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25601. 题目: Consecutive reduction of Cr(VI) by Fe(II) formed through photo-reaction of iron-dissolved organic matter originated from biochar
文章编号: N19071504
期刊: Environmental Pollution
作者: Hye-Bin Kim, Jong-Gook Kim, Seon-Hee Kim, Eilhann E. Kwon, Kitae Baek
更新时间: 2019-07-15
摘要: Employing biochar for environmental remediation has been widely practiced. Nonetheless, the reduction mechanisms of hexavalent chromium (Cr(VI)) in the presence of biochar have not been fully elucidated (i.e., direct or indirect reduction of Cr(VI) by biochar). In particular, the effect of light on Cr(VI) reduction by biochar was rarely reported. Thus, to clarify the reduction mechanisms of Cr(VI) by biochar at the fundamental level, this study laid great emphasis on the photo-induced reduction of Cr(VI) in the application of biochar. Biochar releases dissolved organic matter (DOM), the DOM can extract Fe(III) from soil by complexation, and the complexes can be photo-reacted under the light. In these respects, Fe(II) formed by the photo-induced reaction of DOM-Fe(III) was particularly evaluated in this study. To evaluate that, three biomass samples (rice straw, granular sludge from an up-flow anaerobic sludge blanket, and spent coffee ground) were torrefied to biochar. To circumvent the adsorption of Cr(VI) onto biochar, biochar extractives (served as a source for DOM) and Fe(III) solution were tested with/without UV light to prove Fe(II) formation. This study experimentally proved that the more Fe(II) under the UV radiation was formed in the co-existence with biochar extractives and Fe(III). All experimental data from three biochar samples were indeed very similar. Cr(VI) reduction by Fe(II) from GB, RB, and CB reached up to 96, 79, and 100%, respectively. The different reduction efficiency signified that the low molecular weight of organic acids, such as oxalate, were more sensitive to the UV light, thereby resulting in the enhanced Fe(II) formation. Such Fe(II) formation subsequently led to the high reduction efficiency of Cr(VI).
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25602. 题目: Marsh edge erosion and associated carbon dynamics in coastal Louisiana: A proxy for future wetland-dominated coastlines world-wide
文章编号: N19071503
期刊: Estuarine, Coastal and Shelf Science
作者: Yadav Sapkota, John R. White
更新时间: 2019-07-15
摘要: Coastal wetland loss through marsh edge erosion is a serious problem in Louisiana. The majority of studies on coastal land loss use aerial and satellite photographic analysis while field and site-specific measurements are limited. The aim of this study was to spatially and temporally measure coastal marsh edge erosion and investigate factors responsible for differences in erosion including shoreline orientation, soil physio-chemical properties, wind speed and duration. A total of 33 transects across six island sites in northern Barataria Basin, Louisiana were established. Transects on shorelines facing different compass directions were measured for erosion for up to 2 years. Soils were analyzed for physiochemical properties including bulk density, organic matter, total carbon, nitrogen, and phosphorus. Bathymetric surveys were conducted to determine the extent of the erosive bay bottom profile. In addition, ¹⁴C dating of the basal organic matter (1.5–1.6 m) was conducted. Erosion rates ranged from 49.27 to 324.85 cm y-1 with a mean value of 141.69 ± 22.45 cm y⁻¹. As expected, erosion rates were significantly different (p < 0.001) between protected and unprotected sites. The erosion rate was not correlated with wind speed (r = -0.07), weakly correlated with compass direction of shoreline (r = 0.25) and water level (r = 0.25) but strongly correlated with duration of wind (r = 0.60). Erosion rate was negatively correlated (r = -0.45) with bulk density and positively correlated with organic matter content (r = 0.42) of the top 40 cm of the soil. Over time, the marsh is eroded down to a depth of 1.5 m, which correlates to annual loss of 1.82 ± 0.29 m³ volume of marsh per meter shoreline length including a loss of organic matter (141.5 ± 22.55 kg m⁻¹) and carbon (63.32 ± 10.09 kg m⁻¹) previously preserved for up to 850 years. As a consequence, annual CO₂ emissions for Barataria Basin were estimated to be 1.56 ± 0.26 million tCO₂e y⁻¹. Results can inform coastal managers as to the most vulnerable marshes to target restoration efforts. Due to high relative sea level rise in coastal Louisiana, these results can also be used to inform the world's stable coastlines on the relative vulnerability of their coastal marshes in the near future, due to projected eustatic sea level. Consequently, the eroding coastlines across the globe may be a significant source of CO₂ emissions in near future, as millennial age stored soil carbon is released in a relatively short time, potentially overwhelming human efforts to slow rising atmospheric CO₂ levels.
