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24521. 题目: Competitive adsorption behaviour and mechanisms of cadmium, nickel and ammonium from aqueous solution by fresh and ageing rice straw biochars
文章编号: N20012420
期刊: Bioresource Technology
作者: Yiyi Deng, Shuang Huang, Caiqin Dong, Zhuowen Meng, Xiugui Wang
更新时间: 2020-01-24
摘要: In this study, competitive adsorption behaviour and mechanisms of Cd²⁺, Ni²⁺ and NH₄⁺ by fresh and artificially ageing biochars produced from rice straw at 400 and 700 °C (RB400, RB700, HRB400 and HRB700) were investigated. Cd²⁺ competed with Ni²⁺ and NH₄⁺ for the overlapped adsorption sites on the biochars. For Cd²⁺ and Ni²⁺ adsorption, cation exchange (Q_ci) and mineral co-precipitation (Q_cp) were the primary mechanisms for the low-temperature and high-temperature biochars, respectively. However, the other potential mechanisms (Q_co) made the greatest contributions to NH₄⁺ adsorption (> 60%). Cd²⁺ and Ni²⁺ competition increased the proportions of mineral co-precipitation (Q_cp) and other potential mechanisms (Q_co) but decreased that of cation exchange (Q_ci) mechanism. Biochar ageing increased the contribution of surface complexation (Q_cf) mechanism, especially for the low-temperature biochars. This study indicated that biochar aging and types and states of adsorbates should be considered when biochars were applied to remove contaminants.
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24522. 题目: Spatial distribution of soil organic carbon may be predominantly regulated by topography in a small revegetated watershed
文章编号: N20012419
期刊: CATENA
作者: Haiyan Yu, Tonggang Zha, Xiaoxia Zhang, Lishui Nie, Limin Ma, Yuwei Pan
更新时间: 2020-01-24
摘要: Understanding the spatial distribution and controlling factors of soil organic carbon (SOC) at different scales is essential for an accurate estimation of soil organic carbon stocks. Furthermore, this understanding is vital for evaluating the impact of soil management on both soil quality and climate change. This study was conducted in a Loess revegetated small watershed and the effects of the topography and vegetation factors on the content and distribution of SOC at different soil depths were evaluated. Soil profiles (0–200 cm; n = 122) were sampled that represent six vegetation types (i.e., natural mixed forests, artificial mixed forests, artificial forests with a single tree species, shrubbery, and grassland) and four topographic factors (i.e., elevation, slope gradient, slope position, and slope aspect). The following results were obtained: (1) The mean SOC of the 200 cm soil profile ranged from 2.34 g kg⁻¹ to 5.70 g kg⁻¹, decreasing with increasing soil depth. (2) The interactions between vegetation type and topography and soil depth significantly impacted SOC (P < 0.05). Significant differences in the SOC content (P < 0.05) were also found for slope gradient, slope position, slope aspect, and elevation for 0–200, 0–160, 0–100, and 0–200 cm, respectively. (3) The relative contribution of topographic factors to the SOC content exceeded that of vegetation type in entire soil profile. Topography was the dominant factor controlling the spatial distribution of SOC in the studied small watershed. Therefore, topographic factors should be considered more than vegetation type for an accurate estimation of SOC storage in a revegetated small watershed. This is particularly important for the complicated topography of the loess-gully region.

24523. 题目: MgFe₂O₄-biochar based lanthanum alginate beads for advanced phosphate removal
文章编号: N20012418
期刊: Chemical Engineering Journal
作者: Li Wang, Jingyi Wang, Wei Yan, Chi He, Yijing Shi
更新时间: 2020-01-24
摘要: MgFe₂O₄-biochar based lanthanum alginate beads (MgFe₂O₄-BM-La(b)) were prepared and used for phosphate removal from aqueous solution. MgFe₂O₄-BM-La(b) was synthesized via co-precipitation of Fe and Mg ions onto the reed precursor, followed by gelation-calcination method, in which gelation was achieved by in-situ crosslinking of lanthanum alginate. Based on pre-screen adsorption experiments, MgFe₂O₄-BM-La(b) fabricated under optimal conditions showed the adsorption capacity over 20 times higher than pristine biochar(BC), and about 2.5 times higher than that of beads without the addition of BC or MgFe₂O₄. MgFe₂O₄-BM-La(b) exhibited favorable mass transfer performance through kinetic adsorption comparison between powder and bead type adsorbents. Results from characterization of MgFe₂O₄-BM-La(b) showed the rough morphologies with numerous MgFe₂O₄ nanoparticles adhered on the BC substrate, endowed the bead with excellent magnetic performance for easy separation. In fixed-bed column runs of synthetic secondary treated wastewater (STWW), MgFe₂O₄-BM-La(b) showed the treatment volume of ~1205 BV when effluent phosphate concentration was below 0.5 mg/L, with the capacity loss of about 30% in three continuous adsorption-regeneration cycles. These results illustrated the synergistic effect of MgFe₂O₄, La₂O₃ and BC during phosphate adsorption in practical application. The comparison of FTIR and XPS analyses revealed that through protonation between surface hydroxyl groups and H⁺, the phosphate adsorption of MgFe₂O₄-BM-La(b) was dominated by specific forces ligand exchange and inner-sphere complexation, followed by electrostatic attraction. The superiorities of magnetic bead adsorbent with preferable adsorption capacity and mass transfer performance suggested that MgFe₂O₄-BM-La(b) can serve as a promising filling adsorbent for phosphate removal in industrial application.
