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30461. 题目: Combined effects of maize straw biochar and oxalic acid on the dissipation of polycyclic aromatic hydrocarbons and microbial community structures in soil: A mechanistic study
文章编号: N18101704
期刊: Journal of Hazardous Materials
作者: Xiaona Li, Yang Song, Fang Wang, Yongrong Bian, Xin Jiang
更新时间: 2018-10-17
摘要: Whether the rhizodegradation of organic contaminants occurs in biochar- amended soil and its potential mechanisms have rarely been reported. Therefore, a study was conducted to investigate the combined effects of root exudates and biochar on the dissipation of polycyclic aromatic hydrocarbons (PAHs) and on the microbial community structures in soil. As a major component of the root exudates of ryegrass, oxalic acid (OA) significantly enhanced the dissipation of high- and low-ring PAHs in the studied soil with or without maize straw biochar amendment (p < 0.05). However, biochar alone enhanced only the dissipation of high-ring PAHs. The activities of three enzymes (urease, polyphenol oxidase and dehydrogenase) were the highest in soil amended with both maize straw biochar and 0.5 mg kg^-1 of OA. Moreover, soil microbial biomass and the abundances of genera and genes associated with PAH degradation were significantly enhanced with the tandem application of biochar and OA (p < 0.05). These changes led to a synergetic effect of biochar and OA on the shifts in microbial community structures and on the dissipation of PAHs, especially for high-ring PAHs. The results in this study suggested that a combined biochar-rhizosphere approach should be a feasible remediation strategy for PAH-contaminated soil.
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30462. 题目: Quantitative reconstruction of Middle and Late Eocene paleoclimate based on palynological records from the Huadian Basin, northeastern China: Evidence for monsoonal influence on oil shale formation
文章编号: N18101703
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Qing-tao Meng, Angela A. Bruch, Ge Sun, Zhao-jun Liu, Fei Hu, Ping-chang Sun
更新时间: 2018-10-17
摘要: The Eocene was an interval of climate evolution, when the extreme high temperatures of the earliest Cenozoic gave way to a global cooling trend. Fine-grained lacustrine sediments of Eocene age from northeastern China represent an excellent archive to study long-term environmental and climatic changes at high-resolution. The Huadian Basin is a Cenozoic, fault-bounded basin in Jilin Province, northeastern China. Though small in area, it contains numerous oil shale- and coal-bearing layers, which provide an abundant Middle to Late Eocene palynoflora. Eighty-five palynomorph genera and one hundred palynomorph species were identified in the Huadian Formation, allowing to distinguish 4 palynozones. The nearest living relatives of the recovered palynomorph taxa suggest the presence of subtropical evergreen and deciduous broad-leaved forests during deposition of the Huadian Formation.Using the coexistence approach (CA), we calculated seven paleoclimatic parameters, which indicate a subtropical warm and humid climate with a mean annual temperature above 13.6 °C and a mean annual precipitation of at least 887 mm. However, the climate became cooler and drier during the transition from the lower Oil Shale Member to the upper Carbonaceous Shale Member. Palaeoclimatic data from the various Middle and Late Eocene basins of northeastern China (i.e., the Huadian, Fushun, Yilan, Hunchun and Jishu basins) were compared with data from North American and European basins. Middle Eocene climate in the Northern Hemisphere was generally warm and humid, and the mean annual temperature and precipitation in northeastern China were similar to those in North America, though slightly lower than those of Europe. Similar trends in temperature and precipitation on different continents support the existence of a global Mid-Eocene cooling event.This paper is the first systematic study of Middle to Late Eocene seasonality in the Huadian Basin. Our results show an apparent differentiation in both temperature and precipitation between summer and winter, supporting the view that the East Asian Monsoon was established in northeastern China already during the Middle to Late Eocene. This Middle and Late Eocene monsoon was likely driven by the development of Pacific trade winds and an alternating, seasonal high- and low-pressure system over Siberia.The climatic changes observed in our dataset, especially the precipitation changes, appear to have played an important role in controlling oil shale formation in the Huadian Basin. A warmer and more humid climate, with abundant precipitation and high subsidence rates, formed a deeper Huadian depositional lake. High productivity and stable stratification provided the abundant organic matter and favorable preservation conditions necessary for oil shale accumulation.