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25603. 题目: Greenhouse gas emissions from a rice-rice-green manure cropping system in South China
文章编号: N19071502
期刊: Geoderma
作者: Abdulkareem Raheem, Jun Zhang, Jing Huang, Yu Jiang, Mohammad Abubakar Siddik, Aixing Deng, Jusheng Gao, Weijian Zhang
更新时间: 2019-07-15
摘要: Green manure crops play an important role in reducing chemical fertilizer applications while enhancing soil fertility. However, the effects of winter-planted green manure crops on rice paddy greenhouse gas (GHG) emissions are poorly understood. Based on a 35 years experiment, we analyzed the impacts of a rice-rice-green manure cropping system on rice yield and GHG emissions during both rice and winter-green manure seasons. Our experiment consisted of four treatments: ryegrass-rice-rice (Ry-R-R), milkvetch rice-rice (Mv-R-R), rapeseed-rice-rice (Rp-R-R) and fallow-rice-rice (Fa-R-R), arranged in a completely randomized design. Incorporation of winter-planted green manure had more impacts on yield and CH₄ emission in the early rice season than in the late rice season. Compared to the Fa-R-R, the Mv-R-R, Rp-R-R, and Ry-R-R systems increased annual yield by 15.4%, 11.8%, and 6.1%, respectively. However, Ry-R-R and Rp-R-R significantly increased annual CH₄ emissions by 116.73% and 52.45%, respectively, while Mv-R-R reduced CH₄ emissions by 16.3%, compared to Fa-R-R. The CH₄ emissions showed significant positive correlations with dissolved organic carbon, as well as the biomass and C/N ratio of the incorporated green manure plant materials. Although green manuring reduced N₂O emissions in both winter and rice seasons, there was no significant difference in annual cumulative N₂O emissions among the treatments. Ry-R-R and Rp-R-R increased annual yield-scaled GWP by 102.6% and 34.8%, respectively, while Mv-R-R was 27.8% lower, compared to the Fa-R-R. Our results suggest that Mv-R-R is the best choice of cropping system for yield sustainability and eco-friendly rice production over the long-term.

25604. 题目: Synthesis of novel biochar from waste plant litter biomass for the removal of Arsenic (III and V) from aqueous solution: A mechanism characterization, kinetics and thermodynamics
文章编号: N19071501
期刊: Journal of Environmental Management
作者: Lata Verma, Jiwan Singh
更新时间: 2019-07-15
摘要: The present study is focusing on utilization of a new feedstock material for the preparation of biochar. The dry waste leaves litter of Tectona and Lagerstroemia speciosa was used for synthesizing the biochar at 800 °C for 1 h in muffle furnace represents as TB 800 and LB 800 and then used for the removal of As(III) and As(V) from aqueous solution. The prepared biochar materials had a crystalline structure and was characterized by using Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX), Brunaur emmit teller (BET), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Zeta potential, particle size and X-ray photoelectron spectroscopy (XPS). In regeneration study it was observed that prepared biochar material could be used up to four times with good removal percentage of Arsenic (III and V). The experimental data fitted well by Langmuir model for As(V) removal using TB 800 and LB 800, Freundlich model for As(III) removal by LB 800 and Temkin model for As(III) removal by TB 800. Pseudo-second-order kinetics was followed and best fitted with the obtained data of As(III) and (V) removal. Thermodynamics study revealed that the process of adsorption was endothermic for the removal of As(III) and exothermic for the adsorption of As(V) using TB 800 and LB 800. The adsorption capacity obtained for the removal of As(III) was 666.7 μg/g and 454.54 μg/g for TB 800 and LB 800, respectively and adsorption capacity for As(V) was 1250 μg/g for TB 800 and 714.28 μg/g was attained by LB 800.
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25605. 题目: Raman Tweezers for Small Microplastics and Nanoplastics Identification in Seawater
文章编号: N19071407
期刊: Environmental Science & Technology
作者: Raymond Gillibert, Gireeshkumar Balakrishnan, Quentin Deshoules, Morgan Tardivel, Alessandro Magazzù, Maria Grazia Donato, Onofrio M. Maragò, Marc Lamy de La Chapelle, Florent Colas, Fabienne Lagarde, Pietro Giuseppe Gucciardi
更新时间: 2019-07-14
摘要: Our understanding of the fate and distribution of micro- and nano- plastics in the marine environment is limited by the intrinsic difficulties of the techniques currently used for the detection, quantification, and chemical identification of small particles in liquid (light scattering, vibrational spectroscopies, and optical and electron microscopies). Here we introduce Raman Tweezers (RTs), namely optical tweezers combined with Raman spectroscopy, as an analytical tool for the study of micro- and nanoplastics in seawater. We show optical trapping and chemical identification of sub-20 μm plastics, down to the 50 nm range. Analysis at the single particle level allows us to unambiguously discriminate plastics from organic matter and mineral sediments, overcoming the capacities of standard Raman spectroscopy in liquid, intrinsically limited to ensemble measurements. Being a microscopy technique, RTs also permits one to assess the size and shapes of particles (beads, fragments, and fibers), with spatial resolution only limited by diffraction. Applications are shown on both model particles and naturally aged environmental samples, made of common plastic pollutants, including polyethylene, polypropylene, nylon, and polystyrene, also in the presence of a thin eco-corona. Coupled to suitable extraction and concentration protocols, RTs have the potential to strongly impact future research on micro and nanoplastics environmental pollution, and enable the understanding of the fragmentation processes on a multiscale level of aged polymers.

