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22761. 题目: Molecular Hysteresis: Hydrologically Driven Changes in Riverine Dissolved Organic Matter Chemistry during a Storm Event
文章编号: N19040503
期刊: Journal of Geophysical Research: Biogeosciences
作者: Sasha Wagner, Jennifer Hoyle Fair, Serena Matt, Jacob D. Hosen, Peter Raymond, James Saiers, James B. Shanley, Thorsten Dittmar, Aron Stubbins
更新时间: 2019-04-05
摘要: Hydrological events, driven by rainfall, control the amount and composition of dissolved organic matter (DOM) mobilized through river networks. In forested watersheds, the concentration, composition, and reactivity of DOM exported changes as baseflow transitions to storm flow, with major implications to downstream biogeochemistry. Hysteresis describes an observed difference between in‐stream solute concentration/signal and discharge. By studying the relationship between DOM and stream discharge, we refine our understanding of the environmental and hydrological factors that influence the quantity and quality of stream DOM. The main objective of this study was to track hysteretic changes in riverine DOM molecular composition during storm events. Samples were collected from nested sites within the Passumpsic River catchment (Vermont, USA), a tributary of the Connecticut River. High‐resolution monitoring of fluorescent DOM (via in situ sensors) and automated collection of discrete samples captured short‐term, hydrologically driven variations in DOM concentration and composition. Ultrahigh‐resolution mass spectrometry revealed an enrichment in aliphatic compounds at storm onset, while aromatic and polyphenolic compounds were more enriched at peak discharge. Molecular hysteresis patterns were similar across stream orders, indicating that fresh, terrigenous DOM is quickly shunted downstream, through the river network, during pulses of high discharge.

22762. 题目: Effects of different biochar amendments on carbon loss and leachate characterization from an agricultural soil
文章编号: N19040502
期刊: Chemosphere
作者: Xing Ya Yang, Kwang-Hyeon Chang, You Jin Kim, Jin Zhang, Gayoung Yoo
更新时间: 2019-04-05
摘要: Selection of an appropriate biochar as a soil amendment requires a thorough investigation of the effects on soil ecosystems and adjacent water systems via leaching. Different biochar characteristics influence retention or leaching of different soil and biochar components. A lab lysimeter study was conducted to investigate carbon (C) balance and leachate quality with biochar additions. Biochar made from wood pellets (WP) and sewage sludge (SS) produced at 400 °C (WP400 and SS400) and 700 °C (WP700 and SS700), respectively, were applied to silt loam soil at an application rate of 4%. Fluorescence excitation-emission spectrophotometry (EEMs) was utilized to understand the compositional changes in leachate dissolved organic carbon (DOC). Our results show that DOC contributed the largest portion of C leaching loss. The WP treatments increased DOC mass loss, but did not significantly change leachate DOC quality. SS400, in comparison, increased mass loss of DOC and SS700 decreased it probably due to its higher adsorptive capacity to DOC. Unlike WP treatments, SS treatments significantly changed leachate DOC quality. Chemical oxygen demand (COD) was reduced with SS400 and SS700 biochar additions, which is assumed to be related to SS biochar's high oxygen-containing surface functional groups. Reduction in total nitrogen (TN) leaching by WP700 and SS700 treatments might be related to the higher micropore surface area. Over all, our findings imply that changes in the different components of the leachate from biochar-amended soil are related to different biochar properties, such as labile matter content, total surface area, micropore volume and cation exchange capacity.

22763. 题目: Effects of soil organic carbon (SOC) content and accessibility in subsoils on the sorption processes of the model pollutants nonylphenol (4-n-NP) and perfluorooctanoic acid (PFOA)
文章编号: N19040501
期刊: Science of The Total Environment
作者: Melanie Martz, Jannis Heil, Bernd Marschner, Britta Stumpe
更新时间: 2019-04-05
摘要: Subsoils control the release of hydrophobic pollutants to groundwater systems, but the role of subsoil soil organic carbon (SOC) in sorption processes of hydrophobic organic pollutants remains unclear. Thus, this study aimed to understand the role of subsoil SOC in sorption processes of 4-n-nonylphenol (NP) and perfluorooctanoic acid (PFOA) as model pollutants. To characterize the sorption behavior of NP and PFOA, 42 sub- and 54 topsoil samples were used for batch experiments. Differences in NP and PFOA sorption between sub- and topsoil samples and its mechanisms were identified using multiple regression analysis. Generally, the sorption of NP and PFOA was linear in all samples. The sorption of NP to soil samples (log_KD = 1.78–3.68) was significantly higher and less variable than that of PFOA (log_KD = −0.97–1.44). In topsoils, SOC content had the highest influence on NP and PFOA sorption. For NP, hydrophobic interactions between NP and SOC were identified as the most important sorption mechanism. For PFOA, hydrophobic as well as electrostatic interactions were determined depending on soil pH. In subsoils, the relevance of SOC content for pollutant sorption decreased drastically. For NP, not SOC content but rather SOC quality was relevant in SOC poor subsoils. For PFOA, clay and iron oxide content were found to be relevant for pollutant interactions with the solid phase. Thus, especially in SOC depleted subsoils, the sorption potential for PFOA remained unpredictable.
