201. 题目: Examining samarium sorption in biochars and carbon-rich materials for water remediation: Batch vs. continuous-flow methods
作者: Joan Serra-Ventura, Miquel Vidal, Anna Rigol
摘要: Samarium (Sm) sorption from aqueous solutions was evaluated in biochars (derived from castor meal (CM), eucalyptus forest residues (CE), sugarcane bagasse (SB) and green pericarp of coconut (PC)) and in other carbon-rich materials (coal fines (CF); two commercial activated charcoals (GAC, NGAC)) by applying batch and continuous-flow sorption experiments. Batch experiments revealed great Kd values, in the range of 104–105 L kg−1, and high Sm sorption percentages (>97%, except for SB) in the range of environmental representative concentrations, using as-received materials, with no further treatments. Maximum sorption capacities were derived from sorption isotherms using the Langmuir model (from 1.2 to 37 mg g−1). Continuous-flow sorption experiments permitted to obtain maximum sorption capacities by mass balance and by fitting the experimental breakthrough curves to Thomas and Yan models. CF exhibited the greatest maximum sorption capacity (40 mg g−1) besting the commercial activated charcoals, while CM was established as the best biochar (7.2 mg g−1), with similar results to NGAC (12 mg g−1) but worse than GAC (36 mg g−1). The contribution of cation exchange in Sm sorption was confirmed to be significant for most materials based on the analyses of cations leached during continuous-flow sorption experiments. Maximum sorption capacities derived from Langmuir fitting correlated well with maximum sorption capacities obtained from continuous-flow experiments. Both methods were confirmed to be suitable to determine the maximum Sm sorption capacity of the materials and then to propose the most suitable materials that can act as alternative to commercial activated charcoals.
202. 题目: A Critical Review on the Multiple Roles of Manganese in Stabilizing and Destabilizing Soil Organic Matter
期刊: Environmental Science & Technology
作者: Hui Li, Fernanda Santos, Kristen Butler, Elizabeth Herndon
摘要: Manganese (Mn) is a biologically important and redox-active metal that may exert a poorly recognized control on carbon (C) cycling in terrestrial ecosystems. Manganese influences ecosystem C dynamics by mediating biochemical pathways that include photosynthesis, serving as a reactive intermediate in the breakdown of organic molecules, and binding and/or oxidizing organic molecules through organo-mineral associations. However, the potential for Mn to influence ecosystem C storage remains unresolved. Although substantial research has demonstrated the ability of Fe- and Al-oxides to stabilize organic matter, there is a scarcity of similar information regarding Mn-oxides. Furthermore, Mn-mediated reactions regulate important litter decomposition pathways, but these processes are poorly constrained across diverse ecosystems. Here, we discuss the ecological roles of Mn in terrestrial environments and synthesize existing knowledge on the multiple pathways by which biogeochemical Mn and C cycling intersect. We demonstrate that Mn has a high potential to degrade organic molecules through abiotic and microbially mediated oxidation and to stabilize organic molecules, at least temporarily, through organo-mineral associations. We outline research priorities needed to advance understanding of Mn–C interactions, highlighting knowledge gaps that may address key uncertainties in soil C predictions.
203. 题目: Vapor- and Aerosol-Phase Atmospheric Organic Matter in Urban Air of the Midwest USA
期刊: Atmospheric Environment
作者: Rosa M. Flores, Paul V. Doskey
摘要: Vapor- and aerosol-phase atmospheric organic matter were collected in East St. Louis, MO using the high-volume sampling method. Samples were processed by traditional analytical methods and analyzed by multidimensional gas chromatography with time-of-flight mass spectrometric detection. Levels of identified, hydrocarbon-like organic vapor and aerosol species (i.e., HOV and HOA, respectively) were 10-42 ng m-3 and 0.020-3.6 ng m-3, respectively. Concentrations of identified, oxygenated organic vapor and aerosol species (i.e., OOV and OOA, respectively) were 2-66 ng m-3 and 23-310 ng m-3, respectively. The principal feature of the HOV was an unresolved complex mixture that represented 54.5 ± 11.3% of the total HOVs during the field campaign. Levels of n- and branched alkanes, alkyl and cycloalkylbenzenes, polyaromatic hydrocarbons (PAHs), and alkyl-substituted PAHs generally declined from the morning rush hour to the 1000-1400 sampling period, which was similar to the expected trend in reactivity with respect to OH. The OOV included aliphatic mono-carboxylic acids, aliphatic and aromatic alcohols, aldehydes, and ketones, and alicyclic ketones, alcohols, and epoxides (i.e., montoterpenoids). The bulk of the OA species (∼99%) were a complex mixture of OOA, which included multifunctional n-aliphatic, alicyclic, and aromatic hydrocarbons, dicarboxylic and ketocarboxylic aliphatic and dicarboxylic monoaromatic acids, lactones, tetrols, and pentitols. The sampling and analytic techniques provided quantitative molecular information for HOVs in ambient air, which are a missing source of secondary organic aerosol precursors. Molecular characterization and quantitation of HOVs and OOA species will facilitate predictions of SOA formation using molecular-specific models.
