18641. 题目: Comparative efficiency of peanut shell and peanut shell biochar for removal of arsenic from water
期刊: Environmental Science and Pollution Research
作者: Muhammad Sohail Sattar, Muhammad Bilal Shakoor, Shafaqat Ali, Muhammad Rizwan, Nabeel Khan Niazi, Asim Jilani
摘要: Contamination of surface water and groundwater streams with carcinogenic chemicals such as arsenic (As) has been a major environmental issue worldwide, and requires significant attention to develop new and low-cost sorbents to treat As-polluted water. In the current study, arsenite (As(III)) and arsenate (As(V)) removal efficiency of peanut shell biochar (PSB) was compared with peanut shell (PS) in aqueous solutions. Sorption experiments showed that PSB possessed relatively higher As removal efficiency than PS, with 95% As(III) (at pH 7.2) and 99% As(V) (at pH 6.2) with 0.6 g L−1 sorbent dose, 5 mg L−1 initial As concentration, and 2 h equilibrium time. Experimental data followed a pseudo-second-order model for sorption kinetics showing the dominance of chemical interactions (surface complexation) between As and surface functional groups. The Langmuir model for sorption isotherm indicated that As was sorbed via a monolayer sorption process. The X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy analyses revealed that the hydroxyl (–OH) and aromatic surface functional (C=O, C=C–C, and –C–H) groups contributed significantly in the sorption of both As species from aqueous solutions through surface complexation and/or electrostatic reactions. We demonstrate that the pyrolysis of abandoned PS yields a novel, low-cost, and efficient biochar which provides dual benefits of As-rich water treatment and a value-added sustainable strategy for solid waste disposal.
18642. 题目: Maize (Zea mays) growth and nutrient uptake following integrated improvement of vermicompost and humic acid fertilizer on coastal saline soil
期刊: Applied Soil Ecology
作者: Mengli Liu, Chong Wang, Fuyou Wang, Yongjin Xie
摘要: Soil salinity, poor soil structure and macronutrient deficiencies are three important limitations responsible for poor crop yields in coastal saline soil. Therefore, the objective was to investigate the integrated effects of humic acid fertilizer and vermicompost on maize growth and nutrient uptake in coastal saline soil. The experiment included three treatments: (1) control without humic acid fertilizer and vermicompost (CK); (2) treatment with humic acid fertilizer (H); (3) treatment with vermicompost (V). Soil salinity, aggregates, nutrient availability and uptake, the soil microbial community from next-generation high-throughput sequencing, maize biomass and yield were determined in this study. The results showed that humic acid fertilizer and vermicompost increased soil macroaggregates by 77.59–125.58% and 35.02–91.02%, respectively, which could efficiently decrease soil salinity. Proteobacteria, Actinobacteria and Acidobacteria were the dominant bacterial phyla, and Ascomycota was the dominant fungal phylum in this coastal saline soil. The humic acid fertilizer and vermicompost could affect the fungal community structure in the six-leaf stage (6S) and the bacterial community structure in the harvest stage (HS), which consequently improved soil nutrient availability and maize nutrient uptake. The humic acid fertilizer and vermicompost could enhance nitrogen (N) nutrient absorption of the maize plant in the vegetative growth period (6S) and the phosphorus (P) and potassium (K) nutrient absorption in the reproductive growth period (tasseling stage (TS) and harvest stage (HS)) of maize, which played an important role in increasing the maize yield in coastal saline soil. Therefore, the application of humic acid fertilizer and vermicompost can be integrated as a practice for improving coastal saline soil.