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22764. 题目: Ball-milled biochar for alternative carbon electrode
文章编号: N19040410
期刊: Environmental Science and Pollution Research
作者: Honghong Lyu, Zebin Yu, Bin Gao, Feng He, Jun Huang, Jingchun Tang, Boxiong Shen
更新时间: 2019-04-04
摘要: Ball-milled biochars (BM-biochars) were produced through ball milling of pristine biochars derived from different biomass at three pyrolysis temperatures (300, 450, and 600 °C). The results of scanning electron microscopic (SEM), surface area, hydrodynamic diameter test, and Fourier transform infrared spectroscopy (FTIR) revealed that BM-biochars had smaller particle size (140–250 nm compared to 0.5–1 mm for unmilled biochar), greater stability, and more oxygen-containing functional groups (2.2–4.4 mmol/g compared to 0.8–2.9 for unmilled biochar) than the pristine biochars. With these changes, all the BM-biochar-modified glassy carbon electrodes (BM-biochar/GCEs) exhibited prominent electrochemical properties (e.g., ΔE_p of 119–254 mV compared to 850 mV for bare GCE). Cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) show that ball-milled 600 °C biochar/GCE (BMBB600/GCE and BMBG600/GCE) had the smallest peak-to-peak separation (ΔE_p = 119 and 132 mV, respectively), series resistance (R_S = 88.7 and 89.5 Ω, respectively), and charge transfer resistance (R_CT = 1224 and 1382 Ω, respectively), implying its best electrocatalytic activity for the reduction of Fe(CN)₆³⁻. It is supposed that the special structure (i.e., internal surface area, pore volume, oxygen-containing functional groups, and graphitic structure) facilitates the electron transfer and reduces interface resistance. Economic cost of BM-biochar/GCE was 1.97 × 10⁻⁷ USD/cm², much lower than that of a “low-cost platinum electrode” (0.03 USD/cm²). The results indicate potential application of the novel BM-biochar for low cost and high efficient electrodes.

22765. 题目: Formation of Nitrophenolic Byproducts during Heat-Activated Peroxydisulfate Oxidation in the Presence of Natural Organic Matter and Nitrite
文章编号: N19040409
期刊: Environmental Science & Technology
作者: Peizeng Yang, Yuefei Ji, Junhe Lu, Qingguo Huang
更新时间: 2019-04-04
摘要: Sulfate radical (SO₄^•–)-based advanced oxidation is a viable in situ remediation technology for degrading organic contaminants in the subsurface. In this study, we demonstrated that SO₄^•– could induce the activation of nitrite, an anion commonly present in the subsurface environment, leading to the formation of nitrophenolic byproducts. Fourier-transform infrared spectroscope and ¹⁵N nuclear magnetic resonance analysis revealed that the inorganic nitrite was incorporated into natural organic matter (NOM) to form organic nitrogen upon SO₄^•– oxidation. Nitrophenolic byproducts, including 2-hydroxy-5-nitrobenzoic acid, 4-nitrophenol, and 2,4-dinitrophenol, were identified using high-resolution mass spectrometry in combination with a ¹⁵N labeling technique. Formation of nitrated byproducts was ascribed to the scavenging of SO₄^•– by nitrite, which not only generated the nitrating agent NO₂^• but also inhibited the degradation of organic compounds, making them more available to the reactions with NO₂^•. The phenolic moieties in NOM served as the main reactive sites for NO₂^• attack. The nitration begins with H abstraction on the phenoxy oxygen, followed by the addition of another NO₂^• to its ortho or para site. Decarboxylation followed by NO₂^• addition can also generate nitrophenolic byproducts. To the best of our knowledge, this is the first study reporting the nitration of NOM and formation of toxic nitrophenolic byproducts during SO₄^•–-based oxidation. It sheds light on the potential risks of this technology in subsurface remediation practices.
