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25241. 题目: Oxidative removal of brilliant green by UV/S2O82?, UV/HSO5? and UV/H2O2 processes in aqueous media: A comparative study
文章编号: N18070611
期刊: Journal of Hazardous Materials
作者: Faiza Rehman, Murtaza Sayed, Javed Ali Khan, Noor S. Shah, Hasan M. Khan, Dionysios D. Dionysiou
更新时间: 2018-07-06
摘要: The removal of brilliant green (BG), a toxic organic and cationic dye, has been examined by UV/S2O82 (PS), UV/HSO5 (PMS) and UV/H2O2 processes. BG showed insignificant direct photolysis at 254 nm (i.e., 8.6% after 30 min). However, enhanced BG degradation was observed in UV/PS, UV/PMS and UV/H2O2 systems as revealed from 63.1, 47.0 and 34.8% BG degradation, respectively, at 30 min of reaction time, using 0.05 mM BG and 1.0 mM oxidant initial concentration. The bimolecular rate constants of OH and SO4 with BG were determined to be 2.35 × 109 and 2.21 × 109 M 1 s 1, respectively. Electrical energy per order (EE/O) values for UV/PS, UV/PMS and UV/H2O2 processes were calculated to be 5.4, 6.8, and 7.8 KWh/m3/order, respectively. The addition of humic acid (HA) and inorganic anions inhibited the degradation of BG by UV/PS in the order of NO2 > HA > HCO3 > Cl > NO3 ≈ SO42 . The results of frontier electron densities (FEDs) showed that C-atom holding the three rings (C7), and C-atoms at para positions to N-alkyl groups of the two rings (C4 and C14) are the predominant sites for radical addition. Furthermore, nine degradation products (DPs) of BG were detected experimentally using LC/MS/MS.

25242. 题目: Degradation behavior of palm oil mill effluent in Fenton oxidation
文章编号: N18070610
期刊: Journal of Hazardous Materials
作者: Disni Gamaralalage, Osamu Sawai, Teppei Nunoura
更新时间: 2018-07-06
摘要: An in-depth study on degradation behavior of palm oil mill effluent (POME) in Fenton oxidation was accomplished with complete carbon and nitrogen balances. Experiments were conducted for real POME with a pH range of 2-5. POME contained high COD (50000 mg/L), nitrogen (520 mg/L) and phosphorous (510 mg/L). Carboxylic acids and phenol covered 88% of organic carbons while ammonia, NO2- and NO3- contributed for 73% of nitrogen. Most of carboxylic acids and phenol were decomposed forming easily-biodegradable formic, phthalic and acetic acids, and further decomposed to carbonate and gaseous carbon dioxide. Part of carbon in liquid phase in POME transferred to solid phase by oligomerization of aromatic compounds. Ammonia was oxidized to NO2-, NO3- and gaseous N2 while, acetamide degradation led to ammonia formation. 99.9% of phosphorus was removed. Increasing H2O2 concentration elevated organic reduction and the highest TOC reduction of 91% was obtained at TOC:H2O2:Fe2+ molar ratio of 1:3.7:0.6 within 90-180 min which is extremely faster over the available biological treatments. Under the reaction conditions used in this study, Fenton oxidation at pH 3 showed the best result in terms of TOC reduction. Outcomes of this study will provide a platform for advanced oxidation processes and POME treatment.

