESUMO

Soil gross nitrification (GN) is a critical process in the global nitrogen (N) cycle that results in the formation of nitrate through microbial oxidation of ammonium or organic N, and can both increase N availability to plants and nitrous oxide emissions. Soil GN is thought to be mainly controlled by soil characteristics and the climate, but a comprehensive analysis taking into account the climate, soil characteristics, including microbial characteristics, and their interactions to better understand the direct and indirect controlling factors of GN rates globally is lacking. Using a global meta-analysis based on 901 observations from 330 15 N-labeled studies, we show that GN differs significantly among ecosystem types, with the highest rates found in croplands, in association with higher pH which stimulates nitrifying bacteria activities. Autotrophic and heterotrophic nitrifications contribute 63% and 37%, respectively, to global GN. Soil GN increases significantly with soil total N, microbial biomass, and soil pH, but decreases significantly with soil carbon (C) to N ratio (C:N). Structural equation modeling suggested that GN is mainly controlled by C:N and soil total N. Microbial biomass and pH are also important factors controlling GN and their effects are similar. Precipitation and temperature affect GN by altering C:N and/or soil total N. Soil total N and temperature drive heterotrophic nitrification, whereas C:N and pH drive autotrophic nitrification. Moreover, GN is positively related to nitrous oxide and carbon dioxide emissions. This synthesis suggests that changes in soil C:N, soil total N, microbial population size, and/or soil pH due to anthropogenic activities may influence GN, which will affect nitrate accumulation and gaseous emissions of soils under global climate and land-use changes.


Assuntos
Nitrificação , Solo , Ecossistema , Nitrogênio/análise , Óxido Nitroso/análise , Microbiologia do Solo
12.
Sci Total Environ ; 801: 149717, 2021 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-34425443

RESUMO

Despite fresh and pyrogenic organic matter have been widely used as amendments to improve soil organic carbon (SOC) storage, mineralization that links to C quality and soil temperature, microbial community composition and enzyme activity remain poorly understood. This study aims to explore the effects of amendments (bamboo leaves and its biochar) and incubation temperature on mineralization, and disentangle the relationships of SOC mineralization with chemical composition of SOC, labile organic C, microbial community composition, and activities of enzymes in a subtropical bamboo forest soil. Results showed that cumulative soil CO2 emissions ranked as bamboo leaf (Leaf) > bamboo leaf biochar (Biochar) > Control, regardless of the incubation temperature. Compared to the control, the Leaf treatment markedly increased, whereas the Biochar treatment decreased, the temperature sensitivity of SOC mineralization (P < 0.05). The cumulative soil CO2 emission was positively correlated (P < 0.05) with water-soluble organic C (WSOC), microbial biomass C (MBC), O-alkyl C and alkyl C contents, and activities of ß-glucosidase and dehydrogenase, but negatively correlated (P < 0.01) with aromatic C content, regardless of the incubation temperature. This indicated that the lower SOC mineralization rate and lower temperature sensitivity in the Biochar (cf. Leaf) treatment were intimately associated with the lower WSOC, MBC, O-alkyl C content, and ß-glucosidase and dehydrogenase activities, and higher aromatic C content in the Biochar. The high relative abundance of bacteria relating SOC mineralization included Rhizobiales, Sphingobacteriales and JG30-KF-AS9, whereas that of fungi included Eurotiales, Sordariales, Agaricales and Helotiales. Our results revealed that the application of pyrogenic organic matter, as compared to the application of fresh organic matter, can reduce SOC mineralization and its temperature sensitivity in a subtropical forest soil by limiting the availability of C and microbial activity, and thus has a great potential for maintaining soil carbon stock in subtropical forest ecosystems.


Assuntos
Microbiota , Solo , Carbono , Carvão Vegetal , Florestas , Microbiologia do Solo
13.
Glob Chang Biol ; 27(22): 5950-5962, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34407262

RESUMO

Soil gross nitrogen (N) mineralization (GNM), a key microbial process in the global N cycle, is mainly controlled by climate and soil properties. This study provides for the first time a comprehensive analysis of the role of soil physicochemical properties and climate and their interactions with soil microbial biomass (MB) in controlling GNM globally. Through a meta-analysis of 970 observations from 337 published papers from various ecosystems, we found that GNM was positively correlated with MB, total carbon, total N and precipitation, and negatively correlated with bulk density (BD) and soil pH. Our multivariate analysis and structural equation modeling revealed that GNM is driven by MB and dominantly influenced by BD and precipitation. The higher total N accelerates GNM via increasing MB. The decrease in BD stimulates GNM via increasing total N and MB, whereas higher precipitation stimulates GNM via increasing total N. Moreover, the GNM varies with ecosystem type, being greater in forests and grasslands with high total carbon and MB contents and low BD and pH compared to croplands. The highest GNM was observed in tropical wet soils that receive high precipitation, which increases the supply of soil substrate (total N) to microbes. Our findings suggest that anthropogenic activities that affect soil microbial population size, BD, soil substrate availability, or soil pH may interact with changes in precipitation regime and land use to influence GNM, which may ultimately affect ecosystem productivity and N loss to the environment.


