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24481. 题目: Organic fertilizers have divergent effects on soil N 2 O emissions
文章编号: N19072311
期刊: Biology and Fertility of Soils
作者: Tiehu He, Junji Yuan, Jiafa Luo, Weijin Wang, Jianling Fan, Deyan Liu, Weixin Ding
更新时间: 2019-07-23
摘要: A field experiment was conducted in a subtropical tea (Camellia sinensis (L.) O. Kuntze) plantation in Jiangsu Province, China, including the following treatments: no nitrogen (N) fertilizer (control), conventional mineral N fertilizer (urea) (CN), soybean cake fertilizer (SF), pig manure (PM), cattle manure (CaM), chicken manure (CM), and CM + biochar (CMB). Cumulative nitrous oxide (N₂O) and nitric oxide (NO) emissions were 4.8 ± 0.1 and 3.7 ± 0.3 kg N ha⁻¹ year⁻¹ under CN, respectively, and increased to 5.4 ± 0.2 and 4.6 ± 0.3 kg N ha⁻¹ year⁻¹ under SF (P < 0.05), respectively. Treatments with livestock manures (PM, CaM, and CM) reduced N₂O (41.4–49.6%) and NO (46.5–59.8%) emission in comparison to CN. Combined amendment of CM and biochar more effectively reduced N₂O emissions than CM treatment alone. Based on a meta-analysis of 26 global paired measurements in acid soils, the threshold of C/N ratios of organic fertilizers between the positive and negative responses of N₂O emissions to organic fertilizers was 8.6 with a range of 4.5–22.3 (95% confidence interval), indicating that reduced N₂O emission under PM, CaM and CM was potentially due to their C/N ratios compared to the threshold. Organic fertilizer application did not influence tea yield, while combined application of CM and biochar increased tea yield and resulted in the least yield-scaled N₂O emission. N₂O and NO emission factors for N fertilizers applied under CN were 1.9 ± 0.1% and 1.5 ± 0.2%, respectively, and reduced to 0.08 ± 0.04% and 0.12 ± 0.04% under CMB, respectively. The results suggest that tea plantations in the subtropical region are hotspots for N₂O and NO emissions. Combined application of chicken manure and biochar could mitigate N gas emissions and increase yield in the tea plantation systems.

24482. 题目: Effects of residual ozone on the performance of microorganisms treating petrochemical wastewater
文章编号: N19072310
期刊: Environmental Science and Pollution Research
作者: Liya Fu, Changyong Wu, Yuexi Zhou, Jiane Zuo, Guangqing Song
更新时间: 2019-07-23
摘要: This study investigated the effects of residual ozone on the performance of microorganisms treating petrochemical wastewater using batch experiments with low and high ozone dosages (5.0 mg/L and 50.0 mg/L, respectively). The results indicated that the low residual ozone concentration significantly increased COD removal by 24.21% in the biological process compared to control group with no ozone residual, while the high residual ozone concentration showed the opposite effect. In the reactor with low residual ozone concentration (0.45 mg/L), the amount of loosely bound (LB)-extracellular polymeric substances (EPS) in the activated sludge decreased by 23.23%, while the amount of tightly bound (TB)-EPS increased by 129.16% compared to the none-ozone residual reactor. In addition, the low residual ozone was found to improve the bioactivity of activated sludge by 139.73% in the first 30 min of the biological process. In the reactor with high residual ozone concentration (0.91 mg/L), both LB- and TB-EPS of the activated sludge increased, while bioactivity decreased. This implies that low residual ozone in a bio-reactor can enhance microbial activity by increasing contact between the pollutants and cells by removing LB-EPS covering the outer layer of the sludge. The microorganisms in the sludge samples could be classified into three groups representing those that are susceptible to ozone, tolerant to low dose of residual ozone, and resistant to high dose of residual ozone. The resistant bacteria Gemmatimonadaceae uncultured became predominant, with a relative abundance of 11.37%, under low residual ozone conditions, while it decreased at high ozone concentrations. The results showed that a certain amount of residual ozone could stimulate the activity of microorganisms by altering the EPS fraction and structure of the microbial community, and thus it is important for the removal of refractory organics from wastewater in the ozone-biological process.

