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23581. 题目: Surface nano-engineered wheat straw for portable and adjustable water purification
文章编号: N18112807
期刊: Science of The Total Environment
作者: Ting Li, Fang Fang, Yu Yang, Wanji Shen, Weiwei Bao, Tianran Zhang, Fanrong Ai, Xingwei Ding, Hongbo Xin, Xiaolei Wang
更新时间: 2018-11-28
摘要: Wheat straw (WS), as a cheap and abundant agricultural waste, is usually burned directly in farmland and causes severe air pollution. Therefore, biochar derived from waste WS is prepared and modified by nanoscaled zinc oxide through a facile in-situ surface-modification process. For ease of use, a 3D printed finger-sized unit (FSU) loaded with the above as-prepared WS is designed and implemented. Each unit weighs only 4 g, and could simultaneously reduce three major water contaminants: bacteria, organic dyes, and heavy metal ions. Moreover, it is interesting to note that fresh wheat straw is a flexible material and has excellent electrical conductivity after carbonization. These two properties (flexibility and conductivity) could further adjust water purification performance. The subsequent cellular and animal tests confirmed the biosafety of the water purified with FSU alone.
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23582. 题目: Tracking the historical sewage input in South American subtropical estuarine systems based on faecal sterols and bulk organic matter stable isotopes (δ¹³C and δ¹⁵N)
文章编号: N18112806
期刊: Science of The Total Environment
作者: Ana Caroline Cabral, Marines Maria Wilhelm, Rubens C.L. Figueira, César C. Martins
更新时间: 2018-11-28
摘要: Faecal sterols and stable isotopes (δ¹³C and δ¹⁵N) from bulk organic matter (OM) were analysed in three sedimentary cores collected in two subtropical bays located in the South Atlantic to evaluate historical trends in the sewage input and to track possible changes in the bulk isotopic composition of OM in recent decades. The values of δ¹³C and δ¹⁵N ranged from −27.4 to −25.0‰ and from 0.5 to 3.9‰, respectively, without a clear trend in the variation over the whole period covered by sediment cores and with no conclusive interpretation of a specific range value typically related to the sewage input for these areas. The maximum coprostanol concentration was 0.19 μg g⁻¹ in the upper 4 cm of one core, which was not considered contaminated by evaluation of the sterols diagnostic ratios. Even at low levels, the coprostanol concentrations followed variations in urban and economical regional development. Baseline values for faecal sterols (in average between 0.03 and 0.05 μg g⁻¹), which may represent a previous non-impacted environment scenarios, were calculated for use in comparative perspectives for future evaluations of the sewage input and contamination.
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23583. 题目: An effective method for reconstructing the historical change in anthropogenic contribution to sedimentary organic matters in rivers
文章编号: N18112805
期刊: Science of The Total Environment
作者: Shanshan Wang, Guijian Liu, Jiamei Zhang, Li Zhou, Paul K.S. Lam
更新时间: 2018-11-28
摘要: Surface water quality has been greatly affected by anthropogenic activities around the world in the past decades. Scientists and policymakers should pay close attention to quantify historical change in human impacts on aquatic environment. An effective method for reconstructing the historical input of anthropogenic organic matters in aquatic environment is urgently required. Here, five sediment cores from the Huaihe River were analyzed for n-alkanes (C₈–C₄₀) and isoprenoid alkanes (pristane and phytane) using gas chromatography–mass spectrometry (GC–MS). Sixty years (1955–2014) sedimentary history of n-alkanes was reconstructed using ²¹⁰Pb method. The evaluation of wax n-alkanes percentage (WNA) indicated that the terrestrial higher plant input was predominant in most samples. The main anthropogenic sources were the petroleum hydrocarbon, fossil fuel combustion and the discharge of industrial wastewater and domestic sewage. The results of principal component analysis-multiple linear regression (PCA-MLR) indicated that the respective contributions of anthropogenic and biogenic sources to sedimentary organic matters were 47.8% and 48.1% in the Huaihe River. Furthermore, the anthropogenic contribution displayed a decrease trend from 1991 to 2014, which probably attributed to the effective pollution control measures taken by the local government. However, the anthropogenic contribution was still considerable during this period. Thus, the government should pay attention to organic pollution control in the Huaihe River sediments continuously. In summary, this study provides an effective method for reconstructing the historical change in anthropogenic contribution to sedimentary organic matters in rivers, which can probably be applied to other aquatic environment around the world.
