13841. 题目: Heavy metal leachability in soil amended with zeolite- or biochar-modified contaminated sediment
期刊: Environmental Monitoring and Assessment
作者: Zhilong Peng, Jia Wen, Yunguo Liu, Guangming Zeng, Yuanjie Yi, Ying Fang, Siyu Zhang, Jiaqin Deng, Xiaoxi Cai
摘要: In this work, reuse probability of heavy metal-contaminated sediment for land application was discussed using a 100-day column leaching assessment under the situation of simulated acid rain. For comparison, NaCl-modified zeolite and biochar were firstly studied for their adsorption capacity for Cu, Cd, and Pb in aqueous solution, and then their stabilizing effects on the three metals in sediment-soil mixture. Characteristic results indicated that NaCl-modified zeolite had properties more conducive to metal adsorption than biochar, including higher BET surface area and more negative surface charges. Adsorption capacities of NaCl-modified zeolite fitted by Langmuir isotherm model were 24.83, 35.57, and 133.16 mg g−1 for Cu, Cd, and Pb, respectively. Leaching results demonstrated that metal concentrations in the leachates of soil receiving zeolite- or biochar-modified sediment reduced significantly after 100 days compared with that of soil receiving bare sediment. Moreover, the NaCl-modified zeolite presented a better performance in stabilizing the three metals than biochar from the BCR sequential extraction result. Therefore, stabilization of the dredged contaminated sediment by modified zeolite ensures an environmentally friendly reuse of the sediment on land and makes the sediment treatment operation-able and cost-effective.
13842. 题目: Application of a Novel Coarse-Grained Soil Organic Matter Model in the Environment
期刊: Environmental Science & Technology
作者: Hongru Feng, Haiyan Zhang, Huiming Cao, Yuzhen Sun, Aiqian Zhang, Jianjie Fu
摘要: Soil organic matter (SOM) is ubiquitous in the environment. Intensive efforts have been made to find effective ways to assess the interaction of SOM with contaminants since such interactions are one of the important criteria used to evaluate the migration, persistency and bioavailability of chemicals in the environment. This study aims to extend the application of coarse-grained (CG) dissipative particle dynamics (DPD) to the water/SOM system and predict contaminant mobility in the system. The CG model was based on the Vienna Soil-Organic-Matter Modeler, which can generate flexible condensed-phase models of SOM. A series of DPD simulations was performed to investigate the mobility of perfluorinated sulfonic acids (PFSAs) and hexachlorobutadiene (HCBD). The results indicated that the mobility of PFSAs decreased with increasing length in the carbon chain. In addition, HCBD and hexachlorobenzene (HCB) have similar diffusion coefficients, indicating analogous behavior in SOM. Moreover, water-containing SOM layers may reflect a more realistic situation. This work, coupling the CG method with DPD simulation, provides a new high-efficiency tool to assess the behavior of contaminants in the environment.
13843. 题目: Enhanced removal of organic matter and typical disinfection byproduct precursors in combined iron–carbon micro electrolysis-UBAF process for drinking water pre-treatment
期刊: Journal of Environmental Sciences
作者: Yinghan Chen, Tao Lin, Wei Chen
摘要: The organic matter and two types of disinfection byproduct (DBP) precursors in micro-polluted source water were removed using an iron–carbon micro-electrolysis (ICME) combined with up-flow biological aerated filter (UBAF) process. Two pilot-scale experiments (ICME-UBAF and UBAF alone) were used to investigate the effect of the ICME system on the removal of organic matter and DBP precursors. The results showed that ICME pretreatment removed 15.6% of dissolved organic matter (DOM) and significantly improved the removal rate in the subsequent UBAF process. The ICME system removed 31% of trichloromethane (TCM) precursors and 20% of dichloroacetonitrile (DCAN) precursors. The results of measurements of the molecular weight distribution and hydrophilic fractions of DOM and DBP precursors showed that ICME pretreatment played a key role in breaking large-molecular-weight organic matter into low-molecular-weight components, and the hydrophobic fraction into hydrophilic compounds, which was favorable for subsequent biodegradation by UBAF. Three-dimensional fluorescence spectroscopy (3D-EEM) further indicated that the ICME system improved the removal of TCM and DCAN precursors. The biomass analysis indicated the presence of a larger and more diverse microbial community in the ICME-UBAF system than for the UBAF alone. The high-throughput sequencing results revealed that domination of the genera Sphingomonas, Brevundimonas and Sphingorhabdus contributed to the better removal of organic matter and two types of DBP precursors. Also, Nitrosomonas and Pseudomonas were beneficial for ammonia removal.
