61. 题目: Organic amendments improved soil quality and reduced ecological risks of heavy metals in a long-term tea plantation field trial on an Alfisol.
期刊: Science of The Total Environment
作者: Xiaoyun Yi, Linfei Ji, Zhenmin Hu, Xiangde Yang, Haitao Li, Yanyan Jiang, Tiehu He, Yangyi Yang, Kang Ni, Jianyun Ruan
摘要: Tea plantation can cause strong soil degradation, e.g. acidification, basic nutrient decrease and microbial diversity loss, naturally by its root activity and secondary by practically tremendous synthetic N input. Organic amendments application is considered a practical way to mitigate the above adverse consequence. However, the trade-off between agronomic and environmental effects on the application of the organic amendments is still under debate. Herein, we conducted a long-term field experiment with four treatments, including control (without and fertiliser) (CK), chemical fertiliser treatment (CF), chicken manure treatment (CM) and chicken manure combined with biochar treatment (CMB) to investigate the effects of organic amendments application on soil quality, heavy metal contamination and tea production in a tea plantation. Totally 16 plots were arranged randomly with a completely randomised design. The results showed that CM and CMB treatments improved soil nutrient, mitigated soil acidification and ameliorated soil porosity compared to CF treatment. CMB treatment displayed a relatively high tea yield and quality in three consecutive years of monitoring. However, CM and CMB treatments elevated the heavy metal (HM) potential ecological risk (RI) and Nemerow's composite index (Ps). CM treatment significantly increased available As, Pb, Cu and Zn concentrations compared to CF treatment, while CMB treatment significantly decreased available Cr and Cu concentrations and slightly decreased available Cd, Pb and Ni concentrations compared to CM treatment. But the increase of available As and Zn in CMB treatment compared to CM treatment also indicated adverse effects of biochar addition. The PLS-PM model showed HM risk had direct negative effects on tea quality. Moreover, soil fungal community revealed positive effects on tea yield and negative effects on tea quality. Overall, our study proved that CMB treatment could improve soil quality, reduce available Cr and Ni concentrations, maintain tea yield and increase tea quality.
62. 题目: Insights on free radical oxidation and in-situ coagulation in PMS/Fe(II) process for the removal of algogenic organic matter precursors
期刊: Chemical Engineering Journal
作者: Lap-Cuong Hua, Ching Huang, Chihpin Huang
摘要: Algogenic organic matter (AOM) is unwelcome in raw water as it is a major precursor of carcinogenic disinfection byproducts (DBPs). Unfortunately, conventional coagulation is ineffective against AOM, raising the need for a better alternative for AOM and AOM-derived-DBP removal. This study examined the effectiveness and underlying mechanisms of a novel hybrid oxidation-coagulation PMS/Fe(II) process for effective removal of AOM-DBP precursors. Under optimal conditions, only PMS/Fe(II) or combined PMS/Fe(II) with Al/Fe coagulation removed significant amounts of dissolved organic carbon (DOC) (45-52%) and 50-65% AOM-fluorescent components. These values were much better than conventional Al/Fe coagulations (e.g. 15-19% DOC and <40% fluorescent components at [Fe3+]=[Al3+]=100 μM, pH 5.5-6). AOM-derived DBPs were thus significantly eliminated (>80% of total DBP levels) after PMS/Fe(II) related processes, which markedly outperformed Al/Fe coagulations (of only 20–30%). PMS/Fe(II) presented its strongest oxidative ability at pH 4 (with [SO4•−]=2.16×10-12 and [•OH]=1.26×10-12 M), rather than at pH 7 or 9. Acidic conditions rapidly increased oxidized-carbon contents (e.g. %ketone + %carbonyl increased from 10% to 25%) in AOM structure after PMS/Fe(II) treatment. By contrast, pH 7 and 9 were the favorable conditions for in-situ coagulation with faster floc aggregation and growth rates than pH 4. Regardless, PMS/Fe(II) process performed best in effectively removing AOM-DBP precursor only under neutral pH of 6-7 by gaining the synergistic benefits of free radical oxidation and in-situ coagulation. Our findings are a significant contribution to filling the knowledge gap in the study of PMS/Fe(II) and highlight the possibilities of this novel hybrid process as an alternative to conventional coagulation for sustainable water treatment.