18643. 题目: Biochar decreases soil N2O emissions in Moso bamboo plantations through decreasing labile N concentrations, N-cycling enzyme activities and nitrification/denitrification rates
作者: Yuze Song, Yongfu Li, Yanjiang Cai, Shenglei Fu, Yu Luo, Hailong Wang, Chenfei Liang, Ziwen Lin, Shuaidong Hu, Yongchun Li, Scott X. Chang
摘要: Biochar application has been shown to be effective in mitigating soil N2O emission in agricultural soils. However, the effect of biochar on soil N2O emission in subtropical plantations and the underlining mechanisms are poorly understood. The objective of this study was to investigate the effect of biochar application rates (0, 5 and 15 t ha−1) on soil properties and N2O emissions within a Moso bamboo (Phyllostachys edulis) plantation in a 24-month field trial. Biochar application significantly (P < 0.05) decreased soil N2O emission, with the reduction rate positively related to the biochar application rate. The reduction in N2O emission by biochar application diminished over time. Biochar did not affect soil temperature (at 5 cm depth), and there were no significant relationships between N2O emission and either soil moisture content or soil microbial biomass C. However, biochar application significantly (P < 0.05) increased the water soluble organic C but decreased soil NH4+-N, NO3−-N and water soluble organic N (WSON) concentrations, soil urease and protease activities, and soil gross nitrification and denitrification rates. Soil N2O flux was positively (P < 0.05) correlated with soil NH4+-N, NO3−-N and WSON concentrations, soil urease and protease activities, and soil gross nitrification and denitrification rates, regardless of the treatment. Structural equation modeling suggests that biochar application decreased soil N2O emissions directly by decreasing soil gross nitrification and denitrification rates, and indirectly by decreasing concentrations of NH4+-N, NO3−-N and WSON, and the activities of urease and protease. We conclude that biochar application decreased soil N2O emission in the Moso bamboo plantation by decreasing labile N concentrations, N-cycling enzyme activities and nitrification/denitrification rates. Our findings suggest that biochar application can be an effective method to mitigate soil N2O emission in subtropical plantations.
18644. 题目: Aridity-controlled hydrogen isotope fractionation between soil n-alkanes and precipitation in China
期刊: Organic Geochemistry
作者: Yangyang Li, Shiling Yang, Pan Luo, Shangfa Xiong
摘要: Leaf-wax n-alkane hydrogen isotope composition (δDalk) is widely applied as a proxy for paleohydroclimatic changes, but the factors controlling δDalk remain to be clarified. In this study, in order to determine the dominant controls, we measured δDalk in 54 surface soils along a southeast–northwest transect across a steep climatic gradient in China. δDalk is positively correlated with annual precipitation δD (δDpann) and better correlated with growing season (April–October) precipitation δD (δDpgs). However, the variability of δDpann (38‰) and δDpgs (35‰) does not explain all of the variance in δDalk (84‰). The apparent fractionation of hydrogen isotopes between n-alkanes and precipitation (εalk/p) is significantly correlated with variables related to aridity: relative humidity, rainfall amount, and aridity index (defined as the ratio of average precipitation to average potential evapotranspiration). This result demonstrates the important control of aridity on δDalk, which may result from the increasing soil evaporation and plant transpiration, as well as decreasing biosynthetic fractionation, in arid climates. We compiled published δDalk data from surface lake/soil sediments in China, and found that aridity effects are pronounced in regions with mean annual precipitation (MAP) < 800 mm. Therefore, we suggest that soil δDalk reflects precipitation δD modified by aridity, with a greater degree of modification in arid environments (e.g., MAP < 800 mm). Future work to quantitatively determine the effects of aridity on δDalk is needed to improve the reliability of the application of δDalk in paleoenvironmental studies.
18645. 题目: Molecular characteristics of microbially mediated transformations of Synechococcus ‐derived dissolved organic matter as revealed by incubation experiments
期刊: Environmental Microbiology
作者: Qiang Zheng, Qi Chen, Ruanhong Cai, Chen He, Weidong Guo, Yu Wang, Quan Shi, Chang Chen, Nianzhi Jiao
摘要: In this study, we investigated the microbially‐mediated transformation of labile Synechococcus‐derived DOM to RDOM using a 60‐day experimental incubation system. Three phases of TOC degradation activity (I, II, and III) were observed following addition of Synechococcus‐derived DOM. The phases were characterized by organic carbon consumption rates of 8.77, 1.26, and 0.16 μmol L−1 day−1, respectively. Excitation emission matrix analysis revealed the presence of three FDOM components including tyrosine‐like, fulvic acid‐like, and humic‐like molecules. The three components also exhibited differing biological availabilities that could be considered as labile DOM (LDOM), semi‐labile DOM (SLDOM), and RDOM, respectively. DOM molecular composition was also evaluated using FT‐ICR MS. Based on differing biological turnover rates and normalized intensity values, a total of 1,704 formulas were identified as candidate LDOM, SLDOM, and RDOM molecules. Microbial transformation of LDOM to RDOM tended to proceed from high to low molecular weight, as well as from molecules with high to low double bond equivalent (DBE) values. Relatively higher aromaticity was observed in the formulas of RDOM molecules relative to those of LDOM molecules. FDOM components provide valuable proxy information to investigate variation in the bioavailability of DOM. These results suggest that coordinating fluorescence spectroscopy and FT‐ICR MS of DOM, as conducted here, is an effective strategy to identify and characterize LDOM, SLDOM, and RDOM molecules in incubation experiments emulating natural systems. The results described here provide greater insight into the metabolism of phytoplankton photosynthate by heterotrophic bacteria in marine environments.