13844. 题目: Extracellular polymeric substances of biofilms: suffering from an identity crisis
期刊: Water Research
作者: Thomas Seviour, Nicolas Derlon, Morten Simonsen Dueholm, Hans-Curt Flemming, Elisabeth Girbal-Neuhauser, Harald Horn, Staffan Kjelleberg, Mark C.M. van Loosdrecht, Tommaso Lotti, M, Francesca Malpei, Robert Nerenberg, Thomas R. Neu, Etienne Paul, Hanqing Yu, Yuemei Lin
摘要: Microbial biofilms can be both cause and cure to a range of emerging societal problems including antimicrobial tolerance, water sanitation, water scarcity and pollution. The identities of extracellular polymeric substances (EPS) responsible for the establishment and function of biofilms are poorly understood. The lack of information on the chemical and physical identities of EPS limits the potential to rationally engineer biofilm processes, and impedes progress within the water and wastewater sector towards a circular economy and resource recovery. Here, a multidisciplinary roadmap for addressing this EPS identity crisis is proposed. This involves improved EPS extraction and characterization methodologies, cross-referencing between model biofilms and full-scale biofilm systems, and functional description of isolated EPS with in situ techniques (e.g. microscopy) coupled with genomics, proteomics and glycomics. The current extraction and spectrophotometric characterization methods, often based on the principle not to compromise the integrity of the microbial cells, should be critically assessed, and more comprehensive methods for recovery and characterization of EPS need to be developed.
13845. 题目: Sorption removal of phthalate esters and bisphenols to biofilms from urban river: From macroscopic to microcosmic investigation
期刊: Water Research
作者: Longfei Wang, Yi Li, Peisheng Zhang, Shujuan Zhang, Peng Li, Peifang Wang, Chao Wang
摘要: River biofilms play fundamental roles in shaping the architecture of aquatic systems. Sorption to biofilms was thought to be a crucial mechanism controlling the fate and transport of trace emerging contaminants. This study focused on the role of in situ colonized river biofilms in the early fate of phthalate esters (PAEs) and bisphenols (BPs) at trace concentrations in a representative urban river. PAEs and BPs were readily sorbed to biofilms with uptakes of 38.2 to 162.5 μg/g for PAEs and 1787.7 to 4425.6 μg/g for BPs, respectively. The total mass and characteristics of the colonized biofilms varied in response to seasons and water qualities. The biofilm colonized in the downstream of a wastewater treatment plant exhibited the highest sorption capacity among the tested sites, possibly attributed to the higher organic contents of biofilms owing to the elevated availability of nutrients. Correlation analysis indicates that certain water qualities, e.g., TN and NH3-N, and biofilm properties, e.g., organic and polysaccharide fractions could be selected to predict the sorption capacities of river biofilms. Hydrophobic partitioning into organic matter appears to be the dominant sorption mechanism and biofilm polysaccharides were probably responsible for the adhesion of tested compounds. The contaminant partitioning into biofilm and sediment at mass/volume ratios typical for small rivers suggests that the biofilm could serve as an important sorbing matrix for the trace organic contaminants as compared to the sediments. Our work yields new insights into the early uptake and accumulation of trace plasticizers by natural biofilms, which is of significance in understanding the subsequent transport of trace organic contaminants in fluvial systems.