63. 题目: UV/O3 assisted ceramic membrane reactor for efficient fouling control and DOM transformations in real textile wastewater
期刊: Separation and Purification Technology
作者: Ch. Tahir Mehmood, Weiyu Tan, Yuzhen Chen, Hira Waheed, Yiwei Li, Yeyuan Xiao, Ziyi Zhong
摘要: A ceramic membrane reactor (CMR) coupled with an up-flow anaerobic sludge blanket (UASB) reactor has been investigated to treat real textile wastewater, focusing on the synergetic effects of UV and O3 on fouling control and dissolved organic matter (DOM) transformation. The ozone treatment showed high potential in color removal but resulted in a linear (R2=0.996) increase in the membrane fouling rate with the increasing ozone dose; the continuous UV (254 nm) exposure significantly retarded membrane fouling by 16 folds but increased soluble chemical oxygen demand. In contrast, when intermittent (15 min ON: 15 min OFF) UV exposure and ozonation (UV/O3) were applied simultaneously, 94% color removal was reached and a synergistic effect on membrane fouling control was prominent, which increased the fouling time by 2.92 and 10.1 folds as compared to the standalone application of UV or ozone, respectively. Confocal laser scanning microscopy observation revealed proteins and polysaccharides as prominent foulants during O3 and UV treatment, respectively. UV-Vis spectroscopy and 3-D excitation-emission matrix fluorescence spectra confirmed the synergistic effects of UV/O3 in the degradation of UV280 and UV254 absorbance and fluorescent DOM. The HO• radicals played a primary role in degrading organic pollutants during UV/O3 treatment. These results provide new insights into the fouling mechanism and DOM transformation in ceramic membrane-based wastewater treatment systems, and recommend simultaneously intermittent application of UV/O3 in an external CMR coupled to UASB as a promising technology for the treatment of textile or other industrial wastewater.
64. 题目: Effect of amino acids on the stability of anionic pollutants in fly ash blended cement
期刊: Journal of Environmental Chemical Engineering
作者: Mengmeng Wang, Keiko Sasaki
摘要: Fly ash has been used as cementitious materials for solid waste immobilization. However, fly ash typically contains the hazardous elements Se, Cr, As, and B, and the leachability of these anions is a concern for its reuse. In this study, five amino acids were selected as models of simplified natural organic matter (NOM) in the pedosphere to modify the dissolution tests of Se, Cr, As, and B in ground fly ash blended cement. At the initial pH of 4.7, hydrocalumite and ettringite were easily dissolved, so Ca salt precipitates played an important role in immobilizing oxyanions. However, the stability of Ca salts was weakened by the ligand-promoted dissolution mechanism. In particular, the formation of complexes of H2Asp and HGly with Ca2+ promoted the release of Se, Cr, and As. H2Cys, on the other hand, acted as a reducing reagent to suppress Se and Cr mobility. At the initial pH of 12.0, the stable formation of hydrocalumite and ettringite effectively immobilized the anionic species. Under this condition, aside from the complexation of amino acids with Ca2+, the ion exchange between deprotonated amino acids and oxyanions in hydrocalumite interlayer may also threaten the stability of undesirable anionic species. However, the adsorption of amino acids on the surface of ettringite and hydrocalumite may inhibit their dissolution, resulting in a decrease in Se, Cr, As, and B release. This work provides a reference for understanding the stability of undesirable anionic pollutants in fly ash blended cement when they are exposed to geochemical environments.
65. 题目: Nickel and Its Oxide-Modified Biochar for Enhanced Removal of Ammonia: Theoretical Study and Practical Application
期刊: Water, Air, & Soil Pollution
作者: Chao Gao, Zhonglong Yin, Zifan Liu, Zepeng Zhang, Zhen Yang, Weiben Yang
摘要: A series of metal- and metal oxide-modified biochars were prepared to remove ammonia (NH3). Maize straw was used as the precursor to fabricate biochar, four kinds of biochar with different metal modification were prepared by impregnation method, and the part of metal on the surface of biochar was converted to metal oxide after secondary pyrolysis. It was found that adsorption capacity of BC-Ni–O on NH3 was the highest (118.6 mg/g), which was due to the strong coordination and complexation between metal nickel and ammonia molecules. BC-Ni–O also shows good cycling performance. The mechanism analysis shows that the formation of metal oxides can increase the specific surface area of the adsorbent which plays an important role in the adsorption. The formation of NiO and Ni2+ in secondary pyrolysis plays a major role in the adsorption process, and their contribution is about 86%. To assess the reliability of adsorbent in practical application, the air purification experiment was conducted in a 30-m3 air chamber. High removal rate of ammonia is recorded 85.9% in single-component gas, and it still maintained at 72.6% in a mixed-component gas (the concentration of toluene, formaldehyde, and ammonia is 1 mg/m3, 1 mg/m3, and 1.5 mg/m3, respectively).