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22766. 题目: Cellulose digestion abilities determine the food utilization of mangrove estuarine crabs
文章编号: N19040408
期刊: Estuarine, Coastal and Shelf Science
作者: Shun Kawaida, Kusuto Nanjo, Naoya Ohtsuchi, Hiroyoshi Kohno, Mitsuhiko Sano
更新时间: 2019-04-04
摘要: Food utilization and cellulose digestion abilities of six crab species were examined to clarify the mechanisms driving trophic and spatial segregation among species within a mangrove estuary on the Urauchi River, Iriomote Island, southern Japan. Dual stable isotope signatures (δ¹³C and δ¹⁵N) of dominant crab species inhabiting three microhabitats (bare sandy flat, bare muddy flat and mangrove forest) showed that most crab species, such as the soldier crab Mictyris guinotae and fiddler crab Gelasimus jocelynae, primarily assimilated microphytobenthos (MPB), while the sesarmid crab Parasesarma bidens inside the mangrove forest substantially utilized cellulose-rich mangrove detritus and leaf litter. Analyses of the chemical properties of sediment organic matter indicated that it comprised mainly mangrove detritus, which was more abundant on the muddy flat and in the forest compared to the sandy flat. In contrast, the standing stocks of MPB were at consistently low levels in each microhabitat, particularly inside the mangrove forest than on the bare flats. The enzyme assay revealed that P. bidens exhibited much higher cellulase activity, enabling the species to utilize refractory mangrove materials, whereas the other crab species with lower cellulase activity were highly dependent upon nutritious and easily degradable MPB, although the amount of the latter was largely limited in the mangrove estuary. These findings suggested that the assimilation efficiency of cellulose-rich plant materials as a carbon source, dependent upon the level of cellulase activity, essentially controls trophic and spatial segregation among crab species in the mangrove estuary. Given the greater biomass of plant detritus, it is likely that P. bidens plays an integral part in establishing the detritus food chain in the mangrove ecosystem through the effective digestion/assimilation of cellulose materials.
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22767. 题目: Effects of soil properties on the toxicity and bioaccumulation of lead in soil invertebrates
文章编号: N19040407
期刊: Environmental Toxicology and Chemistry
作者: RomanP Lanno, Koen Oorts, Erik Smolders, Katie Albanese, MJasim Chowdhury
更新时间: 2019-04-04
摘要: The present study examined the effects of soil physical and chemical properties on the toxicity of lead (Pb) to earthworms (Eisenia fetida) and collembolans (Folsomia candida), and on bioaccumulation of Pb by earthworms, in soils amended with Pb salts. Toxicity tests were conducted in seven soils varying in soil properties (pH: 4.7‐7.4, eCEC: 4‐42 cmol_c/kg, organic carbon: 10 – 50 g C/kg) that were leached and pH corrected after spiking with PbCl₂. EC50s based upon total soil Pb concentrations ranged from 35 to 5080 mg Pb/kg for earthworms and 389 to >7190 mg/kg for Collembola. Significant positive correlations were observed between log (EC50) for earthworm reproduction and log (eCEC, total C, exchangeable Ca and Mg, or clay content), but no significant correlations were observed between Pb toxicity to Collembola and soil properties. Expressing Pb dose as either the free ion (Pb²⁺) activity in pore water or as the measured dissolved porewater concentration of Pb did not explain differences in toxicity among soils. The bioaccumulation factors (BAFs) for Pb in earthworms ranged more than 10‐fold across six soil treatments, with a median of 0.16, and the BAF was significantly correlated with eCEC (p = 0.038, r = ‐0.84), but not with any other soil properties. Soil properties related to cation‐exchange capacity (eCEC, total C, exchangeable Ca and Mg, clay content) had a significant effect on Pb toxicity and bioaccumulation in earthworms, but no relationship was found for Collembola. CEC is a major soil property affecting the bioavailability of Pb and should be incorporated into any soil hazard assessment of Pb as a modifying factor of toxicity and bioaccumulation for earthworms.

22768. 题目: Using woody organic matter amendments to increase water availability and jump‐start soil restoration of desertified grassland soils of Ningxia, China
文章编号: N19040406
期刊: Land Degradation & Development
作者: Zhigang Li, Rebecca L. Schneider, Stephen J. Morreale, Yingzhong Xie, Jian Li, Changxiao Li, Xilu Ni
更新时间: 2019-04-04
摘要: Solutions are urgently needed to address the continued degradation of agricultural soils worldwide, which has severely impacted the ability to grow crops and has led to increased irrigation demand from already rapidly depleting freshwater resources. This project evaluated a unique, previously untested, type of soil organic amendment, i.e. coarse wood chips, for capturing and storing scarce precipitation and improving desertified, sandy soils. A field plot experiment was conducted in Ningxia, China, from 2011, through 2016, comparing unamended sandy soils with three coarse woody amendments, including: 1) surface‐applied mulch; 2) wood chips incorporated into the top 20 cm of soil; and 3) incorporated wood chips combined with a branch lattice shelter over the soil surface – all treatments replicated under both irrigated and non‐irrigated conditions. Precipitation patterns and soil moisture content were compared between 2012 and 2015, related soil physical and chemical properties were monitored continuously, as well as alfalfa yields in 2015 and 2016. Results indicated that amended soils maintained significantly higher soil water contents between rain events, decreased the number of days below the permanent wilting point, and improved soil properties and alfalfa growth. The combination treatment of wood chips and a branch shelter performed the best among treatments, exhibiting increases in average water storage 50% or more above controls. Unlike highly degradable soil amendments, the slow decomposition of the coarse wood chips resulted in continuous benefits for all five years. This use of coarse wood chips represents a timely new addition to the toolbox of soil amendments, providing a mechanism for immediate, long‐lasting restoration of the world's degraded and desertified soils that will foster global food and water security.