13846. 题目: Study on the influence of surface potential on the nitrate adsorption capacity of metal modified biochar
期刊: Environmental Science and Pollution Research
作者: Li Long, Yingwen Xue, Xiaolan Hu, Ying Zhu
摘要: Carbon materials, as effective adsorbents to numerous aqueous cationic contaminants, have been hardly applied to remove anions in wastewater. In this work, different modifying agents were used to modify corncob biochars (CC) and the surface potentials of these modified biochars were determined. Based on the findings, modification principle was determined to reveal the relationship between surface potentials of the biochars and their nitrate adsorption capacities. The surface potential was dominated by the metal cations and multivalent cations led to even positive zeta potential. The formation of metal oxide not only led to the augment in surface area but also increase the surface charge. FeCl3-modified biochar (Fe-CC) with the highest positive surface charge was utilized to remove anions (nitrate) from aqueous solutions. Characterization results confirm that Fe2O3 structure were successfully formed on biochar surface. This led to the formation of iron nitrate hydrate (Fe(NO3)3·9H2O), which enabled higher nitrate adsorption performance than that of pristine biochar. Batch experiments showed that nitrate adsorption on the Fe-CC was stable and almost independent of experimental pH and temperature. Based on the Langmuir model results, the maximum nitrate adsorption capacity of Fe-CC was 32.33 mg/g. Coexisting anions had negative influence on the adsorption performance. Findings of this work suggest that the modified biochar can be used in wastewater treatment to remove anions such as nitrate. ᅟ
13847. 题目: Effects of pyrolysis temperature on the physicochemical properties of alfalfa-derived biochar for the adsorption of bisphenol A and sulfamethoxazole in water
作者: Yong-Keun Choi, Eunsung Kan
摘要: The present study reports alfalfa (one of most abundant hays in U.S)-derived biochar for effective removal of emerging contaminants in water for the first time. The physicochemical properties of alfalfa-derived biochar (AF-BC) made at various pyrolysis temperatures were investigated, and correlated with the adsorption of bisphenol A (BPA) and sulfamethoxazole (SMX) in water. The increase in pyrolysis temperatures from 350 °C to 650 °C for the pyrolysis of AF led to a drastic increase in surface area and carbonization with the loss of functional groups. The AF-derived biochar made at 650 °C showed much higher adsorption capacities for BPA and SMX than those made at 350–550 °C, mainly owing to the hydrophobic and π-π interactions supported by its high surface area and degree of carbonization. The adsorption isotherms fitted the Freundlich for BPA and Temkin models for SMX well, respectively. The adsorption capacities of AF 650 for BPA and SMX were higher than those of other biochars but lower than those of commercial activated carbon. The pH-dependent desorption for AF 650 showed high efficiency for SMX, but low efficiency for BPA indicating needs for alternative regeneration methods for BPA.
13848. 题目: Developments in biochar application for pesticide remediation: Current knowledge and future research directions
期刊: Journal of Environmental Management
作者: Sunita Varjani, Gopalakrishnan Kumar, Eldon R. Rene
摘要: The indiscriminate use of pesticides due to modern agricultural practices has received special attention from the scientific community to address the persistence, recalcitrance and multi-faceted toxicity of several pesticides. Pesticides are hazardous/toxic and can accumulate easily into non-target organisms including humans and other life forms. Several studies have been performed to investigate the effect of biochar addition for pesticide remediation. This review provides a comprehensive information on biochar amendment for the remediation of persistent organic pollutants such as pesticides. The types of pesticides and their hazards to life forms are briefly introduced before detailing biochar production, its characteristics and applications. Biochar addition in pesticide polluted environment offers the following advantages: (a) increases the soil water holding capacity, (b) improves aeration conditions in soil, and (c) provides habitat for the growth of microorganisms, thereby facilitating microbial community for metabolic activities and pesticide degradation. This paper also provides an up-to-date review on remediation of pesticides using biochar, the knowledge gaps and the future research directions in this field to evaluate the effect of biochar addition on agricultural and environmental performances.
