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25321. 题目: Methane sources and sinks in continental sedimentary systems: New insights from paired clumped isotopologues ¹³CH₃D and ¹²CH₂D₂
文章编号: N18111009
期刊: Geochimica et Cosmochimica Acta
作者: Thomas Giunta, Edward D. Young, Oliver Warr, Issaku Kohl, Jeanine L. Ash, Anna Martini, Scott O.C. Mundle, Douglas Rumble, Ileana Pérez-Rodríguez, Mark Wasley, Douglas E. LaRowe, Alexis Gilbert, Barbara Sherwood Lollar
更新时间: 2018-11-10
摘要: Stable isotope compositions of methane (δ¹³C and δD) and of short-chain alkanes are commonly used to trace the origin and fate of carbon in the continental crust. In continental sedimentary systems, methane is typically produced through thermogenic cracking of organic matter and/or through microbial methanogenesis. However, secondary processes such as mixing, migration or biodegradation can alter the original isotopic and composition of the gas, making the identification and the quantification of primary sources challenging. The recently resolved methane ‘clumped’ isotopologues Δ¹³CH₃D and Δ¹²CH₂D₂ are unique indicators of whether methane is at thermodynamic isotopic equilibrium or not, thereby providing insights into formation temperatures and/or into kinetic processes controlling methane generation processes, including microbial methanogenesis.In this study, we report the first systematic use of methane Δ¹³CH₃D and Δ¹²CH₂D₂ in the context of continental sedimentary basins. We investigated sedimentary formations from the Southwest Ontario and Michigan Basins, where the presence of both microbial and thermogenic methane was previously proposed. Methane from the Silurian strata coexist with highly saline brines, and clumped isotopologues exhibit large offsets from thermodynamic equilibrium, with Δ¹²CH₂D₂ values as low as - 23 ‰. Together with conventional δ¹³C and δD values, the variability in Δ¹³CH₃D and Δ¹²CH₂D₂ to first order reflects a mixing relationship between near-equilibrated thermogenic methane similar to gases from deeper Cambrian and Middle Ordovician units, and a source characterized by a substantial departure from equilibrium that could be associated with microbial methanogenesis. In contrast, methane from the Devonian-age Antrim Shale, associated with less saline porewaters, reveals Δ¹³CH₃D and Δ¹²CH₂D₂ values that are approaching low temperature thermodynamic equilibrium. While microbial methanogenesis remains an important contributor to the methane budget in the Antrim Shale, it is suggested that Anaerobic Oxidation of Methane (AOM) could contribute to reprocessing methane isotopologues, yielding Δ¹³CH₃D and Δ¹²CH₂D₂ signatures approaching thermodynamic equilibrium.

25322. 题目: Ecologic shift and aridification in the northern Tibetan Plateau revealed by leaf wax n-alkane δ²H and δ¹³C records
文章编号: N18111008
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Minghao Wu, Guangsheng Zhuang, Mingqiu Hou, Yunfa Miao
更新时间: 2018-11-10
摘要: Two competing factors, the global cooling and the uplift of Tibetan Plateau, have been proposed to drive the central Asian aridification, but their relative role has seldom been discriminated in paleoclimate and paleoenvironment records. Here, we reconstruct a 14-million-year-long record of paleohydrology and paleoecology in the western Qaidam Basin by applying the compound-specific hydrogen (δ²H) and carbon (δ¹³C) isotope analyses to terrestrial leaf wax long-chain n-alkanes. The δ²H values are low during the interval of 14.6 to 13.0 Ma. Then the δ²H increases from 13.0 to 12.2 Ma and maintains high values from 12.2 to 3.2 Ma with a peak high value of −156.1‰ at 8.0 Ma. After 3.2 Ma, the δ²H values are low and vary larger than 30‰. The δ¹³C values decrease from 14.6 to 13.0 Ma and are low from 13.0 to 3.2 Ma except a high value at 3.8 Ma. Then they decrease slightly after 3.2 Ma. Low δ²H values indicate relatively wet climate between 14.6 and 13.0 Ma. The decreasing δ¹³C values during the same time period support the ecologic shift with the decline of warm component of conifers after the Mid-Miocene Climatic Optimum. High δ²H values since 13.0 Ma are synchronous with the uplift of northern Tibetan Plateau, implying tectonics-driven aridity. Large-amplitude variation in δ²H values since ca. 3.2 Ma seen in East and West Qaidam and lower δ¹³C values reveal the climatic cyclic responses to the Northern Hemisphere Glaciation.