25243. 题目: Evaluation of gas resource potentiality, geochemical and mineralogical characteristics of Permian shale beds of Latehar-Auranga Coalfield, India
文章编号: N18070609
期刊: International Journal of Coal Geology
作者: Vinod Atmaram Mendhe, Vivekanand Kumar, Vinod Kumar Saxena, Mollika Bannerjee, Alka Damodhar Kamble, Bhagwan D. Singh, Subhashree Mishra, Sadanand Sharma, Jaywardhan Kumar, Atul Kumar Varma, Divya Kumari Mishra, Suresh Kumar Samad
更新时间: 2018-07-06
摘要: The shale beds associated with Permian coal-bearing Barakar Formation of the Latehar-Auranga coalfield (north Koel Valley), India have been investigated for the hydrocarbon prospects and their critical reservoir properties. The shale core samples were collected from boreholes drilled in three different blocks like Gowa, Jagaldaga and Banhardih. The shale core samples are examined for in-situ gas content, desorbed gas composition, geochemical, Rock-Eval, scanning electron microscopy (SEM), X-ray diffraction (XRD), high pressure CH4 adsorption isotherm, porosity and permeability aspects. The shales are rich in carbonaceous and silty materials with alternate bands of intercalations; suggesting deposition of the sediments and organic matters by slow or wavering river currents under the reducing environment. The van Krevelen diagram of H/C and O/C atomic ratio of the shales has demonstrated type III/IV kerogens; specifying that organic matters transformed from the fluvio-terrestrial depositional conditions to the diagenesis and catagenesis stages and placed in wet to dry gas window (H/C ratio < 0.5). The values of in-situ gas, lost gas, desorbed gas and residual gas contents are ranging from 1.06–7.02, 0.21–0.98, 0.35–4.16 and 0.42–2.45 cc/g, respectively. The Langmuir volume (VL) is varying between 5.6 and 0.9 cc/g, when values of VL compared to the in-situ gas revealed low to moderate gas saturation (26.86–73.75%) of the shale beds. The negative trend of Langmuir pressure (PL) with depth suggests affinity of CH4 to the shale pore surfaces. The plot of lower hydrocarbons ratios like (C2/C1) × 1000 and (C3/C1) × 1000 shows the dry thermal origin of desorbed gas. The Rock-Eval pyrolysis constituents like S1, S2, S3, PI, Tmax, TOC, HI, OI and Calc. VRo% varies from 0.11–0.47, 3.45–28.34 mg HC/g, 0.11–0.89 mg CO2/g, 0.00–0.07, 414–456 °C, 1.28–16.26 wt%, 39.54–821.45 mg HC/g TOC, 1.52–20.00 mg CO2/g TOC and 0.29–1.05% respectively.The plots of hydrogen index (39.54–821.45 mg HC/g TOC) with calculated VRo (0.29–1.05%) and Tmax (414–456 °C) are signifying types I, II, III and IV kerogen in the shales prone to generate oil, wet and dry gas placed in immature to mature regions. The positive linear correlation of the VL with kaolinite and illite contents suggests that mainly clays contribute to the formation of shale matrix. The SEM images show six types of pore: i) lenticular open pores along the fissility, ii) altered pores due to weathering, iii) intergranular pores, iv) intermingled pores between crystal lattices, v) partially filled pores associated with clays and minerals, and vi) evolved pores by cracking of the organic compounds. The values of porosity and permeability have been measured under reservoir simulated confining pressure, and are ranging from 0.87–8.18% and 0.08–1.45 mD, respectively. This shows poor connectivity between the pores and fracture mechanisms controlled by the clay and minerals. It is summarized that the studied shales of Latehar-Auranga Coalfield have a low to moderate gas potential, based on their in-situ gas, TOC content (1.28–16.26 wt%), sorption capacity, Tmax values and thermal maturity. Moreover, the significant residual volume, low porosity and low permeability are the most critical properties for shale gas resource development at the Latehar-Auranga coalfield.

25244. 题目: A synthetic analysis of livestock manure substitution effects on organic carbon changes in China's arable topsoil
文章编号: N18070608
期刊: CATENA
作者: Fengling Ren, Xubo Zhang, Jian Liu, Nan Sun, Zhigang Sun, Lianhai Wu, Minggang Xu
更新时间: 2018-07-06
摘要: Application of livestock manure has been recognized as an important strategy for enhancing soil organic carbon (SOC) stocks. However, the magnitude of manure application impacts on SOC changes as compared with conventional mineral fertilizers still needs to be better assessed. In this study, we conducted a meta-analysis to address the effects of various fertilization practices on SOC changes in China's arable topsoil. The analysis was based on 148 peer reviewed articles reporting 69 sites and 729 observations with an average experimental duration of 18 years across China. We compared the response of SOC content to application of manure alone (M) or manure plus mineral fertilizers (NPKM) with the SOC response to NPK or no fertilizers (Control). We systematically analyzed how SOC responses were influenced by different environmental and management factors (land use, climate and soil properties, etc.). First, the retention coefficient of manure was used to present the percentage of C input from manure “converted” to SOC. Compared to Control, on average, manure had C-retention coefficients of 31% ± 12% (95% Confidence Interval, CI) and 18% ± 2% for the experimental duration of ≤10 years and >10 years, respectively. When compared to NPK, manure had C-retention coefficients of 29% ± 13% and 9% ± 3% for the experimental duration of ≤10 years and >10 years, respectively. In addition, compared to Control and NPK, application of manure increased SOC content by 0.23–0.26 and 0.18–0.19 g kg 1 yr 1, respectively. The results also indicated that the mean differences of SOC change between the treatments with or without manure application were mainly controlled by soil properties (28–43%) and anthropogenic farming practices (21–27%). Our results highlight the significance of improving or maintaining SOC stocks by manure applications, and provide insights for making manure application recommendations or guidelines to improve SOC stocks of China's cropland based on soil properties, climatic conditions and management practices.

