40 CFR 98.247 - Records that must be retained.

Code of Federal Regulations, 2011 CFR

2011-07-01

....246(b), and records of any annual average HHV calculations. (b) If you comply with the mass balance... in accordance with § 98.243(c)(4). (2) Start and end times and calculated carbon contents for time....243(c)(4) for determining carbon content of feedstock or product. (3) A part of the monitoring plan...

A Database and Synthesis of Northern Peatland Soil Properties and Holocene Carbon and Nitrogen Accumulation

NASA Technical Reports Server (NTRS)

Loisel, Julie; Yu, Zicheng; Beilman, David W.; Camill, Philip; Alm, Jukka; Amesbury, Matthew J.; Anderson, David; Andersson, Sofia; Bochicchio, Christopher; Barber, Keith;

[Distribution of soil organic carbon storage and carbon density in Gahai Wetland ecosystem].

PubMed

Ma, Wei-Wei; Wang, Hui; Huang, Rong; Li, Jun-Zhen; Li, De-Yu

2014-03-01

The profile distribution and accumulation characteristics of organic carbon of four typical marshes (herbaceous peat, marsh wetland, mountain wetland, subalpine meadow) were studied in Gahai Wetlands of Gannan in July 2011. The results showed that the soil bulk densities of the four typical marshes ranged from 0.22 to 1.29 g x cm(-3). The content of soil organic carbon in the herbaceous peat was higher than in other types, with its average content of organic carbon (286. 80 g x kg(-1)) being about 2.91, 4.99, 7.31 times as much as that of the marsh wetland, mountain wetland and subalpine meadow, respectively. The average organic carbon densities were in order of herbaceous peat > subalpine meadow > marsh wetland > mountain wetland, with the highest in the 0-10 cm layer. The change of organic carbon density along the soil profile was basically in accordance with the organic carbon content in the four typical marshes, but fluctuated with soil depth. There were obviously two carbon storage layers (0-10 and 20-40 cm, respectively) in the four typical marshes. The amounts of organic carbon stored in the 0-60 cm layer of the four typical marshes were 369.46, 278.83, 276.16, 292.23 t x hm(-2), respectively. The total amount of organic carbon stored in the 0-60 cm of the four typical marshes was about 9.50 x 10(6) t.

[Correlation Among Soil Organic Carbon, Soil Inorganic Carbon and the Environmental Factors in a Typical Oasis in the Southern Edge of the Tarim Basin].

PubMed

Gong, Lu; Zhu, Mei-ling; Liu, Zeng-yuan; Zhang, Xue-ni; Xie, Li-na

2016-04-15

We analyzed the differentiation among the environmental factors and soil organic/inorganic carbon contents of irrigated desert soil, brown desert soil, saline soil and aeolian sandy soil by classical statistics methods, and studied the correlation between soil carbon contents and the environmental factor by redundancy analysis (RDA) in a typical oasis of Yutian in the southern edge of the Tarim Basin. The results showed that the average contents of soil organic carbon and soil inorganic carbon were 2.51 g · kg⁻¹ and 25.63 g · kg⁻¹ respectively. The soil organic carbon content of the irrigated desert soil was significantly higher than those of brown desert soil, saline soil and aeolian sandy soil, while the inorganic carbon content of aeolian sandy soil was significantly higher than those of other soil types. The soil moisture and nutrient content were the highest in the irrigated desert soil and the lowest in the aeolian sandy sail. All soil types had high degree of salinization except the irrigated desert soil. The RDA results showed that the impacts of environmental factors on soil carbon contents ranked in order of importance were total nitrogen > available phosphorus > soil moisture > ground water depth > available potassium > pH > total salt. The soil carbon contents correlated extremely significantly with total nitrogen, available phosphorus, soil moisture and ground water depth (P < 0.01), and it correlated significantly with available potassium and pH (P < 0.05). There was no significant correlation between soil carbon contents and other environmental factors (P > 0.05).

40 CFR 98.187 - Records that must be retained.

Code of Federal Regulations, 2013 CFR

2013-07-01

... carbon mass balance procedure is used to determine process CO2 emissions according to the requirements in... subpart (tons). (5) Average carbon content determined and records of the supplier provided information or... of how company records of measurements are used to estimate the carbon input to each smelting furnace...

40 CFR 98.187 - Records that must be retained.

Code of Federal Regulations, 2014 CFR

2014-07-01

... carbon mass balance procedure is used to determine process CO2 emissions according to the requirements in... subpart (tons). (5) Average carbon content determined and records of the supplier provided information or... of how company records of measurements are used to estimate the carbon input to each smelting furnace...

40 CFR 98.187 - Records that must be retained.

Code of Federal Regulations, 2010 CFR

2010-07-01

... carbon mass balance procedure is used to determine process CO2 emissions according to the requirements in... subpart (tons). (5) Average carbon content determined and records of the supplier provided information or... of how company records of measurements are used to estimate the carbon input to each smelting furnace...

40 CFR 98.187 - Records that must be retained.

Code of Federal Regulations, 2012 CFR

2012-07-01

... carbon mass balance procedure is used to determine process CO2 emissions according to the requirements in... subpart (tons). (5) Average carbon content determined and records of the supplier provided information or... of how company records of measurements are used to estimate the carbon input to each smelting furnace...

40 CFR 98.187 - Records that must be retained.

Code of Federal Regulations, 2011 CFR

2011-07-01

... carbon mass balance procedure is used to determine process CO2 emissions according to the requirements in... subpart (tons). (5) Average carbon content determined and records of the supplier provided information or... of how company records of measurements are used to estimate the carbon input to each smelting furnace...

40 CFR Table A-7 to Subpart A of... - Data Elements That Are Inputs to Emission Equations and for Which the Reporting Deadline Is March...

Code of Federal Regulations, 2012 CFR

2012-07-01

... mass balance equation. K 98.116(b) Only annual production by product from each EAF (No CEMS). K 98.116... carbon content values, molecular weights for gaseous feedstocks, molecular weights for gaseous products... of gas flared, average molecular weight, carbon content of the flare, and molar volume conversion...

Digital Mapping of Soil Organic Carbon Contents and Stocks in Denmark

PubMed Central

Adhikari, Kabindra; Hartemink, Alfred E.; Minasny, Budiman; Bou Kheir, Rania; Greve, Mette B.; Greve, Mogens H.

2014-01-01

Estimation of carbon contents and stocks are important for carbon sequestration, greenhouse gas emissions and national carbon balance inventories. For Denmark, we modeled the vertical distribution of soil organic carbon (SOC) and bulk density, and mapped its spatial distribution at five standard soil depth intervals (0−5, 5−15, 15−30, 30−60 and 60−100 cm) using 18 environmental variables as predictors. SOC distribution was influenced by precipitation, land use, soil type, wetland, elevation, wetness index, and multi-resolution index of valley bottom flatness. The highest average SOC content of 20 g kg−1 was reported for 0−5 cm soil, whereas there was on average 2.2 g SOC kg−1 at 60−100 cm depth. For SOC and bulk density prediction precision decreased with soil depth, and a standard error of 2.8 g kg−1 was found at 60−100 cm soil depth. Average SOC stock for 0−30 cm was 72 t ha−1 and in the top 1 m there was 120 t SOC ha−1. In total, the soils stored approximately 570 Tg C within the top 1 m. The soils under agriculture had the highest amount of carbon (444 Tg) followed by forest and semi-natural vegetation that contributed 11% of the total SOC stock. More than 60% of the total SOC stock was present in Podzols and Luvisols. Compared to previous estimates, our approach is more reliable as we adopted a robust quantification technique and mapped the spatial distribution of SOC stock and prediction uncertainty. The estimation was validated using common statistical indices and the data and high-resolution maps could be used for future soil carbon assessment and inventories. PMID:25137066

Digital mapping of soil organic carbon contents and stocks in Denmark.

PubMed

Adhikari, Kabindra; Hartemink, Alfred E; Minasny, Budiman; Bou Kheir, Rania; Greve, Mette B; Greve, Mogens H

2014-01-01

Estimation of carbon contents and stocks are important for carbon sequestration, greenhouse gas emissions and national carbon balance inventories. For Denmark, we modeled the vertical distribution of soil organic carbon (SOC) and bulk density, and mapped its spatial distribution at five standard soil depth intervals (0-5, 5-15, 15-30, 30-60 and 60-100 cm) using 18 environmental variables as predictors. SOC distribution was influenced by precipitation, land use, soil type, wetland, elevation, wetness index, and multi-resolution index of valley bottom flatness. The highest average SOC content of 20 g kg(-1) was reported for 0-5 cm soil, whereas there was on average 2.2 g SOC kg(-1) at 60-100 cm depth. For SOC and bulk density prediction precision decreased with soil depth, and a standard error of 2.8 g kg(-1) was found at 60-100 cm soil depth. Average SOC stock for 0-30 cm was 72 t ha(-1) and in the top 1 m there was 120 t SOC ha(-1). In total, the soils stored approximately 570 Tg C within the top 1 m. The soils under agriculture had the highest amount of carbon (444 Tg) followed by forest and semi-natural vegetation that contributed 11% of the total SOC stock. More than 60% of the total SOC stock was present in Podzols and Luvisols. Compared to previous estimates, our approach is more reliable as we adopted a robust quantification technique and mapped the spatial distribution of SOC stock and prediction uncertainty. The estimation was validated using common statistical indices and the data and high-resolution maps could be used for future soil carbon assessment and inventories.

Seasonal Dynamics of Soil Labile Organic Carbon and Enzyme Activities in Relation to Vegetation Types in Hangzhou Bay Tidal Flat Wetland

PubMed Central

Shao, Xuexin; Yang, Wenying; Wu, Ming

2015-01-01

Soil labile organic carbon and soil enzymes play important roles in the carbon cycle of coastal wetlands that have high organic carbon accumulation rates. Soils under three vegetations (Phragmites australis, Spartina alterniflora, and Scirpusm mariqueter) as well as bare mudflat in Hangzhou Bay wetland of China were collected seasonally. Seasonal dynamics and correlations of soil labile organic carbon fractions and soil enzyme activities were analyzed. The results showed that there were significant differences among vegetation types in the contents of soil organic carbon (SOC) and dissolved organic carbon (DOC), excepting for that of microbial biomass carbon (MBC). The P. australis soil was with the highest content of both SOC (7.86 g kg-1) and DOC (306 mg kg-1), while the S. mariqueter soil was with the lowest content of SOC (6.83 g kg-1), and the bare mudflat was with the lowest content of DOC (270 mg kg-1). Soil enzyme activities were significantly different among vegetation types except for urease. The P. australis had the highest annual average activity of alkaline phosphomonoesterase (21.4 mg kg-1 h-1), and the S. alterniflora had the highest annual average activities of β-glycosidase (4.10 mg kg-1 h-1) and invertase (9.81mg g-1 24h-1); however, the bare mudflat had the lowest activities of alkaline phosphomonoesterase (16.2 mg kg-1 h-1), β-glycosidase (2.87 mg kg-1 h-1), and invertase (8.02 mg g-1 24h-1). Analysis also showed that the soil labile organic carbon fractions and soil enzyme activities had distinct seasonal dynamics. In addition, the soil MBC content was significantly correlated with the activities of urease and β-glucosidase. The DOC content was significantly correlated with the activities of urease, alkaline phosphomonoesterase, and invertase. The results indicated that vegetation type is an important factor influencing the spatial-temporal variation of soil enzyme activities and labile organic carbon in coastal wetlands. PMID:26560310

Biomass consumption and CO2, CO and main hydrocarbon gas emissions in an Amazonian forest clearing fire

Treesearch

T.G. Soares Neto; J.A. Carvalho J.A.; C.A.G. Veras; E.C. Alvarado; R. Gielow; E.N. Lincoln; T.J. Christian; R.J. Yokelson; J.C. Santos

2009-01-01

Biomass consumption and C02, CO and hydrocarbon gas emissions in an Amazonian forest clearing fire are presented and discussed. The experiment was conducted in the arc of deforestation, near the city of Alta Floresta, state of Mato Grosso, Brazil. The average carbon content of dry biomass was 48 percent and the estimated average moisture content...

40 CFR 98.117 - Records that must be retained.

Code of Federal Regulations, 2014 CFR

2014-07-01

... year. (b) If the carbon mass balance procedure is used to determine CO2 emissions according to the... annual process CO2 emissions (tons). (5) Average carbon content determined and records of the supplier... company records of measurements are used to estimate the carbon input and output to each EAF, including...

40 CFR 98.117 - Records that must be retained.

Code of Federal Regulations, 2012 CFR

2012-07-01

... year. (b) If the carbon mass balance procedure is used to determine CO2 emissions according to the... annual process CO2 emissions (tons). (5) Average carbon content determined and records of the supplier... company records of measurements are used to estimate the carbon input and output to each EAF, including...

40 CFR 98.117 - Records that must be retained.

Code of Federal Regulations, 2013 CFR

2013-07-01

... year. (b) If the carbon mass balance procedure is used to determine CO2 emissions according to the... annual process CO2 emissions (tons). (5) Average carbon content determined and records of the supplier... company records of measurements are used to estimate the carbon input and output to each EAF, including...

40 CFR 98.117 - Records that must be retained.

Code of Federal Regulations, 2011 CFR

2011-07-01

... year. (b) If the carbon mass balance procedure is used to determine CO2 emissions according to the... annual process CO2 emissions (tons). (5) Average carbon content determined and records of the supplier... company records of measurements are used to estimate the carbon input and output to each EAF, including...

The role of Terebralia (Gastropoda: Potamididae) in carbon deposits at mangrove forest Pulau Panjang, Serang-Banten

NASA Astrophysics Data System (ADS)

Patria, Mufti Petala; Putri, Selvianti Asmara

2017-05-01

Research into the role of Terebralia snail in the storage of carbon at mangrove Pulau Panjang was performed from November to December 2013. The mangrove was located in the intertidal part which is affected by a low tide of the sea. When collecting the data, we made 30 quadrants with a 0.25 × 0.25 m size, which was determined at random. The measured data were Terebralia density (T. palustris and T. sulcata) and the carbon content in the whole body. The results of the study showed that Terebralia palustris has the highest density of 25 individual/m2, while Terebralia sulcata has the lowest density of 15 individual/m2. The percentage of carbon content stored in the body of T. palustris ranged from 16.27 to 18.89 % with an average of 17.45%, while the carbon stored in the body of T. sulcata ranged from 15.98 to 17.62 % with an average of 16.87%. Potential carbon storage by T. palustris and T. sulcata was 4374 g C/m2 and 2609 g C/m2, respectively.

Soil carbon stocks along an altitudinal gradient in different land-use categories in Lesser Himalayan foothills of Kashmir

NASA Astrophysics Data System (ADS)

Shaheen, H.; Saeed, Y.; Abbasi, M. K.; Khaliq, A.

2017-04-01

The carbon sequestration potential of soils plays an important role in mitigating the effect of climate change, because soils serve as sinks for atmospheric carbon. The present study was conducted to estimate the carbon stocks and their variation with altitudinal gradient in the Lesser Himalayan foothills of Kashmir. The carbon stocks were estimated in different land use categories, namely: closed canopy forests, open forests, disturbed forests, and agricultural lands within the altitudinal range from 900 to 2500 m. The soil carbon content was determined by the Walkley-Black titration method. The average soil carbon stock was found to be 2.59 kg m-2. The average soil carbon stocks in closed canopy forests, open forests, and disturbed forests were 3.39, 2.06, and 2.86 kg m-2, respectively. The average soil carbon stock in the agricultural soils was 2.03 kg m-2. The carbon stocks showed a significant decreasing trend with the altitudinal gradient with maximum values of 4.13 kg m-2 at 900-1200 m a.s.l. and minimum value of 1.55 kg m-2 at 2100-2400 m a.s.l. The agricultural soil showed the least carbon content values indicating negative impacts of soil plowing, overgrazing, and soil degradation. Lower carbon values at higher altitudes attest to the immature character of forest stands, as well as to degradation due to immense fuel wood extraction, timber extraction, and harsh climatic conditions. The study indicates that immediate attention is required for the conservation of rapidly declining carbon stocks in agricultural soils, as well as in the soils of higher altitudes.

Biomass consumption and CO2, CO and main hydrocarbon gas emissions in an Amazonian forest clearing fire

Treesearch

T. G. Soares Neto; J. A. Carvalho; C. A. G. Veras; E. C. Alvarado; R. Gielow; E. N. Lincoln; T. J. Christian; R. J. Yokelson; J. C. Santos

2009-01-01

Biomass consumption and CO2, CO and hydrocarbon gas emissions in an Amazonian forest clearing fire are presented and discussed. The experiment was conducted in the arc of deforestation, near the city of Alta Floresta, state of Mato Grosso, Brazil. The average carbon content of dry biomass was 48% and the estimated average moisture content of fresh biomass was 42% on...

The moisture response of soil heterotrophic respiration: Interaction with soil properties.

USDA-ARS?s Scientific Manuscript database

Soil moisture-respiration functions are used to simulate the various mechanisms determining the relations between soil moisture content and carbon mineralization. Soil models used in the simulation of global carbon fluxes often apply simplified functions assumed to represent an average moisture-resp...

Clay Chemistry's Influence on the Average Carbon Content and Particle Size at the Ninety-Six Historical Site, South Carolina

NASA Astrophysics Data System (ADS)

Lintz, L.; Werts, S. P.

2014-12-01

The Ninety-Six National Historic Site is located in Greenwood County, SC. Recent geologic mapping of this area has revealed differences in soil properties over short distances within the park. We studied the chemistry of the clay minerals found within the soils to see if there was a correlation between the amounts of soil organic carbon contained in the soil and particle size in individual soil horizons. Three different vegetation areas, including an old field, a deciduous forest, and a pine forest were selected to see what influence vegetation type had on the clay chemistry and carbon levels as well. Four samples containing the O, A, and B horizons were taken from each location and we studied the carbon and nitrogen content using an elemental analyzer, particle size using a Laser Diffraction Particle Size Analyzer, and clay mineralogy with powder X-ray diffraction of each soil sample. Samples from the old field and pine forest gave an overall negative correlation between carbon content and clay percentage, which is against the normal trend for Southern Piedmont Ultisols. The deciduous forest samples gave no correlation at all between its carbon content and clay percentage. Together, all three locations show the same negative relationship, while once separated into vegetation type and A and B horizons it shows even more abnormal relationships of negative while several show no correlation (R2= 0.007403- 0.56268). Using powder XRD, we ran clay samples from each A and B horizon for the clay mineralogy. All three vegetation areas had the same results of containing quartz, kaolinite, and Fe oxides, therefore, clay chemistry is not a reason behind the abnormal trend of a negative correlation between average carbon content and clay percentage. Considering that all three locations have the same climate, topography, and parent material of metagranite, it could be reasonable to assume these results are a factor of environmental and biological influences rather than clay type.

Petrophysical, Lithological and Mineralogical Characteristics of the Shale Strata of the Volga- Ural Region

NASA Astrophysics Data System (ADS)

Morozov, Vladimir P.; Plotnikova, Irina N.; Pronin, Nikita V.; Nosova, Fidania F.; Pronina, Nailya R.

2014-05-01

The objects of the study are Upper Devonian carbonate rocks in the territory of South-Tatar arch and Melekess basin in the Volga- Urals region. We studied core material of Domanicoid facies from the sediments of Mendymski and Domanik horizons of middle substage of Frasnian stage of the Upper Devonian. Basic analytical research methods included the following: study of the composition, structural and textural features of the rocks, the structure of their voids, filter and reservoir properties and composition of the fluid. The complex research consisted of macroscopic description of the core material, optical microscopy analysis, radiographical analysis, thermal analysis, x-ray tomography, electron microscopy, gas-liquid chromatography, chromate-mass spectrometry, light hydrocarbons analysis using paraphase assay, adsorbed gases analysis, and thermal vacuum degassing method. In addition, we performed isotopic studies of hydrocarbons saturating shale rocks. Shale strata are mainly represented by carbonate-chert rocks. They consist mainly of calcite and quartz. The ratio of these rock-forming minerals varies widely - from 25 to 75 percent. Pyrite, muscovite, albite, and microcline are the most common inclusions. Calcareous and ferruginous dolomite (ankerite), as well as magnesian calcite are tracked down as secondary minerals. While performing the tests we found out that the walls of open fractures filled with oil are stacked by secondary dolomite, which should be considered as an indication moveable oil presence in the open-cut. Electron microscopy data indicate that all the studied samples have porosity - both carbonates and carbonate-siliceous rocks. Idiomorphism of the rock-forming grains and pores that are visible under a microscope bring us to that conclusion. The analysis of the images indicates that the type of reservoir is either porous or granular. The pores are distributed evenly in the volume of rock. Their size is very unstable and varies from 0.5 microns to 100 microns. The lowest value are observed in long carbonate-siliceous rocks, the highest values are found in carbonate rocks. The latter is caused by the fact that there is a very strong recrystallization of calcite and its dolomite substitution in carbonates. Open porosity ranges from 0.65 to 7.98 percent, average value is 4.1percent . Effective porosity has an average value of 0.44 percent, ranging from 0.22 to 1.97. Permeability varies from 0.043 to 1.49 mD, average value is 0,191 mD. Organic matter was found in all samples. Its content varies within the section. The fluctuation range of from 1.0 to 20 percent. The lowest content of carbonates is found in carbonates, while the highest is observed in carbonate-siliceous rocks with a high content of chalcedony. Average organic matter content is 5-7 percent. According to Rock-Eval studies of the core, the catagenetic maturity of organic matter corresponds to MK1 - MK2 degree. We found a connection between the type of organic matter and the composition of adsorbed gas. We also could see that the samples with humic organics present in their organic matter and can be characterized by a fair dominance of methane over other gases. There is a clear relationship between organic matter content and the intensity of the gas saturation of the rock. Organic matter is characteristic mainly of the most siliceous formations. In "pure" carbonates, which are represented by micro-layers with different capacities, OM is not observed at all or its content is quite low.

Evaluating the impacts of landscape positions and nitrogen fertilizer rates on dissolved organic carbon on switchgrass land seeded on marginally yielding cropland.

PubMed

Lai, Liming; Kumar, Sandeep; Mbonimpa, Eric G; Hong, Chang Oh; Owens, Vance N; Neupane, Ram P

2016-04-15

Dissolved organic carbon (DOC) through leaching into the soils is another mechanism of net C loss. It plays an important role in impacting the environment and impacted by soil and crop management practices. However, little is known about the impacts of landscape positions and nitrogen (N) fertilizer rates on DOC leaching in switchgrass (Panicum virgatum L.). This experimental design included three N fertilizer rates [0 (low); 56 (medium); 112 (high) kg N ha(-1)] and three landscape positions (shoulder, backslope and footslope). Daily average DOC contents at backslope were significantly lower than that at shoulder and footslope. The DOC contents from the plots that received medium N rate were also significantly lower than the plots that received low N rates. The interactions of landscape and N rates on DOC contents were different in every year from 2009 to 2014, however, no significant consistent trend of DOC contents was observed over time. Annual average DOC contents from the plots managed with low N rate were higher than those with high N rate. These contents at the footslope were higher than that at the shoulder position. Data show that there is a moderate positive relationship between the total average DOC contents and the total average switchgrass biomass yields. Overall, the DOC contents from leachate in the switchgrass land were significantly influenced by landscape positions and N rates. The N fertilization reduced DOC leaching contents in switchgrass field. The switchgrass could retain soil and environment sustainability to some extent. These findings will assist in understanding the mechanism of changes in DOC contents with various parameters in the natural environment and crop management systems. However, use of long-term data might help to better assess the effects of above factors on DOC leaching contents and loss in the switchgrass field in the future. Copyright © 2016 Elsevier Ltd. All rights reserved.

40 CFR 98.243 - Calculating GHG emissions.

Code of Federal Regulations, 2010 CFR

2010-07-01

...) through (b)(3). (c) Mass balance for each petrochemical process unit. Calculate the emissions of CO2 from...). (3) Collect a sample of each feedstock and product at least once per month and determine the carbon... carbon content measurements are made during the monthly measurement period, average them arithmetically...

Soluble and insoluble carbon content in fog: a 16 year long study in the Po Valley (Italy)

NASA Astrophysics Data System (ADS)

Fuzzi, S.; Facchini, C.; Giulianelli, L.; Gilardoni, S.

2015-12-01

Fog samples have been collected throughout the fall-winter season during each dense fog episode since 1989 at the field station of San Pietro Capofiume (Bologna, Italy) located in a rural area in the south-eastern part of the Po Valley. Since the fall-winter season 1997/98 both soluble and insoluble carbon content was also measured and now a sixteen years long dataset is available. Carbonaceous matter accounts for a significant fraction of the insoluble material suspended in fog water. The sum of EC and water insoluble organic mass accounts on average for 46%-56% of the mass of total suspended material. Insoluble carbonaceous material is composed mainly by organic matter, EC accounting on average only for 17% of the total insoluble carbon. A good correlation observed between EC and OC through the different years, suggests that anthropogenic combustion processes, which represent the main source of EC, are also the most important source of OC in fog droplets. Recent results also show that a potential important contribution to WSOC in for water is derived by aqueous secondary organic aerosol from biomass burning emissions. The water soluble organic carbon (WSOC) represents on average 25% of the total solute mass and its contribution to the total organic carbon (TOC) ranges from 52 to 95% with an average of 86%. The high amount of carbonaceous compounds in the Po Valley fog detected and the simultaneous decrease of the main inorganic species concentration (Giulianelli et al., 2014) in the last two decades highlight the potential influence of organics on the decrease of fog frequency. Giulianelli L., Gilardoni S., Tarozzi L., Rinaldi M., Decesari S, Carbone C., Facchini M.C. and Fuzzi S., Atmos. Environ. 98, 394-401.

Carbonate concretions as a significant component of ancient marine carbon cycles: Insights from paired organic and inorganic carbon isotope analyses of a Cretaceous shale

NASA Astrophysics Data System (ADS)

Loyd, S. J.

2014-12-01

Carbonate concretions often occur within fine-grained, organic-rich sedimentary rocks. This association reflects the common production of diagenetic minerals through biologic cycling of organic matter. Chemical analysis of carbonate concretions provides the rare opportunity to explore ancient shallow diagenetic environments, which are inherently transient due to progressive burial but are an integral component of the marine carbon cycle. The late Cretaceous Holz Shale (~80 Ma) contains abundant calcite concretions that exhibit textural and geochemical characteristics indicative of relatively shallow formation (i.e., near the sediment-water interface). Sampled concretions contain between 5.4 and 9.8 wt.% total inorganic carbon (TIC), or ~45 and 82 wt.% CaCO3, compared to host shale values which average ~1.5 wt.% TIC. Organic carbon isotope compositions (δ13Corg) are relatively constant in host and concretion samples ranging from ­-26.3 to -24.0‰ (VPDB). Carbonate carbon isotope compositions (δ13Ccarb) range from -22.5 to -3.4‰, indicating a significant but not entirely organic source of carbon. Concretions of the lower Holz Shale exhibit considerably elevated δ13Ccarb values averaging -4.8‰, whereas upper Holz Shale concretions express an average δ13Ccarb value of -17.0‰. If the remaining carbonate for lower Holz Shale concretions is sourced from marine fluids and/or dissolved marine carbonate minerals (e.g., shells), a simple mass balance indicates that ~28% of concretion carbon was sourced from organic matter and ~72% from late Cretaceous marine inorganic carbon (with δ13C ~ +2.5‰). Upper Holz Shale calculations indicate a ~73% contribution from organic matter and a ~27% contribution from inorganic carbon. When normalized for carbonate, organic contents within the concretions are ~2-13 wt.% enriched compared to host contents. This potentially reflects the protective nature of cementation that acts to limit permeability and chemical destruction of organic material. These data imply that concretion growth in shallow sediments can act as a significant and long-term sink for both marine inorganic and organic carbon.

Progress report on sediment analyses at selected faunal monitoring sites in north-central and northeastern Florida Bay

USGS Publications Warehouse

Scott, T.M.; Means, G.H.; Brewster-Wingard, G. L.

1997-01-01

Florida Bay is a shallow, subtropical lagoon at the southern tip of the Florida peninsula. The 2200 square kilometer, triangular-shaped area is the site of modern carbonate sediment formation and deposition. The intricate ecosystem of the bay has undergone significant changes as the result of natural influences and human intervention. The purpose of this study is to investigate carbonate sediment characteristics and distribution in conjunction with faunal and floral to determine the substrate preferences of associated fauna and flora. The modern data provide the proxy data for down-core analyses of sediments, fauna and flora in order to document ecosystem changes in the bay. Selected sediment samples collected during 1996 from 18 sites in the northeastern and central bay were analyzed for insoluble residues, organic content, total carbonate, and percent of silt and clay sized particles. Insoluble residues range from 0.8% of the sediment in a shell lag to 11.5% with an average of 5.1%. Organic content ranged from a minimum of 1.43% of the sediment to 18.05% with an average of 7.6%. The total carbonate content ranged from 72.56% to 97.81%, averaging 87.98%. The percent silt and clay sized particles ranged from 13.75% to 63.62% for the samples analyzed. The insoluble residue content shows a general trend of decreasing insoluble residues from the northeastern bay toward the southwest. Organic content is variable throughout the bay and does not show a regional trend. Several sites show a trend of higher organic content in the samples collected in February as compared to those collected in July. Lithologic examination indicated that, in addition to the carbonate mud (less than 63mm), sample components included whole and fragmented mollusks, foraminifers, bryozoans, ostracods, and organic matter. The insoluble residues consisted of quartz sand and silt, clays and siliceous fossils. A component of the insoluble residues may be dust derived from Africa and transported to southern Florida by the prevailing winds. This report is preliminary and has not been reviewed for conformity with U.S. Geological Survey editorial standards or with the North American Stratigraphic Code. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Constraining Sources of Subducted and Recycled Carbon Along the Sunda Arc

NASA Astrophysics Data System (ADS)

House, B. M.; Bebout, G. E.; Hilton, D. R.; Rodriguez, B.; Plank, T. A.

2014-12-01

From sediment subduction rates and C contents at ODP/DSDP sites 765 and 211, we estimate the rate of C subduction along ~2000 km of the East Sunda Arc to be ~0.4 Tg C yr-1, representing a significant source of subducted volatiles [1]. However volatile recycling efficiency and the provenance of recycled volatiles in this region remain poorly understood. With new δ13C measurements of both carbonate and organic carbon from sites 211 and 765, we present the most detailed study yet of the spatial variability of subducted C and recycled CO2 provenance along the strike of the arc. Furthermore we demonstrate the importance of oceanic crustal carbonate as a C source in a subduction zone that is otherwise carbonate starved. Carbonate content throughout the sediment column decreases dramatically between site 765, approximately 250 km from the Australian continental margin, and site 211, approximately 300 km southwest of the trench and outboard of the Sunda Strait between Sumatra and Java. Continental and shelf carbonate input from the Australian margin dominates shallow deposits at site 765, but underlying pelagic sediments are thought to contribute the majority of inorganic C to the arc. The paucity of carbonate in sediments at site 211 suggests that along this segment essentially all carbonate subducted is derived from altered ocean crust, presenting an opportunity to study the effects of crustal carbonate input. While previous C provenance studies relied on globally-averaged δ13C values for organic and inorganic C in subducted sediments, we present new estimates based on measured δ13CVPDB of carbonate (average of ~2‰ in subducted sediments) and organic carbon (-22.5 to -23‰ average) along with previously published efflux data [2]. These estimates suggest that the arc-averaged ratio of carbonate to organic C subducted along the East Sunda Arc is nearly identical to the inorganic to organic C ratio represented in volcanic and hydrothermal CO2 output, suggesting that differential devolatilization of carbonate and organic C is limited. Our calculated CO2 recycling efficiency of 10 to 20% - which does not include fore-arc outgassing - agrees with geochemical models predicting up to 80% of subducted C may be carried into the deep mantle [3]. [1] Hilton et al., 2002; [2] Halldórsson et al., 2013; [3] Cook-Kollars et al., 2014

Structural equation modelling reveals factors regulating surface sediment organic carbon content and CO2 efflux in a subtropical mangrove.

PubMed

Ouyang, Xiaoguang; Lee, Shing Yip; Connolly, Rod M

2017-02-01

Mangroves are blue carbon ecosystems that sequester significant carbon but release CO 2 , and to a lesser extent CH 4, from the sediment through oxidation of organic carbon or from overlying water when flooded. Previous studies, e.g. Leopold et al. (2015), have investigated sediment organic carbon (SOC) content and CO 2 flux separately, but could not provide a holistic perspective for both components of blue carbon. Based on field data from a mangrove in southeast Queensland, Australia, we used a structural equation model to elucidate (1) the biotic and abiotic drivers of surface SOC (10cm) and sediment CO 2 flux; (2) the effect of SOC on sediment CO 2 flux; and (3) the covariation among the environmental drivers assessed. Sediment water content, the percentage of fine-grained sediment (<63μm), surface sediment chlorophyll and light condition collectively drive sediment CO 2 flux, explaining 41% of their variation. Sediment water content, the percentage of fine sediment, season, landform setting, mangrove species, sediment salinity and chlorophyll collectively drive surface SOC, explaining 93% of its variance. Sediment water content and the percentage of fine sediment have a negative impact on sediment CO 2 flux but a positive effect on surface SOC content, while sediment chlorophyll is a positive driver of both. Surface SOC was significantly higher in Avicennia marina (2994±186gm -2 , mean±SD) than in Rhizophora stylosa (2383±209gm -2 ). SOC was significantly higher in winter (2771±192gm -2 ) than in summer (2599±211gm -2 ). SOC significantly increased from creek-side (865±89gm -2 ) through mid (3298±137gm -2 ) to landward (3933±138gm -2 ) locations. Sediment salinity was a positive driver of SOC. Sediment CO 2 flux without the influence of biogenic structures (crab burrows, aerial roots) averaged 15.4mmolm -2 d -1 in A. marina stands under dark conditions, lower than the global average dark flux (61mmolm -2 d -1 ) for mangroves. Copyright © 2016 Elsevier B.V. All rights reserved.

Heterogeneity in mantle carbon content from CO2-undersaturated basalts

PubMed Central

Le Voyer, M.; Kelley, K.A.; Cottrell, E.; Hauri, E.H.

2017-01-01

The amount of carbon present in Earth's mantle affects the dynamics of melting, volcanic eruption style and the evolution of Earth's atmosphere via planetary outgassing. Mantle carbon concentrations are difficult to quantify because most magmas are strongly degassed upon eruption. Here we report undegassed carbon concentrations from a new set of olivine-hosted melt inclusions from the Mid-Atlantic Ridge. We use the correlations of CO2 with trace elements to define an average carbon abundance for the upper mantle. Our results indicate that the upper mantle carbon content is highly heterogeneous, varying by almost two orders of magnitude globally, with the potential to produce large geographic variations in melt fraction below the volatile-free solidus. Such heterogeneity will manifest as variations in the depths at which melt becomes interconnected and detectable, the CO2 fluxes at mid-ocean ridges, the depth of the lithosphere-asthenosphere boundary, and mantle conductivity. PMID:28082738

Remarkable activity of nitrogen-doped hollow carbon spheres encapsulated Cu on synthesis of dimethyl carbonate: Role of effective nitrogen

NASA Astrophysics Data System (ADS)

Li, Haixia; Zhao, Jinxian; Shi, Ruina; Hao, Panpan; Liu, Shusen; Li, Zhong; Ren, Jun

2018-04-01

A critical aspect in the improvement of the catalytic performance of Cu-based catalysts for the synthesis of dimethyl carbonate (DMC) is the development of an appropriate support. In this work, nitrogen-doped hollow carbon spheres (NHCSs), with 240 nm average diameter, 17 nm shell thickness, uniform mesoporous structure and a specific surface area of 611 m2 g-1, were prepared via a two-step Stӧber method. By varying the quantity of nitrogen-containing phenols used in the preparation it has been possible to control the nitrogen content and, consequently, the sphericity of the NHCSs. It was found that perfect spheres were obtained for nitrogen contents below 5.4 wt.%. The catalysts (Cu@NHCSs) were prepared by the hydrothermal impregnation method. The catalytic activity towards DMC synthesis was notably enhanced due to the immobilization effect on Cu particles and the enhanced electron transfer effect exercised by the effective nitrogen species, including pyridinic-N and graphitic-N. When the average size of the copper nanoparticles was 7.4 nm and the nitrogen content was 4.0 wt.%, the values of space-time yield of DMC and of turnover frequency (TOF) reached 1528 mg/(g h) and 11.0 h-1, respectively. The TOF value of Cu@NHCSs was 6 times higher than non-doped Cu@Carbon (2.1 h-1). The present work introduces the potential application of nitrogen-doped carbon materials and presents a novel procedure for the preparation of catalysts for DMC synthesis.