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24524. 题目: Synthesis and characterization of magnesium oxide nanoparticle-containing biochar composites for efficient phosphorus removal from aqueous solution
文章编号: N20012417
期刊: Chemosphere
作者: Danchen Zhu, Yingquan Chen, Haiping Yang, Shenghua Wang, Xianhua Wang, Shihong Zhang, Hanping Chen
更新时间: 2020-01-24
摘要: The effective removal and recovery of phosphorus from aquatic environments are highly important for successful eutrophication control and phosphorus recycling. Herein, we prepared biochar containing MgO nanoparticles (MgO-biochar) by fast pyrolysis of MgCl₂-impregnated corn stalks, probed its phosphate adsorption performance. Through the fast pyrolysis, the MgCl₂ promoted the formation of micropores and mesoporous, and decomposed into MgO nanoparticles with the size smaller than 100 nm. The adsorption experiments showed that the adsorption property increased with the increase of Mg content, and had a strong correlation with the external surface area. And the phosphate adsorption was well described by the Langmuir-Freundlich model (maximum adsorption capacity was determined as 60.95 mg P/g). Kinetic analysis and characterization analysis of MgO-biochar for different adsorption time indicated that phosphate adsorption onto MgO-biochar was mainly controlled by rapid binding to the external surface (about 75% of the equilibrium adsorption amount), and the uptake rate was limited by the slow diffusion of phosphate into the biochar interior (about 25% of the equilibrium adsorption amount). The results suggested that the synthesized MgO-biochar with enough MgO active site dispersed on a higher external surface can be used as a potential adsorbent for phosphate removal and recovery from aqueous solution.
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24525. 题目: Iron mineral-humic acid complex enhanced Cr(VI) reduction by Shewanella oneidensis MR-1
文章编号: N20012416
期刊: Chemosphere
作者: Abdelkader Mohamed, Lu Yu, Yu Fang, Noha Ashry, Yassine Riahi, Intisar Uddin, Ke Dai, Qiaoyun Huang
更新时间: 2020-01-24
摘要: Microorganisms, iron minerals, and humic acid are widely common in the soil and water environment and closely interact within environmental processes. In this study, the Cr(VI) removal by Shewanella oneidensis MR-1 (S. oneidensis) was examined in the presence of goethite and humic acid (HA) to mimic the real environment situation. Scanning electron microscopy (SEM) combined with energy disperse spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) technologies were used to probe the Cr(VI) reduction mechanism. Our results showed that S. oneidensis alone could reduce 65% of 1.0 mM Cr(VI) after 8 h of the reduction process. Meanwhile, Cr(VI) reduction rate was declined to 56% in the presence of goethite or humic acid. Contrary, the Cr(VI) reduction rate was mightily increased to 79% by the ternary complex of S. oneidensis-goethite-HA where reduced humic acid (HA_red) acted as electron shuttles and diminished the bacterial adhesion to the goethite surface thereby enhanced electron transfer and increased the extent of Cr(VI) reduction by 1.3 fold. XPS analysis indicated that Cr(VI) was reduced to Cr(III), and the final yields were Cr(OH)₃ and Cr₂O₃ precipitated on the surface of bacterial cells. S. oneidensis could also reduce Fe(III) in goethite to Fe(II), which in turn reduced Cr(VI). These results suggested that iron mineral-humic acid complex could enhance the microbial reduction of Cr(VI) and revealed the promotion role of HA in the Cr(VI) bioreduction process. This study affords inclusive insights on the Cr(VI) reduction kinetics and mechanisms in the most complicated systems.
