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17361. 题目: Mediation of rhodamine B photodegradation by biochar
文章编号: N20051706
期刊: Chemosphere
作者: Danping Wu, Fangfang Li, Quan Chen, Min Wu, Wenyan Duan, Qing Zhao, Bo Pan, Baoshan Xing
更新时间: 2020-05-17
摘要:

Significant degradation of organic contaminants in biochar sorption systems has recently been reported, demonstrating a promising potential application of biochar in pollution control. We hypothesized that the degradation of organic chemicals by biochar may be further enhanced under irradiation by UV light due to the photocatalytic activities of carbonaceous materials. Our results confirmed that UV conditions increased the degradation of rhodamine B (RhB) by up to three times compared to dark conditions. Washing biochar with ultrapure water further increased RhB photodegradation by up to ten times. This photodegradation increase was the highest for biochar produced at 1000 °C. HF treatment and the addition of biochar supernatant did not increase RhB photodegradation. Therefore, the biochar properties mediating RhB photodegradation may be related to solid particles, mostly the combination of graphite structures and organic functional groups. Based on XPS and FTIR analysis, we propose that the quinoid CO in biochar may play an essential role in RhB photodegradation. Further research on identifying the photoactive components of biochar will be fundamental for improved biochar manufacture and application.

17362. 题目: Advanced oxidation treatment of dissolved organic matter from wastewater treatment plant secondary effluent using scattering electrical reactor
文章编号: N20051705
期刊: Journal of Cleaner Production
作者: Hao Wang, Bingxu Quan, Guozhu Bo, Yaozong Zhang, Lu Liu, Jiansong Zhang, Xinyuan Zhang, Chunhui Zhang
更新时间: 2020-05-17
摘要:

In this study, scattering electrical reactor (SER) was applied to remove dissolved organic matter (DOM) from wastewater treatment plant secondary effluent (WTPSE), in order to investigate factors influencing removal effect including the electrolysis time, initial pH and current density, etc. The experiment results based on three-dimensional fluorescence spectrum showed that DOM from WTPSE consisted mainly of humic acids and soluble microbial metabolites which could be effectively decomposed through SER. Under the condition that initial pH was 6, current density was 12 mA/cm2, and the electrolysis time was 20 min, the removal rate of DOM could achieve 93.23%. The increase of degradation efficiency of DOM could be obtained by lowering initial pH. A function fitting model of SER was established, which could obviously simulate the relation between concentration of DOM and electrolysis time during the degradation of DOM. Infrared spectrum was applied to prove that the successful degradation of DOM could be explained by the appearance of O–H and the phenomenon that the anodes were corroded and dissolved during the process of electrolytic oxidation. The results also showed that the specific energy consumption of DOM degradation by Ru/Ir-coated electrodes was favorable, which was lower than the degradation by normal titanium electrodes.

17363. 题目: Influence of floc charge and related distribution mechanisms of humic substances on ultrafiltration membrane behavior
文章编号: N20051704
期刊: Journal of Membrane Science
作者: Siqi Wu, Xin Hua, Rui Miao, Baiwen Ma, Chengzhi Hu, Huijuan Liu, Jiuhui Qu
更新时间: 2020-05-17
摘要:

The integration of flocs with ultrafiltration (UF) membranes is a promising method to alleviate membrane fouling and reduce land use; however, the floc charge and related pollutant distribution mechanism in the floc-based layer, which are key issues in further improving membrane performance, have been given little attention up to this point. Herein, the UF membrane performance in the presence of differently charged floc layers and the corresponding humic acids (HA) distribution were investigated. The results indicated that the floc charge played an important role in UF membrane behavior due to the different HA distribution mechanisms. Owing to the electrostatic adsorption, most negatively charged HA molecules were relatively uniformly adsorbed inside the positively charged floc layer (pH < 8.5), and fewer HA molecules reached the membrane surface. The HA removal efficiency was as high as 92.5 ± 1.5% at a pH of 6, and the final J/J0 was 0.73. It has been shown that pore adsorption or blocking was mainly alleviated, and the proportion of the irreversible fouling was only 6.0 ± 2.4% at a pH of 6. In contrast, fewer HA molecules were intercepted inside the negatively charged floc layer (pH > 8.5), and they were mostly distributed at the top and bottom of the cake layer due to electrostatic repulsion. The HA removal efficiency significantly decreased to 32.4 ± 1.2%, while the final J/J0 increased to 0.78 at a pH of 9.5. Further experiments demonstrated that the cake-layer resistance was considerably alleviated, and the proportion of the reversible fouling was remarkably reduced to 49.5 ± 3.2% at a pH of 9.5. In addition, membrane fouling caused by large–molecular weight (MW) HA was easily alleviated by the positively charged floc layer, while that caused by small-MW HA was easily alleviated by the negatively charged one. These findings have significant potential applications in practical membrane-based treatments of drinking water.

