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23681. 题目: Biochar enhances bioelectrochemical remediation of pentachlorophenol-contaminated soils via long-distance electron transfer
文章编号: N20020206
期刊: Journal of Hazardous Materials
作者: Xixi Cai, Yong Yuan, Linpeng Yu, Beiping Zhang, Jibing Li, Ting Liu, Zhen Yu, Shungui Zhou
更新时间: 2020-02-02
摘要: The soil bioelectrochemical system (SBES) is a promising biotechnology for the remediation of contaminated soils. However, the effective distance of pollutant removal in the SBES was usually limited in a few centimeters near the electrode surface. In this study, we used biochar as the model conductor to construct a conductive network with microbes in the soil matrix to extend the effective distance of pollutant removal in the SBES. Pentachlorophenol (PCP) was used as the representative contaminant to probe long-distance electron transfer facilitated by the networks. The removal of PCP and microbial community analyses at different distances toward the electrode were monitored. The results showed that PCP transformation in the SBES without biochar amendment mainly occurred within 4 cm around the electrode. However, the effective distance of ∼ 16 cm toward the electrode could be achieved for efficient PCP degradation in the SBES amended with highly conductive biochar. Microbial community analysis confirmed the establishment of bacteria-biochar networks, where Desulfitobacterium and Geobacter were enriched and spatially distributed in the biochar-amended SBES. The results demonstrate that long-distance electron transfer can be achieved in the biochar-amended soil matrix, and shed light on the development of bioelectrochemical strategy for efficient organic pollutant degradation in soils.
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23682. 题目: Fate of organic carbon burial in modern sediment within Yangtze River Estuary
文章编号: N20020205
期刊: Journal of Geophysical Research: Biogeosciences
作者: Xueshi Sun, Dejiang Fan, Huijie Liao, Yuan Tian
更新时间: 2020-02-02
摘要: Large river‐dominated margins play a potential key role in regulating global carbon cycle and budget relative to high terrestrial organic carbon (C_org) inputs and sediment accumulation rates. Here, bulk elements (C_org and TN), isotopic compositions (δ¹³C_org and δ¹⁵N), radioisotope ²¹⁰Pb, sedimentary grain size, pH, Eh, and physicochemical properties were analyzed on samples from the Yangtze River Estuary (YRE) to determine the mechanism involved in transporting sedimentary C_org offshore. In addition, nine box‐cores were analyzed to further reveal the potential effects of the declining sediment load on the modern depositional pattern of C_org. The statistical analyses indicate that the hydrodynamically‐driven sediment composition exerts a significant control on the transport, mobilization, and accumulation of sedimentary C_org from the river to the estuary, with respect to the redistribution of fine‐grained sediments. Furthermore, X‐radiographs and ²¹⁰Pb indicate that reworked environment dominates carbon burial in the Yangtze proximal deposit, while a stable sedimentary environment of C_org (3.50−5.58 g cm^‐2 yr^‐1) is observed in the Yangtze distal mud. Notably, the enhanced erosional inputs that contain terrestrial plant debris (mainly the coarse fractions), have tended to become important sources for C_org. Although reworked sediments in YRE are frequently exposed to oxygen during physical and biological processes, there appears to be a high potential for long‐term sedimentary C_org storage, due to its association with sediment particles (mainly the clay fractions) that provide physical protection against its degradation.

23683. 题目: Synthesis a graphene-like magnetic biochar by potassium ferrate for 17β-estradiol removal: Effects of Al₂O₃ nanoparticles and microplastics
文章编号: N20020204
期刊: Science of The Total Environment
作者: Ni Liu, Yunguo Liu, Xiaofei Tan, Meifang Li, Shaobo Liu, Xinjiang Hu, Peng Zhang, Mingyang Dai, Weihua Xu, Jun Wen
更新时间: 2020-02-02
摘要: A graphene-like magnetic biochar (GLMB) was synthesized using lotus seedpod and potassium ferrate with simple step and applied for E2 adsorption. GLMB was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS), Raman, X-ray diffraction (XRD), vibrating sample magnetometer (VSM) and BET surface area. Several common (solution pH, ionic strength, humic acid and foreign ions) and new (Al₂O₃ nanoparticles and microplastics (MPs)) water experiment conditions were investigated. Characterization results demonstrated that the sample was fabricated successfully and it possessed some graphene-like properties and a large surface area (828.37 m²/g). Adsorption results revealed that the pseudo-second-order kinetics and Langmuir isotherm models could provide a better description for E2 uptake behavior. The E2 adsorption capacity could be influenced by solution pH, ionic strength and SO₄²⁻ ions, and the effect of humic acid and background electrolyte (Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, NO₃⁻, PO₄³⁻) could be neglected. The presences of Al₂O₃/MPs significantly decreased the time to reach adsorption equilibrium for E2 adsorption on GLMB, but had no obvious improvement or inhibiting effects on E2 removal when the adsorption reached equilibrium. The adsorption mechanism for E2 adsorption on GLMB was multiple, which involving π-π interactions, micropore filling effects, electrostatic interaction. The regeneration experiments showed that GLMB possessed a good regeneration performance. Based on the experimental results and comparative analysis with other adsorbents, GLMB was an economical, high-efficiency, green and recyclable adsorbent for E2 removal from aqueous solution.