25323. 题目: Adsorption/desorption behavior and mechanisms of sulfadiazine and sulfamethoxazole in agricultural soil systems
文章编号: N18111007
期刊: Soil and Tillage Research
作者: Shuangqing Hu, Yu Zhang, Genxiang Shen, Hongchang Zhang, Zhejun Yuan, Wei Zhang
更新时间: 2018-11-10
摘要: This study focused on the adsorption/desorption behavior and mechanisms of sulfadiazine (SDZ) and sulfamethoxazole (SMX) in two Chinese agricultural soils. The sorption on these two soil systems was investigated through a batch reactor at different initial concentrations (0.5–10 mg L⁻¹), different pH values (4–9) and ionic strengths (0.01–0.5 M). The obtained isotherms were linear within experimental uncertainty. The reversibility of adsorption process was assessed through desorption experiments of SDZ and SMX loaded soil samples. The results demonstrated that sorption was mainly influenced by the physicochemical properties of soil and the adsorbable species. It means that the sorption ability is stronger at higher organic carbon, higher clay fraction, lower pH value and intermediate ionic strength. An apparent decrease in the sorption capacity of SDZ and SMX with increasing pH was primarily attributed to the electrostatic repulsion between anionic species and negatively charged soil particles. Under various ionic strengths, the sorption affinity of SDZ and SMX in two soils revealed that sorption first increased and then decreased with increasing ionic strength. The thermodynamic analyses suggested that the sorption of SDZ and SMX was a spontaneous process. The results from Fourier transform infrared spectroscopy (FTIR) verified that the sorption of these sulfonamides was dominated by hydrogen bonds, electrostatic interactions and π-π interactions. This study contributed substantially to understanding the adsorption/desorption behavior and mechanisms of SDZ and SMX in the environment.

25324. 题目: Prevention of UF membrane fouling in drinking water treatment by addition of H₂O₂ during membrane backwashing
文章编号: N18111006
期刊: Water Research
作者: Wenzheng Yu, Nigel Graham, Ting Liu
更新时间: 2018-11-10
摘要: Although conventional coagulation pre-treatment can mitigate the fouling of ultrafiltration (UF) membrane when treating raw waters, it is insufficient to restrict the development of irreversible fouling and reversible fouling to a low level. In this paper we demonstrate that the intermittent addition of H₂O₂ into the membrane tank during backwash events (after coagulation pre-treatment) successfully prevented the development of any significant membrane fouling. Laboratory-scale tests were undertaken using two membrane systems operated in parallel over 60 days, one serving as a reference coagulation-ultrafiltration (CUF) process, and the other receiving the H₂O₂ (CUF-H₂O₂), with a decreasing dose in three successive phases: 10, 5 and 2 mg/L. The results showed that the addition of H₂O₂ (via a separate dosing tube) during a 1 min backwash process (at 30 min intervals) reduced the growth of bacteria in the membrane tank, and the associated concentrations of soluble microbial products (SMP, including protein and polysaccharide). This resulted in a much reduced cake layer, which contained significantly less high MW organic matter (>50%), such as EPS, thereby improving the interaction between particles in the cake layer and/or particles and the membrane surface. There was also less organic matter, of all MW fractions, adsorbed in the membrane pores of the CUF-H₂O₂ system. The addition of H₂O₂ in the membrane tank appeared to alter the nature of the organic matter with a conversion of hydrophobic to hydrophilic fractions, which induced less organics adsorption within the hydrophobic PVDF membrane pores, and a reduced bonding ability for particles. There was no physico-chemical evidence of any deterioration of the membrane from exposure to H₂O₂, which indicates the feasibility of applying this novel method of fouling control for full-scale UF based water treatment processes.
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25325. 题目: Low concentrations of copper oxide nanoparticles alter microbial community structure and function of sediment biofilms
文章编号: N18111005
期刊: Science of The Total Environment
作者: Lingzhan Miao, Peifang Wang, Jun Hou, Yu Yao, Zhilin Liu, Songqi Liu
更新时间: 2018-11-10
摘要: In this study, we investigated the effects of copper oxide (CuO) NPs on freshwater sediment biofilms in terms of the functional properties and microbial community structure. Biofilms were incubated in microcosms and CuO NPs (1 mg/L uncoated and humic-acid-coated) were exposed with Cu²⁺ (Cu(NO₃)₂) as the positive control. As determined from DO (dissolved oxygen) microelectrodes measurements, a high-DO region emerged inside the biofilms after 5-day exposure to CuO NPs compared with those before NP additions, which suggested CuO NPs inhibit the oxygen respiration activity. These results were consistent with the decreased heterotrophic respiration. CuO NPs significantly altered the bacterial community composition and decreased the abundances of Anaerolineaceae, Acidobacteria, Aminicenantes, and Anaerolinea. Functional analysis from PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States)-predicted metagenomes indicated that bacterial genera depleted by CuO NP treatments were related to carbohydrate and glycan biosynthesis and metabolism, and biosynthesis of other secondary metabolites. These functional profiles combined with the decreased activities of extracellular enzymes, β-glucosidase (GLU) and l-leucine aminopeptidase (LAP), suggested that the introduction of CuO NPs exhibit negative effects on the biogeochemical processes and the cycling of carbon and nitrogen in biofilm systems. Whereas these toxic effects of CuO NPs could be mitigated when the aquatic environment is enriched with natural organic matters such as humic acid.