17364. 题目: Role of biochar and organic substrates in enhancing the functional characteristics and microbial community in a saline soil
文章编号: N20051703
期刊: Journal of Environmental Management
作者: M.R.K. Manasa, Naveen Reddy Katukuri, Sree Sankar Darveekaran Nair, Yang Haojie, Zhiman Yang, Rong bo Guo
更新时间: 2020-05-17
摘要:

In sustaining the soil quality, soil salinization has become a major challenge due to the increasing salinity rate of 10% annually. Despite, the serious concerns, the influence of soil amendments on microbial communities and its related attributes have limited findings. Therefore, the present study aims to investigate the potential of three various biochars, digestate (DI), and its compost (COM) in reclamation of saline soil under closed ecosystem. The decrease in the pH was displayed by lignite char, and electrical conductivity by lignite char plus COM addition among all the treatments. The subside in Na +, with a significant rise in K +, was exhibited in soils amended with DI plus DI biochar as a combined ameliorate over control. The negative priming effects on native soil organic carbon (nSOC) due to the decreased substrate bioavailability, in corn straw and DI biochars ameliorates were noted. The urease and alkaline phosphatase activity were pronounced higher in COM. However, the catalase and fluorescein diacetate activity were greater in lignite char plus DI and COM respectively. The co-addition of biochar and organic substrates shifted microbial community, is in correspondence with the relative abundance of the phylum. Overall, the abundance of Firmicutes and Actinobacteria was higher in soils under a combination of lignite char with DI and COM respectively. Likely, the abundance of Euryarchaeota was dominant in the co-application of corn straw biochar and DI. Redundancy analysis revealed the intactness between bacterial genera and their metabolisms with K +, and Mg 2+. PICRUSt disclosed the enhanced metabolic functions in soil with amalgam of DI and its biochar. The findings showed that the application of DI and its biochar mixture, as an amendment could be a better approach in the long-term reclamation of saline soil.

17365. 题目: Application of predictor variables in spatial quantification of soil organic carbon and total nitrogen using regression kriging in the North Kashmir forest Himalayas
文章编号: N20051702
期刊: Catena
作者: S.A. Bangroo, G.R. Najar, Ephraim Achin, Phuong N. Truong
更新时间: 2020-05-17
摘要:

Soil organic carbon (SOC) and total soil nitrogen (TSN) are the critical indices of soil fertility and the biogeochemical cycle. Distribution and variation of SOC and TSN in space are central to climate change and sustainable soil management studies. Little research on spatial prediction of SOC and TSN based on geostatistical techniques employing secondary variables (sampling location) and auxiliary information (topographic factors and type of vegetation) has been conducted globally and under the Himalayas in particular. In this study, 96 soil samples of 0–20 cm depths were taken from the forest area of North Kashmir Himalayas. The effect of topographic factors-elevation, slope, compound topographic index (CTI), stream power index (SPI), sediment transport index (STI), and normalized difference vegetation index (NDVI) on SOC and TSN spatial distribution were studied using regression kriging. Results indicate that regression kriging is a better predictor of SOC and TSN spatial distribution by 97.3% and 96.4% respectively than ordinary kriging with residuals moderately auto-correlated. Semi-variogram test indicated that elevation, slope, and NDVI are major factors driving SOC and TSN spatial variation. The negative correlation of topographic elevation and slope with the spatial distribution of SOC and TSN reveals better stabilization of SOC and TSN at lower degrees of slope and lower altitudes. Our study suggests that regression kriging at greater scale can provide the best estimations in a relatively uniform ecosystem provided there is a significant correlation between auxiliary variables and the SOC and TSN contents with residuals spatially auto-correlated.