25245. 题目: Soil organic carbon stocks controlled by lithology and soil depth in a Peruvian alpine grassland of the Andes
文章编号: N18070607
期刊: CATENA
作者: Songyu Yang, Erik Cammeraat, Boris Jansen, Michael den Haan, Emiel van Loon, Jorge Recharte
更新时间: 2018-07-06
摘要: The soil is the largest carbon (C) pool in the terrestrial ecosystem, and soil organic carbon (SOC) stocks play an important role in global C dynamics. Alpine grasslands of the Andes are characterized by high SOC stocks. Quantifying SOC stocks and unraveling key factors controlling SOC stocks, is necessary to obtain a better understanding of the dynamics of the large C stocks in this environment. However, most studies on C dynamics of the Andes focus on volcanic-ash soils, whereas information about non-volcanic ash soils in this region is scarce. Our objectives were: (i) to estimate SOC stocks in an alpine grassland of the Peruvian Andes (7° 11′S, 78° 35′W) with parent materials other than volcanic ash, and (ii) to identify the underlying soil formation and environmental (SFE) factors and soil properties explaining observed patterns of SOC stocks. We sampled 69 plots up to the parent material to measure soil properties and to calculate SOC stocks, in relation to lithology, land use, grazing intensity, slope angle, slope position and altitude. We applied linear models to identify key factors controlling SOC stocks. Our results showed that total SOC stocks had a mean value of 215 ± 21 T ha 1, whereas SOC stocks of the upper 10 cm and 40 cm comprised 29.3% and 80.0% of total SOC stocks respectively. The variation of the total SOC stocks was mainly explained by soil depth and soil moisture. When soil depth and soil moisture were controlled as conditional variables, lithology became the key factor controlling the total SOC stocks. For the SOC stocks of the upper 10 cm, soil moisture explained a large part of the variation, whereas lithology, grazing intensity and altitude were also significant predictors. Our results also show that when soils are sampled with limited depths instead of the entire soil profile, SOC stocks can be underestimated, and the effects of the SFE factors on SOC stocks can be overestimated.

25246. 题目: Characterization and evaluation of a tropical peat for the removal of Cr(VI) from solution
文章编号: N18070606
期刊: Environmental Earth Sciences
作者: Marilia Mayumi Augusto dos Santos, Mirian Chieko Shinzato, Juliana Gardenalli de Freitas
更新时间: 2018-07-06
摘要: Tropical peat soils present higher ash content than those generated at temperate climate areas. Therefore, this study evaluated the characteristics of a Brazilian organic soil (OS), commercialized as peat, as well as its capacity in removing Cr(VI) from contaminated waters. The OS is composed of 35.5 wt% of organic matter and 56 wt% of inorganic fraction (ash), which is formed by minerals and phytoliths rich in silica (29.2 wt%) and alumina (23.6 wt%). The Cr(VI) removal tests were carried out in batch and column systems using OS and solutions of Cr(VI) prepared with distilled water and groundwater. Batch tests revealed that the organic substances in the OS caused the reduction of Cr(VI) to Cr(III), with an efficiency depending on solution pH. At pH 5.0 the Cr(VI) removal was 0.45 mg g 1 in 24 h; whereas at pH 2.0, this removal increased to 1.10 mg g 1. Since this redox reaction is very slow, the removal of Cr(VI) at pH 5.0 increased to around 2 mg g 1 after 5 days. The removal of Cr(VI) was more effective in the column tests than in the batch test due to the greater solid/solution ratio, and their half-lives were 4.4 and 26.2 h, respectively. Chemical analysis indicated that Cr(VI) was reduced by the humic substances of OS, followed by the precipitation and/or adsorption of Cr(III) into the organic and inorganic components, as anatase. The presence of Cr(III) increased the stability of anatase structure, avoiding its transformation into rutile, even after being heated at 800 °C/2 h.

25247. 题目: Impact of drilling mud on chemistry and microbiology of an Upper Triassic groundwater after drilling and testing an exploration well for aquifer thermal energy storage in Berlin (Germany)
文章编号: N18070605
期刊: Environmental Earth Sciences
作者: Simona Regenspurg, Mashal Alawi, Guido Bl?cher, Maria B?rger, Stefan Kranz, Ben Norden, Ali Saadat, Traugott Scheytt, Lioba Virchow, Andrea Vieth-Hillebrand
更新时间: 2018-07-06
摘要: After completion of an exploration well, sandstones of the Exter Formation were hydraulically tested to determine the hydraulic properties and to evaluate chemical and microbial processes caused by drilling and water production. The aim was to determine the suitability of the formation as a reservoir for aquifer thermal energy storage. The tests revealed a hydraulic conductivity of 1–2 E-5 m/s of the reservoir, resulting in a productivity index of 0.6–1 m3/h/bar. A hydraulic connection of the Exter Formation to the overlaying, artesian “Rupelbasissand” cannot be excluded. Water samples were collected for chemical and microbiological analyses. The water was similarly composed as sea water with a maximum salinity of 24.9 g/L, dominated by NaCl (15.6 g/L Cl and 7.8 g/L Na). Until the end of the tests, the water was affected by drilling mud as indicated by the high pH (8.9) and high bicarbonate concentration (359 mg/L) that both resulted from the impact of sodium carbonate (Na2CO3) additives. The high amount of dissolved organic matter (> 58 mg/L) and its molecular-weight distribution pattern indicated that residues of cellulose, an ingredient of the drilling mud, were still present at the end of the tests. Clear evidence of this contamination gave the measured uranine that was added as a tracer into the drilling mud. During fluid production, the microbial community structure and abundance changed and correlated with the content of drilling mud. Eight taxa of sulfate-reducing bacteria, key organisms in processes like bio-corrosion and bio-clogging, were identified. It can be assumed that their activity will be affected during usage of the reservoir.