30463. 题目: Natural and anthropogenic changes in a lake-forest system in Bukovina (Romania) since 1340 AD documented by sedimentary organic geochemistry (C, N and n-alkanes)
文章编号: N18101702
期刊: Quaternary International
作者: Máté Karlik, József Fekete, Marcel Mindrescu, Ionela Grădinaru, Gábor Bozsó, Lóránt Bíró, Zoltán Kern
更新时间: 2018-10-17
摘要: Lake Bolătău-Feredeu is a small (surface: 0.3 ha; catchment area: 31 ha) landslide-dammed lake in Bukovina (Eastern Carpathians, Romania). Elemental concentration, stable isotope composition of carbon and nitrogen, and n-alkane composition of the saturated hydrocarbon fraction of the organic material were analyzed along the sediment profile from Lake Bolătău-Feredeu covering the past ∼700 years. The ranges of δ¹³C values (−30.5 to −26.6‰) and C/N atomic ratios (10.5 and 15.4) placed the organic material of the recent Bolătău-Feredeu sediment between the C3 Land Plants and the lacustrine algae. The n-alkane proxies provide better distinction between organic matter inputs. Detected major shifts in the n-alkane composition and the C and N concentrations along with the stable isotope compositions pointed towards three distinct stages in the environmental history of the lake-catchment system. The proxy information indicate a substantial landscape change characterized by deforestation and an increase in open pastureland with herbaceous vegetation from ∼1820. The C/N, δ¹⁵N, and δ¹³C values showed the highest variability probably linked to a variable lacustrine environment and decreased productivity in the catchment between ∼1640 and 1760. It can be assumed that the extended periods of lake ice cover during the cold decades experienced at the turn of the 17^th-18th centuries resulted in diminished biological productivity both in the lake and its catchment. Finally, afforestation and the decline in lake productivity have been reconstructed for the period of ∼1470–1560.

30464. 题目: Geomorphological changes in the coastal area of Farasan Al-Kabir Island (Saudi Arabia) since mid Holocene based on a multi-proxy approach
文章编号: N18101701
期刊: Quaternary International
作者: Kosmas Pavlopoulos, Olga Koukousioura, Maria Triantaphyllou, Dimitris Vandarakis, Solène Marion de Procé, Vassilia Chondraki, Eric Fouache, Vasilios Kapsimalis
更新时间: 2018-10-17
摘要: The geomorphological evolution of the southeastern coastal area of Farasan Al-Kabir Island (Saudi Arabia) is revealed by the mapping of modern landforms and a multi-proxy and high spatial resolution study including grain size, particulate organic carbon, mineralogy, element geochemistry, benthic foraminifera analysis and radiocarbon dating of a 3.3-m long sediment core. The modern geomorphological features comprise a variety of arid landforms, such as plateau, cliffs and pediments of Pleistocene coral limestones, playa depressions located on plateau surfaces, alluvial fans, butte and sandy beaches. The mid Holocene evolution of the borehole area is resulted from the detailed analysis of five sedimentary units detected along the core Matar-1, and includes three distinct stages: (a) from 5253 ± 223 y cal BP to 3138 ± 223 y cal BP, carbonate coarse-grained material consisting of coral fragments, molluscs, calcareous algae and benthic foraminifera are deposited on a shallow marine fringing reefal platform, which becomes progressively a nearshore backreef (around 3675 ± 215 y cal BP), and later (around 3138 ± 223 y cal BP) a reef ramp; (b) since 3040 ± 220 y cal BP the borehole area obtains the characteristics of a high-energy beach that receives increasing inputs of terrigenous material; (c) subsequently, a supratidal backshore setting is established influenced mostly by terrestrial processes and occasionally by marine processes, as it is indicated by the decreasing and sometimes sporadic presence of benthic foraminifera, and recently, a sedimentary veneer consisting of terrigenous, carbonate and evaporite material is formed by terrestrial, mainly wadi and aeolian, processes.

30465. 题目: Feeding-strategy effect of Pheidole ants on microbial carbon and physicochemical properties in tropical forest soils
文章编号: N18101610
期刊: Applied Soil Ecology
作者: Shaojun Wang, Jihang Li, Zhe Zhang, Minkun Chen, Shaohui Li, Run Cao
更新时间: 2018-10-16
摘要: The research about the effect of ants on soils is generally focused on the aboveground-nesting ant species in temperate soils. Little is known about the potential of belowground nesting ants in regulating soil properties in tropical forests. In this study, three belowground-nesting Pheidole ant species with different feeding habits were surveyed to explore the nesting effects on microbial carbon and physicochemical properties in tropical forest soils. We found that Pheidole ants with high-density nests can induce a pronounced effect on the concentration and vertical variability of microbial carbon and physicochemical properties in soils. Pheidole capellini as a honeydew harvester elevated the levels of soil microbial carbon, soil temperature, total organic carbon, readily oxidizable carbon, and total nitrogen and NO₃⁻, but decreased soil bulk density. Whereas, the highest increase in soil moisture and NH₄⁺ was observed in the nests of P. noda ants (seed predator), and the greatest decrease of dissolved organic nitrogen was in the nests of P. spathifera ants (scavenger). Pheidole capellini ants inputted more materials into the nests, thus they had the greatest modification on the concentration and vertical change in soil properties. We conclude that Pheidole ant species differ in the direction and power of their effect on soil heterogeneity and soil fertility, which may be mainly attributed to different feeding strategies in the tropical forests.