17366. 题目: Response of soil phosphorus fractions and fluxes to different vegetation restoration types in a subtropical mountain ecosystem
文章编号: N20051701
期刊: Catena
作者: Denggao Fu, Xiaoni Wu, Changqun Duan, David R. Chadwick, Davey L. Jones
更新时间: 2020-05-17
摘要:

Soil phosphorus (P) improvement is one of the important aims of vegetation restoration. However, the effects of different vegetation restoration types on soil P cycling and the underlying mechanisms remain unclear. Together with vegetation structure and soil properties, we measured the soil P fractions and P transformation rates to evaluate the characteristics of ecologically relevant soil P fraction distributions and their dynamics for the most common vegetation restoration types in a subtropical mountain ecosystem (i.e., PF, Pinus forest; EF, Eucalyptus forest; SL, shrubland; and NSF, natural secondary forest). We found that water-extractable inorganic P (Pi), organic P (Po), and acid phosphatase activity (APA) were significantly higher in NSF than those in the other vegetation types (P < 0.01), together with the highest gross P mineralization rate (Pmin) and net P immobilization rate (Pimm), suggesting biological processes played a more important role in soil P cycling in the NSF. In contrast, the soil showed the lowest values of Pmin, Pimm, and APA in the EF compared to NSF and PF (P < 0.05), together with the highest P loss and the higher net P solubilization rate (Psol), indicating the greater importance of soil geochemical processes. Compared with the NSF and EF, geochemical and biological processes co-regulated soil P cycling in the PF and SL. However, the soil in the PF displayed higher P fluxes (Pmin, Pimm, Psol, and P loss) than those in the SL (P < 0.05), suggesting the soil had higher P flux magnitudes in the PF. Results of correlation analyses showed that the soil microbial community structure and activity played a more important role than plant community attributes and soil physicochemical properties in soil P fraction distribution and fluxes. In conclusion, soil P fraction distributions and their fluxes can be significantly influenced by vegetation restoration types. Land management strategies focusing on restoration of the soil microbial community may enhance soil P cycling and improve soil quality.

17367. 题目: Dissolved organic matter modified magnetic carbon nanotubes enhance the bioremediation of azo dyes and Cr( vi )
文章编号: N20051613
期刊: Environmental Science: Water Research & Technology
作者: Caiwen He, Lipeng Gu, Huan He, Zhe Zhang, Xiaoxia Wang, Fengxia Han, Bin Huang, Xuejun Pan
更新时间: 2020-05-16
摘要: Dissolved organic matter and Fe(III) species can serve as electron shuttles in the bioreduction of various pollutants in water treatment, but their residuals are also regarded as contaminants. Herein, immobilization of dissolved organics and Fe on carbon nanotubes still possess electron transfer capacity. Meanwhile, it could also lessen secondary pollution caused by residual DOM and Fe in bioreduction. In this study, anthraquinone-2-sulfonic acid (AQS) or humic acids were immobilized together with Fe3O4 on carbon nanotubes. The morphologies, structures and functional groups of the resulting materials were characterized. Nanotubes bearing AQS or humic acids both demonstrated high Cr(VI) and methyl orange reduction effectiveness at pH 8.0. The Cr(VI) and methyl orange were reduced by capturing electrons from microbial metabolism, with the DOMox/DOMred and Fe(III)/Fe(II) cycles promoting the process. The nanotube catalysts showed excellent stability and reusability. This study provided an innovative method for simultaneous bioremediation of Cr(VI) and methyl orange dye in wastewater.

17368. 题目: Soil quality and soil organic carbon storage in abandoned agricultural lands: effects of revegetation processes in a Mediterranean mid‐mountain area
文章编号: N20051612
期刊: Land Degradation and Development
作者: T. Lasanta, P. Sánchez‐Navarrete, L.M. Medrano‐Moreno, M. Khorchani, E. Nadal‐Romero
更新时间: 2020-05-16
摘要:

Land abandonment followed by natural revegetation constitutes the main land use change in the Mediterranean mountains, affecting soil quality and soil organic carbon (SOC) stocks; however, there are few studies analysing the effects of cropland abandonment in soils in mid‐mountains. In the Leza Valley (Spain), 43.2% of the area was cultivated but abandoned throughout the 20th‐century. Natural revegetation gave rise to five land uses (LULCs): pastures (5‐years), shrubs (Cistus laurifolius, 20‐35‐years), bushes (Juniperus communis, 35‐50‐years), young forests (Quercus pyrenaica) and old forests (>70‐years). The aim of this research was to study the effects of natural revegetation of abandoned fields on physico‐chemical soil quality and SOC in various LULCs. In each of the LULCs, soil samples were collected every 10 cm, down to 40 cm depth, at three points, with a total of 60 samples being analysed (12 per LULC). In addition, plant species inventories were carried out. The results indicated (i) significant differences in physico‐chemical soil quality between the first years of abandonment and forests; (ii) the SOC content increased with revegetation duration and decreased with increase in soil depth; (iii) the highest SOC and TN stocks were found in the first 10 cm; (iv) the results of the principal component analysis with all the data differentiate forests from shrubs, bushes and pastures. This study confirms the need to be aware of the effects of land abandonment and natural revegetation processes on the soil, in order to promote management strategies to preserve ecosystem services that agricultural marginal lands can provide.

