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24761. 题目: Short-term effects of biochar and Bacillus pumilus TUAT-1 on the growth of forage rice and its associated soil microbial community and soil properties
文章编号: N20031701
期刊: Biology and Fertility of Soils
作者: Khin Thuzar Win, Keiki Okazaki, Naoko Ohkama-Ohtsu, Tadashi Yokoyama, Yoshinari Ohwaki
更新时间: 2020-03-17
摘要: The synergistic effects of biochar (BC) and plant growth-promoting bacteria inoculant on crop growth and microbial communities' composition in the rhizosphere and endorhizosphere (roots) of forage rice were examined under a short-term greenhouse condition. We performed in-pot experiments to evaluate the effects of BC and Bacillus pumilus strain TUAT-1 inoculant (Bio), both alone and in combination (BB), on the growth and microbial community of rhizosphere and roots in forage rice at 2 and 5 weeks after transplantation. At both growth stages, rice growth was improved by either BC or Bio alone. TUAT-1 was readily detected in rhizosphere with greater abundance following BB treatment than after Bio treatment alone. The bacterial communities of the rhizosphere, non-rhizosphere soil (un-planted bulk), and endorhizosphere of roots were determined using next-generation sequencing. Compared with the microbial community and diversity in the rhizosphere and endorhizosphere of roots, BC had greater effects on rhizosphere than on endorhizosphere, whereas Bio more effectively altered the microbial communities of the endorhizosphere layer of roots. Soil properties (pH and total N, exchangeable NH4-N, and K levels) were improved by either BC or Bio alone, suggesting that the changes of soil microbial communities might occur directly or indirectly as an effect of the alteration of soil physico-chemical properties. Overall, the result from this study suggests that biochar amendment and TUAT-1 inoculant have the potential to enhance growth and nutrient uptake in forage rice, and they depend on soil physico-chemical properties and the alteration of native microbial communities' composition.

24762. 题目: Persistence of native and bio-derived molecules of dissolved organic matters during simultaneous denitrification and methanogenesis for fresh waste leachate
文章编号: N20031607
期刊: Water Research
作者: Junjie Qiu, Fan Lü, Hua Zhang, Yulong Huang, Liming Shao, Pinjing He
更新时间: 2020-03-16
摘要: Biological treatment of wastewater always leaves plenty of refractory dissolved organic matters (DOM) in effluents, specifically for fresh waste leachate. Aiming at comprehending the production and removal of these compounds, this study investigated DOM transformation in a simultaneous denitrification and methanogenesis with activated sludge (SDM-AS) system with NO3−/NO2− backflow for raw fresh leachate. Chemical oxygen demand (COD) was reduced to 854 ± 120 mg/L from 63000 ± 470 mg/L, and total nitrogen (TN) decreased from 2500 ± 647 mg/L to 404 ± 75 mg/L, during an operation of 440 days. The SDM reactor was fed at organic loading rate of 6.70 kgCOD/(m3·d) to generate 2.52 L CH4/(L·d). Molecular information of leachate DOM was acquired by using ultra-performance liquid chromatography coupled with Orbitrap mass spectrometry. A DOM classification based on Venn diagram was proposed to divide leachate DOM into seven categories. It revealed that 76–84% of final effluent DOM stemmed from biological derivation. Posteriori non-target screening showed anthropogenic micropollutants, e.g. phosphate flame retardants and industrial agents, probably contributed to the remnant native inert DOM in the effluent at the levels of 5–200 μg/L. DOM Classification also showed a portion of bio-derived DOM can be completely removed by SDM-AS processes, while the rest bio-derived DOM can be partially removed depending on DOM nature and the recirculation ratio. The removal and production rate of specific bio-derived DOM in respective SDM and AS units theoretically satisfied a hyperbolical and dual relationship in terms of mass balance. The persistence of each DOM category was sorted. These results showed anaerobic degradation could be a promising approach to reduce aerobic bio-derived DOM.

24763. 题目: Sustainable energy from waste organic matters via efficient microbial processes
文章编号: N20031606
期刊: Science of The Total Environment
作者: Rajesh K. Srivastava, Nagaraj P. Shetti, Kakarla Raghava Reddy, Tejraj M. Aminabhavi
更新时间: 2020-03-16
摘要: This review emphasizes utilization of waste organic matters from water bodies and soil sources for sustainable energy development. These organic waste matters (including microplastics) from a variety of environmental sources have created a big challenge to utilize them for energy development for human needs, maintaining a cleaner environment and thereby, producing useful bioproducts (sustainable bioenergy or other primary metabolites). Anaerobic digestions as well as other effective wastewater treatment approaches are discussed. From the water bodies, waste organic matter reduction can be achieved by a reduction of chemical oxygen demand and biological oxygen demand after the waste treatment. Other forms of organic waste matter are available in the form of agro wastes or residues (stalk of wheat or rice, maize, corn etc.) due to crop cultivation, which are generally burnt into ashes. Such wastes can be utilized for bioenergy energy production, which would help for the reduction of climate changes or other toxic gases. Hydrogen, bioelectricity, ethanol, butanol, methane and algal diesel or other types of fuel sources would help to provide sustainable source of bioenergy that can be produced from these wastes via degradation by the biological processes. This review will discuss in depths about the sustainable nature of organic matters to produce clean energy via application of efficient biological methods to maintain a clean environment, thereby providing alternative options to fossil energy fuels.