204. 题目: Spatial variation of particulate black carbon, and its sources in a large eutrophic urban lake in China
期刊: Science of The Total Environment
作者: Changchun Huang, Lize Meng, Yao He, Nana Shang, Heyu Yu, Tao Huang, A-xing Zhu, Hao Yang, Kan Zhao, Ling Yao
摘要: Black carbon (BC), characterized by high aromaticity and stability, has been recognized as a substantial fraction of the carbon pool in soil and sediment. The effect of BC on the particulate organic carbon (POC) pool in lake water, which is an important medium of carbon transmission and transformation, has not been thoroughly studied. The investigations of BC composition and distribution, POC, polycyclic aromatic hydrocarbons (PAHs), and stable carbon and nitrogen isotopes were conducted in a eutrophic urban lake, Taihu Lake, which is the third largest freshwater lake in China. The results indicate that the BC is composed of 55 ± 12% char and 45 ± 12% soot and accounted for 12 ± 6% of POC (the maximum value is 31%). The comparatively high levels of BC and char are distributed in the northern Taihu Lake, especially in Meiliang Bay (0.72 ± 0.38 mg L-1 and 0.45 ± 0.24 mg L-1). The distribution of soot presents a declining trend from the lakeshore to the central lake, particularly in the northern, western, and southern lakes. Source apportionment results from positive matrix factorization of PAHs suggest that consumption of fossil fuel (79 ± 20%) is the dominant source of BC, which agrees with the low ratio of char/soot (1.41 ± 0.71) and relatively depleted δ13C. The covariation of BC and PAHs and terrestrial dissolved organic carbon indicate that the effect of terrestrial input significantly regulates the distribution of BC in Taihu Lake, which is reflected in the high BC value along the lakeshore.
205. 题目: Elevated temperatures drive abiotic and biotic degradation of organic matter in a peat bog under oxic conditions
期刊: Science of The Total Environment
作者: Roya AminiTabrizi, Katerina Dontsova, Nathalia Graf Grachet, Malak M. Tfaily
摘要: Understanding the effects of elevated temperatures on soil organic matter (SOM) decomposition pathways in northern peatlands is central to predicting their fate under future warming. Peatlands role as carbon (C) sink is dependent on both anoxic conditions and low temperatures that limit SOM decomposition. Previous studies have shown that elevated temperatures due to climate change can disrupt peatland's C balance by enhancing SOM decomposition and increasing CO2 emissions. However, little is known about how SOM decomposition pathways change at higher temperatures. Here, we used an integrated research approach to investigate the mechanisms behind enhanced CO2 emissions and SOM decomposition under elevated temperatures of surface peat soil collected from a raised and Sphagnum dominated mid-continental bog (S1 bog) peatland at the Marcel Experimental Forest in Minnesota, USA, incubated under oxic conditions at three different temperatures (4, 21, and 35 °C). Our results indicated that elevated temperatures could destabilize peatland's C pool via a combination of abiotic and biotic processes. In particular, temperature-driven changes in redox conditions can lead to abiotic destabilization of Fe-organic matter (phenol) complexes, previously an underestimated decomposition pathway in peatlands, leading to increased CO2 production and accumulation of polyphenol-like compounds that could further inhibit extracellular enzyme activities and/or fuel the microbial communities with labile compounds. Further, increased temperatures can alter strategies of microbial communities for nutrient acquisition via changes in the activities of extracellular enzymes by priming SOM decomposition, leading to enhanced CO2 emission from peatlands. Therefore, coupled biotic and abiotic processes need to be incorporated into process-based climate models to predict the fate of SOM under elevated temperatures and to project the likely impacts of environmental change on northern peatlands and CO2 emissions.