24483. 题目: In situ immobilization of Cr and its availability to maize plants in tannery waste–contaminated soil: effects of biochar feedstock and pyrolysis temperature
文章编号: N19072309
期刊: Journal of Soils and Sediments
作者: Muhammad Imran Rafique, Adel R. A. Usman, Munir Ahmad, Abdelazeem Sallam, Mohammad I. Al-Wabel
更新时间: 2019-07-23
摘要: Purpose: Tannery waste–contaminated soil has a high amount of several toxic chemicals and heavy metals including chromium (Cr), which makes it unsuitable for agriculture practices. Majority of studies have reported the use of biochar (BC) as an amendment to restore contaminated soil. The efficiency of BC to immobilize Cr depends on its pretreatment and feedstock. This study aimed to investigate the potential of using BC for Cr immobilization and reducing its availability to maize plants in tannery waste–contaminated soil. The effect of BC on plant growth and heavy metal (Cr, Cu, Zn, Pb, Fe, and Mn) contents of maize shoots was also investigated. Materials and methods: The soil was collected from landfill areas of Riyadh city (N 24° 25′, E 46° 34′). BCs were produced by pyrolyzing jujube (Ziziphus spina-christi) leaves (JL) and manure (M) waste at 300 and 700 °C. Collected soil and produced materials were characterized physically and chemically by following standard procedure. A greenhouse pot experiment was conducted with unamended tannery waste–contaminated soil and soil amended with the obtained BCs (JLBC-300, JLBC-700, MBC-300, and MBC-700) at an application rate of 50 g kg⁻¹ and cultivated with maize (Zea mays L.). Before cultivation, soil-soluble Cr was measured in five leachate cycles. Dry matter and heavy metal (Cr, Cu, Zn, Pb, Fe, and Mn) contents of maize shoots were measured after harvesting. Results and discussion: The results show that BCs produced at 700 °C showed the highest decrease in the concentrations of soil-soluble Cr and reduced its cumulative concentrations in soil leachates by about 93% and 59.0% for MBC-700 and JLBC-700 compared with the control soil, respectively. Overall, the highest decrease in cumulative soluble Cr was pronounced for MBC-700 followed by JLBC-700. For heavy metal contents in shoots, Cr concentrations were under detection limit in all treatments. However, BC amendments showed significant differences from the control for Cu, Mn, and Fe. Conclusions: From findings, it could be concluded that application of BCs pyrolyzed at 700 °C (especially for MBC-700) could be used as an amendment for reducing Cr mobility in tannery waste–contaminated soil and may create favorable conditions for crop production.

24484. 题目: Leaf wax n-alkane pattern and compound-specific δ13C of plants and topsoils from semi-arid Mongolia
文章编号: N19072308
期刊: Biogeosciences
作者: Julian Struck, Marcel Bliedtner, Paul Strobel, Jens Schumacher, Enkhtuya Bazarradnaa, and Roland Zech
更新时间: 2019-07-23
摘要: n-Alkane pattern and their compound-specific δ¹³C signatures are valuable proxies for paleoenvironmental reconstructions. So far, their potential has not been investigated in semi-arid to arid regions. We have therefore analysed the leaf wax n-alkanes and their compound-specific δ¹³C of five plant species (Poaceae, Cyperaceae, Artemisia spp., Caragana spp. and Larix sp.), and topsoils (0–5 cm) along two transects in central and southern Mongolia. Grasses depict a distinct dominance of the n-C₃₁ homologue, whereas Caragana spp. and Artemisia spp. are dominated by n-C₂₉. Larix sp. is characterized by the mid-chain n-alkanes n-C₂₃ and n-C₂₅. From plant to soil, n-alkane homologue pattern show the potential to differentiate between grass covered sites from those covered by Caragana spp. n-Alkane concentrations and OEP values of the topsoils are distinctly influenced by mean annual temperature, mean annual precipitation and aridity, likely reflecting the degree of n-alkane degradation and biomass production. In contrast, the n-alkane average chain-length and the n-alkane ratio (n-C₃₁ / n-C₂₉ + n-C₃₁) are not affected by climatic parameters. The compound-specific δ¹³C signatures are strongly corelated to climate, showing a significant enrichment with increasing aridity, indicating the effect of water use efficiency. Our calibration results suggest that long-chain n-alkanes and their compound-specific δ¹³C signatures have great potential to reconstruct paleoenvironmental and -climatic conditions when used in sediment archives from Mongolia.