24764. 题目: Kinetic effects of anaerobic staging and aeration rates on sequencing batch moving bed biofilm reactors: Carbon, nitrogen, and phosphorus treatment of cheese production wastewater
文章编号: N20031605
期刊: Chemosphere
作者: Alexandra Tsitouras, Onita Basu, Nour Al-Ghussain, Robert Delatolla
更新时间: 2020-03-16
摘要: The food and beverage industry produces wastewaters containing high concentrations of organic carbon and nutrients, which when discharged leads to eutrophication and algal blooms. Given recent stringencies in effluent regulations, industries are required to treat their wastewater on-site. There is a critical need for compact, high-rate, cost-effective wastewater technologies to treat industrial wastewaters, such as the sequencing batch moving bed biofilm reactor. The aim of this study is to investigate the potential and evaluate the performance of the sequencing batch moving bed biofilm reactor cycling between anaerobic and aerobic stages to treat high-strength food and beverage wastewaters. Specifically, this study focuses on the effects of anaerobic staging times and enhanced aeration on the removal of carbon, nitrogen, and phosphorous from cheese production wastewaters. Increasing anaerobic staging times was found to improve the removal rates of carbon beyond previously reported moving bed biofilm reactor results. Increasing the anaerobic stage however decreased the total nitrogen removal, with organic nitrogen undergoing ammonification during the anaerobic stage. This study demonstrates an optimum anaerobic staging time of 138 min; with a carbon removal rate of 31.1 g-sCOD·m−2d−1 and a nitrogen removal rate of 1.3 g-N·m−2d−1. Enhanced aeration was found to be detrimental to phosphorous removal, where a moderate aeration rate demonstrated a net total phosphorous removal of approximately 22 mg-P·l−1 with the phosphorous-content of the suspended solids being approximately 4%. Finally, the sequencing batch moving bed biofilm reactor shows potential for on-site treatment of carbon, nitrogen, and phosphorous from cheese production wastewater.

24765. 题目: Qualitative and quantitative analysis of source for organic carbon and nitrogen in sediments of rivers and lakes based on stable isotopes
文章编号: N20031604
期刊: Ecotoxicology and Environmental Safety
作者: Qingjun Guo, Chunyu Wang, Rongfei Wei, Guangxu Zhu, Meng Cui, Chukwunonso Peter Okolic
更新时间: 2020-03-16
摘要: Sediment is the most dominant reservoir of organic pollutants in the aquatic environment. Understanding carbon and nitrogen sources in sediments and factors that controls distribution enhances our understanding of biogeochemical cycles of carbon and nitrogen. Different end-members and surface sediments of rivers and sediments profiles of lakes were collected. The concentrations of TOC and TON and their δ13C and δ15N were studied for qualitative and quantitative analysis of natural and anthropogenic sources. The results show that TOC and TON concentrations of the sediments from rivers range from 0.63% to 10.83% and 0.06%–0.86%, respectively, indicating substantial great environmental risks in these rivers. The concentrations of TOC and TON for the four sediment profiles below the 5 cm, increase in the order of Miyun < Chuidiao < Qunming < Houhai, as influenced by their respective environment condition. Moreover, water quality was quite good and there was no risk of eutrophication in Miyun reservoir. δ13Corg and δ15Norg in surface sediments of the studied 18 rivers range from −27.2‰ to −24.9‰ and −2.2‰ to +10.9‰, respectively. Based on a simple δ13C-based end-member mixing and a C/N ratio model, organic matter in the surface sediments of these rivers were mainly derived from sewage and C3 plant. In addition, the sources of organic matter differed in each layer of the four sediment profiles. This study provides a reliable method for qualitative and quantitative identification of the source of organic matter in sediments, and offers theoretical basis for better management of rivers and lakes.