Calcium content of different compositions of gallstones and pathogenesis of calcium carbonate gallstones.

PubMed

Yu, Ji-Kuen; Pan, Huichin; Huang, Shing-Moo; Huang, Nan-Lan; Yao, Chung-Chin; Hsiao, Kuang-Ming; Wu, Chew-Wun

2013-01-01

Our aim was to investigate the calcium content of different gallstone compositions and the pathogenic mechanisms of calcium carbonate gallstones. Between August 2001 and July 2007, gallstones from 481 patients, including 68 calcium carbonate gallstones, were analyzed for total calcium content. Gallbladder bile samples from 33 cases and six controls were analyzed for pH, carbonate anion level, free-ionized calcium concentration and saturation index for calcium carbonate. Total calcium content averaged 75.6 %, 11.8 %, and 4.2 % for calcium carbonate, calcium bilirubinate and cholesterol gallstones. In 29.4 % of patients, chronic and/or intermittent cystic duct obstructions were caused by polypoid lesions in the neck region and 70.6 % were caused by stones. A total of 82 % of patients had chronic low-grade inflammation of the gallbladder wall and 18.0 % had acute inflammatory exacerbations. In the bile, we found the mean pH, mean carbonate anion, free-ionized calcium concentrations, and mean saturation index for calcium carbonate to be elevated in comparison to controls. From our study, we found chronic and/or intermittent cystic duct obstructions and low-grade GB wall inflammation lead to GB epithelium hydrogen secretion dysfunction. Increased calcium ion efflux into the GB lumen combined with increased carbonate anion presence increases SI_CaCO(3) from 1 to 22.4. Thus, in an alkaline milieu with pH 7.8, calcium carbonate begins to aggregate and precipitate. Copyright © 2012. Published by Elsevier B.V.

40 CFR 98.335 - Procedures for estimating missing data.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 21 2011-07-01 2011-07-01 false Procedures for estimating missing data... missing data. For the carbon input procedure in § 98.333(b), a complete record of all measured parameters... average carbon contents of inputs according to the procedures in § 98.335(b) if data are missing. (b) For...

40 CFR 98.335 - Procedures for estimating missing data.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 22 2013-07-01 2013-07-01 false Procedures for estimating missing data... missing data. For the carbon input procedure in § 98.333(b), a complete record of all measured parameters... average carbon contents of inputs according to the procedures in § 98.335(b) if data are missing. (b) For...

40 CFR 98.335 - Procedures for estimating missing data.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 21 2014-07-01 2014-07-01 false Procedures for estimating missing data... missing data. For the carbon input procedure in § 98.333(b), a complete record of all measured parameters... average carbon contents of inputs according to the procedures in § 98.335(b) if data are missing. (b) For...

40 CFR 98.335 - Procedures for estimating missing data.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 22 2012-07-01 2012-07-01 false Procedures for estimating missing data... missing data. For the carbon input procedure in § 98.333(b), a complete record of all measured parameters... average carbon contents of inputs according to the procedures in § 98.335(b) if data are missing. (b) For...

40 CFR 98.335 - Procedures for estimating missing data.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Procedures for estimating missing data... missing data. For the carbon input procedure in § 98.333(b), a complete record of all measured parameters... average carbon contents of inputs according to the procedures in § 98.335(b) if data are missing. (b) For...

Preignition and Autoignition Behavior of the Xylene Isomers

DTIC Science & Technology

2010-03-01

3 β-scission is the breaking of the carbon-carbon bond at the carbon atom one removed from the radical site (Law, 2006). 10...jet fuel (TS-1); this sample matches the average paraffin, naphthene , and aromatic content of jet fuel samples fairly well (Holley et al., 2007). A...Moreover, Lenhert et al. (2009) identified phenol as an intermediate from toluene oxidation in the PFR facility. This also removes concern that phenol may

Remote Sensing of Vegetation Nitrogen Content for Spatially Explicit Carbon and Water Cycle Estimation

NASA Astrophysics Data System (ADS)

Zhang, Y. L.; Miller, J. R.; Chen, J. M.

2009-05-01

Foliage nitrogen concentration is a determinant of photosynthetic capacity of leaves, thereby an important input to ecological models for estimating terrestrial carbon and water budgets. Recently, spectrally continuous airborne hyperspectral remote sensing imagery has proven to be useful for retrieving an important related parameter, total chlorophyll content at both leaf and canopy scales. Thus remote sensing of vegetation biochemical parameters has promising potential for improving the prediction of global carbon and water balance patterns. In this research, we explored the feasibility of estimating leaf nitrogen content using hyperspectral remote sensing data for spatially explicit estimation of carbon and water budgets. Multi-year measurements of leaf biochemical contents of seven major boreal forest species were carried out in northeastern Ontario, Canada. The variation of leaf chlorophyll and nitrogen content in response to various growth conditions, and the relationship between them,were investigated. Despite differences in plant type (deciduous and evergreen), leaf age, stand growth conditions and developmental stages, leaf nitrogen content was strongly correlated with leaf chlorophyll content on a mass basis during the active growing season (r2=0.78). With this general correlation, leaf nitrogen content was estimated from leaf chlorophyll content at an accuracy of RMSE=2.2 mg/g, equivalent to 20.5% of the average measured leaf nitrogen content. Based on this correlation and a hyperspectral remote sensing algorithm for leaf chlorophyll content retrieval, the spatial variation of leaf nitrogen content was inferred from the airborne hyperspectral remote sensing imagery acquired by Compact Airborne Spectrographic Imager (CASI). A process-based ecological model Boreal Ecosystem Productivity Simulator (BEPS) was used for estimating terrestrial carbon and water budgets. In contrast to the scenario with leaf nitrogen content assigned as a constant value without differentiation between and within vegetation types for calculating the photosynthesis rate, we incorporated the spatial distribution of leaf nitrogen content in the model to estimate net primary productivity and evaportranspiration of boreal ecosystem. These regional estimates of carbon and water budgets with and without N mapping are compared, and the importance of this leaf biochemistry information derived from hyperspectral remote sensing in regional mapping of carbon and water fluxes is quantitatively assessed. Keywords: Remote Sensing, Leaf Nitrogen Content, Spatial Distribution, Carbon and Water Budgets, Estimation

Geology, coal resources, and chemical analyses of coal from the Fruitland Formation, Kimbeto EMRIA study site, San Juan County, New Mexico

USGS Publications Warehouse

Schneider, Gary B.; Hildebrand, Rick T.; Affolter, Ronald H.

1979-01-01

The Kimbeto EMRIA study site, an area of about 20 square miles (52 km2), is located on the south margin of the San Juan Basin on the gently northward-dipping strata of the Upper Cretaceous Fruitland Formation and the Kirtland Shale. The coal beds are mainly in the lower 150 feet (45 m) of the Fruitland Format ion. Coal resources--measured, indicated, and inferred--with less than 400 feet (120 m) of overburden in the site are 69,085,000 short tons (62,660,100 metric tons), 369,078,000 short tons (334,754,000 metric tons), and 177,803,000 short tons (161,267,000 metric tons) respectively. About 68 percent of these resources are overlain by 200 feet (60 m) or less of overburden. The apparent rank of the coal ranges from subbituminous B to subbituminous A. The average Btu/lb value of 14 core samples from the site on the as-received basis is 8,240 (4580 Kcal/kg), average ash content is 23.4 percent, and average sulfur content is 0.5 percent. Analyses of coal from the Kimbeto EMRIA study site show significantly higher ash content and significantly lower contents of volatile matter, fixed carbon, carbon, and a significantly lower heat of combustion when compared with other coal analyses from the Rocky Mountain province.

Carbon budgets of thirteen years at the FLUXNET cropland site Oensingen, Switzerland

NASA Astrophysics Data System (ADS)

Emmel, Carmen; Revill, Andrew; Hörtnagl, Lukas; Eugster, Werner

2017-04-01

The FLUXNET cropland site at Oensingen, Switzerland (CH-Oe2) is located on the Swiss Plateau, which is representative for the average domain of agricultural crop production in Switzerland. The site is managed under the low pesticide integrated production (IP) farming protocol and features a crop rotation focusing on winter wheat, but also includes winter barley, rapeseed, peas and potatoes as well as intermediate cover crops. Thirteen years of eddy covariance and meteorological measurements are available for the site. The carbon imports through manure applications and sowing, along with the exports through harvests, were quantified. In this study, we analyze the carbon budgets of all crop types and measurement years. These results will be compared to changes in soil carbon content. We will answer the questions: (1) Has the crop rotation and field management resulted in a net carbon source or sink? (2) To what extent are the different crop types linked to net carbon exchanges? (3) What are the climatic potential drivers for the interannual cropland carbon budget? (4) Is the carbon budget reflected in the changes in soil carbon content?

Structural characterization of graphene layers in various Indian coals by X-Ray Diffraction technique

NASA Astrophysics Data System (ADS)

Manoj, B.; Kunjomana, A. G.

2015-02-01

The results of the structural investigation of three Indian coals showed that, the structural parameters like fa & Lc increased where as interlayer spacing d002 decreased with increase in carbon content, aromaticity and coal rank. These structural parameters change just opposite with increase in volatile matter content. Considering the 'turbostratic' structure for coals, the minimum separation between aromatic lamellae was found to vary between 3.34 to 3.61 A° for these coals. As the aromaticity increased, the interlayer spacing decreased an indication of more graphitization of the sample. Volatile matter and carbon content had a strong influence on the aromaticity, interlayer spacing and stacking height on the sample. The average number of carbon atoms per aromatic lamellae and number of layers in the lamellae was found to be 16-21 and 7-8 for all the samples.

Alkanes in fungal spores.

PubMed

Oró, J; Laseter, J L; Weber, D

1966-10-21

The chlamydospores of Ustilago maydis, U. nuda, and Sphacelotheca reiliana were analyzed by gas chromatography and mass spectrometry for their hydrocarbon contents. For the first time we observed that they contain paraffinic hydrocarbons; the average contents were 42, 58, and 146 parts per million, respectively. n-Alkanes having odd numbers of carbon atoms predom-inate, with carbon-chain lengths ranging from C(14) to C(37). The major alkanes are n-C(27) in U. maydis, n-C(27) and n-C(35) in U. nuda, and n-C(29) in S. reiliana. Each type of spore carried a distinctly characteristic population of hydrocarbons.

Phytoplankton abundance and structural parameters of the critically endangered protected area Vaya Lake (Bulgaria).

PubMed

Dimitrova, Ralits; Nenova, Elena; Uzunov, Blagoy; Shishiniova, Maria; Stoyneva, Maya

2014-09-03

Vaya (Ramsar site, protected area and Natura 2000 site) is the biggest natural lake in Bulgaria and the shallowest Black Sea coastal lake, which during the last decades has undergone significant changes and was included as critically endangered in the Red List of Bulgarian Wetlands. Our studies were conducted during the summer and autumn months of three years - 2004-2006. The paper presents results on the phytoplankton abundance (numbers, biomass and carbon content) in combination with the indices of species diversity, evenness and dominance. Phytoplankton abundance was extremely high (average values of 1135 × 10 6 cells/L for the quantity and of 46 mg/L for the biomass) and increased in the end of the studied period (years 2005-2006), when decrease of species diversity and increase of the dominance index values were detected. The carbon content of the phytoplankton was at an average value of 9.7 mg/L and also increased from 2004 to 2006. Cyanoprokaryota dominated in the formation of the total carbon content of the phytoplankton, in its numbers (88%-97.8%), and in the biomass (62%-87.9%). All data on phytoplankton abundance and structural parameters in Vaya confirm the hypertrophic status of the lake and reflect the general negative trend in its development.

Effect of home construction on soil carbon storage-A chronosequence case study.

PubMed

Majidzadeh, Hamed; Lockaby, B Graeme; Governo, Robin

2017-07-01

Urbanization results in the rapid expansion of impervious surfaces, therefore a better understanding of biogeochemical consequences of soil sealing is crucial. Previous research documents a significant reduction in soil carbon and nitrogen content, however, it is unclear if this decrease is a result of top soil removal or long-term soil sealing. In this study, soil biogeochemical properties were quantified beneath homes built on a crawl space at two depths (0-10 cm, and 10-20 cm). All homes, 11-114 years in age, were sampled in the Piedmont region of Alabama and Georgia, USA. This age range enabled the use of a chronosequence approach to estimate carbon loss or gain under the sampled homes. The difference in soil carbon content beneath homes and adjoining urban lawns showed a quadratic relation with age. Maximum C loss occurred at approximately fifty years. The same pattern was observed for MBC: C ratio suggesting that the soil carbon content was decreasing beneath the homes for first fifty years, then increased afterward. The average soil C and N content in the top 10 cm were respectively 61.86% (±4.42%), and 65.77% (±5.65%) lower underneath the homes in comparison to urban lawns. Microbial biomass carbon (MBC), and nitrogen (MBN) were significantly lower below the homes compared to the urban lawns, while bulk density and phosphorus content were higher beneath the homes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Seasonal variations in the stable carbon isotopic signature of biogenic methane in a coastal sediment

NASA Technical Reports Server (NTRS)

Martens, C. S.; Green, C. D.; Blair, N. E.; Des Marais, D. J.

1986-01-01

Systematic seasonal variations in the stable carbon isotopic signature of methane gas occur in the anoxic sediments of Cape Lookout Bight, a lagoonal basin on North Carolina's Outer Banks. Values for the carbon isotope ratio of methane range from -57.3 per mil during summer to -68.5 per mil during winter in gas bubbles with an average methane content of 95 percent. The variations are hypothesized to result from changes in the pathways of microbial methane production and cycling of key substrates including acetate and hydrogen. The use of stable isotopic signatures to investigate the global methane cycle through mass balance calculations, involving various sediment and soil biogenic sources, appears to require seasonally averaged data from individual sites.

40 CFR 98.247 - Records that must be retained.

Code of Federal Regulations, 2014 CFR

2014-07-01

....246(b), and records of any annual average HHV calculations. (b) If you comply with the mass balance... produced, if you comply with the alternative methodology in § 98.243(c)(4) for determining carbon content...

[Responses of soil microbial carbon metabolism to the leaf litter composition in Liaohe River Nature Reserve of northern Hebei Province, China].

PubMed

Li, Tian-yu; Kang, Feng-feng; Han, Hai-rong; Gao, Jing; Song, Xiao-shuai; Yu, Shu; Zhao, Jin-long; Yu, Xiao-wen

2015-03-01

Using litter bag method, we studied the effects of single and mixed litters from Betula platyphlla, Populus davidiana and Quercus mongolica on soil microbial biomass carbon (MBC), microbial respiration (MR) and microbial metabolic quotient (qCO2) in 0-5, 5-10 and 10-20 cm soil layers. The results showed that the average contents of MBC in 0-20 cm soil layer were 124.84, 325.29, 349.79 and 319.02 mg . kg-1 in the leaf litter removal treatment, Betula platyphlla treatment, Populus davidiana treatment and Quercus mongolica treatment, and the corresponding average rates of MR were 0.66, 1.12, 1.16 and 1.10 µg . g-1 . h-1, respectively. Meanwhile, in 0-20 cm soil layer, the average contents of MBC in the treatments with single leaf litter, mixed litter of two plant species and mixed litter of three plant species were 331. 37, 418. 52 and 529. 34 mg . kg-1, and the corresponding average rates of MR were 1.13, 1.30 and 1.46 µg . g-1 . h-1, respectively. In contrast to the MBC and MR, qCO2 in soil showed a reverse pattern. Our study suggested that characteristics of microbial carbolic metabolism were influenced by litter quality. Namely, the treatment with high litter quality had higher MBC, MR and utilization efficiency of soil carbon, compared with the treatment with low litter quality. Moreover, mixture of different species of leaf litter improved soil microbial activities, increased utilization efficiency on soil carbon and promoted diversity of microbial metabolic pathways, which could then contribute to maintaining and enhancing soil quality of forestland.

Windthrows increase soil carbon stocks in a central Amazon forest

NASA Astrophysics Data System (ADS)

dos Santos, Leandro T.; Magnabosco Marra, Daniel; Trumbore, Susan; de Camargo, Plínio B.; Negrón-Juárez, Robinson I.; Lima, Adriano J. N.; Ribeiro, Gabriel H. P. M.; dos Santos, Joaquim; Higuchi, Niro

2016-03-01

Windthrows change forest structure and species composition in central Amazon forests. However, the effects of widespread tree mortality associated with wind disturbances on soil properties have not yet been described in this vast region. We investigated short-term effects (7 years after disturbance) of widespread tree mortality caused by a squall line event from mid-January of 2005 on soil carbon stocks and concentrations in a central Amazon terra firme forest. The soil carbon stock (averaged over a 0-30 cm depth profile) in disturbed plots (61.4 ± 8.2 Mg ha-1, mean ±95 % confidence interval) was marginally higher (p = 0.09) than that from undisturbed plots (47.7 ± 13.6 Mg ha-1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.17 %) was significantly higher (p < 0.001) than that from undisturbed plots (1.36 ± 0.24 %). Moreover, soil carbon stocks were positively correlated with soil clay content (r2 = 0.332, r = 0.575 and p = 0.019) and with tree mortality intensity (r2 = 0.257, r = 0.506 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. The higher carbon content and potentially higher nutrient availability in soils from areas recovering from windthrows may favor forest regrowth and increase vegetation resilience.

Changes in Soil Organic Carbon and Nitrogen as a Result of Cultivation

DOE Data Explorer

Post, Wilfred M [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mann, L. K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2005-01-01

We assembed and analyzed a data base of soil organic carbon and nitrogen information from over 1100 profiles in order to explore factors related to the changes in storage of soil organic matter resulting from land conversion. The relationship between cultivated and uncultivated organic carbon and nitrogen storage in soils can be described by regression lines with uncultivated storage on the abscissa, and cultivated storage on the ordinate. The slope of the regression lines is less than 1 indicating that the amount of carbon or nitrogen lost is an increasing fraction of the intial amount stored in the soil. Average carbon loss for soils with high initial carbon is 23% for 1-meter depth. Average nitrogen loss for the same depth is 6%. In addition, for soils with very low uncultivated carbon or nitrogen storage, cultivation results in increases in storage. In soils with the same uncultivated carbon contents, profiles with higher C:N ratios lost more carbon than those with low C:N ratios, suggesting that decomposition of organic matter may, in general, be more limited by microbial ability to break carbon bonds than by nitrogen deficiency.

Organic carbon accumulation and reactivity in central Swedish lakes during the Holocene

NASA Astrophysics Data System (ADS)

Chmiel, H.; Kokic, J.; Niggemann, J.; Dittmar, T.; Sobek, S.

2012-04-01

Sedimentation and burial of particulate organic carbon (POC), received from terrestrial sources and from lake internal primary production, are responsible for the progressive accumulation and long-term storage of organic matter in lake basins. For lakes in the boreal zone of central Sweden it can be presumed, that the onset of POC accumulation occurred during the early Holocene (˜8000 BP.) after the retreat of the Scandinavian ice sheet. In this study we investigated carbon mass accumulation rates (CMARs), as well as sources and reactivity of deposited organic material, for seven lakes in central Sweden (60°N, 15°E), in order to obtain a detailed temporal resolution of carbon burial and preservation in boreal lakes. Sediment long-cores were sampled in March 2011 from the ice, and CMARs were calculated from water contents, dry bulk densities, carbon contents and radiocarbon (14C) ages of the depth profiles. To indicate the sources of the organic material and characterize its diagenetic state, we determined carbon-nitrogen ratios (C/N) as well as amounts and compositions of lignin phenols. The transitions from organic rich sediment layers to glacial till deposits were found to be in sediment depths of ˜3 m in each lake. POC contents were on average highest (25-34 wt. % C), in small lakes (≤ 0.07 km2) and lowest (10-18 wt. % C) in the larger lakes (≥ 165 km2). The CMARs over the Holocene showed significant variations and were on average lower in the early Holocene, compared to recent accumulation rates. C/N values and the composition of lignin phenols further provided indications of important changes in organic matter source and reactivity over the Holocene. In summary, our data suggest that boreal lake sediments were a significantly stronger sink for organic carbon during the last ~150 years than during earlier periods of the Holocene.

Combining Soil Databases for Topsoil Organic Carbon Mapping in Europe.

PubMed

Aksoy, Ece; Yigini, Yusuf; Montanarella, Luca

2016-01-01

Accuracy in assessing the distribution of soil organic carbon (SOC) is an important issue because of playing key roles in the functions of both natural ecosystems and agricultural systems. There are several studies in the literature with the aim of finding the best method to assess and map the distribution of SOC content for Europe. Therefore this study aims searching for another aspect of this issue by looking to the performances of using aggregated soil samples coming from different studies and land-uses. The total number of the soil samples in this study was 23,835 and they're collected from the "Land Use/Cover Area frame Statistical Survey" (LUCAS) Project (samples from agricultural soil), BioSoil Project (samples from forest soil), and "Soil Transformations in European Catchments" (SoilTrEC) Project (samples from local soil data coming from six different critical zone observatories (CZOs) in Europe). Moreover, 15 spatial indicators (slope, aspect, elevation, compound topographic index (CTI), CORINE land-cover classification, parent material, texture, world reference base (WRB) soil classification, geological formations, annual average temperature, min-max temperature, total precipitation and average precipitation (for years 1960-1990 and 2000-2010)) were used as auxiliary variables in this prediction. One of the most popular geostatistical techniques, Regression-Kriging (RK), was applied to build the model and assess the distribution of SOC. This study showed that, even though RK method was appropriate for successful SOC mapping, using combined databases was not helpful to increase the statistical significance of the method results for assessing the SOC distribution. According to our results; SOC variation was mainly affected by elevation, slope, CTI, average temperature, average and total precipitation, texture, WRB and CORINE variables for Europe scale in our model. Moreover, the highest average SOC contents were found in the wetland areas; agricultural areas have much lower soil organic carbon content than forest and semi natural areas; Ireland, Sweden and Finland has the highest SOC, on the contrary, Portugal, Poland, Hungary, Spain, Italy have the lowest values with the average 3%.

Combining Soil Databases for Topsoil Organic Carbon Mapping in Europe

PubMed Central

Aksoy, Ece

2016-01-01

Accuracy in assessing the distribution of soil organic carbon (SOC) is an important issue because of playing key roles in the functions of both natural ecosystems and agricultural systems. There are several studies in the literature with the aim of finding the best method to assess and map the distribution of SOC content for Europe. Therefore this study aims searching for another aspect of this issue by looking to the performances of using aggregated soil samples coming from different studies and land-uses. The total number of the soil samples in this study was 23,835 and they’re collected from the “Land Use/Cover Area frame Statistical Survey” (LUCAS) Project (samples from agricultural soil), BioSoil Project (samples from forest soil), and “Soil Transformations in European Catchments” (SoilTrEC) Project (samples from local soil data coming from six different critical zone observatories (CZOs) in Europe). Moreover, 15 spatial indicators (slope, aspect, elevation, compound topographic index (CTI), CORINE land-cover classification, parent material, texture, world reference base (WRB) soil classification, geological formations, annual average temperature, min-max temperature, total precipitation and average precipitation (for years 1960–1990 and 2000–2010)) were used as auxiliary variables in this prediction. One of the most popular geostatistical techniques, Regression-Kriging (RK), was applied to build the model and assess the distribution of SOC. This study showed that, even though RK method was appropriate for successful SOC mapping, using combined databases was not helpful to increase the statistical significance of the method results for assessing the SOC distribution. According to our results; SOC variation was mainly affected by elevation, slope, CTI, average temperature, average and total precipitation, texture, WRB and CORINE variables for Europe scale in our model. Moreover, the highest average SOC contents were found in the wetland areas; agricultural areas have much lower soil organic carbon content than forest and semi natural areas; Ireland, Sweden and Finland has the highest SOC, on the contrary, Portugal, Poland, Hungary, Spain, Italy have the lowest values with the average 3%. PMID:27011357

Sediment Carbon Accumulation in Southern Latitude Saltmarsh Communities of Tasmania, Australia.

PubMed

Ellison, Joanna C; Beasy, Kim M

2018-05-02

Carbon sequestration values of wetlands are greatest in their sediments. Northern hemisphere research dominates the earlier saltmarsh carbon sequestration literature, recently augmented by analyses across mainland Australia where species assemblages, catchment histories and environmental settings differ. No previous assessment has been made for Tasmania. Carbon stores and accumulation rates in saltmarsh sediments of the Rubicon estuary, Tasmania, were investigated. Carbon was determined from sediment cores by Elemental Analyser, combined with analysis of organic content and bulk density. Carbon accumulation was determined using short-term and long-term sediment accretion indicators. Results showed carbon densities to be lower than global averages, with variation found between carbon stores of native and introduced species zones. Cores from introduced Spartina anglica indicated a trend of higher sediment carbon percentages relative to cores from native saltmarsh Juncus kraussii and Sarcocornia quinqueflora , and in finer grain sizes. Sediment carbon stock of 30 cm depths was 49.5 Mg C ha −1 for native saltmarsh and 55.5 Mg C ha −1 for Spartina . Carbon percentages were low owing to high catchment inorganic sediment yields, however carbon accumulation rates were similar to global averages, particularly under Spartina . Covering 85% of saltmarsh area in the estuary, Spartina contributes the majority to carbon stores, potentially indicating a previously unrecognized value for this invasive species in Australia.

Carbon sequestration via reaction with basaltic rocks: geochemical modeling and experimental results

USGS Publications Warehouse

Rosenbauer, Robert J.; Thomas, Burt; Bischoff, James L.; Palandri, James

2012-01-01

Basaltic rocks are potential repositories for sequestering carbon dioxide (CO2) because of their capacity for trapping CO2 in carbonate minerals. We carried out a series of thermodynamic equilibrium models and high pressure experiments, reacting basalt with CO2-charged fluids over a range of conditions from 50 to 200 °C at 300 bar. Results indicate basalt has a high reactivity to CO2 acidified brine. Carbon dioxide is taken up from solution at all temperatures from 50 to 200 °C, 300 bar, but the maximum extent and rate of reaction occurs at 100 °C, 300 bar. Reaction path simulations utilizing the geochemical modeling program CHILLER predicted an equilibrium carbonate alteration assemblage of calcite, magnesite, and siderite, but the only secondary carbonate identified in the experiments was a ferroan magnesite. The amount of uptake at 100 °C, 300 bar ranged from 8% by weight for a typical tholeite to 26% for a picrite. The actual amount of CO2 uptake and extent of rock alteration coincides directly with the magnesium content of the rock suggesting that overall reaction extent is controlled by bulk basalt Mg content. In terms of sequestering CO2, an average basaltic MgO content of 8% is equivalent to 2.6 × 108 metric ton CO2/km3 basalt.

Soil respiration characteristics in different land uses and response of soil organic carbon to biochar addition in high-latitude agricultural area.

PubMed

Ouyang, Wei; Geng, Xiaojun; Huang, Wejia; Hao, Fanghua; Zhao, Jinbo

2016-02-01

The farmland tillage practices changed the soil chemical properties, which also impacted the soil respiration (R s ) process and the soil carbon conservation. Originally, the farmland in northeast China had high soil carbon content, which was decreased in the recent decades due to the tillage practices. To better understand the R s dynamics in different land use types and its relationship with soil carbon loss, soil samples at two layers (0-15 and 15-30 cm) were analyzed for organic carbon (OC), total nitrogen (TN), total phosphorus (TP), total carbon (TC), available nitrogen (AN), available phosphorus (AP), soil particle size distribution, as well as the R s rate. The R s rate of the paddy land was 0.22 (at 0-15 cm) and 3.01 (at 15-30 cm) times of the upland. The average concentrations of OC and clay content in cultivated areas were much lower than in non-cultivated areas. The partial least squares analysis suggested that the TC and TN were significantly related to the R s process in cultivated soils. The upland soil was further used to test soil CO2 emission response at different biochar addition levels during 70-days incubation. The measurement in the limited incubation period demonstrated that the addition of biochar improved the soil C content because it had high concentration of pyrogenic C, which was resistant to mineralization. The analysis showed that biochar addition can promote soil OC by mitigating carbon dioxide (CO2) emission. The biochar addition achieved the best performance for the soil carbon conservation in high-latitude agricultural area due to the originally high carbon content.

Windthrows increase soil carbon stocks in a central Amazon forest

DOE PAGES

dos Santos, Leandro T.; Magnabosco Marra, Daniel; Trumbore, Susan; ...

2016-03-02

Windthrows change forest structure and species composition in central Amazon forests. However, the effects of widespread tree mortality associated with wind disturbances on soil properties have not yet been described in this vast region. We investigated short-term effects (7 years after disturbance) of widespread tree mortality caused by a squall line event from mid-January of 2005 on soil carbon stocks and concentrations in a central Amazon terra firme forest. The soil carbon stock (averaged over a 0–30 cm depth profile) in disturbed plots (61.4 ± 8.2 Mg ha -1, mean ±95 % confidence interval) was marginally higher ( p =more » 0.09) than that from undisturbed plots (47.7 ± 13.6 Mg ha -1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.17 %) was significantly higher ( p < 0.001) than that from undisturbed plots (1.36 ± 0.24 %). Moreover, soil carbon stocks were positively correlated with soil clay content ( r 2 = 0.332, r = 0.575 and p = 0.019) and with tree mortality intensity ( r 2 = 0.257, r = 0.506 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. The higher carbon content and potentially higher nutrient availability in soils from areas recovering from windthrows may favor forest regrowth and increase vegetation resilience.« less

Windthrows increase soil carbon stocks in a central Amazon forest

DOE Office of Scientific and Technical Information (OSTI.GOV)

dos Santos, Leandro T.; Magnabosco Marra, Daniel; Trumbore, Susan

Windthrows change forest structure and species composition in central Amazon forests. However, the effects of widespread tree mortality associated with wind disturbances on soil properties have not yet been described in this vast region. We investigated short-term effects (7 years after disturbance) of widespread tree mortality caused by a squall line event from mid-January of 2005 on soil carbon stocks and concentrations in a central Amazon terra firme forest. The soil carbon stock (averaged over a 0–30 cm depth profile) in disturbed plots (61.4 ± 8.2 Mg ha -1, mean ±95 % confidence interval) was marginally higher ( p =more » 0.09) than that from undisturbed plots (47.7 ± 13.6 Mg ha -1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.17 %) was significantly higher ( p < 0.001) than that from undisturbed plots (1.36 ± 0.24 %). Moreover, soil carbon stocks were positively correlated with soil clay content ( r 2 = 0.332, r = 0.575 and p = 0.019) and with tree mortality intensity ( r 2 = 0.257, r = 0.506 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. The higher carbon content and potentially higher nutrient availability in soils from areas recovering from windthrows may favor forest regrowth and increase vegetation resilience.« less

Cross-sectional survey of the amount of free sugars and calories in carbonated sugar-sweetened beverages on sale in the UK

PubMed Central

Hashem, Kawther M; He, Feng J; Jenner, Katharine H; MacGregor, Graham A

2016-01-01

Objectives To investigate the free sugars and calorie content of carbonated sugar-sweetened beverages (CSSB) available in the main UK supermarkets. Study design We carried out a cross-sectional survey in 2014 of 169 CSSB. Methods The free sugars (sugars g/100 mL) and calorie (kcal/100 mL) were collected from product packaging and nutrient information panels of CSSB available in 9 main UK supermarkets. Results The average free sugars content in CSSB was 30.1±10.7 g/330 mL, and 91% of CSSB would receive a ‘red’ (high) label for sugars per serving. There was a large variation in sugars content between different flavours of CSSB and within the same type of flavour ranging from 3.3 to 52.8 g/330 mL. On average, ginger beer (38.5±9.9 g/330 mL) contained the highest amounts of sugars and ginger ale (22.9±7.7 g/330 mL) contained the lowest. Cola flavour is the most popular flavour in the UK with an average free sugars content of 35.0±1.1 g/330 mL. On average, the supermarket own brand contained lower levels of sugars than branded products (27.9±10.6 vs 31.6±10.6 g/330 mL, p=0.02). The average calorie content in CSSB was 126.1±43.5 kcal/330 mL. Cola flavour had a calorie content of 143.5±5.2 kcal/330 mL. Among the 169 products surveyed, 55% exceeded the maximum daily recommendation for free sugars intake (30 g) per 330 mL. Conclusions Free sugars content of CSSB in the UK is high and is a major contributor to free sugars intake. There is a wide variation in the sugars content of CSSB and even within the same flavour of CSSB. These findings demonstrate that the amount of free sugars added to CSSB can be reduced without technical issues, and there is an urgent need to set incremental free sugars reduction targets. A reduction in sugars content and overall CSSB consumption will be very beneficial in reducing obesity, type 2 diabetes and dental caries. PMID:28186923

Cross-sectional survey of the amount of free sugars and calories in carbonated sugar-sweetened beverages on sale in the UK.

