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26041. 题目: Multi‐sensor fusion for the determination of several soil properties in the Yangtze River Delta, China
文章编号: N18082115
期刊: European Journal of Soil Science
作者: D. Xu, R. Zhao, S. Li, S. Chen, Q. Jiang, L. Zhou, Z. Shi
更新时间: 2018-08-21
摘要: Soil organic matter (SOM), total nitrogen (TN), available nitrogen (AN), available phosphorus (AP), available potassium (AK) and pH are key chemical properties for evaluating soil fertility and quality. This study involved the integration of four soil sensors, visible near–infrared (vis–NIR) spectrometer, mid‐infrared (mid‐IR) spectrometer, portable X‐ray fluorescence (PXRF) analyser and laser‐induced breakdown spectroscopy (LIBS), to achieve rapid measurement of these soil properties. A genetic algorithm and partial least‐squares regression (GA–PLSR) was used to select characteristic bands to reduce data redundancy. We then calibrated models from three aspects: models using partial least‐squares regression (PLSR) based on single sensor data, models using PLSR based on fused sensor data, involving data combined from the four sensors into a new dataset to create a data fusion (DF) model and models with Bayesian model averaging (BMA) based on prediction results of fused sensor, involving prediction results combined from the four sensors into a new dataset to form the BMA model. The results showed the following. (i) For the single sensor, the predictive performance decreased as follows: mid‐IR > vis–NIR > LIBS > PXRF. (ii) Compared with the single sensor approach, the DF approach slightly improved or even reduced prediction accuracy and caused a large amount of redundancy. We suggest that this approach is not able to improve predictive ability. (iii) The BMA approach achieved the best prediction for the six soil properties. Our findings suggest that model averaging of vis–NIR, mid‐IR and LIBS could be a reliable and stable approach for the fast measurement of soil properties.

26042. 题目: Sorption and desorption characteristics of anionic surfactants to soil sediments
文章编号: N18082114
期刊: Chemosphere
作者: Ping Zhang, Yuan Liu, Zhejun Li, Amy T. Kan, Mason B. Tomson
更新时间: 2018-08-21
摘要: Surfactants are important environmental chemicals due to their extensive domestic and industrial applications, such as subsurface organic pollution remediation and enhanced oil recovery. However, the interaction of surfactants with subsurface material particularly the desorption behavior of surfactants is less understood. Surfactant desorption is essential to control the fate and transport of surfactants as well as organic pollutants. In this study, the sorption and desorption of linear sodium dodecylbenzene sulfonate (SDBS) and sodium hexadecyl diphenyl oxide disulfonate (DPDS) with two types of soil sediment samples are compared. Sorption of surfactants can be modeled by hydrophobic sorption. Less DPDS sorption is observed at a higher aqueous concentration, which is attributed to the competition between surfactant micelles and sediment organic matter for DPDS sorption. A significant fraction of the sorbed surfactants resists desorption, and this is not a result of surfactant precipitation or desorption kinetics. Surfactant desorption behavior is similar to the irreversible desorption of hydrocarbons from soil with only half of the resistant phase surfactant being readily extracted by heated solvent extraction. The sorption/desorption data are interpreted with a molecular topology and irreversible sorption model. The knowledge of this study can be useful in understanding the environmental fate and transport of these common anionic surfactants. The methodology developed in this study can be expanded to study the sorptive nature of a wider range of surfactants in the environment.
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26043. 题目: Nitrogen removal in domestic wastewater. Effect of nitrate recycling and COD/N ratio
文章编号: N18082113
期刊: Chemosphere
作者: L. Pelaz, A. Gómez, A. Letona, G. Garralón, M. Fdz-Polanco
更新时间: 2018-08-21
摘要: A denitrification/nitrification pilot plant was designed, built and put into operation, treating the effluent of an anaerobic reactor. The operation of the plant examined the effect of the nitrate recycling and the COD/N ratio on the nitrogen and the remaining organic matter removal at 18 °C. The system consisted of a two-stage treatment process: anoxic and aerobic. The hydraulic retention time (HRT) of the system was 1 h for the anoxic bioreactor and 2 h for the aerobic one. The increase in the nitrate recycling ratio did not cause a significant improvement in the nitrogen removal due to the insufficient carbon source. The wastewater to be treated had a C/N ratio of 1.1 showing a lack of organic carbon. The addition of methanol was a key point in the denitrification process used as a model for the traditional wastewater by-pass in the WWTP. The maximum nitrogen and organic matter removal (87.1% and 96%, respectively) was achieved with a nitrate recycling ratio of 600% and a C/N of 8.25, adjusted by methanol addition.