24766. 题目: Geochemical characterization of the depositional environment of Paleocene and Eocene sediments of the Tertiary Central Basin of Svalbard
文章编号: N20031603
期刊: Chemical Geology
作者: M. Doerner, U. Berner, M. Erdmann, T. Barth
更新时间: 2020-03-16
摘要: The Tertiary Central Basin (CTB) of Svalbard has been studied extensively in the past because it contains sediments from the Paleocene Eocene Thermal Maximum (PETM). Previous studies have found that a negative carbon isotopic extrusion (CIE) is presents without showing elevated concentration of organic carbon. In this study we extend the record of the CTB with a comprehensive inorganic and organic geochemical data set based on the sediments encountered in the research well BH 10–2008, comprising almost 1100 m of cored sediments. Major and trace elements analyses in combination with mineralogical, carbon isotopic, total organic carbon (TOC), and total sulphur measurements were used to reconstruct the depositional environments of the lower Paleocene Basilika Fm. up the Eocene Aspelintoppen Fm. Several depositional environments have been interpreted, which are consistent with the sedimentological interpretation of the respective well section. Back-calculation of the initial organic carbon concentration shows that bacterial sulphate reduction had a major impact on the persevered organic carbon inventory of the lower Basilika Fm. and of the Paleocene/Eocene transition section. Based on organic carbon loss introduced by bacterial decay, as well as measured isotopic composition, we estimate an initial isotopic composition of the evaluated sediments which helps to elucidate on the fate of labile organic matter and explains the unusually low organic carbon inventory of the Paleocene/Eocene transition sediments.

24767. 题目: Pasture degradation impact on soil carbon and nitrogen fractions of alpine meadow in a Tibetan permafrost region
文章编号: N20031602
期刊: Journal of Soils and Sediments
作者: Zi-Qiang Yuan, Qing-Bai Wu, Xin Song, Xiao-Jin Jiang, Si-Ru Gao, Qing-Feng Wang, Guo-Yu Li
更新时间: 2020-03-16
摘要: Purpose Knowledge of the effects of pasture degradation on soil organic carbon (SOC) and nitrogen (N) fractions in permafrost soils on the Tibetan Plateau is limited. The aims of this study were (1) to evaluate the changes in SOC and N contents in density fractions under Kobresia pasture due to degradation and (2) to explore the contributions of the changes of SOC and N in density fractions to the changes of SOC and N in whole soil. Materials and methods The impact of Kobresia pasture degradation on SOC and N fractions was investigated in the permafrost region of the Tibetan Plateau. A continuously degraded pasture was identified and classified into three categories of vegetation cover according to their degrees of degradation (i.e., vegetation cover decline from 90% ± 6.6% to 70% ± 8.3% and 45% ± 8.7%). The SOC and N fractions were separated by using the density separation method. Results and discussion The Kobresia pasture degradation significantly decreases SOC and N contents and stocks in soils. The SOC and N contents in the whole soil were positively correlated with the SOC and N contents in the light and heavy fractions (p < 0.001, respectively). The SOC and N contents were significantly correlated with soil pH and the contents of soil moisture, clay, silt, and sand. The ratio of SOC to total N in the whole soil was positively correlated with the ratio of SOC to N in heavy fractions (p < 0.001) rather than the ratio of SOC to N in light factions (p > 0.05). When pasture degraded from vegetation covers 90% to 45%, SOC stock at 0–40-cm soil layer decreased by 28.7% and N stock decreased by 39.2% in the whole soil; 56.6% and 47.6%, respectively, in the light fractions and 14.3% and 40.6%, respectively, in the heavy fractions. The depletion rates of N were higher than those of SOC in the heavy fractions and whole soil. At all sites, more than 80% of the SOC and N stocks were protected in heavy fractions. Conclusions These results indicate that a decoupling depletion of SOC and soil N appeared with the Kobresia pasture degradation in the permafrost region of the Tibetan Plateau. The Kobresia pasture degradation affects the SOC and N fractions differently and thus regulates soil carbon and N cycling in the permafrost soils on the Tibetan Plateau.

24768. 题目: The effect of post-pyrolysis treatment on waste biomass derived hydrochar
文章编号: N20031601
期刊: Waste Management
作者: L. Bahcivanji, G. Gascó, J. Paz-Ferreiro, A. Méndez
更新时间: 2020-03-16
摘要: Hydrochars are materials with a promising future, as their high carbon content and porosity renders them suitable for uses including peat substitutes, soil remediation and carbon adsorbent precursors. Combining hydrothermal carbonization and pyrolysis offers the prospect to provide advanced materials with a higher porosity and carbon content. This approach would mitigate drawbacks associated to hydrochars, including phytotoxicity. This research studied the influence of pyrolysis temperature and heating time on the resulting properties of chars made from hydrothermal carbonization of biomass wastes at 200 °C for 4 h and compared them to biochars that had not received any prior hydrothermal carbonization. Interestingly, hydrochar followed by pyrolysis was able to result in phytostimulation, while, when only pyrolysis was carried out, phytotoxicity was eliminated, but no phytostimulant effect was observed. In addition, the results indicated that the higher and longer the pyrolysis temperature (from 350 to 550 °C) and duration time (from 1 to 5 h), respectively, the more microporosity was generated, while phytotoxicity was reduced. In addition, aromaticity and thermal stability significantly increased with pyrolysis treatment. Consequently, hydrochars improve their properties and offer more potential for environmental applications after a pyrolysis post-treatment.

