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101. 题目: Treatment of the saline-alkali soil with acidic corn stalk biochar and its effect on the sorghum yield in western Songnen Plain
文章编号: N21072327
期刊: Science of The Total Environment
作者: Zhengxin Zhou, Zhiyong Li, Zhenqian Zhang, Liru You, Lifeng Xu, Hongyan Huang, Xueping Wang, Yan Gao, Xuejun Cui
更新时间: 2021-07-23
摘要: Due to biochar could improve the physical and chemical properties of soil and promote crop growth, it is widely used in soil remediation, especially in saline soil. However, it is rarely studied of the application of acidic biochar in saline-alkali land. A field experiment with acidic corn stalk biochar (ACSBC) as a soil amendment was carried out in the western Songnen Plain of China. ACSBC (0, 0.15, 0.3, 0.45, 0.6, 0.75, 1, 6 and 15 t ha−1) was added to the topsoil to evaluate the combined effects on soil and sorghum yield. During the seeding and harvest period, the content of soil water, nutrient elements, cation exchange capacity (CEC), organic matter (OM), soluble cations (K+, Ca2+, Mg2+) increased, Na+ content showed opposite trend. However, soil pH decreased averagely with 0.3 and 1.0 during the seeding and harvest period respectively, salinity decreased with 19.37% and 18.14%, exchange sodium percentage (ESP) decreased with 37.08% and 37.04%. The sorghum yield increased 32.98% averagely, significantly by 51.37% and 47.33% with the 0.6 and 1 t ha−1 of ACSBC treatments respectively. These experimental results show that proper application of ACSBC in saline-alkali soil can effectively improve soil properties and increase sorghum yield.

102. 题目: Relationships between the Physicochemical Properties of Dissolved Organic Matter and Its Reaction with Sodium Borohydride
文章编号: N21072326
期刊: Environmental Science & Technology
作者: Hang Li, Garrett McKay
更新时间: 2021-07-23
摘要: The reaction of dissolved organic matter (DOM) with sodium borohydride has been used to understand the geographic origin of DOM and investigate the photophysical model underlying DOM’s optical properties. However, the physicochemical properties of DOM (e.g., molecular size and charge) that influence the kinetics and ultimate reducibility of DOM by borohydride remain poorly characterized. Herein, we studied the kinetics of DOM-borohydride reactions by recording absorbance and fluorescence spectra at a high temporal frequency (every ∼10 min for 24 h) for a diverse set of DOM isolates of aquatic and soil origin. The reducibility of DOM by sodium borohydride (as judged by relative removal of initial absorbance) varied appreciably among the DOM samples studied, with soil humic substances being less reducible than aquatic humic substances and natural organic matter. While statistically significant correlations were found between the reducibility of DOM and descriptors of molecular size, these descriptors were not able to differentiate the reducibility of soil versus aquatic DOM isolates that had similar bulk properties. Thus, it appears that the extent of absorbance removal by borohydride is largely driven by the origin of the humic substance isolate (aquatic vs soil) instead of molecular size or charge. Borohydride reduction resulted in increased fluorescence emission across UV and visible excitation wavelengths. However, the enhanced emission at visible excitation decreased over a time period of hours to days, suggesting that reduction of an important subset of DOM chromophores is reversible. This reversibility in fluorescence emission is consistent with the small role of quinones in the absorbance of DOM but suggests a more important role for quinone-containing charge-transfer contacts in the fluorescence of DOM, particularly at visible excitation wavelengths.