18646. 题目: Suspended matter and associated contaminants in Danish streams: a national analysis
期刊: Journal of Soils and Sediments
作者: Hans Thodsen, Jes Jessen Rasmussen, Brian Kronvang, Hans Estrup Andersen, Anders Nielsen, Søren Erik Larsen
摘要: Purpose: Suspended matter (SM) in streams is usually considered of minor importance in Danish environmental management. However, SM has some ecological effects as it may (1) clog fish spawning grounds and (2) act as an important agent for transport and exposure of biota to chemical substances, such as phosphorus and toxic inorganic (e.g. heavy metals) and organic (e.g. pesticides) substances. Materials and methods: A large national data set of > 100,000 water samples analysed for SM and loss on ignition was investigated for spatial concentration patterns, sediment yields and temporal trends. Moreover, the importance of SM as a transport agent for phosphorus and heavy metals in streams was investigated through a correlation analysis. Results and discussion: The mean suspended matter concentration (SMC) (including organic matter) amounted to 12 mg l−1, with an organic content of 4.9 mg l−1 (41%). A clear difference in SMC temporal trends over the sampling period was found between geographical regions. Sediment yields were calculated for all major catchments revealing low sediment yields (1–15 t km−2 year−1) compared to neighbouring countries and showed clear geographical patterns. Statistically significant relationships were established between SMCs, suspended sediment concentrations (SSCs) (excluding organic matter) and organic matter concentrations (OMCs) and particulate phosphorus (PP) concentrations, and again spatial patterns appeared. However, it was clearly shown that SMC/SSC/OMC could not be used as a robust, nationwide, indicator for PP concentrations. Analyses of the relationship between SMC and particle-bound heavy metal concentrations generally revealed weak correlations except for Pb and Ni (median R2 > 0.3). Conclusions: Relatively low SM concentrations and sediment yields were found. SM is, in some geographical regions, an important transport agent for PP. Clear geographical patterns occurred in the relationships between SMC/SSC/OMC and both river water discharge and PP, as well as for sediment yields and for temporal trends in SMC.
18647. 题目: Influence of biochar amendment and foliar application of iron oxide nanoparticles on growth, photosynthesis, and cadmium accumulation in rice biomass
期刊: Journal of Soils and Sediments
作者: Muhammad Rizwan, Shamaila Noureen, Shafaqat Ali, Sarwat Anwar, Muhammad Zia ur Rehman, Muhammad Farooq Qayyum, Azhar Hussain
摘要: Purpose: The majority studies used the biochar or nanoparticles alone in metal-contaminated soils while less is known about the combined use of these amendments in metal-contaminated soils. We aimed to explore the efficiency of iron oxide nanoparticles (Fe NPs) and biochar on cadmium (Cd) uptake in rice in pot trial. Materials and methods: An experiment was performed under ambient environmental conditions in a Cd-contaminated soil with and without biochar addition (1.0% w/w), and different Fe NP concentrations (0, 10, 20, 30 mg/L) were foliar sprayed at different time intervals (at 3rd, 4th, and 5th weeks of nursery transplantation in the pots) during the plant growth. After harvesting, rice growth, photosynthesis, Cd and Fe contents in rice tissues, and soil bioavailable Cd and soil pH were measured. Results and discussion: Iron NPs enhanced the dry weights of rice tissues, chlorophyll concentrations, and gas exchange characteristics and the impact of NPs was further increased when the biochar was applied along with NPs. Iron NPs significantly decreased the intake of Cd in rice shoots by 31 and 42% and in rice roots by 26 and 39% with the foliar spray of Fe NPs (30 mg/L) without and with biochar, respectively. Foliar spray of Fe NPs reduced the total Cd accumulation by shoots, whereas the total Cd accumulation in the roots increased. The co-presence of Fe NPs and Cd enhanced the Fe concentrations in shoots of rice by 52 and 33% and in roots of rice by 32 and 21% when 30 mg/L Fe NPs were supplied with and without biochar, respectively. The effects of Fe NPs were higher with biochar application than without biochar except Fe concentrations in rice seedlings where the opposite trend was observed. Conclusions: The increase in biomass, Fe concentrations in tissues, and decrease in Cd levels in plants clearly demonstrate that Fe NPs + biochar could be a promising technique for the utilization of Cd-contaminated soils in the future.