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23684. 题目: Efficient oxidation and adsorption of As(III) and As(V) in water using a Fenton-like reagent, (ferrihydrite)-loaded biochar
文章编号: N20020203
期刊: Science of The Total Environment
作者: Yifan Huang, Minling Gao, Yingxuan Deng, Zulqarnain Haider Khan, Xuewei Liu, Zhengguo Song, Weiwen Qiu
更新时间: 2020-02-02
摘要: The by-product of the traditional Fenton reaction, colloidal arsenic-‑iron oxide, is migratable and may cause secondary environmental pollution. This paper reported a new strategy involving oxidizing and immobilizing inorganic arsenic using the Fenton reaction, and avoiding the risk of secondary contamination. Lab synthesized ferrihydrite-loaded biochar (FhBC) was developed for oxidizing and binding As(III) and As(V) in aqueous solution. Batch experiments and a series of spectrum analysis (e.g., X-ray photoelectron spectroscopy [XPS], electron paramagnetic resonance [EPR], and Fourier transform infrared spectroscopy [FTIR]) were conducted to study the oxidizing or adsorption capacity and mechanism. The maximum adsorption capacity of FhBC for As(III) and As(V) is 1.315 and 1.325 mmol/g, respectively. In addition, FhBC has an efficient oxidizing capacity within a wide pH range, which is because biochar promotes the Fenton reaction by acting as an electron donator, electron shuttler, or by providing persistent free radicals. Moreover, the adsorption mechanism was studied by FTIR spectroscopy, XPS, and X-ray diffraction (XRD). The formation of internal spherical complexes and iron oxides with a higher degree of crystallization was observed, which indicate that the products of adsorption are stable and robust in a complex environment and can exist in a highly crystallized form after adsorbing arsenic ions. Therefore, the use of FhBC as an adsorbent for arsenic represents a new strategy of using the Fenton reaction while reducing secondary contamination. These results may contribute to further mechanistic studies or extensive practical applications of FhBC.
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23685. 题目: Vegetation affects photoprotective pigments and copepod distribution in the Himalayan lakes: Implication for climate change adaptation
文章编号: N20020202
期刊: Science of The Total Environment
作者: Shaikhom Inaotombi, Debajit Sarma
更新时间: 2020-02-02
摘要: Lakes in the Himalayas host unique biota and biological communities which are highly sensitive to climate change. High penetration of solar UV radiation in clear shallow lake affects the distribution and abundance of the zooplankton communities. Survival of copepods in such habitats often relies on available photoprotective compounds. We estimated species diversity and distribution patterns of copepods with detectable carotenoids in 7 lakes of the central Himalayas along the altitudinal gradients. To determine the factors influencing the accumulation of high-level photoprotective compounds, we analyzed the physicochemical parameters of water and the concentration of Lignin like Compounds (LLCs), Aromaticity (ARO), Humic Compounds (HCs), Degree of Humification (DoH) and percent Total Organic Matter (TOM) in littoral sediments. In the shallow lakes, copepod abundance and diversity correlate with water transparency. Humic compounds (HCs) derived from ligninaceous plants stimulate the accumulation of photoprotective compounds that allow for the domination of diaptomidae. Copepods receive photoprotective compounds from the humic-bounded sediment substrate. The amount of photoprotectants in the aquatic food chain of the central Himalayas is largely influenced by ligninaceous compounds derived from catchment vegetation. In copepods of shallow clear lakes, the remnant of dead trees in the littoral zones helps to minimize hazards caused by exposure effect and climatic stress. The reduction of vegetative covers in the shorelines may alter the community structure of zooplankton, particularly in the upland ecosystem.