24485. 题目: Understanding the granulation of partial denitrification sludge for nitrite production
文章编号: N19072307
期刊: Chemosphere
作者: Shenbin Cao, Rui Du, Hanyu Zhang, Yongzhen Peng
更新时间: 2019-07-23
摘要: Partial-denitrification (PD) has previously been demonstrated to be another pathway for nitrite production, which provides a cost-effective approach for nitrate (NO₃⁻-N) removal through combing with anammox. In this study, the formation of PD granules was firstly investigated in a sequencing batch reactor (SBR) with influent nitrate of 60 mg N/L. The granulation process was explored via the physicochemical and biological characterization. Sludge granulation initiated within the first 20 days with an average size of 93.7 μm in diameter, it experienced a developing, shaping and matured periods, with a maximum size of 709.3 μm obtained. High nitrite production of PD was always maintained during the granulation with a mean nitrate-to-nitrite transformation ratio (NTR) of 88.3%, and in-situ maximum NO3–N reduction rate of 84.9 mg N/h/g VSS was obtained. Mature PD granules hold an excellent settling property with 5-min sludge volume index (SVI₅) of 32.0 mL/g MLSS obtained and smooth surface with large amounts of rod bacteria covered. CaCO₃ precipitates formed in the PD process played a vital role in the initial granulation, acting as the nucleus for cell attachment. Extracellular polymeric substances (EPS), mainly the proteins (PN) content, was found to be of supreme importance in granules developing and maintaining its structural stability. Besides, the abundance of Flavobacterium and norank_p__Gracilibacteria were revealed to be in accordance with the change of granules size, seemed to contribute to sludge granulation. The developed granule-based PD integrated with anammox process provides an engineering-feasible and economic-favorable solution for industrial nitrate wastewater treatment.
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24486. 题目: Water-soluble mercury induced by organic amendments affected microbial community assemblage in mercury-polluted paddy soil
文章编号: N19072306
期刊: Chemosphere
作者: Hualing Hu, Meng Li, Guoxi Wang, Marios Drosos, Zhen Li, Zhengyi Hu, Beidou Xi
更新时间: 2019-07-23
摘要: Mercury (Hg) pollution or organic amendments (OA) may individually induce changes in the microbial community of paddy soils. However, little is known regarding the interaction of Hg and OA and the effect of different OA applications on the microbial community assemblage in Hg-polluted paddy soil. A soil incubation experiment was performed by applying three organic amendments (OA), namely a food-waste compost (FC), and its HA and FA, into an Hg-polluted paddy soil to examine the changes in the microbial community and merA/merB gene abundance. The results showed that the OA treatments promoted total (SOC) and dissolved organic carbon (DOC) in soils, which may harbor copiotrophic bacteria. The HA and FA treatments decreased microbial diversity and richness along with an increase of water-soluble Hg (WHg) through the complexation of DOC to Hg, which may be mainly attributed to the enhanced Hg biotoxicity to soil microbiome induced by the increased WHg under these two treatments. Additionally, the WHg enhancement also contributed to the increase of Hg-resistant bacteria and merA/merB gene abundance, and consequently, induced changes in the microbial community. These results indicated the interaction of Hg and different OA induced the variation of WHg fraction in paddy soil, which played a fundamental role in the distinct responses of the microbial community assemblage. Collectively, the application of FA and HA to Hg-polluted soil should be limited considering Hg risk to microbiome, and FC can be an alternative.
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24487. 题目: Investigation on the effects of sediment resuspension on the binding of colloidal organic matter to copper using fluorescence techniques
文章编号: N19072305
期刊: Chemosphere
作者: Tianli Bao, Peifang Wang, Bin Hu, Yue Shi
更新时间: 2019-07-23
摘要: Colloidal organic matter (COM), an important component of dissolved organic matter (DOM), plays a significant role in the transport and cycling process of the heavy metals. In this study, COM was fractionated from DOM using 0.2 μm, 100 kDa, and 2 kDa ultrafiltration membranes and the fluorescence spectra of the COM fractions were obtained. Excitation and emission matrix–parallel factor analysis and two-dimensional fluorescence correlation spectroscopy were applied to investigate the effect of sediment resuspension on the heavy metal binding characteristics of COM fractions with different molecular weights. Compared with the DOM fractions, COM exhibited stronger binding affinities and more binding sites for Cu(II), which was attributed to the significant binding effects of the components of COM. Our results suggested that the protein-like components were mainly responsible for binding heavy metals in the high-molecular-weight fraction (>100 kDa), whereas the humic-like components were responsible in the low-molecular-weight fraction (<100 kDa). Furthermore, sediment resuspension significantly influenced the composition and heavy metal binding characteristics of COM. Following resuspension, the binding affinity of COM decreased significantly, which might be attributed to the binding competition from inorganic colloids. Thus, COM plays an important role in the binding and transportation behavior of heavy metals, which is an important consideration in shallow lake ecosystems.

