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25281. 题目: Preparation, characterization, and application of magnetic activated carbon for treatment of biologically treated papermaking wastewater
文章编号: N20011802
期刊: Science of The Total Environment
作者: Zhuqing Feng, Huilun Chen, Haiqing Li, Rongfang Yuan, Fei Wang, Zhongbing Chen, Beihai Zhou
更新时间: 2020-01-18
摘要: In view of the urgent need for tertiary treatment of papermaking wastewater and the difficulty in separating powdered activated carbon (PAC) from water, the magnetic activated carbon (33%-MPAC, 50%-MPAC and 67%-MPAC) were prepared by chemical coprecipitation method for adsorption of biologically treated papermaking wastewater (BTPW). A series of characterization of MPAC and PAC were carried out and show that the content of iron oxides is negatively related to the proportion of micropores in MPAC. The loaded iron oxides is mainly the mixture of magnetite and maghemite, and the maximum saturation magnetization of MPAC can reach 29.68 emu/g. Batch mode experiments were performed, and found that the adsorption effect of MPAC is slightly worse than that of PAC, the adsorption capacity of COD in MPAC can reach about 65 mg/g, and pH = 2 and 10 °C are more favorable for adsorption. The adsorption isotherms and kinetics were well fitted by the Freundlich model and pseudo-second-order kinetic model, respectively. The selective adsorption was studied by using the excitation emission matrix (EEM) fluorescence spectrum and high-performance size exclusion chromatography (HPSEC). It is concluded that all adsorbents are preferred to adsorb humic acid-like substances (HA). And all adsorbents are preferred to adsorb low apparent molecular weight substances (LAMW, AMW < 1500 Da), with the increase of iron oxides content, the phenomenon of MPAC preferentially adsorbed LAMW became less obvious.
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25282. 题目: Tillage induces rapid loss of organic carbon in large macroaggregates of calcareous soils
文章编号: N20011801
期刊: Soil and Tillage Research
作者: Yingying Ye, Shuangshuang Xiao, Shujuan Liu, Wei Zhang, Jie Zhao, Hongsong Chen, Georg Guggenberger, Kelin Wang
更新时间: 2020-01-18
摘要: Soil organic carbon (SOC) sequestration and protection not only mitigate CO₂ emission but also promote soil fertility. Naturally, calcareous soils in the karst area contain significantly higher SOC concentration than the red soils in non-karst area of the same region. After cultivation, calcareous soils are susceptible to SOC loss, with substantial SOC loss occurring within two years. However, the underlying mechanisms are not well understood. To expand our understanding of the process of rapid SOC loss and the role played by soil aggregate disruption, we conducted a 1-year in situ study in a karst area in Southwest China. We tilled the soil at different intervals—every 6 (T1), 4 (T2), 2 (T3), and 1 (T4) months—causing aggregate disruption of different intensities. No-tillage soil (T0) was treated as a control. After 1 year, the SOC concentration in the soil under the tillage treatments (T1, T2, T3, and T4) was significantly reduced; however, in the no-tillage soil, no significant change was observed. The SOC loss within the first 3 months accounted for approximately 70 %–84 % of the total SOC loss, indicating that SOC loss was most pronounced during the initial tillage period. SOC was mainly stored in the 2–8 mm soil aggregates. Tillage-induced disruption of the 5–8 mm aggregates resulted in a decline of the physical protection of SOC, leading to substantial SOC loss from these aggregates. Besides, the SOC loss was positively correlated to the amount of Ca²⁺ leaching, indicating that enhanced carbonate dissolution might contribute to the decline in aggregate stability and associated SOC loss. Our results emphasize the importance of zero-tillage management and maintenance of large soil macroaggregates for sustainable land use of calcareous soils in karst regions.

25283. 题目: Biogeochemistry and dynamics of particulate organic matter in a shallow-water hydrothermal field (Kueishantao Islet, NE Taiwan)
文章编号: N20011706
期刊: Marine Geology
作者: Yu-Shih Lin, Jay Lee, Li-Hung Lin, Ke-Hsien Fu, Chen-Tung Arthur Chen, Yu-Huai Wang, I-Huan Lee
更新时间: 2020-01-17
摘要: The particulate organic matter (POM) of shallow-water hydrothermal fields has been studied in the context of food web reconstruction, but the processes governing its biogeochemistry and dynamics are poorly explored. Here, we investigate the POM in the Kueishantao hydrothermal field using chemical and hydrodynamic approaches. The depletion of total suspended matter, lower C/N ratios, and higher carbon isotopic values of particulate organic carbon (δ13CPOC) in the vertical plumes relative to values derived from Si-based models were attributed to the hydraulic sorting of the vented particles, which tend to have more N and 13C in the fine fraction. The particulate organic carbon (POC), unlike the total suspended matter, was enriched in the vertical plumes and explained by physicochemical processes rather than biological addition. The POC-enriched plume-top water was found to be a better endmember than the vent fluids to explain particle mixing in the lateral plume. Physical mixing played a steering role in shaping the particle chemistry of the lateral plumes, but markedly 13C-enriched POC was still observable in several near-vent, low-to-intermediate-Si plume waters, implying locally enhanced primary production of at least 0.1–0.4 mg C/m3/h. The presence of eddies, confirmed by flow field measurements, should have contributed to the detection of biogeochemical anomalies via extending the retention time of plume water to 1–2 h. The dominating mixing process resulted in decoupling between the δ13CPOC signatures and carbonate chemistry in this shallow-water hydrothermal plume.