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23686. 题目: Terrestrial organic matter input drives sedimentary trace metal sequestration in a human-impacted boreal estuary
文章编号: N20020201
期刊: Science of The Total Environment
作者: Sami A. Jokinen, Tom Jilbert, Rosa Tiihonen-Filppula, Karoliina Koho
更新时间: 2020-02-02
摘要: Coastal sediments play a fundamental role in processing anthropogenic trace metal inputs. Previous studies have shown that terrestrial organic matter (OM) is a significant vector for trace metal transport across the land-to-sea continuum, but little is known about the fate of land-derived metal-OM complexes in coastal sediments. Here, we use a comprehensive set of sediment pore water and solid-phase analyses to investigate how variations in terrestrial OM delivery since the 1950s have influenced trace metal accumulation and diagenesis in a human-impacted boreal estuary in the northern Baltic Sea. A key feature of our dataset is a strong correlation between terrestrial OM deposition and accumulation of metal-OM complexes in the sediments. Based on this strong coupling, we infer that the riverine input of terrestrial metal-OM complexes from the hinterland, followed by flocculation-induced settling in the estuary, effectively modulates sedimentary trace metal sequestration. While part of the trace metal pool associated with these complexes is efficiently recycled in the surface sediments during diagenesis, a substantial fraction is permanently buried as refractory metal-OM complexes or through incorporation into insoluble sulfides, thereby escaping further biological processing. These findings suggest that terrestrial OM input could play a more pivotal role in trace metal processing in coastal environments than hitherto acknowledged.
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23687. 题目: Anomalous δ13C in particulate organic carbon at the chemoautotrophy maximum in the Cariaco Basin
文章编号: N20020113
期刊: Journal of Geophysical Research: Biogeosciences
作者: Mary I. Scranton, Gordon T. Taylor, Robert C. Thunell, Frank E. Muller‐Karger, Yrene Astor, Peter Swart, Virginia P. Edgcomb, Maria G. Pachiadaki
更新时间: 2020-02-01
摘要: A chemoautotrophy maximum is present in many anoxic basins at the sulfidic layer's upper boundary, but the factors controlling this feature are poorly understood. In 13 of 31 cruises to the Cariaco Basin, particulate organic carbon (POC) was enriched in ¹³C (δ¹³C_POC as high as ‐16‰) within the oxic/sulfidic transition compared to photic zone values (‐23 to ‐26‰). During “heavy” cruises, fluxes of O₂ and [NO₃^‐ + NO₂^‐] to the oxic/sulfidic interface were significantly lower than during “light” cruises. Cruises with isotopically heavy POC were more common between 2013 and 2015 when suspended particles below the photic zone tended to be nitrogen‐rich compared to later cruises. Within the chemoautotrophic layer, nitrogen‐rich particles (molar ratio C/N< 10) were more likely to be ¹³C‐enriched than nitrogen‐poor particles, implying these inventories were dominated by living cells and fresh detritus rather than laterally transported or extensively decomposed detritus. During “heavy” cruises, ¹³C enrichments persisted to 1300 m, providing the first evidence of downward transport of chemoautotrophically‐produced POC. Dissolved inorganic carbon assimilation during “heavy” cruises (n = 3) was faster and occurred deeper than during “light” cruises (n = 2). Metagenomics data from the chemoautotrophic layer during two cruises support prevalence of microorganisms carrying RuBisCO form II genes, which encode a carbon fixation enzyme that discriminates less against heavy isotopes than most other carbon fixation enzymes, and metatranscriptomics data indicate that higher expression of form II RuBisCO genes during the “heavy” cruises at depths where essential reactants coexist is responsible for the isotopically heavier POC.