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24526. 题目: Effect of pyrene on formation of natural silver nanoparticles via reduction of silver ions by humic acid under UV irradiation
文章编号: N20012415
期刊: Chemosphere
作者: Min Liu, Xinyu Gao, Fei Pan, Yuwei Deng, Dongsheng Xia, Zhang Li, Jie Fu
更新时间: 2020-01-24
摘要: This work reported the role of pyrene in formation of naturally occurring silver nanoparticles (AgNPs) via the reduction of silver ions by humic acid under the UV irradiation in the aquatic environment. An increase in temperature (25–90 °C), pH (5–9) or concentration of humic acid (2.5–15 mg/L) led to an enhanced formation of AgNPs. The TEM images indicated the formed AgNPs were spherical with an average particle size of ∼20 nm. Pyrene showed a limited capacity for the photoreduction of silver ions, and when both pyrene and humic acid were present, pyrene would compete with humic acid for the reduction of silver ions. However, the presence of pyrene would enhance the stability and suppress the antibacterial activity of natural AgNPs. The UV–vis spectra of AgNPs suspensions generated with pyrene did not change within 45 days. The inhibition rates against Escherichia coli of AgNPs generated with pyrene were 8–32% lower than those of AgNPs generated without pyrene. This study provides environmental implications on the fate and ecotoxicity of natural AgNPs with interaction of polycyclic aromatic hydrocarbons.
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24527. 题目: Crystalline phase and surface coating of Al₂O₃ nanoparticles and their influence on the integrity and fluidity of model cell membranes
文章编号: N20012414
期刊: Chemosphere
作者: Bao Zhu, Xiaoran Wei, Jian Song, Qiu Zhang, Wei Jiang
更新时间: 2020-01-24
摘要: Aluminium oxide nanoparticles (Al₂O₃ NPs) potentially cause health hazards after their release into the environment. The crystalline phase of Al₂O₃ NPs determines their surface structure and the number of functional groups. The adsorption of natural organic matter (NOM) or biomolecules on the surface Al₂O₃ NPs also alters their surface properties and subsequent interactions with organisms. In this study, the roles of the Al₂O₃ crystalline phase and the surface coating of the nanoparticles on the membrane integrity and fluidity were investigated. Giant and small unilamellar vesicles (GUVs and SUVs) were prepared as model cell membranes to detect membrane disruption after exposure to Al₂O₃ NPs. Due to amorphous structure and high surface activity of γ-Al₂O₃ NPs, they had a stronger affinity with the membrane and caused more serious membrane rupture than that of α-Al₂O₃ NPs. The deposition of Al₂O₃ NPs on the membrane and the induced membrane disruption were monitored by a quartz crystal microbalance with dissipation (QCM-D) method. HA-coated Al₂O₃ NPs disrupted the SUV layer on the QCM-D sensor, while BSA-coated Al₂O₃ NPs only adhered to the membrane and induced unremarkable vesicle disruption. In addition, untreated γ-Al₂O₃ NPs induced remarkable gelation of a negatively charged membrane, but other types of Al₂O₃ NPs caused negligible membrane phase changes. The outcomes of this study demonstrate that the crystalline phase of the Al₂O₃ NPs affects the integrity and fluidity of cell membranes. The protein coatings on the NPs weaken the NP-membrane interaction, while HA coatings increase the damage of the NP-induced interaction.
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24528. 题目: The role of magnetic MOFs nanoparticles in enhanced iron coagulation of aquatic dissolved organic matter
文章编号: N20012413
期刊: Chemosphere
作者: Guocheng Zhu, Yongning Bian, Andrew S. Hursthouse, Shengnan Xu, Nana Xiong, Peng Wan
更新时间: 2020-01-24
摘要: Dissolved organic matter (DOM) is not only a vector for the migration of aquatic environmental pollutants, but is also key to the control of water pollution. Economic and effective DOM removal through coagulation is essential in water treatment processes. This work investigated the role of carboxylated magnetic metal organic frameworks (MMOFs) nanoparticles in polymeric iron-based coagulation for the removal of aquatic DOM using a MMOFs-doped polyferric iron-based coagulant (MMOF-PIC). Analytical methodologies and tools used in this research included scanning electron microscopy (SEM), zeta potential, molecular weight cut off (MWCO), vibrating sample magnetometer (VSM) measurement, excitation emission matrix spectroscopy (EEMs), and X-ray photoelectron spectroscopy (XPS). The results showed that MMOF-PIC had the potential to change the structure of the polyferric iron-based coagulant (PIC) and charge, as determined by a porous surface morphology, a higher medium polymeric species distribution, and a more positive zeta potential. The MMOFs consequently enhanced PIC action on the removal of UV254 exposed DOM species with molecular weight <30 kDa, including aromatic CC based compounds, org-N as primary amines and amide/peptide bound species, water containing microbial metabolites and protein-like materials. The coagulation of DOM was enhanced by improving charge neutralization, adsorption-bridging and sweep-flocculation in the presence of MMOFs nanoparticles. This was due to hydrogen bonds, π-π bonds and covalent bonds resulting from actions of nanoparticles and pollutants. These results indicate that magnetic MOF nanoparticles can improve PIC coagulation for DOM, enhancing future removal of target pollutants.