25606. 题目: Effects of different scrap iron as anode in Fe-C micro-electrolysis system for textile wastewater degradation
文章编号: N19071406
期刊: Environmental Science and Pollution Research
作者: Zhenhua Sun, Zhihua Xu, Yuwei Zhou, Daofang Zhang, Weifang Chen
更新时间: 2019-07-14
摘要: The degradation of organic contaminants in actual textile wastewater was carried out by iron carbon (Fe-C) micro-electrolysis. Different Fe-C micro-electrolysis systems (SIPA and SISA) were established by using scrap iron particle (SIP) and scrap iron shaving (SIS) as anode materials. The optimal condition of both systems was obtained at the initial pH of 3.0, dosage of 30 g/L and Fe/C mass ratio of 1:1. Commercial spherical Fe-C micro-electrolysis material (SFC) was used for comparison under the same condition. The results indicated that total organic carbon (TOC) and chroma removal efficiencies of SIPA and SISA were superior to that of SFC. Total iron concentration in solution and XRD analysis of electrode materials revealed that the former showed relatively high iron corrosion intensity and the physicochemical properties of scrap iron indeed affected the treatment capability. The UV-vis and 3DEEM analysis suggested that the pollutants degradation was mainly attributed to the combination of reduction and oxidation. Furthermore, the potential degradation pathways of actual textile wastewater were illustrated through the GC-MS analysis. Massive dyes, aliphatic acids, and textile auxiliaries were effectively degraded, and the SIPA and SISA exhibited higher performance on the degradation of benzene ring and dechlorination than that by SFC. In addition, SIPA and SISA exhibited high stability and excellent reusability at low cost.

25607. 题目: Deep soil inventories reveal that impacts of cover crops and compost on soil carbon sequestration differ in surface and sub‐surface soils
文章编号: N19071405
期刊: Global Change Biology
作者: N.E. Tautges, J. Chiartas, A.C.M. Gaudin, A.T. O'Geen, I. Herrera, K. M.Scow
更新时间: 2019-07-14
摘要: Increasing soil organic carbon (SOC) via organic inputs is a key strategy for increasing long‐term soil C storage and improving the climate change mitigation and adaptation potential of agricultural systems. A long‐term trial in California's Mediterranean climate revealed impacts of management on SOC in maize‐tomato and wheat–fallow cropping systems. SOC was measured at the initiation of the experiment and at year 19, at five depth increments down to 2 m, taking into account changes in bulk density. Across the entire 2 m profile, SOC in the wheat–fallow systems did not change with the addition of N fertilizer, winter cover crops (WCC), or irrigation alone and decreased by 5.6% with no inputs. There was some evidence of soil C gains at depth with both N fertilizer and irrigation, though high variation precluded detection of significant changes. In maize‒tomato rotations, SOC increased by 12.6% (21.8 Mg C ha^‐1) with both WCC and composted poultry manure inputs, across the 2‐m profile. The addition of WCC to a conventionally managed system increased SOC stocks by 3.5% (1.44 Mg C ha^‐1) in the 0 to 30 cm layer, but decreased by 10.8% (14.86 Mg C ha^‐1) in the 30 to 200 cm layer, resulting in overall losses of 13.4 Mg C ha^‐1. If we only measured soil C in the top 30 cm, we would have assumed an increase in total soil C increased with WCC alone, whereas in reality significant losses in SOC occurred when considering the 2‐m soil profile. Ignoring the subsoil carbon dynamics in deeper layers of soil fails to recognize potential opportunities for soil C sequestration, and may lead to false conclusions about the impact of management practices on C sequestration.

25608. 题目: Adsorption and co-adsorption of tetracycline and doxycycline by one-step synthesized iron loaded sludge biochar
文章编号: N19071404
期刊: Chemosphere
作者: Jia Wei, Yitao Liu, Jun Li, Yuhan Zhu, Hui Yu, Yongzhen Peng
更新时间: 2019-07-14
摘要: Application of biochar as an adsorbent for wastewater treatment has obtained a tremendous research interest owning to their low cost and surface functionality. In this research, an iron loaded sludge biochar was successfully prepared through a simple and economical one-step modification hydrothermal method. The iron loaded sludge biochar possesses large amounts of surface organic functional groups (such as hydroxy, carboxyl and aromatic ring, etc.), smaller particle size (about 10 nm) as well as relative higher surface area (82.780 m² g⁻¹) than of the pristine one. The selective removal of two kinds of antibiotics by the prepared products was demonstrated. Experimental data was fitted to isotherm and kinetic models, and thermodynamic parameters were also calculated. In the single antibiotic system, the maximum adsorption amount of tetracycline (TC) and doxycycline (DOX) could reach 104.86 and 128.98 mg g⁻¹ at 293.15 K, respectively. In the binary antibiotics system, there was an antagonistic effect between TC and DOX. Furthermore, the adsorption of TC was much more inhibited than that of DOX owning to its deferent steric hindrance of molecular structure.