23688. 题目: Shale as a Source of Organic Carbon in Floodplain Sediments of a Mountainous Watershed
文章编号: N20020112
期刊: Journal of Geophysical Research: Biogeosciences
作者: Patricia M. Fox, Markus Bill, Katherine Heckman, Mark Conrad, Carolyn Anderson, Marco Keiluweit, Peter S. Nico
更新时间: 2020-02-01
摘要: Shales contain high levels of organic carbon (OC) and represent a large fraction of the earth's reduced carbon stocks. While recent evidence suggests that shale‐derived OC may be actively cycled in riverine systems, this process is poorly understood and not currently considered in global C models. Through the use of sediment density fractionations, extractions, radiocarbon measurements, and chemical characterization, we provide information on the abundance, chemistry, and mobility of shale‐derived OC in floodplain sediments of a shale‐rich mountainous watershed. The heavy fraction (HF) of the sediment, representing mineral‐associated OC, is the largest (84 ± 6% of TOC) and oldest (Δ¹⁴C values ‐224 to ‐853‰) OC pool. Evidence of shale‐derived OC is observed in all sediment C pools (i.e., occluded light fraction, water‐soluble, and pyrophosphate‐extractable) except the free light fraction, which is entirely modern. Relatively consistent chemistry was observed across samples for extracted and density‐separated OC, despite wide ranges of Δ ¹⁴C values. Carbon spectroscopy revealed that floodplain sediments had a higher degree of functionalized aromatic groups and lower carbonate content compared to shale collected nearby, consistent with chemical alteration and mixing with other C sources in the floodplain. We estimate approximately 23‐34% of sediment OC is derived from shale, with implications for other shale‐derived elements (e.g., N). This study demonstrates the important contribution of shale‐OC, particularly in environments with low litter inputs. The large impact of radiocarbon‐dead shale‐OC, which has a thermally altered chemical structure distinct from plant litter, on Δ ¹⁴C values and reactivity of sediment‐OC must be considered.

23689. 题目: Tracing sources of natural organic matter, trihalomethanes and metals in groundwater from a karst region
文章编号: N20020111
期刊: Environmental Science and Pollution Research
作者: Connie O’Driscoll, Eoin McGillicuddy, Peter Croot, Pamela Bartley, John McMyler, Jerome Sheahan, Liam Morrison
更新时间: 2020-02-01
摘要: Groundwater offers an important source for drinking water around the world; however, groundwater quality is under increasing pressure and is particularly vulnerable in karst areas. Total organic carbon (TOC) is significantly related to groundwater quality and when not removed by water treatment processes can give rise to the formation of disinfection by-products trihalomethanes (THMs) above the level of compliance. This study investigated the source of organic matter giving rise to the THM exceedances in a groundwater supply in a karst area. Results highlighted that source water for this groundwater supply was prone to surface water infiltration linked to rainfall events; was not accurately captured in the zone of contribution (ZoC); had inadequate treatment of natural organic matter (NOM) and suffered THM exceedances in 45% of sampling events. THMs were mostly represented by chloroform and caused by terrestrial delivered reprocessed organic matter. This work will support water managers tasked with decision-making.

23690. 题目: Biochar exerts negative effects on soil fauna across multiple trophic levels in a cultivated acidic soil
文章编号: N20020110
期刊: Biology and Fertility of Soils
作者: Ting Liu, Lihua Yang, Zhengkun Hu, Jingrong Xue, Yanyan Lu, Xiaoyun Chen, Bryan S. Griffiths, Joann K. Whalen, Manqiang Liu
更新时间: 2020-02-01
摘要: Biochar application is perceived as a promising agricultural technology, but risk evaluation on the soil ecosystem has focused exclusively on soil microbes, whether microfood-web is likewise influenced by biochar remains unclear. We carried out a pot experiment planted with rapeseed for 2 years to test how biochar application (0, 20, 60 t ha⁻¹), with or without nitrogen (N) fertilizer (0, 60, 120 t ha⁻¹), affected soil microbes and microfauna (protists and nematodes). We observed that a high amount of biochar (60 t ha⁻¹) increased crop productivity, microbial activity, and biomass carbon (C) and N, as well as the abundance of flagellates (protists), but decreased the abundances of bacterivorous, fungivorous, and herbivorous nematodes as well as the abundance of amoebae (protists). High biochar addition rates also shifted nematode community composition toward a fungivore dominance, and favored herbivores by decreasing the ratio of microbivorous to herbivorous nematodes. However, N fertilizer and its interaction with biochar generally had no effect on microbial activity and biomass as well as the abundance of protist and nematode. A structural equation model revealed that the effects of biochar on soil biota were largely direct, which might depend on biochar properties (e.g., pore size and alkalinity), whereas indirect effects, mediated by crop, soil pH, soil moisture, and polycyclic aromatic hydrocarbon (PAH) concentration, generally had no effect on soil biota. We conclude that biochar is a suitable soil amendment for increasing crop growth, but its detrimental effect on multitrophic levels of soil fauna calls for an identification of the optimal application rate and size fraction that could minimize potential negative effects on certain soil communities.