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25326. 题目: Occurrence and spatial distribution of phthalate esters in sediments of the Bohai and Yellow seas
文章编号: N18111004
期刊: Science of The Total Environment
作者: Lijie Mi, Zhiyong Xie, Zhen Zhao, Mingyu Zhong, Wenying Mi, Ralf Ebinghaus, Jianhui Tang
更新时间: 2018-11-10
摘要: Phthalate esters (PEs) are a class of synthetic chemicals that have been widely used as plasticizers in industrial products and households. The occurrence of PEs in the marine environment has been a concern for many years because of their adverse impacts on marine organisms and human health. In this study, six major PEs, i.e. diethyl phthalate (DEP), di‑isobutyl phthalate (DiBP), di‑n‑butyl phthalate (DnBP), benzylbutyl phthalate (BBP), dicyclohexyl phthalate (DCHP) and di‑(2‑ethylhexyl) phthalate (DEHP), were analyzed in sediment samples collected in the Bohai and Yellow seas. The sum concentrations of the six PEs ranged from 1.4 to 24.6 ng/g and the average was 9.1 ng/g. The highest concentrations of PEs in the sediment samples were those of DEHP with a median concentration of 3.77 ng/g, followed by DiBP (median, 1.60 ng/g), DnBP (0.91 ng/g), DEP (0.32 ng/g), BBP (0.03 ng/g) and DCHP (0.01 ng/g). Generally, concentrations of PEs in the Bohai Sea are higher than those in the Yellow Sea. The varying spatial distributions of the individual PEs can be the result of discharge sources, regional ocean circulation patterns, and mud areas in the Bohai and Yellow seas. Significant positive correlations were found between total organic carbon content and the concentrations of DiBP, DnBP, and DEHP. It is estimated that the inventories of the ∑6PEs were 20.73 tons in the Bohai Sea and 65.87 tons in the Yellow Sea. Both riverine discharge and atmospheric deposition are major input sources for the PE sedimentation, while massive plastic litter and microplastics sinking to the ocean floor can directly release PEs into sediment. This study provides an appropriate data set for the assessment of the risk of PEs to the marine ecosystem.
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25327. 题目: Insights into the phosphate adsorption behavior onto 3D self-assembled cellulose/graphene hybrid nanomaterials embedded with bimetallic hydroxides
文章编号: N18111003
期刊: Science of The Total Environment
作者: Lei Zhang, Zihang Wang, Xing Xu, Cheng Chen, Baoyu Gao, Xiaolong Xiao
更新时间: 2018-11-10
摘要: 3D self-assembled cellulose/graphene hybrids (3D cell/GO hybrids) were used as the host for encapsulating the Zr and La hydroxides, forming the Zr/La-cell/GO hybrids. After phosphate adsorption, the crystallization peaks of LaPO₄·xH₂O in saturated Zr/La-cell/GO hybrids were observed and they were reduced with the increase in pHs. Especially, a low crystallization was observed at pH 10.0 as compared with those at pH 3.0 and 6.0; this also corresponded well to the varied adsorption capacity as a function of pHs. The increased humic acid (HA) amounts (150 mg/L) only resulted in a low capacity loss (16.3%) in phosphate uptake from 25.3 to 21.2 mg/g. A noticeable La leach (2.1 mg/L) was observed at the HA level of 150 mg/L but no Zr leach was detected, and therefore, complexation of La with HA seemed a potential explanation for the increased La leaching. The interference of different coexisting anions on phosphate uptake followed the order as F⁻ > SiO₃²⁻ > HCO₃⁻ > SO₄²⁻ > NO₃⁻ > Cl⁻. Phosphate uptake by Zr/La-cell/GO hybrids was significantly reduced at the co-existing fluoride partially due to the stronger electro-negativity of fluoride to combine with the protonated Zr/La hydroxides. In addition, Ca²⁺ laden on the Zr/La-cell/GO hybrids significantly enhanced the adsorption of phosphate by Zr/La-cell/GG hybrids due to the formation of calcium phosphate precipitation in framework of Zr/La-cell/GG hybrids.