66. 题目: One-pot synthesis of a magnetic Zn/iron-based sludge/biochar composite for aqueous Cr(VI) adsorption
期刊: Environmental Technology & Innovation
作者: Zhihong Zheng, Xiaohan Duan, Jingxi Tie
摘要: Using the traditional Chinese medicine residual (TCMR) as biomass, and the iron-based waterworks sludge (IBWS) and Zinc chloride (ZnCl 2) as modified materials, this study synthesized IBWS/ZnCl 2/TCMR-derived biochar composite (Fe-Zn@BC) in one-pot technique for aqueous Cr(VI) adsorption. Batch experiments of Cr(VI) adsorption were carried out with the Fe-Zn@BC as an adsorbent. The pH research revealed that acidic conditions (pH < pHzpc) were in favor of Cr(VI) adsorption, with the highest removal observed at pH 2. The maximum adsorption capacity of Fe-Zn@BC was about 27.04 mg/g at 35 °C. Based on the examination of kinetics, isotherm, the adsorption process by Fe-Zn@BC was consistent with the equation of pseudo-second-order and the Langmuir model, which had a monolayer adsorption nature. Anions have negative effects on Cr(VI) reduction by Fe-Zn@BC, the negative effects order followed Cl−< SO42−< PO43−, which were positive correlated with the concentration and the charge of anions. Potential removal mechanism was investigated with various characterization techniques, indicating that the major mechanisms of Cr(VI) adsorption by Fe-Zn@BC were physical and chemical adsorption, including the reaction of Cr(VI) to Cr(III). IBWS was calcined to impart magnetism of composite, and ZnCl 2 generated magnetic zinc ferrite (ZnFe 2O4) while activating the composite, endowing the composite with enhanced Cr(VI) adsorption capability and stronger magnetism. Therefore, Fe-Zn@BC appears to be a viable material for removing Cr(VI) in wastewater.
67. 题目: Size-dependent transport and fouling formation of organic matters in a pilot-scale PFFO–RO hybrid system for real wastewater treatment
期刊: Journal of Cleaner Production
作者: Ganghyeon Jeong, Hyeonho Lee, Chang-Min Kim, Am Jang
摘要: The forward osmosis (FO)-reverse osmosis (RO) hybrid system has been gaining considerable interest because of its wide applicability and feasibility in both wastewater treatment and seawater desalination. However, as the FO process treats wastewater in the hybrid system, fouling of the FO membrane is a crucial factor in the FO-RO hybrid system, which determines the performance of the entire hybrid system. A few studies have reported that the configuration of the PFFO module has potential advantages, such as a higher cross flow velocity, higher fouling resistance, and lower pressure drop compared to conventional spiral wound-type modules. In this study, the first to investigate the performance of the PFFO-RO hybrid system in long-term operation, the performance and fouling characteristics of the PFFO-RO hybrid system in real wastewater treatment, and seawater desalination over two months were investigated. At the end of the process, organic compounds, mainly humic substances such as humic and fulvic acid, accounted for 89.32% and 91.46% of the foulant on the PFFO and RO membranes, respectively. Moreover, organic compounds with molecular weights over 500 Da were removed by PFFO, and those over 60 Dalton were removed by RO. This study can provide the information about maintenance of the PFFO-RO hybrid process in wastewater treatment.