18648. 题目: Biochar addition increases subsurface soil microbial biomass but has limited effects on soil CO2 emissions in subtropical moso bamboo plantations
期刊: Applied Soil Ecology
作者: Xiaogai Ge, Yonghui Cao, Benzhi Zhou, Xiaoming Wang, Zhenya Yang, Mai-He Li
摘要: Biochar addition affects soil conditions and soil microorganisms, and it may reduce soil CO2 emissions. However, knowledge on how biochar addition induces the changes in soil microbial communities with soil depth and time and affects soil respiration is limited in forest ecosystems. We investigated the effects of biochar addition on soil respiration rate and its sensitivity to soil temperature and microbial community composition in moso bamboo (Phyllostachys eduis) plantations in subtropical China for two years. We set up four treatments of biochar addition onto the soil surface of the plantations with the level of 0 (control, CK), 5 (low biochar, LB), 10 (medium biochar, MB), or 20 t biochar ha−1 (high biochar, HB) in April 2014. Biochar addition significantly improved soil moisture at 5 cm soil depth but did not affect soil temperature. Microbial biomass increased significantly with biochar addition at 10–20 cm soil depth but showed no response in the 0–10 cm depth soil layer. Compared to CK, biochar addition significantly affected the mean soil respiration rate during the two–year experiment, but the difference between CK and biochar treatments decreased both with time following biochar addition and with increasing biochar dosage. Annual cumulative soil respiration was significantly and positively correlated with the biomass of total PLFAs, gram-negative bacteria, bacteria, and arbuscular mycorrhizal fungi (P < 0.05) at 0–10 cm soil depth but not at 10–20 cm. Overall, only LB significant decreased the total CO2 emissions. Our results suggest that lower dosage additions of biochar have a positive effect in reducing total CO2 emissions and promote soil organic carbon sequestration in bamboo forests in subtropical China.
18649. 题目: Seasonal changes in labile organic matter as a function of environmental factors in a relict permafrost region on the Qinghai-Tibetan Plateau
作者: Guimin Liu, Xiaolan Zhang, Tonghua Wu, Xiaoli Wu, Joseph M. Smoak, Xinxing Li, Genghao Ji, Haiyan Xu, Xiaoliang Ma, Hongqin Li, Guangyang Yue, Yongjian Ding, Lin Zhao, Xiaodong Wu
摘要: Labile organic matter plays an important role in permafrost carbon cycling, however, little is known about the effects of permafrost on labile organic matter dynamics. Here, we examined seasonal changes in the labile organic matter including light fraction carbon (LFC), water extractable organic carbon (WEOC), microbial biomass carbon (MBC) and nitrogen (MBN) contents in a relict permafrost region on the eastern edge of the Qinghai-Tibetan Plateau (QTP), China. We selected three different areas including permafrost, boundary, and seasonally frozen ground area. The results showed that seasonal changes in labile organic matter were not the result of soil heterogeneity. Among all three areas, depth strongly correlated with labile organic matter content. LFC was significantly associated with the soil organic carbon (SOC) content. The MBC contents, which were the lowest in permafrost area but highest in seasonally frozen ground area, were strongly affected by temperature. Multiple linear regression models showed that temperature was a significant predictor for labile organic matter in the permafrost area, but the effects of temperature were weaker in the boundary and seasonally frozen ground areas. Our results suggested that permafrost degradation could decrease production but increase decomposition rates of labile organic matter in permafrost regions, and this process should be taken into consideration in permafrost carbon cycle models.
18650. 题目: Pyrolysis biochar has negligible effects on soil greenhouse gas production, microbial communities, plant germination, and initial seedling growth
作者: Elizabeth Meschewski, Nancy Holm, Brajendra K. Sharma, Kurt Spokas, Nicole Minalt, John J. Kelly
摘要: Biochar has been promoted as a soil amendment that enhances soil quality and agronomic productivity and reduces greenhouse gas production. However, these benefits are not always realized. A major hurdle to the beneficial use of biochar is our limited knowledge regarding the mechanisms directing its effects on soil systems. This project aimed to eliminate some of this uncertainty by examining the biological responses (plant productivity, greenhouse gas production, soil microbial community structure) of a suite of soils (10) to the addition of biochars produced by different processes (pyrolysis, gasification, burning) from a range of feedstocks (corn stalks, hardwood, grass). Results indicated that these three responses were not significantly impacted by the addition of pyrolysis biochars from different feedstocks at 1 and 5% (w/w) addition levels. On the other hand, both an open-air burned corn stalk (5%) and raw corn stalks (1 and 5%) additions did alter the measured soil functionality. For example, the 5% burnt corn stalks addition reduced total above ground plant biomass (∼30%), increased observed N2O production by an order of magnitude, and altered soil bacterial community structure. The bacterial groups that increased in relative abundance in the burnt corn stalks-amended soils included families associated with cellulose decomposition (Chitinophagaceae), plant pathogens (Xanthomonadaceae), and biochar/charcoal-amended media (Gemmatimonadetes). In contrast, the abundance of these bacterial groups was not impacted by the pyrolysis biochars. Therefore, this research suggests that pyrolysis biochar represents a stabilized form of carbon that is resistant to microbial mineralization and has negligible effects on soil biological responses.