25248. 题目: Redoximorphic Bt horizons of the Calhoun CZO soils exhibit depth-dependent iron-oxide crystallinity
文章编号: N18070604
期刊: Journal of Soils and Sediments
作者: Chunmei Chen, Diego Barcellos, Daniel D. Richter, Paul A. Schroeder, Aaron Thompson
更新时间: 2018-07-06
摘要: Purpose: Iron (Fe) oxyhydroxides and their degree of ordering or crystallinity strongly impact the role that Fe plays in ecosystem function. Lower crystallinity phases are generally found to be more reactive than higher crystallinity phases as sorbents for organic matter and chemical compounds, as electron acceptors for organic matter mineralization or as electron donors for dysoxic respiration. We investigated Fe solid phase speciation as a function of soil depth in a redoximorphic upland soil profile. Materials and methods: We examined a redoximorphic upland soil profile, which displayed alternating Fe-enriched and Fe-depleted zones of the Bt horizons with platy structure from 56 to 183 cm depth at the Calhoun Critical Zone Observatory in South Carolina, USA. Redoximorphic Fe depletion and enrichment zones were sampled to enable a detailed investigation of Fe mineralogy during redox transformations. All samples were characterized by total elemental analysis, X-ray diffraction, and 57Fe M ssbauer spectroscopy. Results and discussion: Total Fe in the Fe-enriched and Fe-depleted zones was 26.3 – 61.2 and 15.0 – 22.7 mg kg 1 soil, respectively, suggesting periodic redox cycling drives Fe redistribution within the upland soil profile. The M ssbauer data clearly indicated goethite (56 – 74% of total Fe) and hematite (7 – 31% of total Fe) in the Fe-enriched zones, with the proportion of hematite increasing with depth at the expense of goethite. In addition, the overall crystallinity of Fe phases increased with depth in the Fe-enriched zones. In contrast to Fe-enriched zones, Fe-depleted zones contained no hematite and substantially less goethite (and of a lower crystallinity) but more aluminosilicates-Fe(III) (e.g., hydroxy-interlayered vermiculite, biotite, kaolinite) with XRD and M ssbauer data suggesting a shift from oxidized biotite-Fe(III) at depth to hydroxy-interlayered vermiculite plus low-crystallinity goethite in the Fe-depleted zones in the upper Bt. Conclusions: Our data suggest the varied crystalline states of hematite and goethite may be important for Fe reduction over long-term time scales. The persistence of low-crystallinity Fe phases in Fe depletion zones suggests that both dissolution and re-precipitation events occur in the Fe-depleted layers. These variations in Fe phase abundance and crystallinity within similar redoximorphic features suggest that Fe likely shifts ecosystem roles as a function of soil depth and likely has more rapid Fe cycling in the upper Bt horizons in upland soils, while serving as a weathering engine at depth.

25249. 题目: Climate and plant controls on soil organic matter in coastal wetlands
文章编号: N18070602
期刊: Global Change Biology
作者: Michael J. Osland , Christopher A. Gabler , James B. Grace , Richard H. Day , Meagan L. McCoy , Jennie L. McLeod , Andrew S. From , Nicholas M. Enwright , Laura C. Feher , Camille L. Stagg , Stephen B. Hartley
更新时间: 2018-07-06
摘要: Coastal wetlands are among the most productive and carbon‐rich ecosystems on Earth. Long‐term carbon storage in coastal wetlands occurs primarily belowground as soil organic matter (SOM). In addition to serving as a carbon sink, SOM influences wetland ecosystem structure, function, and stability. To anticipate and mitigate the effects of climate change, there is a need to advance understanding of environmental controls on wetland SOM. Here, we investigated the influence of four soil formation factors: climate, biota, parent materials, and topography. Along the northern Gulf of Mexico, we collected wetland plant and soil data across elevation and zonation gradients within ten estuaries that span broad temperature and precipitation gradients. Our results highlight the importance of climate‐plant controls and indicate that the influence of elevation is scale and location dependent. Coastal wetland plants are sensitive to climate change; small changes in temperature or precipitation can transform coastal wetland plant communities. Across the region, SOM was greatest in mangrove forests and in salt marshes dominated by graminoid plants. SOM was lower in salt flats that lacked vascular plants and in salt marshes dominated by succulent plants. We quantified strong relationships between precipitation, salinity, plant productivity, and SOM. Low precipitation leads to high salinity, which limits plant productivity and appears to constrain SOM accumulation. Our analyses use data from the Gulf of Mexico, but our results can be related to coastal wetlands across the globe and provide a foundation for predicting the ecological effects of future reductions in precipitation and freshwater availability. Coastal wetlands provide many ecosystem services that are SOM dependent and highly vulnerable to climate change. Collectively, our results indicate that future changes in SOM and plant productivity, regulated by cascading effects of precipitation on freshwater availability and salinity, could impact wetland stability and affect the supply of some wetland ecosystem services.