103. 题目: Resistance genes and extracellular proteins relieve antibiotic stress on the anammox process
文章编号: N21072325
期刊: Water Research
作者: Nian-Si Fan, Jin-Jin Fu, Dong-Qi Huang, Yuan-Long Ma, Zheng-Yang Lu, Ren-Cun Jin, Ping Zheng
更新时间: 2021-07-23
摘要: The anaerobic ammonium oxidation (anammox) process is regarded as a promising approach to treat antibiotic-containing wastewater. Therefore, it is urgent to elucidate the effects of various antibiotics on the anammox process. Moreover, the mechanism of extracellular polymeric substance (EPS) as protective barriers to relieve antibiotic stress remain unclear. Therefore, the single and combined effects of erythromycin (ETC) and sulfamethoxazole (SMZ), and interactions between EPS and antibiotics were investigated in this study. Based on a 228-day continuous flow experiment, high concentrations of ETC and SMZ had significant inhibitory effects on the nitrogen removal performance of the anammox process, with the abundances of corresponding antibiotic resistance genes (ARGs) increasing. In addition, the combined inhibitory effect of the two antibiotics on the anammox process was more significant and longer-lasting than that of the single. However, the anammox process was able to quickly recover from deterioration. The tolerance of anammox granules to the stress of low-concentration antibiotics was probably attributed to the increase in ARGs and secretion of EPS. Molecular docking simulation results showed that proteins in EPS could directly bind with SMZ and ETC at the sites of GLU-307, HYS-191, ASP-318 and THR-32, respectively. These findings improved our understanding of various antibiotic effects on the anammox process and the interaction mechanism between antibiotics and proteins in EPS.

104. 题目: Mercury adsorption kinetics on sulfurized biochar and solid-phase digestion using aqua regia: A synchrotron-based study
文章编号: N21072324
期刊: Chemical Engineering Journal
作者: Jinping Tang, Carol J. Ptacek, David W. Blowes, YingYing Liu, Yu Feng, Y. Zou Finfrock, Peng Liu
更新时间: 2021-07-23
摘要: Various studies have focused on the performance and removal mechanism of aqueous Hg using biochars, but the specific Hg removal process has not been fully elucidated. Aqua regia digestion is considered a common Hg extraction method from solid samples, but uncertainties exist regarding Hg extraction from biochars. Aqueous Hg removal kinetic experiments followed by aqua regia digestion procedures and solid-phase analyses were conducted to investigate the Hg diffusion and transformation processes on oak biochar (BC) and evaluate the extraction efficiency of aqua regia as well as the stability of Hg adsorbed by biochars. Kinetic experiments indicated Hg adsorption capacity increased and adsorption rate decreased using oak biochar pretreated with calcium polysulfide (CP-BC) relative to unmodified BC. Confocal micro-X-ray fluorescence imaging illustrated Hg penetration into the interior of BC and accumulation on the CP-BC surface. Hg extended X-ray absorption fine structure spectra modeling indicated the Hg was first adsorbed as Hg(II)–O and transformed to Hg(II)–S forms on CP-BC, whereas only the Hg(II)–Cl forms of Hg were observed on BC. The results of aqua regia digestion suggest that Hg cannot be completely extracted from BC. These results provide information on the kinetic processes of Hg removal by biochars and incomplete extraction of Hg by aqua regia, which is critical for optimizing biochar modification methods and evaluating the long-term stability of adsorbed Hg in aqueous environments.

105. 题目: Sediment methane production within eutrophic reservoirs: The importance of sedimenting organic matter
文章编号: N21072323
期刊: Science of The Total Environment
作者: Renata Gruca-Rokosz, Maksymilian Cieśla
更新时间: 2021-07-23
摘要: While temperate reservoirs can be a significant source of atmospheric methane (CH4), knowledge of the role they play in global emissions of the gas remains limited in line with extreme temporal and spatial variability noted both within and between reservoirs. There is also still no clear identification of the environmental factors influencing the emission of this gas to the atmosphere. This article presents the results of research into the influence of sedimenting matter on CH4 emission from the surface of different zones of reservoirs. The research were conducted in 2018-2019 within Maziarnia and Nielisz Reservoirs – two artificial bodies of water of eutrophic status both located in SE Poland. Their diffusive CH4 fluxes at the water-air interface were measured using the “static chamber” method, while sediment traps monitored the rate of accumulation of sedimenting matter in bottom sediments (US). The CH4 fluxes noted at the reservoirs proved highly variable, both temporally and spatially, ranging from 0.02 to over 2500 mmol/m2d. Determined accumulation indexes were in turn in the 13.61-618.49 g/m2·d range. Nevertheless, CH4 flux was found to correlate significantly with sedimentation index (US), with highest observed values for both reservoirs noted in river zone, while the lowest characterise the lacustrine zone. On this basis, it was hypothesised that sedimentation index may prove a useful tool in estimating CH4 emissions from reservoirs, with the reverse relationship also likely to apply. Furthermore, the key factor found to be responsible for the aforementioned temporal and spatial variations in CH4 emissions is primary production, whose subsequent sedimentation supplies sediments with easily-degradable organic matter. The results presented here contribute to an understanding of environmental factors that may influence spatial variation in CH4 production and can be useful to serve determinate of potential methods by which to reduce emissions this gas from managed systems such as reservoirs.