24769. 题目: Distribution and molecular chemodiversity of dissolved organic nitrogen in the vadose zone-groundwater system of a fluvial plain, northern China: Implications for understanding its loss pathway to groundwater
文章编号: N20031511
期刊: Science of The Total Environment
作者: Hui Nai, Jia Xin, Yang Liu, Xilai Zheng, Zhiwei Lin
更新时间: 2020-03-15
摘要: Nitrogen (N) pollution in groundwater has become a worldwide environmental geological issue due to the excessive N application into the vadose zone and furthered N leaching. Dissolved organic nitrogen (DON) are proposed as an overlooked pathway of N loss from agricultural systems to groundwater recently. Here, we collected soil (0–320 cm) and groundwater samples in a historic agricultural area to characterize the distribution and chemodiversity of DON in the vadose zone-groundwater system, and identified specific linkages between DON traits and the bacterial community. The results showed that DON and NO3−-N were the main forms of dissolved N in the vadose zone-groundwater system. The deep vadose zone (> 100 cm) was an important storage area for DON (44.9%), having implications for long-term groundwater quality degradation. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) revealed that the DON was dominated by condensed aromatics and lignins (57.2%) in the vadose zone, whereas amino sugars, protein, peptides and lignins (72.5%) were dominant in groundwater. By analyzing shared and ubiquitous DON molecular formulas detected among different layers, it was found that <2.52% of DONs could be leached from surface soil to groundwater directly, and most DONs went through biological conversion during the whole leaching path. It was identified that bacterial community played an important role in DONs transformation. The most active bacteria in the transformation were Nitrospira, Bacillus, and Sphingomonas and they tended to interact with DON of high N/C and H/C ratios, causing molecules with high unsaturation, high aromaticity and high oxidation to accumulate. The results would be helpful to elucidate DON occurrence in groundwater and track the key processes governing DON transport from the surface soil to groundwater.

24770. 题目: Humic-like acids from hydrochars: Study of the metal complexation properties compared with humic acids from anthropogenic soils using PARAFAC and time-resolved fluorescence
文章编号: N20031510
期刊: Science of The Total Environment
作者: João Vitor dos Santos, Lais Gomes Fregolente, Altair Benedito Moreira, Odair Pastor Ferreira, Stéphane Mounier, Bruno Viguier, Houssam Hajjoul, Márcia Cristina Bisinoti
更新时间: 2020-03-15
摘要: Humic acids (HA) play an important role in the distribution, toxicity, and bioavailability of metals in the environment. Humic-like acids (HLA) that simulate geochemical processes can be prepared by NaOH aqueous extraction from hydrochars produced by hydrothermal carbonization (HTC). HLA can exhibit properties such as those found in HA from soils, which are known for their ability to interact with inorganic and organic compounds. The molecular characteristics of HLA and HA help to explain the relationship between their molecular features and their interaction with metallic species. The aim of this study is to assess the molecular features of HA extracted from Terra Mulata (TM) and HLA from hydrochars as well as their interaction with metals by using Cu(II) ions as a model. The results from 13C NMR, elemental analysis, FTIR, and UV–Vis showed that HA are composed mostly of aromatic structures and oxygenated functional groups, whereas HLA showed a mutual contribution of aromatic and aliphatic structures as main constituents. The interactions of HA and HLA with Cu(II) ions were evaluated through fluorescence quenching, in which the density of complexing sites per gram of carbon for interaction was higher for HLA than for HA. Furthermore, the HLA showed similar values for stability constants, and higher than those found for other types of HA in the literature. In addition, the average lifetime in both humic extracts appeared to be independent of the copper addition, indicating that the main mechanism of interaction was static quenching with a non-fluorescent ground-state complex formation. Therefore, the HLA showed the ability to interact with Cu(II) ions, which suggests that their application can provide a new approach for remediation of contaminated areas.

