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26461. 题目: Linking shifts in bacterial community with changes in dissolved organic matter pool in a tropical lake
文章编号: N19041004
期刊: Science of The Total Environment
作者: Marcelo P. Ávila, Luciana P.M. Brandão, Ludmila S. Brighenti, Denise Tonetta, Mariana P. Reis, Peter A. Stæhr, Eero Asmala, André M. Amado, Francisco A.R. Barbosa, José F. Bezerra-Neto, Andréa M.A. Nascimento
更新时间: 2019-04-10
摘要: Bacterioplankton communities have a pivotal role in the global carbon cycle. Still the interaction between microbial community and dissolved organic matter (DOM) in freshwater ecosystems remains poorly understood. Here, we report results from a 12-day mesocosm study performed in the epilimnion of a tropical lake, in which inorganic nutrients and allochthonous DOM were supplemented under full light and shading. Although the production of autochthonous DOM triggered by nutrient addition was the dominant driver of changes in bacterial community structure, temporal covariations between DOM optical proxies and bacterial community structure revealed a strong influence of community shifts on DOM fate. Community shifts were coupled to a successional stepwise alteration of the DOM pool, with different fractions being selectively consumed by specific taxa. Typical freshwater clades as Limnohabitans and Sporichthyaceae were associated with consumption of low molecular weight carbon, whereas Gammaproteobacteria and Flavobacteria utilized higher molecular weight carbon, indicating differences in DOM preference among clades. Importantly, Verrucomicrobiaceae were important in the turnover of freshly produced autochthonous DOM, ultimately affecting light availability and dissolved organic carbon concentrations. Our findings suggest that taxonomically defined bacterial assemblages play definite roles when influencing DOM fate, either by changing specific fractions of the DOM pool or by regulating light availability and DOC levels.
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26462. 题目: Dynamics and temperature sensitivity of soil organic carbon mineralization under medium-term conservation agriculture as affected by residue and nitrogen management options
文章编号: N19041003
期刊: Soil and Tillage Research
作者: S.L. Jat, C.M. Parihar, A. Dey, H.S. Nayak, A. Ghosh, N. Parihar, A.K. Goswami, A.K. Singh
更新时间: 2019-04-10
摘要: In the scenario of global climate change, the enhancement and stabilization of soil organic carbon holds prime importance. In this context, conservation agriculture (CA) based practices i.e., diversified cropping systems and permanent bed (PB) holds great potential. In this article, we have compared the dynamics of soil organic carbon under mustard and wheat based systems [MMuMb, maize-mustard-mungbean and MWMb, maize-wheat-mungbean)] planted on PB, with and without residue (PB + R and PB - R) along with four nitrogen (N) management options [Un-fertilized, N through prilled urea (PU), N through sulphur coated urea (SCU), and N through neem coated urea (NCU)]. After 5-years of experimentation, to assess the medium-term impact of full CA (PB + R) in comparison to partial CA (PB-R) on SOC dynamics under mustard and wheat based systems with diverse N sources, we had conducted an incubation study at three temperature levels (27, 32 and 37 °C) in a sandy loam soil (Typic Haplustept) of north-western Indo- Gangetic Plains (IGP) of India. Wheat-based cropping system (MWMb) resulted in higher values of less labile, non-labile as well as total SOC, as compared with mustard-based system (MMuMb). On the other hand, MMuMb registered higher amount of very labile and labile SOC, with enhanced decay rate. The cumulative C mineralization (Ct) was 11–17% higher under MMuMb compared with MWMb, from all the soil depths at 27 °C. Retention of crop residue in PB increased total SOC by 11.5 to 19.5% compared with PB-R, across the soil depths. The Ct were significantly higher under full CA plots with lower decay rate (Kc), as compared to plots under partial CA. Application of N fertilizers registered a significant hike in total SOC compared to un-fertilized control plots. At the same time, the coated N sources i.e., SCU and NCU failed to cause any significant improvements in total SOC as compared with uncoated PU plots. On the other hand, coated urea treated plots registered significantly higher C mineralization compared with uncoated PU plots. Between the two coated urea products, the NCU application registered significantly higher C mineralization compared with SCU across the sampling events and temperature regimes from all the soils layers. Cropping system or residue addition/removal did not affect temperature sensitivity of SOC mineralisation. At the same time, addition of N-fertilizers, irrespective of sources lowered the Q₁₀ compared with no-N fertilization.