13849. 题目: Biochar fails to enhance nutrient removal in woodchip bioreactor columns following saturation
期刊: Journal of Environmental Management
作者: Brady S.L. Coleman, Zachary M. Easton, Emily M. Bock
摘要: Denitrifying bioreactors are edge-of-field structures that remove excess nitrogen (N) from intercepted agricultural drainage by supporting the activity of denitrifying microorganisms with a saturated organic carbon substrate. Although these bioreactors successfully mitigate N export, the typical woodchip systems have little effect on phosphorus (P), which is also often present in environmentally harmful quantities in drainage waters. Currently, the evidence that amending woodchip bioreactors with biochar enhances both N and P removal rates is mixed, but more work is required to test this hypothesis under controlled conditions. To determine the effect of biochar amendment on nitrate (NO3-N) and phosphate (PO4-P) removal in woodchip bioreactors, three media types—aged woodchips (W), 10% (B10) and 30% (B30) biochar by volume—were tested under different operational conditions during five-day laboratory trials with horizontal, flow-through columns. Nutrient removal was observed under different flow rates yielding hydraulic residence times of 3, 6, and 12 hours with four formulations of simulated agricultural drainage, all combination of 16.1 or 4.5 mg L−1 NO3-N and 1.9 or 0.6 mg L−1 PO4-P. Each unique treatment with respect to media type, HRT, and influent formulation was tested in triplicate using independent columns. All treatments successfully removed NO3-N, but PO4-P removal was inconsistent. Cumulative NO3-N removal efficiencies ranged 15–98% with an average removal rate of 11.0 g m−3 d−1; biochar amendment enhanced removal only in response to sufficiently high loading rates. Cumulative PO4-P removal efficiencies ranged from 66% removal to 170% export of the influent load; biochar addition was associated with increased export. These results indicate that pine-feedstock biochar poses a substantial increase to PO4-P leaching risk and only modestly enhances NO3-N removal given sufficiently high loading.
13850. 题目: Uncertainties in thermal-optical measurements of black carbon: Insights from source and ambient samples
期刊: Science of The Total Environment
作者: Jiu-meng Liu, Zhen-yu Du, Lin-lin Liang, Qin-qin Yu, Guo-feng Shen, Yong-liang Ma, Mei Zheng, Yuan Cheng, Ke-bin He
摘要: Black carbon (BC) is important due to its complex influences on the environment and on climate in particular. However, reported BC data are largely dependent on measurement techniques due to the multitude of measurement principles. Here we focused on thermal-optical method which has been widely used to determine BC mass (as elemental carbon, EC). Several factors influencing EC measurement were investigated. Results from source samples representing vehicle engine emissions pointed to a continuum of EC components in thermal stability and provided direct observational evidence for the premature evolution of EC in inert atmosphere. It was also found that EC masses may be substantially underestimated for the vehicle exhaust samples if the adopted protocol requires an oxidizing atmosphere to define the split point between organic carbon (OC) and EC. Results from a field campaign conducted during winter in Beijing showed that the optical attenuation (ATN; i.e., the filter transmittance signal, I) was largely saturated for the samples with relatively high loadings, indicating their EC results were unreliable. Improved measurement of EC was achieved by extracting these heavily loaded filters using methanol, given that ATN was considerably reduced by the extraction and, moreover, saturation of ATN (or I) became not evident for the extracted samples. The methanol extraction also significantly reduced the transformation of OC to char-OC, by removing the majority (i.e., ~85%) of the deposited organic aerosols. Higher EC were measured for the extracted samples compared with the untreated ones, indicating that EC tends to be underestimated due to the charring-induced uncertainties. In addition, the methanol extraction largely reduced the inter-protocol discrepancy in the EC measurement results. Similar effects of methanol extraction have been observed during summer in Beijing, despite the seasonal variations of aerosol sources and compositions. This study indicates the potential benefits of methanol extraction for EC measurement.