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25609. 题目: Interactions between natural organic matter (NOM) and the cationic dye toluidine blue at varying pHs and ionic strengths: Effects of NOM charges and Donnan gel potentials
文章编号: N19071403
期刊: Chemosphere
作者: Xiaoyun Xie, Hongguang Guo, Mingquan Yan, Gregory Korshin
更新时间: 2019-07-14
摘要: This study examined effects of charges of molecules of natural organic matter (NOM) on its interactions with organic cations represented by toluidine blue (TB). NOM was exemplified in this study by Suwannee River (SR) and South Platte (SP) NOM. TB/NOM interactions were probed in the range of pH 3 to 11, DOC concentrations 0–10.6 mg L⁻¹ and ionic strengths 0.001–0.1 mol L⁻¹. Changes of TB absorbance at indicative wavelengths of 640 and 550 nm located in the characteristic absorbance band of TB and their ratio R_640/550 were used to quantify TB/NOM binding and the formation of TB dimers and possibly higher order aggregates in the Donnan volume of NOM molecules. These effects were interpreted based on the modeling of NOM charges and their Donnan gel potentials (ψ_D). The spectroscopic and modeling data showed that TB/NOM binding can be quantified via a complexation model that reflects the extent of electrostatic attraction between TB cations and anionic NOM molecules. The dependence of the apparent formation constant vs. ionic strength was shown to be qualitatively correlated with the ψ_D potentials of NOM molecules.

25610. 题目: Potential use of biochar, compost and iron grit associated with Trifolium repens to stabilize Pb and As on a multi-contaminated technosol
文章编号: N19071402
期刊: Ecotoxicology and Environmental Safety
作者: R. Nandillon, O. Lahwegue, F. Miard, M. Lebrun, M. Gaillard, S. Sabatier, F. Battaglia-Brunet, D. Morabito, S. Bourgerie
更新时间: 2019-07-14
摘要: Vegetation cover can be used in the phytomanagement of polluted areas by adding value to abandoned sites and reducing the dispersion of pollutants by erosion. Appropriate amendments, that allow both efficient plant growth and the immobilization of contaminants in the soil must be chosen in order to optimize the efficiency of this process. We used a mining technosol mainly contaminated by arsenic (1068 mg kg⁻¹) and lead (23387 mg kg⁻¹) to study the effect of three amendments (biochar, compost and iron grit) on (i) physico-chemical properties of the soil and soil pore water, (ii) metal(loid) mobility, bioavailability and bioaccessibility (CaCl₂ and Simple Bioaccessibility Extraction Test (SBET)), and (iii) the capability of Trifolium repens to germinate and grow. All the amendments used increased the pH and electrical conductivity of the SPW, resulting in a 90% decrease in the concentration of lead in the soil pore water (SPW). We also demonstrated a decrease in Pb phytoavailability. The amendments allowed the establishment of a plant cover, although the addition of iron grit alone did not allow any clover germination. For the Pontgibaud technosol, the combination of the three amendments resulted in a significant decrease in As and Pb concentrations in clover tissues, mainly in the aerial organs. The amendments also made it possible for some of them to halve the phytoavailable fraction of arsenic. However, for compost, both the As concentrations in the SPW, and the bioavailable fraction of As increased. All the amendments used had contrasting effects on the bioaccessible fractions of metal(loid)s. The most efficient amendment combination was the addition of 5% biochar and 5% compost.

25611. 题目: A further inquiry into co-pyrolysis of straws with manures for heavy metal immobilization in manure-derived biochars
文章编号: N19071401
期刊: Journal of Hazardous Materials
作者: Yonggang Xu, Fangjie Qi, Tianxia Bai, Yubo Yan, Congcong Wu, Zirun An, Shan Luo, Zhong Huang, Peng Xie
更新时间: 2019-07-14
摘要: Co-pyrolysis of straws with manures has been found effective to mitigate heavy metal risks in manure-derived biochars. This study further investigated co-pyrolysis strategy on the levels, species and risks of metals (Cu, Zn, Cr, Ni, Pb, and Cd) carried by manure-based biochars through co-pyrolyzing swine manure (SM) and corn straw (CS) with different mixture ratios (1:0, 0:1, 3:1, 1:1, and 1:3, w/w) at 300 ℃, 500 ℃ and 700 ℃. The total heavy metals in SM biochars were significantly reduced by CS addition except when SM/CS ratio was 3:1 at 300 ℃. Notably, CS addition increased stable Ni, Zn, Cu, Pb and Cd, but simultaneously mobilized part of Ni, Zn, Cu and Pb in SM biochars, especially at higher CS ratio and higher temperature. Co-pyrolysis converted less stable Cd to more stable Cd at all pyrolysis conditions, with higher CS ratio and higher temperature more effective. Overall, higher temperature (700℃) and higher addition ratio of CS (SM/CS 1:3) were more favorable for mitigating the potential ecological index of biochar-bearing Cd, Cu and Zn, the dominating risky contributor to SM biochars, hence more effective to mitigate the overall environmental risks of heavy metals in the derived SM biochars.