26463. 题目: Dynamics and Sequestration Potential of Soil Organic Carbon and Total Nitrogen Stocks of Leguminous Green Manure-Based Cropping Systems
文章编号: N19041002
期刊: Soil and Tillage Research
作者: Zhiyuan Yao, Dabin Zhang, Na Liu, Pengwei Yao, Na Zhao, Yangyang Li, Suiqi Zhang, Bingnian Zhai, Donglin Huang, Zhaohui Wang, Weidong Cao, Sina Adl, Yajun Gao
更新时间: 2019-04-10
摘要: Estimating the dynamics and future sequestration potential of soil organic carbon stocks (SOCS) and total nitrogen stocks (TNS) is useful to determine whether cropping systems can promote sustainable production in terms of improving soil fertility. The Rothamsted Carbon (RothC) model and the correlations between SOCS and TNS were used to estimate the future SOCS and TNS of green manure-based wheat production systems on the Loess Plateau of China. The field study was a split-plot design with 4 main treatments (Huai bean, soybean and mung bean grown as green manure in summer, with a fallow treatment as the control) and 4 subtreatments (synthetic N rates of 0, 108, 135 and 162 kg ha⁻¹ applied at wheat sowing). Leguminous green manure (LGM) treatments increased the amount of carbon and nitrogen returned to the field by 67–91% and 74–125%, respectively, compared with the fallow treatment (P < 0.05). These treatments also increased SOCS by 15–23% and TNS by 12–22% (P < 0.05) after 8 years in comparison with the fallow treatment. Coupling of the RothC model and the correlations between SOCS and TNS of the 3 LGM treatments generated acceptable simulations for the dynamics of SOCS and TNS. The projected SOCS for LGM and fallow treatments at the new equilibrium are 37.67–47.29 and 13.97–17.58 Mg ha⁻¹, respectively. The corresponding TNS for LGM treatments are 5.42–6.79 Mg ha⁻¹. The projection also indicates that under the LGM treatments, the SOCS and TNS at the new equilibrium will be 107% and 158% higher, respectively, than the baseline level. In conclusion, growing LGM to replace summer fallow would be a useful alternative to improve soil fertility and promote sustainable crop production.

26464. 题目: Warming increases microbial residue contribution to soil organic carbon in an alpine meadow
文章编号: N19041001
期刊: Soil Biology and Biochemistry
作者: Xueli Ding, Shengyun Chen, Bin Zhang, Chao Liang, Hongbo He, William R. Horwath
更新时间: 2019-04-10
摘要: The contribution of microbial residues to soil organic carbon (SOC) is a process highly influenced by soil properties. We evaluated the presence of microbial amino sugar residues in soil (0–50 cm) of control and warmed plots in an alpine meadow on the Qinghai-Tibet Plateau. Alpine grasslands in the Qinghai-Tibet Plateau store large amounts of soil C and are highly vulnerable to climate change. Results showed that warming significantly increased total microbial residues across the 0–50 cm soil depth. The proportion of microbial-derived C to SOC significantly increased in warmed plots (52% on average) by soil depth compared to the control (38%). Higher microbial turnover and selective preservation into organo-mineral complexes likely explains the observed result. Given insignificant change in total SOC, our results infer an alteration of the SOC source configuration (microbial-derived vs. plant-derived). The observed greater magnitude of warming effects on fungal residues compared to bacterial illustrate a distinct community response to warming. We conclude that warming has the potential to influence soil C sequestration through increased microbial residue inputs, consequently altering its composition and source configuration. Our work provides valuable insights at the molecular level to identify mechanisms of microbial-mediated C processes that are influenced by climate change in high elevation ecosystems.