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26044. 题目: Heterogeneity of environments in a coastal lagoon mouth by the comparison between living and dead benthic foraminiferal assemblages (Ria de Aveiro Portugal)
文章编号: N18082112
期刊: Estuarine, Coastal and Shelf Science
作者: Maria Virginia Alves Martins, Johann Hohenegger, Fabrizio Frontalini, Lazaro Laut, Paulo Miranda, Maria Antonieta Rodrigues, Wânia Duleba, Mauro César Geraldes, Fernando Rocha
更新时间: 2018-08-21
摘要: This study provides a comparison between living (LAs) and dead (DAs) assemblages of benthic foraminifera in 137 sites located at the mouth region of the Aveiro Lagoon (N Portugal). This coastal lagoon, commonly named Ria de Aveiro, is under strong anthropogenic influence due to changes in natural hydrodynamics through engineering structures and by the input of contaminants. The sedimentary environments of the mouth area are characterized by biotic (benthic foraminifera) and sedimentological (grain size, trace metals and total organic carbon concentrations) data. The pollution load index (PLI) identifies areas of increased concentrations of potentially toxic trace metals. An innovative combination of several statistical methods and extremely detailed data analyses allowed to verify that the dead associations (DAs) and the living assemblages (LAs) are absent or reduced in the deep and most hydrodynamically active zones along the navigable waterways of the channels. Breakwaters reducing the bottom currents allow the development of larger and more diversified LAs. The most suitable areas for LAs are located close to the South Jetty and in Mira Channel excluding the navigable channel and the eastern margin. LAs have in general little similarity with the DAs. Confined zones and areas with high organic matter flux and trace metals concentrations, where the sediments are being accumulated, are particularly unfavourable environments for living foraminifera. The obtained results evidenced that marked differences in hydrodynamics determine large dissimilarities between LAs and DAs. In some environments the taphonomic effects caused by the removal and high accumulation of foraminiferal tests can significantly misrepresent the faunal composition in the fossil registry, and lead to misinterpretations about the paleoenvironmental evolution.

26045. 题目: Phospholipids as a component of the oceanic phosphorus cycle
文章编号: N18082111
期刊: Marine Chemistry
作者: Blaženka Gašparović, Abra Penezić, Richard S. Lampitt, Nilusha Sudasinghe, Tanner Schaub
更新时间: 2018-08-21
摘要: We characterize the distribution of oceanic phosphorus-containing lipids (PL) in the Northeast Atlantic by Iatroscan thin layer chromatography and high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Phospholipids are a small but significant fraction of oceanic particulate organic carbon (POC) (1.5%). We describe the distribution of 1862 PL compounds in total, of which only ~27% have elemental compositions that match those found in the Nature Lipidomics Gateway database (e.g., phosphatidylglycerol (PG), phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidic acid (PA), phosphatidyl serine (PS), and phosphatidylinositol (PI)). The highest phospholipid concentration is found in the epipelagic, which reflects primary production in that depth horizon. Depth-related PL removal was the strongest for PL signals that match database-reported (known) lipids and was lower for saturated non-database (novel) matched PL. The transformation of known PL is marked by depth-related increase in saturation with PA that is assumed to be generated as the earliest transformation product of PL. Novel unsaturated P-lipids likely originate from both PL transformation processes and in-situ biological production at the surface layer. Novel PL are dominated by unsaturated compounds for which unsaturation increased between the epipelagic (average molecular double bond equivalents, DBE = 5) and the abyssopelagic (average DBE = 6.7) zones. Additionally, those compounds increase in both average molecular weight and contribution to all lipid content with increasing depth, likely from cross-linking of unsaturated compounds. Our data indicate that novel PL are selectively preserved with depth and therefore are P and C carriers to the deep Atlantic. We demonstrate that a full appreciation of phosphorus cycling requires additional data on phospholipid composition and especially the ecological role and depth-related molecular change of these compounds.