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25612. 题目: Bacterial Community Structure Recovery in Reclaimed Coal Mined Soil under Two Vegetative Regimes
文章编号: N19071308
期刊: Journal of Environment Quality
作者: John P. Brooks, Ardeshir Adeli, Renotta K. Smith, Rebecca McGrew, David J. Lang, John J. Read
更新时间: 2019-07-13
摘要: Coal mining can be deleterious to the soil physical and chemical makeup, but also to the soil microbial community. Effectively, the removal of nearly all organic matter from the upper soil horizons reduces the effectiveness of any soil to support vegetation, and up until recently, microbial community parameters were not considered in the successful reclamation of overburden. Thus, our study proposes to measure the uncultivated bacterial community using 16S ribosomal RNA (rRNA) high-throughput sequencing in a chronosequence of reclaimed overburden in Mississippi. The study sites comprised samplings of pasture and wooded reclamation sites consisting of 1 to 13 yr post reclamation time, as well as reference sites. Overall, the primary driver of bacterial community dynamics was vegetative cover, although time also influenced dynamics. Richness estimations for operational taxonomic units (OTUs) showed that recently reclaimed (∼1 yr) and Pasture sites were more OTU rich with levels of >1400 compared with reference site levels of ∼1000. Diversity levels also followed a similar trend. Community structure typically differed between time points and vegetative cover; however, membership was similar between sites and reference, indicating that new communities still shared some membership from the previous community. Overall, physicochemical properties trended toward more positive for soil health as time progressed, but bacterial community recovery was still not structurally recovered, although richness and diversity values exceeded reference. Overall, this study demonstrated that mine reclamation using pasture and/or wood restoration can reestablish the bacterial community to approximate reference conditions, but vegetation is still the dominating environmental factor dictating microbial community.

25613. 题目: Distribution, seasonality, and fluxes of dissolved organic matter in the Pearl River (Zhujiang) estuary, China
文章编号: N19071307
期刊: Biogeosciences
作者: Yang Li, Guisheng Song, Philippe Massicotte, Fangming Yang, Ruihuan Li, Huixiang Xie
更新时间: 2019-07-13
摘要: Dissolved organic carbon (DOC) concentration in the Pearl River estuary (PRE) of China was measured in May, August, and October 2015 and January 2016. Chromophoric and fluorescent dissolved organic matter (CDOM and FDOM) in the latter three seasons were characterized by absorption and fluorescence spectroscopy. CDOM and FDOM exhibited negligible seasonal variations, while DOC displayed a significant seasonality, with the average concentration being highest in May (156 µmol L−1), lowest in November (87 µmol L−1), and comparable between January (118 µmol L−1) and August (112 µmol L−1). Although DOC, CDOM, and FDOM in surface water were generally higher than in bottom water, the difference between the two layers was statistically insignificant. DOC showed little cross-estuary variations in all seasons, while CDOM and FDOM in January were higher on the west side of the estuary than on the east side. All three variables showed rapid drawdowns in the head region of the estuary (salinity <5); their dynamics in the main estuary were primarily controlled by conservative mixing, leading to linearly declining or relatively constant (for DOC in May and November only) contents with increasing salinity. The decrease in FDOM with salinity was 5 %–35 % faster than that of CDOM, which in turn was 2–3 times quicker than that of DOC. Salinity and CDOM absorption coefficients could serve as indicators of DOC in August and January. Freshwater endmembers in all seasons mainly contained fresh, protein-rich DOM of microbial origin, a large part of it likely being pollution-derived. Protein-like materials were preferentially consumed in the head region but the dominance of the protein signature was maintained throughout the estuary. Exports of DOC and CDOM (in terms of the absorption coefficient at 330 nm) into the South China Sea were estimated as 195×109 g and 266×109 m2 for the PRE and 362×109 g and 493×109 m2 for the entire Pearl River Delta. The PRE presents the lowest concentrations and export fluxes of DOC and CDOM among the world's major estuaries. DOM delivered from the PRE is, however, protein-rich and thus may enhance heterotrophs in the adjacent coastal waters. Overall, the PRE manifests lower abundance and smaller spatiotemporal variability of DOM than expected for a sizable estuary with a marked seasonality of river runoff due supposedly to the poorly forested watershed of the Pearl River, the rapid degradation of the pollution-derived DOM in the upper reach, and the short residence time of freshwater.