26465. 题目: Transport and retention of differently coated CeO 2 nanoparticles in saturated sediment columns under laboratory and near-natural conditions
文章编号: N19040912
期刊: Environmental Science and Pollution Research
作者: Laura Degenkolb, Urs Dippon, Silke Pabst, Sondra Klitzke
更新时间: 2019-04-09
摘要: Where surface-functionalized engineered nanoparticles (NP) occur in drinking water catchments, understanding their transport within and between environmental compartments such as surface water and groundwater is crucial for risk assessment of drinking water resources. The transport of NP is mainly controlled by (i) their surface properties, (ii) water chemistry, and (iii) surface properties of the stationary phase. Therefore, functionalization of NP surfaces by organic coatings may change their fate in the environment. In laboratory columns, we compared the mobility of CeO₂ NP coated by the synthetic polymer polyacrylic acid (PAA) with CeO₂ NP coated by natural organic matter (NOM) and humic acid (HA), respectively. The effect of ionic strength on transport in sand columns was investigated using deionized (DI) water and natural surface water with 2.2 mM Ca²⁺ (soft) and 4.5 mM Ca²⁺ (hard), respectively. Furthermore, the relevance of these findings was validated in a near-natural bank filtration experiment using HA-CeO₂ NP. PAA-CeO₂ NP were mobile under all tested water conditions, showing a breakthrough of 60% irrespective of the Ca²⁺ concentration. In contrast, NOM-CeO₂ NP showed a lower mobility with a breakthrough of 27% in DI and < 10% in soft surface water. In hard surface water, NOM-CeO₂ NP were completely retained in the first 2 cm of the column. The transport of HA-CeO₂ NP in laboratory columns in soft surface water was lower compared to NOM-CeO₂ NP with a strong accumulation of CeO₂ NP in the first few centimeters of the column. Natural coatings were generally less stabilizing and more susceptible to increasing Ca²⁺ concentrations than the synthetic coating. The outdoor column experiment confirmed the low mobility of HA-CeO₂ NP under more complex environmental conditions. From our experiments, we conclude that the synthetic polymer is more efficient in facilitating NP transport than natural coatings and hence, CeO₂ NP mobility may vary significantly depending on the surface coating.

26466. 题目: Kinetic aspects of humic substances derived from macrophyte detritus decomposition under different nutrient conditions
文章编号: N19040911
期刊: Environmental Science and Pollution Research
作者: Flávia Bottino, Marcela Bianchessi Cunha-Santino, Irineu Bianchini
更新时间: 2019-04-09
摘要: Autochthonous particulate organic carbon (POC) is an important precursor of humic substances (HS), and macrophytes represent the major source of POC in tropical aquatic ecosystems. Autochthonous HS influence the carbon supply, light regime, and primary production within freshwater systems. This study addresses the conversion of POC from two macrophyte species into HS and their mineralization under different nutrient conditions (oligotrophic to hypereutrophic). A first-order kinetic model was adopted to describe the conversion routes. The POC conversion rate to HS for detritus derived from Paspalum repens was similar under different nutrient conditions, but eutrophication decreased the k_R (global coefficient reaction) for detritus from Pistia stratiotes due to its high detritus quality (C:N:P ratio). Fulvic acids were the main fraction of HS in both plants. The mineralization of humic acids from P. stratiotes was inhibited at higher nutrient availability, while eutrophication increased the mineralization of fulvic acids from P. repens. The main route of POC cycling is humification through fulvic acid formation (up to 40% of POC). The intrinsic characteristics of the source detritus were the main forcing functions that stimulated the cycling of HS. In tropical aquatic ecosystems, the degradation of autochthonous carbon decreased due to eutrophication, thus contributing to the diagenetic process in the long term.

26467. 题目: Penetration of Bomb 14C into the Deepest Ocean Trench
文章编号: N19040910
期刊: Geophysical Research Letters
作者: Ning Wang, Chengde Shen, Weidong Sun, Ping Ding, Sanyuan Zhu, Weixi Yi, Zhiqiang Yu, Zhongli Sha, Mei Mi, Lisheng He, Jiasong Fang, Kexin Liu, Xiaomei Xu, Ellen R.M. Druffel
更新时间: 2019-04-09
摘要: The food source of hadal endemic fauna provides an insight into the carbon cycle in trenches and a biological adaptation to the impoverished and harsh trench environment. Here, we present the first Δ¹⁴C results of hadal amphipods from three trenches in the Pacific to define the organic matter source in these remote ecosystems. Amphipod muscle tissues contain a bomb ¹⁴C signature (Δ¹⁴C from 10±2 ‰ to 65±2 ‰), thereby revealing a dietary preference for labile and fresh organic matter derived from the surface water. Thus, the carbon cycle in the deepest ocean trench has a tight linkage with the surface ocean via the food chain. The bomb ¹⁴C dating result suggests that hadal amphipods have a low tissue turnover rate and an unexpectedly long lifetime (>10 yr), at more than four times higher than the common longevity (~2 yr) of amphipods in shallow waters.