26046. 题目: A long-term decrease in the persistence of soil carbon caused by ancient Maya land use
文章编号: N18082110
期刊: Nature Geoscience
作者: Peter M. J. Douglas, Mark Pagani, Timothy I. Eglinton, Mark Brenner, Jason H. Curtis, Andy Breckenridge, Kevin Johnston
更新时间: 2018-08-21
摘要: The long-term effects of deforestation on tropical forest soil carbon reservoirs are important for estimating the consequences of land use on the global carbon cycle, but are poorly understood. The Maya Lowlands of Mexico and Guatemala provide a unique opportunity to assess this question, given the widespread deforestation by the ancient Maya that began ~4,000 years ago. Here, we compare radiocarbon ages of plant waxes and macrofossils in sediment cores from three lakes in the Maya Lowlands to record past changes in the mean soil transit time of plant waxes (MTT_wax). MTT_wax indicates the average age of plant waxes that are transported from soils to lake sediments, and comparison of radiocarbon data from soils and lake sediments within the same catchment indicates that MTT_wax reflects the age of carbon in deep soils. All three sediment cores showed a decrease in MTT_wax, ranging from 2,300 to 800 years, over the past 3,500 years. This decrease in MTT_wax, indicating shorter storage times for carbon in lake catchment soils, is associated with evidence for ancient Maya deforestation. MTT_wax never recovered to pre-deforestation values, despite subsequent reforestation, implying that current tropical deforestation will have long-lasting effects on soil carbon sinks.

26047. 题目: Structural features of tundra and taiga soil humic acids according to IR EXPERT analytical system data
文章编号: N18082109
期刊: Journal of Soils and Sediments
作者: Vera D. Tikhova, Yuliya M. Deryabina, Roman S. Vasilevich, Evgeny D. Lodygin
更新时间: 2018-08-21
摘要: Purpose: The purpose of this work is to identify the most probable structural fragments of the tundra and the taiga soil humic acids on the basis of computer analysis of their IR spectra. Materials and methods: Humic acid (HA) samples were isolated from 11 northern soils of the Komi Republic, Russia. IR spectra were registered in KBr by Bruker FTIR spectrometer Vector-22. IR EXPERT information-analytical system was used for analysis of these spectra. This system is a combination of an extensive database (more than 50,000 correlation records of “IR spectrum–structure–structural fragments–accompanying information”) and software modules that allow solving various spectral-structural tasks. Results and discussion: The procedure of working with new IR spectra of humic acid involved two stages. Comparison of the sample IR spectrum with all spectra in IR-EXPERT databases was followed by decomposition of the closest spectral analogs into the set of fragments which is individual for each HA. This unique representation makes it possible to associate a spectrum with a combination of structural fragments rather than with the exact structure. That is what we need for HA. The analysis of the obtained ten-vertex fragments shows that all HA samples contain linear, slightly branched, conjugated chains of double C–C bonds, as well as the fragments of aromatic amines and amides. Conclusions: Using only IR spectroscopy data and the IR EXPERT system, we were able to show that humic acids of these northern soils are predominantly aliphatic and contain a large number of oxygen-containing groups, which allows one to predict their high reactivity when interacting with ecotoxicants.

26048. 题目: Phenol adsorption on biochar prepared from the pine fruit shells: Equilibrium, kinetic and thermodynamics studies
文章编号: N18082108
期刊: Journal of Environmental Management
作者: Noura A.S. Mohammed, Rund A. Abu-Zurayk, Imad Hamadneh, Ammar H. Al-Dujaili
更新时间: 2018-08-21
摘要: Biochar samples were prepared from pine fruit shell (PFS) biomass using slow pyrolysis for 1 h at three different temperatures (350, 450 and 550). Batch experiments were carried out for the biosorption of phenol onto these biochars. The effect of biosorption experimental parameters such as adsorbent dosage, ionic strength, initial solution pH, contact time and temperatures has been investigated. Experimental equilibrium data were fitted to Langmuir, Freundlich, and Dubinin−Radushkevich (D-R) isotherms by non-linear regression method. The experimental kinetic data were also fitted to Lagergren pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models by non-linear regression method. Determination coefficient (R²), chi-squared (χ²) and error function (F_error%) were used to determine the optimum isotherm and kinetic by non-linear regression method. Kinetics results were best described by pseudo-second order model for phenol onto three biochars. Thermodynamic parameters were estimated and implied that the adsorption process is spontaneous and exothermic in nature.