30466. 题目: Surface transport of DOC acts as a trophic link among Mediterranean sub-basins
文章编号: N18101609
期刊: Biogeosciences
作者: Chiara Santinelli, Roberto Iacono, Ernesto Napolitano, and Maurizio Ribera d'Alcalá
更新时间: 2018-10-16
摘要: Characterizing carbon cycling and redistribution in the ocean is an important issue for Mankind, because it may affect key ecosystem services, e.g., support to climate system and food provision. In this paper, using an integrated approach, we explore the impact of the surface circulation on carbon dynamics in the Western Mediterranean Sea, where strong inter-basin differences in primary production do exist. Detailed information on the surface circulation, derived from high-resolution model simulations, is combined with the analysis of accurate, repeated dissolved organic carbon (DOC) data. Our work indicates that the advection of the Atlantic Water acts as a trophic link between the Algerian Basin and the Tyrrhenian Sea, determining a flux of 8.8–37.9×10¹²gDOCyr⁻¹ into the basin. Thus, surface transport of DOC can redistribute chemical energy among regions with different trophic regimes. We hypothesize that this overlooked mechanism plays an important role also in the global ocean.

30467. 题目: Biochar as both electron donor and electron shuttle for the reduction transformation of Cr(VI) during its sorption
文章编号: N18101608
期刊: Environmental Pollution
作者: Xiaoyun Xu, Huang Huang, Yue Zhang, Zibo Xu, Xinde Cao
更新时间: 2018-10-16
摘要: Biochar has been demonstrated to be a promising sorbent and its redox activity can be involved in environmentally relevant redox reactions. In this study, the electron transfer for the reduction transformation of Cr(VI) during its sorption by biochar were evaluated. Biochar derived from peanut shell at 350 °C could effectively remove Cr(VI) from solutions, accompanied by the reduction of Cr(VI) to Cr(III) which was more obvious at the strong acidity (pH = 2), compared to that at the weak acidity (pH = 4). The O-containing functional groups, e.g. C-O and –C=O, were the electron donor moieties of biochar for the Cr(VI) reduction. Biochar could also act as electron shuttle, enhancing Cr(VI) reduction by lactate, especially at the weak acidity (pH = 4) where the reduction rates of Cr(VI) by lactate together with biochar were about 2 and 9 times higher than those by either biochar or lactate alone, respectively. The mediated electrochemical oxidation analysis showed that biochar could increase the electron donating capacity of lactate by up to 23 times at pH = 4. The O-centered radicals, e.g. semiquinone-type radicals, were related with biochar as electron shuttle, which was confirmed by the electron paramagnetic resonance analysis. As a result of electron acceptance from lactate and/or biochar, Cr(VI) was reduced into CrOOH evidenced by X-ray diffraction analysis. Our results indicated that biochar could act as both electron donor and electron shuttle for the reduction of Cr(VI) during the sorption process, making it an alternative for removal of toxic Cr(VI) from wastewaters.
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30468. 题目: Effect of particle size on adsorption of norfloxacin and tetracycline onto suspended particulate matter in lake
文章编号: N18101607
期刊: Environmental Pollution
作者: Yunhe Luo, Chen Jianqiu, Congyanghui Wu, Jingjing Zhang, Jingyang Tang, Jingge Shang, Qianjiahua Liao
更新时间: 2018-10-16
摘要: Aquatic systems are important sinks of antibiotics; however, their final destination has not been completely elucidated. Therefore, we investigated the adsorption behaviors of suspended particulate matter (SPM) in lakes to support the analysis of the migration and transformation of antibiotics in lacustrine environments. SPM was collected from Meiliang Bay (ML) and Gonghu Bay (GH) in Lake Taihu, China, which was sieved into four particle sizes of >300, 150–300, 63–150, and <63 μm for subsequent antibiotic adsorption experiments. All particles exhibited rapid and substantial adsorption of tetracycline and norfloxacin. Most size fractions fit a Langmuir model, indicative of monomolecular adsorption, except the <63-μm fraction, which fit a Freundlich model. Particle size had a substantial influence on antibiotic adsorption; the 63–150-μm fraction had the greatest adsorption capacity, while the >300-μm fraction had the lowest capacity. The influence of particle size on adsorption was mainly related to SPM physicochemical properties, such as cation exchange capacity, surface area, and organic matter content, rather than types of functional groups. Considering the mass ratios, the <63-μm fraction had the greatest contribution to adsorption. Antibiotics adsorbed onto the SPM from ML and GH exhibited different behaviors. The ML SPM settled more readily into sediment, and larger, denser particles were more resistant to resuspension. Conversely, the GH SPM was more likely to be found in the water column, and larger, less-dense particles remained in the water column. These results help improve our understanding of the interactions between SPM and antibiotics in aquatic systems.