26468. 题目: Coupling and decoupling of soil carbon and nutrient cycles across an aridity gradient in the drylands of northern China: evidence from ecoenzymatic stoichiometry
文章编号: N19040909
期刊: Global Biogeochemical Cycles
作者: Jiao Feng, Kai Wei, Zhenhua Chen, Xiaotao Lü, Jihui Tian, Chao Wang, Lijun Chen
更新时间: 2019-04-09
摘要: Drylands are characterized by stressful conditions with the limitation of both carbon (C) and nutrients, particularly nitrogen (N) and phosphorus (P). Biological C, N and P releases from soil organic matter by enzymes are essential components for biogeochemical cycles and are sensitive to the climate in drylands. However, how the ecoenzymatic C:N:P stoichiometry responds to environmental factors (i.e., climatic and edaphic factors) over broad geographical scales remains largely unclear. We examined the patterns of ecoenzymatic C:N:P ratios across a 3700‐km aridity gradient (0.43<aridity<0.97) in northern China. In wetter sites (aridity<0.70), the relative C:N:P acquisition ratios via enzymes remained relatively constant with increasing aridity. In contrast, in drier sites (aridity>0. 70), the enzymatic C:nutrient (N and P) ratios declined as the aridity increased, while the enzymatic P:N ratios were mostly lower than those in the wetter sites. In drier sites with low C availability, the increasing carbon use efficiency and the increasing proportion of C converted to biomass (than the proportion of respiration) contributed to the declines of the enzymatic C:nutrient ratios as the aridity increased. The overall lower enzymatic P:N ratios were related to the higher soil P availability compared with N availability (higher organic P and lower soil NH₄⁺:Available P ratios) in drier sites. Overall, our findings indicate that intrinsic linkages of biological C, N and P acquisitions and cycles were broken at the aridity threshold of 0.70, with higher acquisition efforts for N and P (particularly for N) with increasing aridity in drier sites with aridity>0.70.

26469. 题目: Identification of environmental factors controlling phosphorus fractions and mobility in restored wetlands by multivariate statistics
文章编号: N19040908
期刊: Environmental Science and Pollution Research
作者: Hu Cui, Yang Ou, Lixia Wang, Haitao Wu, Baixing Yan, Lu Han, Yingxin Li
更新时间: 2019-04-09
摘要: Phosphorus is a dominant environmental factor in fostering eutrophication, and its biogeochemical behavior has attracted much attention. This study investigated the distribution of phosphorus fractions and the adsorption-desorption characteristic in the soils of wetlands converted from paddy fields with a restoration duration of 1, 2, 3, 5, 13, or 19 years. The results demonstrated the content of total phosphorus (TP) first increased, which was then reversed until the process stabilized after 5 restoration years. Labile inorganic phosphorus (L-Pi), labile organic phosphorus (L-Po), iron-aluminum–bound phosphorus (Fe.Al-P), and humic phosphorus (Hu-P) peaked at 1–3 restoration years, respectively, while moderately labile organic phosphorus (Ml-Po), calcium-magnesium–bound phosphorus (Ca.Mg-P), and residual phosphorus (Re-P) decreased within 0–5 restoration years. During the 5th to 19th restoration years, the contents of all phosphorus fractions stabilized within a minor fluctuating range. Redundancy analysis (RDA) results indicated that total nitrogen (TN) and soil organic matter (SOM) are the important environmental factors controlling redistribution of phosphorus fractions. The capability of restored wetlands to retain phosphorus increased first and then decreased with the extension of the restoration duration. Path analysis (PA) results demonstrated that pH, TN, and Fe are the primary factors for the capacity of soil to retain phosphorus, followed by SOM, Mn, and electrical conductivity(EC). Fe.Al-P and Hu-P had a higher release risk with approximate amounts of 197.25–337.25 and 113.28–185.72 mg/kg during the first stage of restoration, which needs to be focused.