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26049. 题目: Assessment of the use of organic composts derived from municipal solid waste for the adsorption of Pb, Zn and Cd
文章编号: N18082107
期刊: Journal of Environmental Management
作者: Jacqueline Z. Lima, Isabela M. Raimondi, Valdir Schalch, Valéria G.S. Rodrigues
更新时间: 2018-08-21
摘要: Waste management is a continuous global need. To minimize problems arising from municipal solid waste (MSW) disposal, composting has emerged as a simple alternative for the organic fraction of the waste. The composting process generates organic composts with a high metal retention capacity for potentially toxic elements (PTE). Thus, our objective was to examine how different composting methods (windrow composting, wire mesh composting bin, and passively aerated static pile composting) affect the final product, and how the characteristics of the generated composts influence their adsorption capacity for the lead (Pb), zinc (Zn) and cadmium (Cd) elements from mining waste. Therefore, the physical and chemical properties of Brazilian composts were investigated, as well as their adsorption capacities, through batch equilibrium tests with Pb, Zn and Cd in single-element solutions. All composts revealed promising adsorption characteristics, including a near-neutral pH (6.4–7.7); a negative ΔpH (−0.4 to −1.0); oxidizing conditions (Eh between +267.67 and + 347.00 mV); a considerable presence of organic matter (193.92–418.70 g kg⁻¹); a substantial (albeit very varied) cation exchange capacity (29.00–75.00 cmol_c kg⁻¹); and significant porosity (pore volume between 0.01113 and 0.05400 cm³ g⁻¹). These results showed that the composts share similar intrinsic characteristics, indicating that the different composting methods influenced subtly the physical and chemical properties of the final products. Overall, the removal selectivity follows the order Pb > Cd > Zn, with the removal percentage ranging from 94.0 to 99.6% for Pb, 55.4–89.8% for Cd and 22.1–64.0% for Zn. Thus, the joint assessment of the characterization and adsorption results shows evidence that composts, a low-cost organic material produced from waste, may be promising as alternative reactive materials for remediation of soils contaminated by Pb, Zn and Cd.
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26050. 题目: The distribution of and biodegradation impact on spilled oil in sediments from Dalian Bay, NE China
文章编号: N18082106
期刊: Marine Pollution Bulletin
作者: Xiaoguo Yu, Weiyan Zhang, Xing Liu, Jijiang Lei, Zhongsheng Lin, Ziwei Yao, Xuying Yao, Xiaobing Jin, Haili Yang, Haiping Huang
更新时间: 2018-08-21
摘要: Three cores collected in the area of 16th July 2010 oil spill by box crab in May 2013 and July 2014 at the Dalian Bay have been geochemically characterized to investigate the fate of chemical components in sediments. The total organic carbon, extractable organic matter contents and biomarker compositions have been applied for the differentiation of alien organic matters from in situ ones and evaluation of the biodegradation impact. Multivariate statistical analysis suggests four groups of sediments. Except a few samples at deepest part of BQ050, majority samples have certain affinity with the spilled oil. The most contaminated sediments occur at site BQ050 and the spilled oil has migrated to 8–12 cm depth. The degree of contamination can be ranked by the similarity of molecular compositions with spilled oil. Variable biomarker components in sediment extracts were also altered by ongoing biodegradation.

26051. 题目: Marine benthic communities affected by the Doce River (southwestern Atlantic): Baseline before a mining disaster
文章编号: N18082105
期刊: Marine Pollution Bulletin
作者: Helena Matthews-Cascon, Luís Ernesto Arruda Bezerra, Cristiane Xerez Barroso, Soraya Guimarães Rabay, Ana Karla Moreira, Valesca Paula Rocha, Marcelo de Oliveira Soares
更新时间: 2018-08-21
摘要: Prior to Brazil's worst environmental disaster, caused by a mining dam collapse, we had carried out a study of the marine benthic macrofauna (11–51 m depth) under the influence of the Doce River. Our results showed significant diversity, in which mollusks, polychaetes, and crustaceans had the highest frequency, density, and abundance, represented by 162 families in summer and 173 in winter. Our results suggested that richness, abundance, and diversity increase with distance from the coast. Furthermore, with increasing distance from the coast and river mouth, in addition to increasing depth, there was a differentiation in composition and abundance. Multivariate analyses showed depth, carbonate, and organic matter as important factors that explain variations in composition and diversity across the continental shelf. The results could provide an invaluable baseline for measuring the effects on shallow and mesophotic communities of one of the largest tailings dam failures worldwide.