22769. 题目: Impact of weathering on REE distribution in soil-saprolite profiles developed on orthogneisses in Borborema Province, NE Brazil
文章编号: N19040405
期刊: Geoderma
作者: Jean Cheyson Barros dos Santos, Emilia Le Pera, Cybelle Souza de Oliveira, Valdomiro Severino de Souza Júnior, Fabrício de Araújo Pedron, Marcelo Metri Corrêa, Antonio Carlos de Azevedo
更新时间: 2019-04-04
摘要: Rare earth elements (REEs) are a group of elements (from La to Lu) with high economic value and serve mainly as essential raw material for various high-technology items. This study explores mineral weathering and the geochemical evolution of regoliths (quaternary period) derived from orthogneisses (late Cretaceous Period) in four sites in Borborema Province, NE Brazil, providing a new contribution to the understanding of the influence of soil and saprolite attributes on the distribution of REEs in the regolith. We used optical and electron microscopy to depict the weathering of minerals in the rock, saprolite and soil microstructure, focusing on the distribution of REEs in the regolith (Depth: 3.0 m). We also determined the poorly and well-crystallized iron oxide contents, the clay fraction amount and the total organic carbon content to observe how these attributes influence the distribution of REEs in the soil and saprolite. The results allowed the classification of weathering for feldspars, micas and other primary minerals into four stages based on their degree of alteration and the consequent influence on the geochemistry of the regoliths. Advancement of the weathering stages revealed the relative increases in Fe and Ti compared with Ca, Mg, Na and K from the fresh rock up to the soil horizons, and ilmenite and xenotime were the main sources of Yb, Y, Co and P. The patterns of signatures and anomalies were different for light (LREEs), middle (MREEs) and heavy rare earth elements (HREEs) and for regoliths in different metamorphic complexes. The LREEs related well with the clay fraction amount, the poorly crystallized iron oxides and the degree of weathering, as estimated by the mineralogical index of alteration (MIA), while the HREEs related well with the total organic carbon (TOC). In particular, Ce was strongly associated with Mn oxides, possibly due to simultaneous oxidative precipitation.

22770. 题目: Cadmium binding mechanisms and adsorption capacity by novel phosphorus/magnesium-engineered biochars
文章编号: N19040404
期刊: Science of The Total Environment
作者: Evanise Silva Penido, Leônidas Carrijo Azevedo Melo, Luiz Roberto Guimarães Guilherme, Maria Lucia Bianchi
更新时间: 2019-04-04
摘要: Novel phosphorus/magnesium-engineered biochars were prepared from poultry litter and tested for their Cd²⁺ retention capacity, unraveling the adsorption mechanisms. Batch experiments were conducted to evaluate the adsorption ability of Cd²⁺ by biochars and a wide range of characterization techniques were used: scanning electron microscopy with energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, surface area and pore volume, and X-ray photoelectron spectroscopy. Results showed that, in general, Cd²⁺ removal did not drastically change with initial pH variation and was relatively fast (up to 3 h); the pseudo-second-order kinetic model provided slightly better fitting to the data. Cadmium adsorption capacities of the P/Mg-engineered biochars were much higher than that of the unmodified biochar (up to 113.9 mg g⁻¹), following the SIPS isotherm model. The surfaces of the biochars contain a rich variety of oxygen-containing functional groups as well as phosphate groups. Since the specific surface areas of the biochars are considered low (up to 25.19 m² g⁻¹), surface groups contributed more to Cd²⁺ retention. Biochars can be represented by type II isotherms with significant type H3 hysteresis patterns, which suggest the presence of asymmetrically slit-shaped pores. Complexation and precipitation were the predominant adsorption mechanisms. Thus, P/Mg-engineered biochars produced from poultry litter are considered effective and eco-friendly adsorbents for Cd²⁺ removal from aqueous medium, especially PLB-H₃PO₄-MgO, which is produced from low-cost materials.