26470. 题目: Dissolution and aggregation kinetics of zero valent copper nanoparticles in (simulated) natural surface waters: Simultaneous effects of pH, NOM and ionic strength
文章编号: N19040907
期刊: Chemosphere
作者: Daniel Arenas-Lago, Fazel Abdolahpur Monikh, Martina G. Vijver, Willie J.G.M. Peijnenburg
更新时间: 2019-04-09
摘要: The combined effects of pH, dissolved organic carbon (DOC) and Ca²⁺/Mg²⁺ on the dissolution and aggregation kinetics of zero valent copper engineered nanoparticles (Cu⁰ ENPs) were investigated. The dissolution and aggregation of the particles were studied in (a) synthetic aqueous media, similar in chemistry to natural surface waters, and (b) natural surface waters samples, for up to 32 or 24 h. The DOC stabilized the particles and prevented aggregation, and thus increased the available surface area. The higher available surface area in turn accelerated the dissolution of the particles. The presence of Ca²⁺/Mg²⁺, however, changed the aggregation and the dissolution of the DOC-stabilized particles. The influence of Ca²⁺/Mg²⁺ on DOC-stabilized particles was different at different pH's. In the absence of DOC, 10 mM of Ca²⁺/Mg²⁺ induced charge reversal on the particles and caused particle stability against aggregation. This subsequently increased particles dissolution. The results obtained with regard to dissolution and aggregation of the particles in natural surface waters were compared with those determined for the synthetic waters. This comparison showed that the behavior of the particles in the natural surface waters was mostly similar to the behavior determined for media at pH 9. Overall, the current study provides some novel insights into the simultaneous effects of physicochemical parameters of water on particle stability against aggregation and dissolution, and provides data about how the processes of aggregation and dissolution of Cu⁰ ENPs interact and jointly determine the overall particle fate.
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26471. 题目: Promoting waste activated sludge reduction by linear alkylbenzene sulfonates: surfactant dose control extracellular polymeric substances solubilization and microbial community succession
文章编号: N19040906
期刊: Journal of Hazardous Materials
作者: Yun Zhou, Zhiqiang Zhang, Lei Zhang, Shengnan Xu, Bing Guo, Yang Liu, Siqing Xia
更新时间: 2019-04-09
摘要: Short-time aerobic digestion (STAD) was proved to promote the reduction of waste activated sludge (WAS). This study systematically disclosed the influential characteristics and mechanisms of linear alkylbenzene sulfonates (LAS) dosage on the reduction of WAS in STAD system. Flow cytometer (FC) combined with SYTOX Green (SG) dye was used to differentiate extracellular polymeric substances (EPS) release and cell lysis of WAS during STAD process. LAS lower than 0.10 g/g total suspended solids (TSS) brought about EPS solubilization and the decrease of sludge floc size, and the accumulated soluble microbial products (SMP) could be biodegraded by heterotrophs. Moreover, the activity of microorganisms (denoted as specific oxygen uptake rate (SOUR)) and proportion of bacteria functional for LAS and SMP biodegradation dramatically increased, leading to a high LAS biodegradation rate (k_LAS) and increased WAS biodegradation rate (k_{COD, WAS}). Even more LAS (> 0.10 g/g TSS) caused cell lysis, leading to the decreased k_TCOD and k_LAS, and therefore inhibit the reduction of WAS. High WAS reduction and LAS biodegradation rate were achieved at the LAS dosage of 0.10 g/g TSS in STAD system. This study lays the foundation for improving WAS reduction by optimizing surfactant dose in STAD system.
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26472. 题目: Erodibility assessment of compacted biochar amended soil for geo-environmental applications
文章编号: N19040905
期刊: Science of The Total Environment
作者: Himanshu Kumar, Suriya Prakash Ganesan, Sanandam Bordoloi, S. Sreedeep, Peng Lin, Guoxiong Mei, Ankit Garg, Ajit K. Sarmah
更新时间: 2019-04-09
摘要: Biochar amended soil (BAS) has been explored as a cover material for geo-environmental applications such as landfill cover due to its vegetation potential. Soil erosion in these infrastructures can progressively lead to failure and hamper the workability of the system. BAS is compacted for geo-environmental applications, unlike agricultural soil, which are loose in nature. Furthermore, the love-hate relationship of biochar with water can potentially affect the functioning of compacted cover system. Thus, the performance of compacted BAS in the context of erosion potential is not well understood. The major objective of this technical note was to explore the erosion potential of compacted BAS sourced from four distinct biochars. Biochar were produced in-house and mixed with soil at 5% and 10% by weight. In total, 81 pinhole erosion tests were performed to gauge the erosion rate of bare soil and BAS at three different compaction states at same compaction energy. It was revealed that the erosion rate decreased with gradual increment in water content for BAS, which was mainly attributed to the change of particle orientation from flocculated to dispersed along the compaction curve. Addition of biochar to soil resulted in decrease of erosion along the dry state whereas the opposite was observed for wet state. This was attributed to the surface functional groups as well as particle gradation of biochar. Erodibility coefficient and critical shear stress plot of soil and BAS revealed that addition of biochar had minimal effect on erosion of compacted silty sand.