25614. 题目: Adaption and restoration of anammox biomass to Cd(II) stress: Performance, extracellular polymeric substance and microbial community
文章编号: N19071306
期刊: Bioresource Technology
作者: Lian-Zeng-Ji Xu, Jing Wu, Wen-Jing Xia, Lu-Yang Jin, Yi-Hong Zhao, Nian-Si Fan, Bao-Cheng Huang, Ren-Cun Jin
更新时间: 2019-07-13
摘要: Cadmium (Cd) can cause the deterioration of biological systems through inhibiting the enzymes activity and disturbing the microbial metabolism. Although the influence of Cd on conventional wastewater treatment process has been studied, the response of anammox to Cd exposure still remains unclear. This study firstly investigated the adaption and restoration of anammox biomass to Cd(II) stress. Results showed that long-term exposure of anammox bacteria to 2 mg L⁻¹ Cd(II) was beneficial for the reactor performance, while 5 mg L⁻¹ Cd(II) would cause the decline of SAA, extracellular polymeric substance content and relative abundance of Candidatus kuenenia by 40%, 25% and 31%, respectively. Furthermore, these indexes could approximately recover to the initial status after withdrawing Cd(II) from the influent. Overall, the anammox biomass exhibited a certain adaption and restoration ability to the suppression of Cd(II). This study may provide key valuable information for the biological treatment of wastewater containing Cd(II).
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25615. 题目: Evaluation of high-frequency paleoenvironmental variation using an optimized cyclostratigraphic framework: Example for C-S-Fe analysis of Devonian-Mississippian black shales (Central Appalachian Basin, U.S.A.)
文章编号: N19071305
期刊: Chemical Geology
作者: Jiang-Si Liu, Thomas J. Algeo, Jacek Jaminski, Thomas Kuhn, Michael M. Joachimski
更新时间: 2019-07-13
摘要: Stratigraphic successions are rarely sampled at sufficiently dense spacing to permit evaluation of paleoenvironmental variation at the shortest fundamental frequency operative in the depositional system of interest, often because that frequency remains undetermined. Here, we provide an example of a sampling strategy optimized for recovery of high-frequency paleoenvironmental signals, based on (1) full-core analysis using a continuous survey tool such as X-radiography, followed by (2) fine sampling of selected small-scale cycles that record significant short-term paleoenvironmental variation. We show that this strategy results in recovery of high-frequency paleoenvironmental signals that are completely missed by low-density sampling protocols, permitting key insights into depositional and early diagenetic processes that may otherwise by overlooked.The present case study is based on C-S-Fe systematics of the Cleveland and Sunbury shales, which belong to the Upper Devonian-lowermost Carboniferous black shale succession of the Central Appalachian Basin in eastern North America. In these units, the fundamental scale of paleoenvironmental variation is recorded by pervasive decimeter-scale (~5- to 20-cm-thick) compositional cycles that are readily visible in outcrop, in which high-organic layers weather out as resistant ledges. We identified these cycles in drillcores using X-radiography, which proved to be an effective proxy for compositional variation owing to control of bulk density primarily by total organic carbon (TOC) content. We then sampled selected dm-scale cycles (n = 21) at a centimeter spacing, generating short, high-resolution, multiproxy chemostratigraphic records including TOC, sulfur and Fe concentrations, Fe_py/Fe_HR (a redox proxy), δ³⁴S_pyrite, and organic maceral content. This analysis yielded the novel insight that all proxies related to authigenic iron sulfides (e.g., S_total and S_pyrite, Fe_total and Fe_pyrite, Fe_py/Fe_HR, and δ³⁴S_pyrite) covary negatively with TOC within the dm-scale cycles.We interpret the unusual pattern of negative TOC-pyrite covariation in the Cleveland and Sunbury shales to have resulted from differential distributions of labile organic matter (OM), which drove H₂S production via microbial sulfate reduction (MSR), and reactive Fe, which controlled pyrite formation. Labile OM was concentrated in high-TOC layers whereas reactive Fe was concentrated in low-TOC layers (possibly as Fe-oxyhydroxide coatings on silt grains), as a consequence of which part of the H₂S generated in the high-TOC layers diffused upward into the low-TOC layers before becoming fixed as pyrite. This process is evidenced by several contrasts between high-TOC and low-TOC layers: (1) higher S_pyrite concentrations and Fe_py/Fe_HR values in the latter, (2) concentration of pyrite in the lower part of low-TOC layers, immediately above high-TOC layers, and (3) higher δ³⁴S_pyrite values in the latter, reflecting late diagenetic formation of the H₂S that diffused upward into the low-TOC layers. To our knowledge, this process has not been documented previously in ancient marine shales, probably owing to insufficiently high-resolution analysis in earlier studies.