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22771. 题目: Supramolecular architectures of natural organic matter
文章编号: N19040403
期刊: Science of The Total Environment
作者: Martha J.M. Wells, Holly A. Stretz
更新时间: 2019-04-04
摘要: A new conceptual model for supramolecular aggregation of natural organic matter (OM) is proposed. Scientific awareness of OM as natural hydrogels is slowly increasing although in the literature they are primarily categorized as physical hydrogels stabilized only by weak interactions. The supramolecular view of OM is here expanded, based on insight from comprehensive hydrogen bond theory, to include three-center–four-electron near-covalent linkages and introduce a new category of metachemical hydrogels that are neither chemical nor physical hydrogels. Hydrogels are typically classified into chemical (permanent, covalently bonded) or physical (reversible, ionic, hydrophobic, or hydrogen bonded) classes based on crosslinking. However, augmented by contemporary advances in hydrogen bonding theory purporting that not all hydrogen bonds are weak and that some hydrogen bonding motifs result in moderate and strong interactions, the popular supramolecular view of OM is extended to include all types of hydrogen bonds. We propose a new category of hydrogels exists—metachemical hydrogels—as a fundamental component of OM. Strong, near covalent, equally shared hydrogel cross-linkages in the metachemical hydrogel can outcompete water. Here, metachemical (≤1 μm diameter) and physical (>1 μm diameter) hydrogels are described as two primary forms of aggregates observed for OM in a hierarchical ‘supramolecular within supramolecular’ self-assembling architecture with new information about shear. The metachemical hydrogels are postulated to be encapsulated within a dispersible physical hydrogel scaffold which can form, dissipate, and spontaneously re-form over turbulent/quiescent cycles indicating reversible abiotic self-assembly. The significance of this investigation is to understand the form OM evolved in nature to provide essential functions. The potential for strong intermolecular forces to form a metachemical hydrogel in OM and the concept of a dynamic dual metachemical/physical hydrogel structure was not previously introduced. The metachemical hydrogel construct should inform hydrogen bonded systems in other chemical and biochemical disciplines.
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22772. 题目: Pyrolysis of sewage sludge by electromagnetic induction: Biochar properties and application in adsorption removal of Pb(II), Cd(II) from aqueous solution
文章编号: N19040402
期刊: Waste Management
作者: Yongjie Xue, Chen Wang, Zhenhua Hu, Yi Zhou, Yue Xiao, Teng Wang
更新时间: 2019-04-04
摘要: Pyrolysis of sewage sludge was studied by electromagnetic induction (EMI) heating method and in a laboratory-scale reaction installation. Basic properties and adsorption of heavy metals Pb and Cd on biochar from EMI pyrolysis of sewage sludge was investigated. Experimental results indicate that EMI pyrolysis temperature was determined by the relationship between working voltage of EMI device and induction media. Biochar yield rate ranged from 89.7% to 51.2% at temperature from 300 to 600 °C. Elements, surface characterizations and micromorphology, thermogravimetric properties as well as gas evolution changed with increasing pyrolysis temperature. Hydroxyl groups were decomposed during EMI pyrolysis process. Heavy metals in biochar was leached through TCLP and higher leachability was obtained in biochar pyrolyzed at 400 °C compared to other biochar products. A higher adsorption removal efficiency of Pb and Cd was obtained by EMI pyrolyzed biochar. Langmuir and pseudo-first-order models were used for description of adsorption isotherm and kinetics.
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22773. 题目: Polymer-clay composite geomedia for sorptive removal of trace organic compounds and metals in urban stormwater
文章编号: N19040401
期刊: Water Research
作者: Jessica R. Ray, Itamar A. Shabtai, Marc Teixidó, Yael G. Mishael, David L. Sedlak
更新时间: 2019-04-04
摘要: Functionalized polymer-clay composites were developed and characterized as engineered geomedia for trace contaminant removal during infiltration of urban runoff. Montmorillonite clays were functionalized with either poly(diallyldimethylammonium) chloride (PDADMAC) or poly(4-vinylpyridine-co-styrene) (PVPcoS) to enhance organic compound sorption using a simple, scalable synthesis method. Seven representative trace organic compounds and six trace metals were employed to assess the performance of the polymer-clay composites relative to biochar (i.e., an adsorbent proposed for similar purposes) in batch sorption and column studies under simulated stormwater conditions. Contaminant and geomedia electrostatic and hydrophobic interactions, and the presence of natural organic matter (NOM) affected sorption. In batch studies, polymer-clay composites exhibited similar performance to biochar for perfluoroalkyl substance removal, but had lower affinity for polar pesticides and tris(2-chloroethyl) phosphate. Oxyanion removal was greatest for positively-charged PDADMAC-clay composites (particularly Cr[VI]), while PVPcoS-clay composites removed over 95% of Ni, Cd, and Cu. NOM decreased removal of all organic compounds, but increased trace metal removal on clay composites due to sorption of NOM-complexed metals. Polymer-clay composite-amended columns best removed oxyanions, while biochar-amended columns exhibited superior removal for all trace organics. At 3 wt% geomedia-sand loading, clay composites exhibited significantly higher saturated hydraulic conductivity than biochar, which is advantageous when clogging is a concern or when rapid infiltration is needed. Under typical urban stormwater conditions, the clay composites will remove contaminants for at least 20–30 years before regeneration or replacement is needed.