17369. 题目: Oil palm cultivation enhances soil pH, electrical conductivity, concentrations of exchangeable calcium, magnesium and available sulphur and soil organic carbon content
文章编号: N20051611
期刊: Land Degradation and Development
作者: Sanjib Kumar Behera, Arvind Kumar Shukla, K. Suresh, K. Manorama, Ravi Kumar Mathur, Anil Kumar, P. Harinarayana, Chandra Prakash, Ajay Tripathi
更新时间: 2020-05-16
摘要:

The land area under oil palm (Elaeis guineensis Jacq.) cultivation (OPC) is on rise in different parts of world. Assessment of soil parameters of oil palm plantations (OPP) is very much essential to judge the sustainability of land use for maintaining soil fertility and avoiding land degradation. The effects of OPC in India on soil parameters are poorly understood. We, therefore, evaluated the impact of OPC over the years (by considering oil palm plantations of 6 years, 12 years and 18 years old) on soil properties, nutrient availability, soil organic carbon (SOC) pools and SOC stock in comparison to those parameters in adjacent fallow land (FL) of southern India. Soils of OPP recorded enhanced soil pH value, electrical conductivity, the concentrations of exchangeable calcium and magnesium and available sulphur and SOC content in 0–20, 20–40 and 40–60 cm depths of soil compared to those parameters in FL. Available phosphorus concentration in soil increased with plantation age revealing the need for rational phosphorus management. However, the concentration of available nitrogen, potassium, exchangeable calcium and magnesium and available sulphur and boron did not change with plantation age. The contents of SOC and very labile carbon were higher in surface soil layers of OPP than that in FL. Oil palm cultivation led to 20, 18 and 45% enhancement in SOC stock in 6, 12 and 18 years old OPP respectively, compared to SOC stock in FL indicating C sequestration due to OPC. The very labile and less labile C stock in FL, 6 years and 12 years OPP were similar; whereas, the values of these parameters were higher in 18 years old OPP. Positive correlation (p < 0.01) of SOC with very labile, labile and less labile carbon pools indicated their inter‐relatedness. This information will be utilized in devising rational nutrient management options for the existing as well as ensuing OPP due to variations in soil properties and available nutrients.

This article is protected by copyright. All rights reserved.

17370. 题目: Changes in soil organic carbon under perennial crops
文章编号: N20051610
期刊: Global Change Biology
作者: Alicia Ledo, Pete Smith, Ayalsew Zerihun, Jeanette Whitaker, José Luis Vicente‐Vicente, Zhangcai Qin, Niall P. McNamara, Yuri L. Zinn, Mireia Llorente, Mark Liebig, Matthias Kuhnert, Marta Dondini, Axel Don, Eugenio Diaz‐Pines, Ashim Datta, Haakon Bakka, Eduardo Aguilera, Jon Hillier
更新时间: 2020-05-16
摘要:

This study evaluates the dynamics of soil organic carbon (SOC) under perennial crops across the globe. It quantifies the effect of change from annual to perennial crops and the subsequent temporal changes in SOC stocks during the perennial crop cycle. It also presents an empirical model to estimate changes in the SOC content under crops as a function of time, land use, and site characteristics. We used a harmonized global dataset containing paired‐comparison empirical values of SOC and different types of perennial crops (perennial grasses, palms, and woody plants) with different end uses: bioenergy, food, other bio‐products, and short rotation coppice. Salient outcomes include: a 20‐year period encompassing a change from annual to perennial crops led to an average 20% increase in SOC at 0–30 cm (6.0 ± 4.6 Mg/ha gain) and a total 10% increase over the 0–100 cm soil profile (5.7 ± 10.9 Mg/ha). A change from natural pasture to perennial crop decreased SOC stocks by 1% over 0–30 cm (−2.5 ± 4.2 Mg/ha) and 10% over 0–100 cm (−13.6 ± 8.9 Mg/ha). The effect of a land use change from forest to perennial crops did not show significant impacts, probably due to the limited number of plots; but the data indicated that while a 2% increase in SOC was observed at 0–30 cm (16.81 ± 55.1 Mg/ha), a decrease in 24% was observed at 30–100 cm (−40.1 ± 16.8 Mg/ha). Perennial crops generally accumulate SOC through time, especially woody crops; and temperature was the main driver explaining differences in SOC dynamics, followed by crop age, soil bulk density, clay content, and depth. We present empirical evidence showing that the FAO perennialization strategy is reasonable, underscoring the role of perennial crops as a useful component of climate change mitigation strategies.