25616. 题目: Short-term influence of biochar and fertilizer-biochar blends on soil nutrients, fauna and maize growth
文章编号: N19071304
期刊: Biology and Fertility of Soils
作者: Solomon Kamau, Nancy K. Karanja, Fredrick O. Ayuke, Johannes Lehmann
更新时间: 2019-07-13
摘要: Use of inorganic fertilizers in smallholder cropping systems in Africa is often becoming inefficient due to increasing unresponsiveness to fertilizer application. A study was conducted for 2 years (four seasons) to assess the effects of biochar made from Prosopis juliflora (Sw.) DC. biomass on nutrients, fauna abundance and subsequent influence on maize planted in a nitisol. There were 12 amendments comprising: (i) biochar applied alone at a rate of 5 and 10 Mg ha⁻¹; (ii) three fertilizer types applied separately (di-ammonium phosphate (18:46:0), urea (46:0:0) and composite NPK (23:23:0)); (iii) six fertilizer + biochar blends of the three fertilizer types and two biochar rates (0.05 and 0.1 Mg ha⁻¹); and (iv) a control with no inputs. Treatments were replicated four times in a randomized complete block design. The amendments were applied in the first two seasons, while the last two were used to assess residual effects. At the end of the first two seasons, total C and N were higher in soils where biochar or fertilizer + biochar was applied, with more than 15.0 g C and 1.9 g N kg⁻¹, compared to 10.4 g C and 1.0 g N kg⁻¹ in control plots. Available P and exchangeable K were over 200% and 100% higher in biochar or fertilizer + biochar amended than control soils, respectively. Application of biochar had no effects on macrofauna such as beetles, centipedes, millipedes, termites and ants, but attracted earthworms. Soil that received 10 Mg biochar ha⁻¹ recorded twice the number of earthworms (207 individuals m⁻²) compared to soil with 5 Mg biochar ha⁻¹ (105 individuals m⁻²) and control (97 individuals m⁻²). Soils which received biochar, with or without fertilizer, had higher taxonomic richness (7.0 species) compared to soils which received DAP (2.8) or NPK (3.8). Nematodes, particularly bacterivorous groups, decreased by more than eight times with biochar application. In the first and second seasons, 5.6 Mg maize grain yield ha⁻¹ was obtained from plots amended with biochar (without fertilizer), which was about six times higher than that harvested from unfertilised control at 0.9 Mg ha⁻¹. Yield differences in plots where fertilizer was applied with or without biochar were not significant. Yield in the third and fourth seasons declined to 3.2 and 1.5 Mg ha⁻¹, irrespective of fertilizer type or biochar amounts.

25617. 题目: Combining cover crops and low nitrogen fertilization improves soil supporting functions
文章编号: N19071303
期刊: Plant and Soil
作者: Silvina Beatriz Restovich, Adrián Enrique Andriulo, Cecilia María Armas-Herrera, María José Beribe, Silvina Isabel Portela
更新时间: 2019-07-13
摘要: Background and aims: Cover crops may restore soil functions lost with single summer crop sequences enhancing soil organic carbon and nitrogen (SOC and SON) stocks. We investigated the effect of cover crops and low nitrogen (N) fertilization on SOC and SON and soil structure (pore size distribution and aggregate stability), and connected changes with cover crop-related variables. Methods: We used a six-year experiment with different winter cover crops in a maize-soybean rotation under no tillage with or without N fertilization of maize (32 kg ha⁻¹). Results: Most cover crops increased SOC (0.36 ± 0.23 Mg ha⁻¹ yr.⁻¹) and vetch also increased SON in the absence of N fertilization. With cover crops, N storage shifted from inorganic to more stable organic forms (SON and cover crop biomass). Cover crops except forage radish increased soil porosity favoring 300–60 μm macropores (0–10 cm depth). Soil aggregation at 0–5 cm depth was more stable with than without cover crops (43 and 25%, respectively). The effect of glomalin as aggregation agent was observed in the absence of N fertilization. Conclusions: Increased N retention and input (in the case of vetch), combined with C input from cover crops, increased organic reserves and improved soil structure, enabling N fertilization reduction.