PubMed

Hashem, Kawther M; He, Feng J; Jenner, Katharine H; MacGregor, Graham A

2016-11-15

To investigate the free sugars and calorie content of carbonated sugar-sweetened beverages (CSSB) available in the main UK supermarkets. We carried out a cross-sectional survey in 2014 of 169 CSSB. The free sugars (sugars g/100 mL) and calorie (kcal/100 mL) were collected from product packaging and nutrient information panels of CSSB available in 9 main UK supermarkets. The average free sugars content in CSSB was 30.1±10.7 g/330 mL, and 91% of CSSB would receive a 'red' (high) label for sugars per serving. There was a large variation in sugars content between different flavours of CSSB and within the same type of flavour ranging from 3.3 to 52.8 g/330 mL. On average, ginger beer (38.5±9.9 g/330 mL) contained the highest amounts of sugars and ginger ale (22.9±7.7 g/330 mL) contained the lowest. Cola flavour is the most popular flavour in the UK with an average free sugars content of 35.0±1.1 g/330 mL. On average, the supermarket own brand contained lower levels of sugars than branded products (27.9±10.6 vs 31.6±10.6 g/330 mL, p=0.02). The average calorie content in CSSB was 126.1±43.5 kcal/330 mL. Cola flavour had a calorie content of 143.5±5.2 kcal/330 mL. Among the 169 products surveyed, 55% exceeded the maximum daily recommendation for free sugars intake (30 g) per 330 mL. Free sugars content of CSSB in the UK is high and is a major contributor to free sugars intake. There is a wide variation in the sugars content of CSSB and even within the same flavour of CSSB. These findings demonstrate that the amount of free sugars added to CSSB can be reduced without technical issues, and there is an urgent need to set incremental free sugars reduction targets. A reduction in sugars content and overall CSSB consumption will be very beneficial in reducing obesity, type 2 diabetes and dental caries. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Laboratory Experiments to Evaluate Matrix Diffusion of Dissolved Organic Carbon Carbon-14 in Southern Nevada Fractured-rock Aquifers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hershey, Ronald L.; Fereday, Wyatt

Dissolved inorganic carbon (DIC) carbon-14 ( 14C) is used to estimate groundwater ages by comparing the DIC 14C content in groundwater in the recharge area to the DIC 14C content in the downgradient sampling point. However, because of chemical reactions and physical processes between groundwater and aquifer rocks, the amount of DIC 14C in groundwater can change and result in 14C loss that is not because of radioactive decay. This loss of DIC 14C results in groundwater ages that are older than the actual groundwater ages. Alternatively, dissolved organic carbon (DOC) 14C in groundwater does not react chemically with aquifermore » rocks, so DOC 14C ages are generally younger than DIC 14C ages. In addition to chemical reactions, 14C ages may also be altered by the physical process of matrix diffusion. The net effect of a continuous loss of 14C to the aquifer matrix by matrix diffusion and then radioactive decay is that groundwater appears to be older than it actually is. Laboratory experiments were conducted to measure matrix diffusion coefficients for DOC 14C in volcanic and carbonate aquifer rocks from southern Nevada. Experiments were conducted using bromide (Br-) as a conservative tracer and 14C-labeled trimesic acid (TMA) as a surrogate for groundwater DOC. Outcrop samples from six volcanic aquifers and five carbonate aquifers in southern Nevada were used. The average DOC 14C matrix diffusion coefficient for volcanic rocks was 2.9 x 10 -7 cm 2/s, whereas the average for carbonate rocks was approximately the same at 1.7 x 10 -7 cm 2/s. The average Br- matrix diffusion coefficient for volcanic rocks was 10.4 x 10 -7 cm 2/s, whereas the average for carbonate rocks was less at 6.5 x 10 -7 cm 2/s. Carbonate rocks exhibited greater variability in DOC 14C and Br- matrix diffusion coefficients than volcanic rocks. These results confirmed, at the laboratory scale, that the diffusion of DOC 14C into southern Nevada volcanic and carbonate aquifers is slower than DIC 14C. Because of the apparent sorption of 14C-labeled TMA in the experiments, matrix diffusion coefficients are likely even lower. The reasons for the higher than expected Br-/ 14C-labeled TMA are unknown. Because the molecular size of TMA is on the low end of the range in molecular size for typical humic substances, the matrix diffusion coefficients for the 14C-labeled TMA likely represent close to the maximum diffusion rates for DOC 14C in the volcanic and carbonate aquifers in southern Nevada.« less

Waterlogging accelerates the loss of soil organic carbon from abandoned paddy fields in the hilly terrain in subtropical China.

PubMed

Xie, Xiao Li; Wang, Wei; Tian, Wen Wen; Xie, Ke Jun

2017-11-06

Paddy soils have been widely recognized as important carbon sinks. However, paddy field abandonment is increasing in the hilly area in subtropical China. Soil waterlogging and weed burning are common practices in abandoned paddy fields, which could affect vegetation cover and carbon sequestration. An rice cultivation experiment was ceased in 2006, and four new treatments were applied as waterlogging (W), drainage (D), waterlogging combined with burning (WB), and drainage combined with burning (DB). Waterlogging altered the vegetation cover and caused an associated change in biomass. Paspalum paspaloides, Murdannia triquetra, and Bidens frondosa dominated W and WB plots, and Microstegium vimineum and Bidens frondosa dominated D and DB plots. Abandonment of paddy fields led to a rapid decrease in soil organic carbon (SOC), and waterlogging accelerates SOC loss which should be attributed mainly to alteration of the vegetation cover. Six years' rice cultivation increased SOC content by 13.5% (2.4 g kg -1 ) on average. In contrast, six years' abandonment reduced SOC content by 14.5% (3.0 g kg -1 ) on average. Decline rate of SOC was 0.38, 0.64, 0.30, and 0.65 g kg -1 a -1 for D, W, DB, and WB, respectively. Such results indicate a significant risk of SOC loss from abandoned paddy fields.

Historical record of black carbon in urban soils and its environmental implications.

PubMed

He, Yue; Zhang, Gan-Lin

2009-10-01

Energy use in urbanization has fundamentally changed the pattern and fluxes of carbon cycling, which has global and local environmental impacts. Here we have investigated organic carbon (OC) and black carbon (BC) in six soil profiles from two contrast zones in an ancient city (Nanjing) in China. BC in soils was widely variable, from 0.22 to 32.19 g kg(-1). Its average concentration in an ancient residential area (Zone 1) was, 0.91 g kg(-1), whereas in Zone 2, an industrial and commercial area, the figure was 8.62 g kg(-1). The ratio of BC/OC ranged from 0.06 to 1.29 in soil profiles, with an average of 0.29. The vertical distribution of BC in soil is suggested to reflect the history of BC formation from burning of biomass and/or fossil fuel. BC in the surface layer of soils was mainly from traffic emission (especially from diesel vehicles). In contrast, in cultural layers BC was formed from historical coal use. The contents of BC and the ratio of BC/OC may reflect different human activities and pollution sources in the contrasting urban zones. In addition, the significant correlation of heavy metals (Cu, Pb, and Zn) with BC contents in some culture layers suggests the sorption of the metals by BC or their coexistence resulted from the coal-involved smelting.

Surface morphology and grain analysis of successively industrially grown amorphous hydrogenated carbon films (a-C:H) on silicon

NASA Astrophysics Data System (ADS)

Catena, Alberto; McJunkin, Thomas; Agnello, Simonpietro; Gelardi, Franco M.; Wehner, Stefan; Fischer, Christian B.

2015-08-01

Silicon (1 0 0) has been gradually covered by amorphous hydrogenated carbon (a-C:H) films via an industrial process. Two types of these diamond-like carbon (DLC) coatings, one more flexible (f-DLC) and one more robust (r-DLC), have been investigated. Both types have been grown by a radio frequency plasma-enhanced chemical vapor deposition (RF-PECVD) technique with acetylene plasma. Surface morphologies have been studied in detail by atomic force microscopy (AFM) and Raman spectroscopy has been used to investigate the DLC structure. Both types appeared to have very similar morphology and sp2 carbon arrangement. The average height and area for single grains have been analyzed for all depositions. A random distribution of grain heights was found for both types. The individual grain structures between the f- and r-type revealed differences: the shape for the f-DLC grains is steeper than for the r-DLC grains. By correlating the average grain heights to the average grain areas for all depositions a limited region is identified, suggesting a certain regularity during the DLC deposition mechanisms that confines both values. A growth of the sp2 carbon entities for high r-DLC depositions is revealed and connected to a structural rearrangement of carbon atom hybridizations and hydrogen content in the DLC structure.

Windthrows increase soil carbon stocks in a Central Amazon forest

NASA Astrophysics Data System (ADS)

dos Santos, L. T.; Magnabosco Marra, D.; Trumbore, S.; Camargo, P. B.; Chambers, J. Q.; Negrón-Juárez, R. I.; Lima, A. J. N.; Ribeiro, G. H. P. M.; dos Santos, J.; Higuchi, N.

2015-12-01

Windthrows change forest structure and species composition in Central Amazon forests. However, the effects of widespread tree mortality associated with wind-disturbances on soil properties have not yet been described. In this study, we investigated short-term effects (seven years after disturbance) of a windthrow event on soil carbon stocks and concentrations in a Central Amazon terra firme forest. The soil carbon stock (averaged over a 0-30 cm depth profile) in disturbed plots (61.4 ± 4.18 Mg ha-1, mean ± standard error) was marginally higher (p = 0.009) than that from undisturbed plots (47.7 ± 6.95 Mg ha-1). The soil organic carbon concentration in disturbed plots (2.0 ± 0.08 %) was significantly higher (p < 0.001) than that from undisturbed plots (1.36 ± 0.12 %). Moreover, soil carbon stocks were positively correlated with soil clay content (r = 0.575 and p = 0.019) and with tree mortality intensity (r = 0.493 and p = 0.045). Our results indicate that large inputs of plant litter associated with large windthrow events cause a short-term increase in soil carbon content, and the degree of increase is related to soil clay content and tree mortality intensity. Higher nutrient availability in soils from large canopy gaps created by wind disturbance may increase vegetation resilience and favor forest recovery.

[Estimation of vegetation carbon storage and density of forests at tree layer in Tibet, China.

PubMed

Liu, Shu Qin; Xia, Chao Zong; Feng, Wei; Zhang, Ke Bin; Ma, Li; Liu, Jian Kang

2017-10-01

The estimation of vegetation carbon storage and density of forests at tree layer in Tibet Autonomous Region was calculated based on the eighth forest inventory data using the biomass inventory method, as well as other attributes like tree trunk density and carbon content of different species. The results showed that the total carbon storage at tree layer in Tibet forest ecosystem was 1.067×10 9 t and the average carbon density was 72.49 t·hm -2 . The carbon storage at tree layer of different stands was in the order of arbor forest > scattered wood > sparse forest > alluvial tree. The carbon storage of different forest types at tree layer were in the order of shelterbelt > special purpose forest > timber forest > firewood forest. The proportion of the first mentioned two was 88.5%, and the average carbon density of different forest types at tree layer was 88.09 t·hm -2 . The carbon sto-rage and its distribution area at tree layer in different forest groups were in the same order, followed by mature forest > over mature forest > near mature forest > middle aged forest > young forest. The carbon storage in mature forests accounted for 50% of the total carbon storage at tree layer in diffe-rent forest groups. The carbon storage at tree layer in different forest groups increased first and then decreased with the increase of stand ages.

Kinetic Modeling of the Reaction Rate for Quartz and Carbon Black Pellet

NASA Astrophysics Data System (ADS)

Li, Fei; Tangstad, Merete

2018-06-01

The kinetic modeling for the carbothermal reduction reaction rate in quartz and carbon black pellets is studied at different temperatures, under varying CO partial pressures in ambient atmosphere, varying carbon contents, different quartz particle sizes, and different crucible opening areas. Carbon black is produced by the cracking of natural gas. The activation energy of the SiC-producing step was determined to be 594 kJ/mol. The averaged pre-exponential factor A obtained from 1898 K, 1923 K, and 1948 K (1625 °C, 1650 °C, and 1675 °C) is 2.62E+16 min-1. The reaction rate of the gas-solid interface factor, fix-C content ( X fix-C), temperature ( T), and CO partial pressure ( X CO) can be expressed as follows: {{d/pct}}{{{d}t}} = (1 - 0.40 × X_{{{fix} - C}}^{ - 0.86} × {pct}) × 2.62 × 10^{16} × \\exp ( { - 594000/RT} ) × (2.6 - 0.015 × X_{co} ).

[Spatial variation of soil carbon and stable isotopes in the southern margin desert of Junggar Basin, China].

PubMed

Wang, Na; Xu, Wen Qiang; Xu, Hua Jun; Feng, Yi Xing; Li, Chao Fan

2017-07-18

The southern margin desert of Junggar Basin in the central arid region of Asia was selec-ted as the study area. To gain insight into the distribution characteristic of stable carbon isotope and the relationship between the change of soil carbon and the distance to oasis of soil organic carbon (SOC) and soil inorganic carbon (SIC), three belt transects were set according to the distance between the desert and the oasis in edge, middle and hinterland of the desert respectively, and collected the soil profile samples with depth of 2 m. The results indicated that the SOC content reduced with the soil depth, and the variation with the distance to oasis was the edge> the middle> the hinterland. The δ 13 C value of SOC varied in the range of -21.92‰ to -17.41‰, and decreased with the depth; the range in the middle and hinterland was -25.20‰ to -19.30‰, and increased then declined with the depth. Therefore, we could infer that the C3 plants played a dominant role in the central of desert, and had experienced the succession from C3 plants to C4 plants. The average content of SIC was 38.98 g·kg -1 in the edge of desert, which was about 6.01 folds as large as the content in the hinterland. This indicated that a large number of SIC with 0-2 m depth were clustered in the edge of the desert. The δ 13 C value of SIC increased first then decreased with the soil depth, and enriched in the bottom layer, which was mainly affected by the original carbonate content and soil carbon dioxide.

Human population and atmospheric carbon dioxide growth dynamics: Diagnostics for the future

NASA Astrophysics Data System (ADS)

Hüsler, A. D.; Sornette, D.

2014-10-01

We analyze the growth rates of human population and of atmospheric carbon dioxide by comparing the relative merits of two benchmark models, the exponential law and the finite-time-singular (FTS) power law. The later results from positive feedbacks, either direct or mediated by other dynamical variables, as shown in our presentation of a simple endogenous macroeconomic dynamical growth model describing the growth dynamics of coupled processes involving human population (labor in economic terms), capital and technology (proxies by CO2 emissions). Human population in the context of our energy intensive economies constitutes arguably the most important underlying driving variable of the content of carbon dioxide in the atmosphere. Using some of the best databases available, we perform empirical analyses confirming that the human population on Earth has been growing super-exponentially until the mid-1960s, followed by a decelerated sub-exponential growth, with a tendency to plateau at just an exponential growth in the last decade with an average growth rate of 1.0% per year. In contrast, we find that the content of carbon dioxide in the atmosphere has continued to accelerate super-exponentially until 1990, with a transition to a progressive deceleration since then, with an average growth rate of approximately 2% per year in the last decade. To go back to CO2 atmosphere contents equal to or smaller than the level of 1990 as has been the broadly advertised goals of international treaties since 1990 requires herculean changes: from a dynamical point of view, the approximately exponential growth must not only turn to negative acceleration but also negative velocity to reverse the trend.

Physicochemical properties and carbon density of alpine sod layer with their variation across habitat gradients in the Zoige Plateau

NASA Astrophysics Data System (ADS)

Peixi, Su; Zijuan, Zhou; Rui, Shi; tingting, Xie

2017-04-01

The alpine sod layer is a soft, tough and resistant to shifting surface soil layer under the formation of the natural vegetation in the plateau cold region, understanding its ecological function is a prerequisite to promote grass and animal husbandry production for recuperation and protection, and the active use of project construction. Based on the extensive investigation on the alpine vegetation of the Zoige Plateau in the Eastern Qinghai-Tibetan Plateau of China, set up moisture gradient community sample plots: swamp, degraded swamp, swampy meadow, wet meadow, dry meadow and degraded meadow, and the elevation gradient community sample plots: subalpine meadow, subalpine shrub meadow, alpine shrub meadow and alpine meadow were set up. The sod layer bulk density, soil particle composition and soil organic carbon (SOC) content of different types of community plots were analyzed and to compare its carbon sequestration capacity on the moisture and elevation gradients. The results showed that the average thickness of the sod layer was 30 cm, the bulk density of the swamp was the smallest, and the SOC content was above 300 g/kg. The bulk density of degraded meadow was the highest while its SOC content was decreased significantly. The SOC density of sod layer in different communities was between 10 and 24 kg C/m2, and decreased with the decreasing of soil water availability, and meadow degradation significantly decreased the soil organic carbon storage in sod layer. The sod layer SOC density of alpine shrub meadow was 15% higher than that of meadow on the altitudinal gradient. It was concluded that the mass water content threshold value for maintaining the sod layer stable is 30%. In the degraded succession of alpine vegetation from swamp to meadow, the bulk density and compactness of sod layer became larger, while the organic carbon content, carbon density and carbon storage decreased. The higher the gravel content of swamp, the more easily degraded, and the higher the sand content of the meadow, the more easily degraded. Shrub meadow had higher carbon sequestration capacity than that of meadow, but the productive function of shrub meadow was lower. Keeping the sustainable development of grassland productivity and maintaining the carbon sequestration ecological function, it is necessary to prevent the degradation of the sod layer, and restrain the succession from meadow to scrub meadow. Key Words: surface soil layer, soil organic carbon, carbon density, alpine vegetation, Zoige Plateau

Stable Carbon Isotope Enrichment Before Late Miocene and Its Iimplication for Landscape Change in the Amazon Basin

NASA Astrophysics Data System (ADS)

Lee, Y. I.; Kim, D.; Hyeong, K.; Chan Min, Y.

2016-12-01

The appearance and development of C4 plants in the Late Miocene is well-established by various lines of evidence including stable carbon isotope data, yet the stable carbon isotope change before the global vegetation change has not been reported. Prior to the C4 plant expansion, the ecosystem may have been composed of C3 plants. Here we present the content and stable carbon isotope record of black carbon (BC) in a 470-cm-long piston core retrieved from the northeastern equatorial Pacific. Although suitable age dating method is lacking for the studied core, correlation of clay mineral composition, BC content, and stable carbon isotope data with a nearby well-studied core (Kim et al., submitted) at the same latitude suggests that the studied core contains sediment older than 15 Ma (330 cm in depth) and possibly back to 25 Ma, much prior to the major diversification of C4 plants. The older sediment was derived from Southern Hemisphere. The δ13C value of BC in the oldest sediment shows a relatively high value ( -22.7 ‰ on average), similar to that of C4 expansion event, and then decreases with time till reaching normal δ13C value of C3-dominated environment (-25.3 ‰ on average) around 13 Ma. This relatively high δ13C value reflects the presence of specific ecosystem, likely Pebas wetland that dominated western Amazonia before 17 Ma, and decreasing δ13C value suggests subsequent gradual development of closed-forest ecosystem. The BC content shows an abrupt increase around 400 cm, suggesting a significant aridity event in South America. Uplift of the North Andean region at 23 Ma seems to be the likely cause of such aridity event. From these observations, we argue that by comparing with the well-studied core data environmental record provided by BC data can be used for approximate age dating of deep-sea core sediment lacking appropriate dating tools, and that carbon isotope data before C4 development event may also provide information about specific regional ecosystem

Carbon stocks in mangroves, salt marshes, and salt barrens in Tampa Bay, Florida, USA: Vegetative and soil characteristics.

NASA Astrophysics Data System (ADS)

Moyer, R. P.; Radabaugh, K.; Chappel, A. R.; Powell, C.; Bociu, I.; Smoak, J. M.

2017-12-01

When compared to other terrestrial environments, coastal "blue carbon" habitats such as salt marshes and mangrove forests sequester disproportionately large amounts of carbon as standing plant biomass and sedimentary peat deposits. This study quantified total carbon stocks in vegetation and soil of 17 salt marshes, salt barrens, and mangrove forests in Tampa Bay, Florida, USA. The sites included natural, restored, and created wetlands of varying ages and degrees of anthropogenic impacts. The average vegetative carbon stock in mangrove forests was 60.1 ± 2.7 Mg ha-1. Mangrove forests frequently consisted of a few large Avicennia germinans trees with smaller, abundant Rhizophora mangle and/or Laguncularia racemosa trees. The average vegetative carbon stock was 11.8 ± 3.7 Mg ha-1 for salt marshes and 2.0 ± 1.2 Mg ha-1 for salt barrens. Vegetative carbon did not significantly differ between natural and newly created salt marsh habitats, indicating that mature restored wetlands can be included with natural wetlands for the calculation of vegetative carbon in coastal blue carbon assessments. Peat deposits were generally less than 50 cm thick and organic content rapidly decreased with depth in all habitats. Soil in this study was analyzed in 1 cm intervals; the accuracy of subsampling or binning soil into depth intervals of 2-5 cm was also assessed. In most cases, carbon stock values obtained from these larger sampling intervals were not statistically different from values obtained from sampling at 1 cm intervals. In the first 15 cm, soil in mangrove forests contained an average of 15.1% organic carbon by weight, salt marshes contained 6.5%, and salt barrens contained 0.8%. Total carbon stock in mangroves was 187.1±17.3 Mg ha-1, with 68% of that carbon stored in soil. Salt marshes contained an average of 65.2±25.3 Mg ha-1 (82% soil carbon) and salt barrens had carbon stocks of 21.4±7.4 Mg ha-1 (89% soil carbon). These values were much lower than global averages for carbon stocks in mangroves and salt marshes, likely due to Tampa Bay's location near the northern limit of mangrove habitat, recent habitat conversion from salt marshes to mangroves, young age of the restored wetlands, and proximity to intense coastal development. Vulnerability of these blue carbon habitats to climate change and sea-level rise will also be discussed.

Growth and Hydrologic Influence of European Larch and Red Pine 10 Years After Planting

Treesearch

Alfred Ray Harris; Richard S. Sartz

1972-01-01

Ten years after planting, European larch and red pine diameters averaged 11.2 and 9.6 cm, and heights averaged 9.7 and 5.1 m. Litter on the larch plots was twice as heavy as on the pine and unplanted conrtol plots. Organic carbon content of the top 5 cm of soil appeared to reflect vegetation differences, but soil bulk density did not. The amount of water depleted by...

Corrosion mechanism of carbon brick in the blast furnace hearth by potassium

NASA Astrophysics Data System (ADS)

Jiao, Ke-xin; Zhang, Jian-liang; Liu, Zheng-jian; Liu, Zhuang-zhuang; Deng, Yong; Fan, Xiaoyue

2017-11-01

Alkali plays a significant role in the formation of brittle layer of carbon brick in the blast furnace hearth. The brittle layer in a commercial blast furnace hearth was investigated. Large amounts of potassium compounds were found in the brittle layer. Subsequently, the carbon bricks which reacted with potassium in the simulation of blast furnace hearth under different contents of potassium in the brick (0.25, 0.5, 1.0 and 2.0 wt.%) during various reaction times (0.5, 1, 2 and 4 h) were experimentally studied. Finally, the formation mechanism of the brittle layer in carbon brick was clarified. The investigation results show that a large number of cracks are present in the brittle layer. The average potassium content in the brittle layer is 1 wt.%. According to the experimental results, cracks in the carbon brick can be formed by the attack of potassium. The reason for the formation of the brittle layer in the carbon brick is that the liquid potassium permeates into the carbon brick through the pores and cracks, and then reacts with SiO2 and Al2O3 in CO atmosphere. The generated potassium compounds nepheline and leucite lead to the volume expansion and the damage of the carbon brick.

[Seasonality and contribution to acid rain of the carbon abundance in rainwater].

PubMed

Xu, Tao; Song, Zhi-guang; Liu, Jun-feng; Wang, Cui-ping

2008-02-01

This paper reports the results from a study of the carbon abundance in rainwater of Guangzhou city, China. The determination of TOC, DOC, POC and PEC helps to study the seasonality of carbon abundance and its contribution to the acid rain. The results display the fact that the average contents of TOC, DOC, POC and PEC are 7.10 mg/L, 3.58 mg/L, 3.60 mg/L and 0.72 mg/L, respectively. These results confirm the deep effect of the organic pollutant to the rain. The seasonality exists in the carbon abundance of rainwater. The contents of TOC and DOC are up to the maximum in spring and the minimum in summer; the contribution of POC to TOC in summer is obviously higher than that in other seasons; and the relative content of POC is clearly higher in dry season than that in wet season. The seasonality reflects the more emission of the total pollutant in spring and the solid particle pollutant in summer than those in other seasons. Moreover, the emission of the organic pollutant from the mobile vehicles is more obvious in dry season than that in wet season. The contents of TOC and DOC have the negative correlation to the pH values, which confirms the contribution effect of the organic pollutant, such as vehicle emission, to the acid rain.

Spatially simulating changes of soil water content and their effects on carbon sequestration in Canada's forests and wetlands

NASA Astrophysics Data System (ADS)

Ju, Weimin; Chen, Jing M.; Black, T. Andrew; Barr, Alan G.; McCaughey, Harry

2010-07-01

The variations of soil water content (SWC) and its influences on the carbon (C) cycle in Canada's forests and wetlands were studied through model simulations using the Integrated Terrestrial Ecosystem Carbon (InTEC) model. It shows that Canada's forests and wetlands experienced spatially and temporally heterogeneous changes in SWC from 1901 to 2000. SWC changes caused average NPP to decrease 40.8 Tg C yr-1 from 1901 to 2000, whereas the integrated effect of non-disturbance factors (climate change, CO2 fertilization and N deposition) enhanced NPP by 9.9%. During 1981-2000, the reduction of NPP caused by changes in SWC was 58.1 Tg C yr-1 whereas non-disturbance factors together caused NPP to increase by 16.6%. SWC changes resulted in an average increase of 4.1 Tg C yr-1 in the net C uptake during 1901-2000, relatively small compared with the enhancement in C uptake of 50.2 Tg C yr-1 by the integrated effect of non-disturbance factors. During 1981-2000, changes in SWC caused a reduction of 3.8 Tg C yr-1 in net C sequestration whereas the integrated factors increased net C sequestration by 54.1 Tg C yr-1. Increase in SWC enhanced C sequestration in all ecozones.

Pyrogenic Carbon in soils: a literature-based inventory and a global estimation of its content in soil organic carbon and stocks

NASA Astrophysics Data System (ADS)

Reisser, Moritz; Purves, Ross; Schmidt, Michael W. I.; Abiven, Samuel

2016-08-01

Pyrogenic carbon (PyC) is considered one of the most stable components in soil and can represent more than 30% of total soil organic carbon (SOC). However, few estimates of global PyC stock or distribution exist and thus PyC is not included in any global carbon cycle models, despite its potential major relevance for the soil pool. To obtain a global picture, we reviewed the literature for published PyC content in SOC data. We generated the first PyC database including more than 560 measurements from 55 studies. Despite limitations due to heterogeneous distribution of the studied locations and gaps in the database, we were able to produce a worldwide PyC inventory. We found that global PyC represent on average 13.7% of the SOC and can be even up to 60%, making it one of the largest groups of identifiable compounds in soil, together with polysaccharides. We observed a consistent range of PyC content in SOC, despite the diverse methods of quantification. We tested the PyC content against different environmental explanatory variables: fire and land use (fire characteristics, land use, net primary productivity), climate (temperature, precipitation, climatic zones, altitude) and pedogenic properties (clay content, pH, SOC content). Surprisingly, soil properties explain PyC content the most. Soils with clay content higher than 50% contain significantly more PyC (> 30% of the SOC) than with clay content lower than 5% (< 6% of the SOC). Alkaline soils contain at least 50% more PyC than acidic soils. Furthermore, climatic conditions, represented by climatic zone or mean temperature or precipitation, correlate significantly with the PyC content. By contrast, fire characteristics could only explain PyC content, if site-specific information was available. Datasets derived from remote sensing did not explain the PyC content. To show the potential of this database, we used it in combination with other global datasets to create a global worldwide PyC content and a stock estimation, which resulted in around 200Pg PyC for the uppermost 2 meters. These modelled estimates indicated a clear mismatch between the location of the current PyC studies and the geographical zones where we expect high PyC stocks.

Fractionation between inorganic and organic carbon during the Lomagundi (2.22 2.1 Ga) carbon isotope excursion

NASA Astrophysics Data System (ADS)

Bekker, A.; Holmden, C.; Beukes, N. J.; Kenig, F.; Eglinton, B.; Patterson, W. P.

2008-07-01

The Lomagundi (2.22-2.1 Ga) positive carbon isotope excursion in shallow-marine sedimentary carbonates has been associated with the rise in atmospheric oxygen, but subsequent studies have demonstrated that the carbon isotope excursion was preceded by the rise in atmospheric oxygen. The amount of oxygen released to the exosphere during the Lomagundi excursion is constrained by the average global fractionation between inorganic and organic carbon, which is poorly characterized. Because dissolved inorganic and organic carbon reservoirs were arguably larger in the Paleoproterozoic ocean, at a time of lower solar luminosity and lower ocean redox state, decoupling between these two variables might be expected. We determined carbon isotope values of carbonate and organic matter in carbonates and shales of the Silverton Formation, South Africa and in the correlative Sengoma Argillite Formation, near the border in Botswana. These units were deposited between 2.22 and 2.06 Ga along the margin of the Kaapvaal Craton in an open-marine deltaic setting and experienced lower greenschist facies metamorphism. The prodelta to offshore marine shales are overlain by a subtidal carbonate sequence. Carbonates exhibit elevated 13C values ranging from 8.3 to 11.2‰ vs. VPDB consistent with deposition during the Lomagundi positive excursion. The total organic carbon (TOC) contents range from 0.01 to 0.6% and δ13C values range from - 24.8 to - 13.9‰. Thus, the isotopic fractionation between organic and carbonate carbon was on average 30.3 ± 2.8‰ ( n = 32) in the shallow-marine environment. The underlying Sengoma shales have highly variable TOC contents (0.14 to 21.94%) and δ13C values (- 33.7 to - 20.8‰) with an average of - 27.0 ± 3.0‰ ( n = 50). Considering that the shales were also deposited during the Lomagundi excursion, and taking δ13C values of the overlying carbonates as representative of the δ13C value of dissolved inorganic carbon during shale deposition, a carbon isotope fractionation as large as ~ 37‰ appears to characterize the production of bulk organic matter in the deeper part of the Pretoria Basin at that time. This enhanced fractionation relative to that observed in shallow-water environments likely reflects heterotrophic (secondary) and chemotrophic productivity at and below a pronounced redoxcline, consistent with the euxinic conditions inferred from independent evidence for the deeper part of the Pretoria Basin. Greater variability in organic carbon vs. carbonate carbon isotopic values on the shallow-marine carbonate platform suggests that the carbon cycling was dominated by a large dissolved inorganic carbon reservoir during the Lomagundi excursion. Our study suggests that in contrast to the Late Neoproterozoic and Phanerozoic, when carbon isotope fractionation between carbonate and organic carbon in the open ocean was mostly controlled by primary producers, in the Paleoproterozoic redox-stratified ocean heterotrophic and chemotrophic productivity overprinted a signal of primary productivity below the redoxcline. This strong imprint of heterotrophic and chemotrophic productivity on organic carbon isotope records complicates the reconstruction of spatial patterns and secular trends in the δ13C values of dissolved inorganic carbon in the Paleoproterozoic seawater.

Net Flux of Sedimentary Carbon to the Mantle During the Cenozoic

NASA Astrophysics Data System (ADS)

Clift, P. D.

2017-12-01

Quantification of the long-term cycling of carbon from the mantle to the surface remains contentious despite its importance in governing the climate and biosphere of Earth. Sedimentary carbon represents a significant part of the budget and can be recycled to the mantle if it reaches subduction zones and is not preserved in an accretionary prism. By estimating rates of sediment supply and accretion and taking into account carbonate and carbon contents it appears that 60 Mt/yr is presently being subducted below forearcs. 80% is in the form of carbonate, significantly more than previously estimated. Sedimentary carbon represents around two thirds of the total carbon input at the trenches, the rest being in the igneous crust. An additional 7 Mt/yr is averaged over the Cenozoic as a result of passive margin subduction during continental collision. My revised budget puts the input and output budgets within the range of uncertainties, compared to the previous deficit. Degassing from arc volcanoes and in forearcs totals 55 Mt/yr. A net flux to the mantle is probable. The efficiency of carbon subduction is largely controlled by the carbonate contents of the sediment column, and is partly linked to the latitude of the trench. Accretionary margins are the biggest suppliers of carbon to the mantle wedge, especially Java, Sumatra, Andaman-Burma and Makran because the offscraping is inefficient and the thickness of the trench sediment and trench length are both large. The Western Pacific trenches are negligible sinks of sedimentary carbon.

Sediment Properties as Important Predictors of Carbon Storage in Zostera marina Meadows: A Comparison of Four European Areas

PubMed Central

Dahl, Martin; Deyanova, Diana; Gütschow, Silvia; Asplund, Maria E.; Lyimo, Liberatus D.; Karamfilov, Ventzislav; Santos, Rui; Björk, Mats; Gullström, Martin

2016-01-01

Seagrass ecosystems are important natural carbon sinks but their efficiency varies greatly depending on species composition and environmental conditions. What causes this variation is not fully known and could have important implications for management and protection of the seagrass habitat to continue to act as a natural carbon sink. Here, we assessed sedimentary organic carbon in Zostera marina meadows (and adjacent unvegetated sediment) in four distinct areas of Europe (Gullmar Fjord on the Swedish Skagerrak coast, Askö in the Baltic Sea, Sozopol in the Black Sea and Ria Formosa in southern Portugal) down to ~35 cm depth. We also tested how sedimentary organic carbon in Z. marina meadows relates to different sediment characteristics, a range of seagrass-associated variables and water depth. The seagrass carbon storage varied greatly among areas, with an average organic carbon content ranging from 2.79 ± 0.50% in the Gullmar Fjord to 0.17 ± 0.02% in the area of Sozopol. We found that a high proportion of fine grain size, high porosity and low density of the sediment is strongly related to high carbon content in Z. marina sediment. We suggest that sediment properties should be included as an important factor when evaluating high priority areas in management of Z. marina generated carbon sinks. PMID:27936111

Effects of carbon on phosphorus diffusion in SiGe:C and the implications on phosphorus diffusion mechanisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Yiheng; Xia, Guangrui; Yasuda, Hiroshi

2014-10-14

The use of carbon (C) in SiGe base layers is an important approach to control the base layer dopant phosphorus (P) diffusion and thus enhance PNP heterojunction bipolar transistor (HBT) performance. This work quantitatively investigated the carbon impacts on P diffusion in Si₀.₈₂Ge₀.₁₈:C and Si:C under rapid thermal anneal conditions. The carbon molar fraction is up to 0.32%. The results showed that the carbon retardation effect on P diffusion is less effective for Si₀.₈₂Ge₀.₁₈:C than for Si:C. In Si₀.₈₂Ge₀.₁₈:C, there is an optimum carbon content at around 0.05% to 0.1%, beyond which more carbon incorporation does not retard P diffusionmore » any more. This behavior is different from the P diffusion behavior in Si:C and the B in Si:C and low Ge SiGe:C, which can be explained by the decreased interstitial-mediated diffusion fraction f{sub I}{sup P,SiGe} to 95% as Ge content increases to 18%. Empirical models were established to calculate the time-averaged point defect concentrations and effective diffusivities as a function of carbon and was shown to agree with previous studies on boron, phosphorus, arsenic and antimony diffusion with carbon.« less

Chemometric Study of Trace Elements in Hard Coals of the Upper Silesian Coal Basin, Poland

PubMed Central

Rompalski, Przemysław; Cybulski, Krzysztof; Chećko, Jarosław

2014-01-01

The objective of the study was the analysis of trace elements contents in coals of the Upper Silesian Coal Basin (USCB), which may pose a potential threat to the environment when emitted from coal processing systems. Productive carbon overburden in central and southern zones of the USCB is composed mostly of insulating tertiary formations of a thickness from a few m to 1,100 m, and is represented by Miocene and Pliocene formations. In the data study the geological conditions of the coal seams of particular zones of the USCB were taken into account and the hierarchical clustering analysis was applied, which enabled the exploration of the dissimilarities between coal samples of various zones of the USCB in terms of basic physical and chemical parameters and trace elements contents. Coals of the northern and eastern zones of the USCB are characterized by high average Hg and low average Ba, Cr, and Ni contents, whereas coals of southern and western zones are unique due to high average concentrations of Ba, Co, Cu, Ni, and V. Coals of the central part of the USCB are characterized by the highest average concentration of Mn and the lowest average concentrations of As, Cd, Pb, V, and Zn. PMID:24967424

Capacity estimation of soil organic carbon pools in the intertidal zone of the Bohai Bay

NASA Astrophysics Data System (ADS)

Tian-Yu, Mao; Ting-Ting, Shi; Ya-Juan, Li

2018-03-01

Based on the data obtained from the field survey in the intertidal zone of the Binhai New Area of Tianjin Bay in October 2014, the distribution characteristics of soil organic carbon pool in intertidal zone were studied. The results showed that the highest organic carbon content of soil is 22.913g/kg; the average is 16.304g/kg. The soil organic carbon pool in the intertidal zone is in the 6.58-30.40kg/m3, almost close the level of forest soil in the Binhai New Area. Moreover, close to the surrounding wetland such as Yellow River Estuary or Liaohe River Estuary. In conclusion, the soil carbon storage of the beach tidal flats is higher in the coastal zone, and the carbon storage will be significantly reduced after artificial backfilling.