206. 题目: Sorption of arsenic by composts and biochars derived from the organic fraction of municipal solid wastes: Kinetic, isotherm and oral bioaccessibility study
期刊: Environmental Research
作者: Jacqueline Zanin Lima, Eduardo Ferreira da Silva, Carla Patinha, Nuno Durães, Eny Maria Vieira, Valéria Guimarães Silvestre Rodrigues
摘要: The historic contamination of water and soils by arsenic (As) is an extremely alarming environmental and public health issue worldwide. This study investigated the relationship between As sorption and physicochemical properties of composts and biochars derived from the organic fraction of municipal solid wastes (OFMSW) towards the development of promising sorbents with value-added solid wastes management solutions. The sorbents were characterized and their effectiveness on the As sorption was tested. Several isothermal and kinetic sorption models were used for the prediction of sorption. Composts did not show promising sorption capacities, and in some cases, the As immobilization was practically null. In contrast, biochars achieved higher sorption performance, and the experimental data fitted well on Dubinin-Rabushkevich and Langmuir models, with higher R2 values. The maximum sorption capacities of BC700 estimated by such models were 6.495 and 170.252 mg g−1, respectively, whereas those of BC500 estimated by D-R and Langmuir models were only 0.066 and 0.070 mg g−1, respectively. In sorption kinetics, As was retained onto biochars at a faster first stage, reaching equilibrium after approximately 1h and 2h for initial concentrations of 10 and 100 mg L−1. The pseudo-second-order, Ritchie's second-order, Ritchie's, and Elovich models more adequately described the sorption kinetics of As onto biochars with high R2 values. Overall, the complexation and precipitation were predominant mechanisms for As sorption by OFMSW-derived biochars. Furthermore, the mathematical models indicated contributions arise from physisorption and external and internal diffusion mechanisms. Although BC700 can immobilize large As amounts, the gastric phase of the oral bioaccessibility test revealed more than 80% of the sorbed As could be released under conditions similar to a human stomach (pH∼1.2). Such conclusions have given important insights about the refining of effective and eco-friendly remediation technologies for the management and rehabilitation of As-contaminated soil and water, particularly in developing countries.
207. 题目: Biochar derived from spent mushroom substrate reduced N2O emissions with lower water content but increased CH4 emissions under flooded condition from fertilized soils in Camellia oleifera plantations
作者: Xintong Xu, Xi Yuan, Qiang Zhang, Qixuan Wei, Xiaojun Liu, Wenping Deng, Jiawei Wang, Wenting Yang, Bangliang Deng, Ling Zhang
摘要: Agricultural soils are major sources of greenhouse gases (GHGs) that related with intensive fertilizer input. Biochar is widely used to mitigate GHGs, which may interact with soil water content impacting GHG emissions. Camellia oleifera fruit shell (FS) and spent mushroom substrate (MS) are ideal biochar feedstocks. However, the impact of water content and biochar on soil GHG emissions has not been thoroughly understood. Here, we examined CH4 and N2O emissions from C. oleifera plantation soils as affected by biochar (derived from MS or FS, 1 g 25 g−1 soil), water content (60%, 120%, 240% or 360% water holding capacity, WHC), and fertilization (control or chicken manure, CM 2.5 g g−1 soil). We determined the abundance of related microbial functional genes to obtain the underlining mechanisms. The results showed that higher N2O emissions occurred in soils with 120%WHC, due to increased abundance of AOA, AOB and nirS. MS or FS biochar differed in their effects on soil GHG emissions with different WHC. Ms biochar was higher in pH, C/N and specific surface area, and mitigated more N2O emissions from soils with CM and 120%WHC relative to FS biochar (by 92.9% and 34.6%, respectively). MS biochar significantly decreased abundance of nitrification related functional genes (AOA, AOB) in soils with 120%WHC and CM, which explained the decrease in N2O emissions. However, MS biochar increased cumulative CH4 emissions from flooded soils via increase in mcrA abundance. Thereby, biochar feedstocks should be considered in CH4 and N2O mitigations from soils with different water contents.