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30469. 题目: Increased litterfall contributes to carbon and nitrogen accumulation following cessation of anthropogenic disturbances in degraded forests
文章编号: N18101606
期刊: Forest Ecology and Management
作者: Chun Feng, Zhe Wang, Yan Ma, Songling Fu, Han Y.H. Chen
更新时间: 2018-10-16
摘要: Litterfall production constitutes a significant component of net primary production and is a fundamental process in the global carbon and nutrient cycles of terrestrial ecosystems. Recent studies have demonstrated that the cessation of anthropogenic disturbances including selective harvesting, fuelwood collection, and grazing in degraded forests has led to increased forest cover and soil carbon and nitrogen. Despite the importance of litterfall in terrestrial ecosystems, the dynamics of litterfall production and its contribution to soil carbon and nitrogen following the cessation of anthropogenic disturbances in degraded forests remain poorly understood. We used a chronosequence to examine the litterfall dynamics since the cessation of anthropogenic disturbances in the subtropical forests of Eastern China. We found that annual litterfall production increased significantly from 2.5 Mg ha⁻¹ year⁻¹ in stands with recurring disturbances to 4.5 Mg ha⁻¹ year⁻¹ in stands after 31 years of cessation of disturbances, i.e., approximately 80% increase in litterfall production. The increased litterfall production resulted from increasing shrub cover and stand basal area and canopy succession following restoration. The increase in litterfall production contributed to the increased contents and stocks of soil organic matter, carbon, and nitrogen, which increased in the topsoil (0–10 cm) by 200%, 30%, and 150%, respectively, after 31 years of restoration. Our results show evidence for increased annual litterfall production due to the increased stand basal area and shrub cover and canopy succession from pioneer to late-successional species following the cessation of anthropogenic disturbances in the degraded forests. Our results suggest that the increased litterfall production contributed strongly to the accumulation of organic matter, carbon, and nitrogen in the soil following the cessation of anthropogenic disturbances.

30470. 题目: Transformation and stabilization of straw residue carbon in soil affected by soil types, maize straw addition and fertilized levels of soil
文章编号: N18101605
期刊: Geoderma
作者: Xiangru Xu, Tingting An, Jiuming Zhang, Zhuhe Sun, Sean Schaeffer, Jingkuan Wang
更新时间: 2018-10-16
摘要: Soil organic carbon (SOC) sequestration is influenced by incorporation of maize straw and application of fertilizers, in intensive agricultural regions. However, there is a limited understanding of the transformation and stabilization of the newly added carbon (C) in soils applied with different amounts of straw residue. The aim of this study was to quantify the relationship between straw C input and SOC sequestration across soil types. We applied ¹³C-labeled maize straw (at amounts of 0 g, 1 g, 3 g, 5 g, 10 g per 100 g dried soil), combined with an in-situ carborundum tube method, in fertilized and non-fertilized Phaeozem and Luvisol soils at experimental sites in Northeast China. Over a period of 360 days, we found that the added amounts of maize straw, and fertilization, affected the residual rates, distribution and stabilization of extraneous new C. Fertilized treatments resulted in lower residual rates of maize straw at the end of the experimental period compared with non-fertilized treatments. We observed that the increased SOC from maize straw amendment (1.08 g C kg⁻¹, the average for all treatments) could not compensate for the loss of native SOC (2.49 g C kg⁻¹ soil, the average for all treatments) with 1 × C maize straw input. However, 5 × C and 10 × C straw addition were enough to offset the native SOC loss. An increase in maize straw incorporation with non-fertilized treatments caused the largest increase in new SOC formation which was highest (84.5%) for 10 × C maize straw input at the end of 360 days incubation at the Luvisol site. With increasing C input, turnover rate was observed to increase from 0.06 (1 × C) to 5.07 year⁻¹ (10 × C), and the C turnover in each level of maize straw addition decreased with incubation time. These results demonstrate that soil type, fertilizer application, and a threshold amount of maize straw input are needed to drive net SOC sequestration.

30471. 题目: The impact of nanoscale zero-valent iron particles on soil microbial communities is soil dependent
文章编号: N18101604
期刊: Journal of Hazardous Materials
作者: María T. Gómez-Sagasti, Lur Epelde, Mikel Anza, Julen Urra, Itziar Alkorta, Carlos Garbisu
更新时间: 2018-10-16
摘要: The application of nanoscale zero-valent iron particles (nZVI) for the remediation of contaminated sites is very promising. However, information concerning the ecotoxicity of nZVI on soil microbial communities and, hence, soil quality, is still scarce. We carried out a three-month experiment to evaluate the impact of the application of different concentrations of nZVI (from 1 to 20 mg g DW soil^-1) on soil microbial properties in a clay-loam versus a sandy-loam soil. Data on microbial biomass (total bacteria and fungi by qPCR, microbial biomass carbon), activity (β-glucosidase, arylsulphatase and urease activities), and functional (Biolog Ecoplates^TM) and structural (ARISA, 16S rRNA amplicon sequencing) diversity evidenced that the sandy-loam soil was more vulnerable to the presence of nZVI than the clay-loam soil. In the sandy-loam soil, arylsulphatase activity and bacterial abundance, richness and diversity were susceptible to the presence of nZVI. The high content of clay and organic matter present in the clay-loam soil may explain the observed negligible effects of nZVI on soil microbial properties. It was concluded that the impact of nZVI on soil microbial communities and, hence, soil quality, is soil dependent.