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23584. 题目: Influence of pyrolysis temperature and feedstock on carbon fractions of biochar produced from pyrolysis of rice straw, pine wood, pig manure and sewage sludge
文章编号: N18112804
期刊: Chemosphere
作者: Siye Wei, Mengbo Zhu, Xingjun Fan, Jianzhong Song, Ping'an Peng, Kaiming Li, Wanglu Jia, Haiyan Song
更新时间: 2018-11-28
摘要: In this study, the influences of feedstock and pyrolysis temperature on carbon fractions of biochar were investigated. Four types of organic wastes (rice straw (RS), pine wood (PW), pig manure (PM) and sewage sludge (SS)) were pyrolyzed at different temperatures (300 °C, 400 °C, 500 °C, 600 °C and 700 °C). Biochar produced at low temperature exhibited high yields, high dissolved organic carbon (DOC) content and unstable organic carbon content. In contrast, biochar formed at high temperature showed high C content and C stability with a low O/C and H/C ratios. In addition, the biochar pyrolyzed from PW contained the lowest DOC of the four biochar types. The properties of DOC fractions (F1, F2 and F3) released from biochar differed depending on feedstock, pyrolysis temperatures, and extraction procedures. The highest specific ultraviolet absorbance at 254 nm of the F1 and F2 fractions were observed for RS biochar, suggesting that more aromatic organic matter was present in sequentially extracted fractions of RS biochar than in extracts from the other biochars. In addition, the hot water extracts (F2) mostly showed higher aromaticity than cold water extracts (F1). The stability of biochars was greatly enhanced at pyrolysis temperatures >500 °C. If the biochars produced in this study were to be used for carbon sequestration in soil, the first priority should be PW, followed in order by RS and PM.

23585. 题目: Adsorption behaviour and mechanisms of cadmium and nickel on rice straw biochars in single- and binary-metal systems
文章编号: N18112803
期刊: Chemosphere
作者: Yiyi Deng, Shuang Huang, David A. Laird, Xiugui Wang, Zhuowen Meng
更新时间: 2018-11-28
摘要: Adsorption mechanisms and competition between Cd²⁺ and Ni²⁺ for adsorption by rice straw biochars prepared at 400 °C (RB400) and 700 °C (RB700) were investigated in this study. Based on the Langmuir model, the maximum adsorption capacities (mg g⁻¹) of Cd²⁺ and Ni²⁺ on RB400 and RB700 were in the order of Cd²⁺ (37.24 and 65.40) > Ni²⁺ (27.31 and 54.60) in the single-metal adsorption isotherms and Ni²⁺ (25.20 and 32.28) > Cd²⁺ (24.22 and 26.78) in the binary-metal adsorption isotherms. Cd²⁺ competed with Ni²⁺ for binding sites at initial metal concentrations >10 mg L⁻¹ for RB400 and > 20 mg L⁻¹ for RB700. The adsorption sites for Cd²⁺ and Ni²⁺ on the biochars largely overlapped, and the binding of Cd²⁺ and Ni²⁺ to these sites was affected by the occupation sequence of these metals. For Cd²⁺ and Ni²⁺ adsorption in the binary system, cation exchange and precipitation were the dominant adsorption mechanisms on RB400 and RB700, respectively, accounting for approximately 36% and 60% of the adsorption capacity. Competition decreased the contribution of cation exchange but increased that of precipitation and other potential mechanisms. Results from this study suggest that types and concentrations of metal ions should be taken into account when removing metal contaminants from water or soil using biochars.