208. 题目: Facial fabricated biocompatible homogeneous biocarriers involving biochar to enhance denitrification performance in an anoxic moving bed biofilm reactor
期刊: Bioresource Technology
作者: Zi Song, Xiaoli Su, Pu Li, Feiyun Sun, Wenyi Dong, Zilong Zhao, Zheng Wen, Runfeng Liao
摘要: Biochar prepared from pineapple peel was facially combined with polyurethane sponges for the first time to form homogeneous biocompatible biocarriers, which can enhance denitrification performance in an anoxic MBBR. The experiments showed that a higher NO3--N removal efficiency (96.24 ± 1.3%) and kinetic constant (0.26 h-1) were obtained in the MBBR employing these new biocarriers (B-MBBR), compared with a control MBBR with polyurethane sponges (C-MBBR). The attached and suspended biomass of the B-MBBR was increased by 47% and 26%, respectively. Biochar significantly enhanced the abundance of functional bacteria in terms of promoting biofilm (i.e., Leptonema), denitrifying bacteria (i.e., Thauera, Enterobacter and Pseudomonas) and electroactive bacteria (i.e., Geobacter) in the B-MBBR. Meanwhile, based on the content of coenzyme I (NADH) and denitrifying enzymes, biochar would also enhance electron transport activity for denitrification. Consequently, these facial prepared biocarriers are effective to enhance denitrification performance in MBBR with application significance.
209. 题目: Differences in Photosensitized Release of VOCs from Illuminated Seawater versus Freshwater Surfaces
期刊: ACS Earth and Space Chemistry
作者: Laura T. Stirchak, Letizia Abis, Carmen Kalalian, Christian George, D. James Donaldson
摘要: Recent studies have shown that photochemical reactions occurring at the air–water interface are a source of volatile organic compounds (VOCs) to the atmosphere. We report here the photosensitized formation of VOCs from illuminated freshwater and seawater mimics containing nonanoic acid (NA) and/or Suwannee River natural organic matter (SRNOM). Under an atmosphere of air, the total blank-corrected steady-state concentration of VOCs formed from illuminated seawater coated with nonanoic acid is somewhat smaller than that formed from freshwater, suggesting some differences in photochemical pathways for the two substrates. The total blank-corrected steady-state concentration of VOCs more than doubles from both freshwater and seawater NA-coated surfaces under nitrogen compared to air. The addition of SRNOM as a photosensitizer induces some photochemistry from the seawater sample under air, but no chemistry is seen with freshwater or under nitrogen for either substrate. Adding SRNOM to the nonanoic acid-containing solutions roughly doubles the total steady-state concentration of VOCs emitted from both freshwater and seawater surfaces under air. The small differences in product formation for the two substrates imply some difference in the photochemical mechanisms operating in freshwater versus seawater, which may be due to the presence of halides and metals as well as pH differences between the two aqueous systems.
210. 题目: Effects of microplastics on humification and fungal community during cow manure composting
期刊: Science of The Total Environment
作者: Yanting Zhou, Yue Sun, Jili Liu, Xiuna Ren, Zengqiang Zhang, Quan Wang
摘要: The effect of microplastics (MPs) on the biological treatment of organic waste has been extensively studied, but little is known about the influence of different MPs on composting humification and the fungal community. In this study, PE, PVC, and PHA MPs were individually mixed with cow dung and sawdust and then composted. The results showed that different MPs had various influences on humification, and the humic acid to fulvic acid ratio of all MP-added treatments (0.44–0.83) was lower than that of the control (0.91). During the composting process, Ascomycota (26.32–89.14%) and Basidiomycota (0.47–4.78%) are the dominant phyla in all treatments and all microplastics decreased the diversity and richness of the fungal community at the thermophilic stage of composting. Exposure to MPs had an obvious effect on the fungal community at the genus level, and the addition of PHA and PE MPs increased the relative abundance of phytopathogenic fungi. LEfSe and network analysis indicated that MPs reduced the number of biomarkers and led to a simpler and more unstable fungal community structure compared to the control. This study has important implications for assessing microplastic pollution and organic waste disposal.