[Characteristics of carbon storage of Inner Mongolia forests: a review].

PubMed

Yang, Hao; Hu, Zhong-Min; Zhang, Lei-Ming; Li, Sheng-Gong

2014-11-01

Forests in Inner Mongolia account for an important part of the forests in China in terms of their large area and high living standing volume. This study reported carbon storage, carbon density, carbon sequestration rate and carbon sequestration potential of forest ecosystems in Inner Mongolia using the biomass carbon data from the related literature. Through analyzing the data of forest inventory and the generalized allometric equations between volume and biomass, previous studies had reported that biomass carbon storage of the forests in Inner Mongolia was about 920 Tg C, which was 12 percent of the national forest carbon storage, the annual average growth rate was about 1.4%, and the average of carbon density was about 43 t · hm(-2). Carbon storage and carbon density showed an increasing trend over time. Coniferous and broad-leaved mixed forest, Pinus sylvestris var. mongolica forest and Betula platyphylla forest had higher carbon sequestration capacities. Carbon storage was reduced due to human activities such as thinning and clear cutting. There were few studies on carbon storage of the forests in Inner Mongolia with focus on the soil, showing that the soil car- bon density increased with the stand age. Study on the carbon sequestration potential of forest ecosystems was still less. Further study was required to examine dynamics of carbon storage in forest ecosystems in Inner Mongolia, i. e., to assess carbon storage in the forest soils together with biomass carbon storage, to compute biomass carbon content of species organs as 45% in the allometric equations, to build more species-specific and site-specific allometric equations including root biomass for different dominant species, and to take into account the effects of climate change on carbon sequestration rate and carbon sequestration potential.

Chemistry of modern sediments in a hypersaline lagoon, north of Jeddah, Red Sea

NASA Astrophysics Data System (ADS)

El-Sayed, Mahmoud Kh.

1987-10-01

Previous studies of modern peritidal sedimentary environments of the Red Sea, such as hypersaline lagoons and sea-marginal flats, have concentrated on its northern part, particularly in the Gulf of Aqaba. However, little is known about lagoon sediments in other localities along the Red Sea coastal stretches. This paper deals with the chemical characteristics of the sediments of a hypersaline (Ras Hatiba) lagoon, north of Jeddah, Saudi Arabia. The chemistry of hypersaline lagoon sediments is considerably changed following the modifications to the water chemistry by evaporation and precipitation. Ras Hatiba lagoon is a hypersaline elongated water body connected to the Red Sea by a narrow and shallow opening. The total area of the lagoon is c. 30 km 2. Coarse bioclastic sands are dominant in the lagoon and mostly surround lithified calcareous grounds. However, fine silt and clay sediments are present in separate patches. The sediments are rich in carbonates (average 78·5%) and organic carbon (average 7·3%), although they are negatively correlated. Calcium (average 25·1%) and magnesium (average 10·8‰) show a similar distribution pattern in the lagoon sediments. Strontium (average 5·2‰) is positively correlated with calcium. Sodium and potassium are relatively highly concentrated in the sediments (average 118 ppm and 173 ppm, respectively). Magnesium and strontium are of prime importance in the process of mineralization and diagenesis. The sabkha formation surrounding the lagoon is of low carbonate and organic carbon content, compared with the lagoon sediments, whilst it is characterized by high magnesium, sodium and potassium concentrations. Ras Hatiba lagoon sediments and sabkha resemble those of the northern Red Sea in the Gulfs of Aqaba and Suez and the Arabian Gulf in their major sedimentological and chemical characteristics.

Effect of synthesis conditions on the nanopowder properties of Ce{sub 0.9}Zr{sub 0.1}O{sub 2}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zimicz, M.G.; Fabregas, I.O.; Lamas, D.G.

Graphical abstract: . The synthesis of nanocrystalline Ce{sub 0.9}Zr{sub 0.1}O{sub 2} powders via the gel-combustion method, using different fuels, and following either stoichiometric or non-stoichiometric pH-controlled routes is investigated. Research highlights: {yields} All samples exhibited the fluorite-type crystal structure, nanometric average crystallite size and negligible carbon content. {yields} Synthesis conditions strongly affect the average crystallite size, the degree of agglomeration, the specific surface area and the pore volume. {yields} Our results indicate that, by controlling the synthesis conditions it is possible to obtain solids with custom-made morphological properties. -- Abstract: In this work, the synthesis of nanocrystalline Ce{sub 0.9}Zr{sub 0.1}O{submore » 2} powders via the gel-combustion method, using different fuels, and following either stoichiometric or non-stoichiometric pH-controlled routes is investigated. The objective is to evaluate the effect of synthesis conditions on the textural and morphological properties, and the crystal structure of the synthesized materials. The solids were characterized by nitrogen physisorption, Scanning Electron Microscopy (SEM), X-ray powder diffraction (XPD), and Carbon-Hydrogen-Nitrogen Elemental Analysis (CHN). All the powders exhibited nanometric crystallite size, fluorite-type structure and negligible carbon content. Synthesis conditions strongly affect the average crystallite size, the degree of agglomeration, the specific surface area and the pore volume. Our results indicate that, by controlling the synthesis conditions it is possible to obtain solids with custom-made morphological properties.« less

[Carbon sequestration in soil particle-sized fractions during reversion of desertification at Mu Us Sand land.

PubMed

Ma, Jian Ye; Tong, Xiao Gang; Li, Zhan Bin; Fu, Guang Jun; Li, Jiao; Hasier

2016-11-18

The aim of this study was to investigate the effects of carbon sequestration in soil particle-sized fractions during reversion of desertification at Mu Us Sand Land, soil samples were collected from quicksand land, semifixed sand and fixed sand lands that were established by the shrub for 20-55 year-old and the arbor for 20-50 year-old at sand control region of Yulin in Northern Shaanxi Province. The dynamics and sequestration rate of soil organic carbon (SOC) associated with sand, silt and clay were measured by physical fractionation method. The results indicated that, compared with quicksand area, the carbon content in total SOC and all soil particle-sized fractions at bothsand-fixing sand forest lands showed a significant increasing trend, and the maximum carbon content was observed in the top layer of soils. From quicksand to fixed sand land with 55-year-old shrub and 50-year-old arbor, the annual sequestration rate of carbon stock in 0-5 cm soil depth was same in silt by 0.05 Mg·hm -2 ·a -1 . The increase rate of carbon sequestration in sand was 0.05 and 0.08 Mg·hm -2 ·a -1 , and in clay was 0.02 and 0.03 Mg·hm -2 ·a -1 at shrubs and arbors land, respectively. The increase rate of carbon sequestration in 0-20 cm soil layer for all the soil particles was averagely 2.1 times as that of 0-5 cm. At the annual increase rate of carbon, the stock of carbon in sand, silt and clay at the two fixed sand lands were increased by 6.7, 18.1 and 4.4 times after 50-55 year-old reversion of quicksand land to fixed sand. In addition, the average percentages that contributed to accumulation of total SOC by different particles in 0-20 cm soil were in the order of silt carbon (39.7%)≈sand carbon (34.6%) > clay carbon (25.6%). Generally, the soil particle-sized fractions had great carbon sequestration potential during reversion of desertification in Mu Us Sand Land, and the slit and sand were the main fractions for carbon sequestration at both fixed sand lands.

Changes in Soil Carbon Storage After Cultivation

DOE Data Explorer

Mann, L. K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2004-01-01

Previously published data from 625 paired soil samples were used to predict carbon in cultivated soil as a function of initial carbon content. A 30-cm sampling depth provided a less variable estimate (r² = 0.9) of changes in carbon than a 15-cm sampling depth (r² = 0.6). Regression analyses of changes in carbon storage in relation to years of cultivation confirmed that the greatest rates of change occurred in the first 20 y. An initial carbon effect was present in all analyses: soils very low in carbon tended to gain slight amounts of carbon after cultivation, but soils high in carbon lost at least 20% during cultivation. Carbon losses from most agricultural soils are estimated to average less than 20% of initial values or less than 1.5 kg/m² within the top 30 cm. These estimates should not be applied to depths greater than 30 cm and would be improved with more bulk density information and equivalent sample volumes.

C/O atomic ratios in micrometer-size crushed grains from Antarctic micrometeorites and two carbonaceous meteorites

NASA Technical Reports Server (NTRS)

Perreau, M.; Engrand, C.; Maurette, Michel; Kurat, G.; Presper, TH.

1993-01-01

Antarctic micrometeorites (AMM's) have similarities (but also differences) with primitive meteorites, such as unequilibrated mineral assemblages. To further assess such similarities, we have measured the carbon content of micrometeorites and meteorites (Orgueil and Murchison), as determined in a random selection of micrometer-size crushed grain, with an analytical transmission electron microscope. Such analyses yield the C/O atomic ratio, the major and minor elements contents, and the textural features of the grains on a scale of approx. equal to 100 nanometers. An important proportion of micrometeorites from both the 100-400 micron and the 50-100 micron size fractions contains much more carbon than CI chondrite Orgueil. The average C-content of all micrometeorites in these two size fractions amount to approximately 1.8 x CI, and approximately 0.8 x CI, respectively (CI refers to the bulk C-content of Orgueil, of about 3.5 percent by weight). Carbon is usually not homogeneously distributed in the micrometeorite but is concentrated in C-rich grains. So far, most of these grains are amorphous, and seem to be associated with an oxidized Fe-rich phase (possibly a variety of 'dirty' magnetite). About 5 percent of them have the composition of 'COPS', a phase additionally enriched in O, P, and S.

Optimization of calcium carbonate content on synthesis of aluminum foam and its compressive strength characteristic

NASA Astrophysics Data System (ADS)

Sutarno, Nugraha, Bagja; Kusharjanto

2017-01-01

One of the most important characteristic of aluminum foam is compressive strength, which is reflected by its impact energy and Young's modulus. In the present research, optimization of calcium carbonate (CaCO3) content in the synthesized aluminum foam in order to obtain the highest compressive strength was carried out. The results of this study will be used to determine the CaCO3 content synthesis process parameter in pilot plant scale production of an aluminum foam. The experiment was performed by varying the concentration of calcium carbonate content, which was used as foaming agent, at constant alumina concentration (1.5 wt%), which was added as stabilizer, and temperature (725°C). It was found that 4 wt% CaCO3 gave the lowest relative density, which was 0.15, and the highest porosity, which was 85.29%, and compressive strength of as high as 0.26 Mpa. The pore morphology of the obtained aluminum foam at such condition was as follow: the average pore diameter was 4.42 mm, the wall thickness minimum of the pore was 83.24 µm, roundness of the pore was 0.91. Based on the fractal porosity, the compressive strength was inversely proportional to the porosity and huddled on a power law value of 2.91.

A cost-efficient method to assess carbon stocks in tropical peat soil

NASA Astrophysics Data System (ADS)

Warren, M. W.; Kauffman, J. B.; Murdiyarso, D.; Anshari, G.; Hergoualc'h, K.; Kurnianto, S.; Purbopuspito, J.; Gusmayanti, E.; Afifudin, M.; Rahajoe, J.; Alhamd, L.; Limin, S.; Iswandi, A.

2012-11-01

Estimation of belowground carbon stocks in tropical wetland forests requires funding for laboratory analyses and suitable facilities, which are often lacking in developing nations where most tropical wetlands are found. It is therefore beneficial to develop simple analytical tools to assist belowground carbon estimation where financial and technical limitations are common. Here we use published and original data to describe soil carbon density (kgC m-3; Cd) as a function of bulk density (gC cm-3; Bd), which can be used to rapidly estimate belowground carbon storage using Bd measurements only. Predicted carbon densities and stocks are compared with those obtained from direct carbon analysis for ten peat swamp forest stands in three national parks of Indonesia. Analysis of soil carbon density and bulk density from the literature indicated a strong linear relationship (Cd = Bd × 495.14 + 5.41, R2 = 0.93, n = 151) for soils with organic C content > 40%. As organic C content decreases, the relationship between Cd and Bd becomes less predictable as soil texture becomes an important determinant of Cd. The equation predicted belowground C stocks to within 0.92% to 9.57% of observed values. Average bulk density of collected peat samples was 0.127 g cm-3, which is in the upper range of previous reports for Southeast Asian peatlands. When original data were included, the revised equation Cd = Bd × 468.76 + 5.82, with R2 = 0.95 and n = 712, was slightly below the lower 95% confidence interval of the original equation, and tended to decrease Cd estimates. We recommend this last equation for a rapid estimation of soil C stocks for well-developed peat soils where C content > 40%.

Aged Riverine Particulate Organic Carbon in Four UK Catchments

NASA Astrophysics Data System (ADS)

Adams, Jessica; Tipping, Edward; Bryant, Charlotte; Helliwell, Rachel; Toberman, Hannah; Quinton, John

2016-04-01

The riverine transport of particulate organic matter (POM) is a significant flux in the carbon cycle, and affects macronutrients and contaminants. We used radiocarbon to characterise POM at 9 riverine sites of four UK catchments (Avon, Conwy, Dee, Ribble) over a one-year period. High-discharge samples were collected on three or four occasions at each site. Suspended particulate matter (SPM) was obtained by centrifugation, and the samples were analysed for carbon isotopes. Concentrations of SPM and SPM organic carbon (OC) contents were also determined, and were found to have a significant negative correlation. For the 7 rivers draining predominantly rural catchments, PO14C values, expressed as percent modern carbon absolute (pMC), varied little among samplings at each site, and there was no significant difference in the average values among the sites. The overall average PO14C value for the 7 sites of 91.2 pMC corresponded to an average age of 680 14C years, but this value arises from the mixing of differently-aged components, and therefore significant amounts of organic matter older than the average value are present in the samples. Although topsoil erosion is probably the major source of the riverine POM, the average PO14C value is appreciably lower than topsoil values (which are typically 100 pMC). This is most likely explained by inputs of older subsoil OC from bank erosion, or the preferential loss of high-14C topsoil organic matter by mineralisation during riverine transport. The significantly lower average PO14C of samples from the River Calder (76.6 pMC), can be ascribed to components containing little or no radiocarbon, derived either from industrial sources or historical coal mining, and this effect is also seen in the River Ribble, downstream of its confluence with the Calder. At the global scale, the results significantly expand available information for PO14C in rivers draining catchments with low erosion rates.

Carbon export and cycling by the Yukon, Tanana, and Porcupine rivers, Alaska, 2001-2005

USGS Publications Warehouse

Striegl, Robert G.; Dornblaser, Mark M.; Aiken, George R.; Wickland, Kimberly P.; Raymond, Peter A.

2007-01-01

Loads and yields of dissolved and particulate organic and inorganic carbon (DOC, POC, DIC, PIC) were measured and modeled at three locations on the Yukon River (YR) and on the Tanana and Porcupine rivers (TR, PR) in Alaska during 2001–2005. Total YR carbon export averaged 7.8 Tg C yr−1, 30% as OC and 70% as IC. Total C yields (0.39–1.03 mol C m−2 yr−1) were proportional to water yields (139–356 mm yr−1; r2 = 0.84) at all locations. Summer DOC had an aged component (fraction modern (FM) = 0.94–0.97), except in the permafrost wetland‐dominated PR, where DOC was modern. POC had FM = 0.63–0.70. DOC had high concentration, high aromaticity, and high hydrophobic content in spring and low concentration, low aromaticity, and high hydrophilic content in winter. About half of annual DOC export occurred during spring. DIC concentration and isotopic composition were strongly affected by dissolution of suspended carbonates in glacial meltwater during summer.

Influence of growth conditions and surface reaction byproducts on GaN grown via metal organic molecular beam epitaxy: Toward an understanding of surface reaction chemistry

NASA Astrophysics Data System (ADS)

Pritchett, David; Henderson, Walter; Burnham, Shawn D.; Doolittle, W. Alan

2006-04-01

The surface reaction byproducts during the growth of GaN films via metal organic molecular beam epitaxy (MOMBE) were investigated as a means to optimize material properties. Ethylene and ethane were identified as the dominant surface reaction hydrocarbon byproducts, averaging 27.63% and 7.15% of the total gas content present during growth. Intense ultraviolet (UV) photoexcitation during growth was found to significantly increase the abundance of ethylene and ethane while reducing the presence of H2 and N2. At 920°C, UV excitation was shown to enhance growth rate and crystalline quality while reducing carbon incorporation. Over a limited growth condition range, a 4.5×1019-3.4×1020 cm-3 variation in carbon incorporation was achieved at constant high vacuum. Coupled with growth rate gains, UV excitation yielded films with ˜58% less integrated carbon content. Structural material property variations are reported for various ammonia flows and growth temperatures. The results suggest that high carbon incorporation can be achieved and regulated during MOMBE growth and that in-situ optimization through hydrocarbon analysis may provide further enhancement in the allowable carbon concentration range.

Weak hydrothermal carbonation of the Ongeluk volcanics: evidence for low CO2 concentrations in seawater and atmosphere during the Paleoproterozoic global glaciation

NASA Astrophysics Data System (ADS)

Shibuya, Takazo; Komiya, Tsuyoshi; Takai, Ken; Maruyama, Shigenori; Russell, Michael J.

2017-12-01

It was previously revealed that the total CO2 concentration in seawater decreased during the Late Archean. In this paper, to assess the secular change of total CO2 concentration in seawater, we focused on the Paleoproterozoic era when the Earth experienced its first recorded global glaciation. The 2.4 Ga Ongeluk Formation outcrops in the Kaapvaal Craton, South Africa. The formation consists mainly of submarine volcanic rocks that have erupted during the global glaciation. The undeformed lavas are mostly carbonate-free but contain rare disseminated calcites. The carbon isotope ratio of the disseminated calcite (δ13Ccc vs. VPDB) ranges from - 31.9 to - 13.2 ‰. The relatively low δ13Ccc values clearly indicate that the carbonation was partially contributed by 13C-depleted CO2 derived from decomposition of organic matter beneath the seafloor. The absence of δ13Ccc higher than - 13.2‰ is consistent with the exceptionally 13C-depleted CO2 in the Ongeluk seawater during glaciation. The results suggest that carbonation occurred during subseafloor hydrothermal circulation just after the eruption of the lavas. Previously, it was reported that the carbonate content in the uppermost subseafloor crust decreased from 3.2 to 2.6 Ga, indicating a decrease in total CO2 concentration in seawater during that time. However, the average CO2 (as carbonate) content in the Ongeluk lavas (< 0.001 wt%) is much lower than those of 2.6 Ga representatives and even of modern equivalents. This finding suggests that the total CO2 concentration in seawater further decreased during the period between 2.6 and 2.4 Ga. Thus, the very low content of carbonate in the Ongeluk lavas is probable evidence for the extremely low CO2 concentration in seawater during the global glaciation. Considering that the carbonate content of the subseafloor crusts also shows a good correlation with independently estimated atmospheric pCO2 levels through the Earth history, it seem highly likely that the low carbonate content in the Ongeluk lavas reflects the low atmospheric pCO2 at that time. We conclude that the continuous decrease in CO2 concentration of seawater/atm. from 3.2 Ga was one of the contributing factors to the Paleoproterozoic global glaciation.

Mapping Soil Carbon in the Yukon Kuskokwim River Delta Alaska

NASA Astrophysics Data System (ADS)

Natali, S.; Fiske, G.; Schade, J. D.; Mann, P. J.; Holmes, R. M.; Ludwig, S.; Melton, S.; Sae-lim, N.; Jardine, L. E.; Navarro-Perez, E.

2017-12-01

Arctic river deltas are hotspots for carbon storage, occupying <1% of the pan-Arctic watershed but containing >10% of carbon stored in arctic permafrost. The Yukon Kuskokwim (YK) Delta, Alaska is located in the lower latitudinal range of the northern permafrost region in an area of relatively warm permafrost that is particularly vulnerable to warming climate. Active layer depths range from 50 cm on peat plateaus to >100 cm in wetland and aquatic ecosystems. The size of the soil organic carbon pool and vulnerability of the carbon in the YK Delta is a major unknown and is critically important as climate warming and increasing fire frequency may make this carbon vulnerable to transport to aquatic and marine systems and the atmosphere. To characterize the size and distribution of soil carbon pools in the YK Delta, we mapped the land cover of a 1910 km2 watershed located in a region of the YK Delta that was impacted by fire in 2015. The map product was the result of an unsupervised classification using the Weka K Means clustering algorithm implemented in Google's Earth Engine. Inputs to the classification were Worldview2 resolution optical imagery (1m), Arctic DEM (5m), and Sentinel 2 level 1C multispectral imagery, including NDVI, (10 m). We collected 100 soil cores (0-30 cm) from sites of different land cover and landscape position, including moist and dry peat plateaus, high and low intensity burned plateaus, fens, and drained lakes; 13 lake sediment cores (0-50 cm); and 20 surface permafrost cores (to 100 cm) from burned and unburned peat plateaus. Active layer and permafrost soils were analyzed for organic matter content, soil moisture content, and carbon and nitrogen pools (30 and 100 cm). Soil carbon content varied across the landscape; average carbon content values for lake sediments were 12% (5- 17% range), fens 26% (9-44%), unburned peat plateaus 41% (34-44%), burned peat plateaus 19% (7-34%). These values will be used to estimate soil carbon pools, which will be applied to the spatial extent of each landcover class in our map, yielding a watershed-wide and spatially explicit map of soil carbon in the YK Delta. This map will provide the basis for understanding where carbon is stored in the watershed and the vulnerability of that carbon to climate change and fire.

A quarter-million years of paleoenvironmental change at Bear Lake, Utah and Idaho

USGS Publications Warehouse

Kaufman, D.S.; Bright, Jordon; Dean, W.E.; Rosenbaum, J.G.; Moser, K.; Anderson, R. Scott; Colman, Steven M.; Heil, C.W.; Jiménez-Moreno, Gonzalo; Reheis, M.C.; Simmons, K.R.

2009-01-01

A continuous, 120-m-long core (BL00-1) from Bear Lake, Utah and Idaho, contains evidence of hydrologic and environmental change over the last two glacial-interglacial cycles. The core was taken at 41.95??N, 111.31??W, near the depocenter of the 60-m-deep, spring-fed, alkaline lake, where carbonate-bearing sediment has accumulated continuously. Chronological control is poor but indicates an average sedimentation rate of 0.54 mm yr-1. Analyses have been completed at multi-centennial to millennial scales, including (in order of decreasing temporal resolution) sediment magnetic properties, oxygen and carbon isotopes on bulk-sediment carbonate, organic- and inorganiccarbon contents, palynology; mineralogy (X-ray diffraction), strontium isotopes on bulk carbonate, ostracode taxonomy, oxygen and carbon isotopes on ostracodes, and diatom assemblages. Massive silty clay and marl constitute most of the core, with variable carbonate content (average = 31 ?? 19%) and oxygen-isotopic values (??18O ranging from -18??? to -5??? in bulk carbonate). These variations, as well as fluctuations of biological indicators, reflect changes in the water and sediment discharged from the glaciated headwaters of the dominant tributary, Bear River, and the processes that influenced sediment delivery to the core site, including lake-level changes. Although its influence has varied, Bear River has remained a tributary to Bear Lake during most of the last quarter-million years. The lake disconnected from the river and, except for a few brief excursions, retracted into a topographically closed basin during global interglaciations (during parts of marine isotope stages 7, 5, and 1). These intervals contain up to 80% endogenic aragonite with high ??18O values (average = -5.8 ?? 1.7???), indicative of strongly evaporitic conditions. Interglacial intervals also are dominated by small, benthic/tychoplanktic fragilarioid species indicative of reduced habitat availability associated with low lake levels, and they contain increased high-desert shrub and Juniperus pollen and decreased forest and forest-woodland pollen. The 87Sr 86Sr values (>0.7100) also increase, and the ratio of quartz to dolomite decreases, as expected in the absence of Bear River in flow. The changing paleoenvironments inferred from BL00-1 generally are consistent with other regional and global records of glacialinterglacial fluctuations; the diversity of paleoenvironmental conditions inferred from BL00-1 also reflects the influence of catchment-scale processes. Copyright ?? 2009 The Geological Society of America.

Frozen peatlands: carbon store and the climate change

NASA Astrophysics Data System (ADS)

Ogneva, Olga; Matyshak, George; Tarkhov, Matvey

2017-04-01

Peatlands soils in the northern permafrost region store approximately 40% of total Earth's soils carbon. These soils develop under the influence of cryogenic processes especially such as freeze-thaw and cryoturbations. Climate change predictions suggest that the frequency of soil freeze-thaw cycles (FTCs) will increase in cool temperate and other high-latitude regions. This trend may cause a response in organic matter decomposition rate - that will result in significant changes of greenhouse gases emission (CO2, CH4). For further predictions improvement of soils response to global climate changes it is necessary to estimate the impact of FTCs in permafrost soils on organic matter decomposition. We investigated the effects of FTCs on microbial biomass, basal respiration, metabolic quotient and dissolved organic matter (DOM) content (carbon - DOC and nitrogen - DON) in frozen peatlands soils by laboratory modelling experiment. Frozen peatlands from the north of Western Siberia in Nadym area (N65°19', E72°53'), in a zone of discontinuous permafrost were studied. The soil cover of these formations is represented by a complex of Typic Histoturbels (Turbic Cryosol) and Typic Historthels (Cryic Histosols). Peat profiles of both soil types were divided into horizons due to decomposition degree (from 15 to 55-60%), age (from 1000 to 5700 yrs) and botanic composition (oligotrophic, mesotrophic, eutrophic). During the experiment, first group of samples of peat horizons (field moisture content) were subjected for 10 times to 3-day FTCs at the temperature of -10 and +4 ° C. In the second group of peat samples were incubated at +4 ° C (with no freeze-thaw). It was established that all studied microbial properties were inversely proportional with decomposition degree of peat, except metabolic quotient. Our results illustrate that microbial activity, estimated by BR, shows resistance to FTCs and doesn't significantly differ after FTCs an average. Microbial biomass (carbon and nitrogen) as well as BR doesn't differ too. The most intensive response to FTCs shows DOM content value which was 1.5 times higher on average in samples after FTCs in comparison with control samples. We suppose that increase of FTCs frequency in soil will result in significant acceleration mineralization of peat. Because these processes exert disruptive effects on soil organic matter, provide converting carbon from pool into forms available for microbial communities, thus involving stored carbon into the carbon turnover.

Enhanced photocatalytic activity of Fe-doped TiO2 coated on N-doped activated carbon composites for photocatalytic degradation of dyeing wastewater

NASA Astrophysics Data System (ADS)

Zhou, Jie; Zhu, Beibei; Wang, Lu; Li, Ya; Qiao, Qichen

2017-10-01

Fe-doped TiO2 coated on N-doped activated carbon (Fe-TiO2/N-AC, FTNA) composites were synthesized simply by a straightforward two-step procedure. The obtained materials were characterized by X-ray diffractometry (XRD), N2 adsorption-desorption, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and FT-IR spectroscopies. Through the degradation of dyeing wastewater, the photocatalytic activity of FTNA was investigated under ultraviolet light irradiation. The results showed that containing N functional groups were successfully introduced onto the surface of the activated carbon. Compared with Fe-TiO2/AC (FTA), FTNA with average particle size of TiO2 13.6 nm and surface area 1007.89 m2/g showed a higher photoactivity. Additionally, for the photocatalytic degradation of dyeing wastewater, the optimum N content and catalyst content were 0.8% and 5g/L, respectively. Moreover, the photoactivity and photo stability of the catalyst after many runs was also evaluated.

Acidity in organic horizons of arctic soils on the Barents Sea coast

NASA Astrophysics Data System (ADS)

Shamrikova, E. V.; Deneva, S. V.; Kubik, O. S.; Punegov, V. V.; Kyz”yurova, E. V.; Bobrova, Yu. I.; Zueva, O. M.

2017-11-01

Parameters of water and KCl extracts from organic horizons of arctic soils on the coast of Khaipudyr Bay of the Barents Sea, in which the values of pH are 3.8-4.3 and 2.7-3.5, respectively, have been compared. It has been found that the content of water-extractable organic carbon is 0.2-0.5 g/dm3; the contents of low-molecular-weight carbohydrates and acids are 1-24 and 6 mg/dm3, respectively, and the content of Fe3+ ions is 1-4 mmol/dm3. The increase in the ionic strength of solution reduces the extraction efficiency of total organic carbon in 1.2 times and that of acids and carbohydrates in 3 times on the average at the simultaneous increase in the content of iron ions in the liquid phase in 7-15 times. It has been shown that organic acids and iron compounds are the main sources of acidity in salt extracts from organic soil horizons. The low contents of Ca2+ and Mg2+, which participate in the neutralization of acids, favor the high acidity of the studied horizons.

Carbonaceous content and water-soluble organic functionality of atmospheric aerosols at a semi-rural New England location

NASA Astrophysics Data System (ADS)

Shakya, Kabindra M.; Place, Philip F., Jr.; Griffin, Robert J.; Talbot, Robert W.

2012-02-01

Ambient aerosol samples (n = 287) collected at a semi-rural location, Thompson Farm (TF) in Durham, New Hampshire, from August 2007 to 2008 exhibited seasonal variation, characterized by the largest total carbon (TC) concentrations during winter (3.74 ± 2.55 μg C m-3) and the smallest during summer (1.21 ± 1.22 μg C m-3). On average, 92% of TC was organic (OC), of which 69% on average was observed to be water-soluble (WSOC). This study focuses on characterizing the WSOC functional groups using Proton Nuclear Magnetic Resonance spectroscopy on a subset of the samples (n = 108). Three aliphatic groups (H-C, H-C-C=, and H-C-O) are estimated to account for 79% of the characterized WSOC carbon mass. Pure aliphatic (H-C), oxygenated aliphatic (H-C-O), and unsaturated aliphatic (H-C-C=) groups were the dominant functional groups contributing to an average of 31%, 25%, and 23% of the WSOC carbon mass, respectively. The arylic group contributed an average of 21% of the WSOC carbon mass but exhibited large seasonal variation compared to the other groups. Precipitation affected mainly the WSOC and the H-C-C= functional group, which showed consistent decreases following rainfall events. Strong correlation between elemental carbon and OC and the dominance of air masses from the continental Midwest during winter shows that primary emissions (from local heating or industrial emissions) were the main sources during winter. Air masses originating from the continental Midwest were associated with the high levels of EC, primary OC, and H-C-O at TF. In contrast to winter, enhanced secondary formation and processed aerosols were dominant during other seasons.

Carbon decomposition process of the residual biomass in the paddy soil of a single-crop rice field

NASA Astrophysics Data System (ADS)

Okada, K.; Iwata, T.

2014-12-01

In cultivated fields, residual organic matter is plowed into soil after harvest and decaying in fallow season. Greenhouse gases such as CO2 and CH4 is generated by the decomposition of the substantial organic matter and released into the atmosphere. In some fields, open burning is carried out by tradition, when carbon in residual matter is released into atmosphere as CO2. However, burning effect on carbon budget between crop lands and atmosphere is not entirely considered yet. In this study, coarse organic matter (COM) in paddy soil of a single-crop rice field was sampled on regular intervals between January, 2011 and August, 2014 The amount of carbon release from residual matter was estimated by analyzing of the variations in carbon content of COM. Effects of soil temperature (Ts) and soil water content (SWC) at the paddy field on the rate of carbon decomposition was investigated. Though decreasing rate of COM was much smaller in winter season, it is accelerated at the warming season between April and June every year. Decomposition was resisted for next rice cultivated season despite of highest soil temperature. In addition, the observational field was divided into two areas, and three time open burning experiments were conducted in November, 2011, 2012, and 2013. In each year, three sampling surveys, or plants before harvest and residuals before and after the burning experiment, were done. From these surveys, it is suggested that about 48±2% of carbon contents of above-ground plant was yield out as grain by harvest, and about 27±2% of carbon emitted as CO2 by burning. Carbon content of residuals plowed into soil after the harvest was estimated 293±1 and 220±36gC/m2 in no-burned and burned area, respectively, based on three-years average. It is estimated that 70 and 60% of the first input amount of COM was decomposed after a year in no-burned and burned area, respectively.

Cycling of Volatiles and Stable Isotopes During High-P Subduction Dehydration of Serpentinite

NASA Astrophysics Data System (ADS)

Alt, J.; Garrido, C. J.; Shanks, W. C.; Turchyn, A. V.; López-Sánchez-Vizcaíno, V.; Gómez-Pugnaire, M.

2009-12-01

We present volatile contents and stable isotope compositions of high-P antigorite serpentinites and their chlorite-harzburgite dehydration products from the Cerro del Almirez complex, Spain. The serpentinites are former Tethyan seafoor consisting of antigorite with olivine, diopside, chlorite, magnetite, tremolite, and Ti-clinohumite, dehydrated to chlorite-harzburites comprising spinifex-like olivine + orthopyroxene, with chlorite, tremolite, and magnetite, at T> 650°C and P>2 GPa. The serpentinites have elevated H2O, S, and C contents, averaging (n=10) 1000 ppm S and 10 wt% H2O, and with 180-1280 ppm total C. Bulk δ18O values of 7.9-9.1‰ and δD= -49 to -61‰ are consistent with serpentinization by seawater at 50-100°C. The high sulfide contents and preliminary δ34S analyses of ~10‰ likely reflect microbial reduction of seawater sulfate, and δ13C (total C) values of -10.9 to -20.2‰ are consistent with the presence of an organic carbon component. These data and processes are similar to those for modern seafloor serpentinites. High-P dehydration of the serpentinites resulted in loss of about half of their H2O and S: chlorite-harzburgites (n=11) average 5.7 wt% H2O and 610 ppm S. The δ34S (-5.1 to 10.2‰) and δ18O (6.4-9.5‰) of the metamorphic harzburgites are unchanged from serpentinite, but hydrogen isotopes are fractionated during dehydration, from serpentinite δD values around -55‰ to chlorite-harzburgite values of ~ -70 to -90‰. Carbon contents and δ13C values of the two rock types overlap, with a broad trend of decreasing C contents and δ13C, from ~1200 to 200 ppm and -9.6 to -20.3‰, perhaps reflecting loss of CO2. Our results indicate: 1) significant uptake of H2O, S and C during serpentinization on the seafloor; 2) that recycling of serpentinites to high P and T results in loss of isotopically fractionated sulfur, water and possibly carbon to the sub-arc mantle; and 3) that fractionated sulfur, water and carbon in serpentinite dehydration products can be recycled into the mantle where they can contribute to isotope heterogeneities.