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30472. 题目: Large-river dominated black carbon flux and budget: A case study of the estuarine-inner shelf of East China Sea, China
文章编号: N18101603
期刊: Science of The Total Environment
作者: Yin Fang, Yingjun Chen, Limin Hu, Chongguo Tian, Yongming Luo, Jun Li, Gan Zhang, Mei Zheng, Tian Lin
更新时间: 2018-10-16
摘要: Mobilization of terrestrial-derived and recalcitrant black carbon (BC), including char and soot, from land to ocean exerts a significant influence on the global carbon cycle. This study elaborated the occurrence and spatial distributions of BC, char, and soot concentrations, as well as their burial fluxes, in the estuarine-inner shelf surface sediments of the East China Sea (ECS), an epicontinental sea adjacent to Chinese high-intensity BC emission source regions. Using a combination of BC measurements in the Yangtze River water and coastal ECS aerosol samples, a preliminary BC budget was concurrently constrained. The spatial distribution of char concentrations resembled largely that of BC, but differed significantly from that of soot, indicating that char and soot exhibited different geochemical behaviors. In contrast to concentrations, BC, char, and soot burial fluxes exhibited highly consistent spatial patterns, and all declined as the distance from the coastline increased. For the coastal ECS, riverine discharge dominated (~92%) the total BC input, with the Yangtze River alone accounting for as high as ~72%. The area-integrated sedimentary BC sink flux (630 ± 728 Gg/yr) in the coastal ECS was equivalent to the total BC influx (670 ± 153 Gg/yr), which coincided well with the regional sediment budget. This suggested that the terrestrial-derived and recalcitrant BC could be regarded as an alternative geochemical proxy for tracing the sediment source-to-sink processes in this region. Comparisons between BC and co-generated polycyclic aromatic hydrocarbons (PAHs) budgets in the coastal ECS revealed similarities in their input pathways, but dramatic differences in their ultimate fates. Despite these, the ECS estuarine-inner shelf could serve as a major sink of these terrestrial-based materials in the global ocean.
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30473. 题目: Biochar, soil and land-use interactions that reduce nitrate leaching and N₂O emissions: A meta-analysis
文章编号: N18101602
期刊: Science of The Total Environment
作者: Nils Borchard, Michael Schirrmann, Maria Luz Cayuela, Claudia Kammann, Nicole Wrage-Mönnig, Jose M. Estavillo, Teresa Fuertes-Mendizábal, Gilbert Sigua, Kurt Spokas, James A. Ippolito, Jeff Novak
更新时间: 2018-10-16
摘要: Biochar can reduce both nitrous oxide (N₂O) emissions and nitrate (NO₃⁻) leaching, but refining biochar's use for estimating these types of losses remains elusive. For example, biochar properties such as ash content and labile organic compounds may induce transient effects that alter N-based losses. Thus, the aim of this meta-analysis was to assess interactions between biochar-induced effects on N₂O emissions and NO₃⁻ retention, regarding the duration of experiments as well as soil and land use properties. Data were compiled from 88 peer-reviewed publications resulting in 608 observations up to May 2016 and corresponding response ratios were used to perform a random effects meta-analysis, testing biochar's impact on cumulative N₂O emissions, soil NO₃⁻ concentrations and leaching in temperate, semi-arid, sub-tropical, and tropical climate. The overall N₂O emissions reduction was 38%, but N₂O emission reductions tended to be negligible after one year. Overall, soil NO₃⁻ concentrations remained unaffected while NO₃⁻ leaching was reduced by 13% with biochar; greater leaching reductions (>26%) occurred over longer experimental times (i.e. >30 days). Biochar had the strongest N₂O-emission reducing effect in paddy soils (Anthrosols) and sandy soils (Arenosols). The use of biochar reduced both N₂O emissions and NO₃⁻ leaching in arable farming and horticulture, but it did not affect these losses in grasslands and perennial crops. In conclusion, the time-dependent impact on N₂O emissions and NO₃⁻ leaching is a crucial factor that needs to be considered in order to develop and test resilient and sustainable biochar-based N loss mitigation strategies. Our results provide a valuable starting point for future biochar-based N loss mitigation studies.