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23586. 题目: Uptake of phosphate by Synechocystis sp. PCC 6803 in dark conditions: Removal driving force and modeling
文章编号: N18112802
期刊: Chemosphere
作者: Yun Zhou, Andrew K. Marcus, Levi Straka, Everett Eustance, YenJung Sean Lai, Siqing Xia, Bruce E. Rittmann
更新时间: 2018-11-28
摘要: Rapid uptake of inorganic phosphate (Pi) by microalgae should occur through two processes operating in parallel: onto extracellular polymeric substances (EPS) and intracellular polymeric substances (IPS). Most previous studies focused only on overall Pi uptake and ignored the roles of EPS. We investigated the two-step removal of Pi by Synechocystis sp. PCC 6803 in dark conditions (i.e., without incorporation of Pi into newly synthesized biomass). We also developed a model to simulate both steps. Experimental results with Synechocystis confirmed that Pi in the bulk solution was removed by the two uptake mechanisms operating in parallel, but with different kinetics. All uptake rates decreased with time, and the Pi uptake rate by IPS was much higher than that by EPS at all times, but EPS had a larger maximum Pi-storage capacity -- 33–48 mgP/gCOD_EPS versus 15–17 mgP/gCOD_IPS. Synechocystis had a maximum Pi-storage capacity in the range of 22–28 mgP/g dry biomass. Protein in EPS and IPS played the key role for binding Pi, and biomass with higher protein content had greater Pi-storage capacity. Furthermore, biomass with low initial stored Pi had faster Pi-uptake kinetics, leading to more Pi removed from the bulk solution. This work lays the foundation for using microalgae as a means to remove Pi from polluted water and for understanding competition for Pi in microbial communities.
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23587. 题目: Variations of DOM quantity and compositions along WWTPs-river-lake continuum: Implications for watershed environmental management
文章编号: N18112801
期刊: Chemosphere
作者: Yulai Wang, Yunyun Hu, Changming Yang, Qiongjie Wang, Degang Jiang
更新时间: 2018-11-28
摘要: Wastewater effluent makes up an increasingly large percentage of surface water supplies, but the impacts of discharge of effluent organic matter (EfOM) on receiving riverine and lacustrine dissolved organic matter (DOM) is still largely unknown. In the present study, we investigated variations of DOM quantity and quality along wastewater treatment plants (WWTPs)-river-lake continuum during drought periods, and made a tentative discussion on its implications for watershed environmental management. We used dissolved organic carbon (DOC) concentrations, UV absorption coefficients and excitation-emission-matrixs (EEMs) fluorescence spectroscopy combined with fluorescence regional integration (FRI) to characterize EfOM and riverine and lacustrine DOM along WWTPs-river-Chaohu Lake continuum. Our results showed that changes in DOM quantity and quality in receiving waterbodies were related to EfOM discharged from WWTPs and external input of DOM along inflowing river. Specifically, we found that the ratio of protein-like/humic-like notably decreased (P < 0.05), and %humic-like increased (P < 0.01) along WWTPs-river-lake continuum. Furthermore, the recent autochthonous contribution index (BIX) and the humification index (HIX) values showed that these variations of DOM composition were attributed to microbial degradations in receiving waterbodies. We concluded that the changes of DOM quantity and quality along WWTPs-river-lake continuum had important implications for DOM behaviors, and offered some novel ideas for watershed environmental management.
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23588. 题目: Microbiome-Triggered Transformations of Trace Organic Chemicals in the Presence of Effluent Organic Matter in Managed Aquifer Recharge (MAR) Systems
文章编号: N18112706
期刊: Environmental Science & Technology
作者: Karin Hellauer, Jenny Uhl, Marianna Lucio, Philippe Schmitt-Kopplin, Daniel Wibberg, Uwe Hübner, Jörg E. Drewes
更新时间: 2018-11-27
摘要: It is widely assumed that biodegradation of trace organic chemicals (TOrCs) in managed aquifer recharge (MAR) systems occurs via a cometabolic transformation with dissolved organic carbon serving as primary substrate. Hence, the composition facilitating bioavailability of the organic matter seems to have a great impact on TOrCs transformation in MAR systems. The aim of this study was to elucidate the character of effluent organic matter present in the feedwater of a simulated sequential MAR system throughout the infiltration by use of FT-ICR-MS analyses as well as spectroscopic methods. Furthermore, compositional changes were correlated with TOrCs targeted throughout the system as well as the abundance of different microbial phyla. On the basis of their behavior throughout the infiltration system in which different redox and substrate conditions prevailed, TOrCs were classified in four groups: easily degradable, redox insensitive, redox sensitive, and persistent. Masses correlating with persistent TOrCs were mainly comprised of CHNO-containing molecules but also of CHO which are known as carboxyl-rich alicyclic molecules, while CHOS and CHNOS can be neglected. Easily degradable TOrCs could be associated with CHNO-, CHO-, and CHOS-containing compounds. However, a shift of molecular compounds to mostly CHOS was observed for redox-insensitive TOrCs. Three hundred thirty eight masses correlated with removal of redox-sensitive TOrCs, but no distinct clustering was identified.