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24529. 题目: Effect of biochars on bioaccumulation and human health risks of potentially toxic elements in wheat (Triticum aestivum L.) cultivated on industrially contaminated soil
文章编号: N20012412
期刊: Environmental Pollution
作者: Nisar Muhammad, Mohammad Nafees, Muhammad Haya Khan, Liya Ge, Grzegorz Lisak
更新时间: 2020-01-24
摘要: In the present study, biochars (BCs) derived from naturally grown green waste (Cynodon dactylon L.) were investigated regarding their impacts on bioaccumulation of potentially toxic elements (PTEs), agronomic properties and human health risks of wheat crop cultivated on long-term industrially contaminated soil. Typically, three types of BCs were pyrolyzed at different highest temperature of treatment (HTT), i.e. 400 °C, 600 °C and 800 °C, in a horizontal reactor and applied to the contaminated soil with 2% and 5% (w/w) ratio. The characterization results of the BCs showed that significant positive changes in fundamental characteristics such as porosity, surface area, cation exchange capacity, dissolved organic carbon, phosphorus and potassium have occurred with increased HTT. The analytical results of wheat crop indicated that the BCs applications significantly (p ≤ 0.05) reduced concentration of PTEs in roots (48–95%), shoots (38–91%), leaves (30–91%) and grains (38–93%) of wheat plants. After the BCs application, the agronomic properties were enhanced up to 6–18%, 18–38%, 17–46%, 13–45%, 15–42%, 22–55% and 34–57% for germination rate, shoot length, shoot biomass, spike length, spike biomass, grain biomass and root biomass respectively. The human health risks of PTEs were significantly (p ≤ 0.05) decreased (31–93%) from toxicity level to safe level (except for Mn and Cu), after the BCs application. Based on the current study, the BCs (especially 800BC5) were recommended for reducing bioaccumulation of PTEs in different parts of the wheat plant, increasing growth and yield of wheat crop and decreasing human health risks via consumption of wheat grains.
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24530. 题目: Sulfur isotope composition of individual compounds in immature organic-rich rocks and possible geochemical implications
文章编号: N20012411
期刊: Geochimica et Cosmochimica Acta
作者: Lubna Shawar, Ward Said-Ahmad, Geoffrey S. Ellis, Alon Amrani
更新时间: 2020-01-24
摘要: We applied compound-specific sulfur isotope analysis (CSSIA) to organic matter (OM) extracted from ancient and immature organic-rich rocks from the Cretaceous Ghareb (Shefela Basin locality, Israel) and Miocene Monterey (Naples Beach locality, California, USA) Formations. Large variations in the δ³⁴S values of different organosulfur compounds (OSCs), that reach up to 28‰ and 36‰, were observed in the Ghareb and Monterey samples, respectively. Additionally, some common OSCs in both locations showed consistent ³⁴S trends relative to each other. The consistent enrichment in ³⁴S of C₃₅ hopane thiophene relative to iC₂₀ thiophene in the studied sections probably resulted from differences in the timing of OM sulfurization. Reactive organic precursors quickly consume the most ³⁴S-depleted reduced S, while less reactive species incorporate the heavier residual S at a later time. Despite the differences in the depositional environments, ages, and the initial δ³⁴S values of the reduced S (represented by the δ³⁴S of pyrite) between the Ghareb and the Monterey Formations, the sulfurization order of common organic compounds seems to be similar. All of the δ³⁴S values of OSCs are ³⁴S enriched relative to that of the coexisting pyrite with the exception of the C₂₅ highly branched isoprenoid (HBI) thiophene in several samples from the Monterey Formation. The existence of ³⁴S-depleted sulfurized HBI may point to OM sulfurization that occurred at or near the sediment-water interface during the deposition of the Monterey. Moreover, the δ³⁴S of steroid sulfides shows an inverse trend with the pristane/phytane ratio, which may indicate that the sulfurization mechanism of these OSCs are affected by redox conditions. Further investigation of CSSI values in immature rocks from other basins may help constrain the OM sulfurization process, timescale, and depositional conditions and their possible use as paleoenvironmental proxies.