211. 题目: Biochar promotes soil organic carbon sequestration and reduces net global warming potential in apple orchard: A two-year study in the Loess Plateau of China
期刊: Science of The Total Environment
作者: Jiale Han, Afeng Zhang, Yanhong Kang, Jianqiao Han, Yang Bo, Qaiser Hussain, Xudong Wang, Man Zhang, Muhammad Azam Khan
摘要: The Loess Plateau is China's primary apple-growing area, and the orchard is a significant source of greenhouse gases (GHGs) emissions due to high nitrogen fertilizer input. Thus, a two-year field study was carried out to investigate the effects of apple wood derived biochar on GHGs emissions during apple orchard production, including soil organic carbon sequestration (SOCSR) and net global warming potential (NGWP) assessments. There are four treatments in this study: 20 t ha−1 biochar in a non-fertilized plot (B); no biochar in a fertilized plot (F); 20 t ha−1 biochar in a fertilized plot (FB); no biochar in a non-fertilized plot (CK). Results showed that the combined application of biochar and fertilizer stimulated CO2 emissions by 9.25% and 8.39% than either biochar or fertilizer alone. Meanwhile, biochar in fertilized plot increased annual N2O emissions by 32.6% as compared to fertilized plot without biochar amendment. Compared with CK, biochar had no significant effect on GHG emissions in unfertilized plot. The N2O emission factor of FB and F were 0.91% and 0.45% respectively in 2017–2018 and they were both 0.34% in 2018–2019. Moreover, compared with CK, the FB and B treatments increased the SOCSR by 316.52% and 354.78%, while, decreased the NGWP by 368.93% and 480.91%, respectively. Thus, biochar application may help reduce the impact of apple production on climate change by sequestering more soil organic carbon and decreasing the NGWP.
212. 题目: Effects of biochar dosage on treatment performance, enzyme activity and microbial community in aerated constructed wetlands for treating low C/N domestic sewage
期刊: Environmental Technology & Innovation
作者: Yan Zhang, Mengqi Li, Lu Dong, Chunxiao Han, Ming Li, Haiming Wu
摘要: Biochar (BC) has been widely utilized in constructed wetland (CW) for intensifying the removal of pollutants from low carbon/nitrogen (C/N) wastewater. However, there are knowledge gaps about the optimal proportion of BC as an external carbon substrate. This study developed four sets of aerated vertical flow (VF) CWs with different BC amendment proportions (0%, 25%, 50%, 75%) to explore the influence of BC dosage on the treatment performance, enzyme activity and microbial community. The results showed that all CWs achieved better COD (above 90%) and NH4+-N (above 99%) removal due to adequate oxygen supplement, while the best TN removal (67%) was obtained in CW with 50% BC addition. TP removal ascended gradually with the increasing BC amendment proportion. The activity of enzymes and the proportion of Proteobacteria and Patescibacteria at the phylum level were appreciably enhanced with the addition of BC.
213. 题目: Changing soil organic carbon with land use and management practices in a thousand-year cultivation region
期刊: Agriculture, Ecosystems & Environment
作者: Xiaoqian Niu, Chenggong Liu, Xiaoxu Jia, Juntao Zhu
摘要: Soil organic carbon (SOC) is a critical mass of global terrestrial carbon store that can be altered by land use and land management practices. As an important grain production area in the Yellow River basin, there have been intensive agricultural activities in the Guanzhong Plain for over 1000 years. The conversion of cropland into orchard and changes in land management practices could have altered the distribution and amount of SOC stores in the region. To determine spatial variations in SOC and its response to changes in land use and land management practices in the thousand-year cultivated region, SOC content was measured at 127 sites, including 117 sites in the 0–100 cm soil layer and 10 sites in the 0–1000 cm soil layer. The results showed a pronounced decline in SOC content with increasing depth in the upper 100 cm soil layer, whereas it was relatively low and stable in deeper soil layers. SOC stock in the 0–100 and 100–1000 cm soil layers accounted for 16.9% and 83.1%, respectively, of the total SOC stock in the 0–1000 cm soil profile. Compared with the 1980s, mean SOC stock in the 0–100 cm soil layer significantly increased (by 0.69 kg m−2) over the 40-year period. Furthermore, no significant difference was observed in SOC content between cropland and orchard land soils for both the 0–100 and 100–1000 cm soil layers. Land management practices (irrigation and fertilization), climatic variables (precipitation and temperature), and soil properties (pH and clay content) together influenced the spatial variations in SOC in the 0–60 cm soil depth. However, variations were dominantly driven by soil properties at depths below 60 cm. Therefore, while SOC in layers below 100 cm was critical for carbon budget estimations, SOC was not altered by changes in agricultural land use in both the shallow and deep soils of the study area. Agricultural management practices, soil properties, and organic carbon storage in deep soils need to be considered in future carbon budget studies in cultivated lands, especially in regions with deep soils.