24771. 题目: Synthesis of Fe-impregnated biochar from food waste for Selenium(Ⅵ) removal from aqueous solution through adsorption: Process optimization and assessment
文章编号: N20031509
期刊: Chemosphere
作者: Seung-Hee Hong, Fritz Ndumbe Lyonga, Jin-Kyu Kang, Eun-Jin Seo, Chang-Gu Lee, Sanghyun Jeong, Seong-Gu Hong, Seong-Jik Park
更新时间: 2020-03-15
摘要: Iron-impregnated food waste biochar (Fe-FWB) was synthesized for Se(Ⅵ) removal from aqueous solution. The effect and interactive effects of different parameters including pyrolysis time, temperature, and Fe concentration were explored using response surface methodology (RSM) to enhance conditions to achieve the highest Se(Ⅵ) removal using Fe-FWB. Pyrolysis time was not significant for Se(Ⅵ) adsorption capacity of Fe-FWB, but temperature and Fe concentration were found to be significant. The highest adsorption was achieved at 3.47 h and 495.0 °C with an Fe concentration of 0.44 M. Fe-FWB synthesized under optimum conditions were used to investigate the kinetic, equilibrium, and thermodynamic adsorption of Se(Ⅵ). Se(Ⅵ) adsorption reached equilibrium within 6 h, and both pseudo-second order and pseudo-first order models were suitable for describing kinetic Se(Ⅵ) adsorption. The Freundlich model was found to suitably fit the equilibrium adsorption data than the Langmuir model. The highest adsorption capacity of Fe-FWB for Se(Ⅵ) was 11.7 mg g−1. Se(Ⅵ) adsorption on Fe-FWB was endothermic and spontaneous. The enthalpy change for Se(Ⅵ) adsorption was 54.4 kJ mol−1, and the entropy change was negative at 15–35 °C. The increment of solution pH from 3 to 11 decreased the Se(Ⅵ) adsorption from 19.2 to 7.4 mg g−1. The impact of interfering anions on Se(Ⅵ) adsorption followed the lineup: HCO3− > HPO42− > SO42− > NO3−. When compared to some adsorbents, the adsorption capacity of Se(Ⅵ) onto Fe-FWB was comparable even at neutral pH and the Fe-FWB was granular. These results indicate that Fe-FWB has prospective application in the removal of Se(Ⅵ) from aqueous solutions.

24772. 题目: Enhancement of phosphate adsorption during mineral transformation of natural siderite induced by humic acid: Mechanism and application
文章编号: N20031508
期刊: Chemical Engineering Journal
作者: Bobo Xing, Mengzheng Ouyang, Nigel Graham, Wenzheng Yu
更新时间: 2020-03-15
摘要: The interfacial interactions between siderite, humic acid (HA), and phosphate, is critical to understand the transport of HA and phosphate in the environment. In this study, the influence of HA on the adsorption of phosphate by siderite not only includes competitive adsorption, but also includes indirectly facilitated adsorption. It was attributed to that humic acid as a representative natural organic matter possesses abundant carboxylic groups, which facilitate chelation between minerals and HA, and then the phosphate adsorption performance is affected. The experimental results concluded that three stages of the transformation from siderite to goethite under the action of HA can be divided. Firstly, chelation can be formed between HA and the ferrous ions from siderite, and it is favorable for the oxidation of Fe(II) by the O2 in water to form amorphous ferrihydrite; and then the ferrihydrite nano-particles were attached to the surface of goethite crystals; finally, the goethite crystal structure was formed by the structural rearrangement of ferrihydrite nano-particles. Meanwhile, the surface complex species of phosphate was formed on precipitate. It is revealed that the diprotonated bidentate binuclear complex is the main phosphate species when the HA concentration was 0.5 mg/L; as the HA concentration rose to 10 mg/L, the main phosphate species change to diprotonated monodentate mononuclear complex, which is attributed to the competitive adsorption of humic acid. We believe that these results are beneficial to guide the impact of HA for the biogeochemical cycling of phosphate, iron-bearing mineral transformation, as well as environmental remediation.