68. 题目: Bio-efficacy of imidazolinones in weed control in a tropical paddy soil amended with optimized agrowaste-derived biochars
作者: Saba Yavari, Hesam Kamyab, Teh Sabariah Binti Abd Manan, Shreeshivadasan Chelliapan, Robabeh Asadpour, Sara Yavari, Nasiman Bin Sapari, Lavania Baloo, Azwadi Bin Che Sidik, Irina Kirpichnikova
摘要: Biochar is a black carbon sorbent that has the ability to stabilize organic substances in soil and, therefore, the potential to reduce their bio-availability. This sustainable material can be produced from locally-available agro wastes. The present study, for the first time, investigated the effects of biochars produced from oil palm empty fruit bunches (EFB) and rice husk (RH) on the efficiency of imazapic and imazapyr (two polar members of imidazolinone herbicides) as well as Onduty®, a mixture of them. It was executed in a Malaysian paddy field soil during a 30-day greenhouse experiment. The presence of optimized EFB and RH biochars in the heavy soil generally increases weed seeds germination and plants growth due to stabilization of the herbicides. The effect of EFB biochar was found higher than RH biochar having a higher affinity to the herbicides. An increase in the biochars application rates enhanced their effects as a soil modifier. Differences were more significant in the higher herbicides doses. Efficacies of all the herbicides were generally decreased in the biochar-amended soils. In the presence of 0.5% biochar in soil, the GR50 values for all herbicides were almost similar to biochar-free soil. In a 1.0% biochar-soil mixture, GR50 values of the herbicides increased by about 1.5 times. Bio-efficacies of the herbicides decreased by around 2.0 times as the biochar application rate enhanced to 2.0%. The greatest GR50 values were obtained in the presence of 4.0% biochar in the soils and were about 7.0–8.5 folds, indicating the high capability of amended soil in the stabilization of the herbicides. The findings of this study can help to reduce imidazolinones’ pollution and, in this way, prevent the threats of their residues to the environment.
69. 题目: Release of dissolved organic carbon from biochar and formation of humic-like component during photoreaction: Effects of Ca2+ and pH
期刊: Water Research
作者: Minmin Liu, Zhiying Zhao, Qingxuan Lu, Wenzheng Yu
摘要: The photochemical reactivity of dissolved organic carbon from biochar (DBC) was higher than dissolved organic matter (DOM), but the photo-transformation of DBC in the presence of DOM under various conditions are poorly understood. Here, we studied the effects of Ca2+ and pH on the photo-induced changes in the optical and structural properties of DOM in source water with biochar. During DBC photobleaching, the DBC released from bulk DBC while the humic-like component formed. The release of DBC and the formation of humic-like component were inhibited by the presence of Ca2+ attributed to the inhibition of triplet excited state of DOM (3DOM*) and singlet oxygen (1O2) generation. Moreover, the 3DOM* yield increased while the 1O2 generation decreased as pH decreased from neutral, resulting in the increased formation of humic-like component and decreased release of DBC. The characterizations of ultrafiltration-isolated colloidal DOM after irradiation showed that hydrophilicity and the colloidal size of released DBC decreased in the presence of Ca2+. Additionally, the colloidal size of released DBC decreased while the hydrophilicity of DBC enhanced with increasing pH from neutral. This study not only gives insight into the DBC photo-transformation in the presence of DOM under various conditions but also reveals the influence of DBC on the variation of DOM properties during irradiation.
70. 题目: How Particle Size Influences Oxidation of Ancient Organic Matter during Weathering of Black Shale
期刊: ACS Earth and Space Chemistry
作者: Xin Gu, Susan L Brantley
摘要: Weathering continuously converts rock to regolith at Earth’s surface while regulating the atmospheric concentrations of CO2 and O2. Shale weathering is of particular interest because shale, the most abundant rock type exposed on continents, stores much of the ancient organic carbon (OCpetro) buried in rocks. Using geochemical and mineralogical analysis combined with neutron scattering and imaging, we investigated the weathering profile of OCpetro in saprock in a black shale (Marcellus Formation) in the Ridge and Valley Appalachians in Pennsylvania, U.S.A. Consistent with the low erosion rate of the landscape, we discovered that Marcellus is completely depleted in carbonate, plagioclase, and pyrite in saprock below the soil layer. On the contrary, only ∼60% of OCpetro was depleted in saprock. By comparing the pore structure of saprock to bedrock and samples combusted to remove organic matter (OM), we confirmed that the large particles of OM are preferentially depleted, leaving elongated pores of tens to hundreds of micrometers in length, while the smaller particulates of OM (ranging from ∼5 to ∼200 nm) are largely preserved during weathering. The retarded weathering of small OM particles is attributed to their close association with mineral surfaces in the shale matrix. The texture of OM in shale is underappreciated as an important factor that controls porosity generation and the weathering rate of OCpetro.