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30474. 题目: Regenerative stormwater conveyance (RSC) for reducing nutrients in urban stormwater runoff depends upon carbon quantity and quality
文章编号: N18101601
期刊: Science of The Total Environment
作者: Shuiwang Duan, Paul M. Mayer, Sujay S. Kaushal, Barret M. Wessel, Thomas Johnson
更新时间: 2018-10-16
摘要: Regenerative stormwater conveyance (RSC), a relatively new stormwater management approach, is extensively implemented throughout the mid-Atlantic for nutrient control, but little is known of its pollutant reduction capabilities and controlling factors. This study examined effects of organic carbon (C) quantity and quality on stream water quality and nutrient retention at two RSCs near Annapolis, Maryland, USA by comparing longitudinal changes in water quality at paired restored and unrestored stream reaches, and conducting lab experiments simulating RSC processes. Results showed that RSCs consistently had lower dissolved oxygen saturation (DO%) and pH relative to nearby unrestored streams, probably due to release of labile dissolved organic carbon (DOC). At one RSC, with high nitrate (NO₃⁻) inputs, retention of N (16–37%) and release of DOC (18–54%) were observed with the highest retention of N during summer, and the rates of N retention and DOC release were larger than that of the adjacent unrestored tributary (N: 5–8%, DOC: <18%). At another RSC site with lower NO₃⁻ concentrations, N retention and DOC release were not apparent. Mesocosm experiments showed that NO₃⁻ retention varies with organic C quantity and quality depending on incubating temperature; retention of total N did not increase with organic C due to release of other N species (e.g., organic N). Lab mesocosms showed an increase in the release of soluble reactive phosphorus (SRP) with increasing organic C quantity and quality. However, field measurements did not show any evidence of SRP release at RSCs. The changes in SRP concentrations in streams seemed to be a function of iron levels and leaf litter inputs, but control factors for SRP warrant further investigation. This study suggests that RSC as a restoration approach may be effective for reducing N depending upon C quantity and quality as well as water temperature and N levels.
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30475. 题目: Mineralization of plant residues and native soil carbon as affected by soil fertility and residue type
文章编号: N18101509
期刊: Journal of Soils and Sediments
作者: Yingde Xu, Fan Ding, Xiaodan Gao, Yang Wang, Ming Li, Jingkuan Wang
更新时间: 2018-10-15
摘要: Purpose: Crop residue return is an effective and low-cost agricultural approach for soil organic carbon (SOC) sequestration. Yet, it is largely unknown to what extent the soil fertility and residue type affect the mineralization of maize (Zea mays L.) residue carbon (C) and the decomposition of native SOC. Therefore, a better understanding of the mineralization of C derived from residues and its priming on native SOC is crucial to accurate assessment of the benefits of crop residue returning in agricultural systems. Materials and methods: A 360-day laboratory incubation experiment was carried out with a Cambisol of low and high fertilities amended with three types of ¹³C-labeled maize residues (root, stem, leaf). The abundance of ¹³C (δ¹³C) in the soil samples was measured during different incubation stages. Results and discussion: The results showed that the total mineralization of residue C was significantly higher in the low fertility soil than in the high fertility soil, but there were no significant differences among residue types. For the high fertility soil, all the residue types induced a negative priming on native SOC mineralization during the early incubation stage, but a significant total positive priming by the end of incubation, whereas for the low fertility soil, there was no significant effect of residue return on SOC mineralization. The accumulated priming by the end of incubation did not vary across residue types. Moreover, the sum of mineralization of residue C and native SOC in the high fertility soil was 1.4 times as large as that in the low fertility soil. Conclusions: We conclude that mineralization of crop residue C and native SOC is affected by soil fertility rather than residue type.

30476. 题目: Crude oil as ore fluids: An experimental in-situ XAS study of gold partitioning between brine and organic fluid from 25 to 250 °C
文章编号: N18101508
期刊: Geochimica et Cosmochimica Acta
作者: Lars-S. Crede, Weihua Liu, Katy A. Evans, Kirsten U. Rempel, Denis Testemale, Joël Brugger
更新时间: 2018-10-15
摘要: Organic matter can be associated with mineralization in hydrothermal ore deposits. One hypothesis is that this organic matter represents remnants of organic fluids (crude oils) that were competing with aqueous fluids for metal transport and contributed to metal endowment. We investigated the transport of gold (Au) in model oil compounds (S-free n-dodecane, CH₃(CH₂)₁₀CH₃, DD; and S-bearing 1-dodecanethiol, CH₃(CH₂)₁₀CH₂SH; DDT) from 25 °C to 250 °C using in-situ synchrotron X-ray absorption spectroscopy (XAS) experiments to determine the speciation and the structural properties of gold complexes in the aqueous- and oil-based fluids. For most experiments, DD or DDT were in contact with Au-bearing acidified water, or acidified water plus 10 wt% NaCl (pH_25˚C=1.85 in both cases). Gold rapidly partitioned from the aqueous phase into DD and DDT. Below 125 °C, Au(III)Cl is dominant in the DD and the adjacent water with a refined coordination number (CN) of chloride of 4.0(3) and an Au-Cl bond length of 2.28 Å, consistent with the tetrachloroaurate complex (AuCl₄^-) being stable in both the aqueous and organic phases. In contrast, Au(III) is rapidly reduced in the presence of DDT and an Au(I) complex dominates in both water and adjacent DDT with a CN of sulfur ∼2.0, suggesting a [RS-Au-SR]^- (RS = DDT with deprotonated thiol group) complex with Au-S bond lengths ranging from 2.29(1) Å to 2.31(3) Å. In an open system of DDT in contact with water, of which the water and DDT were analyzed separately, AuCl₄^- was dominant in the water phase, and Au(RS)₂^- dominant in DDT, possibly due to different equilibration kinetics in the beaker and glassy carbon tube.Since sulfur and organothiol compounds are ubiquitous and abundant components in natural oils, this study demonstrates the potential of natural oils to scavenge and enrich gold from co-existing gold-bearing brines. In particular, Au(I) organothiol complexes may contribute to transport in low-temperature (<125 °C) ore fluids such as those in basinal environments – in both hydrothermal fluids and oils. At temperatures ≥ 125 °C, gold was reduced to metallic gold in all experiments, suggesting that organo-stabilized nanoparticles may be the major form of gold to be scavenged, concentrated or transported in crude oils at these conditions. The results imply that brine-oil interactions may enrich Au in oils, and that oils may be an effective ore fluid in sedimentary environments.