23691. 题目: Comparison of soil microbial community between planted woodland and natural grass vegetation on the Loess Plateau
文章编号: N20020109
期刊: Forest Ecology and Management
作者: Yang Yang, Huan Cheng, Liangxu Liu, Yanxing Dou, Shaoshan An
更新时间: 2020-02-01
摘要: Soil microorganisms play an important role in regulating subsurface ecological processes. Planted woodland and natural grass vegetation are the main vegetation restoration strategies for preventing soil erosion on the Loess Plateau of China. However, the response of soil microbial community and diversity to planted woodland and natural grass vegetation is largely unknown in this region. Here, we investigated soil microbial community and diversity using high-throughput sequencing approaches in planted woodland and natural grass vegetation. We found a disproportionate influence of planted woodland and natural grass vegetation on soil microbial diversity, and there was an increase of soil fungal diversity and a decrease of soil bacterial diversity in planted woodland. Both soil pH and soil organic carbon (SOC) were highly related to soil microbial diversity in planted woodland and natural grass vegetation. Moreover, we found the complex interaction networks of soil fungal community in planted woodland. Meanwhile, there were the higher total path coefficients of soil fungal diversity and the lower total path coefficients of bacterial diversity in planted woodland according to SEM (structural equation modeling). Besides, planted woodland explained more variation to soil fungal diversity and natural grass vegetation explained more variation to soil bacterial diversity, indicating that soil fungal diversity was more easily affected by planted woodland, while soil bacterial diversity was more easily affected by natural grass vegetation. To enhance the balance of soil microbial diversity, we suggested that both planted woodland and natural grass vegetation are needed in this region, highlighting the necessity of understanding soil microbial ecology to manage vegetation restoration on the Loess Plateau of China.

23692. 题目: Adsorption and reduction of Cr(VI) by hydroxylated multiwalled carbon nanotubes: effects of humic acid and surfactants
文章编号: N20020108
期刊: Environmental Science and Pollution Research
作者: Yu Huang, Ke Song, Wei Luo, Jiewen Yang
更新时间: 2020-02-01
摘要: The present study investigated the impacts of humic acid (HA) and surfactants (SDBS and CTAB), which were ubiquitously found in the aquatic environments, on the removal of Cr(VI) by the hydroxylated MWCNTs-OH. The results showed that MWCNTs-OH could remove Cr(VI) from aqueous solution via adsorption coupled with reduction, and the kinetics followed the pseudo-first-order model with the rate of 3.5 × 10⁻³ h⁻¹. In the presence of anionic SDBS, the removal percentage of Cr(VI) was greatly inhibited because the hydrophobic interaction and π-π interaction between SDBS and MWCNTs-OH surfaces not only decreased the adsorption sites for Cr(VI) but also made the surfaces more negatively charged. On the contrary, the existence of cationic CTAB could lead to the surfaces more positively charged, which consequently enhance the electrostatic attraction between Cr(VI) and the surfaces as well as the removal of Cr(VI). Noticeably, the presence of HA could promote the removal of Cr(VI), which was attributed to the reduction of Cr(VI) by the adsorbed HA. The ESR spectra indicated the existence of π-type radicals in HA structure and conduction electrons in MWCNTs-OH, and then the π-π interaction between MWCNTs-OH and adsorbed HA possibly increase the electron-donating ability of HA. Moreover, the promotive effect of HA could be enhanced with the addition of Ca²⁺. This study was helpful for us to understand the role of MWCNTs-OH in controlling the fate of Cr(VI) when HA and surfactants were present.