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25328. 题目: Copper and zinc fractionation in soils treated with CuO and ZnO nanoparticles: The effect of soil type and moisture content
文章编号: N18111002
期刊: Science of The Total Environment
作者: Izabela Jośko
更新时间: 2018-11-10
摘要: Increased use of nano-products results in the release of nano-constituents into various environmental media, including soils. The metal components of inorganic nanoparticles are subject to partitioning during the various soil phases. The aim of the study presented here was to estimate Zn and Cu distribution in different soils after treatment with nano-ZnO and nano-CuO (10 mg kg⁻¹) under various moisture conditions (30, 50 and 80% of water holding capacity). Samples were incubated for 24 h, 3 and 24 months. In addition, the effect of the form of Cu (nano-CuO, nano-Cu, bulk-CuO and CuCl₂) on Cu partitioning was estimated. The assessment of metal distribution was made using sequential analysis, which allowed to distinguish five fractions: exchangeable (F1), carbonate (F2), bound with Fe-Mn oxides (F3), bound with organic matter (F4), and residual (F5). The results of the analyses revealed that in the treated and untreated soil the percentage of potentially bioavailable metal fractions (F1, F2) was considerably lower than the total content of fractions considered to be stable (F3, F4, F5). Fractionation of Cu and Zn differed, which could have resulted from different rates of solubility as well as from soil properties and moisture content.
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25329. 题目: A field-deployable surface-enhanced Raman scattering (SERS) method for sensitive analysis of silver nanoparticles in environmental waters
文章编号: N18111001
期刊: Science of The Total Environment
作者: Huiyuan Guo, Leigh C. Hamlet, Lili He, Baoshan Xing
更新时间: 2018-11-10
摘要: The proliferation of silver nanoparticles (AgNPs) in the environment and resultant transport into aquatic systems have raised concerns regarding their potential toxicity to various organisms. These environmental and ecological concerns demand reliable AgNP detection methods which can measure environmentally relevant quantities of AgNPs in real aquatic systems. This study developed a method that couples a rapid vacuum filtration technique with a portable Raman spectrometer to achieve on-site detection of ultra-low levels of AgNPs in typical and complex aquatic systems. To extract and detect AgNPs, aluminum chloride and ferbam were added for AgNP aggregation and labelling, respectively. The AgNP aggregates were filtered through a membrane, and their presence and quantity were determined based upon the surface-enhanced Raman scattering (SERS) peak intensity of ferbam. Under the optimized conditions, the extraction efficiencies are 99 ± 0.001% in ultrapure water and 98 ± 0.025% in marine water for 1 mg/L AgNPs. This method enables simple volume adjustment and improves the consistency of AgNP distribution on the membrane. The performance of the method was evaluated in different environmental waters, including marine water, fresh waters (pond water, river water, and reservoir outlet water) and drinking waters (municipal tap water and well water), with highest signal intensity in marine water and lowest signals in fresh waters. The signal intensity difference was suggested to be caused by the amount of natural organic matter (NOM) in these environmental waters. Using pond water as an example, the interference was minimized by changing the aggregating salt from AlCl₃ to MgCl₂, and AgNPs as low as 5 μg/L were reliably detected with a volume of 100 mL. At the same volume, the developed method was sensitive enough to detect 1 μg/L AgNPs in marine water and also holds promise for assessing the time-dependent transformation of AgNPs.
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25330. 题目: Genetic Structure and Haplotype Pattern of Marine Planktonic Ostracod (Porroecia spinirostris) from South China Sea Based on Mitochondrial COI Gene
文章编号: N18110913
期刊: Ocean Science Journal
作者: Lei Xu, Hong Li, Lianggen Wang, Feiyan Du
更新时间: 2018-11-09
摘要: Ostracods (Crustacea, Ostracoda) are small bivalved crustaceans, contributing to the marine zooplankton community. They are widely distributed and are relatively abundant components of the marine mesozooplankton worldwide, playing an important role in the transport of organic matter to deep layers. By analysing the mitochondrial COI gene, we explored the population genetic structure and haplotype pattern of Porroecia spinirostris which is the dominant ostracod in the South China Sea. We investigated the population genetic structure of ostracods at medium spatial scales in the absence of physical barriers. Our data provides evidence of the importance of both long-distance dispersal as well as genetic isolation in determining the seascape genetic structure of this species. Our data suggest that P.spinirostris can achieve long distance dispersal and specific haplotypes were successful in colonizing habitats from the Xisha to the Nansha area. A total of 36 haplotypes were defined from 85 individuals with most of these haplotypes occurring only once. The dominant haplotype was found in twelve sampling sites. The largest distance between two sampling sites harbouring this haplotype is more than 700 km. Our findings of long distance dispersal in the South China Sea combined with mild genetic differentiation among fifteen sampling sites (average ΦST = 0.167) are in line with a scenario where population genetic structure is strongly impacted by colonization patterns. The seascape genetic structure of P.spinirostris in the South China Sea reflects both the importance of long distance dispersal as well as of reduced levels of gene flow, likely caused by colonization events followed by demographic expansions.