26052. 题目: Effect of different particle-size biochar on methane emissions during pig manure/wheat straw aerobic composting: Insights into pore characterization and microbial mechanisms
文章编号: N18082104
期刊: Bioresource Technology
作者: Xueqin He, Hongjie Yin, Xiaoxi Sun, Lujia Han, Guangqun Huang
更新时间: 2018-08-21
摘要: This study explored the effects of different particle sizes of rice straw biochar (RSB) on the methane emissions of pig manure/wheat straw aerobic composting experiments to provide a theoretical suggestion for biochar application. The experiments were conducted with a control group, powder (<1 mm) group, and granular (4 mm–1 cm) group. Methane emissions increased by 56.84% in the powder group but decreased by 22.15% in the granular group during the aerobic composting. Methane was generated by methanogens and methanotrophs in the specific anaerobic micro-environment characterized by X-ray micro-computed tomography (micro-CT). The porosity of initial composting samples increased by 4.02% in the granular group but decreased by 3.88% in the powder group. RSB additives typically reduced the mcrA/pmoA ratio and increased the diversity of Bacteria and Archaea. Conclusively, granular biochar benefits to aerobic composting to alleviate the CH₄ emissions.
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26053. 题目: Main drivers of transparent exopolymer particle distribution across the surface Atlantic Ocean
文章编号: N18082103
期刊: Biogeosciences
作者: Marina Zamanillo, Eva Ortega-Retuerta, Sdena Nunes, Pablo Rodríguez-Ros, Marta Estrada, María Montserrat Sala, and Rafel Simó
更新时间: 2018-08-21
摘要: Transparent exopolymer particles (TEP) are a class of gel particles produced mainly by microorganisms. TEP play an important role in the ocean carbon cycle, affect sea–air gas exchange and contribute to organic aerosols. The first step to evaluate the TEP influence in these processes is the prediction of TEP occurrence in the ocean. Yet, little is known about the physical and biological variables that control their abundance, particularly in the open ocean. Here we describe horizontal TEP distribution in the surface waters along a North–South transect in the Atlantic Ocean during October–November 2014. Physical and biological variables were run in parallel. Two main regions were separated due to remarkable differences; the open Atlantic Ocean (OAO, n=30), and the Southwestern Atlantic Shelf (SWAS, n=10). TEP concentration in the entire transect ranged from 18.3 to 446.8µg XGeqL⁻¹ and averaged 117.1±119.8µg XGeqL⁻¹, with the maximum concentrations in the edge of the Canary Coastal Upwelling (CU, n=1) and the SWAS, but with the highest TEP to chlorophyll a (TEP:Chl a) ratios at the OAO (CU excluded, average 183±56) and CU (1760.4). TEP were significantly and positively related to Chl a and phytoplankton biomass, expressed in terms of C, along the entire transect. In the OAO, TEP were positively related to some phytoplankton groups, mainly to Synechococcus, and negatively related to the previous 24–hours averaged solar radiation, suggesting the predominance of TEP breaking above the induction of TEP production by UV radiation. Multiple regression analyses showed the combined positive effect of phytoplankton and heterotrophic prokaryotes (HP) on TEP distribution in this region. In the SWAS, TEP were positively related to high nucleic acid prokaryotic cells (HNA) and total phytoplankton biomass, but not with any particular phytoplankton group. TEP constituted an important portion of the particulate organic carbon (POC) pool in the entire transect (28.1–109.8%), and was generally higher than the phytoplankton and HP fraction, highlighting the importance of TEP in the cycle of organic matter in the ocean.