214. 题目: Connecting the Age and Reactivity of Organic Carbon to Watershed Geology and Land Use in Tributaries of the Hudson River
期刊: Journal of Geophysical Research: Biogeosciences
作者: Mason Stahl, Jack Wassik, Jaclyn Gehring, Connor Horan, Andrew Wozniak
摘要: We characterized the dissolved organic matter (DOM) under baseflow conditions from a set of rivers in the Mohawk and Hudson River watersheds. The rivers in this study drain a range of bedrock geologies and land cover. We identify how those factors influence riverine DOM reactivity and the source, age, and composition of the biolabile DOM. We performed laboratory incubation experiments to characterize each river's reactive and non-reactive DOM pools. Measurements of dissolved organic carbon concentration, radiocarbon, Ultraviolet-visible spectroscopy absorbance, and Fourier-transform ion cyclotron resonance mass spectrometry (FTICR-MS) analysis were performed at each incubations start and end, allowing us to determine the quantity, age, and composition of the reactive and non-reactive DOM pools. We find that lithology controls bulk DOM ages, with watersheds underlain by shale/limestone having the most aged DOM and crystalline/metasedimentary watersheds having the youngest DOM. We observe that for a given lithology, bulk DOM age increases with the proportion of agricultural land in the watershed – suggesting agricultural practices mobilize aged DOM. FTICR-MS analysis reveals that both lithology and land cover influence DOM composition. Shale/limestone watersheds showed DOM compositions distinct from other watershed lithologies, and the percentage of nitrogen-containing DOM correlated with agricultural influence. In two of the studied rivers we find that the biolabile DOM fraction is older than the bulk DOM (upwards of 7 kyr) revealing that aged DOM may be preferentially consumed in these rivers. Our findings provide insight into how riverine carbon cycles may respond to watershed disturbances that influence DOM inputs to rivers.
215. 题目: Novel K-enriched organomineral fertilizer from sewage sludge-biochar: Chemical, physical and mineralogical characterization
期刊: Waste Management
作者: Jóisman Fachini, Cícero Célio de Figueiredo, Joaquim José Frazão, Sara Dantas Rosa, Juscimar da Silva, Ailton Teixeira do Vale
摘要: Sewage sludge biochar (SSB) is a multi-nutrient fertilizer with very low K concentration. This study presents a novel K-enriched SSB fertilizer with the potential to increase K use efficiency by crops. The object of this work was therefore to evaluate the physical–chemical, morphological and mineralogical characteristics of a SSB organomineral fertilizer (OSSB) enriched with K. SSB was enriched with KCl and K2SO4 using three technological methods (granules, pellets and powders). The enrichment of SSB with K ensured a K2O content about 75 times higher than the pure SSB. Organominerals in powder form had higher levels of total nitrogen, calcium, sulfur, phosphorus and higher pH than granules and pellets. The morphology and physical characteristics of enriched OSSBs were more influenced by the form of the fertilizer than by the source of K. In general, the enriched OSSBs are influenced by the quantities of feedstocks and the enrichment technology.