24488. 题目: Origin, distributions, and environmental significance of ubiquitous humic-like fluorophores in Antarctic lakes and streams
文章编号: N19072304
期刊: Water Research
作者: Morimaru Kida, Taichi Kojima, Yukiko Tanabe, Kentaro Hayashi, Sakae Kudoh, Nagamitsu Maie, Nobuhide Fujitake
更新时间: 2019-07-23
摘要: This study characterized dissolved organic matter (DOM) obtained from 47 lakes and 2 streams on ice-free areas at Lützow-Holm Bay and Amundsen Bay in East Antarctica (n = 74), where few biogeochemical studies have been historically conducted. Samples were analyzed for basic water chemistry and by resin fractionation, UV–vis spectroscopy, and excitation emission matrix spectroscopy combined with parallel factor analysis (EEM-PARAFAC). Salinity of the samples ranged very broadly from fresh to hypersaline as a result of evaporative concentration. There was a clear positive correlation between log-salinity and the spectral slopes of DOM (S_275–295), an indicator of photodegradation. Thus, we interpreted the correlation as a progression of photodegradation by prolonged water retention time. Of the identified seven PARAFAC components, three ubiquitous humic-like components decreased as photodegradation progressed, while a photorefractory UVC humic-like component increased its relative abundance. A non-humic component, traditionally defined as Peak N, did not show a trend depending on photodegradation, and its level was high in nutrient-rich lakes, presumably due to high in-situ production. We found robust correlations between the relative abundance of the ubiquitous humic-like components and that of the Peak N component in the bulk DOM irrespective of water types or ice-free areas. We proposed there were common processes that generated the ubiquitous humic-like components from the Peak N component in the Lützow-Holm Bay and Amundsen Bay lakes and streams, such as bacterial processing of primary production-derived DOM and photochemical transformation of microbial DOM.

24489. 题目: Kinetic modeling of lag times during photo-induced inactivation of E. coli in sunlit surface waters: Unraveling the pathways of exogenous action
文章编号: N19072303
期刊: Water Research
作者: Efraim A. Serna-Galvis, Jean Arnaud Troyon, Stefanos Giannakis, Ricardo A. Torres-Palma, Luca Carena, Davide Vione, Cesar Pulgarin
更新时间: 2019-07-23
摘要: The present work presents a kinetic analysis of the exogenous photo-induced disinfection of E. coli in natural waters. Herein, the inactivation of bacteria by light and photo-generated transient species, i.e., hydroxyl radical (HO^•), excited triplet states of organic matter (³CDOM*) and singlet oxygen (¹O₂), was studied. It was found that the exogenous disinfection of E. coli proceeds through a lag time, followed by an exponential phase triggered by photo-generated HO^•, ¹O₂ and ³CDOM*. Also, we report that the concentration increased of transient species (and especially HO^•) precursors decreased the lag times of bacteria inactivation. Due to the limitations of the competition kinetics methodology to include the lag phase, an alternative strategy to study the interaction between E. coli and photo-generated transient species was proposed, considering the log-linear pseudo-first order rate constants and lag-times. On this basis and by using APEX software, a full kinetic analysis of exogenous bacterial inactivation, taking into account both lag-time and exponential decay, was developed. This approach provided insights into the conditions that could make exogenous inactivation competitive with the endogenous process for the E. coli inactivation in natural sunlit waters. Hence, this research contributes to the understanding of fundamental kinetic aspects of photoinduced bacterial inactivation, which is the basis for light-assisted processes such as the solar disinfection (SODIS).
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24490. 题目: Disposal of Fenton sludge with anaerobic digestion and the roles of humic acids involved in Fenton sludge
文章编号: N19072302
期刊: Water Research
作者: Mingwei Wang, Zhiqiang Zhao, Yaobin Zhang
更新时间: 2019-07-23
摘要: Fenton sludge (FS) generated from Fenton process with high contents of iron and organic contaminants is regarded as a hazardous waste that requires to be properly disposed. Considering that Fe(III) compounds could stimulate dissimilatory iron reduction (DIR) and enrich iron reducing bacteria (IRB) that utilized Fe(III) as electron acceptor to oxidize organic matters, FS was introduced in anaerobic digestion (AD) reactors for treating wastewater meanwhile disposing FS. Results showed that methane production and organic matters removal significantly increased with dosing FS from 0 to 2.4 g. Also, a majority of organic matters involved in FS was mineralized, including 38.5% of PAHs removal. Humic acids (HA) with redox-activity involved in FS might affect efficiency of DIR. After extracting HA from FS, the rate and the extent of Fe(III) reduction of FS decreased by 33.2% and 13.9%, respectively. Together with analysis of the electron exchange capacity of HA, it suggested that the HA involved in FS might serve as an electron shuttle to effectively promote DIR. The increase of sludge conductivity and the enrichment of IRBs in microbial communities with dosage of FS were in agreement with the above results.