25284. 题目: Complexation by Organic Matter Controls Uranium Mobility in Anoxic Sediments
文章编号: N20011705
期刊: Environmental Science & Technology
作者: Sharon E. Bone, John Cliff, Karrie Weaver, Christopher J. Takacs, Scott Roycroft, Scott Fendorf, John R. Bargar
更新时间: 2020-01-17
摘要: Uranium contamination threatens the availability of safe and clean drinking water globally. This toxic element occurs both naturally and as a result of mining and ore-processing in alluvial sediments, where it accumulates as tetravalent U [U(IV)], a form once considered largely immobile. Changing hydrologic and geochemical conditions cause U to be released into groundwater. Knowledge of the chemical form(s) of U(IV) is essential to understand the release mechanism, yet the relevant U(IV) species are poorly characterized. There is growing belief that natural organic matter (OM) binds U(IV) and mediates its fate in the subsurface. In this work, we combined nanoscale imaging (nano secondary ion mass spectrometry and scanning transmission X-ray microscopy) with a density-based fractionation approach to physically and microscopically isolate organic and mineral matter from alluvial sediments contaminated with uranium. We identified two populations of U (dominantly +IV) in anoxic sediments. Uranium was retained on OM and adsorbed to particulate organic carbon, comprising both microbial and plant material. Surprisingly, U was also adsorbed to clay minerals and OM-coated clay minerals. The dominance of OM-associated U provides a framework to understand U mobility in the shallow subsurface, and, in particular, emphasizes roles for desorption and colloid formation in its mobilization.

25285. 题目: Promoting the photogeneration of hydrochar reactive oxygen species based on FeAl layered double hydroxide for diethyl phthalate degradation
文章编号: N20011704
期刊: Journal of Hazardous Materials
作者: Quanyun Ye, Zhiyan Huang, Pingxiao Wu, Jiayan Wu, Jiaxin Ma, Chenhui Liu, Shanshan Yang, Saeed Rehman, Zubair Ahmed, Nengwu Zhu, Zhi Dang
更新时间: 2020-01-17
摘要: Improving the photocatalytic capacity of hydrochar to apply in wastewater treatment is of great significance. In this study, a novel heterogeneous photocatalytic material was prepared by compounding hydrochar with FeAl layered double hydroxide (FeAl-LDH). Furthermore, hydrochar was separated into hydrochar carbon matrix (HCM) and dissolved organic matter (DOM) to analyse their contribution in the reactive oxygen species (ROS) generation. The characterization and photocatalytic property of three composites (hydrochar-LDH, HCM-LDH and DOM-LDH) were investigated. The results showed that three composites were successfully synthesized with the formation of nano-sized LDH, graphitic carbon and oxygen vacancies. Persistent free radicals (PFRs) existed in hydrochar and the amount of them increased distinctly with the presence of FeAl-LDH. The degradation efficiency of DEP by hydrochar-LDH, HCM-LDH and DOM-LDH was 5.0, 4.2 and 1.5 times than that of hydrochar within 180 min, respectively. The reasons were proposed as: (i) Both HCM-LDH and DOM-LDH could induce the formation of •OH, O₂•- and ¹O₂, while HCM-LDH was the main contributor to generate O₂•- and •OH; (ii) HCM-LDH possessed many oxygenated functional groups, which were key factors affecting the formation of ROS; (iii) Fe could enhance the electron transfer process during the photoreaction, promoting the formation of ROS.