30477. 题目: Removal of selected pharmaceuticals in an ultrafiltration-activated biochar hybrid system
文章编号: N18101507
期刊: Journal of Membrane Science
作者: Sewoon Kim, Chang Min Park, Am Jang, Min Jang, Arturo J. Hernández-Maldonado, Miao Yu, Jiyong Heo, Yeomin Yoon
更新时间: 2018-10-15
摘要: In this study, selected target pharmaceuticals (PhACs) including ibuprofen (IBP), 17 α-ethinyl estradiol (EE2), and carbamazepine (CBM) were removed by an ultrafiltration-activated biochar hybrid system (UF-ABC). Based on characteristic analysis, ABC, a by-product of combustion of waste, is a promising alternative to commercially available powdered activated carbon (PAC) due to its enhanced aromatization and porous properties. Three different systems, including UF only and UF-ABC with/without humic acid (HA) were evaluated. The average retention rate of target PhACs within the UF-ABC system (without HA: 45.2%, and with HA: 34.4%) was much higher than that of the UF only (15.4%), suggesting that hydrophobic adsorption by ABC was the dominant mechanism. In addition, although fouling is expected in UF-ABC due to the presence of ABC, the flux decline of UF-ABC showed similar flux behavior to that of the UF only system. The UF-ABC was compared to UF-PAC with respect to retention rate and permeate flux. The average retention rate for the target PhACs was slightly higher in UF-PAC (46.6%) than in UF-ABC (41.4%) for the target PhACs. However, UF-ABC was considered to be a good alternative system because the normalized flux of UF-ABC (0.85 and 0.77) was superior to UF-PAC (0.76 and 0.70) in the absence/presence of HA, respectively. Consequently, UF-ABC was shown to be a suitable alternative to UF-PAC with respect to both retention and fouling reduction.

30478. 题目: High-resolution reconstruction of sedimentary organic matter variability during the Holocene in the mud area of the Yellow Sea using multiple organic geochemical proxies
文章编号: N18101506
期刊: Quaternary International
作者: Xiuning Wu, Lei Xing, Yiqing Jiang, Xiaodong Zhang, Rong Xiang, Liping Zhou
更新时间: 2018-10-15
摘要: As a result of terrestrial input and local circulation, an area containing continuously deposited mud with abundant organic matter (OM) has formed in the Yellow Sea (YS) off the Shandong Peninsula, China, during the Holocene. The understanding of temporal variations in sedimentary organic matter (SOM) from this mud area helps to evaluate the influences of Yellow River discharge and marine productivity on the burial of organic matter in the YS. In this study, multiple organic geochemical proxies were used to reconstruct Holocene changes in SOM in a sediment core (A02C) recovered from the mud area of the YS. Higher total organic carbon (TOC) and biomarker contents during the early Holocene relative to the middle and late Holocene are attributed to sea-level fluctuations. The δ¹³C values of TOC (δ¹³C_TOC) range from −21.8‰ to −23.5‰, becoming more positive from the bottom to the top of the core. TMBR' (terrestrial and marine biomarker ratio) values vary from 0.43 to 0.80, with a decreasing trend during the Holocene. The decrease in TOM contribution was related to elevated sea-level, shifting of the mouth of the Yellow River, and weakening of the East Asian Winter Monsoon (EAWM) during the Holocene. A mixing model with three end-members, based on δ¹³C_TOC and TMBR', reveals that the contribution of soil OM (average 42%) is higher than that of plant OM (average 17%). Simultaneous decreases in the plant OM fraction and the marine OM fraction occurred around 10.3, 8.2, 5.9, 4.2, and 2.8 kyr BP, corresponding to drift-ice events in the North Atlantic. Spectral analyses also reveal that all three OM fractions exhibit 1015-year periodicity and that the soil and plant OM fractions display 1420-year periodicity, consistent with the 1000-year cycle of solar activity and the 1500-year cycle of the Kuroshio Current (KC), respectively.