25331. 题目: Geochemical and micropaleontological impacts caused by the 2011 Tohoku-oki tsunami in Matsushima Bay, northeastern Japan
文章编号: N18110912
期刊: Marine Geology
作者: Toshiaki Irizuki, Osamu Fujiwara, Kaoru Yoshioka, Atsushi Suzuki, Yuichiro Tanaka, Masayuki Nagao, Shungo Kawagata, Shigenori Kawano, Osamu Nishimura
更新时间: 2018-11-09
摘要: We present stratigraphic, geochemical (CNS elemental analysis), and micropaleontological (ostracode assemblages) evidence for the 2011 Tohoku-oki tsunami impact in Matsushima Bay, northeastern Japan, and examine the recovery process after the impact to the bay environment using short sediment cores from two different topographic settings at a water depth of approximately 4 m. At both sites, tsunami deposits are composed of two sedimentary layers that recorded the first tsunami run-up and backwash. At the western site near the channel that connects the bay with the Pacific Ocean, the first tsunami wave eroded the bay floor sediments and left the tsunami deposits composed of medium sand rich in shell fragments, but with sparse numbers of meiobenthic ostracodes. By contrast, at the eastern site, which is surrounded by many small islands, the first wave eroded very little of the bay floor sediments and left tsunami deposits consisting of sandy mud, rich in exotic ostracodes, such as phytal species, shallow marine sand dwelling species, and brackish water species. Overlying post-tsunami deposits are composed mainly of organic-rich mud in which organic matter was derived primarily from marine plankton. Ostracode assemblages in the tsunami deposits lack the offshore species that live in water depths >50 m and are dominated by the species from Matsushima Bay and its adjacent nearshore, upper sublittoral areas, and brackish water environments. The distance from deep-water offshore areas to the core sites is too far to transport ostracode valves by tsunami waves.

25332. 题目: Spatial simulation of soil-water content in dry and wet conditions in a hectometer-scale alpine meadow
文章编号: N18110911
期刊: Land Degradation & Development
作者: Xu-Chao Zhu, Rui-Xue Cao, Ming-An Shao
更新时间: 2018-11-09
摘要: Soil‐water content (SWC) is a key factor in restoring degraded vegetation in alpine‐meadow ecosystems, but it has rarely been spatially simulated on a hectometer scale. We simulated SWC for typical dry and wet days in an alpine meadow using multivariate linear regression and autoregressive state‐space equations based on SWC and other soil, terrain and vegetation parameters to evaluate the efficiency of these two methods in dry and wet soil moisture conditions. SWC measured on a typical dry day (SWC‐D) and a wet day (SWC‐W) increased and decreased with depth, respectively and SWC‐D was similar to SWC‐W at a depth of 50 cm. Both SWC‐D and SWC‐W were significantly correlated with soil bulk density (BD), capillary porosity (CP), silt content (Silt), gravel and stone content (GSC), pH and organic carbon density (OCD), and both SWC‐D and SWC‐W were significantly auto‐correlated and cross‐correlated with BD, Silt, GSC, pH and OCD at more than one lag distance. Multivariate linear regression using three variables in both dry and wet conditions had the highest accuracy, and the accuracy was generally higher for dry conditions than it was for wet conditions. The bivariate state‐space model was the most accurate for both dry and wet soil conditions, but the expression variables were totally different, with pH and OCD for dry day and BD and Silt for wet day. The conditions of soil moisture should thus be considered when choosing variables with which to simulate SWC, instead of only considering the relationships between SWC and other variables.