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25286. 题目: Occurrence, distribution, and source track of antibiotics and antibiotic resistance genes in the main rivers of Chongqing city, southwest China
文章编号: N20011703
期刊: Journal of Hazardous Materials
作者: Gangan Wang, Shaohong Zhou, Xinkuan Han, Lilan Zhang, Shiyuan Ding, Yang Li, Daijun Zhang, Kinza Zarin
更新时间: 2020-01-17
摘要: In this study, the occurrence of 14 antibiotics, four corresponding antibiotic resistance genes (ARGs) and two microbial source tracker (MST) indicators were analyzed in two rivers of Chongqing city, southwest China. The results showed that 13 antibiotics were detected in all 12 sites and their detection frequencies were much higher in September, but concentrations were lower than that in March. Of them, erythromycin (ETM) and ofloxacin (OFL) were the predominant antibiotics in both seasons. The remarkably higher concentration of antibiotics in sediments of these rivers than those in other rivers were found. Environmental risk assessment found that four antibiotics posed high risk toward some sensitive algae. For ARGs, their relative abundances were higher in waters than those in sediments, higher in March than in September. Correlation analysis showed that antibiotics were not the exclusive selective pressure of ARGs; many environmental factors like dry matter contents on a mass basis, organic matter, total organic carbon, dissolved organic carbon, temperature, oxidation reduction potential and nitrite could affect the occurrence of ARGs. MST indicators analysis demonstrated that this river basin was largely polluted by human and pig feces, and human feces might be one main source of the four ARGs and five antibiotics.
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25287. 题目: Lead competition alters the zinc adsorption mechanism on animal-derived biochar
文章编号: N20011702
期刊: Science of The Total Environment
作者: Cong Xue, Ling Zhu, Sicong Lei, Mengping Liu, Chengyi Hong, Lei Che, Junliang Wang, Yuping Qiu
更新时间: 2020-01-17
摘要: In this study, the adsorption behaviors and mechanisms of Pb(II) and Zn(II) by animal-derived biochar (ADB) in single and binary metal systems were comparatively investigated. ADB contains considerable amounts of Ca/P components and is mainly composed of hydroxyapatite (HAP), which plays an important role in the adsorption of Pb(II) and Zn(II). The maximum adsorption capacities of Pb(II) and Zn(II) on ADB were in the order of Zn(II)-single (3.23 mmol g⁻¹) > Pb(II)-single (2.74 mmol g⁻¹) ≈ Pb(II)-binary (2.71 mmol g⁻¹) > Zn(II)-binary (2.31 mmol g⁻¹). In the single metal system, approximately 99.9% of the adsorbed Pb(II) existed as Pb₅(PO₄)₃Cl, while the dominant adsorption mechanism of Zn(II) was cation exchange, followed by precipitation, accounting for 78.0%–80.6% and 19.4%–21.5% of the adsorption capacity, respectively. These findings were verified by X-ray diffraction refinement, X-ray photoelectron spectroscopy, metal speciation modeling, and Ca(II) exchange experiment. In the binary metal system, the proportion and form of Pb(II) precipitate remained unchanged. However, the binding of Zn(II) to ADB was completely dependent on the cation exchange with Ca(II), and no remarkable Zn(II) precipitation was observed. Phosphate released from HAP preferentially precipitated with Pb(II) than with Zn(II) when they coexisted. Consequently, Pb(II) competition may alter the Zn(II) adsorption mechanism on ADB. Nonetheless, ADB could serve as an efficient biochar for the simultaneous immobilization of Pb(II) and Zn(II) via different mechanisms.
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25288. 题目: Cotransport and deposition of biochar with different sized-plastic particles in saturated porous media
文章编号: N20011701
期刊: Science of The Total Environment
作者: Meiping Tong, Tengfei Li, Meng Li, Lei He, Zhiyao Ma
更新时间: 2020-01-17
摘要: Plastic particles recently are reported to be ubiquitous in natural environments, while biochar is widely employed as an amendment into natural environments e.g. soil for pollution remediation. It is highly likely their transport behaviors in porous media would be altered due to interaction with each other. In this study, the cotransport and deposition behaviors of biochar and plastic particles (0.02 μm nanoplastics (NPs), 0.2 μm and 2 μm micrometer-plastics (MPs)) in quartz sand were investigated at both low (5 mM) and high ionic strength (25 mM) in NaCl solutions at pH 6. The results demonstrated that smaller sized plastic particles (0.02 μm NPs and 0.2 μm MPs) increased biochar transport under both 5 and 25 mM NaCl solutions, while large plastic particles (2 μm MPs) increased biochar transport in 5 mM NaCl solutions yet decreased biochar transport in 25 mM NaCl solutions. For all sized plastic particles, biochar significantly decreased their transport at both low (5 mM) and high (25 mM) ionic strengths in NaCl solutions. The change of zeta potentials of biochar due to heteroaggregation with plastic particles, and the steric repulsion induced by the suspended plastic particles contributed to the enhanced biochar transport with the copresence of smaller sized plastic particles (0.02 μm NPs and 0.2 μm MPs). While, the cotransport of biochar with 2 μm MPs due to their heteroaggregation contributed to the varied transport behaviors of biochar observed at low and high ionic strength with the copresence of 2 μm MPs. The formation of plastic particles-biochar heteroaggregates drove to the decreased transport of all three different sized plastic particles with the copresence of biochar. Considering the coexistence of biochar and plastic particles in natural environment, they would interact with each other (form heteroaggregates) and thus lead to the change of transport behaviors in porous media.