23693. 题目: Rhizobium improves nutritive suitability and tolerance of Phaseolus vulgaris to Colletotrichum lindemuthianum by boosting organic nitrogen content
文章编号: N20020107
期刊: Applied Soil Ecology
作者: Edwin M. Karoney, Dennis M.W. Ochieno, Danstone L. Baraza, Edward K. Muge, Evans N. Nyaboga, Victoria Naluyange
更新时间: 2020-02-01
摘要: Symbiotic nitrogen fixing Rhizobium species have been reported to trigger induced resistance reactions that are inhibitive to aboveground antagonists. We tested the hypothesis that root infection by nitrogen-fixing Rhizobium triggers enzyme-mediated induced resistance reactions, which lead to the production of defensive compounds that suppress aboveground colonization by foliar pests. An experiment was conducted using common bean Phaseolus vulgaris, comprising of factorial treatments of Rhizobium inoculation (with or without), C. lindemuthianum (with or without) and soil type (solarized and non-solarized). Anthracnose disease incidence was higher in plants under dual inoculation with C. lindemuthianum and Rhizobium than in plants inoculated with C. lindemuthianum alone (p < 0.05). Concentrations of N-based compounds in the form of total protein and the enzymes, peroxidase, ascorbate peroxidase and lipid peroxidase were higher in rhizobial plants, while that of catalase enzyme and the C-based compounds namely flavonoids, tannins and phenols were lower. Plant size and growth duration were not different between the treatments (p > 0.05). Soil pH, organic carbon and the concentration of nutrients (N, P, Na, Ca, Mg, Zn, Cu) in solarized soil were higher than in non-solarized soil, while Fe and K were lower. There was no evidence to support induced resistance since anthracnose disease was high in Rhizobium inoculated plants. High disease incidence without reduction in plant growth can be interpreted as host plant tolerance. In conclusion, Rhizobium infection of common bean enhances the production of N-based nutritive compounds, while limiting the production of C-based organic compounds associated with plant resistance, thereby promoting host plant suitability to C. lindemuthianum, and possibly enhancing host plant tolerance to the pathogen.

23694. 题目: Visualizing electron storage capacity distribution in biochar through silver tagging
文章编号: N20020106
期刊: Chemosphere
作者: Danhui Xin, Thomas Barkley, Pei C. Chiu
更新时间: 2020-02-01
摘要: Electron storage capacity (ESC) is the capacity of a black carbon to store and reversibly donate and accept electrons in redox processes. Electrochemical and chemical analyses have shown the ESC of black carbon (e.g., plant-based biochars) was on the order of a few mmol/g. However, it remains unknown where ESC is located. The spatial distribution of ESC is important because it controls the bioaccessibility of ESC and the rates of biochar redox reactions. Here we used silver to tag the ESC of a wood-derived biochar. Ag⁺ was allowed to diffuse into the pores of reduced biochar at a constant pH. Up to 2.49 mmol Ag⁺/g biochar (corresponding to 62% of its ESC) was reduced to Ag^o nanoparticles (nAg), which served as an ESC marker and was visualized by electron microscopy. Abundant and dense nAg were observed on the biochar surface. In addition, microtomed samples showed ubiquitous and well-dispersed nAg in the interior of biochar, which explains pore diffusion-limited redox reactions and the partial bioaccessibility of its ESC. In addition to probing ESC distribution in black carbon, this method represents a new, ESC-based approach to incorporate large quantities of Ag and other redox-active elements into carbon media for potential environmental applications.
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23695. 题目: Effects of nano-Fe₃O₄-modified biochar on iron plaque formation and Cd accumulation in rice (Oryza sativa L.)
文章编号: N20020105
期刊: Environmental Pollution
作者: Jing-Yi Zhang, Hang Zhou, Jiao-Feng Gu, Fang Huang, Wen-Jun Yang, Shi-Long Wang, Teng-Yue Yuan, Bo-Han Liao
更新时间: 2020-02-01
摘要: Nano-Fe₃O₄-modified biochar (BC–Fe) was prepared by the coprecipitation of nano-Fe₃O₄ on a rice husk biochar surface. The effects of BC-Fe on cadmium (Cd) bioavailability in soil and on Cd accumulation and translocation in rice (Oryza sativa L. cv. ‘H You 518’) were investigated in a pot experiment with 7 application rates (0.05–1.6%, w/w). BC-Fe increased the biomass of the rice plants except for the roots and affected the concentration and accumulation of Cd and Fe in the plants. The Cd concentrations of brown rice were significantly decreased by 48.9%, 35.6%, and 46.5% by the 0.05%, 0.2%, and 0.4% BC-Fe treatments, respectively. Soil cation exchange capacity (CEC) increased by 9.4%–164.1% in response to the application of BC-Fe (0.05–1.6%), while the soil Cd availability decreased by 6.81%–25.0%. However, 0.8–1.6% BC-Fe treatments promoted Cd transport to leaves, which could increase the risk of Cd accumulation in brown rice. Furthermore, BC-Fe application promoted the formation of iron plaque and enhanced the root interception of Cd. The formation of iron plaque reduced the toxicity of Cd to rice roots, but this barrier effect was limited and had an interval threshold (DCB-Fe: 22.5–27.3 g·kg⁻¹) under BC-Fe treatments.