71. 题目: Impacts of nutrient addition on soil carbon and nitrogen stoichiometry and stability in globally-distributed grasslands
作者: Katherine S Rocci, Kaydee S Barker, Eric W Seabloom, Elizabeth T Borer, Sarah E Hobbie, Jonathan D Bakker, Andrew S MacDougall, Rebecca L McCulley, Joslin L Moore, Xavier Raynaud, Carly J Stevens, M Francesca Cotrufo
摘要: Global changes will modify future nutrient availability with implications for grassland biogeochemistry. Soil organic matter (SOM) is central to grasslands for both provision of nutrients and climate mitigation through carbon (C) storage. While we know that C and nitrogen (N) in SOM can be influenced by greater nutrient availability, we lack understanding of nutrient effects on C and N coupling and stability in soil. Different SOM fractions have different functional relevance and mean residence times, i.e., mineral-associated organic matter (MAOM) has a higher mean residence time than particulate organic matter (POM). By separating effects of nutrient supply on the different SOM fractions, we can better evaluate changes in soil C and N coupling and stability and associated mechanisms. To this end, we studied responses of C and N ratios and distributions across POM and MAOM to 6–10 years of N, phosphorus (P), potassium and micronutrients (K+µ), and combined NPK+µ additions at 11 grassland sites spanning 3 continents and globally relevant environmental gradients in climate, plant growth, soil texture, and nutrient availability. We found addition of N and NPK+µ generally reduced C:N in MAOM and POM. However, at low fertility and at warm, sandy sites, nutrient addition promoted higher MAOM and POM C:N, respectively. Addition of NPK+µ also promoted C storage in POM relative to MAOM, and this was consistent across sites. Our results suggest that addition of macro- and micronutrients consistently decrease SOM stabilization, whereas responses of soil C:N stoichiometry were contingent on SOM fraction and environmental conditions.
72. 题目: Sources and transformations of nitrogen in an agricultural watershed on the Jianghan Plain, China: an integration of δ15N–NH4+, δ15N–NO3-, δ18O–NO3- and a Bayesian isotope mixing model
期刊: Applied Geochemistry
作者: Mingda Cao, Xijie Yin, Jie Zhang, Menggui Jin, Xin Huang
摘要: Due to the complexity of nitrate sources and transformation processes under extensive human activities and climate change, there are a great number of uncertainties associated with ascertaining nitrogen sources and transformations in agricultural watersheds. In this study, multiple isotopes of ammonium (δ15N–NH4+), nitrate (δ15N–NO3-, δ18O–NO3-), water (δ18O–H2O) and hydrogeochemical data were integrated to identify nitrogen sources and elucidate the mechanisms of nitrogen transformation in the Quanshui River watershed, a typical agricultural watershed in central China. The characteristics of nitrate nitrogen and oxygen isotopes, lower δ15N–NO3- values (<9.73‰), and the results from the Bayesian isotope mixing model showed that the main sources of nitrogen in the watershed were mostly ammonium fertilizers (AF), nitrate fertilizer (NF) and soil organic nitrogen (SON). In the fertilization season, the enrichment of δ15N–NH4+ and the negative correlation between δ15N–NH4+ and δ15N–NO3- indicated that the volatilization and partial nitrification of nitrate in chemical fertilizers were the main factors affecting nitrogen isotope changes in the water. Seasonal changes in δ15N–NH4+ and δ15N–NO3- values can provide more direct isotopic evidence for the occurrence of nitrification, which may provide more useful insights into nitrogen transformation in future studies. Seasonal variations in δ18O–NO3- can effectively indicate the impact of rainfall events on the nitrogen cycle.