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26473. 题目: Discriminating sources and preservation of organic matter in surface sediments from five Antarctic lakes in the Fildes Peninsula (King George Island) by lipid biomarkers and compound-specific isotopic analysis
文章编号: N19040904
期刊: Science of The Total Environment
作者: Daniel Carrizo, Laura Sánchez-García, Rodrigo Javier Menes, Felipe García-Rodríguez
更新时间: 2019-04-09
摘要: Lakes are important paleoenvironmental archives retaining abundant information due to their typical high sedimentation rates and susceptibility to environmental changes. Here, we scrutinize the organic matter (OM) composition, origin and preservation state in surface sediments from five lakes in a remote, warming-sensitive, and poorly explored region partially covered by the retreating Collins Glacier in King George Island (Antarctica), the Fildes Peninsula. Lipid biomarkers of terrestrial origin (i.e. high-molecular weight n-alkanes, n-alkanoic acids, and n-alkanols; β-sitosterol, campesterol, and stigmasterol) were detected in the five Fildes Lakes, with the smallest basin (i.e., Meltwater) showing a particularly strong moss imprint. Aquatic source indicators such as low C/N and terrestrial over aquatic ratios (TAR), or less negative δ¹³C values were preferentially found in the mid-sized lakes (i.e., Drake and Ionospheric). Sedimentary carbon in the larger lakes (i.e., Uruguay and Kitezh) displayed a largely biogenic origin (i.e., values of carbon preference index, CPI, ≫1), whereas the three lakes close to Collins Glacier (i.e., Drake, Meltwater, and Ionospheric) showed certain contribution from petrogenic sources (CPI ~ 1). The results suggest that the geochemical signature of the surface sediments in the five Fildes lakes is determined by factors such as the distance to the retreating Collins Glacier, the proximity to the coast, or the lake depth. This study illustrates the forensic interest of combining lipid biomarkers, compound-specific isotopic analysis, and bulk geochemistry to reconstruct paleoenvironments and study climate-sensitive regions.
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26474. 题目: Impact of mercury speciation on its removal from water by activated carbon and organoclay
文章编号: N19040903
期刊: Water Research
作者: Ke Gai, Astrid Avellan, Thomas P. Hoelen, Francisco Lopez-Linares, Evan S. Hatakeyama, Gregory V. Lowry
更新时间: 2019-04-09
摘要: Mercury (Hg) speciation can affect its removal efficiency by adsorbents. This study assessed the removal of dissolved inorganic Hg(II) species (Hg(II)*), β-HgS nanoparticles (HgS NP), and Hg complexed with dissolved organic matter (Hg-DOM) by three sorbents: activated carbon (AC), sulfur-impregnated activated carbon (SAC), and organoclay (OC). The effect of ionic composition, solution ionic strength, and natural organic matter (NOM) concentration on the removal of each Hg species was also evaluated. The three adsorbents were all effective in removing Hg(II)*, Hg-DOM, and HgS NPs. Increasing ionic strength decreased the removal of Hg(II)* species due to the formation of ionic Hg species with lower affinity for the sorbents. Added NOM decreased the removal of Hg(II)* and HgS NPs by all sorbents with the OC sorbent being most susceptible to NOM fouling. On a surface area-normalized basis, the OC removed all types of Hg species better than the AC and SAC samples. Moreover, adsorbed Hg-DOM transformed to a β-HgS phase on the OC, but not for AC and SAC. These studies indicate that both Hg speciation and the water quality parameters need to be considered when designing sorbent-based emission controls to meet Hg removal targets.
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26475. 题目: Limits of our knowledge, part 2: Selected frontiers in marine organic biogeochemistry
文章编号: N19040902
期刊: Marine Chemistry
作者: Stuart G. Wakeham, Cindy Lee
更新时间: 2019-04-09
摘要: The advent of new sampling tools, analytical methods, and data handling capabilities that have been applied to marine chemistry since the 1970s along with coordinated, international and interdisciplinary research programs has led to explosive growth of marine organic biogeochemistry. Here we briefly summarize the history of stepwise growth as illustrated by community-wide workshop reports and symposia, highlighting evolving recommendations for future research put forth in those reports. Following that, we present examples of four frontiers that have been explored recently, focusing as much as possible at the molecular level and on marine water columns: (i) how analytical advances and informatics tools provide new insight into the chemical nature and cycling of dissolved organic matter; (ii) how evolving studies of suspended and sinking particles play an important role in understanding ocean biogeochemistry; (iii) the new symbiosis between marine microbiology, analytical chemistry and organic geochemistry as illustrated by the archaea, their habitats, lipid biomarkers, and influence on geochemical cycles; and (iv) how advances in compound-specific measurements of carbon, nitrogen, hydrogen, and sulfur isotopes shed new light on sources and behavior of marine organic matter. We cite selected recent (primarily the past two decades) research examples as a basis for further reading and to project into the future some aspects of these research areas that could be further developed. Throughout, we highlight how new analytical and sampling methods allowed these fields to progress.