25250. 题目: Lateral carbon transfer from erosion in noncroplands matters
文章编号: N18070601
期刊: Global Change Biology
作者: Pasquale Borrelli , Panos Panagos , Emanuele Lugato , Christine Alewell , Cristiano Ballabio , Luca Montanarella , David A. Robinson
更新时间: 2018-07-06
摘要: This study combines two unprecedentedly high resolution (250 × 250 m) maps of soil erosion (inter‐rill and rill processes) and soil organic carbon to calculate a global estimate of erosion‐induced organic carbon (C) displacement. The results indicate a gross C displacement by soil erosion of Pg C/year. The greatest share of displaced C (64%) comes from seminatural lands and forests. This suggests that lateral C transfer from erosion in noncroplands may play a more important role than previously assumed.

25251. 题目: Isotope record of mineralogical changes in a spectrum of aqueously altered CM chondrites
文章编号: N18070506
期刊: Geochimica et Cosmochimica Acta
作者: Elishevah M.M.E. van Kooten, Larissa L. Cavalcante, Kazuhide Nagashima, Takeshi Kasama, Zoltan I. Balogh, Zan Peeters, Silver Sung-Yun Hsiao, Hsien Shang, Der-Chuen Lee, Typhoon Lee, Alexander N. Krot, Martin Bizzarro
更新时间: 2018-07-05
摘要: The recent fall of the relatively unaltered CM chondrite Maribo provides a unique opportunity to study the early stages of aqueous alteration on the CM chondrite parent body. We show using transmission electron microscopy of a matrix FIB-section from Maribo that this meteorite mainly appears to consist of tochilinite-cronstedtite intergrowths (TCIs), but also contains regions of amorphous or nanocrystalline silicates, anhydrous silicates and FeNi metal aggregates with thin iron oxide rims, suggesting that it experienced aqueous alteration to a relatively small degree. A comparison of Maribo with increasingly altered CM chondrites such as Jbilet Winselwan and Bells shows that during progressive aqueous alteration (1) the TCIs are replaced by coarser sulfides and increasingly Mg-rich serpentine, and (2) the abundance of 15 N -rich hotspots increases, whereas the magnitude of their 15 N enrichment decreases. We observe that the overall N isotope variability related to aqueous alteration is an order of magnitude lower than the variability observed between different chondrite groups. We suggest these high order differences are the result of heterogeneous accretion of insoluble or soluble organic carriers of 15 N to the different chondrite parent bodies. D/H ratios of matrices from Maribo, Jbilet Winselwan and Bells increase with progressive aqueous alteration, a trend that is opposite to expectations of mixing between D-poor water and D-rich organic matter. We argue that this behaviour cannot be related to Fe oxidation or serpentinization reactions and subsequent loss of D-poor H2 gas. We offer an alternative hypothesis and suggest that CM chondrites experienced two-stage aqueous alteration. During the first stage occurring at relatively low temperature, mixing of increasing amounts of D-poor water with D-rich organic matter results in a decrease of D/H ratio with increasing degree of alteration. During the second stage of alteration occurring at relatively high temperature (T < 300 °C), decomposition of TCIs in CMs of petrologic type <2.7 releases gaseous D-poor water that results in increase of the D/H ratio of the CM matrices. Finally, we report on changes in the organic structure of Maribo, Jbilet Winselwan and Bells using Carbon-K and Nitrogen-K edge electron energy loss spectroscopy. The organic matter initially has higher aromatic/aliphatic ratios (e.g., Maribo) and lower abundances of ketone and carboxyl functional groups, which we suggest are the result of chemical degradation of double bonded carbon from oxidation during hydrothermal alteration. Consequently, we propose that the organic matter of the CM chondrite Paris, for which lower aromatic/aliphatic ratios have been observed, may have been different from Maribo, perhaps reflecting the early accretion of Paris relative to Maribo.

25252. 题目: Lipid compound classes display diverging hydrogen isotope responses in lakes along a nutrient gradient
文章编号: N18070505
期刊: Geochimica et Cosmochimica Acta
作者: S. Nemiah Ladd, Daniel B. Nelson, Carsten J. Schubert, Nathalie Dubois
更新时间: 2018-07-05
摘要: Compound specific hydrogen isotope ratios (2H/1H) of lipid biomarkers preserved in sediments are used as paleohydrologic proxies. However, several variables, including contributions from different source organisms and their growth rates, can influence 2H/1H fractionation between lipids and source water. Significant uncertainties remain about how these factors combine to produce the net 2H/1H signal exported to sediments. To assess the influence of phosphorus availability on 2H/1H ratios of lipids accumulating in lake sediments, we analyzed surface sediments and sediment traps from ten central Swiss lakes representing a wide range of trophic states. In agreement with results from laboratory cultures, 2H/1H fractionation for the diatom biomarker brassicasterol (24-methyl cholest-5,22-dien-3β-ol) increased in more productive lakes (0.6 ± 0.1‰ per μg/L total P in sediment traps and surface sediments). In contrast, 2H/1H fractionation for phytol, the isoprenoid side-chain moiety of chlorophyll, decreased with increasing total P ( 0.4 ± 0.1‰ per μg/L total P in sediment traps), suggesting that different biochemical mechanisms are responsible for changes in 2H/1H fractionation for each type of isoprenoidal lipid. Opposing changes in 2H-fractionation for sterols and phytol cause their 2H/1H ratios to converge as total P increases. This response may be a new tracer for phytoplankton growth conditions and is not influenced by the source water isotope value. Interpreting the 2H/1H ratios of short to long chain (C14–C30) n-alkanoic acids and n-alkanols is complicated by likely contributions from heterotrophs and/or vascular plants. These values generally did not correlate with lake water isotopes, nor did their fractionation factors correlate with total P. For most lipids there was no significant difference between sediment trap and surface sediment 2H/1H ratios. However, n-C14–n-C18 fatty acids were 2H-enriched in the surface sediments, most likely due to degradation in the water column. Our results indicate that interpretations of short-chain fatty acid 2H/1H ratios as a water isotope signal likely require supporting information about ecological conditions and community structure, but that paired H isotope measurements of phytoplankton-derived sterols and phytol may be developed as a proxy for phytoplankton growth.