25618. 题目: A remote sensing adapted approach for soil organic carbon prediction based on the spectrally clustered LUCAS soil database
文章编号: N19071302
期刊: Geoderma
作者: Kathrin J. Ward, Sabine Chabrillat, Carsten Neumann, Saskia Foerster
更新时间: 2019-07-13
摘要: The estimation of the soil organic carbon (SOC) content plays an important role for carbon sequestration in the context of climate change, food security and soil degradation. Reflectance spectroscopy has proven to be a promising technique for SOC quantification in the laboratory and increasingly from air- and spaceborne platforms, where hyperspectral imagery provides great potential for mapping SOC on larger scales with regular updates. When applied on larger scales, soil prediction accuracy decreases due to the inhomogeneity of samples. In this paper, we examined if spectral clustering of the LUCAS EU-wide topsoil database is successful without using other covariates than the spectral database and can improve SOC model performance compared to a reference model that was calibrated on the whole database without clustering. Different clustering methodologies were tested, including a k-means clustering based on principal component analysis or based on spectral feature variables, combined with partial least squares regression (PLSR) models, and a clustering based on a local PLSR approach which builds a different multivariate model for each sample to be predicted. Furthermore, in order to allow for subsequent application to hyperspectral remote sensing data, atmospheric water wavelengths were removed from the analyses. The local PLSR approach achieved best results and was additionally applied to LUCAS spectra resampled to the upcoming hyperspectral EnMAP sensor which led to good results: R² = 0.66, RMSEP = 5.78 g kg⁻¹ and RPIQ = 1.93. The k-means clustering approach showed slightly better results than the reference model. Overall, our results showed similar performances for SOC prediction models compared to other approaches using PLSR with a larger spectral range and other soil parameters as covariates. This study shows that (i) it is possible to transfer the local PLSR approach onto a wavelengths reduced spectral library and to predict estimations of SOC at low-cost with reasonable accuracy based on large scale soil databases; and (ii) that the local regression approach is a valuable tool for SOC prediction models based solely on spectral data without the use of other soil covariates.
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25619. 题目: Soil warming and nitrogen deposition alter soil respiration, microbial community structure and organic carbon composition in a coniferous forest on eastern Tibetan Plateau
文章编号: N19071301
期刊: Geoderma
作者: Shouqin Sun, Yanhong Wu, Jun Zhang, Genxu Wang, Thomas H. DeLuca, Wanze Zhu, Andi Li, Min Duan, Lei He
更新时间: 2019-07-13
摘要: Understanding the response of soil respiration (R_s) to future climate projections is critical for understanding feedbacks and developing effective mitigation strategies. We conducted a warming and N deposition manipulation experiment using a 2 × 2 full-factorial design to evaluate the interactive effects of soil warming and N deposition on R_s, microbial community composition and soil organic carbon (SOC) composition in a subalpine coniferous forest on the eastern slope of the Qinghai-Tibetan Plateau. Soil warming and N addition independently increased R_s and changed microbial community composition, resulting in a net increase in bacteria with N addition and an increase in protozoa with warming; but the interaction of these two factors proved to be antagonistic, resulting in a lower R_s and protozoa concentration in the combined warming and nitrogen addition (WN) treatment relative to the warming (W) treatment. The chemical structure of SOC changed with the treatments, with alkyl C increased with warming, aromatic C decreased with both warming and N addition, and the interaction of warming and N induced a lower O-alkyl C and a higher contribution of alkyl C to SOC. The negative correlation between R_s and aromatic C and the positive correlation between R_s and alkyl C and MBC indicates that the elevated CO₂ emission under warming and N addition was related to the decomposition of aromatic C and the following relative accumulation of alkyl C. Our observations suggest that climate induced soil warming will likely increase soil CO₂ emissions, but this effect could be largely offset by a simultaneous increase in N deposition in subalpine coniferous forests.

25620. 题目: Depth is Relative: The Importance of Depth on TEP in the Near Surface Environment
文章编号: N19071216
期刊: Ocean Science Discussions
作者: Tiera-Brandy Robinson, Christian Stolle, Oliver Wurl
更新时间: 2019-07-12
摘要: . Transparent exopolymer particles (TEP) are a major source for both organic matter (OM) and carbon transfer in the ocean and into the atmosphere. Consequently, understanding the vertical distribution of TEP and the processes which impact its movement are important in understanding the OM and carbon pools on a larger scale. Additionally, most studies looking at the vertical profile of TEP have focused on large depth scales from 5 to 1000s meters and have omitted the near surface environment. Results from a study of TEP enrichment in the sea surface microlayer (SML) in different regions (tropical, temperate) has shown that while there is a correlation between TEP abundance and primary production (PP) on larger or seasonal scales, such relationships break down on shorter time and spatial scales. Using a novel small-scale vertical sampler, the vertical distribution of TEP within the uppermost 2 meters was investigated. With a maximum variance of TEP abundance between depths (1.39 × 106 µg XG eq2 L-2) and a minimum variance of (6 × 102 µg XG eq2 L-2) the vertical distribution of TEP was found to be both heterogeneous and homogeneous at times. Results from the enrichment of TEP and Chl a between different regions has shown TEP enrichment to be greater in oligotrophic waters, when both Chl a and TEP abundance was low, suggesting the importance of abiotic sources for the enrichment of TEP in the SML. However, considering multiple additional parameters that were sampled, it is clear that no single parameter could be used as a proxy for TEP heterogeneity, other probable biochemical drivers of TEP transport are discussed.