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22774. 题目: Denitrification Potential and Carbon Mineralization in Restored and Unrestored Coastal Wetland Soils Across an Urban Landscape
文章编号: N19040312
期刊: Wetlands
作者: April A. Doroski, Ashley M. Helton, Timothy M. Vadas
更新时间: 2019-04-03
摘要: The recovery of wetland function after tidal flow restoration may be influenced by water pollution and sea level rise. Our objective was to examine the effects of tidal flow restoration on denitrification potential and carbon (C) mineralization across an urban coastal landscape. Soil cores were collected from 32 tidal wetlands in Connecticut, U.S.A., spanning a wide range of salinity (0.3–29 ppt) and watershed development (<1–79%). In brackish wetlands, denitrification potential increased with time since restoration, while C mineralization showed no significant relationship. Soil chemistry was also a strong predictor of process rates; best fit multiple linear regression models for denitrification included both soil chemistry variables and time since restoration. Although principal components analysis revealed soil chemistry overlapped by wetland type (freshwater, saline, or brackish), process rates in freshwater versus brackish wetlands had different relationships with soil chemistry. In freshwater wetlands, denitrification potential and C mineralization increased with soil metal content. In brackish wetlands, denitrification potential decreased with increasing salinity and C mineralization increased with increasing organic matter, soil moisture, and ammonium. Our results highlight the potential for biogeochemical processes to recover after wetland restoration, along with complex interactions between these processes and chemicals in developed coastal landscapes.

22775. 题目: Additional application of aluminum sulfate with different fertilizers ameliorates saline-sodic soil of Songnen Plain in Northeast China
文章编号: N19040311
期刊: Journal of Soils and Sediments
作者: Meng Zhou, Xiaobing Liu, Qingfeng Meng, Xiannan Zeng, Jizhou Zhang, Dawei Li, Jie Wang, Weiling Du, Xianfa Ma
更新时间: 2019-04-03
摘要: Purpose: Serious soil salinization, including excessive exchangeable sodium and high pH, significantly decreases land productivity. Reducing salinity and preventing alkalization in saline-sodic soils by comprehensive improvement practices are urgently required. The combinations of aluminum sulfate with different types of fertilizer at different rates were applied on rice paddy with saline-sodic soils of the Songnen Plain in Northeast China to improve soil quality and its future utilization. Materials and methods: Experiments were carried out in a completely randomized block design. Twelve treatments with aluminum sulfate at the rates of 0, 250, 500, and 750 kg hm⁻² with inorganic, bio-organic, and organic-inorganic compound fertilizers were performed. Soil pH, electronic conductivity (EC), cation exchangeable capacity (CEC), exchangeable sodium percentage (ESP), total alkalinity, sodium adsorption ratio (SAR), soil organic carbon (SOC), available nutrients, soluble ions, rice growth, and yield in the saline-sodic soils were measured across all treatments. The relationships among the measured soil attributes were determined using one-way analysis of variance, correlation analysis, and systematic cluster analysis. Results and discussion: The pH, EC, ESP, total alkalinity, SAR, Na⁺, CO₃²⁻, and HCO₃⁻ in saline-sodic soil were significantly decreased, while CEC, SOC, available nitrogen (AN), available phosphorus (AP), available potassium (AK), K⁺, and SO₄²⁻ were significantly increased due to the combined application of aluminum sulfate with fertilizer compared with the fertilizer alone. The most effective treatment in reducing salinity and preventing alkalization was aluminum sulfate at a rate of 500 kg hm⁻² with organic-inorganic compound fertilizer. This treatment significantly decreased the soil pH, EC, ESP, total alkalinity, SAR, Na⁺, and HCO₃⁻ by 5.3%, 28.9%, 41.1%, 39.3%, 22.4%, 23.5%, and 35.9%, but increased CEC, SOC, AN, AP, AK, K⁺, SO₄²⁻, rice height, seed setting rate, 1000-grain weight, and yield by 77.5%, 115.5%, 106.3%, 47.1%, 43.3%, 200%, 40%, 6.2%, 43.9%, 20.3%, and 42.2%, respectively, compared with CK treatment in the leaching layer. Conclusions: The combined application by aluminum sulfate at a rate of 500 kg hm⁻² with organic-inorganic compound fertilizer is an effective amendment of saline-sodic soils in Songnen Plain, Northeast China. These results are likely related to the leaching of Na⁺ from the soil leaching layer to the salt accumulation layer and desalination in the surface soil, and the increase of SOC improved the colloidal properties and increased fertilizer retention in soil. In addition, the environmental impact of aluminum sulfate applied to soil needs to be further studied.