25333. 题目: The use of biochar and crushed mortar in treatment wetlands to enhance the removal of nutrients from sewage
文章编号: N18110910
期刊: Environmental Science and Pollution Research
作者: Tanveer Saeed, Nilufar Yasmin, Guangzhi Sun, Ariful Hasnat
更新时间: 2018-11-09
摘要: An experimental study was carried out using in pilot-scale constructed wetland systems, operated in parallel to treat raw sewage. Each system consisted of a vertical flow (VF) unit that was filled with biochar as the main media, followed by a horizontal flow (HF) unit filled with crushed cement mortar. Hydraulic loading (HL) ranged 340–680 mm/day was applied on the VF wetland units, where high total nitrogen (TN) mass removal rate (20–23 g N/m² d) was obtained, demonstrating that biochar media had a beneficial effect on the degradation of nitrogenous pollutants. Total phosphorus (TP) removal percentage (concentration based) was ≥ 86% in HF wetlands packed with mortar materials. In one system, the flow direction of the sewage was directed by the deployment of downflow pipes and vertical baffles, aiming to facilitate the formation of aerobic and anaerobic zones in the wetland matrices. The effects of such arrangement were analyzed by comparing pollutant removal efficiencies in the two systems. On average, 99, 96, 93, and 86 percentage removals were obtained for ammonia (NH₄-N), TN, biochemical oxygen demand (BOD), and TP, respectively, during the experiments. Biochar and crushed mortar proved to be a highly effective combination as media in subsurface flow constructed wetlands for wastewater treatment.

25334. 题目: Efficiency of sequential UV/H 2 O 2 and biofilm process for the treatment of secondary effluent
文章编号: N18110909
期刊: Environmental Science and Pollution Research
作者: Peng-Fei Yan, Shoujun Yuan, Wei Wang, Zhen-Hu Hu, Yang Mu, Han-Qing Yu
更新时间: 2018-11-09
摘要: In response to the shortage of water resources, multiple processes have been applied to turn wastewater secondary effluent (SE) into potable water. However, trace organic contaminants (TOrCs) and high concentrations of organic matter contained in SE pose a significant challenge to the reclamation. In this manuscript, combined UV-based and biofilm processes were used to treat the SE spiked with ibuprofen (IBU) and clofibric acid (CA). The efficiency of these sequential treatments was characterized in terms of changes in dissolved organic carbon (DOC), absorbance at 254 nm (A₂₅₄), fluorescence excitation-emission matrix (FEEM), the concentration of IBU and CA, and molecular weight of SE. Parallel factor (PARAFAC) was applied as the analysis method for FEEM of the samples and two fluorescent components were successfully identified: humic-like substances (C1) and protein-like matter (C2). Large reductions in A₂₅₄, C1, C2, IBU, and CA were observed during the UV-based processes, especially with the addition of H₂O₂. Nearly 50% of A₂₅₄, 80% of the component C1 were decreased and almost complete removal of the component C2 and TOrCs was achieved by UV/2.0 mM H₂O₂ after 90-min treatment. During the oxidation processes, the formation of lower molecular weight (LMW) compounds was detected, and the biodegradability of the organic matters was greatly increased. Although no significant DOC reduction was obtained in UV-based processes, an obvious further DOC reduction (30~60%) was achieved by biofilm treatment following UV-based processes, especially after UV/H₂O₂ treatments. In the meantime, large amounts of LMW were removed in the biofilm treatment process. This manuscript provides an effective advanced treatment of SE for the removal of DOC and TOrCs, facilitating the wastewater reclamation.

25335. 题目: Stability of Ferrihydrite–Humic Acid Coprecipitates under Iron-Reducing Conditions
文章编号: N18110908
期刊: Environmental Science & Technology
作者: Jacqueline Mejia, Shaomei He, Yu Yang, Matthew Ginder-Vogel, Eric E. Roden
更新时间: 2018-11-09
摘要: Recent studies have suggested the potential for release of iron (hydr)oxide-bound organic carbon (OC) during dissimilatory iron oxide reduction (DIR). However, the stability of iron (hydr)oxide-bound OC in the presence of a natural microbial consortium capable of driving both OC metabolism and DIR has not been resolved. Pure ferrihydrite (Fhy) and Fhy–humic acid coprecipitates (Fhy-HA) were inoculated with a small quantity of freshwater sediment and incubated under anoxic conditions in the presence and absence of H₂ or glucose as electron donors for DIR. H₂ promoted DIR led to release of ca. 1 mM dissolved organic carbon (DOC). However, comparable amounts of DOC were released from both pure Fhy and Fhy-HA, similar to DOC levels in mineral-free, inoculum-only controls. These results suggest that the observed DOC release during H₂-promoted DIR originated from OC contained in the inoculum as opposed to the much larger pool (ca. 38 mM) of OC in the Fhy-HA. Thus, DIR preferentially released sorbed OC with low aromaticity (inoculum OC) versus highly aromatic OC (HA) coprecipitated with iron oxide. Our findings provide new insight into the extent and mechanisms by which DIR is likely to influence aqueous/solid-phase OC partitioning in anoxic soils and sediments.