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25289. 题目: Variations in Colloidal DOM Composition with Molecular Weight within Individual Water Samples as Characterized by Flow Field-Flow Fractionation and EEM-PARAFAC Analysis
文章编号: N20011612
期刊: Environmental Science & Technology
作者: Hui Lin, Laodong Guo
更新时间: 2020-01-16
摘要: Fluorescence excitation emission matrices (EEM) and parallel factor (PARAFAC) analysis have been widely used in the characterization of dissolved organic matter (DOM) in the aquatic continuum. However, large sample sets are typically needed for establishing a meaningful EEM-PARAFAC model. Applications of the EEM-PARAFAC technique to individual samples require new approaches. Here, flow field-flow fractionation (FlFFF) combined with offline EEM measurements and PARAFAC analysis was used to elucidate the dynamic changes in DOM composition/optical properties with molecular weight within individual samples. FlFFF-derived size spectra of ultrafiltration-isolated colloidal DOM show that peak-C related fluorophores (Ex/Em= 350/450 nm) are present mostly in the 1–3 kDa size range, while peak-T associated fluorophores (Ex/Em = 275/340 nm) have a bimodal distribution with peaks in both the 1–3 kDa and the >100 kDa size fractions. The integrated EEM spectra from FlFFF size-fractionated subsamples closely resembled the bulk EEM spectra, attesting to the convincing comparability between bulk and FlFFF size-fractionated EEMs. The PARAFAC-derived DOM components are distinctive among individual samples with the predominant components being humic-like in river water, but protein-like in a highly eutrophic lagoon sample. This compelling new approach combining FlFFF and EEM-PARAFAC can be used to decipher the dynamic changes in size spectra and composition of individual DOM samples from sources to sinks or across the redox/hydrological/trophic interfaces.

25290. 题目: Excitation-emission matrix (EEM) fluorescence spectroscopy for characterization of organic matter in membrane bioreactors: Principles, methods and applications
文章编号: N20011611
期刊: Frontiers of Environmental Science & Engineering
作者: Jinlan Yu, Kang Xiao, Wenchao Xue, Yue-xiao Shen, Jihua Tan, Shuai Liang, Yanfen Wang, Xia Huang
更新时间: 2020-01-16
摘要: The membrane bioreactor (MBR) technology is a rising star for wastewater treatment. The pollutant elimination and membrane fouling performances of MBRs are essentially related to the dissolved organic matter (DOM) in the system. Three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy, a powerful tool for the rapid and sensitive characterization of DOM, has been extensively applied in MBR studies; however, only a limited portion of the EEM fingerprinting information was utilized. This paper revisits the principles and methods of fluorescence EEM, and reviews the recent progress in applying EEM to characterize DOM in MBR studies. We systematically introduced the information extracted from EEM by considering the fluorescence peak location/ intensity, wavelength regional distribution, and spectral deconvolution (giving fluorescent component loadings/scores), and discussed how to use the information to interpret the chemical compositions, physiochemical properties, biological activities, membrane retention/fouling behaviors, and migration/ transformation fates of DOM in MBR systems. In addition to conventional EEM indicators, novel fluorescent parameters are summarized for potential use, including quantum yield, Stokes shift, excited energy state, and fluorescence lifetime. The current limitations of EEM-based DOM characterization are also discussed, with possible measures proposed to improve applications in MBR monitoring.