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23696. 题目: Importance of the structure and micropores of sedimentary organic matter in the sorption of phenanthrene and nonylphenol
文章编号: N20020104
期刊: Environmental Pollution
作者: Decheng Xu, Shujie Hu, Yongqiang Xiong, Yu Yang, Yong Ran
更新时间: 2020-02-01
摘要: The demineralized fraction (DM), lipid-free fraction (LF), nonhydrolyzable organic carbon fraction (NHC), and black carbon (BC) were isolated from five marine surface sediments, and they were characterized by elemental analysis as well as CO₂ and N₂ adsorption techniques, respectively. The NHC fractions were characterized using advanced solid-state ¹³C nuclear magnetic resonance (NMR) and x-ray photoelectron spectroscopy (XPS). Then, the sorption isotherms of phenanthrene (Phen) and nonylphenol (NP) on all of the samples were investigated by a batch technique. The CO₂ micropore volumes were corrected for the outer specific surface areas (SSAs) by using the N₂-SSA. Significant correlations between the micropore-filling volumes of Phen and NP and the micropore volumes suggested that the micropore-filling mechanism dominated the Phen and NP sorption. Meanwhile, the (O + N)/C atomic ratios were negatively and significantly correlated with the sorption capacities of Phen and NP, indicating that the sedimentary organic matter (SOM) polarity also played a significant role in the sorption process. In addition, a strong linear correlation was demonstrated between the aromatic C and the sorption capacity of Phen for the NHC fractions. This study demonstrates the importance of the micropores, polarity, and aromaticity on the sorption processes of Phen and NP in the sediments.
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23697. 题目: Time-dependent evolution of Zn(II) fractions in soils remediated by wheat straw biochar
文章编号: N20020103
期刊: Science of The Total Environment
作者: Ping Wu, Ting-Ting Qian, Ting-Ting Fan, Ying Zhang, Cun Liu, Dong-Mei Zhou, Yu-Jun Wang
更新时间: 2020-02-01
摘要: Biochar is a cost-effective and multifunctional carbon material, which can be used to immobilize heavy metal (HM) in soil. To date, the immobilization of different HM by various biochars are well-studied, however, little is known about the release condition of the immobilized HM. As the released HM may bring a threat to the soil environment, it is critical to understand the release pattern of biochar-sorbed HM in soil. Herein, six wheat straw-derived biochars (WBs) pyrolyzed under different temperature and duration time were loaded with zinc(Zn (II)), and the evolution of Zn(II) fractions in soils remediated by WBs over time was investigated by Community Bureau of Reference (BCR) three-step sequential extraction method. The main Zn(II) species sorbed on WBs were the Zn(II) sorbed on the acidic functional groups of WB and that sorbed on WB surface via electrostatic interaction. Generally, Zn(II) sorbed on high-temperature WB was more mobile than that sorbed on low-temperature WB. In the red soil, the soluble and exchangeable Zn(II) (i.e., Zn(II) in Fraction 1) in WB was inclined to transform to organic matter associated-Zn(II) (i.e., Zn(II) in Fraction 3) and residual Zn(II) (i.e., Zn(II) in Fraction 4). In the yellow-brown soil, the soluble and exchangeable Zn(II) in WB was prone to convert into amorphous Fe/Mn oxide associated-Zn(II) (i.e., Zn(II) in Fraction 2) and residual Zn(II). These results imply that Zn(II) sorbed by WB has the risk to be released into the soil environment, and WB produced at low temperature are more suitable to remediate soils with low/neutral pH.