106. 题目: Hydrocarbon sedimentary organic matter composition from different water-type floodplain lakes in the Brazilian Amazon
文章编号: N21072322
期刊: Organic Geochemistry
作者: Alexander A. Lopes, Vinícius B. Pereira, Leonardo Amora-Nogueira, Humberto Marotta, Luciane S. Moreira, Renato C. Cordeiro, Gabriela Vanini, Débora A. Azevedo
更新时间: 2021-07-23
摘要: Amazon rivers and flooded areas can be categorized into three types of water: white, black, and clear. These categories present unique physical-chemical characteristics that influence the characteristics and distribution of sedimentary organic matter (SOM). A geochemical assessment of the short sedimentary cores of four floodplain lakes within the Brazilian Amazon basin was performed. Two black, one white, and one clear-water floodplain lakes were selected to evaluate the variability of OM composition based on aliphatic biomarker and carbon isotopic ratios, as proxies for an enhanced methane cycle, anoxia, and to determine the origin of predominant aliphatic biomass. Gas chromatography was coupled to flame ionization detection (GC-FID), mass spectrometry (GC–MS) and combustion-isotope ratio mass spectrometry (GC–C-IRMS). These were used to determine aliphatic biomarker ratios, for quantification, and to measure carbon isotopic compositions. The TOC content was inversely proportional to the expected OM productivity; one black water (low OM productivity) presented the highest TOC content, and white water (high productivity) presented the lowest. Also, clear water lake (intermediate productivity) presented TOC content between the other lakes. Based on n-alkane proxies and profiles, as well as bacterial and plant-derivative terpene distribution, we observed a mostly terrigenous contribution for the black and clear water lakes (allochthonous SOM), as well as a prevalence of aquatic organisms in white water lake (autochthonous SOM). Only in the most superficial section of the white water lake, was intense OM degradation substantiated with n-alkanes showing an even-short-chain predominance, indicative of OM cycling. Also, for one black water lake, we detected depleted n-alkane and diploptene δ13C values (–42‰) associated with methanotrophic archaea and higher relative concentrations of des-A-triterpenes commonly associated with anoxic sedimentation. Based on these data, the influence of water-type on the SOM composition was verified. The approach helps to understand the application of n-alkane proxies to differentiate Amazonian environments.

107. 题目: Adsorption behaviour and interaction of organic micropollutants with nano and microplastics – A review
文章编号: N21072321
期刊: Science of The Total Environment
作者: Yangmei Yu, Wing Yin Mo, Tero Luukkonen
更新时间: 2021-07-23
摘要: Nano/microplastics (NPs/MPs) and organic micropollutants are contaminants exerting serious threats to aquatic ecosystems, which are further aggravated through their interactions. Organic micropollutants can adsorb on the surface of NPs/MPs, enter to the digestive systems of aquatic organisms with NPs/MPs, and desorb from the surface inside the organism. Consequently, the migration behaviour of organic micropollutants is significantly affected increasing their risk to accumulate in the food chain. Therefore, understanding the adsorption interactions between NPs/MPs and organic micropollutants is critical for evaluating the fate and impact of NPs/MPs in the environment. This review article provides an overview about the role of NPs/MPs as (temporary) sinks for organic micropollutants but also as primary sources of organic micropollutants through the leaching of plastic additives. Specifically, the following aspects are discussed: adsorption/desorption mechanisms (e.g., hydrophobic partitioning interaction, surface adsorption by van der Waals forces or hydrogen bonding, and pore filling), influencing environmental factors (e.g., pH, salinity, dissolved organic matter), leaching of plastic additives from NPs/MPs, and potential ecotoxicological effects arising from the interactions of NPs/MPs and organic micropollutants.