18651. 题目: Combination of DGT and fluorescence spectroscopy for improved understanding of metal behaviour in mangrove wetland
作者: Haoliang Lu, Degang Mei, Mitchell Pavao-Zuckerman, Qiang Wang, Hualong Hong, Shengjie Wu, Mingyi Xu, Xudong Zhu, Jingchun Liu, Chongling Yan
摘要: Understanding bioavailable metal behaviour in situ is critical for pollution evaluation and contaminant management in mangrove wetland. Here, the diffusive gradients in thin films technique (DGT) was used for characterizing the (bio)available portions of Cr, Zn, Pb, Cu, Fe and Mn in two mangrove wetlands affected by industrial waste discharges (Jiulong Estuary) and domestic discharges (Zhangjiang Estuary), in Fujian Province, China. In addition, fluorescence excitation emission matrices-parallel factor analysis (EEM-PARAFAC) was applied for characterizing the occurrence and behaviour of dissolved organic matter (DOM) in soil solution, as well as their feasibility for assessing behaviours of metals. The results demonstrated that the combination of DGT and EEM, which are well suitable for studying DOM impacted metal behaviors in mangrove sediments. Discharge of difference wastewater into the mangrove wetlands of Jiulong and Zhangjiang Estuaries, gave rise to the DGT-labile metal concentration of Zn > Cu > Cr > Pb and Zn > Cr > Pb > Cu, respectively. A variety of humic-like fluorescent components was characterized here, providing valuable insights into the chemical composition of DOM in rhizosphere and bulk sediment. Terrestrial humic-like compounds indicated a different binding affinity for heavy metals in mangrove sediments. These findings are useful for the future understanding of the metal speciation and molecular binding mechanisms in such mangrove wetlands.
18652. 题目: Adsorption kinetics and aggregation for three classes of carbonaceous adsorbents in the presence of natural organic matter
作者: Gamze Ersan, Yasemin Kaya, Mahmut S. Ersan, Onur G. Apul, Tanju Karanfil
摘要: In this study, adsorption kinetics of phenanthrene (PNT) and trichloroethylene (TCE) by a graphene nanosheet (GNS), a graphene oxide nanosheet (GO), a single-walled carbon nanotube (SWCNT), a multi-walled carbon nanotube (MWCNT), and two coal based activated carbons (ACs) (F400 and HD3000) were examined in distilled and deionized water (DDW) and under natural organic matter (NOM) preloading conditions. The results showed the times needed for the adsorption of PNT and TCE to reach apparent equilibrium (i.e., ≤3% change per day) followed the order of GO ≥ MWCNT > GNS > SWCNT ∼ HD3000 ∼F400 and SWCNT > GNS ∼ HD3000 > F400 ∼ MWCNT > GO, respectively. The pseudo second order model successfully represented kinetics data for three classes of carbonaceous adsorbents. The Weber-Morris intraparticle diffusion model indicated three steps adsorption process for PNT and two step adsorption for TCE. In addition, the times needed to reach apparent equilibrium for the adsorption of PNT and TCE in the presence of hydrophobic (HPO) and hydrophilic (HPI) NOM solutions increased for all adsorbents (except for GO). In general, both NOM showed similar impacts on the adsorption rates of PNT and TCE. Aggregation of both GNS and CNTs rapidly occurred during initial couple hours of contact time during preloading, and spiking both PNT and TCE further increased their aggregation.