24773. 题目: Physicochemical mechanisms underlying soil and organic amendment effects on runoff P losses
文章编号: N20031507
期刊: Land Degradation & Development
作者: Amrakh I. Mamedov, Benayahu Bar‐Yosef, Irit Levkovich, Pinchas Fine, Avner Silber, Guy J. Levy
更新时间: 2020-03-15
摘要: Phosphorus depletion from cultivated lands by runoff is a significant contributor to soil chemical degradation. Our objective was to elucidate the mechanisms through which soil and organic matter amendments affect rain‐induced runoff P losses in Mediterranean soils. Clay, loam and loamy sand mixed with non‐composted activated sludge (AS), manure compost (MC), industrial humic acid (HA), orthophosphate (Pi) or inositol hexaphosphate (IHP), were subjected to six consecutive artificial rainstorms. Adding amendments significantly increased runoff available Pi loss (the sum of solution and sediments bicarbonate extractable Pi) for all soils. The order of loss (Pi, mg m−2) was soil dependent; greatest and lowest in the loam and loamy sand, respectively (loam: Pi[270] > IHP[128] > AS[108] > MC[97] > HA[49] > Control[33], and loamy sand: AS[42] > HA[23] > Pi[22] > IHP[18] > MC[13] > Control[4]), although order of runoff and soil loss were clay > loam > loamy sand. Treating with IHP and Pi at a similar total P level, led to comparable cumulative total‐P runoff losses, but runoff available Pi loss was much greater in the Pi treatment of soils with higher clay content (clay > loam > loamy sand). A derived isotherm relating sediment Olsen Pi to dissolved reactive Pi (DRP) concentration in runoff, was found useful for estimating runoff Pi losses from measured DRP, runoff volume and sediment concentration. The results could be explained by the impact of the amendments on soil structure stability, sealing, runoff and erosion levels associated with soil physical and chemical degradation. This article is protected by copyright. All rights reserved.

24774. 题目: Soil parent material controls organic matter stocks and retention patterns in subtropical China
文章编号: N20031506
期刊: Journal of Soils and Sediments
作者: Xiali Mao, Lukas Van Zwieten, Mingkui Zhang, Zhiteng Qiu, Yucai Yao, Hailong Wang
更新时间: 2020-03-15
摘要: Purpose The influence of parent material on soil organic carbon (SOC) retention remains largely unstudied. Here, we aimed to reveal the role of soil parent material on SOC stocks and elucidate the underlying SOC retention patterns for soils derived from limestone, quaternary red earth, granite, basalt, and tertiary red sandstone in subtropical China. Materials and methods The study assessed 110 topsoils (0–20 cm) under two land uses (forest and cultivated), but with similar topography. We compared soil properties (pH, oxides, multivalent cations, texture, aggregates) and SOC stocks, total SOC concentration as well as three organic C fractions (active, slow, and passive C). Factors influencing SOC concentration were explored using a combination of stepwise multiple regression analysis and redundancy analysis. Results and discussion Topsoil SOC stocks and SOC concentration varied significantly among the five parent materials, with the greatest values all observed in limestone-derived soils and the lowest in tertiary red sandstone–derived soils. While parent material significantly influenced both quantity and quality of SOC, there was no land use effect on the proportion of organic C fractions. Our results have also shown that parent material mediates land use impacts on SOC. The SOC stocks and SOC concentration in limestone, quaternary red earth, and basalt-derived soils were significantly higher in forest than in arable soils, while no significant land use effect was found for soils derived on granite and tertiary red sandstone. Soil aggregates, texture, content of Fe oxides, and multivalent cations accounted for 67.8% of the variation in SOC concentration, and both SOC stocks and SOC concentration were more closely related to aggregation and soil texture. The major influencing factors for SOC retention differed with parent material, with Ca2+/Mg2+-mediated interactions between organic matter and mineral surfaces being the main regulating processes for limestone-derived soils and oxide-mediated mechanisms to form stable aggregates being the likely SOC protecting patters for quaternary red earth and basalt-derived soils. Due to the coarse texture and low aggregate stability, the soils derived from granite and tertiary red sandstone lacked the properties for SOC preservation, with pH the main predictor for SOC concentration. Macroaggregates (> 2 mm) played especially important role in shaping SOC stocks. Conclusions Parent material exerts an influence on SOC stocks and retention patterns, and should be used in determining SOC storage potential for soils.

24775. 题目: Effects of long-term planting on PhytOC storage and its distribution in soil physical fractions in Moso bamboo forests in subtropical China
文章编号: N20031505
期刊: Journal of Soils and Sediments
作者: Chengpeng Huang, Yongchun Li, Lin Jin, Xiaoqiang Gong, Jiasen Wu, Da Dong, Scott X. Chang, Peikun Jiang
更新时间: 2020-03-15
摘要: Phytoliths are siliceous substances that are abundant within intercellular spaces and inside cells of numerous types of plants. During the formation of phytoliths, between 0.2 and 5.8% of organic carbon (C) can be occluded within the phytoliths. Phytolith-occluded C (PhytOC) in terrestrial ecosystems is a stable C sink and can be distributed in organic matter that is not strongly associated with soil minerals (LFOM) or that is strongly associated with mineral particles (forming organo-mineral complexes) (HFOM). We (1) investigated the impact of plantation age and soil depth on the size of the PhytOC pool and its distribution in soil physical fractions in Moso bamboo (Phyllostachys pubescens) forests; and (2) explore the relationship among phytoliths and PhytOC (and their fractions) concentrations and the soil properties.