108. 题目: Engineering conversion of Asteraceae plants into biochars for exploring potential applications: A review
文章编号: N21072320
期刊: Science of The Total Environment
作者: Duyen Thi Cam Nguyen, Hanh T.N. Le, Thuong Thi Nguyen, Thi Thanh Thuy Nguyen, Rock Keey Liew, Long Giang Bach, Trinh Duy Nguyen, Dai-Viet N. Vo, Thuan Van Tran
更新时间: 2021-07-23
摘要: Asteraceae presents one of the most globally prevalent, cultivated, and fundamental plant families. However, a large amount of agricultural wastes has been yearly released from Asteraceae crops, causing adverse impacts on the environment. The objective of this work is to have insights into their biomass potentials, and technical possibility of conversion into biochars. Physicochemical properties are systematically articulated to orientate environmental application, soil amendment, and other utilizations. Utilizations of Asteraceae biochars in wastewater treatment can be categorized by heavy metal ions, organic dyes, antibiotics, persistent organic pollutants (POPs), and explosive compounds. Some efforts were made to analyze the production cost, as well as the challenges and prospects of Asteraceae-based biochars.

109. 题目: Enhanced depletion of antibiotics and accelerated estabilization of dissolved organic matter by hydrothermal pretreatment during composting of oxytetracycline fermentation residue
文章编号: N21072319
期刊: Bioresource Technology
作者: Picheng Gong, Huiling Liu, Gang Wang, Jie Yao, Xiaohu Dai
更新时间: 2021-07-23
摘要: In this study, the feasibility of employing hydrothermal pretreatment (HTPT) to improve the composting of oxytetracycline fermentation residue (OFR) was evaluated by investigating the depletion of oxytetracycline (OTC) and evolution of dissolved organic matter (DOM). HTPT drastically declined the final content of OTC and its main transformation intermediates in OFR compost from 88.96 to 2.61 mg/kg. Although HTPT slightly increased the DOM content and significantly decreased the contents of biodegradable and humified compounds in OFR compost, it did not significantly change the germination index of OFR compost. Nevertheless, the time required for the overall pattern of DOM parameters to reach stabilization was shortened from 28 to 14 days by HTPT. Taken together, although HTPT did not change the maturity degree of OFR compost, it obviously shortened the OFR composting cycle and lowered the potential risk of OFR compost, confirming that HTPT could efficiently improve the OFR composting.

110. 题目: Co-pyrolysis of corn stover with industrial coal ash for in situ efficient remediation of heavy metals in multi-polluted soil
文章编号: N21072318
期刊: Environmental Pollution
作者: Yu Xia, Yi Li, Yuting Sun, Wei Miao, Zhengang Liu
更新时间: 2021-07-23
摘要: Coal ash incorporated biochar (CA/BC) composite was prepared by co-pyrolysis of agricultural residue and industrial coal ash and applied for remediation of soils polluted by lead (Pb) and cadmium (Cd). The results showed that immobilization efficiency of CA/BC for heavy metals (HMs) was significantly enhanced by 77.1 % (Pb) and 42.7 % (Cd) compared to pristine biochar (BC), and this was mainly due to the increased pH value, surface functionality and surface negative charge. By the introduction of 5 % CA/BC, the polluted soils showed the highest reduction of leaching toxicity by 67.9 % (Pb) and 49.7 % (Cd), respectively. The chemical speciation of Pb and Cd in soils was changed remarkably and the reduced bioavailable Pb and Cd were mainly transformed from acid-soluble fraction into the most stable form of residual fraction. The mechanism study showed that surface precipitation, complexation, cation exchange and cation-π interaction of CA/BC mainly contributed to heavy metals (HMs) immobilization. The pot experiments further confirmed that incorporation of 5 % CA/BC effectively reduced plant Pb and Cd accumulation by 81 % and 62.5 % respectively, and significantly promoted the plant growth of paddy rice by 3.1, 2.2 and 2.0 times in terms of root, stem length and dry mass parameters. The present study offered a cost-effective and green method to prepare soil amendment with great potential for remediation of soils polluted by HMs and realized the value-added utilization of waste agricultural residue and industrial coal ash.