17371. 题目: Redox reactions of iron and manganese oxides in complex systems
文章编号: N20051609
期刊: Frontiers of Environmental Science & Engineering
作者: Jianzhi Huang, Huichun Zhang
更新时间: 2020-05-16
摘要: Conspectus: Redox reactions of Fe- and Mn-oxides play important roles in the fate and transformation of many contaminants in natural environments. Due to experimental and analytical challenges associated with complex environments, there has been a limited understanding of the reaction kinetics and mechanisms in actual environmental systems, and most of the studies so far have only focused on simple model systems. To bridge the gap between simple model systems and complex environmental systems, it is necessary to increase the complexity of model systems and examine both the involved interaction mechanisms and how the interactions affected contaminant transformation. In this Account, we primarily focused on (1) the oxidative reactivity of Mn- and Fe-oxides and (2) the reductive reactivity of Fe(II)/iron oxides in complex model systems toward contaminant degradation. The effects of common metal ions such as Mn2+, Ca2+, Ni2+, Cr3+ and Cu2+, ligands such as small anionic ligands and natural organic matter (NOM), and second metal oxides such as Al, Si and Ti oxides on the redox reactivity of the systems are briefly summarized.

17372. 题目: Pilot-scale coagulation of organic and inorganic impurities: Mechanisms, role of particle concentration and scale effects
文章编号: N20051608
期刊: Journal of Environmental Chemical Engineering
作者: Kanika Saxena, Urmila Brighu, Aditya Choudhary
更新时间: 2020-05-16
摘要:

The intrusion of natural organic matter in the surface waters has impeded the dosing approaches in the realm of coagulation-flocculation. Scaling up bench-scale coagulant doses to pilot or full-scale systems generally results in decreased system efficiency. In this study, the pilot-scale reactors of Sludge blanket clarifier (SBC) and Conventional clariflocculator (CC), as well as jar test data, are compared for the treatment of synthetic waters (prepared by kaolin and humic acid) at high alkalinity by using poly aluminium chloride (PACl). The turbidity removal for CC and SBC was 43–84 % and 20–81 %; the TOC removal was 20–83 % and 11–84 %; the DOC removal was 27–87 % and 38–92 %; and the UV254 removal was 72–89 % and 75–91 % respectively. pH, alkalinity and zeta potential were analysed to understand the process mechanisms. Adsorption models of Langmuir, Freundlich, BET and Temkin isotherms were compared to further validate removal mechanisms. For SBC, the R2 and RMSE (Root mean square error) values suggested BET model at lower turbidity and Temkin model at higher turbidities, indicating physical adsorption at lower turbidity followed by significant humic acid-kaolin interactions at high turbidity. For CC, the dominant mechanism was physical and chemical adsorption which was monolayer at lower turbidity and multilayer at higher turbidity. The charge neutralization was dominant in CC, unlike SBC. The sludge collected in the pilot plants was analysed by FTIR for linking chemical interactions to the mechanisms of removal. The FTIR data revealed the presence of Al(OH)3 and aromatics suggesting dominant removal by adsorption and entrapment.

17373. 题目: Statistical Design of Experiments for Purification of Vanillin from Commercial Lignin using Ion Exchange
文章编号: N20051607
期刊: Green Chemistry
作者: Shihong Liu, Lalitendu Das, David N. Blauch, Charlie Veronee, Chang Dou, John Gladden, Ning Sun, Aaron M Socha
更新时间: 2020-05-16
摘要: Lignin is a complex polyphenolic substance that collectively represents the largest renewable source of aromatic carbon on Earth. Despite low yield and purity from depolymerized lignin, bio-derived vanillin (4-hydroxy-3-methoxybenzaldehyde) is a desirable molecule in the food/beverage and fragrance industries. To maximize vanillin yield from commercially-available softwood lignin, a series of oxidation reactions were conducted using a Box-Behnken statistical design. By varying time, temperature and O2 pressure, optimal conditions were selected using the Response Surface Method, and a maximum vanillin yield of 5.3 wt % was achieved. Flash chromatography of depolymerized lignin was investigated by comparing anion exchange and reversed-phase resins and fractions were characterized by GC-MS, GPC-HPLC, FT-IR and NMR. Anion exchange separations using 1M NaCl as the sole mobile phase reached a vanillin purity of 55 wt %. Lastly, the vanillin mixture was reacted via reductive amination, and facile acid-base work up led to the formation of 4-((diethylamino)methyl)-2-methoxyphenol at 94.3 wt % purity. The aminophenol is an intermediate in the synthesis of pharmaceutical agents, ionic liquids and benzalkonium salts.