Assuntos
Nitrogênio , Solo , Carbono , Ecossistema , Nitrogênio/análise , Microbiologia do Solo
14.
Environ Pollut ; 288: 117721, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34247001

RESUMO

Both soil microbial nitrate (NO3--N) immobilization and denitrification are carbon (C)-limited; however, to what extent organic C addition may increase NO3--N immobilization while stimulate denitrification nitrogen (N) loss remains unclear. Here, 15N tracing coupled with acetylene inhibition methods were used to assess the effect of adding glucose, wheat straw and peanut straw on NO3--N immobilization and denitrification under aerobic conditions in an upland soil, in which NO3--N immobilization has been previously demonstrated to be negligible. The organic C sources (5 g C kg-1 soil) were added in a factorial experiment with 100, 500, and 1000 mg N kg-1 soil (as K15NO3) in a 12-d laboratory incubation. Microbial NO3--N immobilization in the 12-d incubation in the three N treatments was 5.5, 7.7, and 8.2 mg N kg-1 d-1, respectively, in the glucose-amended soil, 5.9, 4.2, and 2.4 mg N kg-1 d-1, respectively, in the wheat straw-amended soil, and 4.9, 5.1 and 4.4 mg N kg-1 d-1, respectively, in the peanut straw-amended soil. Therefore, under sufficient NO3--N substrate, the higher microbial NO3--N immobilization in the glucose than in the crop residue treatments was likely due to the slow decomposition of the latter that provided low available C. The 15N recovery in the N2O + N2 pool over the12-day incubation was <2% for all treatments, indicating negligible denitrification N loss due to low denitrification rates in the aerobic incubation in spite of increasing C availability. We conclude that external C addition can enhance microbial NO3--N immobilization without causing large N losses through denitrification. This has significant implications for reducing soil NO3--N accumulation by enhancing microbial NO3--N immobilization through increasing C inputs using organic materials and subsequently mitigating nitrate pollution of water bodies.


Assuntos
Nitrogênio , Solo , Desnitrificação , Nitratos , Nitrogênio/análise , Óxidos de Nitrogênio
15.
Sci Total Environ ; 796: 148975, 2021 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-34271393

RESUMO

Adaptive multi-paddock (AMP) grazing, a grazing system in which individual paddocks are grazed for a short duration at a high stock density and followed by a long rest period, is claimed to be an effective tool to sustainably manage and improve grasslands and enhance their ecosystem services. However, whether AMP grazing is superior to conventional grazing (n-AMP) in reducing soil greenhouse gas (GHG) emissions is unclear. Here, we measured CO2, CH4, and N2O fluxes between August 2017 and August 2019 in 12 pairs of AMP vs. n-AMP ranches distributed across an agro-climatic gradient in Alberta, Canada. We found that field GHG fluxes did not differ between AMP and n-AMP grazing systems, but instead were regulated by specific management attributes, environmental conditions, and soil properties, including cattle stocking rate, cultivation history, soil moisture content, and soil bulk density. Specifically, we found that seasonal mean CO2 emissions increased with increasing cattle stocking rates, while CH4 uptake was lower in grasslands with a history of cultivation. Seasonal mean CO2 emissions increased while CH4 uptake decreased with increasing soil moisture content. In addition, CH4 uptake decreased with increasing soil bulk density. Observed N2O emissions were poorly predicted by the management, environmental conditions, and soil properties investigated in our study. We conclude that AMP grazing does not have an advantage over n-AMP grazing in reducing GHG fluxes from grasslands. Future efforts to develop optimal management strategies (e.g., the use of sustainable stocking rates and avoided cultivation) that reduce GHG emissions should also consider the environmental conditions and soil properties unique to every grassland ecosystem.


Assuntos
Gases de Efeito Estufa , Alberta , Animais , Dióxido de Carbono/análise , Bovinos , Ecossistema , Pradaria , Gases de Efeito Estufa/análise , Metano/análise , Óxido Nitroso/análise , Solo
16.
Chemosphere ; 283: 131176, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34144290

RESUMO

Biochar is a promising novel material for managing phosphorus (P), a nutrient often limiting for primary production but can also be a pollutant, in the environment. Reducing P input to the environment and finding cost-effective approaches to remediate P contamination are major challenges in P management. There is currently no review that systematically summarizes biochar effects on soil P availability and its P removal potential from water systems. In this paper, we comprehensively reviewed biochar effects on soil P availability and P removal from water systems and discussed the mechanisms involved. Biochar affects soil P cycling by altering P chemical forms, changing soil P sorption and desorption capacities, and influencing microbial population size, enzyme activities, mycorrhizal associations and microbial production of metal-chelating organic acids. The porous structure, high specific surface area, and metal oxide and surface functional groups make biochars effective materials for removing P from eutrophic water via ligand exchange, cation bridge, and P precipitation. Because soil and biochar properties are widely variable, the effect of biochar on the fate of P in soil and water systems is inconsistent among different studies. Knowledge gaps in the economic practicability of large-scale biochar application, the longevity of biochar benefits, and the potential ecological risks of biochar application should be addressed in future research.