111. 题目: Organic carbon modified Fe3O4/schwertmannite for heterogeneous Fenton reaction featuring synergistic in-situ H2O2 generation and activation
文章编号: N21072317
期刊: Separation and Purification Technology
作者: Ting Li, Zikai Wang, Zexin Zhang, Kun Feng, Jianru Liang, Dianzhan Wang, Lixiang Zhou
更新时间: 2021-07-23
摘要: Spontaneous generation of H2O2 and activation in heterogeneous Fenton is a promising technology for waste-water treatment. Here organic carbon modified Fe3O4/schwertmannite (Fe3O4/Sch/OC) by introducing Fe3O4 in the Acidithiobacillus ferrooxidans-driven Fe2+ oxidation process to give catalysts. In-situ H2O2 could be generated via Fe3O4/Sch/OC-driven oxygen reduction reaction (ORR), moreover, the in-situ H2O2 was disintegrated to produce •OH in Fe3O4/Sch/OC-driven Fenton reaction to degrade the methylene blue (MB). The catalysts were characterized by XRD, SEM, BET and XPS spectroscopy. Oxygen-containing functional groups (e.g., C=O, -COOH, -OH) on Fe3O4/Sch/OC surface could provide more active sites for the adsorption and reduction of O2. The carbon-modification promoted both the selectivity of 2e- ORR and Fe2+ content of catalyst. Thus, Fe3O4/Sch/OC exhibited a higher H2O2 selectivity (∼65%) and MB degradation efficiency (∼81%) than Sch, Fe3O4, or Fe3O4/Sch. In addition, in-situ H2O2 could be produced at a wide initial pH range (3 - 9). The degradation pathways of MB were also proposed based on theoretically calculated and LC-MS data. The finding opens up a new way for developing a cost-effective Sch-based catalyst for producing in-situ H2O2 and degrading pollutants.

112. 题目: Influence of sludge organic matter on elimination of polycyclic aromatic hydrocarbons (PAHs) from waste activated sludge by ozonation: Controversy over aromatic compounds
文章编号: N21072316
期刊: Science of The Total Environment
作者: Wenhao Li, Nanwen Zhu, Haiping Yuan, Yanwen Shen
更新时间: 2021-07-23
摘要: Ozonation has been widely used as a viable advanced oxidation process (AOP) for elimination of PAHs in waste activated sludge through effective sludge disintegration and abatement of organic pollutants. However, sludge organic matter (SOM) influences PAHs degradation during ozone treatment is still rarely understood. In this study, we investigated such an influence with the aid of solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and the corresponding two-dimensional correlation analysis (2D-COS) strategy. The results showed that the degradation of SOM macromolecules in the order of aromatic substances > aliphatic carbon > α carbon > amides groups > O-alkyl upon ozone treatment. Moreover, the PAHs removal efficiency was positively correlated with the aromaticity of sludge (R2 = 0.84–0.98), while negative associated with its aliphaticity (R2 = 0.81–0.95). Lastly, humic acid (HA) was used as a proxy of aromatic SOM to further explore their interaction with PAHs in sludge matrix. The results revealed that freely dissolved (HA-D) and suspended particulates (HA-S) imposed distinctively different influence on ozone-based PAHs degradation. The HA-S facilitated the elimination of PAHs by 7.95 ± 0.11%, while those HA-D reduced the removal efficiency by 16.70 ± 0.13%.

113. 题目: Photobleaching reduces the contribution of dissolved organic carbon to glacier melting in the Himalayas and the Tibetan Plateau
文章编号: N21072315
期刊: Science of The Total Environment
作者: Zhaofu Hu, Shichang Kang, Qingchai Chen, Jianzhong Xu, Chao Zhang, Xiaofei Li, Fangping Yan, Yulan Zhang, Pengfei Chen, Chaoliu Li
更新时间: 2021-07-23
摘要: Dissolved organic carbon (DOC) makes an important contribution to glacier melting in the Himalayas and the Tibetan Plateau (HTP). Photobleaching can effectively reduce the light absorption ability of DOC, further changing its impact on glacier melting, which is not yet well researched in the HTP. Therefore, snowpit samples from the Bayi, Ganglongjiama (GLJM), Jiemayangzong (JMYZ) and Demula (DML) glaciers were collected to study the influence of photobleaching on the light absorption ability of DOC and its impact on glacier melting. The results showed that the DOC concentration of snowpit samples, which was affected by the melting state and photobleaching, decreased from the northern HTP to the southern HTP. At an early stage of melting, the mass absorption cross-section value at 365 nm (MAC365) values showed a negative correlation with DOC concentrations in the snowpit at the JMYZ and DML glaciers, indicating that colored DOC tended to be concentrated in the snowpit during the melting process. With the aggravation of ablation, some snowpit samples in the GLJM and Bayi glaciers had both low concentrations and MAC365 values of DOC due to the reduced influence of photobleaching on the light absorption ability of DOC. Similarly, two fluorescence components (one protein-like component and one humic-like component) were identified in the extracted DOC at the JMYZ and DML glaciers, while those components were not detected in the GLJM glacier. Based on the sources of fluorescent DOC and five-day backward air mass trajectories, long-distance transport of pollutants from South Asia was an important source of snowpit DOC in the southern HTP. In this study, photobleaching can effectively remove colored and fluorescent DOC from snowpit samples in the HTP, further reducing the radiation forcing and glacier melting caused by DOC.