216. 题目: Biochar amendment rapidly shifts microbial community structure with enhanced thermophilic digestion activity
期刊: Bioresource Technology
作者: Shiva Khoei, Abigail Stokes, Brandon Kieft, Paul Kadota, Steven Hallam, Cigdem Eskicioglu
摘要: Effects of powdered (< 0.075 mm) biochar on thermophilic anaerobic digestion were investigated with biochemical methane potential (BMP) assays. The assays had substrate to inoculum ratios (SIR) of 2.2 and 4.4 g-volatile solids (VS)/g-VS and biochar dosing of 6 g/g-total solids (TS)inoculum. Compared to control, biochar amendment enhanced methane production rates by 94%, 75%, and 20% in assays utilizing substrates of acidified sludge at 70°C, 55°C and non-acidified mixed sludge, respectively. All controls experienced acute inhibition with lag phases from 12 - 52 days at SIR of 4.4 g-VS/g-VS, while assays with biochar generated methane from day 4. Biochar addition resulted in a rapid shift in microbial community structure associated with an increase in Methanothermobacteraeae (hydrogenotrophic) and Methanosarcinaceae archaea, as well as various volatile fatty acid (VFA)-degrading and hydrogen-producing bacteria. Biochar presents great potential to tackle VFA accumulation, abbreviate lag phase and increase methane rate, particularly at high organic loadings.
217. 题目: Competitive adsorption of heavy metals onto modified biochars: Comparison of biochar properties and modification methods
期刊: Journal of Environmental Management
作者: Han-Saem Lee, Hyun-Sang Shin
摘要: Various biochars (BCs) have been developed to remove heavy metals contained in road runoff; however, there is insufficient information regarding the competitive adsorption efficiency of modified BC with regard to heavy metals due to a lack of comparative evaluation based on BC properties and modification methods. In this study, three different types of BC (RBC: rice husk, WBC: wood chip, MBC: mixture) were modified following five different methods: acidic, alkaline, oxidic, and manganese oxide (MnOx) and iron oxide (FeOx) impregnation. The changes in the physicochemical and morphological properties of the modified BC were investigated, and the adsorption characteristics of three heavy metals (Cd, Pb, and Zn) under single and mixed conditions were compared and evaluated. The improvements in the BC properties varied for different BC types and modification methods; in particular, alkaline and manganese modification caused substantial the changes in the surface area and functional groups (such as aromatic ring, –OH, and Mn–O groups). The BC prepared by manganese oxide impregnation absorbed a high amount of heavy metals (>9.15 mg/g) even under mixed conditions through cation exchange and surface complexation. The distribution coefficient (Kd) of heavy metals was high in the order of Pb > Cd > Zn; thus, the adsorption of Pb replaced that of Zn in competitive adsorption due to the difference in their affinity to BC. Therefore, the results suggest that BC prepared by manganese oxide impregnation is suitable for removing heavy metals from road runoff, as it maintained high heavy metals adsorption regardless of the BC material, even under competitive conditions.
218. 题目: A comparative study on the degradation of phenylurea herbicides by UV/persulfate process: Kinetics, mechanisms, energy demand and toxicity evaluation associated with DBPs
期刊: Chemical Engineering Journal
作者: Fan Lai, Fu-Xiang Tian, Bin Xu, Wen-Kai Ye, Yu-Qiong Gao, Chen Chen, Hai-Bo Xing, Bo Wang, Meng-Jiao Xie, Xiao-Jun Hu
摘要: The degradation performance of selected phenylurea herbicides (isoproturon and chlorotoluron) by UV/persulfate (PS) as well as toxicity assessments associated with disinfection by-products (DBPs) in subsequent oxidation were comparatively studied. The elimination of herbicides followed pseudo first-order kinetics well. Then effects of UV intensity, pH, PS dosage and water matrix (background ions and nature organic matter (NOM)) were investigated detailedly. Increased kobs values were observed at higher PS dosages and greater UV intensity, but the degradation was basically resistant to pH variation. kobs could be inhibited by coexistent ions and NOM. Radical scavenging study revealed the more important role of sulfate radical (SR, SO4•−) than hydroxyl radical (HR, HO•). kapp of HO• and SO4•− towards isoproturon and chlortoluron were determined respectively. The results also indicated that the relative reactivity of alkyl- or halogen- substituted phenylurea herbicides with HO• and SO4•− can be correlated with Hammett constants as the molecular descriptor. Then a quantitative structure-activity relationship was established to predict the structure-dependent reactivity of phenylurea herbicides by UV/PS concerning substituent effects. The energy demand of UV/PS system was evaluated. The degradation intermediates by direct UV, UV/H2O2 as well as UV/PS were comparatively identified and the related destruction pathways were postulated. Compared with UV and UV/H2O2, UV/PS was superior in controlling the DBPs generation in post-disinfection of these herbicides. The data supported that SR-advanced oxidation processes (AOPs) had more advantages in removal efficiency and toxicity control than HR-AOPs. This study provided some theoretical bases for the UV/PS degradation behaviors of structurally similar phenylurea herbicides with regard to different substituents on the aromatic ring.