25253. 题目: Benthic nutrient cycling at the sediment-water interface in a lagoon fish farming system (northern Adriatic Sea, Italy)
文章编号: N18070504
期刊: Science of The Total Environment
作者: Elisa Petranich, Stefano Covelli, Alessandro Acquavita, Cinzia De Vittor, Jadran Faganeli, Marco Contin
更新时间: 2018-07-05
摘要: Metabolism and carbon, oxygen, and nutrient fluxes (DIC, DOC, DO2, NO2 , NO3 , NH4 +, PO4 3 and SiO4 4 ) were studied during three surveys at two sites (VN1 and VN3) located at a fish farm at the Marano and Grado Lagoon (northern Adriatic Sea), using an in situ benthic chamber. Field experiments were conducted in July and October 2015 and March 2016 at a depth of approximately 2 m along the main channels of the fish farm. Water samples were collected by a scuba diver every 2 h in order to investigate daily fluxes of solutes across the sediment-water interface (SWI). Regarding the solid phase, Corg/Ntot and Corg/Porg molar ratios suggested an autochthonous marine origin of the organic matter and a minor preservation of P in the sediments, respectively; high values of sulphur (Stot) were also encountered (0.8–2%). The conditions at VN3 were mostly anoxic with high NH4 + levels (30–1027 μM) and the absence of NO3 . Substantial daily patterns of all solutes occurred especially in autumn and winter. On the contrary, fluxes at VN1 were less pronounced. Usually, inverse correlations appeared between dissolved O2 and DIC trends, but in our system this was observed only at VN3 in autumn and accomplished by a parallel increase in NH4 +, PO4 3 and SiO4 4 during intense nutrient regeneration. These results are significantly different than those reported for open lagoon environments, where nutrient regeneration at the SWI and in surface sediments is the primary source of nutrients available for assimilation processes, especially during the warmer period of the year when the natural nutrient input by fresh water inflows is limited. Due to the importance of this site for aquaculture, biodiversity and ecosystem services, useful suggestions have been provided from this study in order to improve the quality of this unique aquatic system.

25254. 题目: Characterisation of dissolved organic matter using Fourier-transform ion cyclotron resonance mass spectrometry: Type-specific unique signatures and implications for reactivity
文章编号: N18070503
期刊: Science of The Total Environment
作者: Xi-Zhi Niu, Mourad Harir, Philippe Schmitt-Kopplin, Jean-Philippe Croué
更新时间: 2018-07-05
摘要: This study investigated the chemodiversity and unique signatures for dissolved organic matter (DOM) from different types of water using high-resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). Eight freshwater hydrophobic DOM (HPO) share 10–17% formulas that were mainly lignin-like compounds. Unique signatures were synthesized: unique to the high-humic HPO (Suwannee River and Blavet River) were condensed aromatic and some aliphatic compounds with H/C > 1.5 and O/C < 0.2, which is considered as decisive of these black river water. Medium-humic isolates (Loire River, Seine River, South Platte River, and Ribou Dam) did not show explicit unique signatures. Nonetheless, enhanced chemodiversity was observed for medium-humic isolates extracted from a variety of indigenous environmental conditions. As an example, South Platte River HPO isolated in winter showed signatures similar to low-humic HPO (Colorado River), i.e., predominantly aliphatic CHO (H/C > 1.0). Effluent HPO was mainly aliphatic molecules with 0.2 < O/C < 0.5 and enriched in S-bearing molecules, and molecules unique to glacial DOM (Pony Lake) incorporated N-bearing compounds that were inferiorly oxidized and were considered as microbial-derived. The weight-averaged double bond equivalent and elemental ratio derived from FTICR-MS were compared with SUVA254 and the results from elemental analysis. This acts as the first study to synthesize unique chemical compositions that distinguish different types of DOM and determine certain reactivity. It is also a significant reference for future studies using similar types of DOM.