Assuntos
Poluentes do Solo , Solo , Carvão Vegetal , Fósforo , Água
17.
J Environ Manage ; 295: 113080, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34186312

RESUMO

Unprecedented increases in agricultural nitrous oxide (N2O) emissions in recent years have caused substantial environmental pollution that leads to ozone depletion and global warming. Application of biochar and/or nitrification inhibitors (NIs) has the potential to reduce N2O emissions; however, it is not clear how biochar application may affect the efficacy of NI in reducing nitrification rates, soil enzyme activities, and N2O emissions under different soil moisture regimes. We conducted a 60-day laboratory incubation experiment to study the effects of manure biochar and nitrapyrin (as a NI) on N2O emissions from a urea fertilized soil with either 60 (low) or 80% (high) water-filled pore space (WFPS). Nitrification rates were significantly affected by biochar × NI × WFPS and biochar × WFPS interactions. Biochar initially increased and then decreased the rates, resulting in 45.2 and 26.6% (P < 0.001 for both) overall reductions in low and high WFPS, respectively while NI reduced the rates only in the first 10 days at 60% WFPS. Biochar decreased (P < 0.001) and NI increased (P = 0.007) ß-1,4-N-acetyl glucosaminidase activities while urease activities were increased (P < 0.001) by biochar across WFPS. Biochar had significant interaction with NI in cumulative N2O emissions with the efficacy of NI being reduced when co-applied with biochar. Cumulative N2O emissions were greater at high than at low WFPS; the emissions were decreased by biochar at 60% WFPS and NI at both 60 and 80% WFPS. We conclude that biochar reduces efficacy of nitrapyrin in mitigating N2O emissions and their effects on net nitrification rates, enzyme activities and N2O emissions are dependent on soil moisture level.


Assuntos
Nitrificação , Óxido Nitroso , Agricultura , Carvão Vegetal , Fertilizantes/análise , Óxido Nitroso/análise , Picolinas , Solo
19.
J Hazard Mater ; 419: 126421, 2021 10 05.
Artigo em Inglês | MEDLINE | ID: mdl-34171670

RESUMO

Nickel (Ni) is a potentially toxic element that contaminates soil and water, threatens food and water security, and hinders sustainable development globally. Biochar has emerged as a promising novel material for remediating Ni-contaminated environments. However, the potential for pristine and functionalized biochars to immobilize/adsorb Ni in soil and water, and the mechanisms involved have not been systematically reviewed. Here, we critically review the different dimensions of Ni contamination and remediation in soil and water, including its occurrence and biogeochemical behavior under different environmental conditions and ecotoxicological hazards, and its remediation using biochar. Biochar is effective in immobilizing Ni in soil and water via ion exchange, electrostatic attraction, surface complexation, (co)precipitation, physical adsorption, and reduction due to the biogeochemistry of Ni and the interaction of Ni with surface functional groups and organic/inorganic compounds contained in biochar. The efficiency for Ni removal is consistently greater with functionalized than pristine biochars. Physical (e.g., ball milling) and chemical (e.g., alkali/acidic treatment) activation achieve higher surface area, porosity, and active surface groups on biochar that enhance Ni immobilization. This review highlights possible risks and challenges of biochar application in Ni remediation, suggests future research directions, and discusses implications for environmental agencies and decision-makers.


Assuntos
Recuperação e Remediação Ambiental , Poluentes do Solo , Carvão Vegetal , Níquel , Solo , Poluentes do Solo/análise , Água
20.
Environ Int ; 156: 106638, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34030072

RESUMO

The effect and mechanistic evidence of biochar on the (im)mobilization of potentially toxic elements (PTEs) in multi-contaminated soils, with respect to the role of surface-functional groups and organic/inorganic compounds of biochar, are poorly understood. Herein, biochars produced from grass residues, rice straw, and wood were applied to a mining-soil contaminated with As, Cd, Pb, and Zn for 473-d. Biochars did not reduce the mobilization of Cd and Zn, whereas they simultaneously exhibited disparate effects on As and Pb mobilization. The phenolic hydroxyl and carboxylic groups on the wood biochar's surfaces promoted the conversion of Pb2+ into PbCO3/Pb(OH)2 and/or PbO, minimally by the rice and grass biochars. Rice and grass biochars led to the dissolution of scorodite and the formation of less stable forms of Fe-oxide-bound As (i.e., goethite and ferrihydrite); furthermore, it resulted in the reduction of As(V) to As(III). The PTEs mobilization and phytoavailability was mainly governed by the release of dissolved aliphatic- and aromatic-carbon, chloride, sulfur chemistry, phosphate competition, and the electrostatic repulsion in biochar-treated soils. In conclusion, pristine-biochar has a limited impact on the remediation of multi-contaminated soils, and the use of modified-biochar, possessing higher surface areas and functionality and active exchange sites, are preferred under such conditions.


Assuntos
Arsênio , Poluentes do Solo , Cádmio/análise , Carvão Vegetal , Chumbo , Solo , Poluentes do Solo/análise , Zinco/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...