Patterns of plant carbon, nitrogen, and phosphorus concentration in relation to productivity in China’s terrestrial ecosystems

PubMed Central

Xu, Wenting; Zhou, Guoyi; Bai, Yongfei; Li, Jiaxiang; Tang, Xuli; Liu, Qing; Ma, Wenhong; Xiong, Gaoming; He, Honglin; Guo, Yanpei; Guo, Qiang; Zhu, Jiangling; Han, Wenxuan; Hu, Huifeng; Fang, Jingyun; Xie, Zongqiang

2018-01-01

Plant nitrogen (N) and phosphorus (P) content regulate productivity and carbon (C) sequestration in terrestrial ecosystems. Estimates of the allocation of N and P content in plant tissues and the relationship between nutrient content and photosynthetic capacity are critical to predicting future ecosystem C sequestration under global change. In this study, by investigating the nutrient concentrations of plant leaves, stems, and roots across China’s terrestrial biomes, we document large-scale patterns of community-level concentrations of C, N, and P. We also examine the possible correlation between nutrient content and plant production as indicated by vegetation gross primary productivity (GPP). The nationally averaged community concentrations of C, N, and P were 436.8, 14.14, and 1.11 mg·g−1 for leaves; 448.3, 3.04 and 0.31 mg·g−1 for stems; and 418.2, 4.85, and 0.47 mg·g−1 for roots, respectively. The nationally averaged leaf N and P productivity was 249.5 g C GPP·g-1 N·y−1 and 3,157.9 g C GPP·g–1 P·y−1, respectively. The N and P concentrations in stems and roots were generally more sensitive to the abiotic environment than those in leaves. There were strong power-law relationships between N (or P) content in different tissues for all biomes, which were closely coupled with vegetation GPP. These findings not only provide key parameters to develop empirical models to scale the responses of plants to global change from a single tissue to the whole community but also offer large-scale evidence of biome-dependent regulation of C sequestration by nutrients. PMID:29666316

Effect of Filler Type on the Properties of Rigid Polyurethane Foams at a Cryogenic Temperature

NASA Astrophysics Data System (ADS)

Yakushin, V.; Cabulis, U.; Sevastyanova, I.

2015-09-01

The effect of filler type and mass percentage on the properties of low-density rigid polyurethane foams at a temperature of 77K was investigated. The mechanical properties of foams of density 55-90 kg/m3 filled with milled carbon fibers of average length of 100 and 60 μm and hollow glass microspheres of average diameter of 65 μm were compared. A considerable increase in the compressive elastic modulus in the foam rise direction with increasing filler content was observed. The compression strength of the foams in the parallel and perpendicular directions at the cryogenic temperature decreased upon introducing the milled carbon fibers of either type. The compression strength of the foams of density 90 kg/m3 somewhat increased only upon introducing the glass microspheres.

Impact of deforestation on soil carbon stock and its spatial distribution in the Western Black Sea Region of Turkey.

PubMed

Kucuker, Mehmet Ali; Guney, Mert; Oral, H Volkan; Copty, Nadim K; Onay, Turgut T

2015-01-01

Land use management is one of the most critical factors influencing soil carbon storage and the global carbon cycle. This study evaluates the impact of land use change on the soil carbon stock in the Karasu region of Turkey which in the last two decades has undergone substantial deforestation to expand hazelnut plantations. Analysis of seasonal soil data indicated that the carbon content decreased rapidly with depth for both land uses. Statistical analyses indicated that the difference between the surface carbon stock (defined over 0-5 cm depth) in agricultural and forested areas is statistically significant (Agricultural = 1.74 kg/m(2), Forested = 2.09 kg/m(2), p = 0.014). On the other hand, the average carbon stocks estimated over the 0-1 m depth were 12.36 and 12.12 kg/m(2) in forested and agricultural soils, respectively. The carbon stock (defined over 1 m depth) in the two land uses were not significantly different which is attributed in part to the negative correlation between carbon stock and bulk density (-0.353, p < 0.01). The soil carbon stock over the entire study area was mapped using a conditional kriging approach which jointly uses the collected soil carbon data and satellite-based land use images. Based on the kriging map, the spatially soil carbon stock (0-1 m dept) ranged about 2 kg/m(2) in highly developed areas to more than 23 kg/m(2) in intensively cultivated areas as well as the averaged soil carbon stock (0-1 m depth) was estimated as 10.4 kg/m(2). Copyright © 2014 Elsevier Ltd. All rights reserved.

Genome Sequence of Marinobacter sp. Strain MCTG268 Isolated from the Cosmopolitan Marine Diatom Skeletonema costatum

DOE PAGES

Gutierrez, Tony; Whitman, William B.; Huntemann, Marcel; ...

2016-09-08

Marinobactersp. strain MCTG268 was isolated from the cosmopolitan marine diatomSkeletonema costatumand can degrade oil hydrocarbons as sole sources of carbon and energy. Here, we present the genome sequence of this strain, which is 4,449,396 bp with 4,157 genes and an average G+C content of 57.0%.

Genome Sequence of Arenibacter algicola Strain TG409, a Hydrocarbon-Degrading Bacterium Associated with Marine Eukaryotic Phytoplankton

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gutierrez, Tony; Whitman, William B.; Huntemann, Marcel

Arenibacter algicolastrain TG409 was isolated fromSkeletonema costatumand exhibits the ability to utilize polycyclic aromatic hydrocarbons as sole sources of carbon and energy. Here, we present the genome sequence of this strain, which is 5,550,230 bp with 4,722 genes and an average G+C content of 39.7%.

Genome Sequence of Marinobacter sp. Strain MCTG268 Isolated from the Cosmopolitan Marine Diatom Skeletonema costatum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gutierrez, Tony; Whitman, William B.; Huntemann, Marcel

Marinobactersp. strain MCTG268 was isolated from the cosmopolitan marine diatomSkeletonema costatumand can degrade oil hydrocarbons as sole sources of carbon and energy. Here, we present the genome sequence of this strain, which is 4,449,396 bp with 4,157 genes and an average G+C content of 57.0%.

Genome Sequence of Arenibacter algicola Strain TG409, a Hydrocarbon-Degrading Bacterium Associated with Marine Eukaryotic Phytoplankton

DOE PAGES

Gutierrez, Tony; Whitman, William B.; Huntemann, Marcel; ...

2016-08-04

Arenibacter algicolastrain TG409 was isolated fromSkeletonema costatumand exhibits the ability to utilize polycyclic aromatic hydrocarbons as sole sources of carbon and energy. Here, we present the genome sequence of this strain, which is 5,550,230 bp with 4,722 genes and an average G+C content of 39.7%.

Calcium Isotopic Compositions of Forearc Sediments from DSDP Site 144

NASA Astrophysics Data System (ADS)

Zhang, Z.; Zhu, H.; Nan, X.; Li, X.; Huang, F.

2016-12-01

It is important to investigate calcium isotopic compositions of reservoirs of the Earth for better application of Ca isotopes into studies of a variety of geochemical problems. Because Ca isotopic compositions for igneous rocks and carbonates are increasingly reported, this maybe bring new requirements on carefully understanding the isotopic compositions of subducted marine sediments. Marine sediments mainly contains carbonates and clays, controlling the compositions of slab-derived materials which are added to the mantle wedge. Obviously, it could have different elemental and calcium isotopic compositions with marine carbonate. Thus, it could also put biases on calcium isotopic signatures of basalts resulted from recycling oceanic carbonate into the mantle. Here, we report calcium isotopic compositions of 17 sediment samples from Deep Sea Drilling Project (DSDP) site 144 (09°27.23' N, 54°20.52' W) which is located about 400 km north of Surinam on the northern flank of the Demerara Rise with a water depth of 2957 meters. These samples have CaO contents ranging from 14.56 wt.% to 41.46 wt.% with an average of 29.61 ± 18.21 (2SD), δ44/40Ca ranges from 0.19 to 0.58 (relative to SRM915a) with an average of 0.40 ± 0.22 (2SD). These carbonate-rich sediments can be used to represent an endmember with high CaO content and low δ44/40Ca, which could modify chemical composition of the upper mantle and subduction zone lavas if they are recycled to the convective mantle during subduction. The positive linear correlation between CaO and δ44/40Ca in the sediments cannot be explained by a simple mixing between marine carbonate and clay. Instead, δ44/40Ca of these samples roughly increase from the Upper Cretaceous to the Early Oligocene, which might reflect the evolution of calcium isotopic compositions of seawater through time.

Substantial soil organic carbon retention along floodplains of mountain streams

NASA Astrophysics Data System (ADS)

Sutfin, Nicholas A.; Wohl, Ellen

2017-07-01

Small, snowmelt-dominated mountain streams have the potential to store substantial organic carbon in floodplain sediment because of high inputs of particulate organic matter, relatively lower temperatures compared with lowland regions, and potential for increased moisture conditions. This work (i) quantifies mean soil organic carbon (OC) content along 24 study reaches in the Colorado Rocky Mountains using 660 soil samples, (ii) identifies potential controls of OC content based on soil properties and spatial position with respect to the channel, and (iii) and examines soil properties and OC across various floodplain geomorphic features in the study area. Stepwise multiple linear regression (adjusted r2 = 0.48, p < 0.001) indicates that percentage of silt and clay, sample depth, percent sand, distance from the channel, and relative elevation from the channel are significant predictors of OC content in the study area. Principle component analysis indicates limited separation between geomorphic floodplain features based on predictors of OC content. A lack of significant differences among floodplain features suggests that the systematic random sampling employed in this study can capture the variability of OC across floodplains in the study area. Mean floodplain OC (6.3 ± 0.3%) is more variable but on average greater than values in uplands (1.5 ± 0.08% to 2.2 ± 0.14%) of the Colorado Front Range and higher than published values from floodplains in other regions, particularly those of larger rivers.

Effects of Retained Austenite Volume Fraction, Morphology, and Carbon Content on Strength and Ductility of Nanostructured TRIP-assisted Steels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shen, Yongfeng; Qiu, LN; Sun, Xin

2015-06-01

With a suite of multi-modal and multi-scale characterization techniques, the present study unambiguously proves that a substantially-improved combination of ultrahigh strength and good ductility can be achieved by tailoring the volume fraction, morphology, and carbon content of the retained austenite (RA) in a transformation-induced-plasticity (TRIP) steel with the nominal chemical composition of 0.19C-0.30Si-1.76Mn-1.52Al (weight percent, wt.%). After intercritical annealing and bainitic holding, a combination ultimate tensile strength (UTS) of 1,100 MPa and true strain of 50% has been obtained, as a result of the ultrafine RA lamellae, which are alternately arranged in the bainitic ferrite around junction regions of ferritemore » grains. For reference, specimens with a blocky RA, prepared without the bainitic holding, yield a low ductility (35%) and a low UTS (800 MPa). The volume fraction, morphology, and carbon content of RA have been characterized using various techniques, including magnetic probing, scanning electron microscopy (SEM), electron-backscatter-diffraction (EBSD), and transmission electron microscopy (TEM). Interrupted tensile tests, mapped using EBSD in conjunction with the kernel average misorientation (KAM) analysis, reveal that the lamellar RA is the governingmicrostructure component responsible for the higher mechanical stability, compared to the blocky one. By coupling these various techniques, we quantitatively demonstrate that in addition to the RA volume fraction, its morphology and carbon content are equally important in optimizing the strength and ductility of TRIP-assisted steels.« less

Optimization of supercritical carbon dioxide extraction of Piper Betel Linn leaves oil and total phenolic content

NASA Astrophysics Data System (ADS)

Aziz, A. H. A.; Yunus, M. A. C.; Arsad, N. H.; Lee, N. Y.; Idham, Z.; Razak, A. Q. A.

2016-11-01

Supercritical Carbon Dioxide (SC-CO2) Extraction was applied to extract piper betel linn leaves. The piper betel leaves oil was used antioxidant, anti-diabetic, anticancer and antistroke. The aim of this study was to optimize the conditions of pressure, temperature and flowrate for oil yield and total phenolic content. The operational conditions of SC-CO2 studied were pressure (10, 20, 30 MPa), temperature (40, 60, 80 °C) and flowrate carbon dioxide (4, 6, 8 mL/min). The constant parameters were average particle size and extraction regime, 355pm and 3.5 hours respectively. First order polynomial expression was used to express the extracted oil while second order polynomial expression was used to express the total phenolic content and the both results were satisfactory. The best conditions to maximize the total extraction oil yields and total phenolic content were 30 MPa, 80 °C and 4.42 mL/min leading to 7.32% of oil and 29.72 MPa, 67.53 °C and 7.98 mL/min leading to 845.085 mg GAE/g sample. In terms of optimum condition with high extraction yield and high total phenolic content in the extracts, the best operating conditions were 30 MPa, 78 °C and 8 mL/min with 7.05% yield and 791.709 mg gallic acid equivalent (GAE)/g sample. The most dominant condition for extraction of oil yield and phenolic content were pressure and CO2 flowrate. The results show a good fit to the proposed model and the optimal conditions obtained were within the experimental range with the value of R2 was 96.13% for percentage yield and 98.52% for total phenolic content.

The Characteristics of Peats and Co2 Emission Due to Fire in Industrial Plant Forests

NASA Astrophysics Data System (ADS)

Ratnaningsih, Ambar Tri; Rayahu Prasytaningsih, Sri

2017-12-01

Riau Province has a high threat to forest fire in peat soils, especially in industrial forest areas. The impact of fires will produce carbon (CO2) emissions in the atmosphere. The magnitude of carbon losses from the burning of peatlands can be estimated by knowing the characteristics of the fire peat and estimating CO2 emissions produced. The objectives of the study are to find out the characteristics of fire-burning peat, and to estimate carbon storage and CO2 emissions. The location of the research is in the area of industrial forest plantations located in Bengkalis Regency, Riau Province. The method used to measure peat carbon is the method of lost in ignation. The results showed that the research location has a peat depth of 600-800 cm which is considered very deep. The Peat fiber content ranges from 38 to 75, classified as hemic peat. The average bulk density was 0.253 gram cm-3 (0.087-0,896 gram cm-3). The soil ash content is 2.24% and the stored peat carbon stock with 8 meter peat thickness is 10723,69 ton ha-1. Forest fire was predicted to burn peat to a depth of 100 cm and produced CO2 emissions of 6,355,809 tons ha-1.

Isotope Ratio Monitoring Gas Chromatography Mass Spectrometry (IRM-GCMS)

NASA Technical Reports Server (NTRS)

Freeman, K. H.; Ricci, S. A.; Studley, A.; Hayes, J. M.

1989-01-01

On Earth, the C-13 content of organic compounds is depleted by roughly 13 to 23 permil from atmospheric carbon dioxide. This difference is largely due to isotope effects associated with the fixation of inorganic carbon by photosynthetic organisms. If life once existed on Mars, then it is reasonable to expect to observe a similar fractionation. Although the strongly oxidizing conditions on the surface of Mars make preservation of ancient organic material unlikely, carbon-isotope evidence for the existence of life on Mars may still be preserved. Carbon depleted in C-13 could be preserved either in organic compounds within buried sediments, or in carbonate minerals produced by the oxidation of organic material. A technique is introduced for rapid and precise measurement of the C-13 contents of individual organic compounds. A gas chromatograph is coupled to an isotope-ratio mass spectrometer through a combustion interface, enabling on-line isotopic analysis of isolated compounds. The isotope ratios are determined by integration of ion currents over the course of each chromatographic peak. Software incorporates automatic peak determination, corrections for background, and deconvolution of overlapped peaks. Overall performance of the instrument was evaluated by the analysis of a mixture of high purity n-alkanes of know isotopic composition. Isotopic values measured via IRM-GCMS averaged withing 0.55 permil of their conventionally measured values.

Warming reduces carbon losses from grassland exposed to elevated atmospheric carbon dioxide.

PubMed

Pendall, Elise; Heisler-White, Jana L; Williams, David G; Dijkstra, Feike A; Carrillo, Yolima; Morgan, Jack A; Lecain, Daniel R

2013-01-01

The flux of carbon dioxide (CO2) between terrestrial ecosystems and the atmosphere may ameliorate or exacerbate climate change, depending on the relative responses of ecosystem photosynthesis and respiration to warming temperatures, rising atmospheric CO2, and altered precipitation. The combined effect of these global change factors is especially uncertain because of their potential for interactions and indirectly mediated conditions such as soil moisture. Here, we present observations of CO2 fluxes from a multi-factor experiment in semi-arid grassland that suggests a potentially strong climate - carbon cycle feedback under combined elevated [CO2] and warming. Elevated [CO2] alone, and in combination with warming, enhanced ecosystem respiration to a greater extent than photosynthesis, resulting in net C loss over four years. The effect of warming was to reduce respiration especially during years of below-average precipitation, by partially offsetting the effect of elevated [CO2] on soil moisture and C cycling. Carbon losses were explained partly by stimulated decomposition of soil organic matter with elevated [CO2]. The climate - carbon cycle feedback observed in this semiarid grassland was mediated by soil water content, which was reduced by warming and increased by elevated [CO2]. Ecosystem models should incorporate direct and indirect effects of climate change on soil water content in order to accurately predict terrestrial feedbacks and long-term storage of C in soil.

Comparative study of different carbon-supported Fe2O3-Pt catalysts for oxygen reduction reaction.

PubMed

Tellez-Cruz, M M; Padilla-Islas, M A; Pérez-González, M; Solorza-Feria, O

2017-11-01

One of the challenges in electrocatalysis is the adequate dispersion of the catalyst on an appropriate porous support matrix, being up to now the most commonly used the carbon-based supports. To overcome this challenge, carbon supports must first be functionalized to guide the catalyst's nucleation, thereby, improving the dispersion and allowing the use of smaller amount of the catalyst material to achieve a higher electrochemically active surface area. This study present the effect of functionalized Vulcan carbon XC72 (FVC) and functionalized Black Pearl carbon (FBPC) as supports on the catalytic activity of decorated Fe 2 O 3 with Pt. Both carbons were functionalized with HNO 3 and subsequently treated with ethanolamine. Fe 2 O 3 nanoparticles were synthesized by chemical reduction and decorated with platinum by epitaxial growth. Pt and Fe 2 O 3 structural phases were identified by XRD and XPS; the Pt content was measured by XPS, and results showed to a high Pt content in Fe 2 O 3 -Pt/FBPC. TEM micrographs reveal nanoparticles with an average size of 2 nm in both supported catalysts. The Fe 2 O 3 -Pt/FVC catalyst presents the highest specific activity and mass activity, 0.21 mA cm -2 Pt and 140 mA mg Pt -1 , respectively, associated to the appropriate distribution of platinum on the Fe 2 O 3 nanoparticles.

Increasing Carbon Loss from Snow-Scoured Alpine Tundra in the Colorado Rocky Mountains: An Indicator of Climate Change?

NASA Astrophysics Data System (ADS)

Knowles, J. F.; Blanken, P.; Williams, M. W.; Lawrence, C. R.

2015-12-01

We used the eddy covariance method to continuously measure the net ecosystem exchange of carbon dioxide for seven years from a snow-scoured alpine tundra meadow on Niwot Ridge in Colorado, USA that may be underlain by sporadic permafrost. On average, the alpine tundra was a net annual source of 232 g C m-2 to the atmosphere, and the source strength of this ecosystem increased over the length of the seven year period due to both reduced carbon uptake during the growing season and increased respiration throughout the winter. To constrain the contribution of permafrost degradation to observed carbon emissions, we also measured the radiocarbon content of actively cycling, occluded, and mineral soil carbon pools across a meso-scale soil moisture and (possible) permafrost gradient within this meadow, as well as the seasonal radiocarbon content of soil respiration. These data suggest that wintertime soil respiration is limited to patches of wet meadow tundra that may be associated with permafrost. Furthermore, soil respiration from one of these locations indicates preferential turnover of a relatively slow cycling carbon pool during the winter. Given that summer air temperatures and positive degree days have been increasing on Niwot Ridge since the middle of the 20th century, this research suggests that an alpine tundra permafrost-respiration feedback to climate change, similar to that observed in arctic tundra ecosystems, may be currently underway.

Warming Reduces Carbon Losses from Grassland Exposed to Elevated Atmospheric Carbon Dioxide

PubMed Central

Pendall, Elise; Heisler-White, Jana L.; Williams, David G.; Dijkstra, Feike A.; Carrillo, Yolima; Morgan, Jack A.; LeCain, Daniel R.

2013-01-01

The flux of carbon dioxide (CO2) between terrestrial ecosystems and the atmosphere may ameliorate or exacerbate climate change, depending on the relative responses of ecosystem photosynthesis and respiration to warming temperatures, rising atmospheric CO2, and altered precipitation. The combined effect of these global change factors is especially uncertain because of their potential for interactions and indirectly mediated conditions such as soil moisture. Here, we present observations of CO2 fluxes from a multi-factor experiment in semi-arid grassland that suggests a potentially strong climate – carbon cycle feedback under combined elevated [CO2] and warming. Elevated [CO2] alone, and in combination with warming, enhanced ecosystem respiration to a greater extent than photosynthesis, resulting in net C loss over four years. The effect of warming was to reduce respiration especially during years of below-average precipitation, by partially offsetting the effect of elevated [CO2] on soil moisture and C cycling. Carbon losses were explained partly by stimulated decomposition of soil organic matter with elevated [CO2]. The climate – carbon cycle feedback observed in this semiarid grassland was mediated by soil water content, which was reduced by warming and increased by elevated [CO2]. Ecosystem models should incorporate direct and indirect effects of climate change on soil water content in order to accurately predict terrestrial feedbacks and long-term storage of C in soil. PMID:23977180

Combustion characteristics of paper and sewage sludge in a pilot-scale fluidized bed.

PubMed

Yu, Yong-Ho; Chung, Jinwook

2015-01-01

This study characterizes the combustion of paper and sewage sludge in a pilot-scale fluidized bed. The highest temperature during combustion within the system was found at the surface of the fluidized bed. Paper sludge containing roughly 59.8% water was burned without auxiliary fuel, but auxiliary fuel was required to incinerate the sewage sludge, which contained about 79.3% water. The stability of operation was monitored based on the average pressure and the standard deviation of pressure fluctuations. The average pressure at the surface of the fluidized bed decreased as the sludge feed rate increased. However, the standard deviation of pressure fluctuations increased as the sludge feed rate increased. Finally, carbon monoxide (CO) emissions decreased as oxygen content increased in the flue gas, and nitrogen oxide (NOx) emissions were also tied with oxygen content.

Aerosol chemistry and the effect of aerosol water content on visibility impairment and radiative forcing in Guangzhou during the 2006 Pearl River Delta campaign.

PubMed

Jung, Jinsang; Lee, Hanlim; Kim, Young J; Liu, Xingang; Zhang, Yuanhang; Gu, Jianwei; Fan, Shaojia

2009-08-01

Optical and chemical aerosol measurements were obtained from 2 to 31 July 2006 at an urban site in the metropolitan area of Guangzhou (China) as part of the Program of Regional Integrated Experiment of Air Quality over Pearl River Delta (PRIDE-PRD2006) to investigate aerosol chemistry and the effect of aerosol water content on visibility impairment and radiative forcing. During the PRIDE-PRD2006 campaign, the average contributions of ammonium sulfate, organic mass by carbon (OMC), elemental carbon (EC), and sea salt (SS) to total PM(2.5) mass were measured to be 36.5%, 5.7%, 27.1%, 7.8%, and 3.7%, respectively. Compared with the clean marine period, (NH(4))(2)SO(4), NH(4)NO(3), and OMC were all greatly enhanced (by up to 430%) during local haze periods via the accumulation of a secondary aerosol component. The OMC dominance increased when high levels of biomass burning influenced the measurement site while (NH(4))(2)SO(4) and OMC did when both biomass burning and industrial emissions influenced it. The effect of aerosol water content on the total light-extinction coefficient was estimated to be 34.2%, of which 25.8% was due to aerosol water in (NH(4))(2)SO(4), 5.1% that in NH(4)NO(3), and 3.3% that in SS. The average mass-scattering efficiency (MSE) of PM(10) particles was determined to be 2.2+/-0.6 and 4.6+/-1.7m(2)g(-1) under dry (RH<40%) and ambient conditions, respectively. The average single-scattering albedo (SSA) was 0.80+/-0.08 and 0.90+/-0.04 under dry and ambient conditions, respectively. Not only are the extinction and scattering coefficients greatly enhanced by aerosol water content, but MSE and SSA are also highly sensitive. It can be concluded that sulfate and carbonaceous aerosol, as well as aerosol water content, play important roles in the processes that determine visibility impairment and radiative forcing in the ambient atmosphere of the Guangzhou urban area.

Isotopic Clues on Factors Controlling Geochemical Fluxes From Large Watersheds in Eastern Canada

NASA Astrophysics Data System (ADS)

Rosa, E.; Helie, J.; Ghaleb, B.; Hillaire-Marcel, C.; Gaillardet, J.

2008-12-01

A monitoring and monthly sampling program of the Nelson, Ottawa, St. Lawrence, La Grande and Great Whale rivers was started in September 2007. It provides information on the seasonality and sources of geochemical fluxes into the Hudson Bay and the North Atlantic from watersheds covering more than 2.6 106 km2 of the eastern Canadian boreal domain. Measurements of pH and alkalinity, analyses of major ions, strontium and dissolved silica, 2H and 18O of water, concentrations and isotopic properties of dissolved organic and inorganic carbon (13C) and uranium (234U/238U) were performed. Lithology more than latitudinal climatic gradients controls the river geochemistry. Rivers draining silicate terrains show lower dissolved U concentrations but greater 234U/238U disequilibria than rivers draining carbonates (average of 1.38 vs. 1.23). Groundwater supplies might exert some control on these U- isotope signatures. No clear seasonality is observed in 234U/238U ratios, but U concentrations are correlated to dissolved organic carbon (DOC) concentrations in most rivers. Rivers draining carbonates present higher total dissolved carbon concentrations and higher 13C-contents in dissolved inorganic carbon (DIC), in response to the dissolution of soil carbonates. DOC/DIC ratios above 2.4 are observed in rivers draining silicates; their lower 13C-DIC content directly reflects the organic matter oxidation in soils. Total dissolved solids are one order of magnitude or more greater in rivers draining carbonates, showing the strong difference in chemical weathering rates according to the geological setting. The stability in chemical fluxes and water isotopic compositions in the La Grande River, which hosts hydroelectric reservoirs covering more than 12 000 km2, indicates that it is the most buffered hydrological system among the investigated watersheds. Seasonal fluctuations are observed elsewhere, with maximum geochemical fluxes during the spring snowmelt. 2H-18O content of river water appears to be the only parameter presenting a strong latitudinal and climatic gradient (independent of lithology).

[Effects of adding straw carbon source to root knot nematode diseased soil on soil microbial biomass and protozoa abundance].

PubMed

Zhang, Si-Hui; Lian, Jian-Hong; Cao, Zhi-Ping; Zhao, Li

2013-06-01

A field experiment with successive planting of tomato was conducted to study the effects of adding different amounts of winter wheat straw (2.08 g x kg(-1), 1N; 4.16 g x kg(-1), 2N; and 8.32 g x kg(-1), 4N) to the soil seriously suffered from root knot nematode disease on the soil microbial biomass and protozoa abundance. Adding straw carbon source had significant effects on the contents of soil microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) and the abundance of soil protozoa, which all decreased in the order of 4N > 2N > 1N > CK. The community structure of soil protozoa also changed significantly under straw addition. In the treatments with straw addition, the average proportion of fagellate, amoeba, and ciliates accounted for 36.0%, 59.5%, and 4.5% of the total protozoa, respectively. Under the same adding amounts of wheat straw, there was an increase in the soil MBC and MBN contents, MBC/MBN ratio, and protozoa abundance with increasing cultivation period.

Levels and speciation of heavy metals in soils of industrial Southern Nigeria.

PubMed

Olajire, A A; Ayodele, E T; Oyedirdan, G O; Oluyemi, E A

2003-06-01

A knowledge of the total content of trace metals is not enough to fully assess the environmental impact of polluted soils. For this reason, the determination of metal species in solution is important to evaluate their behaviour in the environment and their mobilization capacity. Sequential extraction procedure was used to speciate five heavy metals (Cd, Pb, Cu, Ni and Zn) from four contaminated soils of Southern Nigeria into six operationally defined geochemical species: water soluble, enchangeable, carbonates, Fe-Mn oxide, organic and residual. Metal recoveries were within +/- 10% of the independently determined total Cd, Pb, Cu, Ni and Zn concentrations. The highest amount of Cd (avg. 30%) in the nonresidual fractions was found in the exchangeable fraction, while Cu and Zn were significantly associated with the organic fraction. The carbonate fraction contained on average 14, 18.6, 12.6, 13 and 11% and the residual fraction contained on average 47, 18, 33, 50 and 25% of Cd, Pb, Cu, Ni and Zn respectively. Assuming that mobility and bioavailability of these metals are related to the solubility of the geochemical form of the metals, and that they decrease in the order of extraction sequence, the apparent mobility and potential bioavailability for these five metals in the soil were: Pb > Zn > Cu > Ni > Cd. The mobility indexes of copper and nickel correlated positively and significantly with the total content of metals, while mobility indexes of cadmium and zinc correlated negatively and significantly with the total content of metals.

Filter-based measurement of light absorption by brown carbon in PM2.5 in a megacity in South China.

PubMed

Li, Sheng; Zhu, Ming; Yang, Weiqiang; Tang, Mingjin; Huang, Xueliang; Yu, Yuegang; Fang, Hua; Yu, Xu; Yu, Qingqing; Fu, Xiaoxin; Song, Wei; Zhang, Yanli; Bi, Xinhui; Wang, Xinming

2018-08-15

Carbonaceous aerosols represent an important nexus between air pollution and climate change. Here we collected filter-based PM 2.5 samples during summer and autumn in 2015 at one urban and two rural sites in Guangzhou, a megacity in southern China, and got the light absorption by black carbon (BC) and brown carbon (BrC) resolved with a DRI Model 2015 multi-wavelength thermal/optical carbon analyzer apart from determining the organic carbon (OC) and elemental carbon (EC) contents. On average BrC contributed 12-15% of the measured absorption at 405nm (LA 405 ) during summer and 15-19% during autumn with significant increase in the LA 405 by BrC at the rural sites. Carbonaceous aerosols, identified as total carbon (TC), yielded average mass absorption efficiency at 405nm (MAE 405 ) that were approximately 45% higher in autumn than in summer, an 83% increase was noted in the average MAE 405 for OC, compared with an increase of only 14% in the average MAE 405 for EC. The LA 405 by BrC showed a good correlation (p<0.001) with the ratios of secondary OC to PM 2.5 in summer. However, this correlation was poor (p>0.1) in autumn, implying greater secondary formation of BrC in summer. The correlations between levoglucosan (a marker of biomass burning) and the LA 405 by BrC were significant during autumn but insignificant during summer, suggesting that the observed increase in the LA 405 by BrC during autumn in rural areas was largely related to biomass burning. The measurements of light absorption at 550nm presented in this study indicated that the use of the IMPROVE algorithm with an MAE value of 10m 2 /g for EC to approximate light absorption may be appropriate in areas not strongly affected by fossil fuel combustion; however, this practice would underestimate the absorption of light by PM 2.5 in areas heavily affected by vehicle exhausts and coal burning. Copyright © 2018 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lincoln, D.E.

Assay procedures for analysis of four groups of allelochemicals in Artemisia tridentata, big sagebrush, were established. Growth of Artemisia under high and low light at three CO/sub 2/ levels demonstrated that this species also undegoes a ''dilution'' of the leaf nitrogen content and is useful as test species for herbivory response to CO/sub 2/ induced effects. The initiial experiment also showed that high irradiance is a necessary growth condition. Plants from a single population of A. Tridentata were grown at the Duke Phytotron in three CO/sub 2/ regimed and fed to two species of grasshoppers. Sagabrush plants grew more andmore » had lower leaf nitrogen contents as CO/sub 2/ concentration increased. However, the plants had on average lowere leaf carbon as well as lower leaf niitrogen contents with elevated CO/sub 2/. The source of the lower leaf nutritional value does not appear to be solely an increase in carbon content. Grasshopper consumption was greater on leaves from elevated future and from reduced historical CO/sub 2/ regimes, compared to the current concentration. The increased consumption of leaves from elevated CO/sub 2/ is in agreement with previous results. Grasshopper consumption was significantly related to leaf allelochemical content, but not to leaf nitrogen content. The consumption difference among CO/sub 2/ regimes appeared to result from allelochemical differences, which in turn may result from genetic variation or from CO/sub 2/ treatments. 17 refs., 2 figs., 4 tabs.« less

Association of polychlorinated biphenyls (PCBs) with live algae and total lipids in rivers - A field-based approach

USGS Publications Warehouse

Fitzgerald, S.A.; Steuer, J.J.

2006-01-01

The association of PCBs and live algal cells in rivers was studied at four locations during four seasons in two Wisconsin rivers. Positive relations between particle-associated PCBs and both chlorophyll-a and algal carbon concentrations indicated that live algal cells were a significant sorption phase for dissolved PCBs. Large Pennate diatoms (Navicula, Synedra, Pinnularia, Diatoma, and Cocconeis), or more rarely, Euglenoids (Trachelomonas sp.), dominated most sample assemblages on an algal carbon basis. These assemblages made up the highest percentage of total SOC during spring (average=50%) and lowest during summer (average=15%). At the three impounded sites, most individual PCB congeners were relatively enriched in samples characterized by: (1) high concentrations of algal carbon (as a percent of SOC), (2) algal assemblages dominated (or co-dominated) by Euglenoids, and (3) high concentrations of total lipids. Despite relatively higher masses of sorbed PCBs in the most lipid-rich samples, there was no robust correlation between total lipid content and particle-associated PCBs when aggregating all samples from the study. A possible explanation is that PCBs are associated with other structural components in live algae and (or) departure from chemical equilibrium in the river due to algal growth kinetics. A kinetic uptake model was used to calculate the mass of PCBs associated with the total organic carbon content of live algae. Based on this model, PCBs were enriched in algal cells during bloom seasons (spring and fall) compared to non-bloom seasons (summer and winter). Further, although individual PCB congener partition coefficients (log) to live algal cells (range=5.3-6.4) overlapped to those for detritus (range=3.6-7.4), PCBs tended to be enriched in detrital carbon pools during non-bloom conditions. The larger range of estimated PCB partition coefficients for detritus likely reflects the more heterogeneous nature of this material compared to live algal cells.

Prediction of soil organic carbon in a coal mining area by Vis-NIR spectroscopy.

PubMed

Sun, Wenjuan; Li, Xinju; Niu, Beibei

2018-01-01

Coal mining has led to increasingly serious land subsidence, and the reclamation of the subsided land has become a hot topic of concern for governments and scholars. Soil quality of reclaimed land is the key indicator to the evaluation of the reclamation effect; hence, rapid monitoring and evaluation of reclaimed land is of great significance. Visible-near infrared (Vis-NIR) spectroscopy has been shown to be a rapid, timely and efficient tool for the prediction of soil organic carbon (SOC). In this study, 104 soil samples were collected from the Baodian mining area of Shandong province. Vis-NIR reflectance spectra and soil organic carbon content were then measured under laboratory conditions. The spectral data were first denoised using the Savitzky-Golay (SG) convolution smoothing method or the multiple scattering correction (MSC) method, after which the spectral reflectance (R) was subjected to reciprocal, reciprocal logarithm and differential transformations to improve spectral sensitivity. Finally, regression models for estimating the SOC content by the spectral data were constructed using partial least squares regression (PLSR). The results showed that: (1) The SOC content in the mining area was generally low (at the below-average level) and exhibited great variability. (2) The spectral reflectance increased with the decrease of soil organic carbon content. In addition, the sensitivity of the spectrum to the change in SOC content, especially that in the near-infrared band of the original reflectance, decreased when the SOC content was low. (3) The modeling results performed best when the spectral reflectance was preprocessed by Savitzky-Golay (SG) smoothing coupled with multiple scattering correction (MSC) and first-order differential transformation (modeling R2 = 0.86, RMSE = 2.00 g/kg, verification R2 = 0.78, RMSE = 1.81 g/kg, and RPD = 2.69). In addition, the first-order differential of R combined with SG, MSC with R, SG together with MSC and R also produced better modeling results than other pretreatment combinations. Vis-NIR modeling with specific spectral preprocessing methods could predict SOC content effectively.