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23589. 题目: Changes in long chain alkenone distributions and Isochrysidales groups along the Baltic Sea salinity gradient
文章编号: N18112705
期刊: Organic Geochemistry
作者: Jérôme Kaiser, Karen J. Wang, Derek Rott, Gaoyuan Li, Yinsui Zheng, Linda Amaral-Zettler, Helge W. Arz, Yongsong Huang
更新时间: 2018-11-27
摘要: Isochrysidales species of the phylum Haptophyta are the exclusive producers of C₃₇ to C₄₂ long chain alkyl ketones, also called long chain alkenones (LCAs). While LCA distribution is known to vary with temperature and salinity, it is difficult to tease apart the direct effects of environmental parameters vs changes in the LCA-producing organisms. The Baltic Sea surface salinity gradient, which ranges from oligohaline (0.5–5 g/kg) to polyhaline (18–30 g/kg), represents a unique opportunity to study the relationships between salinity changes, species distribution and LCA biomarkers in a single ecosystem. LCA biomarkers revealed the presence of the three known Isochrysidales groups (Groups I, II and III) in Baltic Sea surface sediments, and the presence of Groups I and II were further confirmed with DNA sequencing. Group III Isochrysidales were present in the mixoeuhaline Skagerrak based on LCA signature alone. Groups I and II Isochrysidales were found for the first time in the Baltic Sea using a combination of LCAs and DNA biomarkers, solving an eighteen-year long mystery of Baltic Sea LCA-producing haptophyte identity. Group II Isochrysidales, which have a large salinity tolerance range, were spread over the Skagerrak and the complete Baltic Sea, but were characteristic for the central Baltic Sea. Oligohaline Group I Isochrysidales were representative for the northern Baltic Sea. However, evidence of Group I Isochrysidales in the central and southern Baltic Sea suggests a possible transport by surface currents since this group is typically confined to oligohaline conditions. Testing the recently developed ratio of isomeric C₃₇ ketones (RIK₃₇) against the Baltic Sea surface salinity gradient revealed a significant positive correlation. This may represent a salinity proxy reflecting the amount of Group I Isochrysidales relative to Group II Isochrysidales in oligohaline environments. The present study elucidates for the first time the identity and the spatial distribution of LCA producers thriving in a large and stable brackish environment.

23590. 题目: Soil tillage impact on the relative contribution of dissolved, particulate and gaseous (CO₂) carbon losses during rainstorms
文章编号: N18112704
期刊: Soil and Tillage Research
作者: V. Chaplot, F. Darboux, M. Alexis, L. Cottenot, H. Gaillard, K. Quenea, M. Mutema
更新时间: 2018-11-27
摘要: Although the impact of water erosion on soil carbon losses has been widely investigated, little is known about the relative contributions of dissolved, particulate and gaseous losses, a prerequisite for understanding the mechanisms of carbon (C) export from soils and designing mitigation procedures. The main objective of this study was to quantify the losses of dissolved organic and inorganic C (DOC, DIC), particulate organic C (POC) and soil CO₂ from runoff microplots on tilled (T) and no-tilled (NT) soils. The study was performed in the Beauce region in central France under Luvisols using 45 and 80 mmh⁻¹ artificial rains. At 45 mm h^-1, T plots produced C erosion at an average of 1189.7 ± 114.8 mg C m-² h^-1 with 76.9% of it being POC (915.0 ± 100.0 mg C m-² h^-1), 21.7% DOC (258.3.0 ± 7.6 mg C m-² h^-1), 1.4% (16.3 ± 7.2 mg C m-² h^-1), DIC and 0.01% CO₂. NT decreased total soil C losses by 95% (from 0.8 to 0.038 g C m-² h^-1) and soil C losses were as CO₂ only. At 80 mm h^-1, NT surprisingly increased C erosion by 40% compared to T (from 39.4 to 55.3 g C m² h^-1), with 95.5% of the C losses being POC vs 88.7% for T. These results on rainstorm-induced C fluxes from soils controlled by tillage are expected to be of future value: (1) for selecting appropriate land management that will mitigate against C losses from soils and improve soil carbon sequestration and; (2) to better understand the Global Carbon Cycle and further develop the existing models.