25291. 题目: Biogeochemical processes accounting for the natural mercury variations in the Southern Ocean diatom ooze sediments
文章编号: N20011610
期刊: Ocean Science
作者: Sara Zaferani, Harald Biester
更新时间: 2020-01-16
摘要: Understanding the marine biogeochemical cycle of mercury is crucial as consumption of mercury enriched marine fish is the most important pathway of mercury uptake by humans. However, due to the lack of long term marine records, the role of the oceans in the global mercury cycle is poorly understood and we do not have well documented data of natural mercury accumulations during changing environmental conditions, e.g. sea surface conditions in the ocean. To understand influence of different sea surface conditions (climate induced changes in ice coverage and biological production) on natural mercury accumulation, we used a continuous ~ 170 m Holocene biogenic sedimentary record from Adélie Basin, East Antarctica, which mainly consists of silica based skeletons of diatoms. We performed Principal Component Analysis and regression analysis on element concentrations and corresponding residual of element concentrations, respectively to investigate the link between sediment mercury accumulation, terrestrial inputs, and productivity. Preindustrial mercury accumulation in the remote pristine marine Antarctica showed extremely high accumulation rates (median: 556 µg m−2 yr−1) that displayed periodic-like variations. Our analysis shows that the variations in total mercury concentrations and accumulation rates are associated with biological production and related scavenging of available water phase mercury by rapidly sinking algae or algae derived organic matter after intense algae blooms. High accumulation rates of other studied elements further revealed that in regions of high primary productivity, settling of biogenic materials removes many other elements from ocean surface (through scavenging or biological uptake). In conclusion, the link between mercury cycling and primary production will need to be considered in future studies of the marine mercury cycle under future primary production enhancement through climatic, temperature, and nutrient availability changes.

25292. 题目: In‐lake transformations of dissolved organic matter composition in a subalpine lake do not change its biodegradability
文章编号: N20011609
期刊: Limnology and Oceanography
作者: Masumi Stadler, Elisabet Ejarque, Martin J. Kainz
更新时间: 2020-01-16
摘要: In freshwater ecosystems, dissolved organic matter (DOM) originates from terrestrial and aquatic primary production, and its microbial biodegradability is expected to vary due to differences in its biogeochemical composition. However, the interaction of various DOM sources with the aquatic microbial population remains widely debated. Here, we performed laboratory bioassays, conducted in the dark for 20 d, to examine how changes in DOM composition influence its microbial biodegradability along a hydrological continuum (i.e., lake inlet, lake layers, and lake outlet) of a subalpine lake over four seasons. Despite a predominance of terrestrial DOM and lowest initial abundance of microorganisms, the highest microbial growth rates were observed at the lake inlet (0.0076 ± 0.0011 cells mL⁻¹ h⁻¹) across all seasons. DOM reactivity differed more with time (seasons) than with space (sampling sites) and DOM compositional differences showed higher degradability in upper lake layers, but not at the lake outlet. Additionally, gradual humification over incubation time was observed in almost all seasons and sites. Overall, an enhanced biodegradability of DOM was not detected even though lake sites were characterized by an autochthonous, presumably labile DOM signature. However, our results highlight the potential of thriving bacteria in terrestrial‐dominated DOM environments. This observation challenges a previous hypothesis that DOM of terrestrial origin is less accessible and more recalcitrant, while emphasizing the flexible response of aquatic systems to seasonal fluctuations.

25293. 题目: Revisiting no-till’s impact on soil organic carbon storage in Canada
文章编号: N20011608
期刊: Soil and Tillage Research
作者: B.C. Liang, A.J. VandenBygaart, J.D. MacDonald, D. Cerkowniak, B.G. McConkey, R.L. Desjardins, D.A. Angers
更新时间: 2020-01-16
摘要: Accurate estimates of soil organic carbon (SOC) stock change as influenced by tillage practices are prerequisites to quantify the impact of mitigation measures on greenhouse gas emissions associated with crop production. In this study, we compiled SOC stock change data as influenced by tillage practices, i.e. no-till (NT) versus conventional tillage (CT), on agricultural soils in Canada. We determined the rate of C change as a function of soil texture and climate stratified by time since the management change. In the cool and humid climates of Eastern Canada, the impacts of NT were inconsistent and resulted in a decline in C storage rate in the years shortly following management change, but SOC recovered over time. Carbon losses were particularly high on fine and coarse textured soils, whereas in medium textured soils NT tended to increase SOC. On the Canadian prairies NT consistently increased SOC. The rate of gain in SOC under NT decreased over time with higher rates in the 3−10 years following a change to NT at a rate of 740 kg C ha⁻¹ yr⁻¹ or 1.3 % yr⁻¹. Rates declined to 260 kg C ha⁻¹ yr⁻¹ or 0.87 % yr⁻¹ for periods from 11–20 years after tillage change, and to 95 kg C ha^-1 yr⁻¹ or 0.23 % for periods longer than 20 years. The results of this work clearly show climate, soil texture and duration of management as main drivers of SOC change under NT in Canada and key factors that must be considered in the development of either national or regional SOC models. The results of this study suggest that more detailed stratification of soil texture, climate and duration of NT adoption is required for more accurate estimates of SOC storage rates associated with NT for Canada.