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24491. 题目: Effects of molecular weight fractions and chemical properties of time-series cyanobacterial extracellular polymeric substances on the aggregation of lake colloidal particles
文章编号: N19072301
期刊: Science of The Total Environment
作者: Wei Si, Huacheng Xu, Ming Kong, Jin Liu, Mengwen Xu, Xin Liu
更新时间: 2019-07-23
摘要: Colloidal particles in lake waters interact inevitably with cyanobacterial extracellular polymeric substance (EPS), which will change their behavior and fate. Quantitative prediction of the effects of cyanobacterial EPS on colloidal behavior is difficult due to its variability and heterogeneity. To explore the effects of molecular weight (MW) fractions and chemical properties of cyanobacterial EPS on aggregation kinetics of colloidal particles, time-series cyanobacterial samples were collected in Lake Taihu, China, from April to November (during blooming and maintenance period), with the bulk EPS matrix fractionating into low MW (LMW–, <1 nm) and high MW (HMW–, 1 nm–0.45 μm) fractions. HMW–EPS was generally characterized with higher absorbance and predominant distribution of protein-like substances, while LMW–EPS contained mainly the humic- and fulvic-like substances. The absorbance, molecular size, and humification degree for each MW fraction consistently increased from April to November, showing obvious temporal variations from blooming period to maintenance period. As for the MW-dependent aggregation behaviors, the HMW–EPS provided better stability against aggregation than the LMW–EPS, and the bulk EPS matrix that consisted of HMW– and LMW–fractions exhibited the effects intermediate between that of each fraction alone. Regardless of MW fractions, the effects of EPS-induced stability enhancement were more evident in maintenance period than in blooming period. Further analysis showed that the colloidal stability was correlated positively with SUVA₂₅₄ (R² = 0.82–0.93) but negatively with Slope_275–295 (R² = 0.53–0.91) of UV–Vis absorption spectra, indicating that aromaticity and MWs were two critical parameters controlling colloidal aggregation. Therefore, cyanobacterial EPS can exhibit variable effects on colloidal stability, and characterization of MW distribution is strongly required in predicating the behavior and fate of colloidal particles in water environments.
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24492. 题目: Enhanced activity of soil nutrient‐releasing enzymes after plant invasion: a meta‐analysis
文章编号: N19072204
期刊: Ecology
作者: Yong Zhou, A. Carla Staver
更新时间: 2019-07-22
摘要: Plant invasion can significantly alter soil nutrient cycling of ecosystems. How these changes are linked to soil enzyme activities is still unknown, however, even though these are proximate agents of organic matter decomposition and nutrient release. We performed a meta‐analysis of 60 case studies examining responses of 10 unique soil enzymes to plant invasion, and tested whether invaded soils differed in their enzyme activities from uninvaded soils. We also examined whether increases in soil nutrient‐releasing enzyme activity were paralleled by enhanced soil nutrient availability after plant invasion. Overall, we found that plant invasion had significant impacts on the activities of 7 types of soil enzymes. Plant invasion had inconsistent impacts on C decomposing enzymes, but invaded sites had significantly higher activities of soil enzymes related to N‐ and P‐release than non‐invaded sites. Increases in nutrient‐releasing enzyme activity after plant invasion ranged from +23% to +69%, which potentially results in a linear increase of soil nutrient availability in response to enhanced enzyme activities. Invaded soils also had higher nutrient stocks and soil microbial biomass than uninvaded soils. Our results suggest that enhanced activity of soil nutrient‐releasing enzymes after plant invasion may accelerate nutrient cycling, potentially creating a nutrient‐rich soil environment that benefits invaders and promotes their persistence as invasive plants often appear to be more resource‐demanding and competitive than native species. This article is protected by copyright. All rights reserved.

24493. 题目: Cadmium in soils and groundwater: A review
文章编号: N19072203
期刊: Applied Geochemistry
作者: Andreas Kubier, Richard T. Wilkin, Thomas Pichler
更新时间: 2019-07-22
摘要: Cadmium (Cd) is a non-essential trace element that is widely distributed in the environment. Both geogenic and anthropogenic sources can elevate Cd concentrations in soils and groundwater, which are important for maintaining healthy supplies of food and safe drinking water. Elevated Cd doses are carcinogenic to humans. The WHO Guidelines for Drinking-Water Quality recommend a guideline value for Cd of 3 μg/L. Important anthropogenic Cd sources include mining, atmospheric deposition of combustion emissions, and the use of Cd-containing fertilizers. We document several cases of Cd pollution in soil and groundwater based on worldwide accounts. Besides anthropogenic Cd sources, Cd is also incorporated into sulfides, carbonates, and phosphorites resulting in elevated Cd concentrations in associated rock types. The crustal median Cd content is 0.2 mg/kg. In soils, Cd occurs at concentrations of 0.01–1 mg/kg with a worldwide mean of 0.36 mg/kg. Weathering can lead to Cd concentrations up to 5 μg/L in soil water and up to 1 μg/L in groundwater. In aqueous solutions, Cd generally occurs as the divalent Cd²⁺ and it is mobilized mainly in oxic, acidic conditions. Cadmium sorption is enhanced by the presence of high amounts of hydrous oxides, clay minerals, and organic matter, and its mobility is further influenced by pH, the redox state, and ionic strength of the solution. However, Cd can remain in solution as water-soluble complexes with anions, such as CdCl⁺ and Cd(SO₄)₂^2-, and dissolved organic matter while sorption and precipitation decrease the aqueous concentration of most other heavy metals. As a consequence, Cd is one of the most mobile heavy metals in the environment. The elevated mobilization potential, e.g., through competition and ligand induced desorption, is the reason for faster Cd release from soil into groundwater than other heavy metals. The goal of this study was to present a broad overview of the origin and concentration of Cd in groundwater, and its reaction pathways in aquatic environments. To gain an overview of the hydrochemical behavior of Cd, cases of Cd pollution in soil and groundwater, studies investigating Cd release, and information about the legal framework were compiled.