23591. 题目: River beads as a conceptual framework for building carbon storage and resilience to extreme climate events into river management
文章编号: N18112703
期刊: Biogeochemistry
作者: Ellen Wohl, Katherine B. Lininger, Daniel N. Scott
更新时间: 2018-11-27
摘要: River beads refer to retention zones within a river network that typically occur within wider, lower gradient segments of the river valley. In lowland, floodplain rivers that have been channelized and leveed, beads can also be segments of the river in which engineering has not reduced lateral channel mobility and channel-floodplain connectivity. Decades of channel engineering and flow regulation have reduced the spatial heterogeneity and associated ecosystem functions of beads occurring throughout river networks from headwaters to large, lowland rivers. We discuss the processes that create and maintain spatial heterogeneity within river beads, including examples of beads along mountain streams of the Southern Rockies in which large wood and beaver dams are primary drivers of heterogeneity. We illustrate how spatial heterogeneity of channels and floodplains within beads facilitates storage of organic carbon; retention of water, solutes, sediment, and particulate organic matter; nutrient uptake; biomass and biodiversity; and resilience to disturbance. We conclude by discussing the implications of river beads for understanding solute and particulate organic matter dynamics within river networks and the implications for river management. We also highlight gaps in current understanding of river form and function related to river beads. River beads provide an example of how geomorphic understanding of river corridor form and process can be used to restore retention and resilience within human-altered river networks.

23592. 题目: Restored floodplains enhance denitrification compared to naturalized floodplains in agricultural streams
文章编号: N18112702
期刊: Biogeochemistry
作者: Brittany R. Hanrahan, Jennifer L. Tank, Martha M. Dee, Matt T. Trentman, Elizabeth M. Berg, Sara K. McMillan
更新时间: 2018-11-27
摘要: Predicted changes in the timing and magnitude of storms have the potential to amplify water quality challenges associated with agricultural runoff. In agricultural streams of the Midwestern US, floodplain restoration has the potential to enhance inorganic nitrogen (N) removal by increasing the bioreactive surface area for microbially-mediated denitrification. The restoration of inset floodplains via construction of the two-stage ditch increases denitrification compared to channelized systems, however, little is known about how denitrification on restored floodplains compares to those formed naturally when stream channel management lapses. We used sacrificial microcosm incubations and membrane-inlet mass spectrometry (MIMS) to compare denitrification rates in floodplain soils collected along transects in both naturalized and restored floodplains; longitudinal transects spanned two zones in the active floodplain (near-stream, NS vs. middle, MID) and a third zone that reflected upland conditions in the riparian buffer strip (UP). Denitrification rates were 35–49% higher in the restored, inset floodplains compared to naturalized floodplains. Variation in denitrification rates were primarily explained by soil organic matter (OM) and OM was > 20% higher in restored floodplains than naturalized, highlighting the contrasts between stable, constructed floodplains with heterogeneous, depositional bars typical of naturalizing channels. Consequently, restored inset floodplains could remove > 70% more N than the naturalized floodplains during similar storm inundation events.

23593. 题目: Freeze–thaw processes and intense rainfall: the one-two punch for high sediment and nutrient loads from mid-Atlantic watersheds
文章编号: N18112701
期刊: Biogeochemistry
作者: Shreeram Inamdar, Erin Johnson, Richard Rowland, Daniel Warner, Robert Walter, Dorothy Merritts
更新时间: 2018-11-27
摘要: Large runoff, sediment, and nutrient exports from watersheds could occur due to individual extreme climate events or a combination of multiple hydrologic and meteorological conditions. Using high-frequency hydrologic, sediment, and turbidity data we show that freeze–thaw episodes followed by intense winter (February) rainstorms can export very high concentrations and loads of suspended sediment and particulate organic carbon (POC) and nitrogen (PN) from mid-Atlantic watersheds in the US. Peak suspended sediment (> 5000 mg L⁻¹), POC (> 250 mg L⁻¹) and PN (> 15 mg L⁻¹) concentrations at our 12 and 79 ha forested watersheds for the February rainfall-runoff events were highest on record and the fluxes were comparable to those measured for tropical storms. Similar responses were observed for turbidity values (> 400 FNU) at larger USGS-monitored watersheds. Much of the sediments and particulate nutrients likely originated from erosion of stream bank sediments and/or channel storage. Currently, there is considerable uncertainty about the contribution of these sources to nonpoint source pollution, particularly, in watersheds with large legacy sediment deposits. Future climate projections indicate increased intensification of storm events and increased variability of winter temperatures. Freeze–thaw cycles coupled with winter rain events could increase erosion and transport of streambank sediments with detrimental consequences for water quality and health of downstream aquatic ecosystems.