18653. 题目: Spatial and temporal variability of sandy intertidal macrobenthic communities and their relationship with environmental factors in a tropical island
期刊: Estuarine, Coastal and Shelf Science
作者: Vikas Pandey, Ganesh Thiruchitrambalam
摘要: Spatial and temporal variability of macrobenthic community in intertidal habitats is governed by various physicochemical factors. Finding the relationship between environmental parameters and the biotic element of an ecosystem have been the centre of ecological studies. This paper describes the influence of environmental parameters in structuring the benthic community at spatial and temporal scales. Samplings were carried out on seasonal basis for a period of two years (August 2013 to July 2015). Fauna was collected from three soft-bottom intertidal locations (CH, MP and CT) using 25 × 25 cm quadrat along the Port Blair coast, south Andaman, India. A total of 112 macrofaunal taxa belonging to 4 major and 2 minor phyla were recorded. Polychaeta was the most dominant taxa followed by Amphipoda. Statistical analyses revealed that macrobenthic faunal assemblages were significantly different at spatial scale but not on temporal pattern. The distribution of macrobenthic fauna at spatial scale was mainly influenced by sediment characteristics (organic matter and grain size). Amphipods dominated the locations where sediment having coarser grain size and low organic matter whereas polychaetes and molluscs were found abundant at the locations characterised with fine sediment and high organic matter. This study concludes that in the regions where temporal variability is not significant, the sediment characteristics, which together with beach morphodynamics play an important role in structuring the benthic community.
18654. 题目: An emerging environmental concern: Biochar-induced dust emissions and their potentially properties
期刊: Science of The Total Environment
作者: Danielle Leigh Gelardi, Chongyang Li, Sanjai J. Parikh
摘要: Amending soils with biochar is increasingly proposed as a solution to many pressing agricultural and environmental challenges. Biochar, created by thermochemical conversion of biomass in an oxygen-limited environment, has several purported benefits, including remediation of contaminated soils, increased crop yields, reduced fertilizer demands, increased plant available water, and mitigation of climate change. Due to these potential benefits, biochar-related research has flourished in the past decade, though there remains a critically understudied area of research regarding biochar's potential impact on human health. Because biochar characteristically has low bulk density and high porosity, the material is susceptible to atmospheric release via natural or mechanical soil disturbance. The specific risks of biochar inhalation have not been elucidated; however, recent publications have demonstrated that biochar can increase soil dust emissions of particles <10 μm (PM10) or possess elevated levels of toxic chemicals. These data should not be interpreted to suggest that all biochars are problematic, but rather to highlight an important and overlooked field of study, and to stress the need to critically assess parameters for biochar production and management strategies that safeguard human health. Here the literature on biochar-related dust emissions and potentially toxic properties (PTPs) is reviewed in order to summarize what is known, highlight areas for future study, and aggregate solutions to minimize potential harm.
18655. 题目: Nagasaki sediments reveal that long-term fate of plutonium is controlled by select organic matter moieties
期刊: Science of The Total Environment
作者: Peng Lin, Chen Xu, Daniel I. Kaplan, Hongmei Chen, Chris M. Yeager, Wei Xing, Luni Sun, Kathleen A. Schwehr, Hideo Yamazaki, Yoko Saito-Kokubu, Patrick G. Hatcher, Peter H. Santschi
摘要: Forecasting the long-term fate of plutonium (Pu) is becoming increasingly important as more worldwide military and nuclear-power waste is being generated. Nagasaki sediments containing bomb-derived Pu that was deposited in 1945 provided a unique opportunity to explore the long-term geochemical behavior of Pu. Through a combination of selective extractions and molecular characterization via electrospray ionization Fourier-transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS), we determined that 55 ± 3% of the bomb-derived 239,240Pu was preferentially associated with more persistent organic matter compounds in Nagasaki sediments, particularly those natural organic matter (NOM) stabilized by Fe oxides (NOMFe-oxide). Other organic matter compounds served as a secondary sink of these bomb-derived 239,240Pu (31 ± 2% on average), and <20% of the 239,240Pu was immobilized by inorganic mineral particles. In a narrow, 239,240Pu-enriched layer of only 9-cm depth (total core depth was 600 cm), N-containing carboxyl aliphatic and/or alicyclic molecules (CCAM) in NOMFe-oxide and other NOM fractions immobilized the majority of 239,240Pu. Among the cluster of N-containing CCAM moieties, hydroxamate siderophores, the strongest known Pu chelators in nature, were further detected in these “aged” Nagasaki bomb residue-containing sediments. While present long-term disposal and environmental remediation modeling assume that solubility limits and sorption to mineral surfaces control Pu subsurface mobility, our observations suggest that NOM, which is present in essentially all subsurface systems, undoubtedly plays an important role in sequestrering Pu. Ignoring the role of NOM in controlling Pu fate and transport is not justified in most environmental systems.