73. 题目: Rare earth elements in surface lake sediments of Russian arctic: Natural and potential anthropogenic impact to their accumulation
期刊: Applied Geochemistry
作者: Z.I. Slukovskii, A.V. Guzeva, V.A. Dauvalter
摘要: Investigations of the rare earth elements (REEs) concentrations in surface sediments of small lakes in the Arctic zone of the Russian Federation are presented. The territories of Murmansk Region and the Republic of Karelia were used as key study areas. The sampling of 9 lake sediments was carried out. Inductively coupled plasma mass spectrometry (ICP-MS) method was used as a main approach to estimate total concentrations of REEs and heavy metals and content of their elements in different fractions, using sequential extraction method. The role of the natural landscapes factor (tundra, forest-tundra, taiga) in the process of REEs accumulation in lake sediments was evaluated in the course of the work. It was revealed that the highest median accumulation of REEs occurred in the sediments of lakes in the tundra zone, and the lowest median accumulation of REEs occurred in the lakes in the forest zone (taiga). The dynamics of the REEs accumulation in the lakes of the background (pristine) regions of the Arctic, as well as in the lakes of urbanized territories, is shown on the example of the cities of Murmansk Region. The analysis of the vertical distribution of REEs and heavy metals in the cores of sediments of the studied lakes showed that the anthropogenic factor plays an important role in the accumulation of REEs in urban water bodies. First of all, this is due to dust from construction, wear and tear of houses and road structures, and weathering of soils and quaternary deposits in urban areas. All urban lakes showed similarity between distribution of REEs and heavy metals in the sediments. The main fractions of REEs in the sediments of the lakes of the Arctic zone of Russia were determined. It was revealed that the residual phase of sediments and organic matter plays a significant role in the accumulation of REEs in surface sediments of the North of Russia. At the same time, mobile forms and phases of REEs associated with Fe and Mn oxides also did not play a large role in the accumulation of REEs in the sediments of lakes in Northwest Russia.
74. 题目: Adsorption of p-benzoquinone at low concentrations from aqueous media using biosolid-based activated carbon
期刊: Journal of Environmental Management
作者: Nina Ricci Nicomel, Loretta Y Li, Badr A Mohamed, Samia Syeoti Ramim
摘要: The toxic oxidation intermediate p-benzoquinone exists in aqueous environments at dilute concentrations above the fish-toxicity limit of 0.045 mg/L, affecting aquatic life. The reduction of this compound to the concentrations required to achieve safe discharge limits is challenging. In this study, the adsorptive removal of p-benzoquinone by a biosolid-based activated carbon (SBAC) was systematically investigated in batch experiments. The adsorption rate was rapid, and the bulk of p-benzoquinone adsorption occurred within 30 min. The maximum adsorption capacity of SBAC was estimated at 19.6 mg/g using the Langmuir isotherm model. Its adsorptivity was independent of temperature from 6 to 40 °C. The presence of 6 g/L of chloride and 500 mg/L of sulphate did not affect the removal of 1 mg/L p-benzoquinone, whereas 15 mg/L of humic acid media slightly decreased the p-benzoquinone removal from 87.0% to 83.2%. Diffusion, hydrophilic, and electrostatic interactions (i.e., dipole–dipole) govern the adsorption of p-benzoquinone and are influenced by the SBAC surface chemistry. Biosolid-based activated carbon can lower the residual p-benzoquinone to below the fish-toxicity limit of 0.045 mg/L within 1 h of sequential adsorption. Thus, biosolid-based activated carbon can effectively remove p-benzoquinone from aqueous environments; this is a waste-to-resource approach that addresses sustainability (waste disposal) and environmental protection (pollutant removal).
75. 题目: Positive feedback relationship between shrub encroachment and arbuscular mycorrhizal fungi in the Inner Mongolia grassland of northern China
期刊: Applied Soil Ecology
作者: Yun-Duo Zhao, Xia Hu, Peng-Yu Pan
摘要: Arbuscular mycorrhizal fungi (AMF) are soil microorganisms symbiotic with plants and play critical roles in the growth and survival of their hosts. However, the influence of shrub encroachment on AMF remains unclear. We analysed the soil microbial biomass of fungi, especially AMF, under interspace grass patches and shrub patches during the process of shrub encroachment using phospholipid fatty acid (PLFA) analysis. The results illustrated that the soil microbial biomass of AMF gradually increased under the shrub patches and gradually decreased under the interspace grass patches during the process of shrub encroachment. The most obvious change in the soil microbial biomass of AMF was found from moderately disturbed grassland to severely disturbed grassland under interspace grass patches and shrub patches. Soil nutrients, especially soil organic carbon (SOC), were found in greater amounts under the shrub patches than under the interspace grass patches. Shrub encroachment positively affected the microbial biomass of AMF by increasing the SOC content, and the increase in the microbial biomass of AMF increased the soil available phosphorus (AP) content and further promoted the development of shrub encroachment. There was a positive feedback relationship between shrub encroachment and AMF. This feedback mechanism was only applicable to AMF and was not found for other fungi. Our results highlight that there is a linkage between shrub encroachment and the microbial biomass of AMF, which explains the potential irreversibility of the transition from grass dominance to shrub dominance in the case of shrub encroachment.