23594. 题目: Road side effect on lead content in sandy soil
文章编号: N18112604
期刊: CATENA
作者: Sarah Pariente, Zhevelev Helena, Sachs Eyal, Fragin G. Anatoly, Zilbershtein Michal
更新时间: 2018-11-26
摘要: The effect of traffic load on the spatial distribution of lead concentrations in the soil at roadsides and on traffic islands was investigated along a road in Rishon LeZion, Israel. The road comprised two segments that were used during different periods: old, which was in use since 1980; and new, which was opened to traffic in 2004. Soil samples were collected from the upper 0–2 cm soil layer from the roadsides at various distances from the road, and from beneath and between shrubs on the traffic islands. The soil sampling was conducted in 2007 — a few years after the implementation of lead-free fuel — and in 2012. For each soil sample, lead concentration and soil properties associated with lead adsorption (soil organic matter and soil texture) were determined. The amounts of lead around the old road segment were higher than those around the new one. In both sampling years, the lead concentrations at the sides of both road segments were far below the maximum permissible levels for urban and agricultural areas. However, some of the sampling points on the traffic islands of the old road showed lead contamination. Small, non-significant differences in soil lead levels were found at differing distances from the road. Lead-concentration depletion rates of about 1–7 mg kg⁻¹ yr⁻¹ were indicated. Within the traffic islands, the samples collected beneath shrubs contained higher lead concentrations than those collected between shrubs. Soil organic matter levels of <1.5% did not affect the lead concentrations, whereas those above 1.5% showed a strong positive correlation.

23595. 题目: Implication of different humic acid fractions in soils under karst rocky desertification
文章编号: N18112603
期刊: CATENA
作者: Xinyue Di, Baohua Xiao, Hui Dong, Shijie Wang
更新时间: 2018-11-26
摘要: Karst rocky desertification, a kind of intense soil degradation, has become an urgent environmental issue in the karst region of southwest China. It was found that limestone soil, a typical soil of the karst region, is more vulnerable to karst rocky desertification than adjacent other soils although limestone soil has relatively high TOC (total organic carbon) content, but underlying mechanisms remain unclear. To investigate roles of soil properties in karst rocky desertification, three major soils, limestone soil, yellow soil and yellow brown soil, of the karst region of southwest China were sampled and their total extractable humic acid (THA) were fractionated into three sub-fractions, namely, free HA (HAf), encapsulated HA (HAe) and interacted HA (HAi), with a sequential extraction method. These soils and fractionated HA samples were systematically characterized with various analysis methods and discussed. The results showed that limestone soil had higher contents of total organic content (TOC) and THA content, but its THAC/TOC (carbon in THA to TOC) ratio (23.39%) was lower than those of yellow soil (31.44%) and yellow-brown soil (30.74%); C/N ratios and total acid contents of HAe and HAi fractions, which were physically protected by soil minerals/aggregates, were much higher than those of HAf fractions, indicating that HAe and HAi could be more active and degraded easier than HAf once exposed to microbes or/and runoff erosions. Therefore, lower HAf content and significantly lower HAfC/TOC (carbon in HAf to TOC) ratio of limestone soil may underlie the observation that limestone soil showed weak resistance to karst rocky desertification compared to other adjacent soils when the site had been artificial disturbed. We believe that roles of different HA fractions to overall quality and stability of soil deserve more attention.

23596. 题目: The impact of declining oxygen conditions on pyrite accumulation in shelf sediments (Baltic Sea)
文章编号: N18112602
期刊: Biogeochemistry
作者: Katarzyna Łukawska-Matuszewska, Bożena Graca, Olga Brocławik, Tamara Zalewska
更新时间: 2018-11-26
摘要: Deterioration of oxygen conditions in water below the halocline has been observed in the Baltic Sea. Deoxygenation is linked to the reduced frequency and volume of inflows of highly saline surface water from the North Sea (major Baltic inflows—MBIs) in the second half of the twentieth century and the increased organic matter respiration due to eutrophication. In the present study, the impact of worsening oxygen conditions on pyrite content in the Gdańsk Deep (max. depth of 118 m, southern Baltic Sea) sediments was determined. Geochemical parameters (acid volatile sulfides, pyrite sulfur, reactive iron, organic carbon, sedimentation rate and sediment age) were analyzed in relation to the variation in bottom water oxygen concentration and the occurrence of MBI. The obtained results demonstrate that pyrite content in the study area decreased after 1960. The declining pyrite content coincided with the deterioration of oxygen conditions (concentration < 2 ml l⁻¹) in bottom water. In the same period, reactive iron concentration decreased and organic carbon increased in sediment. In the period 1616–1960, average pyrite accumulation rate was 322 µmol m⁻² day⁻¹. In the subsequent years, its average accumulation rate decreased to 210 µmol m⁻² day⁻¹. Fluctuations of oxygenation of bottom water in the study area were manifested by highly variable degree of pyritization (36 ± 11%) and particulate organic carbon to pyrite sulfur ratio (2.8–37).