114. 题目: Transport process and source contribution of nitrogen in stormwater runoff from urban catchments
文章编号: N21072314
期刊: Environmental Pollution
作者: Yukun Ma, Shihui Wang, Xiaoyue Zhang, Zhenyao Shen
更新时间: 2021-07-23
摘要: Nitrogen in urban stormwater has been widely studied, and effective management of nitrogen pollution is critical for improving urban stormwater and receiving water quality. This requires an in-depth understanding of the transport process and source contribution to both dissolved and particulate nitrogen in stormwater from urban catchments. In this study, 123 stormwater runoff samples were collected from an urban catchment during different rainfall events. Dissolved and particulate nitrogen concentrations in roof runoff, road runoff, and sewer flow were analyzed. The concentration of dissolved nitrogen was higher in roof runoff than in road runoff and sewer flow. However, the concentration of particulate nitrogen was lower in roof runoff than in road runoff and sewer flow. Isotopic analysis and Bayesian mixing models showed that road runoff was the largest source contributor of both nitrate and particulate organic nitrogen (PON) in sewer flow discharged from the study catchment. In addition, road runoff contributed the majority of PON associated with coarse particles (>105 μm), whereas PON associated with fine particles (<105 μm) was primarily washed-off of sewer sediments. The results provided several suggestions for the management of nitrogen pollution in urban catchments. This study could help to fully understand the transport and sources of nitrogen pollution in urban stormwater and provide recommendations to the government for implementing appropriate stormwater management strategies to minimize stormwater pollution.

115. 题目: Prediction of hydrophobic organic compound partition to algal organic matter through the growth cycle of Microcystis aeruginosa
文章编号: N21072313
期刊: Environmental Pollution
作者: Peiyun Wei, Heyun Fu, Zhaoyi Xu, Dongqiang Zhu, Xiaolei Qu
更新时间: 2021-07-23
摘要: Algal organic matter (AOM) is an important source for the dissolved organic matter (DOM) pool in aquatic systems, particularly in eutrophic waters. In this study, we reported the dynamic pattern of AOM hydrophobicity during the growth cycle of Microcystis aeruginosa using the partition coefficients of AOM in the aqueous two-phase system (KATPS) as a simple quantitative measure. AOM hydrophobicity had significant and non-monotonic changes during the growth cycle. It increased in the lag and early exponential phases, then decreased in the late exponential and stationary phases, and rebounded in the decline phase. AOM hydrophobicity determined using the resin fractionation, SUVA254, and nuclear magnetic resonance methods shared similar non-monotonic pattern. Nevertheless, the correlations among these indicators were poor. The partition behavior of polycyclic aromatic hydrocarbons and chlorobenzenes to AOM was assessed based the KATPS dataset and the two-phase system (TPS) model. The TPS model showed good prediction power for the partition behavior of AOM with an RMSE of 0.23, suggesting that it was applicable to AOM from Microcystis aeruginosa. Our results indicate that algae activity will influence the overall hydrophobicity of the DOM pool depending on the growth phase, resulting in changes in the bioavailability of hydrophobic organic compounds in aquatic systems.