25294. 题目: Different life-form plants exert different rhizosphere effects on phosphorus biogeochemistry in subtropical mountainous soils with low and high phosphorus content
文章编号: N20011607
期刊: Soil and Tillage Research
作者: Denggao Fu, Xiaoni Wu, Changqun Duan, Luoqi Zhao, Bo Li
更新时间: 2020-01-16
摘要: Soil phosphorus (P) is among the most important but least understood nutrients supporting the productivity and function of terrestrial ecosystems. To understand soil P cycling, it is essential to quantify the effects of plants on soil P fractions (labile inorganic P [Pi], intermediately available Pi, organic P, and occluded P). The study aimed to compare how the rhizosphere effect of different life-form plants influences P fractions in P-depleted and P-enriched soils in southwest China’s subtropical mountainous region. For all three selected species (native conifer, Pinus yunnanensis; native shrub, Myrsine africana; invasive herb: Eupatorium adenophorum), total P and P-fraction concentrations were much higher in the high-P site than in the low-P site. Occluded and organic P were the dominant fractions at the low-P site, while occluded and intermediate P were the dominant P fractions at the high-P site. Species identity significantly affected all five soil P fractions in both sites, except organic P at the high-P site. Total P, labile P, and intermediate P changed significantly with time. Additionally, plants were able to increase the rhizosphere effect on labile and intermediate P at the low-P site, as well as organic P at the high-P site. Eupatorium adenophorum exerted a significantly positive rhizosphere effect on labile and intermediate P at the low-P site, as well on labile P and organic P in the high-P site. Thus, compared with native M. africana and P. yunnanensis, the invasive E. adenophorum can more effectively alter rhizosphere soil P fractions in response to different soil P levels. Linear regression showed that the rhizosphere effect on labile P was correlated with the rhizosphere effect on pH, and the rhizosphere effect on organic P was related to the rhizosphere effect on soil organic matter and exchangeable Fe_ox and Al_ox. In conclusion, different life-form plants generally exert a different rhizosphere effect through geochemical and biological processes, thus influencing P biogeochemical cycling in different soil P contents.

25295. 题目: Phytoremediation of heavy metals under an oil crop rotation and treatment of biochar from contaminated biomass for safe use
文章编号: N20011606
期刊: Chemosphere
作者: J. Zhou, L.H. Chen, L. Peng, S. Luo, Q.R. Zeng
更新时间: 2020-01-16
摘要: The disposal of contaminated plants limits the use of phytoremediation. Therefore, the disposal of contaminated sunflower was investigated after determining the phytoremediation of heavy metals under an oil crop rotation of sunflower (Helianthus annuus L)–sesame (Sesamum indicum L.). In the field experiment, the extraction efficiency of sunflower-sesame rotation was 0.07% for lead (Pb); 1.37% for zinc (Zn); 1.10% for copper (Cu); and 6.12% for cadmium (Cd). Contaminated sunflower stems were pyrolyzed at different temperature. The biochar produced at 300 °C was extracted in a two-step process (acid-extraction from biochar and metals precipitation in alkaline condition). At pH = 1, 65.67% of the Cd and much potassium (K) were extracted. After acid-extraction, adjust the pH of filtrate to 10, metals were precipitated and then separated from the K-enriched solution. Therefore, pyrolysis can process contaminated residues, and the biochar extracts can be reutilized as fertilizer to off-site crop production. Thus, an oil crop-rotation system, in addition to creating economic benefits, can be used by local farmers in contaminated soils.
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25296. 题目: Long term anthropogenic enrichment of soil organic matter stocks in forest soils – Detecting a legacy of historical charcoal production
文章编号: N20011605
期刊: Forest Ecology and Management
作者: Alexander Bonhage, Florian Hirsch, Anna Schneider, Alexandra Raab, Thomas Raab, Sally Donovan
更新时间: 2020-01-16
摘要: Recent findings of several thousand relict charcoal hearths (RCHs) in the Tauer Forest (Brandenburg, Germany) raise questions about the legacy effects of historical charcoal production on soil properties. RCH sites are characterized by the admixture of charcoal fragments to the natural forest soil, constituting an anthropogenic addition of carbon. Dendrochronological dating of large charcoal pieces has identified RCH ages ranging from 1709 CE to 1823 CE for a subarea in the Tauer Forest, which allows for assessing century old effects of charcoal application on forest soils. We measured the geometry and soil organic matter (SOM) content of 20 RCH sites in a selected part of the forest. The results provide a basis for estimating RCH SOM stocks on a 40-ha forest plot with 120 RCH sites. We also assessed the accuracy of RCH mapping based on digital elevation models (DEMs) with results from a ground survey. Over 50 % of sites were not detected by the DEM-based mapping. In the range of statistical uncertainties, RCHs add between 18 % and 32 % of SOM to the stock of the natural forest soil in the study area. This equals an additional 4.9–8.9 Mg of carbon per hectare of forest soil. These substantial amounts of SOM are so far not recognized by any survey or forest soil SOM inventories. Considering recent studies, which uncovered tens- and hundreds- of thousands of RCHs throughout Europe and the USA, we conclude that further knowledge of RCH SOM is important for quantifying anthropogenic SOM stocks on a global scale.