26054. 题目: Characterization of chromophoric dissolved organic matter in lakes on the Tibet Plateau, China, using spectroscopic analysis
文章编号: N18082102
期刊: Biogeosciences
作者: Kaishan Song, Sijia Li, Zhidan Wen, Lili Lyu, and Yingxin Shang
更新时间: 2018-08-21
摘要: Spatiotemporal variations in the characteristics of fluorescent dissolved organic matter (FDOM) components from 63 lakes across the Tibet Plateau, China, are examined using excitation-emission matrix spectra (EEM) and fluorescence regional integration (FRI) from 2014 to 2017. Freshwater (N=135) and brackish water (N=109) samples from 63 lakes were grouped according to salinity or electrical conductivity. In order to compare results between the lakes, cumulative volumes beneath the EEM values (φ_i, i=I, II, III, IV, V) were normalized to a DOC concentration of 1 mg/L. EEM-FRI identified tyrosine-like (φ_I), tryptophan-like (φ_II), fulvic-like (φ_III), microbial protein-like (φ_IV), and humic-like (φ_V) fluorescence regions, as well as their proportions (P_i). Chromophoric dissolved organic matter (CDOM) absorption parameters, fluorescence indices, average fluorescence intensities of the five fluorescent components and total fluorescence intensities (φ_T) differed under spatial variation among brackish and freshwater lakes (ANOVA, p<0.05). Principal component analysis (PCA) was used to assess and group five normalized FDOM components for all of the water samples. These results show that microbial protein-like (φ_IV), fulvic-like (φ_III) and humic-like (φ_V) have positive correlations (R²>0.79, t-test, p<0.01), indicating that these FDOM components may originate from similar sources. A correlation also exists between normalized φ_i (i=I, II, III, IV, V) and DOC concentrations with a salinity >19‰ (averaged EC, 23764μscm⁻¹) (t-test, p<0.01), of which R² f regression analysis showed a decreasing tendency with EC. Similar correlations between a(254) and DOC concentrations (t-test, p<0.01) are also evident for sunshine hours>2900h. Redundancy analysis (RDA) indicates that a(254) and a(350) have a correlation with CDOM in brackish lakes. a(254), HIX and a(350) were also correlated with water quality. Strong evapoconcentration, intense ultraviolet irradiance and landscape features of the Tibet Plateau may be responsible for the FDOM characteristics identified in this study.

26055. 题目: Geochemical, palynological and organic matter characteristics of the Upper Triassic Bagong Formation from the North Qiangtang Basin, Tibetan Plateau
文章编号: N18082101
期刊: Palaeogeography, Palaeoclimatology, Palaeoecology
作者: Fei Yu, Xiugen Fu, Guang Xu, Zhongwei Wang, Wenbin Chen, Shengqiang Zeng, Chunyan Song, Xinglei Feng, Youli Wan, Xueren Li
更新时间: 2018-08-21
摘要: The Upper Triassic Bagong mudstones are considered to be the most significant source rocks in the eastern part of North Qiangtang Basin, Tibetan Plateau. This study investigates the vertical variation of total organic carbon (TOC) contents as well as mineral compositions, carbon isotope, palynology, major and trace element concentrations of the Upper Triassic sediments from Geladandong area of North Qiangtang Basin to understand the mechanism of organic matter accumulation. The TOC concentrations of Bagong Formation mudstone range from 0.77 to 1.37% (mean 1.04%), while the Boni La Formation micritic limestone displays lower TOC contents (0.18–0.37%, average 0.26%). Terrigenous flux proxies including Al, Si, Ti, Th, and Zr concentrations suggest that relatively high detrital flows originate from aluminosilicate compositions during the Upper Triassic sediment deposition. The paleoredox indicators (Mo_EF/U_EF and C_org/P) reflect an oxic-suboxic condition during deposition of the Bagong mudstones and Boni La micritic limestones. The correlation between TOC and P_org and Ba_bio indicates that the Upper Triassic Bagong mudstone has a higher primary productivity compared with most of the Boni La micritic limestone. The palynological investigation and climate proxy (B/Ga and illite/smectite) reflect warm and humid to hot and sub-humid climate condition during the Bagong mudstone deposition. The warm and humid climate condition is favorable for the survival of organisms, which in turn would enhance the primary productivity of surface water. Relatively high primary productivity is the main factor for the organic carbon accumulation in the Upper Triassic Bagong mudstones. In addition, the relatively fast sedimentation rate resulting in preservation a high TOC content of Bagong mudstone deposit in an oxic-suboxic condition. The low primary productivity and the high carbonate production lead to the dilution of organic matter with respect to the low TOC content of Boni La micritic limestone.