116. 题目: Organic Matter from Redoximorphic Soils Accelerates and Sustains Microbial Fe(III) Reduction
文章编号: N21072312
期刊: Environmental Science & Technology
作者: Andreas Fritzsche, Julian Bosch, Michael Sander, Christian Schröder, James M. Byrne, Thomas Ritschel, Prachi Joshi, Markus Maisch, Rainer U. Meckenstock, Andreas Kappler, Kai U. Totsche
更新时间: 2021-07-23
摘要: Microbial reduction of Fe(III) minerals is a prominent process in redoximorphic soils and is strongly affected by organic matter (OM). We herein determined the rate and extent of microbial reduction of ferrihydrite (Fh) with either adsorbed or coprecipitated OM by Geobacter sulfurreducens. We focused on OM-mediated effects on electron uptake and alterations in Fh crystallinity. The OM was obtained from anoxic soil columns (effluent OM, efOM) and included—unlike water-extractable OM—compounds released by microbial activity under anoxic conditions. We found that organic molecules in efOM had generally no or only very low electron-accepting capacity and were incorporated into the Fh aggregates when coprecipitated with Fh. Compared to OM-free Fh, adsorption of efOM to Fh decelerated the microbial Fe(III) reduction by passivating the Fh surface toward electron uptake. In contrast, coprecipitation of Fh with efOM accelerated the microbial reduction, likely because efOM disrupted the Fh structure, as noted by Mössbauer spectroscopy. Additionally, the adsorbed and coprecipitated efOM resulted in a more sustained Fe(III) reduction, potentially because efOM could have effectively scavenged biogenic Fe(II) and prevented the passivation of the Fh surface by the adsorbed Fe(II). Fe(III)–OM coprecipitates forming at anoxic–oxic interfaces are thus likely readily reducible by Fe(III)-reducing bacteria in redoximorphic soils.

117. 题目: Biochar and exogenous calcium assisted alleviation of Pb phytotoxicity in water spinach (Ipomoea aquatica Forsk) cultivated in Pb-spiked soil
文章编号: N21072311
期刊: Environmental Geochemistry and Health
作者: Shaojun Jiang, Yuehong Liu, Yuehong Shu
更新时间: 2021-07-23
摘要: The consumption of vegetables grown in Pb-polluted soils causes serious threats to human health around the globe. In this study, we evaluated the Pb toxicity alleviation in water spinach grown of pot experiments in Pb-spiked soil treated with biochar and exogenous calcium. The results showed that both biochar and exogenous calcium alleviated Pb stress in water spinach, which was mainly manifested on its improved soil health and increased growth and decreased Pb uptake. Incorporation of 3% biochar significantly reduced CaCl2 extracted Pb by 53.6% and decreased Pb accumulation in roots (67.1%) and shoots (80.8%). Our also findings indicated that Pb detoxification mechanism of biochar and exogenous calcium was totally different, while they can induce a synergistic impact on water spinach Pb stress alleviation. The combination of biochar and exogenous calcium in Pb-contaminated soil remediation may complement each other and reduce Pb entry into the human body through vegetables.

118. 题目: Distribution of persistent free radicals in different molecular weight fractions from peat humic acids and their impact in reducing goethite
文章编号: N21072310
期刊: Science of The Total Environment
作者: Yafang Shi, Chi Zhang, Jinbo Liu, Qingyang Dai, Yuanren Jiang, Mengning Xi, Hanzhong Jia
更新时间: 2021-07-23
摘要: Humic substances, the most abundant component of soil organic matter, play vital roles in the biogeochemical cycles and pollutant redox reactions. However, the knowledge regarding the distribution of persistent free radicals (PFRs) and redox capacity in different molecular weight fractions (MWF) of humic acid (HA) and their impact on the transformation of iron oxide minerals remains unknown. In this study, we separated bulk HA into various MWF using dialysis methods and systematically investigated their PFRs properties, redox capacity, and the impact in reducing goethite. The results showed that the PFRs in the low MWF (<3500, <7000, and <14,000 Da) can be assigned to oxygen-centered organic radicals while those in the bulk and high MWF (14000-retentate) were assigned to carbon-centered organic radicals. The PFRs concentrations of low MWF were 0.20–0.45 × 1016 spins/g, far less than those of bulk HA (3.04 × 1016 spins/g) and 14000-retentate (1.30 × 1016 spins/g). The total concentrations of reactive oxygen species (ROS) induced by PFRs in HA fractions ranged from 8.04 × 1016 (in 14000-retentate) to 32.35 × 1016 spins/g (in bulk HA). Compared with the low MWF, the 14000-retentate fractions had the higher reducing capacity, which was positively related to the content of PFRs and phenolic hydroxyl in HA. The results obtained provide valuable insight into the geochemistry processes of Fe-containing minerals during their interaction with HA in the natural environment. Overall, the results obtained provide valuable insight into the geochemical behaviors of HA-associated PFRs under natural conditions.