13851. 题目: A pilot study on using biochars as sustainable amendments to inhibit rice uptake of Hg from a historically polluted soil in a Karst region of China
期刊: Ecotoxicology and Environmental Safety
作者: Ying Xing, Jianxu Wang, Jicheng Xia, Zhenmei Liu, Yonghang Zhang, Ying Du, Wanli Wei
摘要: We studied the addition of two biochars (rice shell biochar (RSB) and wheat straw biochar (WSB)) to soil at doses of 24–72 t/ha on the dynamics of pH, dissolved organic carbon (DOC), sulfate, Fe(III), and Fe(II), as well as on mercury (Hg) mobility in the pore water of a polluted paddy soil, throughout the rice-growing season. The effect of biochar addition to soil on rice biomass and Hg accumulation was also investigated. The key results showed that the addition of RSB or WSB to soil improved significantly the biomass of aboveground tissues of rice plants, particularly at higher dose treatments, compared with the control. The RSB treatment noticeably decreased Hg concentration in the pore water compared to the control, throughout the rice-growing season, and this decrease was likely due to the decreased Hg mobility by the RSB by promoting the level of sulfate in the pore water, which might be reduced to sulfide to combine with Hg to form Hg sulfides. The extent of Hg concentration reduction in the pore water was less pronounced in the WSB treatments relative to the RSB treatments. Addition of RSB to soil at doses of 24–72 t/ha decreased significantly Hg contents in the stalk, bran, hull and polish rice of rice plants compared to the non-treated rice (control), particularly Hg content in the polished rice was below the Chinese safety level (< 20 ng g−1, GB2762-2012). The WSB treatments showed limited effects on rice tissues Hg. Biochar (RSB) may offer a promising method for managing the risk of Hg in paddy field by inhibiting rice Hg uptake.
13852. 题目: High temperature-produced biochar can be efficient in nitrate loss prevention and carbon sequestration
作者: Niguss Solomon Hailegnaw, Filip Mercl, Kateřina Pračke, Jiřina Száková, Pavel Tlustoš
摘要: The effects of biochar on soil properties including nutrients have been reported in previous studies, but few studies targeted on soil nitrogen. Moreover, there remains a lack of studies considering the liberation of ammonia during the ammonium (N-NH4+) adsorption process. Our study aimed to fill this research gap. A pot incubation experiment was conducted for 84 days, with ten different soils and four rates of wood chip-based biochar (0.5, 2, 4, and 8%). Biochar's effect on soil ammonium was inconsistent and insignificant in most of the incubated soils at all biochar rates. This finding contradicted our Langmuir model, which estimated maximum ammonium adsorption capacity of biochar as 6.66 mg of N-NH4+ per g of biochar. Soil response in nitrate (N-NO3−) and dissolved organic carbon (DOC) followed a similar declining trend in all soils in both incubation periods, with the effect boosted according to the biochar application rate. The Langmuir isotherm estimated the maximum N-NO3− adsorption capacity of our biochar as 11.3 mg g−1. Soil original properties determined amount of nitrate and DOC reduction after biochar addition. Our result also indicated poor estimation of ammonium adsorption by biochar due to the liberation of ammonia. As a result, we strongly recommend that ammonia liberation should be considered during adsorption experiments and more studies in this field.
13853. 题目: Microbial-accessibility-dependent electron shuttling of in situ solid-phase organic matter in soils
作者: Wenbing Tan, Beidou Xi, Guoan Wang, Xiaosong He, Rutai Gao, Jie Jiang, Biao Zhu
摘要: The associations between electron shuttling of in situ organic matter and its microbial accessibility in natural soils remain elusive. In this study, through combining soil physical fractionation with incubation experiments, we show that the in situ solid-phase organic matter in soils is a heterogeneous pool with varied electron shuttling capacities due to the diverse soil organic matter protection mechanisms against microbial accessibility. The microbial accessibility of in situ solid-phase organic matter in soils largely acts as a crucial factor in determing the number of redox-active functional groups involved in shuttling electrons from microorganisms to Fe(III) oxides, and therefore the relationship between electron shuttling capacity of in situ solid-phase organic matter and its intrinsic chemical structures.