26056. 题目: Enhanced global primary production by biogenic aerosol via diffuse radiation fertilization
文章编号: N18082003
期刊: Nature Geoscience
作者: A. Rap, C. E. Scott, C. L. Reddington, L. Mercado, R. J. Ellis, S. Garraway, M. J. Evans, D. J. Beerling, A. R. MacKenzie, C. N. Hewitt, D. V. Spracklen
更新时间: 2018-08-20
摘要: Terrestrial vegetation releases large quantities of plant volatiles into the atmosphere that can then oxidize to form secondary organic aerosol. These particles affect plant productivity through the diffuse radiation fertilization effect by altering the balance between direct and diffuse radiation reaching the Earth’s surface. Here, using a suite of models describing relevant coupled components of the Earth system, we quantify the impacts of biogenic secondary organic aerosol on plant photosynthesis through this fertilization effect. We show that this leads to a net primary productivity enhancement of 1.23 Pg C yr−1 (range 0.76–1.61 Pg C yr−1 due to uncertainty in biogenic secondary organic aerosol formation). Notably, this productivity enhancement is twice the mass of biogenic volatile organic compound emissions (and ~30 times larger than the mass of carbon in biogenic secondary organic aerosol) causing it. Hence, our simulations indicate that there is a strong positive ecosystem feedback between biogenic volatile organic compound emissions and plant productivity through plant-canopy light-use efficiency. We estimate a gain of 1.07 in global biogenic volatile organic compound emissions resulting from this feedback.

26057. 题目: The effect of land use in the catchment and meteorological conditions on the riverine transport of dissolved organic carbon into the Puck Lagoon (southern Baltic)
文章编号: N18082002
期刊: Environmental Monitoring and Assessment
作者: Dominika Saniewska, Karolina Gębka, Katarzyna Łukawska-Matuszewska, Magdalena Bełdowska, Agnieszka Wochna
更新时间: 2018-08-20
摘要: Dissolved organic carbon (DOC) concentration and fluxes from four rivers draining the catchment of the Puck Lagoon in southern Baltic are presented. Water samples from rivers and coastal zone close to the rivers’ mouth were collected from April 2015 to March 2017. DOC was measured using high temperature catalytic oxidation with an NDIR detection. DOC concentration in rivers as well as area specific load discharged to the lagoon reflected variations of land use along their course. Area specific load of DOC discharged by rivers with high proportion of forests, meadows, and pastures in the catchment was significantly higher as compared to rivers with catchment dominated by arable land. However, the main controlling factor of the total discharged loads of DOC was the water flow. The highest loads were observed during the downpour. That was due to the larger volumes of water transported with rivers and the higher concentration of DOC resulting from increased leaching from the catchment area. The obtained results are especially important in the light of climate change in the southern Baltic region. According to the forecasts, we can expect increased precipitation and flooding and consequently increased leaching from the catchment and transport of DOC to the sea via rivers.

26058. 题目: The export flux of particulate organic carbon derived from 210Po / 210Pb disequilibria along the North Atlantic GEOTRACES GA01 (GEOVIDE) transect
文章编号: N18082001
期刊: Biogeosciences
作者: Yi Tang, Nolwenn Lemaitre, Maxi Castrillejo, Montserrat Roca-Martí, Pere Masqué, and Gillian Stewart
更新时间: 2018-08-20
摘要: The disequilibrium between ²¹⁰Po activity and ²¹⁰Pb activity in seawater samples was determined along the GEOTRACES GA01 transect in the North Atlantic during the GEOVIDE cruise (May–June 2014). A steady-state model was used to quantify vertical export of particulate ²¹⁰Po. The deficits of ²¹⁰Po in the Iberian Basin and at the Greenland Shelf were strongly affected by vertical advection. Using the export flux of ²¹⁰Po and the particulate organic carbon (POC) to ²¹⁰Po ratio on total (>1µm) particles, we determined the POC export fluxes along the transect. Both the magnitude and efficiency of the estimated POC export flux from the surface ocean varied spatially within our study region. Export fluxes of POC ranged from negligible to 10mmolCm⁻²d⁻¹, with enhanced POC export in the Labrador Sea. The cruise track was characterized by overall low POC export relative to net primary production (export efficiency<1–15%); but relatively high export efficiencies were seen in the basins where diatoms dominated the phytoplankton community. The particularly low export efficiencies in the Iberian Basin, on the other hand, were explained by the dominance of smaller phytoplankton, in particular, coccolithophores. POC fluxes estimated from the ²¹⁰Po/²¹⁰Pb and ²³⁴Th/²³⁸U disequilibria agreed within a factor of 3 along the transect, with higher POC estimates generally derived from ²³⁴Th. The differences were attributed to integration timescales and the history of bloom events.