24531. 题目: Dissolution susceptibility of glass-like carbon versus crystalline graphite in high-pressure aqueous fluids and implications for the behavior of organic matter in subduction zones
文章编号: N20012410
期刊: Geochimica et Cosmochimica Acta
作者: Simone Tumiati, Carla Tiraboschi, Francesca Miozzi, Alberto Vitale-Brovarone, Craig E. Manning, Dimitri Sverjensky, Sula Milani, Stefano Poli
更新时间: 2020-01-24
摘要: Organic matter, showing variable degrees of crystallinity and thus of graphitization, is an important source of carbon in subducted sediments, as demonstrated by the isotopic signatures of deep and ultra-deep diamonds and volcanic emissions in arc settings. In this experimental study, we investigated the dissolution of sp² hybridized carbon in aqueous fluids at 1 and 3 GPa, and 800°C, taking as end-members i) crystalline synthetic graphite and ii) X-ray amorphous glass-like carbon. We chose glass-like carbon as an analogue of natural “disordered” graphitic carbon derived from organic matter, because unlike other forms of poorly ordered carbon it does not undergo any structural modification at the investigated experimental conditions, allowing approach to thermodynamic equilibrium. Textural observations, Raman spectroscopy, synchrotron X-ray diffraction and dissolution susceptibility of char produced by thermal decomposition of glucose (representative of non-transformed organic matter) at the same experimental conditions support this assumption. The redox state of the experiments was buffered at ΔFMQ ≈ –0.5 using double capsules and either fayalite-magnetite-quartz (FMQ) or nickel-nickel oxide (NNO) buffers. At the investigated P–T–fO₂ conditions, the dominant aqueous dissolution product is carbon dioxide, formed by oxidation of solid carbon. At 1 GPa and 800°C, oxidative dissolution of glass-like carbon produces 16–19 mol% more carbon dioxide than crystalline graphite. In contrast, fluids interacting with glass-like carbon at the higher pressure of 3 GPa show only a limited increase in CO₂ (fH₂^NNO) or even a lower CO₂ content (fH₂^FMQ) with respect to fluids interacting with crystalline graphite. The measured fluid compositions allowed retrieving the difference in Gibbs free energy (ΔG) between glass-like carbon and graphite, which is +1.7(1) kJ/mol at 1 GPa–800°C and +0.51(1) kJ/mol (fH₂^NNO) at 3 GPa–800°C. Thermodynamic modeling suggests that the decline in dissolution susceptibility at high pressure is related to the higher compressibility of glass-like carbon with respect to crystalline graphite, resulting in G–P curves crossing at about 3.4 GPa at 800°C, close to the graphite–diamond transition. The new experimental data suggest that, in the presence of aqueous fluids that flush subducted sediments, the removal of poorly crystalline “disordered” graphitic carbon is more efficient than that of crystalline graphite especially at shallow levels of subduction zones, where the difference in free energy is higher and the availability of poorly organized metastable carbonaceous matter and of aqueous fluids produced by devolatilization of the downgoing slab is maximized. At depths greater than 110 km, the small differences in ΔG imply that there is minimal energetic drive for transforming “disordered” graphitic carbon to ordered graphite; “disordered” graphitic carbon could even be energetically slightly favored in a narrow P interval.

24532. 题目: Controls on the shuttling of manganese over the northwestern Black Sea shelf and its fate in the euxinic deep basin
文章编号: N20012409
期刊: Geochimica et Cosmochimica Acta
作者: W.K. Lenstra, M.J.M. Séguret, T. Behrends, R.K. Groeneveld, M. Hermans, R. Witbaard, C.P. Slomp
更新时间: 2020-01-24
摘要: Manganese (Mn) is an essential micronutrient for phytoplankton and its cycling interacts with that of iron (Fe). Continental shelf sediments are a key but poorly quantified source of Mn to marine waters. In this study, we investigate Mn release from shelf sediments, its lateral transport (”shuttling”) in the oxic water column over the northwestern Black Sea shelf and its fate in the adjacent euxinic deep basin. We find a high release of Mn from organic-rich, bioirrigated coastal sediments, but negligible mobilization and release of Mn from sediments in offshore shelf regions, because of a low input of organic matter. Most Mn in the water column is present in dissolved form. We suggest that this dissolved Mn is released from coastal sediments and subsequently transported offshore through physical processes. Surface sediments at open shelf and shelf edge stations are highly enriched in Mn when compared to coastal and deep basin stations. Only part of the surface enrichment can be explained by oxidation of porewater Mn. The remainder of this enrichment is likely the result of oxidative removal of dissolved Mn from the water column and deposition as Mn oxides. Using X-ray spectroscopy we show that Mn in surface sediments in this area predominately consists of Mn(IV) oxides (phyllo- and/or tectomanganates). A key difference between Mn versus Fe shuttling is the form in which the metal is transported: while dissolved Mn dominates in the water column over the shelf, most Fe is present in particulate form. Sediment trap data indicate that the vertical transport of both Mn and Fe through the euxinic water column is correlated and is associated with the sinking flux of biogenic particulate matter following the spring and fall phytoplankton blooms. In the sediments of the euxinic basin, Mn is enriched when compared to a detrital Mn background and its burial correlates with that of Fe. This suggests that Mn could be incorporated in pyrite in the euxinic water column. Our results highlight the critical role of organic matter input as a driver of Mn and Fe shuttling over the Black Sea continental shelf and particulate matter as the carrier of Mn and Fe into the euxinic basin.