13854. 题目: Formation of planktonic chromophoric dissolved organic matter in the ocean
期刊: Marine Chemistry
作者: Christopher L. Osburn, Joanna D. Kinsey, Thomas S. Bianchi, Michael R. Shields
摘要: Chromophoric dissolved organic matter (CDOM) is an important fraction of the marine carbon cycle that controls most light absorption and many photochemical and biological processes in the ocean. Despite its importance, the chemical basis for the formation of oceanic CDOM remains unclear. Currently, CDOM's optical properties are best-described by an electronic interaction (EI) model of charge transfer (CT) complexes which form between electron-rich donors and electron-poor acceptors. While terrigenous compounds such as lignin best fit this model, planktonic sources of CDOM have not yet been tested. Here, we have tested CDOM formed during an incubation experiment using a natural phytoplankton assemblage and throughout active growth, stationary phase and algal biomass decomposition. Absorbance of the derived planktonic CDOM generally decreased with increasing wavelength, similar to the reference Pony Lake (PLFA) and Suwanee River (SRFA) fulvic acid solutions used as models of terrigenous CDOM. Further, after 60 days of microbial degradation in the dark, CDOM exhibited fluorescence emission maxima continuously red-shifted into the visible band, consistent with PLFA and SRFA. Reduction of carbonyl-containing groups, key to CT complex formation, with sodium borohydride (NaBH4) produced coherent results in planktonic CDOM and reference FAs. Absorption at 350 nm decreased by 50% for planktonic CDOM and by 30% for PLFA and SRFA, with corresponding increases in spectral slope (S) values, indicating preferential loss of absorption well into the visible. Fluorescence likewise responded with enhanced emission at shorter wavelengths. Apparent quantum yields (Φ) were similarly affected. Results from our work support prior observations that phytoplankton and bacteria are important sources of CDOM that color the ocean's “twilight zone”. We hypothesize that microbial processing of a variety of source substrates into more complex compounds represented as planktonic CDOM likely represents a semi-refractory pool of DOM in the ocean.
13855. 题目: Ultrafiltration membrane fouling performance by mixtures with micromolecular and macromolecular organics
期刊: Environmental Science: Water Research & Technology
作者: Kuo Gao, Tian Li, Junxia Liu, Binzhi Dong, Huaqiang Chu
摘要: Ultrafiltration membrane fouling caused by mixtures of micromolecules (humic acid, HA) and macromolecules (sodium alginate, SA) was studied in a comprehensive manner. The fouling behavior can be divided into two apparent parts according to the HA/SA composition. One part with lower SA composition behaved similarly with HA alone, with the fouling mechanism determined by the standard pore blocking and intermediate pore blocking. While the other part with higher SA composition behaved similarly with SA alone, with the fouling mechanism dominated by the cake filtration. Through the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) approach, the calculation of the interaction energy showed a significant negative correlation between the total interaction energy and the normalized fouling resistance. Conformably, the results showed that HA/SA mixture with the dissolved organic carbon mass ratio of 1:1 which has the lowest interaction energy barrier exhibited the most severe flux decline.
13856. 题目: Managing for soil carbon sequestration: Let’s get realistic
期刊: Global Change Biology
作者: William H. Schlesinger, Ronald Amundson
摘要: Improved soil management is increasingly pursued to ensure food security for the world's rising global population, with the ancillary benefit of storing carbon in soils to lower the threat of climate change. While all increments to soil organic matter are laudable, we suggest caution in ascribing large, potential climate change mitigation to enhanced soil management. We find that the most promising techniques, including applications of biochar and enhanced silicate weathering, collectively are not likely to balance more than 5% of annual emissions of CO2 from fossil fuel combustion.