26476. 题目: Distribution and speciation of copper and its relationship with FDOM in the East China Sea
文章编号: N19040901
期刊: Marine Chemistry
作者: Kuo Hong Wong, Hajime Obata, Taejin Kim, Yohei Wakuta, Shigenobu Takeda
更新时间: 2019-04-09
摘要: Total dissolved Cu concentrations, concentrations and conditional stability constants of Cu-binding organic ligands, and the intensities of fluorescent dissolved organic matter (FDOM) components in seawater were determined in the East China Sea. Concentrations of organic ligands were determined using CLE-AdCSV with a 5 μM SA detection window. Total dissolved Cu concentrations ranged from 0.59 nM to 4.65 nM and were particularly high in surface waters with low salinity due to influences of the Changjiang Diluted Water. Concentrations of the stronger ligand (L₁) were between 0.65 and 6.92 nM and its distribution closely followed that of dissolved Cu. Four FDOM components were detected in surface waters, including two humic-like and two protein-like components. L₁ concentrations exhibited similar distribution patterns to the intensities of all four FDOM components. The concentrations of the weaker ligands (L₂) ranged from 2.86 nM to 31 nM, with the highest concentrations detected in the surface waters of stations unaffected by the Kuroshio Current. We found the buffering ability of Cu-binding organic ligands in the East China Sea to be sufficient for responding to atmospheric and anthropogenic Cu inputs and keeping the free cupric ion concentrations relatively constant.

26477. 题目: Effects of plant functional group removal on structure and function of soil communities across contrasting ecosystems
文章编号: N19040809
期刊: Ecology Letters
作者: Nicolas Fanin, Paul Kardol, Mark Farrell, Anne Kempel, Marcel Ciobanu, Marie‐Charlotte Nilsson, Michael J. Gundale, David A. Wardle
更新时间: 2019-04-08
摘要: Loss of plant diversity has an impact on ecosystems worldwide, but we lack a mechanistic understanding of how this loss may influence below‐ground biota and ecosystem functions across contrasting ecosystems in the long term. We used the longest running biodiversity manipulation experiment across contrasting ecosystems in existence to explore the below‐ground consequences of 19 years of plant functional group removals for each of 30 contrasting forested lake islands in northern Sweden. We found that, against expectations, the effects of plant removals on the communities of key groups of soil organisms (bacteria, fungi and nematodes), and organic matter quality and soil ecosystem functioning (decomposition and microbial activity) were relatively similar among islands that varied greatly in productivity and soil fertility. This highlights that, in contrast to what has been shown for plant productivity, plant biodiversity loss effects on below‐ground functions can be relatively insensitive to environmental context or variation among widely contrasting ecosystems.

26478. 题目: “-Omics” workflow for paleolimnological and geological archives: A review
文章编号: N19040808
期刊: Science of The Total Environment
作者: Madison Bell, Jules M. Blais
更新时间: 2019-04-08
摘要: “-Omics” is a powerful screening method with applications in molecular biology, toxicology, wildlife biology, natural product discovery, and many other fields. Genomics, proteomics, metabolomics, and lipidomics are common examples included under the “-omics” umbrella. This screening method uses combinations of untargeted, semi-targeted, and targeted analyses paired with data mining to facilitate researchers' understanding of the genome, proteins, and small organic molecules in biological systems. Recently, however, the use of “-omics” has expanded into the fields of geology, specifically petrology, and paleolimnology. Specifically, untargeted analyses stand to transform these fields as petroleomics, and sediment-“omics” become more prevalent. “-Omics” facilitates the visualization of small molecule profiles from environmental matrices (i.e. oil and sediment). Small molecule profiles can provide improved understanding of small molecules distributions throughout the environment, and how those compositions can change depending on conditions (i.e. climate change, weathering, etc.). “-Omics” also facilities discovery of next-generation biomarkers that can be used for oil source identification and as proxies for reconstructing past environmental changes. Untargeted analyses paired with data mining and multivariate statistical analyses represents a powerful suite of tools for hypothesis generation, and new method development for environmental reconstructions. Here we present an introduction to “-omics” methodology, technical terms, and examples of applications to paleolimnology and petrology. The purpose of this review is to highlight the important considerations at each step in the “-omics” workflow to produce high quality and statistically powerful data for petrological and paleolimnological applications.