24533. 题目: Effect of biochar on desiccation cracking characteristics of clayey soils
文章编号: N20012408
期刊: Geoderma
作者: Yuping Zhang, Kai Gu, Jinwen Li, Chaosheng Tang, Zhengtao Shen, Bin Shi
更新时间: 2020-01-24
摘要: Biochar is a promising material for soil remediation. However, the influence of biochar on soil cracking has not been clearly understood to date. Soil cracking can significantly change the mobility of contaminants in soil and consequently the remediation performance of biochar. This study investigates the effect of a wood biochar on the desiccation shrinkage characteristics of two clayey soils (PKE and XS). The biochar dosages selected are 0%, 0.5%, 2%, 4%, 6%, and 10% (w/w). The results indicate that biochar affects the desiccation cracking characteristics of clayey soils by changing the evaporation process. For PKE, the evaporation rate decreased by 6.56% and 5.59% with 0.5% and 2% biochar addition, respectively, and increased by 2.11% and 17.20% with 4% and 6% biochar addition. Similarly, with the biochar dosage ranges from 0.5% to 10% for XS soil, the evaporation rate decreased by 8.57%, 8.73%, 4.56%, and increased by 0.96% and 41.06%, respectively. Image processing analysis on the cracks indicates that the addition of biochar decreases the quantitative parameters such as the crack ratio, the number of soil mass and the fractal dimension for both treated soils. The crack ratio, the number of cracks and the number of soil mass were reduced by 16.85%, 32.26% and 39.22% for 4% biochar addition in PKE. The value of XS soil with 6% biochar addition decreased by 30.80%, 8.28%, and 11.61%, respectively. Furthermore, biochar can effectively reduce the width of cracks. The role of biochar in the development of desiccation cracking may include (1) occupying the shrinkage space of soil particles; (2) weakening the bonding between soil particles and (3) providing hydrophobic channels. In general, the application of 4% and 6% biochar in PKE and XS respectively has the best performance in inhibiting soil cracking.

24534. 题目: Biochar’s stability and effect on the content, composition and turnover of soil organic carbon
文章编号: N20012407
期刊: Geoderma
作者: Lanfang Han, Ke Sun, Yan Yang, Xinghui Xia, Fangbai Li, Zhifeng Yang, Baoshan Xing
更新时间: 2020-01-24
摘要: Extensive application of biochar to soil exerts a profound effect on organic carbon (OC) in soils. However, the impact of biochar on the content and composition of OC has not been comprehensively summarized. This review provided a detailed examination on the stability of biochar and its effect on the amount, composition and turnover of soil OC, with key limitations and issues recognized. The direct input of labile and stable OC of biochar to soil OC pool, and indirect effects of biochar on soil OC by affecting soil physicochemical and biological properties were discussed. Both low stability of biochar and biochar-induced strong positive priming effect on OC mineralization were commonly observed in sandy soil added with biochar produced from manure at low temperature. The stable OC of biochar was composed of both aromatic OC and the OC fractions stabilized by soil minerals. Biochar mainly increased the formation of macro-aggregates, and this promotion was more intense for clayey soil added with manure-based low temperature-biochar. Additionally, potential influential mechanisms were proposed to explain the effect of biochar addition on amount and composition of humic substances in soils. This review will shed lights on the effect of biochar application on the amount, composition and turnover of native soil OC, and improve the understanding of the ecological effect of biochar on the soil functions.
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24535. 题目: Deciphering of organic matter and nutrient removal and bacterial community in three sludge treatment wetlands under different operating conditions
文章编号: N20012406
期刊: Journal of Environmental Management
作者: Shiquan Wang, Yubo Cui, Aimin Li, Wanjun Zhang, Dong Wang, Zhaobo Chen, Junyu Liang
更新时间: 2020-01-24
摘要: Sludge treatment wetlands (STWs) can effectively stabilize sludge, but the microbial community structure in this process is not well characterized. The purpose of this study was to investigate the characteristics of organic matter and nutrient removal and bacterial community in sludge treatment wetlands for treating sewage sludge. Three STWs units included unit STW1 with aeration tubes, unit STW2 with aeration tubes and reed planting and unit STW3 with reed planting. The degradation of organic matter and nutrient, sludge dewatering performance and microbial community dynamics in STWs were examined in feeding and resting periods. Our results showed that during the entire process of the experiment, total solids (TS) in STWs increased to 24–31%, volatile solids (VS) in STWs reduced to 43–47%, while the total kjeldahl nitrogen (TKN) and total phosphorous (TP) concentrations in STWs decreased to 25.1–35.5 mg/g d. w and 5.4–6.2 mg/g d. w. However, the removal efficiencies of organic matter and nutrient in STWs in the feeding period were higher than those in the resting period. Meanwhile, unit STW2 has the best removal performance in organic matter and nutrients during the whole experiment. Microbial community analysis using Illumina MiSeq sequencing technology showed that growth of plants in STWs improved bacterial diversity and richness which corresponded to high removal rates of organic matter and nutrient. Besides, principal coordinate analysis (PCoA) showed that the bacterial community composition in STWs obviously altered between the feeding and the resting periods.