24494. 题目: Insight into the vertical characteristics of dissolved organic matter in 5-m soil profiles under different land-use types on the Loess Plateau
文章编号: N19072202
期刊: Science of The Total Environment
作者: Wen Li, Xiaoxu Jia, Ming Li, Haiming Wu
更新时间: 2019-07-22
摘要: Dissolved organic matter (DOM) is a natural chemical component of all soils and influences soil organic pollutant migration, nutrient cycling, and global climate change. Previous field studies have focused on a single ecosystem, such as cropland, grassland, or forestland. However, the potential effect of different land-use types on the vertical distribution of soil DOM quantity and quality remains unclear. This study investigated the vertical characteristics of DOM in 5-m soil profiles under different land-use types (cropland, grassland, and forestland) on the Loess Plateau. The data from ultraviolet-visible spectral and parallel factor analysis of fluorescence excitation-emission matrix spectrophotometry were combined. These results indicated that the mean content of dissolved organic carbon (DOC) in the 30-yr forestland (203.33 mg kg⁻¹ soil) was the highest, and the lowest was observed in the cropland (83.70 mg kg⁻¹ soil). Meanwhile, the mean DOC content of the forestland increased through time, particularly after 20 years. In other words, afforestation activities only significantly affected soil DOM after a long time (over 20 years). The DOC content of the cropland initially increased and then decreased with soil depth in the 1-m soil profiles, which may be related to agricultural activities. Three fluorescence components, including two humic acid-like substances (C1 and C3) and a tryptophan-like substance (C2), were identified from all samples. The humic acid-like components significantly decreased by 51% with soil depth, while the tryptophan-like component increased by 49%, particularly in the cropland. The variation in ultraviolet-visible spectral and optical indexes also indicated that soil DOM was dominated by both microbial and terrestrial sources. These findings help to understand the dynamics of DOC in deep soil profiles and the biogeochemical effects of DOM in the natural environment.
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24495. 题目: Fungi and bacteria respond differently to changing environmental conditions within a soil profile
文章编号: N19072201
期刊: Soil Biology and Biochemistry
作者: Sebastian Preusser, Christian Poll, Sven Marhan, Gerrit Angst, Carsten W. Mueller, Jörg Bachmann, Ellen Kandeler
更新时间: 2019-07-22
摘要: Contrasting environmental conditions in topsoil and subsoil determine both abundance and function of soil microbial communities, affecting carbon (C) dynamics throughout the entire soil profile. Although the response of soil microorganisms to single factors such as substrate availability or micro-climatic conditions has been frequently studied, fewer studies have focused on complex interactions between substrate availability and environmental conditions. To address this, we employed vertical soil translocations between topsoil and subsoil horizons of an acid and sandy Dystric Cambisol under European beech forest in Lower Saxony, Germany, to investigate the impact of changing habitat conditions on microbial decomposer communities. To follow microbial substrate utilization at different soil depths, we created hot spots of fresh organic matter (OM) by adding ¹³C-labelled root litter. Soil samples were taken every three months over an experimental period of twelve months (June 2014 to June 2015).Generally, microbial biomass was strongly controlled by C availability throughout the profile. The importance of root litter as a microbial C source increased from topsoil to subsoil, but changes in available C sources affected fungi and bacteria differently. Fungi preferentially used root litter-derived C throughout the entire soil profile, demonstrating that limited access to preferred substrates, rather than micro-climatic conditions, was the main driver of decreasing fungal abundance with soil depth. In contrast, bacteria intensified utilization of root-derived C only in the absence of alternative C sources in the subsoil and were more strongly affected by spatial separation from C sources. Low soil moisture in combination with the highly sandy subsoil environment limited bacterial access to their substrates and, consequently, bacterial growth. In conclusion, fungal C utilization relies mainly on the quantity of recent plant-derived substrates, whereas bacterial access to substrates is additionally controlled by environmental conditions. This study indicates that limited microbial access to their heterogeneously distributed substrates may be an important factor for C accumulation and stabilization in subsoils.