24776. 题目: Effects of Fe-Mn-Ce oxide–modified biochar on As accumulation, morphology, and quality of rice (Oryza sativa L.)
文章编号: N20031504
期刊: Environmental Science and Pollution Research
作者: Fei Lian, Xuewei Liu, Minling Gao, Huizhong Li, Weiwen Qiu, Zhengguo Song
更新时间: 2020-03-15
摘要: The fluidity of arsenic (As) in soil used for rice cultivation under flooding conditions is the main reason for its high accumulation in rice, which poses a serious threat to human's health. Biochar can immobilize heavy metal (for example lead) of soil because of the strong binding of heavy metals to the inner biochar particles. We conducted a pot experiment to evaluate the effects of biochar (BC) and Fe-Mn-Ce oxide–modified biochar composites (FMCBCs) on the morphology, As accumulation, and grain quality of rice grown in As-contaminated soils. The biochar and FMCBC treatments significantly increased the dry weight of roots, stems, leaves, and rice grains grown in As-contaminated soil (P < 0.05). The As concentration in different parts of rice was significantly lower with treatment FMCBC3-2 (BC, Fe, Mn, and Ce weight ratio of 24:2:3:10) than with the BC and control (no BC) treatments. The application of FMCBC3-2 maximized the yield and quality of rice grains: rice grain yields were 61.45–68.41% higher over control and the proportion of essential amino acids in the rice grains was 31.01–44.62%. The application of FMCBCs also increased the concentration of Fe-Mn plaques, which prevent the uptake of As by rice, thereby mitigating the toxic effects of As-contaminated soil on rice. In summary, Fe-Mn-Ce oxide–modified BC composites fixed As, reducing its fluidity and the As concentration in rice. Our results show that FMCBC3 could play an important role in reducing As accumulation and increasing the grain yield and quality of rice, thus ensuring food safety in regions contaminated with As.

24777. 题目: Investigation of Primary and Secondary Particulate Brown Carbon in Two Chinese Cities of Xi’an and Hong Kong in Wintertime
文章编号: N20031503
期刊: Environmental Science & Technology
作者: Qian Zhang, Zhenxing Shen, Leiming Zhang, Yaling Zeng, Zhi Ning, Tian Zhang, Yali Lei, Qiyuan Wang, Guohui Li, Jian Sun, Dane Westerdahl, Hongmei Xu, Junji Cao
更新时间: 2020-03-15
摘要: Brown carbon (BrC), an aerosol carbonaceous matter component, impacts atmospheric radiation and global climate because of its absorption in the near-ultraviolet–visible region. Simultaneous air sampling was conducted in two megacities of Xi'an (northern) and Hong Kong (southern) in China in winter of 2016–2017. The aim of this study is to determine and characterize the BrC compounds in collected filter samples. Characteristic absorption peaks corresponding to aromatic C–C stretching bands, organo-nitrates, and C═O functional groups were seen in spectra of Xi'an samples, suggesting that the BrC was derived from freshly smoldering biomass and coal combustion as well as aqueous formation of anthropogenic secondary organic carbon. In Hong Kong, the light absorption of secondary BrC accounted for 76% of the total absorbances of BrC. The high abundance of strong C═O groups, biogenic volatile organic compounds (BVOCs) and atmospheric oxidants suggest secondary BrC was likely formed from photochemical oxidation of BVOCs in Hong Kong. Several representative BrC molecular markers were detected using Fourier transform ion cyclotron resonance mass spectrometry and their absorption properties were simulated by quantum chemistry. The results demonstrate that light absorption capacities of secondary anthropogenic BrC with nitro-functional groups were stronger than those of biogenic secondary BrC and anthropogenic primary BrC.

24778. 题目: Mapping soil organic carbon content using multi-source remote sensing variables in the Heihe River Basin in China
文章编号: N20031502
期刊: Ecological Indicators
作者: Tao Zhou, Yajun Geng, Jie Chen, Mengmeng Liu, Dagmar Haase, Angela Lausch
更新时间: 2020-03-15
摘要: Soil organic carbon (SOC) has a large impact on soil quality and global climate change. It is therefore important to be able to predict SOC accurately to promote sustainable soil management. Although the synthetic aperture radar (SAR) has many advantages and has been widely used in soil science research, it has rarely been used in previous SOC mapping studies based on remote sensing images. The purpose of this study was to investigate the ability of multi-temporal Sentinel-1A data in SOC prediction, by comparing the predictive performance of random forest (RF) and boosted regression tree (BRT) models in the Heihe River Basin in northwestern China. A set of 162 topsoil (0–20 cm) samples were taken and 15 environmental variables were obtained including land use, topography, climate, and remote sensing images (optical and SAR data). Using a cross-validation procedure to evaluate the performance of the models, three statistical indices were calculated. Overall, both RF and BRT models effectively predicted SOC content, exhibiting similar performance and producing similar spatial distribution patterns of SOC. The results showed that the addition of multi-temporal Sentinel-1A images improved prediction accuracy, with the root mean squared error (RMSE), the mean absolute error (MAE) and the coefficient of determination (R2) improving by 9.0%, 8.3% and 13.5%, respectively. Furthermore, the combination of all environmental variables had the best prediction performance explaining 75% of SOC variation. The most important environmental variables explaining SOC variation were precipitation, elevation, and temperature. The multi-temporal Sentinel-1A data in RF and BRT models explained 9% and 7%, respectively. The results from our case study highlight the usefulness of multi-temporal Sentinel-1 data in SOC mapping.