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24536. 题目: The mechanism of cadmium sorption by sulphur-modified wheat straw biochar and its application cadmium-contaminated soil
文章编号: N20012405
期刊: Science of The Total Environment
作者: Dun Chen, Xiaobing Wang, Xiaoli Wang, Ke Feng, Jincheng Su, Junneng Dong
更新时间: 2020-01-24
摘要: Cadmium (Cd) pollution in soils has received considerable research attention globally, and sulphur-modified biochar (SBC) could combine the advantages of biochar and the sulphur element for Cd remediation. Biochar from agricultural waste is feasible, which has a low preparation cost. However, there are few studies regarding the effects of the sulphur modification of biochar on the Cd immobilization mechanism. This study aimed to research the Cd immobilization mechanism of pristine wheat straw biochar (BC) and sulphur-modified biochar (SBC), and the Cd immobilization effects of BC and SBC in Cd-contaminated soils. Elemental and SEM analysis confirmed that sulphur was successfully loaded on the pristine biochar. XPS analysis confirmed that there was a considerable discrepancy between adsorption mechanisms of Cd on BC and SBC. In particular, cadmium sorption on BC was due to Cd(OH)₂ and CdCO₃ precipitation formation and interaction with carbonyl and carboxyl groups, whereas on SBC, sorption was mainly due to CdS and CdHS⁺ formation and interaction with organic sulphide. In the incubation experiment, SBC and BC additions increased pH value and also reduced the available Cd concentrations in the soil. Compared with the control, the contents of available Cd in soil were significantly decreased by 15.86% ~ 22.10% and 22.72% ~ 27.90%, following treatments with BC and SBC, respectively.
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24537. 题目: Synthesis, characterization and application of magnetic and acid modified biochars following alkaline pretreatment of rice and cotton straws
文章编号: N20012404
期刊: Science of The Total Environment
作者: Muhammad Rizwan, Qimei Lin, Xuejiao Chen, Yangyang Li, Guitong Li, Xiaorong Zhao, Yanfang Tian
更新时间: 2020-01-24
摘要: The development of distinct biochar from agricultural waste for soil and environment remediation is valuable. Moderate pretreatment with sodium hydroxide may open the lignocellulosic structure of crop straw and then enhance the impregnation of iron oxides and phosphates, finally leading to the production of distinct biochars. In this study, two common agricultural wastes of rice and cotton straw were first treated with a dilute NaOH solution and then soaked in either Fe-Co nitrate or H₃PO₄ solution. The biochars produced through a slow pyrolysis process were then analyzed with respect to their physico-chemical and adsorptive properties. The results showed that all pretreatments remarkably changed the physico-chemical properties of the feedstocks and subsequently endowed the biochars with distinct characteristics. The biochars had specific surface areas (SSAs) ranging from 12.26 to 581.13 m²/g, total pore volumes (TPVs) ranging from 0.033 to 0.3736 cm³/g and average pore volumes (APSs) ranging from 2.57 to 10.76 nm. They also contained a large amount of positive charge, an anion exchange capacity (pH 3.5) ranging from 251.78 to 810.13 mmol/kg, and a certain amount of negative charge as well, cation exchange capacity (pH 7.0) ranging from 108.22 to 464.67 mmol/kg. The adsorption capacities of the modified biochars toward both Pb²⁺ and Cd²⁺ were 23.07–82.74% and 16.90–556.33% higher than those of pristine biochars, respectively. Of the modified biochars, the Fe-Co-composite biochar showed many promising physico-chemical and adsorptive properties for adsorbing divalent metals of both Pb²⁺ and Cd²⁺ and might thus have high potential as a soil amendment and an alternative adsorbent for environmental remediation.