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25336. 题目: Fern, Dicranopteris linearis, derived phytoliths in soil: morphotypes solubility and content in relation to soil properties
文章编号: N18110907
期刊: European Journal of Soil Science
作者: M. N. Nguyen, A. Meharg, M. Carey, S. Dultz, F. Marone, S. B. Cichy, C. T. Tran, G. H. Le, N. T. Mai, T. T. H. Nguyen
更新时间: 2018-11-09
摘要: Ferns are among the most popular groups of plants in the tropics and subtropics, and their role as carbon sequestrators has been widely recognized. However, there is little understanding of the silicaceous structures (phytoliths) of ferns, rate of phytolith turnover, the consequences for organic matter sequestered in phytoliths and consequences for other soil properties. In the study reported here, high resolution X‐ray tomographic microscopy and chemical characterization were applied to examine the traits of phytoliths of the fern Dicranopteris linearis (Burm.f.) Underw. (D. linearis), with a focus on their dissolution properties and accumulation in northern Vietnamese soils in relation to soil properties. Tomographic images revealed an inter‐embedding structure of silica and organic matter, especially in leaf derived material. We propose that organic matter and silica can preserve each other against decomposition. In batch experiments, there was a relatively small rate of dissolution of phytoliths with dry ashing and subsequent H₂O₂ treatment. Silicon (Si) dissolution for D. linearis phytolith samples was much less than that for rice phytoliths. Despite the fact that the aluminum (Al) content was large in D. linearis leaves, batch dissolution data did not confirm a relation between Al and the slow rate of phytolith dissolution. The soil phytolith content varied from 0.9 to 7.5 g kg^–1 in the topsoil across the mountainous areas in northern Vietnam, whereas it tended to be smaller in the subsoil. The data indicate a relation between phytolith and soil organic matter, clay content, oxalate‐soluble Al and electrical conductivity, suggesting that these soil properties are among the important factors affecting the size of the soil phytolith Si pool.

25337. 题目: Soil properties and distribution in the riparian zone: the effects of fluctuations in water and anthropogenic disturbances
文章编号: N18110906
期刊: European Journal of Soil Science
作者: F. Ye, M. H. Ma, S. J. Wu, Y. Jiang, G. B. Zhu, H. Zhang, Y. Wang
更新时间: 2018-11-09
摘要: China’s Three Gorges Dam has generated a large riparian zone around the reservoir that has changed the natural fluctuation in water level (FWL) and intensity of anthropogenic disturbance (AD, i.e. human activities triggering pollutant input). Knowledge about how riparian soil properties respond to such changes remains limited. The aims of this study were to identify the distribution of soil properties in the riparian zone and to determine which types of factors, local‐scale FWL or regional‐scale AD, have a larger effect on the soil properties. A total of 144 composite soil samples, collected from two riparian areas in four sampling surveys, were investigated. Multivariate regression tree analysis indicated that the variation in soil properties was mainly controlled by FWL (40.1%) compared with the minor role of AD (2.1%). Soil total carbon, total nitrogen and organic matter were mainly affected by AD, whereas FWL had a major influence on soil pH, ammonium and nitrate. Along the elevation gradient (150–175 m), the soil properties were determined mainly by the sampling elevation, accounting for 67.6% of the variation, followed by short‐term (5.6%) and long‐term flooding (3.3%). The 167.5‐m elevation was proposed to be the threshold that divides the riparian zone into two different response zones. Soil below 167.5 m was mainly affected by local‐scale FWL, whereas that above 167.5 m was largely affected by regional‐scale AD. This proposed threshold suggests that riparian soil management around the Three Gorges Reservoir should consider both local‐ and regional‐scale factors and that different approaches and strategies for ecological restoration need to be applied along an elevation gradient.

25338. 题目: Formation kinetics of disinfection byproducts in algal-laden water during chlorination: A new insight into evaluating disinfection formation risk
文章编号: N18110905
期刊: Environmental Pollution
作者: Rui Huang, Zhiqi Liu, Boyin Yan, Jingjing Zhang, Dongmei Liu, Yongpeng Xu, Peng Wang, Fuyi Cui, Zhiquan Liu
更新时间: 2018-11-09
摘要: It is necessary and important to investigate the formation of disinfection byproducts (DBPs) in water treatment systems for the management of disinfection formation risk. In the present study, the formation potential of trichloromethane (TCM) and haloacetic acids in different algal metabolites were compared, and the formation kinetics of these DBPs were investigated. The results indicated that DBP formation potential, the traditional index widely used to evaluate the disinfection formation risk, can represent neither the total precursors of DBPs nor the possible generated amounts of DBPs in drinking water systems. Kinetic analyses showed that the formation of DBPs could be well described by a classical second-order reaction kinetic model and that the actual concentrations of DBPs during chlorination were predictable with the model. The formation of DBPs in drinking water treatment systems was highly dependent on the total precursors of DBPs in water and the formation rate of DBPs with chlorine; the latter is usually underestimated in previous studies. Because of their high reactivity, TCM in hydrophilic extracellular organic matter and trichloroacetic acid in all algal metabolites should be serious considerations in the management of disinfection formation risk.