13857. 题目: Impact of biochar coated with magnesium (hydr)oxide on phosphorus leaching from organic and mineral soils
期刊: Journal of Soils and Sediments
作者: Matthew Riddle, Lars Bergström, Frank Schmieder, Daniel Lundberg, Leo Condron, Harald Cederlund
摘要: Purpose: Recent research suggests that Swedish organic arable soils have been under-recognized as a potential source of phosphorus (P) loading to water bodies. The aim of this study was to compare P losses through leaching from organic and high-fertility mineral soils. In addition, the effectiveness of a magnesium-salt-coated biochar applied below the topsoil as a mitigation strategy for reducing P losses was evaluated. Materials and methods: Phosphorus leaching was measured from four medium- to high-P arable soils, two Typic Haplosaprists (organic 1 and 2), a Typic Hapludalf (sand), and an unclassified loam textured soil (loam), in a 17-month field study utilizing 90-cm-long lysimeters. A magnesium-salt-coated biochar was produced and characterized using X-ray powder diffraction (XPD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and X-ray adsorption (XANES) spectroscopy, and its phosphate adsorption capacity was determined at laboratory scale. It was also applied as a 3-cm layer, 27 cm below the soil surface of the same lysimeters and examined as a mitigation measure to reduce P leaching. Results and discussion: Total-P loads from the 17-month, unamended lysimeters were in the order of organic 2 (1.2 kg ha−1) > organic 1 (1.0 kg ha−1) > sand (0.3 kg ha−1) > loam (0.2 kg ha−1). Macropore flow, humic matter competition for sorption sites, and fewer sorption sites likely caused higher P losses from the organic soils. Analysis by XRD and SEM revealed magnesium was primarily deposited as periclase (MgO) on the biochar surface but hydrated to brucite (Mg(OH)2) in water. The Langmuir maximum adsorption capacity (Qmax) of the coated biochar was 65.4 mg P g−1. Lysimeters produced mixed results, with a 74% (P < 0.05), 51% (NS), and 30% (NS) reduction in phosphate-P from the organic 1, organic 2, and sand, respectively, while P leaching increased by 230% (NS) from the loam. Conclusions: The findings of this study indicate that P leached from organic arable soils can be greater than from mineral soils, and therefore, these organic soils require further investigation into reducing their P losses. Metal-enriched biochar, applied as an adsorptive layer below the topsoil, has the potential to reduce P losses from medium- to high-P organic soils but appear to be less useful in mineral soils.
13858. 题目: Biomass waste components significantly influence the removal of Cr(VI) using magnetic biochar derived from four types of feedstocks and steel pickling waste liquor
期刊: Chemical Engineering Journal
作者: Yunqiang Yi, Guoquan Tu, Dongye Zhao, Pokeung Eric Tsang, Zhanqiang Fang
摘要: Few studies have focused on the effects of biomass feedstocks on the structure-reactivity of magnetic biochar. In this study, four types of magnetic biochar were first prepared using steel pickling waste liquor (serving as iron salt) and sugarcane bagasse (SMBC), rice straw (RMBC), peanut shells (PMBC) and herb residue (HMBC). According to the Langmuir model, the maximum adsorption capacity of Cr(VI) by SMBC was 43.122 mg/g, which was approximately 1.298 times, 3.175 times and 3.677 times higher than that of RMBC, PMBC and HMBC, respectively. The mass balance of chromium indicated that Cr(VI) was removed mainly via reduction. However, the reduction capacity of Cr(VI) differed among the four types of magnetic biochar. The results of characterisations of those magnetic composites before and after reaction demonstrated that the Cr(VI) was electrostatically attracted to the surface of the materials. Consequently, most of the adsorbed Cr(VI) was reduced and the remainder of the Cr(VI) was complexed with C=O groups in magnetic biochar. Further, the total iron in magnetic biochar, especially Fe(II), played a dominant role in the removal and reduction of Cr(VI). Finally, correlation analysis showed that the cellulose and ash in the biomass were the main factors that induced the differences in the magnetic biochar’s total iron content. Therefore, this study may provide a reference for the use of magnetic biochar to remove Cr(VI) from aqueous solutions.