17374. 题目: Combined biochar and nitrogen application stimulates enzyme activity and root plasticity
文章编号: N20051606
期刊: Science of the Total Environment
作者: Xiaona Song, Bahar S. Razavi, Bernard Ludwig, Kazem Zamanian, Huadong Zang, Yakov Kuzyakov, Michaela A. Dippold, Anna Gunina
更新时间: 2020-05-16
摘要:

Biochar (BC) and nitrogen (N) fertilizers are frequently applied to improve soil properties and increase crop productivity. Nonetheless, our mechanistic understanding of plant-soil interactions under single or combined application of BC and N remains incomplete. For the first time, we applied a split-root system to evaluate how BC or N contributes to the changes in soil enzyme activities, N and phosphorus (P) cycling as well as root plasticity. Left and right parts of rhizoboxes were filled with silty-clay loamy soil amended with BC (15 g kg−1 soil, from wheat straw, 300 °C), N (0.05 g KNO3-N kg−1 soil) or a control (no amendments), resulting in the following combinations: BC/Control, N/Control, BC/N. Soil enzyme activities, available N and P, root morphology and plant biomass were analyzed after plant harvest.

Plant biomass (shoot + root) ranged from 0.56 g pot−1 (BC/Control) to 0.91 g pot−1 (BC/N). The decreased soil bulk density and increased P availability in the BC compartment (BC/Control and BC/N) stimulated root length by 1.4–1.8 times – an effect that was independent of N availability in the same rhizobox. Biochar stimulated activities of β-glucosidase and leucine aminopeptidase (by 33–39%) compared to N due to the coupling of C, N and P cycles in BC/N treated soil. Nitrogen fertilization also increased β-glucosidase activity compared to the unfertilized control, whereas root elongation remained unaffected. Thus, the combined application of BC/N had more efficient benefits for plant growth than BC or N alone. This is linked with i) the stimulation of enzyme activities at the BC locations to reduce N limitation for both microorganisms and plants, and ii) an increase of fine root production to improve N uptake efficiency. Thus, combined BC/N application is potentially especially sustainable to overcome nutrient limitation as well as to maintain crop productivity because it accelerates root-microbial interactions.

17375. 题目: Changes in nutrient balance, environmental effects, and green development after returning farmland to forests: A case study in Ningxia, China
文章编号: N20051605
期刊: Science of the Total Environment
作者: Ziyan Li, Xiting Sun, Zuhui Huang, Xuechen Zhang, Zhaohui Wang, Shiqing Li, Wei Zheng, Bingnian Zhai
更新时间: 2020-05-16
摘要:

Returning sloping farmland (>25°) to forest/grassland (RFTF) is an effective ecological measure for soil and water conservation. However, changes in nutrient cycles and green development are still unclear. Ningxia, in Northwestern China, began to implement RFTF in 2000. Here, we used the NUFER model to calculate the input and loss of nitrogen and phosphorus, utilization efficiency, production and consumption at food-chain scale in Ningxia for the period 1985–2015. Five aspects comprised the evaluation of green development: society, economy, resources, environment, and productivity. Results showed that forest coverage rate increased from 7.74% to 33.2%, while cropping area decreased by 6.6%. NH3 loss increased from 53,000 to 83,000 tons (56%), N2O increased from 1200 to 2300 tons (92%) and leaching loss from 18,000 to 62,000 tons (240%). Phosphorus leaching loss increased from 13,000 to 35,000 tons (130%). The environmental cost of food nitrogen per unit of production decreased from 8 to 6.7 kg/kg (19.4%). Nitrogen and phosphorus use efficiencies decreased by 4.8% and 58% in crops-animal systems, respectively, but increased by 652% and 430% in animal husbandry systems. The proportion of animal protein production increased from 18.3% to 39.0% (113%). The major source of organic waste was livestock and poultry manure and urine (70%). Indicators for achieving green development level increased from 14 to 18 (14.7%). Improving the level of scientific and technological management of aquaculture system, increasing the proportion of organic matter returned to farmlands, and paying attention to the combination of planting and breeding will effectively promote future cycling efficiency of nitrogen and phosphorus in the food chain, and the sustainability of agriculture towards green development.