18656. 题目: Microbial mechanisms of the contrast residue decomposition and priming effect in soils with different organic and chemical fertilization histories
期刊: Soil Biology and Biochemistry
作者: Fenliang Fan, Bing Yu, Boren Wang, Timothy S. George, Huaqun Yin, Dongchu Li, Alin Song
摘要: We integrated chemical, enzymatic, isotopic and molecular approaches to investigate both straw decomposition and its priming effect (PE) on native soil organic carbon (SOC) decomposition in soils with 23 years of application of chemical fertilizer (NPK) and partial substitution of chemical fertilizer by organic manure (NPKM). We found that NPK and NPKM past application significantly increased decomposition of straw. The increases in straw decomposition were not correlated with the abundances of microbiome assimilating straw carbon, but were significantly correlated with abundances of total bacteria, fungi and activities of cellulose-degrading enzymes. In addition, application of NPK did not change straw-induced PE while application of NPKM markedly reduced PE. The variation of PE with different past fertilization was correlated with the abundance of residue-stimulated fungi. The unchanged PE with NPK application in the presence of enriched nutrients and reduced pH was probably due to residue-promoted growth of acid-tolerant SOC-decomposing taxa (unclassified bacteria families belong to Acidobacteria GP3, Gamaproteobacteria and WPS-2 and unclassified fungal families belong to Chaetothyriales and Agaricomycetes). Our research sheds light on the complex processes of carbon transformation in the soils undergoing different long-term nutrient management.
18657. 题目: Variations in soil and plant-microbiome composition with different quality irrigation waters and biochar supplementation
期刊: Applied Soil Ecology
作者: Erping Cui, Xiangyang Fan, Zhongyang Li, Yuan Liu, Andrew L. Neal, Chao Hu, Feng Gao
摘要: To reduce water scarcity in China, the use of reclaimed water or anaerobically treated piggery wastewater, either alone or coupled with biochar supplementation, is attracting increasing attention. However, little information is available regarding their effects on the soil and plant microbiomes receiving irrigation. The objective of this study was to evaluate different water quality irrigation (distilled water, reclaimed water, and piggery wastewater), biochar supplementation, and their interactions on the microbiomes of rhizosphere and bulk soil, and the root endosphere of maize using high-throughput 16S rRNA amplicon sequencing. The experiments were conducted in greenhouse rhizoboxes. The microbiome functional potentials were predicted using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt). After a 60-day cultivation period, the bacterial communities and potential functions of rhizosphere, bulk soil, and root endosphere displayed distinct differences between irrigation water sources. Irrigation water quality and biochar supplementation influenced bacterial diversity in rhizosphere soil, and bacterial composition was more sensitive to irrigation water quality than to biochar supplementation in soil and root samples. Reclaimed water and piggery wastewater irrigation decreased the abundance of putative plant growth-promoting rhizobacteria (PGPR) and increased the abundance of known pathogenic bacteria. Biochar supplementation elicited the same behaviour. Mantel tests indicated that soil pH and available P exerted strong influences on the structure of the bacterial community in rhizosphere and bulk soil, but total N significantly influenced the bacterial community structure within the root. The current study implies the potential ecological effects (e.g. PGPR and pathogenic bacteria) of the irrigation with different quality water should be considered with biochar supplementation.
18658. 题目: Short-term dynamics of soil organic matter fractions and microbial activity in smallholder potato-legume intercropping systems
期刊: Applied Soil Ecology
作者: Shadrack O. Nyawade, Nancy N. Karanja, Charles K.K. Gachene, Harun I. Gitari, Elmar Schulte-Geldermann, Monica L. Parker
摘要: Continuous cultivation of potato (Solanum tuberosum L.) in monoculture systems represents the greatest factor deteriorating soil organic matter (SOM) in smallholder farms. With an aim to breaking this norm, a 2-year field trial intercropping potato with two legumes: lima bean (Phaseolus lunatus) and dolichos (Lablab purpureus), was conducted in the upper-midland (1552 meters above sea level (masl.)), lower-highland (1854 masl.) and upper-highland (2552 masl.) agro-ecologies of Kenya. Residues from each cropping system were quantified at the end of each season and incorporated back into the soil at start of the subsequent season. A combined physical and density fractionation was used to separate the soil in macro-aggregates (>250 μm), micro-aggregates (250–50 μm) and silt plus clay fractions (<50 μm), while SOM was partitioned into labile (density of 1.65 to 1.85 g cm−3) and stable (2.60 g cm−3) fractions. Microbial biomass contents were determined by chloroform fumigation while enzymatic activities were assessed by hydrolyses of fluorescein diacetate and dehydrogenase. Compared to sole potato, intercropping increased the contents of light fraction organic matter by 12–28%, dissolved organic matter by 7–21% and microbial biomass by 15–38%, thus stimulating enzyme activities. Trends in soil microbial respiration followed those of enzyme activity and were 20–34% higher in intercropping than in sole potato. Intercropping ensured high residue returns which got short-term residence within the macro-aggregates, thus ensuring steady supply of substrates to the soil microbes. These results affirm legume intercropping as a possible entry point to restoring the impoverished soil quality in smallholder potato farming systems.