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25339. 题目: Micrometer scale imaging of sedimentary climate archives – sample preparation for combined elemental and lipid biomarker analysis
文章编号: N18110904
期刊: Organic Geochemistry
作者: Susanne Alfken, Lars Wörmer, Julius S. Lipp, Jenny Wendt, Heidi Taubner, Arndt Schimmelmann, Kai-Uwe Hinrichs
更新时间: 2018-11-09
摘要: Mass spectrometry imaging (MSI) can be used for the µm scale mapping of target molecules on intact sample surfaces. Recently we demonstrated that MSI of non-disturbed sediments can be used for paleoenvironmental studies; using matrix-assisted laser desorption/ionization coupled to Fourier transform-ion cyclotron resonance-mass spectrometry we visualized the spatial distributions of archaeal glycerol dibiphytanyl glycerol tetraether (GDGT) lipids. There is a pressing need for implementing sample preparation procedures that allow exploiting the full potential of sediment MSI. Here we present a suite of sample preparation steps, optimized for the analysis of GDGTs in marine sediments. It considers the crucial requirements for successful MSI and optional combination with elemental imaging via micro X-Ray Fluorescence Spectroscopy (µ-XRF). Preservation of the sediment’s spatial distribution is achieved with freeze-drying and subsequent embedding in a mixture of gelatin and carboxymethyl cellulose. This enables sectioning the sample into sequential slices from 20–500 µm thickness. Thinner sections showed enhanced signal intensity in MSI, but elemental mapping by µ-XRF is more accurate for thicker sections; 100 µm thick slices provide satisfactory results for both analyses and are recommended for congruent elemental and biomarker imaging. When applied to the uppermost ∼5 cm of marine sediment from a Santa Barbara Basin box core, the optimized sample preparation yields reproducible ultra-high-resolution GDGT records from sequential slices, thus demonstrating the robustness of the method. Congruent µ-XRF results aid the establishment of a contextual framework regarding supply of terrigenous and marine detritus as well as the assignment of molecular data to annual layers.

25340. 题目: Clade-dependent size response of conodonts to environmental changes during the late Smithian extinction
文章编号: N18110903
期刊: Earth-Science Reviews
作者: Marc Leu, Hugo Bucher, Nicolas Goudemand
更新时间: 2018-11-09
摘要: In contrast to the benthos whose taxonomic recovery was lagging way behind that of the nekton, highly diverse Smithian conodont and ammonoid faunas were profoundly decimated during the late Smithian, ca. 2 Myr after the Permian-Triassic boundary mass extinction. As body size reduction is a common evolutionary response to heavy environmental stress, we investigate how the size of the P1 elements of different conodont clades responded during the late Smithian crisis based on three sections from the northern Indian Margin. A major and world-wide positive carbon excursion is also a consistent signature of the late Smithian time interval. Where adequate ammonoid biochronological control is lacking (i.e., Kashmir), a new carbonate carbon isotope record provides an independent age proxy for correlations with southern Tibet and the Salt Range. Assuming a positive correlation between the size of P1 elements and body size, we confirm that segminate conodonts underwent a size decrease during the late Smithian. However, segminiplanate conodonts consistently displayed a substantial size increase during the same time interval, thus highlighting clade specific, diverging answers and precluding any simplistic generalization of size responses to the same stress event. Additionally, a moderate but consistent size increase during the early Spathian is documented for both clades, thus obscuring any simple general relation between temperature stress and size among conodonts. Comparison of size time series with the oxygen isotopic composition of conodonts (a proxy for sea-water temperature) suggests that only the size of segminate P1 elements may correlate positively with temperature. Although at a slower pace, the size of segminiplanate P1 elements continued to increase during the early Spathian, when temperature rose again after the late Smithian cooling event. Therefore, temperature alone cannot explain the size variations of segminiplanate conodonts. The late Smithian was also a time of increasing burial of organic matter on continental shelves, but lateral variations of this factor also obscure any relation with the documented size changes. Last but not least, the stratigraphically more comprehensive study in Nammal reveals a segminiplanate gap during the middle Smithian thermal high. The biogeographical expansion of this clade towards the low latitudes during the Griesbachian, the early Smithian, the late Smithian and the early Spathian apparently occurred during the coolest intervals of the Early Triassic, in agreement with their supposed cooler habitat.