17376. 题目: Leaching losses of dissolved organic carbon and nitrogen from agricultural soils in the upper US Midwest
文章编号: N20051604
期刊: Science of the Total Environment
作者: Mir Zaman Hussain, G. Philip Robertson, Bruno Basso, Stephen K. Hamilton
更新时间: 2020-05-16
摘要:

Leaching losses of dissolved organic carbon (DOC) and nitrogen (DON) from agricultural systems are important to water quality and carbon and nutrient balances but are rarely reported; the few available studies suggest linkages to litter production (DOC) and nitrogen fertilization (DON). In this study we examine the leaching of DOC, DON, NO3, and NH4+ from no-till corn (maize) and perennial bioenergy crops (switchgrass, miscanthus, native grasses, restored prairie, and poplar) grown between 2009 and 2016 in a replicated field experiment in the upper Midwest U.S. Leaching was estimated from concentrations in soil water and modeled drainage (percolation) rates. DOC leaching rates (kg ha−1 yr−1) and volume-weighted mean concentrations (mg L−1) among cropping systems averaged 15.4 and 4.6, respectively; N fertilization had no effect and poplar lost the most DOC (21.8 and 6.9, respectively). DON leaching rates (kg ha−1 yr−1) and volume-weighted mean concentrations (mg L−1) under corn (the most heavily N-fertilized crop) averaged 4.5 and 1.0, respectively, which was higher than perennial grasses (mean: 1.5 and 0.5, respectively) and poplar (1.6 and 0.5, respectively). NO3 comprised the majority of total N leaching in all systems (59–92%). Average NO3 leaching (kg N ha−1 yr−1) under corn (35.3) was higher than perennial grasses (5.9) and poplar (7.2). NH4+ concentrations in soil water from all cropping systems were relatively low (<0.07 mg N L−1). Perennial crops leached more NO3 in the first few years after planting, and markedly less after. Among the fertilized crops, the leached N represented 14–38% of the added N over the study period; poplar lost the greatest proportion (38%) and corn was intermediate (23%). Requiring only one third or less of the N fertilization compared to corn, perennial bioenergy crops can substantially reduce N leaching and consequent movement into aquifers and surface waters.

17377. 题目: Phosphorus speciation during anaerobic digestion and subsequent solid/liquid separation
文章编号: N20051603
期刊: Science of the Total Environment
作者: Stefania Mazzini, Gigliola Borgonovo, Leonardo Scaglioni, Floriana Bedussi, Giuliana D'Imporzano, Fulvia Tambone, Fabrizio Adani
更新时间: 2020-05-16
摘要:

This study aims to investigate the effect of anaerobic digestion (AD) on P species and how the different species are distributed in the digestate and digestate fractions, i.e. liquid and solid fractions. To do so, six full scale AD plants were used in this work and representative biomass samples were collected for investigation. P fractionation proceeded by adopting fractionation protocols consisting in step-by-step extraction with different solvents, (i.e. NaHCO3, HCl and NaOH-EDTA). Subsequently P species in the different fractions were identified by using 31P NMR. On average, AD did not substantially affect P speciation that depended on the P-fraction content of feeds. A high NaHCO3 fraction content in the ingestate determined, also, a high content of this fraction in the digestate, with consequently lower contents of both P-HCl and P-NaOH-EDTA, i.e. digestate P-fraction contents represented an inheritance of P speciation in the ingestate. A feed effect was observed in single plants. Highest pig/cow slurry content in the feeds seemed to decrease readily soluble P (extracted with NaHCO3) content and increased P associated with both organic matter and amorphous Fe/Al in the digestate. Again, using a large amount of digestate in the feed increased P-soluble content in the digestate. 31P NMR analyses revealed that inorganic P compounds dominated the spectra of all biomasses and fractions, with orthophosphate as the predominant species. When present, organic phosphorus compounds were typically represented by monophosphate esters, DNA and phospholipids, with a predominance of monophosphate esters.