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26479. 题目: Sorption mechanisms of lead on silicon-rich biochar in aqueous solution: Spectroscopic investigation
文章编号: N19040807
期刊: Science of The Total Environment
作者: Jianhong Li, Lirong Zheng, Shan-Li Wang, Zhipeng Wu, Weidong Wu, Nabeel Khan Niazi, Sabry M. Shaheen, Jörg Rinklebe, Nanthi Bolan, Yong Sik Ok, Hailong Wang
更新时间: 2019-04-08
摘要: Unraveling sorption mechanisms of lead (Pb) to silicon (Si)-rich biochar at molecular scale in aqueous solution are essential for the effective application of the biochars to the remediation of Pb and other metal(loid)s pollution in the environment. Thus, this study investigated the contributions of phytoliths and other compounds to the Pb sorption on Si-rich coconut fiber biochar (CFB500) and the corresponding sorption mechanisms using spectroscopic techniques, including the micro-X-ray fluorescence (μ-XRF), X-ray absorption fine structure (XAFS), scanning electron microscopy combined with energy dispersive X-ray spectroscopy, and X-ray diffraction. The μ-XRF and XAFS results showed that K, Ca, Cu, Mn, and Fe were released and significantly related to Pb in Pb-loaded CFB500; four major Pb species were formed with similar structures to lead carboxylate (e.g., Pb(C₂H₃O₂)₂), Pb₃(PO₄)₂, PbSiO₃, and PbCO₃. On phytoliths in CFB500, Pb²⁺ ions were mainly sorbed on the sites of silicate with a structure similar to PbSiO₃. The contribution of binding sites for Pb²⁺ sorption was ascribed to the outer-wall of carbon skeleton of CFB500, which was stronger than that provided by the mineral oxide aggregate and phytoliths on CFB500. Organic carbon functional groups, inorganic carbonates, silicates and phosphates on CFB500 mostly dominated the sorption sites for Pb²⁺. Our results suggest that CFB500 was a promising material for the remediation of Pb-contaminated aqueous environments (e.g., wastewater).
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26480. 题目: Mobilization of mercury species under dynamic laboratory redox conditions in a contaminated floodplain soil as affected by biochar and sugar beet factory lime
文章编号: N19040806
期刊: Science of The Total Environment
作者: Felix Beckers, Sibylle Mothes, Jens Abrigata, Jiating Zhao, Yuxi Gao, Jörg Rinklebe
更新时间: 2019-04-08
摘要: Mercury and its species are toxic and therefore strategies to immobilize them or to impede the formation of bioaccumulative MeHg are a hot topic of ongoing research. Biochar (BC) and sugar beet factory lime (SBFL) are suggested to have the potential to meet these goals. However, their ability to restrain the mobilization of total Hg (Hg_t), methylmercury (MeHg), and ethylmercury (EtHg) or the formation of MeHg and EtHg has not been examined to date. Moreover, the effect of systematically altered redox conditions on the release dynamics of Hg_t, MeHg, and EtHg in a contaminated floodplain soil as affected by these soil amendments has not been studied. Therefore, we investigated the impact of pre-defined redox conditions on the release dynamics of Hg_t, MeHg, and EtHg in a contaminated floodplain soil (CS) and the soil amended with either BC (CS+BC) or SBFL (CS+SBFL).The mobilization of Hg_t, MeHg, and EtHg was generally higher at low redox potential (E_H) and decreased with increasing E_H, irrespective of soil treatment. Both BC and SBFL diminished the release of Hg_t from soil but not the methylation and ethylation of Hg. In CS+SBFL approximately half of Hg_t was found in solution compared to CS. However, higher methylation efficiency (MeHg/Hg_t ratio) was found in CS+SBFL counterbalancing this benefit. Abundances of specific phospholipid fatty acids suggest the presence of sulfate-reducing bacteria, which are considered as primary Hg methylators. The results indicate that both BC and SBFL have the potential to curtail the release of Hg_t from inundated soils, while SBFL was more efficient. However, these amendments had no marked effect on the MeHg and EtHg concentrations. Therefore, further research should be conducted to identify soil additives that are capable to reduce the release and formation of these Hg species.
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