18659. 题目: Iron and carbon granules added to anode enhanced the sludge decrement and electrical performance of sludge microbial fuel cell
期刊: Chemical Engineering Journal
作者: Lu Cai, Hanmin Zhang, Yujie Feng, Bin Dong, Yuezhu Wang, Chengcheng Ge
摘要: Sludge microbial fuel cell (SMFC) can utilize the organics in sludge to generate power, and has attracted widespread attention. However, the low efficiency of organics utilization and limited power-output are the main challenges that need to be addressed. This study proposed an in situ method without additional energy to enhance the performance of SMFC by adding the package of iron and carbon granules (FeC). In the reactors including FeC-SMFC (the FeC package placed under the carbon felt anode and separated from the closed-circuit), FeC-OSMFC (FeC-SMFC in open-circuit), and FeCSMFC (the FeC package attached to the anodic bottom and closed-circuit), the degradation of refractory organics especially humic acid-like substances was significantly promoted, due to the FeC micro-electrolysis at neutral pH. More organics were beneficial for the enrichment of typical exoelectrogens belonging to Proteobacteria and Firmicutes, thereby improving the electrical performance of FeC-SMFC and FeCSMFC, compared with normal SMFC without FeC package (NSMFC). In FeCSMFC, the soluble and total chemical oxygen demand removal efficiencies were 65.60% and 52.64%. The removal efficiency of volatile suspended solids in FeCSMFC was 69.26%, which was 30.05%, 14.97%, 9.87% and 6.62% higher than that in open-circuit SMFC, NSMFC, FeC-OSMFC and FeC-SMFC, respectively. The power output of FeCSMFC was 37.28 W m−3, 6.06 and 1.76 times higher than that of NSMFC and FeC-SMFC, respectively. The addition of FeC package to anode is a cost-saving and effective method to enhance electricity generation and sludge decrement of SMFC.
18660. 题目: Impact of background water quality on disinfection performance and silver release of immobilized silver nanoparticles: Modeling disinfection kinetics, bactericidal mechanism and aggregation behavior
期刊: Chemical Engineering Journal
作者: Shekhar Agnihotri, Soumyo Mukherji, Suparna Mukherji
摘要: An aminosilane-based surface functionalization strategy was adopted to immobilize silver nanoparticles (AgNPs) on to silica materials to minimize leaching of silver into the aqueous environment. The disinfection potential and silver release of immobilized-AgNPs and chloridized silver surfaces were investigated for simulated lake water under varying water chemistry conditions. While the presence of both hardness and natural organic matter (NOM) adversely affected the disinfection kinetics and silver release from immobilized-AgNPs, alkalinity had only minor impact on disinfection performance over the concentration range 30–600 mg L−1. The higher disinfection efficacy of immobilized-AgNPs was ascribed to their contact-killing mechanism of action. In contrast, chloridized Ag that caused disinfection through the release of silver ions showed lower disinfection efficacy. Divalent cations and NOM greatly influenced the surface characteristics and morphology of the immobilized-AgNPs. However, immobilized AgNPs were more shielded than colloidal AgNPs when exposed to similar harsh conditions characterized by high hardness and NOM concentration. Under all the tested conditions, where 100% disinfection was achieved, the amount of silver release from immobilized AgNPs was less than 22 µg L−1, which is well below the USEPA permissible limit. The disinfection kinetics of immobilized-AgNPs was best fitted by the Hom model (R2 = 0.974), where its lumped parameters kh and m were found to vary with variation in background water quality. Sensitivity analyses indicated that for ‘m’ value higher than 1.9, complete disinfection could not be achieved regardless of many fold increase in ‘kh’ value.