Survey of mercury, cadmium and lead content of household batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Recknagel, Sebastian, E-mail: sebastian.recknagel@bam.de; Radant, Hendrik; Kohlmeyer, Regina

2014-01-15

Highlights: • A well selected sample of 146 batteries was analysed for its heavy metals content. • A comparison was made between heavy metals contents in batteries in 2006 and 2011. • No significant change after implementation of the new EU Batteries Directive. • Severe differences in heavy metal contents were found in different battery-types. - Abstract: The objective of this work was to provide updated information on the development of the potential impact of heavy metal containing batteries on municipal waste and battery recycling processes following transposition of the new EU Batteries Directive 2006/66/EC. A representative sample of 146more » different types of commercially available dry and button cells as well as lithium-ion accumulators for mobile phones were analysed for their mercury (Hg)-, cadmium (Cd)- and lead (Pb)-contents. The methods used for preparing the cells and analysing the heavy metals Hg, Cd, and Pb were either developed during a former study or newly developed. Several batteries contained higher mass fractions of mercury or cadmium than the EU limits. Only half of the batteries with mercury and/or lead fractions above the marking thresholds were labelled. Alkaline–manganese mono-cells and Li-ion accumulators, on average, contained the lowest heavy metal concentrations, while zinc–carbon batteries, on average, contained the highest levels.« less

Particulate barium tracing of significant mesopelagic carbon remineralisation in the North Atlantic

NASA Astrophysics Data System (ADS)

Lemaitre, Nolwenn; Planquette, Hélène; Planchon, Frédéric; Sarthou, Géraldine; Jacquet, Stéphanie; García-Ibáñez, Maribel I.; Gourain, Arthur; Cheize, Marie; Monin, Laurence; André, Luc; Laha, Priya; Terryn, Herman; Dehairs, Frank

2018-04-01

The remineralisation of sinking particles by prokaryotic heterotrophic activity is important for controlling oceanic carbon sequestration. Here, we report mesopelagic particulate organic carbon (POC) remineralisation fluxes in the North Atlantic along the GEOTRACES-GA01 section (GEOVIDE cruise; May-June 2014) using the particulate biogenic barium (excess barium; Baxs) proxy. Important mesopelagic (100-1000 m) Baxs differences were observed along the transect depending on the intensity of past blooms, the phytoplankton community structure, and the physical forcing, including downwelling. The subpolar province was characterized by the highest mesopelagic Baxs content (up to 727 pmol L-1), which was attributed to an intense bloom averaging 6 mg chl a m-3 between January and June 2014 and by an intense 1500 m deep convection in the central Labrador Sea during the winter preceding the sampling. This downwelling could have promoted a deepening of the prokaryotic heterotrophic activity, increasing the Baxs content. In comparison, the temperate province, characterized by the lowest Baxs content (391 pmol L-1), was sampled during the bloom period and phytoplankton appear to be dominated by small and calcifying species, such as coccolithophorids. The Baxs content, related to oxygen consumption, was converted into a remineralisation flux using an updated relationship, proposed for the first time in the North Atlantic. The estimated fluxes were of the same order of magnitude as other fluxes obtained using independent methods (moored sediment traps, incubations) in the North Atlantic. Interestingly, in the subpolar and subtropical provinces, mesopelagic POC remineralisation fluxes (up to 13 and 4.6 mmol C m-2 d-1, respectively) were equalling and occasionally even exceeding upper-ocean POC export fluxes, deduced using the 234Th method. These results highlight the important impact of the mesopelagic remineralisation on the biological carbon pump of the studied area with a near-zero, deep (> 1000 m) carbon sequestration efficiency in spring 2014.

Terrestrial and marine trophic pathways support young-of-year growth in a nearshore Arctic fish

USGS Publications Warehouse

von Biela, Vanessa R.; Zimmerman, Christian E.; Cohn, Brian R.; Welker, Jeffrey M.

2013-01-01

River discharge supplies nearshore communities with a terrestrial carbon source that is often reflected in invertebrate and fish consumers. Recent studies in the Beaufort Sea have documented widespread terrestrial carbon use among invertebrates, but only limited use among nearshore fish consumers. Here, we examine the carbon source and diet of rapidly growing young-of-year Arctic cisco (Coregonus autumnalis) using stable isotope values (δ13C and δ15N) from muscle and diet analysis (stomach contents) during a critical and previously unsampled life stage. Stable isotope values (δ15N and δ13C) may differentiate between terrestrial and marine sources and integrate over longer time frames (weeks). Diet analysis provides species-specific information, but only from recent foraging (days). Average δ13C for all individuals was −25.7 ‰, with the smallest individuals possessing significantly depleted δ13C values indicative of a stronger reliance of terrestrial carbon sources as compared to larger individuals. Average δ15N for all individuals was 10.4 ‰, with little variation among individuals. As fish length increased, the proportion of offshore Calanus prey and neritic Mysis prey increased. Rapid young-of-year growth in Arctic cisco appears to use terrestrial carbon sources obtained by consuming a mixture of neritic and offshore zooplankton. Shifts in the magnitude or phenology of river discharge and the delivery of terrestrial carbon may alter the ecology of nearshore fish consumers.

BOREAS TGB-12 Rn-222 Flux Data over the NSA

NASA Technical Reports Server (NTRS)

Hall, Forrest G. (Editor); Conrad, Sara K.; Trumbore, Susan; Sundquist, Eric; Winston, Greg

2000-01-01

The BOREAS TGB-12 team made measurements of soil carbon inventories, carbon concentration in soil gases, and rates of soil respiration at several sites to estimate the rates of carbon accumulation and turnover in each of the major vegetation types. Sampling strategies for soils were designed to take advantage of local fire chronosequences, so that the accumulation of carbon in new moss growth could be determined. All the data are used to 1) calculate the inventory of carbon and nitrogen in moss and mineral soil layers at NSA sites, 2) determine the rates of input and turnover (using both accumulation since the last stand-killing fire and radiocarbon data), and 3) link changes in soil respiration rate to shifts in the C-14 content of soil CO2 to determine the average "age" respired CO2. These Rn-222 flux data were collected from 15-Nov-1993 to 16-Aug-1994 over the NSA sites. The data in this data set are stored in tabular ASCII files.

Sedimentological and Stable Isotope Changes at the Messinian-Pliocene Boundary Along a West to East Mediterranean Transect.

NASA Astrophysics Data System (ADS)

Pierre, C.; Rouchy, J.; Blanc-Valleron, M.

2001-12-01

During Messinian times, the whole Mediterranean area was submitted to evaporitic conditions which ended by the "Lago-Mare" brackish episode before the reset of open marine conditions in the early Pliocene. These major paleoceanographic changes resulted from regional tectonic reorganizations and global climate changes at this critical time interval, both acting to modify drastically the physiography and the hydrological budget of the Mediterranean basins. There exist outcropping sections and a few deep-sea ODP cores which contain the complete and continuous sedimentary sequence of the Messinian-Pliocene boundary (MPB), making it possible to follow the paleoenvironmental changes at a high resolution scale. We compare here sedimentological and carbonate stable isotope records on three sections for which a high- resolution sampling was applied to the 2 meters thick interval including the MPB. In the Vera section from South Spain, there is no clear change in the carbonate content of the silty clay succession when crossing the MPB. The oxygen and carbon isotopic compositions of calcite both increase by 1 permil across a 40 cm-thick interval which corresponds to the Messinian-Pliocene transition. At ODP Site 968 from the eastern Levantine basin, there is an important sedimentary change between Messinian brown silty clays containing about 20 percent of carbonate and Pliocene gray nannofossil ooze which carbonate content averages 60 percent. Across this 10 cm-thick transitional interval, the oxygen and carbon isotopic compositions of bulk calcite both increase by 4.5 permil. In the Pissouri section from Cyprus, the uppermost Messinian reddish to brown marls with paleosoils are overlain by white Pliocene marls. The carbonate content increases from 20 percent to reach 60 percent across a 40 cm-thick transitional interval. Within this interval corresponding to the MPB, the oxygen and carbon isotopic compositions increase by 4 permil and 2 permil respectively. These results indicate that the MPB is recorded everywhere from W to E Mediterranean by significant and sharp increases in the oxygen and carbon isotopic compositions, which indicate that the early Pliocene marine flooding of the Mediterranean basins was a very abrupt event.

Influence of test fuel properties and composition on UNECE R101 CO2 and fuel economy valuation

NASA Astrophysics Data System (ADS)

Parker, A.

2015-12-01

CO2 emission and fuel consumption of passenger cars is now assessed by using a simplistic procedure measuring the emission during a test performed without any control of the fuel properties and computing the fuel consumption through an unsophisticated formula. As pump gasoline and diesel fuels are refinery products mixture of many different hydrocarbons, and in case of gasoline may also contain a significant amount of oxygenates, the fuel properties, including the density, carbon and energy content may strongly vary from one pump fuel to the other. Being the specific test fuels carefully selected by the car manufacturers and everything but randomly chosen pump fuels, the claimed CO2 emission and fuel economy figures may differ largely from the certification values. I show from the analysis of the 2014 UK government data for 2358 diesel and 2103 petrol vehicles how same volumes of only theoretically same pump fuels used during the certification test by the cars manufacturers unfortunately do not produce the same carbon dioxide emission, and very likely do not have the same energy content. The CO2 emission per liter of diesel fuel is shown to oscillate froma maximum of 3049 g to a minimum of 2125 g, with an average of 2625 g, froma +16.13% to a -19.06% of the average. TheCO2 emission per liter of petrol fuel is shown to oscillate even more from a maximum of 3735 g to a minimum of 1767 g with an average of 2327 g, from a +60.48% to a -24.05% of the average. The proposed solution is to center the assessment on the energy demand by measuring with accuracy the mass of fuel consumed and the fuel properties of the test fuel starting from the lower heating. The corrected fuel consumption and the corrected carbon dioxide emission to mention from the test are then computed by using pure hydrocarbon reference fuels for diesel and petrol having a given lower heating value and a given hydrocarbon composition. Alternatively, exactly the same test fuel should be used by all the manufacturers.

Nitrogen and carbon isotopic dynamics of subarctic soils and plants in southern Yukon Territory and its implications for paleoecological and paleodietary studies.

PubMed

Tahmasebi, Farnoush; Longstaffe, Fred J; Zazula, Grant; Bennett, Bruce

2017-01-01

We examine here the carbon and nitrogen isotopic compositions of bulk soils (8 topsoil and 7 subsoils, including two soil profiles) and five different plant parts of 79 C3 plants from two main functional groups: herbs and shrubs/subshrubs, from 18 different locations in grasslands of southern Yukon Territory, Canada (eastern shoreline of Kluane Lake and Whitehorse area). The Kluane Lake region in particular has been identified previously as an analogue for Late Pleistocene eastern Beringia. All topsoils have higher average total nitrogen δ15N and organic carbon δ13C than plants from the same sites with a positive shift occurring with depth in two soil profiles analyzed. All plants analyzed have an average whole plant δ13C of -27.5 ± 1.2 ‰ and foliar δ13C of -28.0 ± 1.3 ‰, and average whole plant δ15N of -0.3 ± 2.2 ‰ and foliar δ15N of -0.6 ± 2.7 ‰. Plants analyzed here showed relatively smaller variability in δ13C than δ15N. Their average δ13C after suitable corrections for the Suess effect should be suitable as baseline for interpreting diets of Late Pleistocene herbivores that lived in eastern Beringia. Water availability, nitrogen availability, spacial differences and intra-plant variability are important controls on δ15N of herbaceous plants in the study area. The wider range of δ15N, the more numerous factors that affect nitrogen isotopic composition and their likely differences in the past, however, limit use of the modern N isotopic baseline for vegetation in paleodietary models for such ecosystems. That said, the positive correlation between foliar δ15N and N content shown for the modern plants could support use of plant δ15N as an index for plant N content and therefore forage quality. The modern N isotopic baseline cannot be applied directly to the past, but it is prerequisite to future efforts to detect shifts in N cycling and forage quality since the Late Pleistocene through comparison with fossil plants from the same region.

Vehicle emissions and consumer information in car advertisements.

PubMed

Wilson, Nick; Maher, Anthony; Thomson, George; Keall, Michael

2008-04-29

The advertising of vehicles has been studied from a safety perspective but not in terms of vehicle air pollutants. We aimed to examine the content and trends of greenhouse gas emissions and air pollution-related information, in light passenger vehicle advertisements. Content analysis of the two most popular current affairs magazines in New Zealand for the five year period 2001-2005 was undertaken (n = 514 advertisements). This was supplemented with vehicle data from official websites. The advertisements studied provided some information on fuel type (52%), and engine size (39%); but hardly any provided information on fuel efficiency (3%), or emissions (4%). Over the five-year period the reported engine size increased significantly, while fuel efficiency did not improve. For the vehicles advertised, for which relevant official website data could be obtained, the average "greenhouse rating" for carbon dioxide (CO2) emissions was 5.1, with a range from 0.5 to 8.5 (on a scale with 10 being the best and 0.5 being the most polluting). The average CO2 emissions were 50% higher than the average for cars made by European manufacturers. The average "air pollution" rating for the advertised vehicles was 5.4 (on the same 1-10 scale). The yearly averages for the "greenhouse" or "air pollution" ratings did not change significantly over the five-year period. One advertised hybrid vehicle had a fuel consumption that was under half the average (4.4 versus 9.9 L/100 km), as well as the best "greenhouse" and "air pollution" ratings. To enhance informed consumer choice and to control greenhouse gas and air pollution emissions, governments should introduce regulations on the content of vehicle advertisements and marketing (as started by the European Union). Similar regulations are already in place for the marketing of many other consumer products.

The effect of ocean alkalinity and carbon transfer on deep-sea carbonate ion concentration during the past five glacial cycles

NASA Astrophysics Data System (ADS)

Kerr, Joanna; Rickaby, Rosalind; Yu, Jimin; Elderfield, Henry; Sadekov, Aleksey Yu.

2017-08-01

Glacial-interglacial deep Indo-Pacific carbonate ion concentration ([CO32-]) changes were mainly driven by two mechanisms that operated on different timescales: 1) a long-term increase during glaciation caused by a carbonate deposition reduction on shelves (i.e., the coral reef hypothesis), and 2) transient carbonate compensation responses to deep ocean carbon storage changes. To investigate these mechanisms, we have used benthic foraminiferal B/Ca to reconstruct deep-water [CO32-] in cores from the deep Indian and Equatorial Pacific Oceans during the past five glacial cycles. Based on our reconstructions, we suggest that the shelf-to-basin shift of carbonate deposition raised deep-water [CO32-], on average, by 7.3 ± 0.5 (SE) μmol/kg during glaciations. Oceanic carbon reorganisations during major climatic transitions caused deep-water [CO32-] deviations away from the long-term trend, and carbonate compensation processes subsequently acted to restore the ocean carbonate system to new steady state conditions. Deep-water [CO32-] showed similar patterns to sediment carbonate content (%CaCO3) records on glacial-interglacial timescales, suggesting that past seafloor %CaCO3 variations were dominated by deep-water carbonate preservation changes at our studied sites.

The effect of sewage sludge application on soil properties and willow (Salix sp.) cultivation.

PubMed

Urbaniak, Magdalena; Wyrwicka, Anna; Tołoczko, Wojciech; Serwecińska, Liliana; Zieliński, Marek

2017-05-15

The aim of the study was to determine the impact of sewage sludge from three wastewater treatment plants of different sizes (small, medium and large) applied in two doses (3 and 9 tons per hectare) on soil properties, determined as the content of organic carbon and humus fractions, bacterial abundance, phytotoxicity and PCDD/PCDF TEQ concentrations. The study also evaluated the impact of this sewage sludge on the biometric and physiological parameters and detoxification reaction of willow (Salix sp.) as a typical crop used for the remediation of soil following sludge application. The cultivation of willow on soil treated with sludge was found to result in a gradual increase of humus fractions, total organic carbon content and bacterial abundance as well as soil properties measured using Lepidium sativum. However, it also produced an initial increase of soil phytotoxicity, indicated by Sinapis alba and Sorghum sacharatum, and PCDD/PCDF Toxic Equivalent (TEQ) concentrations, which then fell during the course of the experiment, particularly in areas planted by willow. Although the soil phytotoxicity and PCDD/PCDF TEQ content of the sewage sludge-amended soil initially increased, sludge application was found to have a positive influence on willow, probably due to its high nutrient and carbon content. The obtained results reveal increases in willow biomass, average leaf surface area and leaf length as well as chlorophyll a+b content. Moreover, a strong decline was found in the activity of the detoxifying enzyme glutathione S-transferase (GSTs), a multifunctional enzyme involved in the metabolism of xenobiotics in plants, again demonstrating the used sludge had a positive influence on willow performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Carbon, nitrogen, and phosphorus transport by world rivers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meybeck, M.

1982-04-01

The various forms (dissolved and particulate, organic and inorganic) of carbon, nitrogen, and phosphorus in world rivers are reviewed from literature data. Natural levels are based mainly on major rivers for the subarctic and tropical zones which are still unpolluted and on smaller streams for the temperate zone. Atmospheric fallout is also reviewed. Natural contents of dissolved organic carbon (DOC) are mainly dependent on environmental conditions: DOC varies from 1 mg 1/sup -1/ in the mountainous alpine environments to 20 mg 1/sup -1/ in some taiga rivers. The world DOC average is 5.75 mg l/sup -1/. Nitrogen forms include dissolvedmore » organic nitrogen (DON), dissolved inorganic nitrogen (DIN = N - NH/sub 4//sup +/ + N - NO/sub 3//sup -/ + N - NO/sub 2//sup -/), and particulate organic nitrogen (PON). Natural levels are very low: DIN = 120 ..mu..g 1/sup -1/ of which only 15 percent is present as ammonia, and 1 percent as nitrite. Phosphorus is naturally present in very low amounts: around 10 ..mu..g 1/sup -1/ for P-PO/sub 4//sup 3/ and 25 ..mu..g 1/sup -1/ for total dissolved phosphorus (TDP which includes the organic form). The average nutrient content of rains has been estimated with a set of unpolluted stations: P - PO/sub 4/ = 5 ..mu..g 1/sup -1/, TDP = 10, N - NO/sub 2/ = 5, N - NH/sub 4/ = 225, DON = 225, and N - NO/sub 3/ = 175 ..mu..g 1/sup -1/. TOC levels are probably around several mg 1/sup -1/. These contents are very similar to those found in unpolluted rivers. Man's influence on surface waters has now greatly increased natural nutrient levels. Total dissolved P and N have globally increased by a factor of two and locally (Western Europe, North America) by factors of 10 to 50. These increases were found to be directly proportional to the watershed population and to its energy consumption.« less

Seasonal variability of carbonaceous aerosols in an urban background area in Southern Italy

NASA Astrophysics Data System (ADS)

Cesari, D.; Merico, E.; Dinoi, A.; Marinoni, A.; Bonasoni, P.; Contini, D.

2018-02-01

Organic (OC) and Elemental Carbon (EC) are important components of atmospheric aerosol particles, playing a key role in climate system and potentially affecting human health. There is a lack of data reported for Southern Italy and this work aims to fill this gap, focusing the attention on the long-term trends of OC and EC concentrations in PM2.5 and PM10, and on atmospheric processes and sources influencing seasonal variability. Measurements were taken at the Environmental-Climate Observatory of Lecce (SE Italy, 40°20‧8″N-18°07‧28″E, 37 m a.s.l.), regional station of the Global Atmosphere Watch program (GAW-WMO). Daily PM10 and PM2.5 samples were collected between July 2013 and July 2016. In addition, starting in December 2014, simultaneous equivalent Black Carbon (eBC) concentrations in PM10 were measured using a Multi Angle Absorption Photometer. A subset of 722 PM samples (361 for each size fraction) was analysed by using a thermo-optical method with a Sunset Laboratory OC/EC analyser, to determine elemental and organic carbon concentrations. The average PM10 and PM2.5 concentrations were 28.8 μg/m3 and 17.5 μg/m3. The average OC and EC concentrations in PM10 were 5.4 μg/m3 and 0.8 μg/m3, in PM2.5 these were 4.7 μg/m3 and 0.6 μg/m3. Carbonaceous content was larger during cold season with respect to warm season as well as secondary organic carbon (SOC) that was evaluated using the OC/EC minimum ratio method. SOC was mainly segregated in PM2.5 and represented 53% - 75% of the total OC. A subset of EC data was compared with eBC measurements, showing a good correlation (R2 = 0.80), however, eBC concentrations were higher than EC concentrations of an average factor of 1.95 (+/- 0.55 standard deviation). This could be explained by the presence of a contribution of Brown Carbon (BrC), for example from biomass burning, in eBC measurements. Weekly patterns showed a slight decrease of carbon content during weekends with respect to weekdays especially visible on eBC concentration due to the decrease of road traffic emissions. The daily patterns of hourly eBC concentrations showed a decrease in central diurnal hours, due to the cycle of planetary boundary-layer height, and concentrations peaks during rush hours due to road traffic emissions.

Physical and chemical characterization of Devonian gas shale. Quarterly status report, October 1-December 31, 1978

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zielinski, R.E.; Nance, S.W.

On shale samples from the WV-6 (Monongalia County, West Virginia) well, mean total gas yield was 80.4 ft/sup 3//ton. Mean hydrocarbon gas yield was 5.7 ft/sup 3//ton, 7% of total yield. Methane was the major hydrocarbon component and carbon dioxide the major nonhydrocarbon component. Oil yield was negligible. Clay minerals and organic matter were the dominant phases of the shale. Illite averages 76% of the total clay mineral content. This is detrital illite. Permeation of methane, parallel to the bedding direction for select samples from WV-5 (Mason County, West Virginia) well ranges from 10/sup -4/ to 10/sup -12/ darcys. Themore » permeability of these shales is affected by orgaic carbon content, density, particle orientation, depositional facies, etc. Preliminary studies of Devonian shale methane sorption rates suggest that these rates may be affected by shale porosity, as well as absorption and adsorption processes. An experimental system was designed to effectively simulate sorption of methane at natural reservoir conditions. The bulk density and color of select shales from Illinois, Appalachian and Michigan Basins suggest a general trend of decreasing density with increasing organic content. Black and grayish black shales have organic contents which normally exceed 1.0 wt %. Medium dark gray and gray shales generally have organic contents less than 1.0 wt %.« less

Biodegradability of fluorinated fire-fighting foams in water.

PubMed

Bourgeois, A; Bergendahl, J; Rangwala, A

2015-07-01

Fluorinated fire-fighting foams may be released into the environment during fire-fighting activities, raising concerns due to the potential environmental and health impacts for some fluorinated organics. The current study investigated (1) the biodegradability of three fluorinated fire-fighting foams, and (2) the applicability of current standard measures used to assess biodegradability of fluorinated fire-fighting foams. The biodegradability of three fluorinated fire-fighting foams was evaluated using a 28-day dissolved organic carbon (DOC) Die-Away Test. It was found that all three materials, diluted in water, achieved 77-96% biodegradability, meeting the criteria for "ready biodegradability". Defluorination of the fluorinated organics in the foam during biodegradation was measured using ion chromatography. It was found that the fluorine liberated was 1-2 orders of magnitude less than the estimated initial amount, indicating incomplete degradation of fluorinated organics, and incomplete CF bond breakage. Published biodegradability data may utilize biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC) metrics to quantify organics. COD and TOC of four fluorinated compounds were measured and compared to the calculated carbon content or theoretical oxygen demand. It was found that the standard dichromate-based COD test did not provide an accurate measure of fluorinated organic content. Thus published biodegradability data using COD for fluorinated organics quantification must be critically evaluated for validity. The TOC measurements correlated to an average of 91% of carbon content for the four fluorinated test substances, and TOC is recommended for use as an analytical parameter in fluorinated organics biodegradability tests. Copyright © 2015 Elsevier Ltd. All rights reserved.

Fuel Characterization of Newly Discovered Nigerian Coals

NASA Astrophysics Data System (ADS)

Bevan Nyakuma, Bemgba; Oladokun, Olagoke; Jauro, Aliyu; Damian Nyakuma, Denen

2017-07-01

This study seeks to characterize and highlight the fuel properties, rank, and classification of coals from Ihioma (IHM) and Ogboligbo (OGB) in Imo and Kogi states of Nigeria, respectively. The fuel properties were examined based on ultimate, proximate, and bomb calorific analyses. The results indicated that IHM coal contains comparatively higher C and H but lower O, N, and S content than OGB. In addition, the nitrogen (N) and sulphur (S) content for both coal samples were above 0.7 wt.% and 1.5 wt.%, respectively, which indicates high potential for pollutant emissions. Furthermore, the coal proximate properties were below 5 wt.% for Moisture; Volatiles (70 wt.%); Fixed Carbon (45 wt.%) and Ash (2.5 wt.%) on average. IHM coal has an HHV of 19.40 MJ/kg whereas OGB is 15.55 MJ/kg. This is due to the low carbon (C), hydrogen (H) and high oxygen (O) content in OGB whereas IHM contains higher VM and HHV. Furthermore, OGB presents better handling, storage, and transport potential. Furthermore, OGB has a higher fuel ratio and value index due to lower moisture, ash content, and volatiles. Based on the ASTM D388 standard, the coals were classified as Lignite (Brown) Low-Rank Coals (LRCs) with potential for energy recovery.

40 CFR 98.183 - Calculating GHG emissions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... = Carbon content of the lead ore, from the carbon analysis results (percent by weight, expressed as a... = Carbon content of the lead scrap, from the carbon analysis (percent by weight, expressed as a decimal... (tons). CFlux = Carbon content of the flux materials, from the carbon analysis (percent by weight...

A method for the assessment of long-term changes in carbon stock by construction of a hydropower reservoir.

PubMed

Bernardo, Julio Werner Yoshioka; Mannich, Michael; Hilgert, Stephan; Fernandes, Cristovão Vicente Scapulatempo; Bleninger, Tobias

2017-09-01

Sustainability of hydropower reservoirs has been questioned since the detection of their greenhouse gas (GHG) emissions which are mainly composed of carbon dioxide and methane. A method to assess the impact on the carbon cycle caused by the transition from a natural river system into a reservoir is presented and discussed. The method evaluates the long term changes in carbon stock instead of the current approach of monitoring and integrating continuous short term fluxes. A case study was conducted in a subtropical reservoir in Brazil, showing that the carbon content within the reservoir exceeds that of the previous landuse. The average carbon sequestration over 43 years since damming was 895 mg C m[Formula: see text] and found to be mainly due to storage of carbon in sediments. These results demonstrate that reservoirs have two opposite effects on the balance of GHGs. By storing organic C in sediments, reservoirs are an important carbon sink. On the other hand, reservoirs increase the flux of methane into the atmosphere. If the sediments of reservoirs could be used for long term C storage, reservoirs might have a positive effect on the balance of GHGs.

[Effects of grazing disturbance on soil active organic carbon in mountain forest-arid valley ecotone in the upper reaches of Minjiang River].

PubMed

Liu, Shan-Shan; Zhang, Xing-Hua; Gong, Yuan-Bo; Li, Yuan; Wang, Yan; Yin, Yan-Jie; Ma, Jin-Song; Guo, Ting

2014-02-01

Effects of grazing disturbance on the soil carbon contents and active components in the four vegetations, i.e., artificial Robinia pseudoacacia plantation, artificial poplar plantation, Berberis aggregate shrubland and grassland, were studied in the mountain forest-arid valley ecotone in the upper Minjiang River. Soil organic carbon and active component contents in 0-10 cm soil layer were greater than in 10-20 cm soil layer at each level of grazing disturbance. With increasing the grazing intensity, the total organic carbon (TOC), light fraction organic carbon (LFOC), particulate organic carbon (POC) and easily oxidized carbon (LOC) contents in 0-10 cm soil layer decreased gradually in the artificial R. pseudoacacia plantation. The LFOC content decreased, the POC content increased, and the TOC and LOC contents decreased initially and then increased with increasing the grazing intensity in the artificial poplar plantation. The POC content decreased, and the TOC, LFOC and LOC contents decreased initially and then increased with increasing the grazing intensity in the B. aggregate shrubland. The POC and TOC contents decreased, and the LFOC and LOC contents decreased initially and then increased with increasing the grazing intensity in the grassland. The decreasing ranges of LOC, LFOC and POC contents were 0.1-7.9 times more than that of TOC content. There were significant positive relationships between TOC and LOC, LFOC and POC, suggesting that the active organic carbon components could reflect the change of soil total carbon content.

Impact of soil properties on selected pharmaceuticals adsorption in soils

NASA Astrophysics Data System (ADS)

Kodesova, Radka; Kocarek, Martin; Klement, Ales; Fer, Miroslav; Golovko, Oksana; Grabic, Roman; Jaksik, Ondrej

2014-05-01

The presence of human and veterinary pharmaceuticals in the environment has been recognized as a potential threat. Pharmaceuticals may contaminate soils and consequently surface and groundwater. Study was therefore focused on the evaluation of selected pharmaceuticals adsorption in soils, as one of the parameters, which are necessary to know when assessing contaminant transport in soils. The goals of this study were: (1) to select representative soils of the Czech Republic and to measure soil physical and chemical properties; (2) to measure adsorption isotherms of selected pharmaceuticals; (3) to evaluate impact of soil properties on pharmaceutical adsorptions and to propose pedotransfer rules for estimating adsorption coefficients from the measured soil properties. Batch sorption tests were performed for 6 selected pharmaceuticals (beta blockers Atenolol and Metoprolol, anticonvulsant Carbamazepin, and antibiotics Clarithromycin, Trimetoprim and Sulfamethoxazol) and 13 representative soils (soil samples from surface horizons of 11 different soil types and 2 substrates). The Freundlich equations were used to describe adsorption isotherms. The simple correlations between measured physical and chemical soil properties (soil particle density, soil texture, oxidable organic carbon content, CaCO3 content, pH_H2O, pH_KCl, exchangeable acidity, cation exchange capacity, hydrolytic acidity, basic cation saturation, sorption complex saturation, salinity), and the Freundlich adsorption coefficients were assessed using Pearson correlation coefficient. Then multiple-linear regressions were applied to predict the Freundlich adsorption coefficients from measured soil properties. The largest adsorption was measured for Clarithromycin (average value of 227.1) and decreased as follows: Trimetoprim (22.5), Metoprolol (9.0), Atenolol (6.6), Carbamazepin (2.7), Sulfamethoxazol (1.9). Absorption coefficients for Atenolol and Metoprolol closely correlated (R=0.85), and both were also related to absorption coefficients of Carbamazepin (R=0.67 and 0.68). Positive correlation was found between Trimetoprim absorption coefficients and Atenolol, Metoprolol or Carbamazepin absorption coefficients. The negative relationship was found between absorption coefficients of Sulfomethoxazol and Clarithromycin (R=-0.80). Sulfamethoxazol absorption coefficient was negatively related to pH_H2O, pH_KCL or sorption complex saturation and positively to the hydrolytic acidity or exchangeable acidity. Trimetoprim absorption coefficient was positively related to the oxidable organic carbon content, cation exchange capacity, basic cation saturation or silt content and negatively to particle density or sand content. Clarithromycin absorption coefficient was positively related to pH_H2O, pH_KCL, CaCO3 content, basic cation saturation or sorption complex saturation and negatively to hydrolytic acidity or exchangeable acidity. Atenolol and Metoprolol absorption coefficients were positively related to the oxidable organic carbon content, cation exchange capacity, basic cation saturation, salinity, clay content or silt content, and negatively to the particle density or sand content. Finally Carbamazepin absorption coefficient was positively related to the oxidable organic carbon content, cation exchange capacity or basic cation saturation, and negatively to the particle density or sand content. Evaluated pedotransfer rules for different pharmaceuticals included different sets of soil properties. Absorption coefficients could be predicted from: the hydrolytic acidity (Sulfamethoxazol), the oxidable organic carbon content (Trimetoprim and Carbamazepin), the oxidable organic carbon content, hydrolytic acidity and cation exchange capacity (Clarithromycin), the basic cation saturation (Atenolol and Metoprolol). Acknowledgement: Authors acknowledge the financial support of the Czech Science Foundation (Project No. 13-12477S).

Evaluation of biomass quality of selected woody species depending on the soil enrichment practice

NASA Astrophysics Data System (ADS)

Stolarski, Mariusz J.; Krzyżaniak, Michał; Załuski, Dariusz; Niksa, Dariusz

2018-01-01

Perennial energy crops are a source of the bio-mass used to generate energy. The aim of this study was to determine the chemical and thermophysical parameters of short rotation woody crops (black locust, poplar and willow), depending on soil enrichment practice (mineral fertilisation, lignin and mycorrhiza), in three- and four-year harvest cycles. In the study, the thermophysical properties and elemental composition of the biomass were determined. All analyses were performed in trip-licate according to the standards. The fresh black locust biomass had the lowest moisture content, which resulted in the best lower heating value (10.16 MJ kg-1, on average) in the four-year harvest cycle. The poplar biomass had the greatest higher heating value, fixed carbon, carbon and ash content, the highest concentrations of which were found in the biomass in which lignin was applied (2.00% d.m.). On the other hand, the willow biomass contained the lowest concentrations of ash and fixed carbon. Soil enrichment significantly differentiated the quality parameters of black locust, poplar and willow. This effect is of particular importance to those who grow and use biomass as a fuel.

Photosynthetic light reactions increase total lipid accumulation in carbon-supplemented batch cultures of Chlorella vulgaris.

PubMed

Woodworth, Benjamin D; Mead, Rebecca L; Nichols, Courtney N; Kolling, Derrick R J

2015-03-01

Microalgae are an attractive biofuel feedstock because of their high lipid to biomass ratios, lipid compositions that are suitable for biodiesel production, and the ability to grow on varied carbon sources. While algae can grow autotrophically, supplying an exogenous carbon source can increase growth rates and allow heterotrophic growth in the absence of light. Time course analyses of dextrose-supplemented Chlorella vulgaris batch cultures demonstrate that light availability directly influences growth rate, chlorophyll production, and total lipid accumulation. Parallel photomixotrophic and heterotrophic cultures grown to stationary phase reached the same amount of biomass, but total lipid content was higher for algae grown in the presence of light (an average of 1.90 mg/mL vs. 0.77 mg/mL over 5 days of stationary phase growth). Copyright © 2014 Elsevier Ltd. All rights reserved.

Blue carbon stocks in Baltic Sea eelgrass (Zostera marina) meadows

NASA Astrophysics Data System (ADS)

Röhr, Maria Emilia; Boström, Christoffer; Canal-Vergés, Paula; Holmer, Marianne

2016-11-01

Although seagrasses cover only a minor fraction of the ocean seafloor, their carbon sink capacity accounts for nearly one-fifth of the total oceanic carbon burial and thus play a critical structural and functional role in many coastal ecosystems. We sampled 10 eelgrass (Zostera marina) meadows in Finland and 10 in Denmark to explore seagrass carbon stocks (Corg stock) and carbon accumulation rates (Corg accumulation) in the Baltic Sea area. The study sites represent a gradient from sheltered to exposed locations in both regions to reflect expected minimum and maximum stocks and accumulation. The Corg stock integrated over the top 25 cm of the sediment averaged 627 g C m-2 in Finland, while in Denmark the average Corg stock was over 6 times higher (4324 g C m-2). A conservative estimate of the total organic carbon pool in the regions ranged between 6.98 and 44.9 t C ha-1. Our results suggest that the Finnish eelgrass meadows are minor carbon sinks compared to the Danish meadows, and that majority of the Corg produced in the Finnish meadows is exported. Our analysis further showed that > 40 % of the variation in the Corg stocks was explained by sediment characteristics, i.e. dry density, porosity and silt content. In addition, our analysis show that the root : shoot ratio of Z. marina explained > 12 % and the contribution of Z. marina detritus to the sediment surface Corg pool explained > 10 % of the variation in the Corg stocks. The mean monetary value for the present carbon storage and carbon sink capacity of eelgrass meadows in Finland and Denmark, were 281 and 1809 EUR ha-1, respectively. For a more comprehensive picture of seagrass carbon storage capacity, we conclude that future blue carbon studies should, in a more integrative way, investigate the interactions between sediment biogeochemistry, seascape structure, plant species architecture and the hydrodynamic regime.