119. 题目: Particle‐Specific Toxicity of Copper Nanoparticles to Soybean ( Glycine max L.): Effects of Nanoparticle Concentration and Natural Organic Matter
文章编号: N21072309
期刊: Environmental Toxicology and Chemistry
作者: Yinlong Xiao, Wei Tang, Willie J. G. M. Peijnenburg
更新时间: 2021-07-23
摘要: For the soluble metallic nanoparticles (NPs), which forms (particles (NP(particle)) versus dissolved ions (NP(ion))) are the main cause of toxicity of the NP suspension (NP(total)) remains uncertain. In this study, soybean was exposed to Cu NPs in a hydroponic system to determine how natural organic matter (NOM, 10 mg/L) and concentration of Cu NP(total) (2-50 mg/L) affect the relative contributions of Cu NP(particle) and Cu NP(ion) to the overall toxicity. We found that NOM mitigated the phytotoxicity of Cu NP(particle) more significantly than that of Cu-salt. When no NOM was added, Cu NP(particle) rather than Cu NP(ion) were the main contributor to the observed toxicity regardless of the concentration of Cu NP(total). However, NOM tended to reduce the relative contribution of Cu NP(particle) to the toxicity of Cu NP(total). Especially at a low concentration of Cu NP(total) (2 mg/L), the toxicity of Cu NP(total) mainly resulted from Cu NP(ion) in the presence of NOM (accounting for ≥ 70% of the overall toxicity). This might be due to the combined effects of increased dissolution of Cu NPs and steric-electrostatic hindrance between Cu NP(particle) and the soybean roots caused by NOM. Fulvic acids (FAs) tended to reduce the role of Cu NP(particle) in the overall toxicity more effectively than humic acids (HAs), which might partially be due to the higher extent of Cu NP dissolution upon FA treatment than in case of HA treatment. Our results suggest that due to the relatively low metallic NP concentration and the presence of NOM in natural water NP(ion) are likely problematic, which can inform management and mitigation actions.

120. 题目: Tracing dissolved organic matter in inflowing rivers of Nansi Lake as a storage reservoir: Implications for water-quality control
文章编号: N21072308
期刊: Chemosphere
作者: Likui Feng, Jian Zhang, Jinlin Fan, Liangliang Wei, Shufei He, Haiming Wu
更新时间: 2021-07-23
摘要: Quantitative characterization of dissolved organic matter (DOM) in various aquatic ecosystems has become of increasing importance as its transformation plays a key role in inland water carbon, yet few studies have quantified water DOM inputs to storage lakes for water quality control and safety assurance. This study assessed the quantity and quality of DOM in 21 inflow rivers of Nansi Lake as the important storage lake of large-scale water transfer projects by using excitation-emission matrix spectroscopy coupled with parallel factor analysis (EEM-PARAFAC) and ultraviolet–visible (UV–Vis) spectroscopy. The results showed that DOM contents varied significantly with an average value of 5.8 mg L−1 in different inflow rivers, and three fluorescence substances (including UVC humic-like, UVA humic-like and tyrosine-like components) were identified by EEM-PARAFAC. The distribution of the DOM components was distinctively different among sampling sites, and UVA humic-like component mainly dominated in Nansi Lake. Meanwhile, DOM components with higher aromaticity and molecular weight were found in the west side of lake. Fluorescence spectral indexes manifested that the source of DOM was mainly from allochthonous or terrestrial input. Moreover, significant correlations between water quality and DOM characteristics were observed in Nansi Lake. These findings would be beneficial to understand the biogeochemical role and impact of DOM in inflowing rivers in the water-quality monitoring and control of storage lakes.

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