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24538. 题目: Influence of polystyrene microplastics on the growth, photosynthetic efficiency and aggregation of freshwater microalgae Chlamydomonas reinhardtii
文章编号: N20012403
期刊: Science of The Total Environment
作者: Shuangxi Li, Panpan Wang, Chao Zhang, Xiangjun Zhou, Zhihong Yin, Tianyi Hu, Dan Hu, Chenchen Liu, Liandong Zhu
更新时间: 2020-01-24
摘要: Microplastics are ubiquitous in aquatic ecosystems worldwide, but knowledge on their impacts on phytoplankton, especially freshwater microalgae, is still limited. To investigate this issue, microalgae Chlamydomonas reinhardtii was exposed to polystyrene (PS) microplastics with 4 concentration gradients (5, 25, 50 and 100 mg/L), and the growth, chlorophyll a fluorescence, photosynthetic activities (Fv/Fm), the contents of malondialdehydes (MDA), soluble proteins, extracellular polymeric substances (EPS) and settlement rate were accordingly measured. Results showed that the density of microalgae decreased as the increase of PS microplastics concentrations, and the highest inhibitory rate (IR) was 45.8% on the 7th day under the concentration of 100 mg/L. The high concentration (100 mg/L) of microplastics evidently inhibited the content of EPS released by microalgae into the solution. PS under all dosages tested could reduce both the chlorophyll a fluorescence yields and photosynthetic activities. The scanning electron microscope (SEM) images demonstrated that microplastic beads were wrapped on the surface of microalgae and damaged their membranes, which could suggest the reduction of photosynthetic activities and the increase of soluble proteins and MDA content. The results also showed that PS microplastics could inhibit the settlement of microalgae at the later stage, which also indicated the recovery of microalgae from the toxic environment. Our findings will contribute to understanding the effects of microplastics on freshwater microalgae, as well as evaluating the possible influences of microplastics on aquatic ecosystems.
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24539. 题目: Levels and variations of soil organic carbon and total nitrogen among forests in a hotspot region of high nitrogen deposition
文章编号: N20012402
期刊: Science of The Total Environment
作者: Tian-Yi Ma, Xue-Yan Liu, Shi-Qi Xu, Hao-Ran Guo, Hao Huang, Chao-Chen Hu, Di Wu, Zhong-Cong Sun, Chong-Juan Chen, Wei Song
更新时间: 2020-01-24
摘要: Human activities have distinctly enhanced the deposition levels of atmospheric nitrogen (N) pollutants into terrestrial ecosystems, but whether and to what extents soil carbon (C) and N status have been influenced by elevated N inputs remain poorly understood in the ‘real’ world given related knowledge has largely based on N-addition experiments. Here we reported soil organic C (OC) and total N (TN) for twenty-seven forests along a gradient of N deposition (22.4–112.9 kg N/ha/yr) in the Beijing-Tianjin-Hebei (BTH) region of northern China, a global hotspot of high N pollution. Levels of soil TN in forests of the BTH region have been elevated compared with investigations in past decades, suggesting that long-term N deposition might cause soil TN increases. Combining with major geographical and environmental factors among the study forests, we found unexpectedly that soil moisture and pH values rather than N deposition levels were major regulators of the observed spatial variations of soil OC and TN contents. As soil moisture and pH values increased with mean annual precipitation and temperature, respectively, soil C and N status in forests of the BTH region might be more responsive to climate change than to N pollution. These evidence suggests that both N deposition and climate differences should be considered into managing ecosystem functions of forest resources in regions with high N pollution.
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24540. 题目: Sorption of oxytetracycline in particulate organic matter in soils and sediments: Roles of pH, ionic strength and temperature
文章编号: N20012401
期刊: Science of The Total Environment
作者: Xinghua Liu, Haibo Zhang, Yongming Luo, Rongsheng Zhu, Huaizhong Wang, Baohua Huang
更新时间: 2020-01-24
摘要: Particulate organic matter (POM) is a fraction of organic matter with dissimilar properties in different soils. POM isolated from soils and sediments (wetland, oil waste field, farmlands and aquaculture pond sediment) was used to study its sorption behavior on the antibiotic oxytetracycline (OTC). Impacts of solution pH, ionic strength and temperature on the OTC sorption were studied. The sorption rates of OTC in POM from wetland (POM-w) and farmland (POM-f1, POM-f2) were rapid during the first 3 h and gradually decreased with reaction time until reaching the equilibrium. Linear sorption occurred from 3 to 12 h in POM from oil waste field land (POM-o) and aquaculture pond sediment (POM-a). The organic carbon normalized partition coefficient (k_oc) varied from 215.0 to 4493.6 L kg⁻¹, and it was nearly 10× higher for the POM-w, POM-f1 and POM-f2 than in the POM-o and POM-a. Sorption of OTC by POM exhibited strong pH dependence. Ionic factors affected OTC sorption in POM-f1, POM-f2 and POM-a. The sorption capacity declined >50% in a solution with Ca²⁺ compared to other ions with similar ionic strength. Sorption thermodynamics showed an entropy increasing and endothermic progress during the OTC sorption in POM, implying a spontaneous sorption process. Several mechanisms were involved in OTC sorption in POM, including hydrogen bonding, cation exchange, hydrophobic partitioning and surface complexation.
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