219. 题目: Effect of different polymers of microplastics on soil organic carbon and nitrogen – A mesocosm experiment
期刊: Environmental Research
作者: Fanrong Meng, Xiaomei Yang, Michel Riksen, Violette Geissen
摘要: Agricultural microplastic pollution has become a growing concern. Unfortunately, the impacts of microplastics (MPs) on agricultural soil carbon and nitrogen dynamics have not been sufficiently reported. In an attempt to remedy this, we conducted a 105-day out-door mesocosm experiment in a soil-plant system using sandy soils amended with two types of MPs, low-density polyethylene (LDPE-MPs) and biodegradable (Bio-MPs), at concentrations of 0.0% (control), 0.5%, 1.0%, 1.5%, 2.0% and 2.5% (w/w, weight ratio of microplastics to air-dry soil). Soil organic matter (SOM), dissolved organic carbon (DOC), permanganate oxidizable carbon (POXC), available nitrogen (AN) of N-NH4+ and N-NO3−, and dissolved organic nitrogen (DON) were measured on day 46 (D46) and 105 (D105) of the experiment. SOM was also measured after microplastics were mixed into soils (D0). For LDPE-MPs treatments, SOM on D0, D46 and D105 showed no significant differences, while for Bio-MPs treatments, SOM significantly (p < 0.05) decreased from D0 to D46. Compared to the control, soil POXC was significantly (p = 0.001) lowered by 0.5%, 1.0% and 2.5% LDPE-MPs and ≥1.0% Bio-MPs on 105d. LDPE-MPs showed no significant effects on soil DOC and nitrogen cycling. 2.0% and 2.5% Bio-MPs showed significantly higher (p < 0.001) DOC and DON (D46 and D105) and ≥1.5% Bio-MPs showed significantly lower (p = 0.02) AN (D46). Overall, Bio-MPs exerted stronger effects on the dynamics of soil carbon and nitrogen cycling. In conclusion, microplastics might pose serious threats to agroecosystems and further research is needed.
220. 题目: An integrated active biochar filter and capacitive deionization system for high-performance removal of arsenic from groundwater
期刊: Journal of Hazardous Materials
作者: Dinh Viet Cuong, Po-Chang Wu, Sofia Ya Hsuan Liou, Chia-Hung Hou
摘要: An integrated process of filtration and electrosorption was first applied to enable high-performance arsenic removal for groundwater remediation. An active manganese dioxide-rice husk biochar composite (active BC) filter was utilized for oxidization of As(III) to As(V) and initial removal of As(III, V). Subsequently, electrosorption by capacitive deionization (CDI) was applied as a posttreatment to improve arsenic removal. The active BC approach exhibited fast removal rates of 0.75 and 0.63gmg–1 h–1 and high maximum removal capacities of 40.76 and 48.15mgg–1 for As(III) and As(V), respectively. Importantly, column experiments demonstrated that the arsenic removal capacity in the active BC filter was 2.88mgg–1, which was 72 times higher than that of BC. The results were due to the high efficiency (94%) of redox transformation of As(III) to As(V). The electrosorptive removal of arsenic was further controlled by changing the voltage in CDI. With a charging step of 1.2V, the total arsenic concentration can be reduced to 0.001mgL–1 with a low energy consumption of 0.0066 kWh m−3. Furthermore, the integrated system can remove As from the real groundwater to achieve the World Health Organization guideline value for drinking water quality.