24496. 题目: Can biochar application improve nitrogen removal in constructed wetlands for treating anaerobically-digested swine wastewater?
文章编号: N19072109
期刊: Chemical Engineering Journal
作者: Likui Feng, Ruigang Wang, Lixia Jia, Haiming Wu
更新时间: 2019-07-21
摘要: In this study, aerated constructed wetlands (CWs) modified with biochar were used to treat anaerobically-digested swine wastewater. Nitrogen removal performance and mechanisms were comparatively investigated by exploring the dynamic transformation of dissolved organic matter (DOM) in water. It was demonstrated that removal efficiencies of chemical oxygen demand (COD) and ammonium nitrogen (NH₄⁺-N) were 63.06–77.18% and 87.19–96.54% in aerated CWs with and without biochar application under various influent strengths. However, total nitrogen (TN) removal could not be enhanced in aerated CWs with biochar application (30.92–40.12%) compared that in conventional aerated CWs (40.83–48.70%), which might be related to insufficient carbon sources and lower pH values in systems. More average N₂O emission fluxes (185.43–443.33 μg m⁻² h⁻¹) were detected in aerated CWs with biochar application at higher influent strengths. Humic-like substances were identified as major components of DOM in water by using fluorescence excitation-emission-matrix combined with parallel factor analysis (EEM-PARAFAC), which could result in insufficient carbon source for denitrification due to the refractory characteristics. The results suggested that the high-temperature biochar may be inappropriate to effectively increase anaerobically-digested swine wastewater treatment performance in CWs under intermittent aeration operations.
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24497. 题目: Recovery of high-value and scarce resources from biological wastewater treatment: Sulfated polysaccharides
文章编号: N19072108
期刊: Water Research
作者: Weiqi Xue, Qian Zeng, Sen Lin, Feixiang Zan, Tianwei Hao, Yuemei Lin, Mark C.M. van Loosdrecht, Guanghao Chen
更新时间: 2019-07-21
摘要: Recovering materials with high value and increasing market demand from sewage and/or sludge is becoming more attractive than recovering traditional resources such as nutrients and biogas. Sulfated polysaccharides (SPs) are valuable and scarce raw materials that can only be produced from marine algae and a few types of animal tissues. This study evaluated if SPs are present in activated sludge obtained from saline sewage with a high level of sulfates present. The presence of SPs-containing extracellular polymeric substances (EPS) was confirmed and quantified for both sludge from lab-scale reactors and full-scale plants for the first time. SPs in the sludge of a lab-scale reactor operated under alternating aerobic/anoxic conditions with 500 mg/L sulfate in the influent (which is typical of Hong Kong saline sewage) reached 342.8 ± 0.3% mg/gVSS, and sludge taken from a full-scale saline wastewater treatment plant (WWTP) contained 418.1 ± 0.4% mg/gVSS of SPs. Purity of the extracted SPs was comparable to that of commercial industrial-grade products. Key bioactivities of SPs (i.e. fucoidan, carrageenan and heparin), namely anti-angiogenesis, anticoagulant and antioxidant, were confirmed after extraction and purification. Interestingly, operating conditions had a strong influence on the contents and types of SPs synthesized in sludge as well as its bioactivities. Although the detailed synthetic pathways of SPs in activated sludge remain unclear, the current study has made a first attempt to recover a high–value scarce resource from biological wastewater treatment.
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24498. 题目: TAK1 knock-down in macrophage alleviate lung inflammation induced by black carbon and aged black carbon
文章编号: N19072107
期刊: Environmental Pollution
作者: Zhiyuan Cheng, Hongqian Chu, Siqi Wang, Yao Huang, Xiaohong Hou, Qi Zhang, Wenjuan Zhou, Lixia Jia, Qinghe Meng, Lanqin Shang, Yiming Song, Weidong Hao, Xuetao Wei
更新时间: 2019-07-21
摘要: Black carbon (BC) can combine with organic matter and form secondary pollutants known as aged BC. BC and aged BC can cause respiratory system inflammation and induce lesions at relevant sites, but the underlying mechanism has remained unknown. To gain insight into the potential mechanisms, we focused on macrophages and transforming growth factor β-activated kinase 1 (TAK1) which are a crucial factor in inflammation. Our research aims to determine the role of TAK1 in macrophages in pulmonary inflammation induced by particulate matter. In this study, BC and 1,4-naphthoquinone were mixed to model aged BC (1,4NQ-BC) in atmosphere. BC induced mice lung inflammation model, lung macrophage knock-down TAK1 animal model and primary macrophage knock-down TAK1 model were used to explore whether TAK1 in macrophage is a critical role in the process of inflammation. The results showed that the expressions of inflammatory cytokines (IL-1β, IL-6, IL-33) mRNA were significantly increased and the phosphorylation of MAPK and NF-κB signaling pathway related proteins were enhanced in RAW 264.7 cell lines. In vivo studies revealed that the indicators of pulmonary inflammation (pathology, inflammatory cell numbers) and related cytokines (IL-1β, IL-6, IL-33) mRNA expressions in CD11c-Map3k7^−/− animals were significantly lower than wild-type animals after mice were instilled particles. In mice primary macrophages, the expressions of IL-6, IL-33 mRNA were inhibited after TAK1 gene was knock-down. These results unequivocally demonstrated that TAK1 plays a crucial role in BC induced lung inflammation in mice, and we can infer that BC and 1,4NQ-BC cause these inflammatory responses by stimulating pulmonary macrophages.