22776. 题目: Coupling metabolisms of arsenic and iron with humic substances through microorganisms in paddy soil
文章编号: N19040310
期刊: Journal of Hazardous Materials
作者: Xing-Yun Yi, Yu-Ping Yang, Hai-Yan Yuan, Zheng Chen, Gui-Lan Duan, Yong-Guan Zhu
更新时间: 2019-04-03
摘要: Humic acid (HA) and fulvic acid (FA) are dominating humic substances (HS) in soil. In this study, the effects of HA and FA addition (0.2%–1.5%) on arsenic (As) mobility and microbial community composition in paddy soil were investigated. FA significantly increased the concentrations of As (12-fold), iron (Fe; 20-fold), manganese (Mn; 3-fold) and acetic acid (3-fold) in soil porewater, and also caused significant enrichment of Desulfitobacterium (41-fold). Furthermore, the FA addition significantly increased the relative abundance of Bathyarchaeota (4-fold), a microorganism that is suggested to be important for FA degradation. In contrast, HA slightly increased As (1.2-fold) in porewater, had little effect on Fe, Mn and acetic acid, and 1.5% HA addition significantly decreased As in porewater at day 14 (45%). Both HA and FA addition promoted As methylation. HA increased dimethylarsenate concentration and FA increased monomethylarsenate concentration in porewater. These results highlight the contrasting effects of different (HA vs. FA) organic substances on As fate in paddy soil and advance our understanding of the associations among As, Fe and organic substances through microorganisms in paddy soil.

22777. 题目: Impact of biochar on mobilization, methylation, and ethylation of mercury under dynamic redox conditions in a contaminated floodplain soil
文章编号: N19040309
期刊: Environment International
作者: Felix Beckers, Yasser Mahmoud Awad, Jingzi Beiyuan, Jens Abrigata, Sibylle Mothes, Daniel C.W. Tsang, Yong Sik Ok, Jörg Rinklebe
更新时间: 2019-04-03
摘要: Mercury (Hg) is a highly toxic element, which is frequently enriched in flooded soils due to its anthropogenic release. The mobilization of Hg and its species is of ultimate importance since it controls the transfer into the groundwater and plants and finally ends in the food chain, which has large implications on human health. Therefore, the remediation of those contaminated sites is an urgent need to protect humans and the environment. Often, the stabilization of Hg using amendments is a reliable option and biochar is considered a candidate to fulfill this purpose. We tested two different pine cone biochars pyrolyzed at 200 °C or 500 °C, respectively, with a view to decrease the mobilization of total Hg (Hg_t), methylmercury (MeHg), and ethylmercury (EtHg) and/or the formation of MeHg and EtHg in a contaminated floodplain soil (Hg_t: 41 mg/kg). We used a highly sophisticated automated biogeochemical microcosm setup to systematically alter the redox conditions from ~−150 to 300 mV. We continuously monitored the redox potential (E_H) along with pH and determined dissolved organic carbon (DOC), SUVA₂₅₄, chloride (Cl⁻), sulfate (SO₄²⁻), iron (Fe), and manganese (Mn) to be able to explain the mobilization of Hg and its species.However, the impact of biochar addition on Hg mobilization was limited. We did not observe a significant decrease of Hg_t, MeHg, and EtHg concentrations after treating the soil with the different biochars, presumably because potential binding sites for Hg were occupied by other ions and/or blocked by biofilm. Solubilization of Hg bound to DOC upon flooding of the soils might have occurred which could be an indirect impact of E_H on Hg mobilization. Nevertheless, Hg_t, MeHg, and EtHg in the slurry fluctuated between 0.9 and 52.0 μg/l, 11.1 to 406.0 ng/l, and 2.3 to 20.8 ng/l, respectively, under dynamic redox conditions. Total Hg concentrations were inversely related to the E_H; however, ethylation of Hg was favored at an E_H around 0 mV while methylation was enhanced between −50 and 100 mV. Phospholipid fatty acid profiles suggest that sulfate-reducing bacteria may have been the principal methylators in our experiment. In future, various biochars should be tested to evaluate their potential in decreasing the mobilization of Hg and to impede the formation of MeHg and EtHg under dynamic redox conditions in frequently flooded soils.