25255. 题目: Culture and horticulture: Protecting soil quality in urban gardening
文章编号: N18070502
期刊: Science of The Total Environment
作者: Francesca Bretzel, Claudia Caudai, Eliana Tassi, Irene Rosellini, Manuele Scatena, Roberto Pini
更新时间: 2018-07-05
摘要: Urban cultivation for food production is of growing importance. The quality of urban soil can be improved by tillage and the incorporation of organic matter, or can be degraded by chemical treatments. Urban gardeners have a role in this process, through the selection of various cultivation techniques. Our study focuses on an allotment area in the town of Pisa (Italy), which since 1995 has been run as a municipal vegetable garden by the residents. We analysed the soil and compared the data with those collected five years previously, to verify the possible changes in soil properties and fertility. We also interviewed the gardeners regarding their backgrounds, motivations and cultivation practices. We looked for possible changes in the soil quality attributable to the cultivation techniques. We found that the allotment holders influenced the soil quality through the cultivation techniques. Organic carbon, electrical conductivity and the content of copper increased unevenly in relation to the gardeners' cultivation practices. At the same time the study highlights that the urban gardeners were not completely aware of how to protect and enhance the fertility and the quality of urban soil. We believe that town councils should be responsible for providing correct information to the allotment holders and thus prevent the possible misuse of urban soil to grow food, as this can affect everyone's health.

25256. 题目: Exposure of Brazilian soil and groundwater to pollution by coccidiostats and antimicrobial agents used as growth promoters
文章编号: N18070501
期刊: Science of The Total Environment
作者: Alejandro Yopasá-Arenas, Anne Hélène Fostier
更新时间: 2018-07-05
摘要: The World Health Organization has identified antimicrobial resistance as one of the most important threats to global health. Brazil is one of the world's leading meat producers and the Brazilian use of veterinary antimicrobials as therapeutic agents and prophylactic or growth promoters in animal production remains problematic. Many antimicrobials are not completely metabolized and their excretion represents a significant source of environmental exposure. The aim of this work was to estimate the exposure risk of soil and groundwater to pollution by growth promoters (GPs) and anticoccidial additives (AAs) in Brazil by using a method based on a geographical information system (GIS). The principle adopted is that the greater the amount of animals, the greater the quantity of antimicrobials present, and the greater the soil vulnerability to pollution. Our research showed that GPs and AAs are extensively used in the Brazilian animal production system. An analysis of market data showed that zinc bacitracin, monensin, salinomycin, colistin and tylosin are representative GPs and AAs. This study presents a qualitative approach for risk assessment based on worst-case scenarios. First, the probable environmental concentration was estimated using a correlation between the number of heads of the herds of poultry and cattle, and the amounts of drug released. The leaching risk potential was characterized for each compound, as proposed in ISO 15175. The potential of soil pollution was evaluated for each antimicrobial as a function of its binding and dissipation rates. These rates were calculated using georeferenced data of organic carbon, average temperature, water balance and hydro-geological parameters. The consequences were modeled based on Brazilian soil usage. Finally, the risk was calculated by combining the different maps generated using spatial multi-criteria decision analysis. Higher risk was found for the midwest, southeast and south regions of Brazil. Groundwater was found to be more vulnerable than soil.

25257. 题目: Environmental assessment concerning trace metals and ecological risks at Guanabara Bay, RJ, Brazil
文章编号: N18070402
期刊: Environmental Monitoring and Assessment
作者: Valquiria Maria de Carvalho Aguiar, Paula Ferreira Falheiro Abuchacra, José Ant?nio Baptista Neto, Allan Sandes de Oliveira
更新时间: 2018-07-04
摘要: Three-stage sequential extraction BCR was applied to surface sediments from the west part of Guanabara Bay to assess the mobility of Zn, Cu, Pb, Ni, Cr, and Mn. Results were satisfactory for the analysis of certificate standard material (BCR 701), with recoveries between 71 (Cu) and 123% (Cr). Evaluation of organic matter composition classified the area as eutrophic (CHO:PRT > 1), with aged organic detritus at some stations. Zn exhibited by far the greatest bioavailability, with 43.49% of its concentrations associated with the exchangeable fraction. Cu and Cr showed stronger affinity for organic matter, with 51.18 and 48.73% of their concentrations, respectively, bounded to the oxidizable fraction. Pb presented higher concentrations in the reducible fraction (45.41%). The strongest lithogenic contribution was shown by Ni (31.91%) and Mn (35.44%). PCA clearly showed the determinant role of organic matter and fine sediments in the distribution of metals in the study area and also a common source for these elements, with the exception of Cu. Risk Assessment Code (RAC) established Zn as the most concerning element in the study area. The decreasing mobility order, based on the sum of the three extractable fractions of BCR, was Pb > Cu > Cr > Zn > Ni > Mn. The comparison of the results with sediments quality guidelines (SQG) proved fractionation to be mandatory in the evaluation of effective ecological risk concerning trace elements in sediments.