76. 题目: Managing Fenton-treated sediment with biochar and sheep manure compost: Effects on the evolutionary characteristics of bacterial community
期刊: Journal of Environmental Management
作者: Biao Song, Eydhah Almatrafi, Fan Sang, Wenjun Wang, Chen Zhang, Maocai Shen, Chengyun Zhou, Xiang Tang, Guangming Zeng, Jilai Gong
摘要: Fenton oxidation is a widely used method for the fast and efficient treatment of contaminated sediment, but few studies have investigated the management of Fenton-treated sediment for resource utilization. In this study, the evolutionary characteristics of bacterial community composition in Fenton-treated riverine sediment were investigated using 16S rRNA gene sequencing after the incorporation of rice straw biochar and sheep manure compost. The Fenton treatment caused a decline in the relative abundance of Bacteroidetes from 39% to 8% on the 7th day, and using biochar and compost rapidly increased the relative abundance of Firmicutes from 13% to 61% and 57%, respectively. Applying 1.25 wt% biochar after the Fenton treatment contributed to high Shannon diversity indices of 4.80, 4.69, and 4.76 on the 7th, 28th, and 56th day, respectively. The reduced differences of Shannon indexes on the 56th day indicated that the bacterial diversity among different treatments tended to be similar over time. The genera Flavisolibacter and Bacillus were representatively detected on the 7th day in the untreated sediment and Fenton/biochar-treated sediment, respectively. The number of feature bacteria decreased significantly from 88 on the 7th day to 29 on the 56th day. The community functions for the carbon, nitrogen, and sulfur cycles were sensitive to the Fenton-treatment and the subsequent treatment with biochar and compost. This study may provide a useful reference for follow-up work on the remediation of contaminated sediment using advanced oxidation processes, and promote the development of resource utilization of amended sediment.
77. 题目: Adsorption effect and the removal mechanism of silicate composite biochar particles on cadmium in soil
作者: Shengnan Yuan, Jinyu Zhang, Zhongxin Tan
摘要: Ordinary biochar has the disadvantages of low strength and fragility, and it is difficult to be separated in heavy metal contaminated soil after the remediation process. In order to realize the recovery and reuse of biochar, we prepared silicate composite biochar (SCB) and the magnetic silicate composite biochar (MSCB) with consistent particle size and high hardness. As well as the passivation effect and mechanism of the material on cadmium in soil was also investigated. The results showed that: (1) The MSCB had good hydraulic properties and strong magnetism, which can be quickly separated from the soil under the condition of external magnetic field. (2) The MSCB can remove 30.32%–38.80% of cadmium in the soil after three times of “application-separation-desorption-reuse”, as well as the SCB can remove 28.30%–35.78% of cadmium from the soil. (3) The recovered SCB and MSCB had a certain mass loss, the mass loss rate of the biochar particles was in the range of 2.65%–4.90% after each time of recycling. (4) MSCB mainly immobilized cadmium ions through pore interception, complexation of oxygen-containin/iron-containin functional group and precipitation reaction.