24499. 题目: Aluminum distribution heterogeneity and relationship with nitrogen, phosphorus and humic acid content in the eutrophic lake sediment
文章编号: N19072106
期刊: Environmental Pollution
作者: Qingwei Lin, Xue Peng, Biyun Liu, Fenli Min, Yi Zhang, Qiaohong Zhou, Jianmin Ma, Zhenbin Wu
更新时间: 2019-07-21
摘要: Increasing amount of aluminum (Al) gets into aquatic ecosystem through anthropogenic activity, but the knowledge about Al migration and relationships with sediments possessing different physico-chemical properties in eutrophic lakes is limited. Here, the Al migration rule and relationships with sediment nutritions in the Hangzhou West Lake, China was investigated, where a certain amount of residual Al-salts can enter because of the pre-treatment of the Qiantang River diversion project every day. Results revealed the obvious spatial distribution heterogeneity of Al in sediment vertical direction and horizontal direction following water flow. The Al content in sediment ranged 0.463–1.154 g kg⁻¹ in Maojiabu Lake, and ranged 9.862–40.442 g kg⁻¹ in Xiaonanhu Lake. Higher Al content distributed in upper layer sediment in lake with more disturbance. Total nitrogen (TN) contents were higher 0.917–3.387 mg g⁻¹ and 0.627–0.786 mg g⁻¹ in upper layer sediment than that in lower layer in Maojiabu Lake and Xiaonanhu Lake, respectively. Total phosphorus (TP) content ranged 0.779–2.580 mg g⁻¹, in which IP and Fe/Al-P contributed 24.9–80.8% and 17.0–51.6%, respectively. Correlations between Al content with nutrition, humic acid (HA) etc. of sediment regionally varied in Maojiabu and Xiaonanhu Lake. Spatial distribution of Al-salt in eutrophic lakes closely related with the physico-chemical characteristics of nutrients, humus, human disturbance and water division parameters. Results provides new insight into Al-salts migration and references for Al-risk evaluating in eutrophic lakes.
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24500. 题目: Assessing C–N balance and soil rejuvenation capacity of vermicompost application in a degraded landscape: A study in an alluvial river basin with Cajanus cajan
文章编号: N19072105
期刊: Environmental Research
作者: Subhasish Das, Rangbamon Teron, Buddhadeb Duary, Satya Sundar Bhattacharya, Ki-Hyun Kim
更新时间: 2019-07-21
摘要: Organic-dependent agriculture has gradually become appreciated worldwide despite scarce data on its ability to rejuvenate land quality. In this work, a popular cultivar of Cajanus cajan was grown in a nutrient-fatigued area with vermicompost (VC) and farmyard manure (FYM)partially replacing chemical fertilization (CF) (reduced by 10 and 50%) for four years. C–N mineralization kinetic equations were applied for the first time to assess the efficacy of vermicompost-based nutrient schemes on C–N balance in arable soil. The equations suggested that 10 and 50% replacement of chemical fertilization with vermicompost significantly improves C and N mineralization in the cultivated soil. In addition, humified C (humic acid and fulvic acid) content achieved 4-and 10-fold gains under CF₅₀/VC₅₀ and CF₉₀/VC₁₀ treatments respectively. In the CF₅₀/VC₅₀ treatment, there was apparent improvement in soil organic C storage (SOC_str) (42.6–57.4%), water holding capacity, and microbial health along with reduction in bulk density (6.10–13.0%). Moreover, soil quality improvement in terms of crop production with the application of CF₅₀/VC₅₀ was strongly evident. Overall, this study validates that vermicompost can be used successfully to achieve sustainable agricultural growth by effectively arresting land degradation.
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