25258. 题目: Soil quality of an Iranian forest ecosystem after conversion to various types of land use
文章编号: N18070401
期刊: Environmental Monitoring and Assessment
作者: M. H. Rasouli-Sadaghiani, M. Barin, S. Siavash Moghaddam, C. A. Damalas, K. Ghodrat
更新时间: 2018-07-04
摘要: The impact of land-use change on parameters of the soil was evaluated in soil samples from arable land, orchard land, and grassland in West Azerbaijan, Iran, compared with their adjacent natural forestland, using some biological indices. Microbial biomass carbon (MBC); microbial basal respiration (BR); metabolic quotient (qCO2); substrate induced respiration (SIR); carbon availability index (CAI); the microbial quotient, i.e., the ratio of microbial carbon to soil organic carbon (Cmic/Corg); and soil organic carbon (SOC) were calculated in collected soil samples. Deforestation and long-term land use showed adverse effects on soil biological properties. The spatial distribution of MBC, BR, SIR, and SOC, followed the order: forestland > grassland > orchard land > arable land. SOC showed the highest decline by 67.7% in arable land, 43.6% in orchard land, and 36.3% in grassland, with an average reduction of 49.2% compared with forestland. Similarly, BR and MBC decreased by an average reduction of 41.3 and 34.8%, respectively, compared with forestland. By contrast, the qCO2 index, the CAI index, and the Cmic/Corg ratio were not affected significantly by land use, except from a significant raise of the Cmic/Corg ratio in the arable land. Land-use change exerted a remarkable negative influence on soil quality with several soil attributes affected due to cropping compared with adjacent grassland and forestland. At the field level, proper management practices that increase SOC in the soil, e.g., effective recycling of crop residues and manures, should be considered, when land is continuously cultivated.

25259. 题目: Oceanic fronts control the distribution of dissolved barium in the Southern Ocean
文章编号: N18070319
期刊: Marine Chemistry
作者: Kimberley M. Pyle, Katharine R. Hendry, Robert M. Sherrell, Oliver Legge, Andrew J. Hind, Dorothee Bakker, Hugh Venables, Michael P. Meredith
更新时间: 2018-07-03
摘要: The globally-observed relationship between oceanic barium and the macronutrient silicic acid results from the shared influence of large-scale ocean circulation and mixing on the two elements, and the inherent link between barium and organic matter formation and dissolution. A detailed examination of deviations from barium-silicon correlations can reveal variations in non-conservative processes within the marine barium cycle. Here, we present a high-resolution dataset of dissolved barium and macronutrients from the Drake Passage and the Scotia and Weddell Seas. Our new results highlight the influence of Southern Ocean frontal zones on barium cycling and the deviations of barium and macronutrient distributions as a result of spatial variations in phytoplankton assemblages and in barite formation processes. These new data also reinforce findings that water mass mixing and ocean circulation, in particular the location of oxygen minima, play a key role in barium distribution. Our findings have implications for the use of sedimentary barium as a proxy for export production, which may be complicated by physical water circulation changes or shifts in plankton community structure.

25260. 题目: Branched GDGT variability in sediments and soils from catchments with marked temperature seasonality
文章编号: N18070318
期刊: Organic Geochemistry
作者: Min Cao, Gemma Rueda, Pedro Rivas-Ruiz, M? Carmen Trapote, Mona Henriksen, Teresa Vegas-Vilarrúbia, Antoni Rosell-Melé
更新时间: 2018-07-03
摘要: The distributions of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in sediments are used as a proxy measurement to infer changes in past mean annual air temperatures (MAT). When applied to high resolution sedimentary sequences, measurement of brGDGT distributions is employed to reconstruct MAT at subdecadal time scales. In addition, brGDGT proxy estimates are also sometimes purported to be seasonally biased in environments where annual brGDGT production may not be constant during a seasonal cycle. The main aim of this study was to assess the occurrence of seasonality in the production and distribution of brGDGTs and the seasonality bias of the derived temperature proxy. For this purpose, we examined brGDGT distributions and brGDGT-derived MAT estimates in surface soils and settling/suspended particulate matter over one year, from two sites located in the same latitude but at different altitudes, in the Catalan Pyrenees, as well as at one site in southern Norway. These locations have marked seasonal temperature cycles, which were expected to maximize the possibility of detecting any seasonal bias in the production and compositions of brGDGTs. The results show that brGDGT abundance is heterogeneous and increases with soil humidity. The brGDGT distributions and some of the brGDGT-derived proxy measurements in soils are relatively stable throughout the year and do not change significantly in the suspended particulate matter in the river or settling particulate matter in traps. Our study shows that the impact of the seasonality of temperature on brGDGT distribution was absent in the soils studied, regardless of altitude or latitude on a catchment/regional scale. As soils are likely to contain a brGDGT signature which is representative of average environmental conditions in the catchment at least over decades, brGDGT proxy reconstructions derived from soil sources are more suitable to infer variability in environmental parameters over the same timescales (i.e. decades or longer). On shorter timescales (i.e. annual), sediment downcore variability in brGDGTs is likely to be related to changes derived from in situ production and sediment sources.