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23698. 题目: Electromagnetic fields for biofouling mitigation in reclaimed water distribution systems
文章编号: N20020102
期刊: Water Research
作者: Yang Xiao, Youngwoo Seo, Yufei Lin, Lei Li, Tahir Muhammad, Changjian Ma, Yunkai Li
更新时间: 2020-02-01
摘要: Biofouling is ubiquitous in reclaimed water distribution systems and causes various industrial, economical, and health issues. This paper investigated the anti-biofouling efficacy of electromagnetic fields (EMFs) for agricultural emitters used for two types of reclaimed water. 16S rRNA gene sequencing and X-ray diffraction were applied to determine the microbial communities and mineral compositions in biofilm. The obtained results revealed that EMF treatment significantly changed the bacterial communities and reduced their diversities in biofilm by affecting water quality parameters. Network analysis results indicated that EMFs were detrimental to the co-occurrence patterns of mutualistic relationships among bacterial species, destroyed the connectivity and complexity of the networks, and inhibited biofilm formation [decreased total biomass and extracellular polymeric substance (EPS) content]. EMF treatment could also decrease the deposition of mineral precipitates, reducing the carbonate and silicate content in biofilm. The decrease of EPS content appeared to reduce biofilm-induced mineral crystallization, while the ion precipitations accelerated by EMFs caused an erosive effect on biofilm. The results demonstrated that EMF treatment is an effective, chemical-free, and anti-biofouling treatment method with great potential for biofouling control in reclaimed water distribution systems.
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23699. 题目: Mitigation of methylmercury production in eutrophic waters by interfacial oxygen nanobubbles
文章编号: N20020101
期刊: Water Research
作者: Xiaonan Ji, Chengbin Liu, Meiyi Zhang, Yongguang Yin, Gang Pan
更新时间: 2020-02-01
摘要: In mercury (Hg)-polluted eutrophic waters, algal blooms are likely to aggravate methylmercury (MeHg) production by causing intensified hypoxia and enriching organic matter at the sediment-water interface. The technology of interfacial oxygen (O₂) nanobubbles is proven to alleviate hypoxia and may have potential to mitigate the risks of MeHg formation. In this study, incubation column experiments were performed using sediment and overlying water samples collected from the Baihua Reservoir (China), which is currently suffering from co-contamination of Hg and eutrophication. The results indicated that after the application of O₂ nanobubbles, the %MeHg (ratio of MeHg to total Hg) in the overlying water and surface sediment decreased by up to 76% and 56% respectively. In addition, the MeHg concentrations decreased from 0.54 ± 0.15 to 0.17 ± 0.01 ng L⁻¹ in the overlying water and from 56.61 ± 9.23 to 25.48 ± 4.08 ng g⁻¹ in the surface sediment. The decline could be attributed to the alleviation of anoxia and the decrease of labile organic matter and bioavailable Hg. In addition, hgcA gene abundances in the overlying water and surface sediment decreased by up to 69% and 44% after the addition of O₂ nanobubbles, as is consistent with MeHg occurrence in such areas. Accordingly, this work proposed a promising strategy of using interfacial oxygen nanobubbles to alleviate the potentially enhanced MeHg production during algal bloom outbreaks in Hg-polluted eutrophic waters.
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23700. 题目: Effect of Chloride and Suwannee River Fulvic Acid on Cu Speciation: Implications to Cu Redox Transformations in Simulated Natural Waters
文章编号: N20013119
期刊: Environmental Science & Technology
作者: Guowei Xing, Shikha Garg, Christopher J. Miller, A. Ninh Pham, T. David Waite
更新时间: 2020-01-31
摘要: Copper is a critical trace nutrient and, at higher concentrations, a toxicant in natural waters, with the relative rates of transformation between the Cu(I) and Cu(II) oxidation states being key to its speciation, bioavailability, and toxicity. While the influence of chloride (Cl−) and natural organic matter on Cu speciation and associated redox transformations has been studied separately, their combined influence on Cu speciation and Cu redox transformations has not been examined. As such, in this study, we investigate the impact of Cl– and Suwannee River fulvic acid (SRFA) on Cu(II) reduction and Cu(I) oxidation kinetics at pH 8.2. SRFA plays a dual role in providing Cu(II) reducing moieties as well as Cu ligating sites. Our results indicate that the SRFA-bound Cu(II) is less reactive than the inorganic Cu(II), and the SRFA-bound Cu(I) being much more rapidly oxidized than the inorganic Cu(I). The presence of Cl– weakens Cu(II) binding by SRFA, thereby increasing the reactivity of Cu(II). Similarly, weakening of Cu(I) binding by SRFA and concomitant binding of Cu(I) by Cl– stabilizes Cu(I). Our results further show that continuous formation of hydrogen peroxide occurs in the presence of Cu(II), SRFA, and Cl– in air-saturated solution with the presence of H2O2 enhancing the dynamic nature of the system.