23597. 题目: Spatial variability of organic matter properties determines methane fluxes in a tropical forested peatland
文章编号: N18112601
期刊: Biogeochemistry
作者: N. T. Girkin, C. H. Vane, H. V. Cooper, V. Moss-Hayes, J. Craigon, B. L. Turner, N. Ostle, S. Sjögersten
更新时间: 2018-11-26
摘要: Tropical peatland ecosystems are a significant component of the global carbon cycle and feature a range of distinct vegetation types, but the extent of links between contrasting plant species, peat biogeochemistry and greenhouse gas fluxes remains unclear. Here we assessed how vegetation affects small scale variation of tropical peatland carbon dynamics by quantifying in situ greenhouse gas emissions over 1 month using the closed chamber technique, and peat organic matter properties using Rock-Eval 6 pyrolysis within the rooting zones of canopy palms and broadleaved evergreen trees. Mean methane fluxes ranged from 0.56 to 1.2 mg m⁻² h⁻¹ and were significantly greater closer to plant stems. In addition, pH, ranging from 3.95 to 4.16, was significantly greater closer to stems. A three pool model of organic matter thermal stability (labile, intermediate and passive pools) indicated a large labile pool in surface peat (35–42%), with equivalent carbon stocks of 2236–3065 g m⁻². Methane fluxes were driven by overall substrate availability rather than any specific carbon pool. No peat properties correlated with carbon dioxide fluxes, suggesting a significant role for root respiration, aerobic decomposition and/or methane oxidation. These results demonstrate how vegetation type and inputs, and peat organic matter properties are important determinants of small scale spatial variation of methane fluxes in tropical peatlands that are affected by climate and land use change.

23598. 题目: More reducing bottom-water redox conditions during the Last Glacial Maximum in the southern Challenger Deep (Mariana Trench, western Pacific) driven by enhanced productivity
文章编号: N18112520
期刊: Deep-Sea Research Part II: Topical Studies in Oceanography
作者: Min Luo, Thomas J. Algeo, Hongpeng Tong, Joris Gieskes, Linying Chen, Xuefa Shi, Duofu Chen
更新时间: 2018-11-25
摘要: The modern southern Mariana Trench is characterized by oligotrophic surface waters, resulting in low primary productivity and well-oxygenated bottom waters. This study investigates changes in the redox conditions of bottom waters in the southern Mariana Trench during the Last Glacial Maximum (LGM) and their potential causes. We measured major, trace, and rare earth elements (REE) in three gravity cores (GC03, GC04, and GC05) and one box core (BC11) retrieved from the southern Challenger Deep at water depths from 5289 to 7118 m. The upper sediment layers of both GC05 and BC11 are dominated by valve fragments of the giant diatom Ethmodiscus rex, forming laminated diatom mats (LDMs). 14C-AMS dates of bulk organic matter show that the LDMs accumulated between 18.4 and 21.8 kyr B.P., corresponding to the LGM. Modest enrichments of U and Mo along with weak or absent Ce anomalies in the LDM point to suboxic conditions during the LGM. In contrast, non-LDM samples exhibit little to no enrichment of redox-sensitive elements as well as negative Ce anomalies, indicating deposition under oxic bottom-water conditions. The Ce anomalies are considered valid proxies for bottom-water redox conditions because REE signatures were acquired in the early diagenetic environment, as indicated by strong P-REE correlations and middle-REE enrichment associated with early diagenetic cycling of Fe-Mn oxyhydroxides in the sediment column followed by capture of the REE signal by biogenic and/or authigenic apatite. We postulate that the more reducing bottom-water conditions during the LGM were linked to increased primary productivity induced by enhanced Asian dust input. As shown in earlier studies, the increased primary productivity associated with Ethmodiscus rex blooms in the eastern Philippine Sea played a significant role in capturing atmospheric CO2 during the LGM. Consequently, the magnitude of atmospheric CO2 sequestration by giant diatom blooms during the LGM may have been greater than previously envisaged.