30479. 题目: Organic matter characteristics in yedoma and thermokarst deposits on Baldwin Peninsula, west Alaska
文章编号: N18101505
期刊: Biogeosciences
作者: Loeka L. Jongejans, Jens Strauss, Josefine Lenz, Francien Peterse, Kai Mangelsdorf, Matthias Fuchs, and Guido Grosse
更新时间: 2018-10-15
摘要: As Arctic warming continues and permafrost thaws, more soil and sedimentary organic matter (OM) will be decomposed in northern high latitudes. Still, uncertainties remain in the quality of the OM and the size of the organic carbon (OC) pools stored in different deposit types of permafrost landscapes. This study presents OM data from deep permafrost and lake deposits on the Baldwin Peninsula which is located in the southern portion of the continuous permafrost zone in west Alaska. Sediment samples from yedoma and drained thermokarst lake basin (DTLB) deposits as well as thermokarst lake sediments were analyzed for cryostratigraphical and biogeochemical parameters and their lipid biomarker composition to identify the belowground OC pool size and OM quality of ice-rich permafrost on the Baldwin Peninsula. We provide the first detailed characterization of yedoma deposits on Baldwin Peninsula. We show that three-quarters of soil OC in the frozen deposits of the study region (total of 68Mt) is stored in DTLB deposits (52Mt) and one-quarter in the frozen yedoma deposits (16Mt). The lake sediments contain a relatively small OC pool (4Mt), but have the highest volumetric OC content (93kgm⁻³) compared to the DTLB (35kgm⁻³) and yedoma deposits (8kgm⁻³), largely due to differences in the ground ice content. The biomarker analysis indicates that the OM in both yedoma and DTLB deposits is mainly of terrestrial origin. Nevertheless, the relatively high carbon preference index of plant leaf waxes in combination with a lack of a degradation trend with depth in the yedoma deposits indicates that OM stored in yedoma is less degraded than that stored in DTLB deposits. This suggests that OM in yedoma has a higher potential for decomposition upon thaw, despite the relatively small size of this pool. These findings show that the use of lipid biomarker analysis is valuable in the assessment of the potential future greenhouse gas emissions from thawing permafrost, especially because this area, close to the discontinuous permafrost boundary, is projected to thaw substantially within the 21st century.
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30480. 题目: In situ production of core and intact bacterial and archaeal tetraether lipids in groundwater
文章编号: N18101504
期刊: Organic Geochemistry
作者: Su Ding, Bernd Kohlhepp, Susan Trumbore, Kirsten Küsel, Kai-Uwe Totsche, Georg Pohnert, Gerd Gleixner, Valérie F. Schwab
更新时间: 2018-10-15
摘要: Groundwater ecosystems host diverse and complex microbial communities that play important roles in the biogeochemical processing of organic matter and in the maintenance of drinking water quality. Here we investigated the microbial community in suspended particulate matter (SPM) of biogeochemically distinct groundwaters (Hainich Critical Zone Exploratory) by analyzing branched and isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs) from bacteria and archaea, respectively. The contributions of those lipids derived from dead and living organisms were determined by analyses of the core lipid distributions of core and intact polar GDGTs. We compared the groundwater GDGT distributions to the ones from soils of potential recharge areas and with archaeal 16S rRNA-gene based community reconstructions to estimate their origin in these terrestrial subsurface environments and thus their potential use for evaluating soil inputs into groundwater. In soils, the relative abundance of intact polar branched GDGTs (brGDGTs) was lower than that of isoprenoid GDGTs (isoGDGTs; 2% vs 5% of total GDGTs), while the opposite trend (71% vs 22% of total GDGTs) was observed in the core lipid pools. This supports previous observations that soil brGDGT-producing bacteria might be more active and thus have higher regeneration rates than the isoGDGT-producing archaea. We found similar trends in the groundwater that might indicate higher activity (i.e., cell division) of brGDGT-producing bacteria than of isoGDGT-producing archaea. The higher relative abundance of the hexamethylated brGDGT in the groundwater SPM (mean 65 ± 9%, n = 5) than in soils (mean 16 ± 7%, n = 22) indicated an in situ origin of brGDGT-producing bacteria. Higher contributions of penta- and tetra-methylated brGDGTs, which suggested some inputs from soil bacteria, was only detected in two out of seven groundwater samples. The strong correlation between core and intact polar isoGDGTs (R² = 0.99, n = 7) in groundwater SPM indicated low disturbance (e.g., surface inputs) and suggested indigenous archaeal communities in the groundwater. This was supported by the results from a previous 16S rRNA-gene study that detected distinct archaeal groups in soils and groundwater. This first GDGT study in groundwater demonstrated that even dynamic karstic subsurface environments host an indigenous bacterial and archaeal community that is adapted to the living conditions. Furthermore, fast recharge events are likely detectable using tetraether lipids from the soil microbial community.