17378. 题目: ROS-generation potential of Humic-like substances (HULIS) in ambient PM2.5 in urban Shanghai: Association with HULIS concentration and light absorbance
文章编号: N20051602
期刊: Chemosphere
作者: Xiaoya Xu, Xiaohui Lu, Xiang Li, Yaxi Liu, Xiaofei Wang, Hong Chen, Jianmin Chen, Xin Yang, Tzung-May Fu, Qianbiao Zhao, Qingyan Fu
更新时间: 2020-05-16
摘要:

Ambient fine particulate matter (PM2.5) can cause adverse health effects through the generation of reactive oxygen species (ROS) after inhalation. Humic-like substances (HULIS) are major constituents contributing to the ROS-generation potential in organic aerosols. In this study, PM2.5 samples in urban Shanghai during autumn and winter (2018–2019) were collected. Mass-normalized ·OH generation rate in surrogate lung fluid (SLF) was used to denote the intrinsic ROS-generation potential of PM2.5 or of the HULIS isolated from PM2.5. In this study, ROS-generation potential of PM2.5 decreased with increasing ambient PM2.5 concentration due to higher percentage of inorganic components in high PM2.5 event. Same trend was observed for the ROS-generation potential of unit mass of HULIS, which was higher when HULIS and PM2.5 concentrations were both relatively lower. The HULIS with high ROS-generation potential but low concentration (High-ROS/Low-Conc HULIS) were likely produced by the atmospheric aqueous-phase reactions during nighttime or under high relative humidity conditions, not from biomass burning emissions or the photochemical pollution products. The association between ROS-generation potential and light absorption properties of HULIS was studied as well. The High-ROS/Low-Conc HULIS also showed stronger light absorbance than the other HULIS. Our results implied the potentially important roles that HULIS species might play in atmospheric environment and human health even when the PM2.5 pollution is low.

17379. 题目: Adsorption of tetracycline hydrochloride onto ball-milled biochar: Governing factors and mechanisms
文章编号: N20051601
期刊: Chemosphere
作者: Wei Xiang, Yongshan Wan, Xueyang Zhang, Zhenzhen Tan, Tongtong Xia, Yulin Zheng, Bin Gao
更新时间: 2020-05-16
摘要:

Pristine and ball milled wheat stalk biochars pyrolysed at 300 °C, 450 °C, 600 °C were studied for tetracycline hydrochloride (TCH) adsorption from aqueous solution. Surface characteristics of ball milled biochar (BM-biochar) were significantly enhanced over their pristine counterparts. TCH adsorption occurred largely on external surface and by filling pores of biochars as evidenced by strong positive correlation between adsorption and external specific surface area (SSA), total pore volume, or mesoporous volume. A two-stage intra-particle diffusion model, limited by the TCH diffusion through the boundary liquid layer, well described TCH adsorption. Maximum TCH adsorption occurred at about pH = 6–8. While solution cations including Na+, K+ and Mg2+ subdued TCH adsorption as they competed for adsorption sites, Ca2+ promoted TCH adsorption due to formation of tetracycline-Ca2+ complexes. The best performing BM-biochar was the one pyrolysed at 600 °C with TCH adsorption amount of 84.54 mg/g. Therefore, this BM-biochar has the potential for TCH removal from aqueous solutions. And the research shed light on the management of organic contaminants in real wastewater by BM-biochar.

17380. 题目: Application of Orbitrap Mass Spectrometry to Investigate Seasonal Variations of Dissolved Organic Matter Composition in a Eutrophic Lake in Japan
文章编号: N20051513
期刊: Environmental Science: Water Research & Technology
作者: Yuthawong Vitharuch, Ikuro Kasuga, Futoshi Kurisu, Hiroaki Furumai
更新时间: 2020-05-15
摘要: Rapid urbanization induces organic pollution in closed water bodies and accelerates eutrophication. Dissolved organic matter (DOM), a major fraction of organic matter, causes various problems in water use. DOM sources in lakes are diverse. Moreover, DOM properties can be altered biologically and physicochemically during retention time. However, DOM in lakes consists of complex unknown substances. In the present study, high-resolution Orbitrap mass spectrometry (Orbitrap MS) was employed to determine the molecular-level composition of low-molecular-weight DOM in Lake Inba, the most polluted eutrophic lake in Japan. One-year monitoring demonstrated that the lake's DOM consisted of core components that were detected year-around and season-specific components. Although most DOM components extracted by solid phase extraction in the lake came from inflow rivers, lake-specific components were present, which could be associated with algal growth in the lake. Permanganate pretreatment was integrated with Orbitrap MS to screen for components contributing to dissolved chemical oxygen demand (DCODMn), an environmental parameter used in Japan to define the water quality of lakes and reservoirs. Results indicated that only minor and highly unsaturated components were responsible for DCODMn. With this approach, we were able to shed light on how the DOM composition in a eutrophic lake was shaped at molecular level, which cannot be achieved by conventional analysis.

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