23599. 题目: Copper phosphide and persulfate salt: A novel catalytic system for the degradation of aqueous phase micro-contaminants
文章编号: N18112519
期刊: Applied Catalysis B: Environmental
作者: Charalampia Alexopoulou, Athanasia Petala, Zacharias Frontistis, Charalampos Drivas, Stella Kennou, Dimitris I. Kondarides, Dionissios Mantzavinos
更新时间: 2018-11-25
摘要: The heterogeneous activation of sodium persulfate (SPS) using copper (I) phosphide (Cu₃P) nanoparticles was tested in this work. The catalyst was synthesized via a two-step method involving preparation of Cu(OH)₂ and subsequent low temperature phosphidation and characterized with BET, XRD, TEM/HRTEM, SEM and XPS techniques. The XRD pattern showed the existence of hexagonal Cu₃P phase with mean primary crystallite size of ca. 28 nm. The XP spectra indicated the presence of residual Cu(OH)₂ and Cu₃(PO₄)₂ species on the catalyst surface, originating from the synthesis methods employed, which disappeared after exposure to reaction conditions.The activity of Cu₃P was evaluated for the degradation of antibiotic sulfamethoxazole (SMX), which occurred in short reaction times. The effect of catalyst concentration (20–80 mg/L), SPS dosage (0.05–1 g/L) and SMX concentration (0.5–4.1 mg/L) on degradation was studied. Results obtained in ultrapure water (UPW) showed that SMX degradation increases with increasing catalyst content in the range 20–80 mg/L and SPS concentration in the range 0.05–0.5 g/L. In contrast, increasing SPS concentration at 1 g/L leads to lower reaction rates. Experiments were also conducted in bottled water, secondary treated wastewater, UPW spiked with bicarbonate or chloride ions, as well as UPW containing humic acid. With the use of t-butanol and methanol as radical quenching agents,SO4•- was found to be the primary radical species responsible for SMX degradation. The simultaneous use of Cu₃P and solar irradiation as persulfate activators resulted in a synergistic effect in experiments performed in UPW and wastewater.From a mechanistic point of view, Cu₃P acts as an electron mediator or bridge to facilitate the electron-transfer processes and this is accompanied by the intermediate formation of radicals. The catalyst remains intact, thus implying the catalytic nature of the process.

23600. 题目: Distribution, degradation and bioavailability of dissolved organic matter in the East China Sea
文章编号: N18112518
期刊: Biogeochemistry
作者: Chong-Xiao Ji, Gui-Peng Yang, Yan Chen, Peng-Yan Zhang
更新时间: 2018-11-25
摘要: Water samples were collected from the East China Sea (ECS) in October 2015 to investigate the distribution, degradation and bioavailability of organic matter. Concentrations of dissolved organic carbon (DOC), total hydrolyzable amino acids (THAAs, including dissolved free, DFAA and combined fraction, DCAA), particulate amino acids (PAAs), and total dissolved carbohydrates (TDCHO, including monosaccharides, MCHO and polysaccharides, PCHO) were measured. DOC and TCHO concentrations exhibited similar distribution patterns with high values occurring at nearshore stations, revealing the effects of terrestrial input and similar source and removal pathways of DOC and TCHO. The distributions of THAA, DCAA, and PAA displayed declining trends from the north to south of the ECS. Elevated THAA values simultaneously occurred in the center of the transect. The onboard incubation experiments with surface seawater from one station showed that the values of degradation index based on amino acids decreased with the increase of dissolved inorganic nitrogen (DIN) concentrations, indicating the mineralization of THAA to DIN during degradation process. TCHO-C% and THAA-C% are defined as the percentages of carbohydrates and amino acids in DOC, respectively. There were 21 stations suffering P limitation, implying that PO₄ ³⁻ -P content was the key factor limiting the growth of phytoplankton. High TCHO-C% values were found at P-limited stations, indicating that phytoplankton preferentially produced carbohydrates when experiencing nutrient limitation. The difference of dissolved organic matter bioavailability between surface and bottom water were probably due to water stratification. Overall, the present study may have implications for the source, removal and bioavailability of organic mater in the ECS.