25297. 题目: Investigating the cycling of chromium in the oxygen deficient waters of the Eastern Tropical North Pacific Ocean and the Santa Barbara Basin using stable isotopes
文章编号: N20011604
期刊: Marine Chemistry
作者: Simone B. Moos, Edward A. Boyle, Mark A. Altabet, Annie Bourbonnais
更新时间: 2020-01-16
摘要: Cr isotope geochemistry is being explored in the context of a variety of geological problems as well as the environmental remediation of pollutant Cr(VI). There is a strong Cr isotope fractionation during reduction of oxidized Cr(VI) to reduced Cr(III). We present chromium concentration and Cr isotope data for samples from highly reducing environments ([O₂] < 2 μmol/kg) in the Eastern Tropical North Pacific (ETNP) Oxygen Deficient Zone (ODZ) off of Mexico and the deep Santa Barbara Basin off of California. Total dissolvable Cr in the upper ETNP ODZ is slightly depleted (by up to 0.8 nmol/kg) and δ⁵³Cr is up to 0.1–0.2‰ heavier compared to oxic waters of the same density seen at the SAFe station (30°N, 140°W), presumably both a result of reduction of Cr(VI) and removal of light Cr(III) by sinking particles. The Cr depletion and Cr isotope fractionation peak at the same depth as the highest δ¹⁵N of NO₃⁻ and decrease within the equally oxygen-deficient waters below, implying that microbial reduction dependent on the sinking organic matter flux may be the mechanism of Cr reduction. These data are consistent with a fractionation mechanism with a net isotope fractionation factor of ε ≈ −0.44‰. In the deepest anoxic waters of the Santa Barbara Basin in July 2014, dissolved (<0.2 μm) Cr is depleted by up to 1.8 nmol/kg and δ⁵³Cr is up to 0.5‰ heavier compared to SAFe station waters of the same density. This is consistent with a net isotope fractionation factor of ε ≈ −0.65‰. At the Santa Barbara Basin site, it is possible that abiotic Fe(II) reduction (from Fe(II) diffusing out of reducing continental shelf sediments) also contributes to Cr reduction in addition to the microbial reduction mechanism.

25298. 题目: Evaluation of change in biochar properties derived from different feedstock and pyrolysis temperature for environmental and agricultural application
文章编号: N20011603
期刊: Science of The Total Environment
作者: Priya Pariyar, Kanchan Kumari, Manish Kumar Jain, Pradip S. Jadhao
更新时间: 2020-01-16
摘要: In recent years, the application of biochar has increased significantly for sustainable and efficient carbon sequestration, improving soil quality and enhancement of plant growth. The biochar is mostly made from agricultural residues and waste materials. The objective of this study was to assess the changes in physicochemical, surface morphology, and mineral composition of different biochars with varying pyrolysis temperature. Eighteen different types of biochars were prepared through pyrolysis of feedstock at four different temperatures (350 °C, 450 °C, 550 °C and 650 °C). The feedstock used for the preparation of biochar were organic waste materials such as pine saw dust, rice husk, food waste, poultry litter and paper sludge. Pyrolysis temperatures and feedstock types significantly influenced biochar properties. For instance, pH of poultry litter and paper sludge biochar has increased from 6.2 to 10.3, BET surface area of saw dust and rice husk increased from 3.39 to 443.79 m² g⁻¹ and 11.61 to 280.97 m² g⁻¹ while cation exchange capacity value decreased with the increase in temperature. Paper sludge and poultry litter had the highest ash content value (57.20 ± 0.02 and 44.10 ± 0.02) whereas saw dust, rice husk and food waste biochar have highest fixed carbon value (55.31 ± 0.15, 48.47 ± 0.31 and 58.85 ± 0.22) at 650 °C. Degree of aromaticity increased and polarity reduced significantly with pyrolysis temperature. Rice husk and saw dust biochar prepared at higher temperature were more stable among all and thus recalcitrant in nature. X-ray diffraction results revealed mineral like quartz in saw dust and poultry litter biochar, sylvite, potassium iodate, calcium sulfide in food waste biochar and calcium carbonate in paper sludge biochar. Scanning Electron Microscopy showed increase in number of pores as well as pore size specially for the saw dust, and rice husk biochar. This study suggested that biochar prepared at higher temperature (550 °C and 650 °C) are more suitable for carbon sequestration and agricultural purpose.