Organic sedimentation in modern lacustrine systems: A case study from Lake Malawi, East Africa

USGS Publications Warehouse

Ellis, Geoffrey S.; Barry J. Katz,; Christopher A. Scholz,; Peter K. Swart,

2015-01-01

This study examines the relationship between depositional environment and sedimentary organic geochemistry in Lake Malawi, East Africa, and evaluates the relative significance of the various processes that control sedimentary organic matter (OM) in lacustrine systems. Total organic carbon (TOC) concentrations in recent sediments from Lake Malawi range from 0.01 to 8.80 wt% and average 2.83 wt% for surface sediments and 2.35 wt% for shallow core sediments. Hydrogen index (HI) values as determined by Rock-Eval pyrolysis range from 0 to 756 mg HC g−1 TOC and average 205 mg HC g−1 TOC for surface sediments and 228 mg HC g−1 TOC for shallow core samples. On average, variations in primary productivity throughout the lake may account for ~33% of the TOC content in Lake Malawi sediments (as much as 1 wt% TOC), and have little or no impact on sedimentary HI values. Similarly, ~33% to 66% of the variation in TOC content in Lake Malawi sediments appears to be controlled by anoxic preservation of OM (~1–2 wt% TOC), although some component of the water depth–TOC relationship may be due to physical sediment transport processes. Furthermore, anoxic preservation has a minimal effect on HI values in Lake Malawi sediments. Dilution of OM by inorganic sediment may account for ~16% of variability in TOC content in Lake Malawi sediments (~0.5 wt% TOC). The effect of inputs of terrestrial sediment on the organic character of surface sediments in these lakes is highly variable, and appears to be more closely related to the local depositional environment than the regional flux of terrestrial OM. Total nitrogen and TOC content in surface sediments collected throughout the lake are found to be highly correlated (r2 = 0.95), indicating a well-homogenized source of OM to the lake bottom. The recurring suspension and deposition of terrestrial sediment may account for significant amounts of OM deposited in offshore regions of the lake. This process effectively separates denser inorganic sediment from less dense OM and allows terrestrial OM to preferentially be transported farther offshore. The conclusion is that for the organic carbon content in these regions to be elevated a mixed terrestrial-lacustrine origin is required. The hydrodynamic separation of mineral and organic constituents is most pronounced in regions with shallow bathymetric gradients, consistent with previous findings from Lake Tanganyika.

Diamond growth from oxidized carbon sources beneath the Northern Slave Craton, Canada: A δ 13C-N study of eclogite-hosted diamonds from the Jericho kimberlite

NASA Astrophysics Data System (ADS)

Smart, Katie A.; Chacko, Thomas; Stachel, Thomas; Muehlenbachs, Karlis; Stern, Richard A.; Heaman, Larry M.

2011-10-01

Diamonds from high- and low-MgO groups of eclogite xenoliths from the Jericho kimberlite, Slave Craton, Canada were analyzed for carbon isotope compositions and nitrogen contents. Diamonds extracted from the two groups show remarkably different nitrogen abundances and δ 13C values. While diamonds from high-MgO eclogites have low nitrogen contents (5-82 ppm) and extremely low δ 13C values clustering at ˜-40‰, diamonds from the low-MgO eclogites have high nitrogen contents (>1200 ppm) and δ 13C values from -3.5‰ to -5.3‰. Coupled cathodoluminescence (CL) imaging and SIMS analysis of the Jericho diamonds provides insight into diamond growth processes. Diamonds from the high-MgO eclogites display little CL structure and generally have constant δ 13C values and nitrogen contents. Some of these diamonds have secondary rims with increasing δ 13C values from -40‰ to ˜-34‰, which suggests secondary diamond growth occurred from an oxidized growth medium. The extreme negative δ 13C values of the high-MgO eclogite diamonds cannot be produced by Rayleigh isotopic fractionation of average mantle-derived carbon (-5‰) or carbon derived from typical organic matter (˜-25‰). However, excursions in δ 13C values to -60‰ are known in the organic sedimentary record at ca. 2.7 and 2.0 Ga, such that diamonds from the high-MgO eclogites could have formed from similar organic matter brought into the Slave lithospheric mantle by subduction. SIMS analyses of a diamond from a low-MgO eclogite show an outer core with systematic rimwards increases in δ 13C values coupled with decreases in nitrogen contents, and a rim with pronounced alternating growth zones. The coupled δ 13C-nitrogen data suggest that the diamond precipitated during fractional crystallization from an oxidized fluid/melt from which nitrogen was progressively depleted during growth. Model calculations of the co-variation of δ 13C-N yielded a partition coefficient ( KN) value of 5, indicating that nitrogen is strongly compatible in diamond relative to the growth medium. δ 13C values of diamond cores (-4‰) dictate the growth medium had higher δ 13C values than primary mantle-derived carbon. Therefore, possible carbon sources for the low-MgO eclogite diamonds include oxidized mantle-derived (e.g. protokimberlite or carbonatite) fluids/melts that underwent some fractionation during migration or, devolatilized subducted carbonates.

Ozone-induced changes in natural organic matter (NOM) structure

USGS Publications Warehouse

Westerhoff, P.; Debroux, J.; Aiken, G.; Amy, G.

1999-01-01

Hydrophobic organic acids (combined humic and fulvic acids), obtained from an Antarctic Lake with predominantly microbially derived organic carbon sources and two US fiver systems with terrestrial organic carbon sources, were ozonated. Several analyses, including 13C-NMR, UV absorbance, fluorescence, hydrophobic/transphilic classification, and potentiometric titrations, were performed before and after ozonation. Ozonation reduced aromatic carbon content, selectively reducing phenolic carbon content. Ozonation of the samples resulted in increased aliphatic, carboxyl, plus acetal and ketal anomeric carbon content and shifted towards less hydrophobic compounds.Hydrophobic organic acids (combined humic and fulvic acids), obtained from an Antarctic Lake with predominantly microbially derived organic carbon sources and two US river systems with terrestrial organic carbon sources, were ozonated. Several analyses, including 13C-NMR, UV absorbance, fluorescence, hydrophobic/transphilic classification, and potentiometric titrations, were performed before and after ozonation. Ozonation reduced aromatic carbon content, selectively reducing phenolic carbon content. Ozonation of the samples resulted in increased aliphatic, carboxyl, plus acetal and ketal anomeric carbon content and shifted towards less hydrophobic compounds.

Combustion and kinetic parameters estimation of torrefied pine, acacia and Miscanthus giganteus using experimental and modelling techniques.

PubMed

Wilk, Małgorzata; Magdziarz, Aneta; Gajek, Marcin; Zajemska, Monika; Jayaraman, Kandasamy; Gokalp, Iskender

2017-11-01

A novel approach, linking both experiments and modelling, was applied to obtain a better understanding of combustion characteristics of torrefied biomass. Therefore, Pine, Acacia and Miscanthus giganteus have been investigated under 260°C, 1h residence time and argon atmosphere. A higher heating value and carbon content corresponding to a higher fixed carbon, lower volatile matter, moisture content, and ratio O/C were obtained for all torrefied biomass. TGA analysis was used in order to proceed with the kinetics study and Chemkin calculations. The kinetics analysis demonstrated that the torrefaction process led to a decrease in Ea compared to raw biomass. The average Ea of pine using the KAS method changed from 169.42 to 122.88kJ/mol. The changes in gaseous products of combustion were calculated by Chemkin, which corresponded with the TGA results. The general conclusion based on these investigations is that torrefaction improves the physical and chemical properties of biomass. Copyright © 2017 Elsevier Ltd. All rights reserved.

Crater-lake Santa Maria del Oro as a Pristine Reference for Persistent Organic Pollutants (POP' s) and Heavy Metals Content in Environmental Investigations in Western Mexico (Project Conacyt-Semarnat 2002-C01-0463, in Progress).

NASA Astrophysics Data System (ADS)

Zarate-Del Valle, P. F.; Gomez-Hermosillo, C. M.; Venegas-Garcia, D. J.

2007-12-01

Santa Maria del Oro Lake ( SMO) (21.37° N, 104.57° W; 750 m a.s.l.) is a quaternary crater-lake located at western Mexico in the natural border between two geological provinces: the plio-quaternary Trans-Mexican Volcanic Belt and the oligo-miocenic silicic volcanic province Sierra Madre Occidental. SMO, a tropical freshwater lake, is a warm-monomictic lake having a diameter of ca. 2 km and a mean depth at the depocenter of ca. 60 m, where three benthos cores were recovered. Contents of POP' s, total inorganic carbon (TIC), total organic carbon (TOC) and heavy metals were analyzed. Geochemistry and mineralogy also were studied in shallow sediments which corresponded to the decade of 50-60's, otherwise the beginning of industrial development of central Mexico; which is considered the possible source of emission of POP' s and heavy metals. Dioxin, furan, plaguicides and PCB' s contents were analyzed by a GC-MS applying USEPA methods. In the first 40 cm (n= 20) of the sedimentary column ( SC) the absence of POP' s was evidenced, applying a method detection limit ( MDL) of 5 μ g/ml for dioxin, furan and PCB' s. For plaguicides like chlordane and toxaphene the MDL was 0.5 μ g/ml and for plaguicides like DDT, aldrin, endrin, dieldrin, heptachlore and mirex the MDL was 5 μ g/ml. The MDL for HCB was 1 μ g/ml. The average (n= 30) for TIC, TOC and total carbon (TC) for the first 40 cm of the SC is as follows: TIC 2.4 %, TOC 3.7 % and TC 6.12 %. The average (n= 20) content (in ppm) of heavy metals for the first 20 cm of the SC is as follows: As 5.97, Cr 27.54, Cu 16.31, Ni 12.29, Pb 21.35 and Zn 82.46. These contents are roughly similar to the clarke of these metals in volcanic rocks. After the criteria of severe effect level ( SEL) of heavy metal in sediments, the content of these metals is below SEL levels. These results permit us to conclude that the sediments of SMO can be considered in unaffected state with respect to antropogenic contamination like POP' s and heavy metals. Consequently, Santa Maria del Oro Lake can be considered as a pristine reference in paleo-ecological and environmental investigations in western Mexico.

Characteristics of organic carbon accumulation in subtropical seagrass meadows

NASA Astrophysics Data System (ADS)

Tanaya, T.; Watanabe, K.; Yamamoto, S.; Hongo, C.; Kayanne, H.; Kuwae, T.

2016-02-01

The carbon sequestrated in marine ecosystems has been termed "blue carbon", and seagrass meadows are one of the most dominant blue carbon stocks. Globally, the major distribution sites of seagrass meadows are coral reef flats, where it is technically difficult to quantify organic carbon in carbonate sediments. Since blue carbon stocks have been estimated to date based on seagrass biomass and fine sediments (<1 mm), no studies have measured total carbon stocks, including coarse sediments (1> mm) in seagrass meadows. To solve this problem, we developed a new box corer which can facilitate to obtain the intact cores structured by both sediments and seagrass bodies. Using the core samples taken in subtropical seagrass meadows, located off Ishigaki Island, Japan, we measured total organic carbon mass (TOCmass) and stable isotope ratios (δ13C) of total sedimentary organic matter (SOM) and estimated their sources and controlling factors. The averaged TOCmass of top 15 cm SOM including living seagrasses was 940±480 gC/m2. The live seagrass biomass accounted for only 14±14wt%, whereas the dead biomass (>2 mm), coarse sediments (>1 mm except for dead plant structures >2 mm) and fine sediments (<1 mm) accounted for 3±4wt%, 19±13wt%, and 63±14wt%, respectively. The dead biomass and coarse sediments, which have not yet been included in the past estimations, accounted for about 22wt% of the averaged TOCmass. Total organic carbon content (TOC%) of mixture of the dead biomass, coarse sediments and fine sediments increased with increasing the live seagrass biomass (R = 0.66, n = 13, p = 0.014). The live seagrass biomass was one of the controlling factors of blue carbon stocks at the sites. Using a Bayesian isotopic mixing model, we estimated that the contribution of seagrass-derived carbon to total sedimentary organic carbon was about 70%. The enrichment of sediment organic carbon with increasing the live seagrass biomass was mainly due to the increase of seagrass-derived organic carbon. These results suggest that blue carbon stocks can be increased by conservation or restoration of seagrass meadows in subtropical coasts.

[Distribution of organic carbon and carbon fixed strength of phytoplankton in Enteromorpha prolifera outbreak area of the Western South Yellow Sea, 2008].

PubMed

Xia, Bin; Ma, Shao-Sai; Chen, Ju-Fa; Zhao, Jun; Chen, Bi-Juan; Wang, Fang

2010-06-01

Based on the analysis of dissolved organic carbon (DOC), particulate organic carbon (POC) and particulate nitrogen (PN) of the samples collected from stations in Enteromorpha prolifera outbreak area of the Western South Yellow Sea during the period August 9-13 of 2008, combining with the data of environmental hydrology, the horizontal distribution, source and influential factors of organic carbon and carbon fixed strength of phytoplankton were discussed. The results showed that the concentrations of DOC and POC ranged from 1.55 mg/L to 3.22 mg/L, 0.11 mg/L to 0.68 mg/L, with average values of 2.44 mg/L and 0.27 mg/L. The horizontal distributions of DOC and POC were similar in study area. The concentrations of DOC and POC in coastal area were higher than that in the outer sea and the concentrations of DOC and POC at surface water layer were higher than those at the bottom water layer. There were a positive correlation between POC and TSS, indicating that the concentrations and source of TSS were main factors for the POC. According to the univariate linear regression model between POC and PN, the concentrations of particulate inorganic nitrogen (PIN) were evaluated. Removing the content of PIN in the samples, the average POC/PON values in most coastal waters were less than 8, combining with the values of POC/chlorophyll a, suggesting that the marine primary production were the important source of POC in most coastal waters, and the presence of degraded organic matter which derived from degraded Enteromorph prolifera was in the latter period of green tide outbreak. The results of evaluated carbon fixed strength based on primary productivity showed that carbon fixed strength of phytoplankton in Enteromorpha prolifera outbreak area of the Western South Yellow Sea ranged from 167 mg/(m2 x d) to 2017 mg/(m2 x d), with the average of 730 mg/(m2 x d). The daily carbon fixed quantities of the study area were up to 2.95 x 10(4) t. Then the daily carbon fixed quantities of the Yellow Sea were 28.03 x 10(4) t.

Spatial assessment of soil organic carbon and physicochemical properties in a horticultural orchard at arid zone of India using geostatistical approaches.

PubMed

Singh, Akath; Santra, Priyabrata; Kumar, Mahesh; Panwar, Navraten; Meghwal, P R

2016-09-01

Soil organic carbon (SOC) is a major indicator of long-term sustenance of agricultural production system. Apart from sustaining productivity, SOC plays a crucial role in context of climate change. Keeping in mind these potentials, spatial variation of SOC contents of a fruit orchard comprising several arid fruit plantations located at arid region of India is assessed in this study through geostatistical approaches. For this purpose, surface and subsurface soil samples from 175 locations from a fruit orchard spreading over 14.33 ha area were collected along with geographical coordinates. SOC content and soil physicochemical properties of collected soil samples were determined followed by geostatistical analysis for mapping purposes. Average SOC stock density of the orchard was 14.48 Mg ha(-1) for 0- to 30-cm soil layer ranging from 9.01 Mg ha(-1) in Carissa carandas to 19.52 Mg ha(-1) in Prosopis cineraria block. Range of spatial variation of SOC content was found about 100 m, while two other soil physicochemical properties, e.g., pH and electrical conductivity (EC) also showed similar spatial trend. This indicated that minimum sampling distance for future SOC mapping programme may be kept lower than 100 m for better accuracy. Ordinary kriging technique satisfactorily predicted SOC contents (in percent) at unsampled locations with root-mean-squared residual (RMSR) of 0.35-0.37. Co-kriging approach was found slightly superior (RMSR = 0.26-0.28) than ordinary kriging for spatial prediction of SOC contents because of significant correlations of SOC contents with pH and EC. Uncertainty of SOC estimation was also presented in terms of 90 % confidence interval. Spatial estimates of SOC stock through ordinary kriging or co-kriging approach were also found with low uncertainty of estimation than non-spatial estimates, e.g., arithmetic averaging approach. Among different fruit block plantations of the orchard, the block with Prosopis cineraria ('khejri') has higher SOC stock density than others.

Description, calibration and sensitivity analysis of the local ecosystem submodel of a global model of carbon and nitrogen cycling and the water balance in the terrestrial biosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kercher, J.R.; Chambers, J.Q.

1995-10-01

We have developed a geographically-distributed ecosystem model for the carbon, nitrogen, and water dynamics of the terrestrial biosphere TERRA. The local ecosystem model of TERRA consists of coupled, modified versions of TEM and DAYTRANS. The ecosystem model in each grid cell calculates water fluxes of evaporation, transpiration, and runoff; carbon fluxes of gross primary productivity, litterfall, and plant and soil respiration; and nitrogen fluxes of vegetation uptake, litterfall, mineralization, immobilization, and system loss. The state variables are soil water content; carbon in live vegetation; carbon in soil; nitrogen in live vegetation; organic nitrogen in soil and fitter; available inorganic nitrogenmore » aggregating nitrites, nitrates, and ammonia; and a variable for allocation. Carbon and nitrogen dynamics are calibrated to specific sites in 17 vegetation types. Eight parameters are determined during calibration for each of the 17 vegetation types. At calibration, the annual average values of carbon in vegetation C, show site differences that derive from the vegetation-type specific parameters and intersite variation in climate and soils. From calibration, we recover the average C{sub v} of forests, woodlands, savannas, grasslands, shrublands, and tundra that were used to develop the model initially. The timing of the phases of the annual variation is driven by temperature and light in the high latitude and moist temperate zones. The dry temperate zones are driven by temperature, precipitation, and light. In the tropics, precipitation is the key variable in annual variation. The seasonal responses are even more clearly demonstrated in net primary production and show the same controlling factors.« less

Dolomitization of felsic volcaniclastic rocks in continental strata: A study from the Lower Cretaceous of the A'nan Sag in Er'lian Basin, China

NASA Astrophysics Data System (ADS)

Zhu, Shifa; Yue, Hui; Zhu, Xiaomin; Sun, Shuyang; Wei, Wei; Liu, Xin; Jia, Ye

2017-05-01

Dolomitization of fine-grained volcaniclastic rocks is common in the Lower Cretaceous of the A'nan Sag in the Er'lian Basin of China. Analysis of core samples shows that the organic-rich volcaniclastic rocks are mainly composed of reworked felsic volcanic materials and terrigenous clay minerals. The fine-grained volcaniclastic rocks can be divided into four types: volcaniclastic rocks without carbonatization, volcaniclastic rocks with ferroan dolomites, dolomitized and calcified volcaniclastic rocks, and calcified volcaniclastic rocks. The parent rocks of the volcaniclastic rocks have high silicon and potassium contents and low iron and magnesium contents, and are probably felsic magma of the calc-alkaline series. The average values of δ13CPDB of the carbonate minerals are about 3.13‰; the average values of δ18OPDB are about - 16.74‰. The compositions of C and O isotopes are probably influenced by bacterial methanogenesis. Iron, magnesium, and calcium are probably derived from illitization of terrigenous smectite. A model for dolomitization of felsic volcaniclastic rock is proposed, including three stages: 1) mixed sedimentation and bacterial methanogenesis (< 75 °C); 2) transformation of clay minerals (> 70 °C) and dolomitization (75 to 97 °C); and 3) dissolution. Late dissolution of authigenic carbonate minerals, creating abundant secondary pores, is significant for hydrocarbon accumulation.

Long-term influence of tillage and fertilization on net carbon dioxide exchange rate on two soils with different textures.

PubMed

Feiziene, Dalia; Feiza, Virginijus; Slepetiene, Alvyra; Liaudanskiene, Inga; Kadziene, Grazina; Deveikyte, Irena; Vaideliene, Asta

2011-01-01

The importance of agricultural practices to greenhouse gas mitigation is examined worldwide. However, there is no consensus on soil organic carbon (SOC) content and CO emissions as affected by soil management practices and their relationships with soil texture. No-till (NT) agriculture often results in soil C gain, though, not always. Soil net CO exchange rate (NCER) and environmental factors (SOC, soil temperature [T], and water content [W]), as affected by soil type (loam and sandy loam), tillage (conventional, reduced, and NT), and fertilization, were quantified in long-term field experiments in Lithuania. Soil tillage and fertilization affected total CO flux (heterotrophic and autotrophic) through effect on soil SOC sequestration, water, and temperature regime. After 11 yr of different tillage and fertilization management, SOC content was 23% more in loam than in sandy loam. Long-term NT contributed to 7 to 27% more SOC sequestration on loam and to 29 to 33% more on sandy loam compared with reduced tillage (RT) or conventional tillage (CT). Soil water content in loam was 7% more than in sandy loam. Soil gravimetric water content, averaged across measurement dates and fertilization treatments, was significantly less in NT than CT and RT in both soils. Soil organic carbon content and water storage capacity of the loam and sandy loam soils exerted different influences on NCER. The NCER from the sandy loam soil was 13% greater than that from the loam. In addition, NCER was 4 to 9% less with NT than with CT and RT systems on both loam and sandy loam soils. Application of mineral NPK fertilizers promoted significantly greater NCER from loam but suppressed NCER by 15% from sandy loam. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

[Study on pollution characteristics of carbonaceous aerosols in Xi'an City during the spring festival].

PubMed

Zhou, Bian-Hong; Zhang, Cheng-Zhong; Wang, Ge-Hui

2013-02-01

The samples of PM2.5 with 8 times periods were collected using Automated Cartridge Collection Unit (ACCU) of Rupprecht& Patashnick (R&P)Corporation, and monitored by R&P1400a instrument of TEOM series online during 2011 Spring Festival in Xi'an city. The organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and water-insoluble organic carbon (WIOC) contents of 3 h integrated PM2.5 were analyzed to evaluate the influence of firework display on the carbonaceous components in urban air. The mass concentration of PM2.5 was found increased significantly from 00:00 A. M. to 02:59 A. M. at the Chinese Lunar New Year's Eve than the non-firework periods, reaching 1514.8 microg.m-3 at 01:00 A. M. The mass concentrations of OC, EC, WSOC, and WIOC during the same time period were 123.3 microg.m-3, 18.6 microg.m-3, 66.7 microg.m-3, and 56.6 microg.m-3, about 1.7, 1.2, 1.4, and 2.2 times higher than the average in normal days, respectively. Correlation analysis among WSOC, OC, and EC contents in PM25 showed that firework emission was an obvious source of carbonaceous aerosol in the Spring Festival vacation. However, it only contributes to 9. 4% for aerosol in fireworks emission.

The geochemical record of the last 17,000 years in the Guaymas Basin, Gulf of California

USGS Publications Warehouse

Dean, W.E.

2006-01-01

Sediments deposited on the western slope of the Guaymas Basin in the central Gulf of California are composed predominantly of detrital clastic material and biogenic silica (biopal), with minor organic material (average of 2.8% organic carbon) and calcium carbonate. The CaCO3 is derived from calcareous plankton and is highly variable ranging from 0% to 16%. In general, the CaCO3 content of the sediments varies inversely with the biopal content, reflecting the relative abundance of calcareous and siliceous plankton in the photic zone. Siliceous plankton dominate when winds are predominantly out of the northwest producing strong upwelling. Calcareous plankton indicates weak southeasterly winds that bring warm, tropical Pacific surface water into the Gulf. Based mainly on relative abundances of biopal and CaCO3, the sediments deposited over the last 17,000 years in the western Guaymas Basin can be divided into five intervals. In general, the sediments in the intervals with high biopal and low CaCO3 are laminated, but this is not always true. Unlike most other continental margins of the world with well-developed oxygen minimum zones where highest concentrations of organic carbon and redox-sensitive trace metals occur in laminated sediments, the laminated sediments on the anoxic slope of the western Guaymas Basin do not always have the highest concentrations of organic carbon and trace metals such as Mo and Cd.

Empirical Leucine-to-Carbon Conversion Factors for Estimating Heterotrophic Bacterial Production: Seasonality and Predictability in a Temperate Coastal Ecosystem▿

PubMed Central

Calvo-Díaz, Alejandra; Morán, Xosé Anxelu G.

2009-01-01

Leucine-to-carbon conversion factors (CFs) are needed for converting substrate incorporation into biomass production of heterotrophic bacteria. During 2006 we performed 20 dilution experiments for determining the spatiotemporal variability of empirical CFs in temperate Atlantic coastal waters. Values (0.49 to 1.92 kg C mol Leu−1) showed maxima in autumn to early winter and minima in summer. Spatially averaged CFs were significantly negatively correlated with in situ leucine incorporation rates (r = −0.91) and positively correlated with phosphate concentrations (r = 0.76). These relationships, together with a strong positive covariation between cell-specific leucine incorporation rates and carbon contents (r = 0.85), were interpreted as a strategy to maximize survival through protein synthesis and low growth rates under nutrient limitation (low CFs) until favorable conditions stimulate cell division relative to protein synthesis (high CFs). A multiple regression with in situ leucine incorporation rates and cellular carbon contents explained 96% of CF variance in our ecosystem, suggesting their potential prediction from more easily measurable routine variables. The use of the theoretical CF of 1.55 kg C mol Leu−1 would have resulted in a serious overestimation (73%) of annual bacterial production rates. Our results emphasize the need for considering the temporal scale in CFs for bacterial production studies. PMID:19304821

Ultra-Smooth Nanostructured Diamond Films Deposited from He/H2/CH4/N2 Microwave Plasmas

PubMed Central

Konovalov, Valery V.; Melo, Andrew; Catledge, Shane A.; Chowdhury, Shafiul

2008-01-01

Addition of He to a high CH4 content (10.7 vol%) H2/CH4/N2 feedgas mixture for microwave plasma chemical vapor deposition produced hard (56–72 GPa), ultra-smooth nanostructured diamond films on Ti-6Al-4V alloy substrates. Upon increase in He content up to 71 vol%, root mean squared (RMS) surface roughness of the film decreased to 9–10 nm and average diamond grain size to 5–6 nm. Our studies show that increased nanocrystallinity with He addition in plasma is related to plasma dilution, enhanced fragmentation of carbon containing species, and enhanced formation of CN radical. PMID:16573106

Highly Efficient Red-Emitting Carbon Dots with Gram-Scale Yield for Bioimaging.

PubMed

Ding, Hui; Wei, Ji-Shi; Zhong, Ning; Gao, Qing-Yu; Xiong, Huan-Ming

2017-11-07

Carbon dots (CDs) are a new class of photoluminescent (PL), biocompatible, environment-friendly, and low-cost carbon nanomaterials. Synthesis of highly efficient red-emitting carbon dots (R-CDs) on a gram scale is a great challenge at present, which heavily restricts the wide applications of CDs in the bioimaging field. Herein, R-CDs with a high quantum yield (QY) of 53% are produced on a gram scale by heating a formamide solution of citric acid and ethylenediamine. The as-prepared R-CDs have an average size of 4.1 nm and a nitrogen content of about 30%, with an excitation-independent emission at 627 nm. After detailed characterizations, such strong red fluorescence is ascribed to the contribution from the nitrogen- and oxygen-related surface states and the nitrogen-derived structures in the R-CD cores. Our R-CDs show good photostability and low cytotoxicity, and thus they are excellent red fluorescence probes for bioimaging both in vitro and in vivo.

Anthropogenic Black Carbon Emission Increase during the Last 150 Years at Coastal Jiangsu, China

PubMed Central

Bao, Kunshan; Shen, Ji; Wang, Guoping; Gao, Chuanyu

2015-01-01

Black carbon (BC) is one of the major drivers of climate change and a useful indicator of environmental pollution from industrialization, and thus it is essential to reconstruct the historical trend in BC flux to better understand its impact. The Yancheng coastal wetland reserve in Jiangsu province is an area sensitive to global sea level change and is also located in the most developed as well as most polluted region of China. We investigated the concentration and historical flux of BC over the past 150 years through geochemical analysis of two 210Pb-dated sediment cores from Yancheng coastal wetland. Measured BC contents ranged from 0.24 mg g-1 to 1.41 mg g-1 with average values of 0.51mg g-1-0.69 mg g-1, and BC fluxes ranged from 0.69 g m-2 yr-1 to 11.80 g m-2 yr-1 with averages of 2.94g m-2 yr-1-3.79 g m-2 yr-1. These values are consistent with other records worldwide. Both BC content and flux show a gradual and continuous increase over time and clearly reflect increased emissions from anthropogenic activities. The BC records have a significant peak in recent years (from 2000 to 2007), which is accompanied by the sharp increase of energy consumption and total carbon emission in the region. It is reasonable to conclude that changes in BC from increasing human activities have controlled BC fluxes during the last 150 years. Industrial contamination, especially BC emission, in the coastal region of eastern China should be taken into account when developing management strategies for protecting the natural environment. PMID:26200665

Survey of mercury, cadmium and lead content of household batteries.

PubMed

Recknagel, Sebastian; Radant, Hendrik; Kohlmeyer, Regina

2014-01-01

The objective of this work was to provide updated information on the development of the potential impact of heavy metal containing batteries on municipal waste and battery recycling processes following transposition of the new EU Batteries Directive 2006/66/EC. A representative sample of 146 different types of commercially available dry and button cells as well as lithium-ion accumulators for mobile phones were analysed for their mercury (Hg)-, cadmium (Cd)- and lead (Pb)-contents. The methods used for preparing the cells and analysing the heavy metals Hg, Cd, and Pb were either developed during a former study or newly developed. Several batteries contained higher mass fractions of mercury or cadmium than the EU limits. Only half of the batteries with mercury and/or lead fractions above the marking thresholds were labelled. Alkaline-manganese mono-cells and Li-ion accumulators, on average, contained the lowest heavy metal concentrations, while zinc-carbon batteries, on average, contained the highest levels. Copyright © 2013 Elsevier Ltd. All rights reserved.

BOREAS TGB-12 Rn-222 Activity Data over the NSA

NASA Technical Reports Server (NTRS)

Trumbore, Susan; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor); Sundquist, Eric; Winston, Greg

2000-01-01

The BOREAS TGB-12 team made measurements of soil carbon inventories, carbon concentration in soil gases, and rates of soil respiration at several sites to estimate the rates of carbon accumulation and turnover in each of the major vegetation types. Sampling strategies for soils were designed to take advantage of local fire chronosequences, so that the accumulation of carbon in regrowing mosses could be determined. All the data are used to: (1) calculate the inventory of carbon and nitrogen in moss and mineral soil layers at NSA sites, (2) determine the rates of input and turnover (using both accumulation since the last stand-killing fire and radiocarbon data), and (3) link changes in soil respiration rate to shifts in the C-14 content of soil CO2 to determine the average "age" respired CO2 . These Rn-222 activity data were collected from 15-Nov-1993 to 16-Aug-1994 over the NSA sites. They are useful for determining the rate of gas exchange between soil and the overlying atmosphere. The data in this data set are stored in tabular ASCII files.

Carbon on Mercury's Surface - Origin, Distribution, and Concentration

NASA Technical Reports Server (NTRS)

Klima, Rachel L.; Blewett, David T.; Denevi, Brett W.; Ernst, Carolyn M.; Murchie, Scott L.; Peplowski, Patrick N.; Perera, Virange; Vander Kaaden, Kathleen

2018-01-01

Distinctive low-reflectance material (LRM) was first observed on Mercury in Mariner 10 flyby images. Visible to near-infrared reflectance spectra of LRM are flatter than the average reflectance spectrum of Mercury, which is strongly red sloped (increasing in reflectance with wavelength). From Mariner 10 and early MErcury, Surface, Space, ENvironment, GEochemistry, and Ranging (MESSENGER) flyby observations, it was suggested that a higher content of ilmenite, ulvospinel, carbon, or iron metal could cause both the characteristic dark, flat spectrum of LRM and the globally low reflectance of Mercury. Once MESSENGER entered orbit, low Fe and Ti abundances measured by the X-Ray and Gamma-Ray Spectrometers ruled out ilmenite, and ulvospinel as important surface constituents and implied that LRM was darkened by a different phase, such as carbon or small amounts of micro- or nanophase iron or iron sulfide dispersed in a silicate matrix. Low-altitude thermal neutron measurements of three LRM-rich regions confirmed an enhancement of 1-3 weight-percent carbon over the global abundance, supporting the hypothesis that LRM is darkened by carbon.

Organic carbon burial in a mangrove forest, margin and intertidal mud flat

NASA Astrophysics Data System (ADS)

Sanders, Christian J.; Smoak, Joseph M.; Naidu, A. Sathy; Sanders, Luciana M.; Patchineelam, Sambasiva R.

2010-12-01

The flux of total organic carbon (TOC) to depositional facies (intertidal mud flat, margin and forest) was quantified for a tropical mangrove forest in Brazil. Results indicate that these mangrove margins and intertidal mudflats are sites of large TOC accumulation, almost four times greater than the global averages for mangrove forests. The TOC burial rates were determined from organic carbon content in sediment cores which were dated using 210Pb. Burial rates were calculated to be 1129, 949, and 353 (g m -2 yr -1), for the mud flat, margin and forest, respectively. Sediment accumulation rates (SAR) were estimated to be 7.3, 5.0 and 2.8 mm yr -1. Sediment characterization (δ 13C, δ 15N, TOC/TN and mud fraction) indicated a representative mangrove system with a record of consistent organic matter flux of up to 100 years. Because of substantial burial of organic carbon in mangrove ecosystems, their role in the global carbon budget must be considered. More importantly, as climate change influences temperature and sea level, mangrove ecosystems will respond to specific climatic conditions.

Soil pyrogenic carbon lacks long-term persistence

NASA Astrophysics Data System (ADS)

Lutfalla, Suzanne; Abiven, Samuel; Barré, Pierre; Wiedemeier, Daniel; Christensen, Bent; Houot, Sabine; Kätterer, Thomas; Macdonald, Andy; van Oort, Fok; Chenu, Claire

2015-04-01

In the context of climate change, one mitigation technique currently investigated is the use of pyrogenic organic carbon (PyOC) -which is biomass turned into charcoal- to sequester carbon in soils with the hypothesis that PyOC is persistent and will not be biodegraded (or mineralized). In this study, we use the unique opportunity offered by five long term bare fallow (LTBF) experiments across Europe (Askov in Denmark, Grignon and Versailles in France, Ultuna in Sweden and Rothamsted in the United Kingdom) to compare the dynamics of PyOC and soil organic carbon (SOC) in the same plots at the decadal time scale (from 25 to 80 years of bare fallow depending on the site). Bare fallow plots were regularly sampled throughout the bare fallow duration and these samples were carefully archived. In bare fallow plots, with negligible external carbon input and with continuing biodegradation, SOC is depleting. Using the Benzene Polycarboxylic Acid (BPCA) technique to estimate the PyOC quantity and quality in the soils at different sampling dates, we investigated if PyOC content was also decreasing and compared the rates of depletion of PyOC and SOC. We found that PyOC contents decreased rapidly in soils at all sites. The loss of PyOC between the first and the last soil sampling ranged from 19.8 to 57.3% of the initial PyOC content. Furthermore, PyOC quality exhibited a similar evolution at all sites, becoming more enriched in condensed material with time. We applied a one pool model with mono-exponential decay to our data and found an average mean residence time of native PyOC of 116 years across the different sites, with a standard deviation of 15 years, just 1.6 times longer than that of SOC. Our results show that, though having a longer residence time than total SOC, PyOC content can decrease rapidly in soils suggesting that the potential for long-term C storage in soil by PyOC amendments is less than currently anticipated. Our results therefore question the concept of biochar production as a climate change mitigation strategy.