78. 题目: Adsorption of fulvic acid on mesopore-rich activated carbon with high surface area
期刊: Science of The Total Environment
作者: Min Hu, Wenhao Wu, Daohui Lin, Kun Yang
摘要: The loss of dissolved organic matter (DOM), especially fulvic acid (FA), from soil by rainfall and runoff will reduce soil fertility and result in water pollution of DOM. Carbon materials including biochars (BCs) and activated carbons (ACs) are widely suggested for soil remediation and carbon immobilization. However, these suggested carbon materials are dominated by micropores, and largely limiting the adsorption capacity for FA. Therefore, a mesopore-rich activated carbon (KAC) with high surface area was prepared from bamboo chips to investigate the adsorption of FA. This KAC can adsorb FA more than ACs and BCs investigated in this study and reported in previous studies not only because of the high surface area (3108 m2/g), but also the higher mesopore volume proportion (57%). The negative pH effect on adsorption performance of KAC was weaker than that on AC and BC, because of the less polarity of KAC. Moreover, KAC was favorable to adsorb FA fractions with various molecular weights, higher aromaticity and higher polarity. This study indicated that KAC was a promising adsorbent for FA, and revealed the underlying adsorption mechanism of FA on KAC, which are helpful for the carbon immobilization and pollution control in soil.
79. 题目: Carbon storage in agricultural topsoils and subsoils is promoted by including temporary grasslands into the crop rotation
作者: Thomas Guillaume, David Makowski, Zamir Libohova, Saïd Elfouki, Mario Fontana, Jens Leifeld, Luca Bragazza, Sokrat Sinaj
摘要: Atmospheric C sequestration in agricultural soils is viewed as one of the most promising negative emission technologies currently available. Nonetheless, it remains unclear how strongly soil organic carbon (SOC) stocks respond to agricultural practices, especially for subsoil. Here, we assess the SOC storage potential in croplands and how the presence of temporary grasslands (TG) in the crop rotation affects SOC stocks. We developed a new approach to correct for bias in bulk density (BD) induced by sampling conditions and land-use effects with a data-driven model to predict the BD of fine soil (<2 mm) for reference condition. Using 54 permanent grassland and cropland sites with various proportions of TG from a monitoring network in Switzerland, we showed that SOC stock differences down to 50-cm depth between cropland and permanent grasslands (maximum: 3.0 ± 0.8 kg C m−2) depend on the TG proportion in the crop rotation, regardless of clay content and pH. An increase of the TG proportion by 10% would induce a SOC gain of 0.40 ± 0.13 kg C m−2. The responses of topsoil (0–20 cm) and subsoil (20–50 cm) SOC stocks to TG proportion were linear and equivalent. The effect of TG on SOC storage would have been underestimated by 58% without accounting for subsoil stocks response and by 16% without BD corrections. The conversion of all croplands to permanent grasslands in the study region would potentially store a quantity of SOC equivalent to the anthropogenic greenhouse gas emissions generated by the same region during one year. Although the potential of agricultural soils as negative emission technology is relatively modest compared to former expectations, the findings demonstrate the potential to manage SOC and its associated ecosystem services at large scales and down to deep soil layers.
80. 题目: Modified and pristine biochars for remediation of chromium contamination in soil and aquatic systems
作者: Ali El-Naggar, Ahmed Mosa, Naveed Ahmed, Nabeel Khan Niazi, Balal Yousaf, Binoy Sarkar, Jörg Rinklebe, Yanjiang Cai, Scott X Chang
摘要: Chromium (Cr) contamination in soil and water poses high toxicity risks to organisms and threatens food and water security worldwide. Biochar has emerged as a promising material for cleaning up Cr contamination owing to biochar's strong capacity to immobilize Cr. This paper synthesizes information on biochar modification for the efficient remediation of Cr contamination in soil and water, and critically reviews mechanisms of Cr adsorption on pristine and modified biochars. Biochar modification methods include physical activation via ball milling or ultraviolet irradiation, chemical activation via magnetization, alkali/acid treatment, nano-fabrication or loading of reductive agents, and biological activation via integrating biochars with microorganisms and their metabolites. Modified biochars often have multi-fold enhancement in Cr adsorption/reduction capacity than pristine biochars. Iron (Fe)-supported magnetic biochars have the most promising Cr removal abilities with high reusability of the biochars. Pre-pyrolysis modification with Fe could load Fe3O4 micro-/nanoparticles on biochars, and increase the surface area and electrostatic attraction between chromate anions and biochar surfaces, and reduce Cr(VI) to Cr(III). Post-pyrolysis modification could enrich oxygen-containing functional groups such as C￼O and –OH on biochar surfaces and promote Cr reduction and adsorption. Future research directions for Cr mitigation using advanced biochar products are discussed in this review.