24779. 题目: Influence of human activity on the abundance, distribution and origin of fatty acids in sediments of two shallow lakes and implications for paleolimnological studies
文章编号: N20031501
期刊: Ecological Indicators
作者: Yongdong Zhang, Ting Peng, Yaling Su, Jinlei Yu, Yingxun Du, Zhengwen Liu
更新时间: 2020-03-15
摘要: During the past few decades, the majority of shallow lakes in the Yangtze River basin (Eastern China) have been impacted by heavy discharges of sewage and the intensification of aquaculture. These activities have significant potential to alter aquatic ecosystems and these changes may be reflected in the composition of lipid biomarkers in sediments at the time. In order to evaluate this effect, the abundances and distribution of fatty acids (FAs) were measured in 210Pb dated sediment cores from two anthropogenically impacted shallow lakes in the Yangtze River basin, Changdang and Taibai. Results from Lake Changdang revealed an extreme enrichment of zooplankton-derived C22:1 ω11 in sediments, with C22:1 ω11/n-C16 ratios reaching ~1.6 on average. This unusual distribution may have been caused by zooplankton blooms in the lake in the years before aquaculture was developed. Elevated abundances of C18:1 ω9 and short-chain n-alkanoic acids observed in pre-1977 sediments might be also derived from zooplankton. After 1977, FAs of zooplankton origin in Lake Changdang greatly declined in abundance, coincident with the introduction of planktivorous fish. Meanwhile, inputs of FAs from submerged/floating macrophytes, bacteria and algae increased as a result of eutrophication and reduced grazing pressure from zooplankton. In Lake Taibai, abundances of C22:1 ω11 were greatly reduced in all sediments and accounted for 38% of n-C16 on average, reflecting comparatively smaller inputs of zooplankton FAs owing to the earlier establishment of aquaculture in the lake. Relative enrichment of polyunsaturated FAs (PUFAs) and branched FAs (Br-FAs) in the sediments was attributed to high inputs of algal and bacterial organic matter (OM) in response to reduced predation and grazing by zooplankton. Rapid increases in PUFAs and Br-FAs in post-1970 sediments were driven by eutrophication in this period.

24780. 题目: Impacts of collapsing gullies on the dynamics of soil organic carbon in the red soil hilly region of southeast China
文章编号: N20031420
期刊: CATENA
作者: Yue Zhang, Dongfeng Zhao, Jinshi Lin, Lin Jiang, Bifei Huang, Fangshi Jiang, Ming-Kuang Wang, Hongli Ge, Yanhe Huang
更新时间: 2020-03-14
摘要: Collapsing gullies are one of the most serious soil erosion problems in the tropical and subtropical areas of South China. However, few studies have determined the effects of collapsing gullies on the redistribution and loss of soil organic carbon (SOC) in the red soil hilly region. This study investigated the variations in different kinds of SOC in a collapsing gully and a hillslope and the relationships between various soil properties and SOC. The results showed that the dissolved organic carbon (DOC), particulate organic carbon (POC), readily oxidizable organic carbon (ROOC) and total organic carbon (TOC) contents on the hillslope were higher than those in the collapsing gully. Below the location of upper catchment in the collapsing gully, the DOC, POC, ROOC and TOC contents were all greatly reduced, and there was no organic carbon enrichment in the alluvial fan and check dam. The stability of SOC in the collapsing gully was lower than that in the hillslope. The average free iron oxides (Fed), organically bound iron oxides (Fep) and clay contents in the collapsed soil were much lower than those on the hillslope. SOC content was significantly and positively correlated with the soil Fed, Fep and soil clay contents but negatively correlated with soil pH. Among these soil parameters, the dominant factors influencing TOC in the red soil hilly region were soil ROOC and soil pH. The SOC density of 0–30 cm soil in the collapsing gully was equivalent to nearly 15.9% of that in the hillslope. These results demonstrate that collapsing gullies have highly deteriorated soil properties and are therefore subject to accelerated SOC loss in the red soil hilly region.