26059. 题目: Floating wetlands: an innovative tool for wastewater treatment
文章编号: N18081906
期刊: CLEAN - Soil, Air, Water
作者: Munazzam Jawad Shahid, Muhammad Arslan, Shafaqat Ali, Muhammad Siddique, Muhammad Afzal
更新时间: 2018-08-19
摘要: Floating treatment wetland (FTW) is an effective, and sustainable technology for wastewater treatment. It has been widely adopted for treating various kinds of polluted water including agricultural runoff, stormwater, industrial effluents, etc. In FTWs, plants are vegetated on a floating mat while their roots are extended down to the contaminated water acting as biological filters. Nutrients and potentially toxic metal(s)/element(s) are taken up from the wastewater by plants through their roots whereas organic matter is degraded by the microorganisms forming biofilms on the roots and mat surface. Additionally, organic contaminants which are already taken up by the plants are degraded by endophytic bacteria in planta. This article provides an overview of FTWs and its application for wastewater treatment. The key factors which have an impact on the performance of FTWs are also described. Lastly, potential role of combined use of plants and bacteria in FTWs for the maximum remediation of polluted water is emphasized.

26060. 题目: Warming enhances sedimentation and decomposition of organic carbon in shallow macrophyte-dominated systems with zero net effect on carbon burial
文章编号: N18081905
期刊: Global Change Biology
作者: Mandy Velthuis, Sarian Kosten, Ralf Aben, Garabet Kazanjian, Sabine Hilt, Edwin T. H. M. Peeters, Ellen van Donk, Elisabeth S. Bakker
更新时间: 2018-08-19
摘要: Temperatures have been rising throughout recent decades and are predicted to rise further in the coming century. Global warming affects carbon cycling in freshwater ecosystems, which both emit and bury substantial amounts of carbon on a global scale. Currently, most studies focus on the effect of warming on overall carbon emissions from freshwater ecosystems, while net effects on carbon budgets may strongly depend on burial in sediments. Here, we tested whether year‐round warming increases the production, sedimentation, or decomposition of particulate organic carbon and eventually alters the carbon burial in a typical shallow freshwater system. We performed an indoor experiment in eight mesocosms dominated by the common submerged aquatic plant Myriophyllum spicatum testing two temperature treatments: a temperate seasonal temperature control and a warmed (+4°C) treatment (n = 4). During a full experimental year, the carbon stock in plant biomass, dissolved organic carbon in the water column, sedimented organic matter, and decomposition of plant detritus were measured. Our results showed that year‐round warming nearly doubled the final carbon stock in plant biomass from 6.9 ± 1.1 g C in the control treatment to 12.8 ± 0.6 g C (mean ± SE), mainly due to a prolonged growing season in autumn. DOC concentrations did not differ between the treatments, but organic carbon sedimentation increased by 60% from 96 ± 9.6 to 152 ± 16 g C m⁻² year⁻¹ (mean ± SE) from control to warm treatments. Enhanced decomposition of plant detritus in the warm treatment, however, compensated for the increased sedimentation. As a result, net carbon burial was 40 ± 5.7 g C m⁻² year⁻¹ in both temperature treatments when fluxes were combined into a carbon budget model. These results indicate that warming can increase the turnover of organic carbon in shallow macrophyte‐dominated systems, while not necessarily affecting net carbon burial on a system scale.