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25299. 题目: Biochar surface complexation and Ni(II), Cu(II), and Cd(II) adsorption in aqueous solutions depend on feedstock type
文章编号: N20011602
期刊: Science of The Total Environment
作者: Siyuan Wang, Jin-Hyeob Kwak, Md Shahinoor Islam, M. Anne Naeth, Mohamed Gamal El-Din, Scott X. Chang
更新时间: 2020-01-16
摘要: Biochar is a promising material for efficient removal of toxic metals from wastewater to meet standards for discharge into surface water. We characterized adsorption behaviour of willow (Salix alba) wood (WW) and cattle manure (CM) and their biochars, willow wood biochar (WWB) and cattle manure biochar (CMB), and elucidated the mechanisms for the removal of Ni(II), Cu(II) and Cd(II) from aqueous solutions. The kinetic adsorption suggests that the adsorption of Ni(II), Cu(II) and Cd(II) by feedstock and their biochars was controlled by mass transport, and chemisorption also played a role in the adsorption process. The Elovich model also well described the adsorption kinetics for WW and CM (R² > 0.92), indicating that heterogeneous diffusion was the mechanism. The Sips isotherm model fitted best (R² > 0.98) for Ni(II), Cu(II) and Cd(II) adsorption by the feedstocks and their biochars, indicating that both monolayer and multilayer adsorption played roles on the heterogeneous surfaces of the four adsorbents. The WWB had a higher while the CMB had a lower adsorption capacity than their respective feedstock due to the presence of abundant –COOH functional group on WWB surface to interact with Ni(II), Cu(II) and Cd(II) to form surface complexes. The higher specific surface area and lower pH of point of zero charge (PZC) of WWB were other contributing factors for its greater removal capacity. Therefore, we conclude that proper feedstocks need to be selected to produce biochars that are efficient for the removal of toxic metals from wastewater.
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25300. 题目: Suspended state heteroaggregation kinetics of kaolinite and fullerene (nC₆₀) in the presence of tannic acid: Effect of π-π interactions
文章编号: N20011601
期刊: Science of The Total Environment
作者: Qianyue Guo, Zhenquan Wang, Qijing Xu, Han Mao, Di Zhang, Saikat Ghosh, Nihar R. Pradhan, Bo Pan, Baoshan Xing
更新时间: 2020-01-16
摘要: The colloidal heteroassociation between natural mineral colloids and engineered nanoparticles (ENPs) can reduce the bioavailability and toxicity of the ENPs. However, the efficacy of this heteroassociation-based entrapment of ENPs depends on the intrinsic material properties of the particles and the physicochemical parameters of the aquatic environment. Natural organic matter (NOM)-induced surface modifications of clay colloids, functionalization of ENPs, and efficiency of counterions as effective coagulants profoundly affect the effectiveness of heteroaggregation-based attenuation of anthropogenic colloids. In this study, tannic acid (TA), a surrogate of NOM, prevented the edge-to-face self-association of sodium-saturated kaolinite (Na-kaolinite) at acidic pH, as evaluated from the transverse proton spin–spin relaxation data (T₂). Likewise, fullerene water suspension (FWS) adhesion to Na-kaolinite prevented the self-association of Na-kaolinite and enhanced the colloidal stability. At pH 4 and diffusion-limited aggregation regime salt concentrations, the Na-kaolinite and FWS heteroaggregation rates were lower than the Na-kaolinite homoaggregation rates, and eventually reached a plateau. The higher colloidal stability of the Na-kaolinite and FWS binary mixture than that of Na-kaolinite, regardless of stronger charge screening by Ca²⁺_, reflects steric stabilization. However, at pH 7, the increased electrostatic barrier reduces the feasibility of colloidal heteroassociation between Na-kaolinite and FWS; thus, higher salt concentrations are required to initiate aggregation. Weak adsorption of TA on Na-kaolinite at pH 7 facilitated stronger π-π interactions with FWS. All suspensions exhibited faster aggregate growth at pH 7 than pH 4, possibly due to the stronger cation response at pH 7. In situ atomic force microscopy imaging and line profile plots of Na-kaolinite, TA, and FWS mixture in CaCl₂ further corroborated the difference in the heteroaggregation rates observed at the two different pH values. Thus, TA-induced surface functionalization of FWS and the consequent increased electrostatic barrier to heteroassociation with Na-kaolinite may facilitate the environmental mobility of FWS in aquatic media.
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