13859. 题目: Activation of peroxymonosulfate by graphitized hierarchical porous biochar and MnFe2O4 magnetic nanoarchitecture for organic pollutants degradation: Structure dependence and mechanism
期刊: Chemical Engineering Journal
作者: Haichao Fu, Shuanglong Ma, Peng Zhao, Shengjun Xu, Sihui Zhan
摘要: Three novel graphitized hierarchical porous biochar (MX) and MnFe2O4 magnetic composites (MnFe2O4/MX) have been prepared for degrading organic pollutants by peroxymonosulfate (PMS) activation. MX including MS, ML, MC synthesized using corn stems (S), leaves (L) and cores (C) as raw materials, respectively, possesses hierarchical porous structure, graphitization domains and tremendous surface area. The orange II removal effects of MX and MnFe2O4/MX outperform the corresponding carbonization products, despite that adsorption probably undertakes the major removal efficiency for MX and degradation contributes the most for MnFe2O4/MX. A structure-dependent degradation efficiency is discovered for MX and MnFe2O4/MX, among of which both MS and MnFe2O4/MS present the best removal effect, by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The lowest EIS owning to its better balance between graphitization degree and specific surface area and micropore volume of MnFe2O4/MS among MnFe2O4/MX explains its best catalytic activity. The catalytic degradation occurs by the following three ways. First, the radical-induced oxidation is attained by surface-bound •SO4– and •OH on MnFe2O4 nanoclusters and hierarchical porous carbon nanosheets generated by one-electron reduction of PMS under the participating and coupling of Mn(III)/Mn(II), Fe(III)/Fe(II), O2/•O2-, and active sites on carbon surface. Second, non-radical pathway involves the contribution of 1O2, which is produced in a large quantity by promoted self-decomposition of PMS in presence of MnFe2O4/MS. Third, non-radical pathway is achieved through electron transfer from organic compounds as electron donator to PMS as electron acceptor mediated by graphitization structures. Taking into consideration the excellent degradation performance, easy magnetic separation, and bulk availability of MnFe2O4/MS, this work is expected to pave a new way for precision utilization of corn biomass-based biochar for environmental application.
13860. 题目: Impacts of forests and forestation on hydrological services in the Andes: A systematic review
期刊: Forest Ecology and Management
作者: Vivien Bonnesoeur, Bruno Locatelli, Manuel R. Guariguata, Boris F. Ochoa-Tocachi, Veerle Vanacker, Zhun Mao, Alexia Stokes, Sarah-Lan Mathez-Stiefel
摘要: Several Andean countries have planned to restore forest cover in degraded land to enhance the provision of multiple ecosystem services in response to international commitments such as the Bonn Challenge. Hydrological services, e.g. water supply, hydrological regulation and erosion mitigation, are particularly important to sustain the life of more than fifty million Andean people. While rapid and important forest cover changes have occurred during recent decades, critical information on the impact of forestation on hydrological services has not yet been synthesized in the context of Andean ecosystems. We define forestation as the establishment of forest by plantation or natural regeneration on areas that either had forest in the past or not. To help improve decision-making on forestation in the Andes, we reviewed the available literature concerning the impacts of forestation on water supply, hydrological regulation and mitigation of erosion and landslides. We also examined available data on the most relevant hydrological processes such as infiltration, evapotranspiration and runoff in forest stands. Hydrological services from native forests were also included as a reference state for comparing processes and services provided by forestation. Following systematic review protocols, we synthesized 155 studies using different methods, including meta-analyses and meta-regressions. Results show that forestation has had clear impacts on degraded soils, through reducing water erosion of soils and risk of moderate floods, increasing soil infiltration rate by 8 and topsoil organic matter (SOM). We found that 20 years of tree plantation was sufficient to recover infiltration rate and sediment yield close to the levels of native forests whereas SOM, soil water storage and surface runoff of native forests could not be recovered by forestation in the time scales examined. The benefits in terms of hydrological regulation are at the expense of a reduction in total water supply since forest cover was associated with higher water use in most Andean regions. Forestation with native species was underrepresented in the reviewed studies. The impact of forestation on landslides has also been largely overlooked in the Andes. At high elevations, exotic tree plantations on Andean grasslands (e.g. páramo and puna) had the most detrimental consequences since these grasslands showed an excellent capacity for hydrological regulation and erosion mitigation but also a water yield up to 40% higher than tree plantations. People engaged in forest restoration initiative should be aware that hydrological services may take some time for society and the environment to show clear benefits after forestation.