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22778. 题目: Effect of crop residue addition on soil organic carbon priming as influenced by temperature and soil properties
文章编号: N19040308
期刊: Geoderma
作者: Sangeeta Lenka, Pankaj Trivedi, Brajesh Singh, Bhupinder Pal Singh, Elise Pendall, Adrian Bass, Narendra Kumar Lenka
更新时间: 2019-04-03
摘要: Priming of soil organic carbon (SOC) is a crucial factor in ecosystem carbon balance. Despite its increasing importance in the changing global climate, the extent of influence of temperature and soil properties on the priming effect remains unclear. Here, soil priming was investigated using ¹³C labeled wheat residues in two cultivated, subtropical (Vertisol) and semi-arid (Luvisol), soils of Australia at four incubation temperatures (13, 23, 33 and 43 °C). The priming effect was computed from respired CO₂ and associated δ¹³C, which were measured periodically over the 52-day incubation period. Wheat residue addition resulted in greater priming effect in the Luvisol (1.17 to 2.37% of SOC) than the Vertisol (0.02 to 1.56% of SOC). The priming of SOC was the highest at 23 °C in the Luvisol, and at 43 °C in the Vertsiol, which indicates a variable positive priming effect of temperature in different soil types. Wheat residue addition significantly increased the temperature sensitivity (Q₁₀) of SOC mineralization in the Vertisol at temperature ranges below 33 °C (i.e., 13–23 and 23–33 °C) and had no significant effect in the Luvisol. A negative correlation was observed between temperature and the Q₁₀ values. Across soils, the Q₁₀ of residue C was lower than SOC suggesting that soil C is more vulnerable to climatic warming. This work demonstrates that the magnitude of SOC priming by wheat residue and Q₁₀ of SOC mineralization varied significantly with soil type (Luvsiol > Vertisol) and incubation conditions (temperature and time). Given the current trend towards increasing atmospheric temperatures, future studies should evaluate temperature effects on the priming of different pools of SOC induced by crop residue in different agro-ecosystems.

22779. 题目: Carbon sequestration capacity of mangrove soils in micro tidal estuaries and lagoons: A case study from Sri Lanka
文章编号: N19040307
期刊: Geoderma
作者: K.A.R.S. Perera, M.D. Amarasinghe
更新时间: 2019-04-03
摘要: Mangroves are supreme agents in building blue carbon pools by capturing atmospheric carbon and storing them in biomass and soil. Anaerobic mangrove soils favour accumulation of partially decomposed organic matter that builds the carbon stocks over time. This study is an attempt to quantify the stock of total organic carbon (TOC) and to determine its spatial as well as vertical distribution in soils of mangrove ecosystems in Sri Lanka. Seven mangrove areas representing the wet, dry and intermediate climatic zones of Sri Lanka were chosen for this purpose. Samples were taken from three depths, (0–15 cm, 16–30 cm and 31–45 cm) of mangrove soils and TOC was determined by dichromate-oxidation method followed by colorimetry. Surface layers of soils (0–15 cm depth) in general contained high amounts of carbon, particularly in mangrove soils of the wet and intermediate climatic zones. In majority of mangrove areas TOC stocks increased with depth and across the water-land gradient. Estimated magnitude of the carbon pools in Sri Lankan mangrove soils ranged from 316.29 to 580.84 Mg ha⁻¹(1 Mg = 1 t = 10³ kg) (total sampling area 13600m²). Mangrove soils of Rekawa lagoon, located in the intermediate climatic zone was found to be the largest soil carbon sink (580.84 Mg ha⁻¹), while that of Batticaloa lagoon in the dry zone, was the smallest (316.29 Mg ha⁻¹). A statistically significant (p < 0.05) relationship was observed between annual rainfall and total organic carbon storage in mangrove soils. The conservative estimate of the magnitude of total carbon pool in soils of all mangrove areas in Sri Lanka that extend over 15,670 ha therefore, is 5623.70 × 10³ Mg. Mangrove soils in Sri Lanka, in their micro-tidal environment, preform a superior carbon sequestration function and therefore deserve better protection.

22780. 题目: Kinetic Models of Vitrinite, Kerogen, and Bitumen Reflectance
文章编号: N19040306
期刊: Organic Geochemistry
作者: Alan K. Burnham
更新时间: 2019-04-03
摘要: Vitrinite reflectance is perhaps the most widely used property to calibrate paleothermal histories, and the most common model for that purpose is Easy%Ro. This paper reviews the origin of Easy%Ro as a simplification of Vitrimat. Weaknesses of the original versions are discussed, as are historical attempts to improve them. New versions of Vitrimat and Easy%Ro are presented that use substantially higher frequency factors and activation energies, and variations of these versions are derived for vitrinite itself and hydrogen-rich macerals and bitumen. The Vitrimat models are based on the original premise that reflectance correlates primarily with H/C ratio and secondarily with O/C ratio. With this approach, the reflectance of different types of organic matter is automatically calculated based on the initial composition of that organic matter. This general approach may also serve as a pathway with appropriate cross-reaction terms to calculate suppression of true vitrinite reflectance matured in oil-prone rocks containing significant concentrations of liptinite.