Perturbations in the carbon budget of the tropics

PubMed Central

Grace, John; Mitchard, Edward; Gloor, Emanuel

2014-01-01

The carbon budget of the tropics has been perturbed as a result of human influences. Here, we attempt to construct a ‘bottom-up’ analysis of the biological components of the budget as they are affected by human activities. There are major uncertainties in the extent and carbon content of different vegetation types, the rates of land-use change and forest degradation, but recent developments in satellite remote sensing have gone far towards reducing these uncertainties. Stocks of carbon as biomass in tropical forests and woodlands add up to 271 ± 16 Pg with an even greater quantity of carbon as soil organic matter. Carbon loss from deforestation, degradation, harvesting and peat fires is estimated as 2.01 ± 1.1 Pg annum−1; while carbon gain from forest and woodland growth is 1.85 ± 0.09 Pg annum−1. We conclude that tropical lands are on average a small carbon source to the atmosphere, a result that is consistent with the ‘top-down’ result from measurements in the atmosphere. If they were to be conserved, they would be a substantial carbon sink. Release of carbon as carbon dioxide from fossil fuel burning in the tropics is 0.74 Pg annum−1 or 0.57 MgC person−1 annum−1, much lower than the corresponding figures from developed regions of the world. PMID:24902948

[Effects of fertilizing regime and planting age on soil calcium decline in Luochuan apple orchards].

PubMed

Li, Peng; Li, Chun Yue; Wang, Yi Quan; Jiao, Cai Qiang

2017-05-18

This study was conducted to assess the effects of fertilizing regime and orchard planting age on soil calcium contents and stocks in the apple orchards on the Loess Plateau. The apple orchards in Luochuan County, one of the best regions for apple plantation in the world, were selec-ted in this study. The contents of calcium carbonate,water-soluble calcium and exchangeable cal-cium at 0-100 cm soil layer under different fertilizing regimes and various planting ages were mea-sured, their stocks were calculated and their variation features were analyzed. The results showed that soil in the apple orchards in the study region was characterized by the decline in calcium contents. The decline was more serious in apple orchards with long-term application of chemical fertili-zer than in those with combined application of chemical fertilizer and farmyard manure. The average contents of calcium carbonate, water-soluble calcium and exchangeable calcium at 0-100 cm soil layer in apple orchards with long-term application of chemical fertilizer decreased by 38.8%, 25.4% and 5.6% respectively than those in the apple orchards with long-term application of both chemical fertilizer and farmyard manure. The stocks of calcium carbonate, water-soluble calcium and exchangeable calcium decreased by 36.4%, 26.0% and 4.3%, respectively. The decline of soil cal-cium was aggravated with the increase of orchard planting age. The contents of calcium carbonate, water-soluble calcium and exchangeable calcium at 0-100 cm soil layer in orchards of more than 25 years of planting age decreased by 48.8%, 69.4% and 39.5% respectively, compared with orchards of less than 10 years of planting age, and the stocks decreased by 40.8%, 64.1% and 33.0%, respectively. These results indicated that either long-term application of chemical fertilizer or long-term plantation of apple trees obviously depleted soil calcium carbonate, water-soluble calcium and exchangeable calcium. Therefore, it was recommended that application of chemical fertilizer and farmyard manure should be combined to mitigate soil calcium decline, and calcium management should be strengthened in apple orchards of more than 25 years of planting age. The fertilizing regime was a driving factor of soil calcium decline which had a significant temporal (orchard planting age) and spatial (soil depth) effect.

The interaction between land use change, sediment fluxes and carbon dynamics: evaluating an integrated soil-landscape model at the millennial time-scale.

NASA Astrophysics Data System (ADS)

Bouchoms, Samuel; Van Oost, Kristof; Vanacker, Veerle

2015-04-01

Soil-landscape modelling has received growing attention as it allows us to evaluate the interaction between earth surface and soil bio-physical processes. At the landscape scale, human-induced land use change has altered the balance between soil erosion and production, and largely modified sediment fluxes. Intensification in soil redistribution rates affects the interaction between soil chemical, physical and biological processes at the landscape scale. Here, we evaluate the SPEROS-LT model, a spatially explicit 3D model combining a dynamic representation of land use, soil erosion and deposition and the soil carbon cycle. We assess the impact of millennial-scale human-induced land use change on sediment fluxes and carbon dynamics in the Dijle catchement (central Belgium). The watershed has undergone a 3000 years continuous human-induced alteration of the vegetation covers for agricultural characterized by Our study is based on land use reconstructions for the last 3000 years, including massive deforestation for agriculture in Roman Times and the Middle Ages followed by urbanization in the last 150 years. Land use reconstructions rely on simple land use allocation rules based on slope gradients. SPEROS-LT is parametrized for erosion rates against available figures in the literature by changing the transport capacity and the transfer coefficient which defines the amount of flux transferred between different land uses. Carbon content profiles at steady state (i.e. without influence of erosion or deposition) are calibrated for each land use and for the first upper meter of soil by comparing modeled profiles to an averaged observed profiles in stable areas of the pedologic region. We present a model sensitivity analysis and a full validation of the predicted soil carbon storage (horizontally, i.e. in space, and vertically, i.e. with depth) using a large database of observational data. The results indicate (i) a good agreement of the erosion rates. Speros LT modeled erosion and export rates, both modern and averaged over the last millennium, fall into the published range. Mean erosion rate over the last 1000 years equals 4.6 t/ha over the entire catchment while the export rate is 1.2 t/ha. (ii) Carbon content in the erosion areas is well predicted for lower soil layers (from 20 to 80 cm) where no significant differences were found between observational and modeled C content. There is though a significant difference for the top soil where modeled mean is 0.92% compared to the 0.8% in observations. (iii) erosion and deposition's spatial patterns are relatively well represented: correspondence between erosion areas as extracted from the digital soil map and modeled erosion maps higher for slightly truncated areas than in high truncation areas (55% of the modeled erosions pixels correspond to a non-depositional area compared to 37%). Correspondence between the model and the soil map increases with the total deposition ranging from 19% to 30% Yet, the model overestimated the carbon content in depositional areas, where statistical differences between observed and modeled carbon amount were found for each soil layers. This indicates that other factors, not accounted for by the model, influence carbon turnover for these sites. They may have a different dynamic than eroding places, cycling carbon faster or transferring it quicker to higher depth. Overall, the results indicates that the model performs relatively well in predicting sediment fluxes and carbon amount on long time scale during transient simulation. They underline the importance of developing an integrated approach to understand the dynamic and interactions at the landscape scale.

Soil organic carbon pools and stocks in permafrost-affected soils on the tibetan plateau.

PubMed

Dörfer, Corina; Kühn, Peter; Baumann, Frank; He, Jin-Sheng; Scholten, Thomas

2013-01-01

The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA) and continuous permafrost (site Wudaoliang, WUD). Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (<1.6 g cm(-3)) of free particulate organic matter (FPOM) and occluded particulate organic matter (OPOM), plus a heavy fraction (>1.6 g cm(-3)) of mineral associated organic matter (MOM). The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg(-1). Higher SOC contents (320 g kg(-1)) were found in OPOM while MOM had the lowest SOC contents (29 g kg(-1)). Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA) and 22% (WUD) to the total SOC stocks. In HUA mean SOC stocks (0-30 cm depth) account for 10.4 kg m(-2), compared to 3.4 kg m(-2) in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation.

Organic geochemistry of sediments of the Deep Gulf of Mexico Basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sassen, R.; Fang Jiasong

1990-05-01

Analysis of 716 core samples cored at DSDP (Deep Sea Drilling Project) Leg 96 in the Mississippi submarine fan and the Orca and Pigmy basins in the Louisiana continental slope using a Rock-Eval pyrolysis unit with a TOC (total organic carbon) module allows computations of hydrogen index (HI), total organic carbon, kerogen type, and oil generative capacity assessment. No samples are obviously oil prone. TOC content ranges from 0.12 to 2.29%, with an overall average of 9.82%. HI values are generally less than 150 mg HC/g TOC. T{sub max} (maximum temperature of S{sub 2}) values (average = 425{degree}C) show themore » sediments are thermally immature through-out the study area. Hydrocarbon generative potential of the sediments ranges from 492 to 1,107 ppm, with an average of 854 ppm. Higher PI (Production index) values, ranging from 0.12 to 0.32 and averaging 0.15, suggest the presence of hydrocarbon seepage. Because of organically lean, thermally immature, and gas-prone terrestrial kerogen, there is little reason to assume that the sediments of the Mississippi fan can provide oil source rock for the Gulf of Mexico Basin, or that sediments of anoxic basins in the Louisiana continental slope are analogs to past environments where source rocks for crude oil have been deposited.« less

Tensile Fracture Behavior of 316L Austenitic Stainless Steel Manufactured by Hot Isostatic Pressing

NASA Astrophysics Data System (ADS)

Cooper, A. J.; Brayshaw, W. J.; Sherry, A. H.

2018-02-01

Herein we investigate how the oxygen content in hot isostatically pressed (HIP'd) 316L stainless steel affects the mechanical properties and tensile fracture behavior. This work follows on from previous studies, which aimed to understand the effect of oxygen content on the Charpy impact toughness of HIP'd steel. We expand on the work by performing room-temperature tensile testing on different heats of 316L stainless steel, which contain different levels of interstitial elements (carbon and nitrogen) as well as oxygen in the bulk material. Throughout the work we repeat the experiments on conventionally forged 316L steel as a reference material. The analysis of the work indicates that oxygen does not contribute to a measureable solution strengthening mechanism, as is the case with carbon and nitrogen in austenitic stainless steels (Werner in Mater Sci Eng A 101:93-98, 1988). Neither does oxygen, in the form of oxide inclusions, contribute to precipitation hardening due to the size and spacing of particles. However, the oxide particles do influence fracture behavior; fractography of the failed tension test specimens indicates that the average ductile dimple size is related to the oxygen content in the bulk material, the results of which support an on-going hypothesis relating oxygen content in HIP'd steels to their fracture mechanisms by providing additional sites for the initiation of ductile damage in the form of voids.

Full-Scale Test Program for a Shower Wastewater Recycling System: Technical Evaluation

DTIC Science & Technology

1987-01-01

taken, each using sn average 10.6 gal of water. Hathers were permitted to use their own choice of soap and shampoo , a condition expected to exist in a...Laboratories in Richmond, VA, using a Beckman Total Organic Carbon Analyzer, Model 915. Sulfate The Hach SulfaVer 4 Sulfate Reagent was used to measure... sulfate content by the turbidimetric metal.. Turbidity A Hach Laboratory Turbidimeter, Model 2100A, was used to measure turbidity. pH A Photovolt pH meter

Concentration effect on inter-mineral equilibrium isotope fractionation: insights from Mg and Ca isotopic systems

NASA Astrophysics Data System (ADS)

Huang, F.; Wang, W.; Zhou, C.; Kang, J.; Wu, Z.

2017-12-01

Many naturally occurring minerals, such as carbonate, garnet, pyroxene, and feldspar, are solid solutions with large variations in chemical compositions. Such variations may affect mineral structures and modify the chemical bonding environment around atoms, which further impacts the equilibrium isotope fractionation factors among minerals. Here we investigated the effects of Mg content on equilibrium Mg and Ca isotope fractionation among carbonates and Ca content on equilibrium Ca isotope fractionation between orthopyroxene (opx) and clinopyroxene (cpx) using first-principles calculations. Our results show that the average Mg-O bond length increases with decreasing Mg/(Mg+Ca) in calcite when it is greater than 1/48[1] and the average Ca-O bond length significantly decreases with decreasing Ca/(Ca+Mg+Fe) in opx when it ranges from 2/16 to 1/48[2]. Equilibrium isotope fractionation is mainly controlled by bond strengths, which could be measured by bond lengths. Thus, 103lnα26Mg/24Mg between dolomite and calcite dramatically increases with decreasing Mg/(Mg+Ca) in calcite [1] and it reaches a constant value when it is lower than 1/48. 103lnα44Ca/40Ca between opx and cpx significantly increases with decreasing Ca content in opx when Ca/(Ca+Mg+Fe) ranges from 2/16 to 1/48 [2]. If Ca/(Ca+Mg+Fe) is below 1/48, 103lnα44Ca/40Ca is not sensitive to Ca content. Based on our results, we conclude that the concentration effect on equilibrium isotope fractionation could be significant within a certain range of chemical composition of minerals, which should be a ubiquitous phenomenon in solid solution systems. [1] Wang, W., Qin, T., Zhou, C., Huang, S., Wu, Z., Huang, F., 2017. GCA 208, 185-197. [2] Feng, C., Qin, T., Huang, S., Wu, Z., Huang, F., 2014. GCA 143, 132-142.

Solute concentrations influence microbial methanogenesis in coal-bearing strata of the Cherokee basin, USA

DOE PAGES

Kirk, Matthew F.; Wilson, Brien H.; Marquart, Kyle A.; ...

2015-11-18

In this study, microorganisms have contributed significantly to subsurface energy resources by converting organic matter in hydrocarbon reservoirs into methane, the main component of natural gas. In this study, we consider environmental controls on microbial populations in coal-bearing strata of the Cherokee basin, an unconventional natural gas resource in southeast Kansas, USA. Pennsylvanian-age strata in the basin contain numerous thin (0.4–1.1 m) coalbeds with marginal thermal maturities (0.5–0.7% R o) that are interbedded with shale and sandstone. We collected gas, water, and microbe samples from 16 commercial coalbed methane wells for geochemical and microbiological analysis. The water samples were Na–Clmore » type with total dissolved solids (TDS) content ranging from 34.9 to 91.3 g L –1. Gas dryness values [C 1/(C 2 + C 3)] averaged 2640 and carbon and hydrogen isotope ratios of methane differed from those of carbon dioxide and water, respectively, by an average of 65 and 183‰. These values are thought to be consistent with gas that formed primarily by hydrogenotrophic methanogenesis. Results from cultivation assays and taxonomic analysis of 16S rRNA genes agree with the geochemical results. Cultivable methanogens were present in every sample tested, methanogen sequences dominate the archaeal community in each sample (avg 91%), and few archaeal sequences (avg 4.2%) were classified within Methanosarcinales, an order of methanogens known to contain methylotrophic methanogens. Although hydrogenotrophs appear dominant, geochemical and microbial analyses both indicate that the proportion of methane generated by acetoclastic methanogens increases with the solute content of formation water, a trend that is contrary to existing conceptual models. Consistent with this trend, beta diversity analyses show that archaeal diversity significantly correlates with formation water solute content. In contrast, bacterial diversity more strongly correlates with location than solute content, possibly as a result of spatial variation in the thermal maturity of the coalbeds.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirk, Matthew F.; Wilson, Brien H.; Marquart, Kyle A.

In this study, microorganisms have contributed significantly to subsurface energy resources by converting organic matter in hydrocarbon reservoirs into methane, the main component of natural gas. In this study, we consider environmental controls on microbial populations in coal-bearing strata of the Cherokee basin, an unconventional natural gas resource in southeast Kansas, USA. Pennsylvanian-age strata in the basin contain numerous thin (0.4–1.1 m) coalbeds with marginal thermal maturities (0.5–0.7% R o) that are interbedded with shale and sandstone. We collected gas, water, and microbe samples from 16 commercial coalbed methane wells for geochemical and microbiological analysis. The water samples were Na–Clmore » type with total dissolved solids (TDS) content ranging from 34.9 to 91.3 g L –1. Gas dryness values [C 1/(C 2 + C 3)] averaged 2640 and carbon and hydrogen isotope ratios of methane differed from those of carbon dioxide and water, respectively, by an average of 65 and 183‰. These values are thought to be consistent with gas that formed primarily by hydrogenotrophic methanogenesis. Results from cultivation assays and taxonomic analysis of 16S rRNA genes agree with the geochemical results. Cultivable methanogens were present in every sample tested, methanogen sequences dominate the archaeal community in each sample (avg 91%), and few archaeal sequences (avg 4.2%) were classified within Methanosarcinales, an order of methanogens known to contain methylotrophic methanogens. Although hydrogenotrophs appear dominant, geochemical and microbial analyses both indicate that the proportion of methane generated by acetoclastic methanogens increases with the solute content of formation water, a trend that is contrary to existing conceptual models. Consistent with this trend, beta diversity analyses show that archaeal diversity significantly correlates with formation water solute content. In contrast, bacterial diversity more strongly correlates with location than solute content, possibly as a result of spatial variation in the thermal maturity of the coalbeds.« less

Organic carbon and nitrogen content associated with colloids and suspended particulates from the Mississippi River and some of its tributaries

USGS Publications Warehouse

Rostad, C.E.; Leenheer, J.A.; Daniel, S.R.

1997-01-01

Suspended material samples were collected at 16 sites along the Mississippi River and some of its tributaries during July-August 1991, October-November 1991, and April-May 1992, and separated into colloid and particulate fractions to determine the organic carbon content of these two fractions of suspended material. Sample collection involved centrifugation to isolate the suspended particulate fraction and ultrafiltration to isolate the colloid fraction. For the first time, particulate and colloid concentrations and organic carbon and nitrogen content were investigated along the entire reach of the Mississippi River from above Minneapolis, Minnesota, to below New Orleans, Louisiana. Organic carbon content of the colloid (15.2 percent) was much higher than organic carbon content of the particulate material (4.8 percent). Carbon/nitrogen ratios of colloid and particulate phases were more similar to ratios for microorganisms than to ratios for soils, humic materials, or plants.Suspended material samples were collected at 16 sites along the Mississippi River and some of its tributaries during July-August 1991, October-November 1991, and April-May 1992, and separated into colloid and particulate fractions to determine the organic carbon content of these two fractions of suspended material. Sample collection involved centrifugation to isolate the suspended particulate fraction and ultrafiltration to isolate the colloid fraction. For the first time, particulate and colloid concentrations and organic carbon and nitrogen content were investigated along the entire reach of the Mississippi River from above Minneapolis, Minnesota, to below New Orleans, Louisiana. Organic carbon content of the colloid (15.2 percent) was much higher than organic carbon content of the particulate material (4.8 percent). Carbon/nitrogen ratios of colloid and particulate phases were more similar to ratios for microorganisms than to ratios for soils, humic materials, or plants.

[Effects of arbuscular mycorrhizal fungi on root system morphology and sucrose and glucose contents of Poncirus trifoliata].

PubMed

Zou, Ying-Ning; Wu, Qiang-Sheng; Li, Yan; Huang, Yong-Ming

2014-04-01

The effects of inoculation with Glomus mosseae, G. versiforme, and their mixture on plant growth, root system morphology, and sucrose and glucose contents of trifoliate orange (Poncirus trifoliata L.) were studied by pot culture. The results showed that all the inoculated treatments significantly increased the plant height, stem diameter, leaf number, and shoot and root biomass. In addition, the mycorrhizal treatments significantly increased the number of 1st, 2nd, and 3rd lateral roots. Inoculation with arbuscular mycorrhizal fungi significantly increased the root projected area, surface area, volume, and total root length (mainly 0-1 cm root length), but decreased the root average diameter. Meanwhile, G. versiforme showed the best effects. Mycorrhizal inoculation significantly increased the leaf sucrose and root glucose contents, but decreased the leaf glucose and root sucrose contents. Owing to the 'mycorrhizal carbon pool' in roots, inoculation with arbuscular mycorrhizal fungi resulted in high glucose content and low sucrose content of roots, which would facilitate the root growth and development, thereby the establishment of better root system morphology of host plants.

Influence of moisture content and temperature on degree of carbonation and the effect on Cu and Cr leaching from incineration bottom ash.

PubMed

Lin, Wenlin Yvonne; Heng, Kim Soon; Sun, Xiaolong; Wang, Jing-Yuan

2015-09-01

This study investigated the influence of moisture content and temperature on the degree of carbonation of municipal solid waste (MSW) incineration bottom ash (IBA) from two different incineration plants in Singapore. The initial rate of carbonation was affected by the nominal moisture content used. Carbonation temperature seemed to play a part in changing the actual moisture content of IBA during carbonation, which in turn affected the degree of carbonation. Results showed that 2h of carbonation was sufficient for the samples to reach a relatively high degree of carbonation that was close to the degree of carbonation observed after 1week of carbonation. Both Cu and Cr leaching also showed significant reduction after only 2h of carbonation. Therefore, the optimum moisture content and temperature were selected based on 2h of carbonation. The optimum moisture content was 15% for both incineration plants while the optimum temperature was different for the two incineration plants, at 35°C and 50°C. The effect on Cu and Cr leaching from IBA after accelerated carbonation was evaluated as a function of carbonation time. Correlation coefficient, Pearson's R, was used to determine the dominant leaching mechanism. The reduction in Cu leaching was found to be contributed by both formation of carbonate mineral and reduction of DOC leaching. On the other hand, Cr leaching seemed to be dominantly controlled by pH. Copyright © 2015 Elsevier Ltd. All rights reserved.

Carbon and greenhouse gas balance of the FR-GRI crop site from 2005 to 2014

NASA Astrophysics Data System (ADS)

Loubet, Benjamin; Chammakhi, Manel; Mascher, Nicolas; Durand, Brigitte; Gueudet, Jean-Christophe; Decuq, Céline; Lecuyer, Vanessa; Laville, Patricia; Buysse, Pauline; Cellier, Pierre

2017-04-01

The carbon and greenhouse gas balance of the ICOS FR-GRI site from 2005 to 2014 is presented. The site is a wheat-barley-maize rotation with the introduction of oil-seed rape in 2012. The site receives large amounts of organic fertilization, but is shown to be a strong source of carbon to the atmosphere, especially due to the increase in the exportations of residues during the period. The exportations have increased from around 4 to around 8 t C ha-1 year-1 over the period on average except for maize for which it remained constant. In the meantime the carbon importations have increased from around 1 to around 2 t C ha-1 year-1 during the same period. Overall the field was losing around 2 t C ha-1 year-1 over the whole period but largely driven by last years (2012-2014). This would represent 17% loss of the soil carbon content in the 0-60 cm in the 2005-2014 period. The discussion focuses on explanations of these losses and possible drawbacks in the methodology. The effect of the winter intermediate crops on the carbon balance is also discussed.

Organic / inorganic carbon content and isotope analysis of 3.1Ga Cleaverville Formation in Pilbara, Australia: Result of DXCL project

NASA Astrophysics Data System (ADS)

Miki, T.; Kiyokawa, S.; Ito, T.; Yamaguchi, K. E.; Ikehara, M.

2014-12-01

DXCL project was targeted for 3.2-3.1 Ga hydrothermal chert-black shale (Dixon Island Formation) and black shale-banded iron formation (Cleaverville Formation). CL3 core (200m long) was drilled from 1) upper part of Black Shale Member (35m thick) to 2) lower part of BIF Member (165m thick) of the Cleaverville Formation. Here, the BIF Member can be divided into three submembers; Greenish shale-siderite (50m thick), Magnetite-siderite (55m thick) and Black shale-siderite (60m) submembers. In this study, we used bulk samples and samples treated by hot hydrochloric acid in order to extract organic carbon. 　The Black shale Member consists of black carbonaceous　matter and fine grain quartz (< 100μm). Organic carbon content (Corg) of black shale is 1.2% in average and organic carbon isotope ratio (δ13Corg) is -31.4 to -28.7‰. On the other hand, inorganic carbon isotope ratio of siderite (δ13Ccarb) was -5.2 to +12.6‰. 　In the BIF Member, the Greenish shale-siderite submember is composed of well laminated greenish sideritic shale and white chert (<7mm thick), which is gradually increase from black shale of the Black shale Member through about 10m. Magnetite-siderite submember contains very fine magnetite lamination with inter-bedded greenish sideritic shale and siderite lamination. Hematite is identified near fractured part. The Black shale-siderite submember is composed of black shale, siderite and chert bands. 　1) Siderite layers of these three submembers showedδ13Ccarb value of -14.6 to -3.8‰. Corg and δ13Corg content are 0.2% and -18.3 to -0.3‰. 2) Siderite grains within greenish sideritic shales showedδ13Ccarb value of -12.9 to +15.0‰. 3) Black shale of Corg and δ13Corg content in the BIF Member are 0.1% and -36.3 to -17.1‰ respectively. 　We found great difference in values of δ13Ccarb of siderite. One is Corg-rich shale (up to +15.0‰) and the other is Corg-poor siderite layers (up to -3.8‰). The lighter value of siderite layers may be originated from precursor organic carbon which is strongly affected by biological activity.

Comparison of the carbon stock in forest soil of sessile oak and beech forests

NASA Astrophysics Data System (ADS)

Horváth, Adrienn; Bene, Zsolt; Bidló, András

2016-04-01

Forest ecosystems are the most important carbon sinks. The forest soils play an important role in the global carbon cycle, because the global climate change or the increase of atmospheric CO2 level. We do not have enough data about the carbon stock of soils and its change due to human activities, which have similar value to carbon content of biomass. In our investigation we measured the carbon stock of soil in 10 stands of Quercus petraea and Fagus sylvatica. We took a 1.1 m soil column with soil borer and divided to 11 samples each column. The course organic and root residues were moved. After evaluation, we compared our results with other studies and the carbon stock of forests to each other. Naturally, the amount of SOC was the highest in the topsoil layers. However, we found significant difference between forest stands which stayed on the same homogenous bedrock, but very close to each other (e.g. distance was 1 or 2 km). We detected that different forest utilizations and tree species have an effect on the forest carbon as the litter as well (amount, composition). In summary, we found larger amount (99.1 C t/ha on average) of SOC in soil of stands, where sessile oak were the main stand-forming tree species. The amount of carbon was the least in turkey oak-sessile oak stands (85.4 C t/ha on average). We found the highest SOC (118.3 C t/ha) in the most mixed stand (silver lime-beech-red oak). In the future, it will be very important: How does climate change affect the spread of tree species or on carbon storage? Beech is more sensitive, but even sessile oak. These species are expected to replace with turkey oak, which is less sensitive to drought. Thus, it is possible in the future that we can expect to decrease of forest soil carbon stock capacity, which was confirmed by our experiment. Keywords: carbon sequestration, mitigation, Fagus sylvatica, Quercus petraea, litter Acknowledgements: Research is supported by the "Agroclimate.2" (VKSZ_12-1-2013-0034) EU-national joint funded research project.

Nitrogen and carbon isotopic dynamics of subarctic soils and plants in southern Yukon Territory and its implications for paleoecological and paleodietary studies

PubMed Central

Longstaffe, Fred J.; Zazula, Grant; Bennett, Bruce

2017-01-01

We examine here the carbon and nitrogen isotopic compositions of bulk soils (8 topsoil and 7 subsoils, including two soil profiles) and five different plant parts of 79 C3 plants from two main functional groups: herbs and shrubs/subshrubs, from 18 different locations in grasslands of southern Yukon Territory, Canada (eastern shoreline of Kluane Lake and Whitehorse area). The Kluane Lake region in particular has been identified previously as an analogue for Late Pleistocene eastern Beringia. All topsoils have higher average total nitrogen δ15N and organic carbon δ13C than plants from the same sites with a positive shift occurring with depth in two soil profiles analyzed. All plants analyzed have an average whole plant δ13C of −27.5 ± 1.2 ‰ and foliar δ13C of –28.0 ± 1.3 ‰, and average whole plant δ15N of −0.3 ± 2.2 ‰ and foliar δ15N of –0.6 ± 2.7 ‰. Plants analyzed here showed relatively smaller variability in δ13C than δ15N. Their average δ13C after suitable corrections for the Suess effect should be suitable as baseline for interpreting diets of Late Pleistocene herbivores that lived in eastern Beringia. Water availability, nitrogen availability, spacial differences and intra-plant variability are important controls on δ15N of herbaceous plants in the study area. The wider range of δ15N, the more numerous factors that affect nitrogen isotopic composition and their likely differences in the past, however, limit use of the modern N isotopic baseline for vegetation in paleodietary models for such ecosystems. That said, the positive correlation between foliar δ15N and N content shown for the modern plants could support use of plant δ15N as an index for plant N content and therefore forage quality. The modern N isotopic baseline cannot be applied directly to the past, but it is prerequisite to future efforts to detect shifts in N cycling and forage quality since the Late Pleistocene through comparison with fossil plants from the same region. PMID:28813532

[Profile distribution of soil aggregates organic carbon in primary forests in Karst cluster-peak depression region].

PubMed

Lu, Ling-Xiao; Song, Tong-Qing; Peng, Wan-Xia; Zeng, Fu-Ping; Wang, Ke-Lin; Xu, Yun-Lei; Yu, Zi; Liu, Yan

2012-05-01

Soil profiles were collected from three primary forests (Itoa orientalis, Platycladus orientalis, and Radermachera sinica) in Karst cluster-peak depression region to study the composition of soil aggregates, their organic carbon contents, and the profile distribution of the organic carbon. In the three forests, >2 mm soil aggregates were dominant, occupying about 76% of the total. The content of soil total organic carbon ranged from 12.73 to 68.66 g x kg(-1), with a significant difference among the forests. The organic carbon content in <1 mm soil aggregates was slightly higher than that in >2 mm soil aggregates, but most of soil organic carbon was stored in the soil aggregates with greater particle sizes. About 70% of soil organic carbon came from >2 mm soil aggregates. There was a significant positive relationship between the contents of 2-5 and 5-8 mm soil aggregates and the content of soil organic carbon. To increase the contents of 2-8 mm soil aggregates could effectively improve the soil carbon sequestration in Karst region. In Itoa orientalis forest, 2-8 mm soil aggregates accounted for 46% of the total, and the content of soil total organic carbon reached to 37.62 g x kg(-1), which implied that Itoa orientalis could be the suitable tree species for the ecological restoration in Karst region.

Vehicle emissions and consumer information in car advertisements

PubMed Central

Wilson, Nick; Maher, Anthony; Thomson, George; Keall, Michael

2008-01-01

Background The advertising of vehicles has been studied from a safety perspective but not in terms of vehicle air pollutants. We aimed to examine the content and trends of greenhouse gas emissions and air pollution-related information, in light passenger vehicle advertisements. Methods Content analysis of the two most popular current affairs magazines in New Zealand for the five year period 2001–2005 was undertaken (n = 514 advertisements). This was supplemented with vehicle data from official websites. Results The advertisements studied provided some information on fuel type (52%), and engine size (39%); but hardly any provided information on fuel efficiency (3%), or emissions (4%). Over the five-year period the reported engine size increased significantly, while fuel efficiency did not improve. For the vehicles advertised, for which relevant official website data could be obtained, the average "greenhouse rating" for carbon dioxide (CO2) emissions was 5.1, with a range from 0.5 to 8.5 (on a scale with 10 being the best and 0.5 being the most polluting). The average CO2 emissions were 50% higher than the average for cars made by European manufacturers. The average "air pollution" rating for the advertised vehicles was 5.4 (on the same 1–10 scale). The yearly averages for the "greenhouse" or "air pollution" ratings did not change significantly over the five-year period. One advertised hybrid vehicle had a fuel consumption that was under half the average (4.4 versus 9.9 L/100 km), as well as the best "greenhouse" and "air pollution" ratings. Conclusion To enhance informed consumer choice and to control greenhouse gas and air pollution emissions, governments should introduce regulations on the content of vehicle advertisements and marketing (as started by the European Union). Similar regulations are already in place for the marketing of many other consumer products. PMID:18445291

Influence of carbon content on photocatalytic performance of C@ZnO hollow nanospheres

NASA Astrophysics Data System (ADS)

Jin, Changqing; Zhu, Kexin; Jian, Zengyun; Wei, Yongxing; Gao, Ling; Zhang, Zhihong; Zheng, Deshan

2018-02-01

Mesoporous C@ZnO hollow spheres were successfully synthesized through a carbon-sphere template combined hydrothermal method. The photocatalytic activities of the samples to rhodamine B (RhB) were investigated, and the sample of 3 wt% carbon has the best photocatalytic activity to RhB. The excellent photocatalytic performance could come from both enhanced photogenerated electron-hole pair separation, and the larger specific surface area induced by mesoporous hollow nanostructure. The photocatalytic performance sensitively depends upon content of amorphous carbon. Too much or too little carbon content decreases sample performance. The changes in performance according to carbon content are probably a result of the competing mechanism: the increasing rate of separation efficiency of photogenerated carriers and the decreasing contact area of ZnO with RhB according to the carbon content. This work would help us to better understand the important roles of carbon content in the fabricated nano-heterojunctions and also provide us with a feasible route to improve UV photocatalytic activities of ZnO and other metal oxides greatly.

Carbon losses from all soils across England and Wales 1978-2003.

PubMed

Bellamy, Pat H; Loveland, Peter J; Bradley, R Ian; Lark, R Murray; Kirk, Guy J D

2005-09-08

More than twice as much carbon is held in soils as in vegetation or the atmosphere, and changes in soil carbon content can have a large effect on the global carbon budget. The possibility that climate change is being reinforced by increased carbon dioxide emissions from soils owing to rising temperature is the subject of a continuing debate. But evidence for the suggested feedback mechanism has to date come solely from small-scale laboratory and field experiments and modelling studies. Here we use data from the National Soil Inventory of England and Wales obtained between 1978 and 2003 to show that carbon was lost from soils across England and Wales over the survey period at a mean rate of 0.6% yr(-1) (relative to the existing soil carbon content). We find that the relative rate of carbon loss increased with soil carbon content and was more than 2% yr(-1) in soils with carbon contents greater than 100 g kg(-1). The relationship between rate of carbon loss and carbon content is irrespective of land use, suggesting a link to climate change. Our findings indicate that losses of soil carbon in England and Wales--and by inference in other temperate regions-are likely to have been offsetting absorption of carbon by terrestrial sinks.

Changes in Soil Carbon Following Afforestation

DOE Data Explorer

Paul, K. I. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Kingston ACT (Australia); Polglase, P. J. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Kingston ACT (Australia; Nyakuengama, J. G. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Kingston ACT (Australia); Khanna, P. K. [Commonwealth Scientific and Industrial Research Organization (CSIRO), Kingston ACT (Australia)

2003-01-01

Quantifying changes in soil C may be an important consideration under large-scale afforestation or reforestation. We reviewed global data on changes in soil C following afforestation, available from 43 published or unpublished studies, encompassing 204 sites. Data were highly variable, with soil C either increasing or decreasing, particularly in young (<10-y) forest stands. Because studies varied in the number of years since forest establishment and the initial soil C content, we calculated change in soil C as a weighted average (i.e. sum of C change divided by sum of years since forest establishment) relative to the soil C content under previous agricultural systems at <10 cm, >10 cm and <30 cm sampling depths. On average, soil C in the <10 cm (or <30 cm) layers generally decreased by 3.46% y^–1 (or 0.63% y^–1) relative to the initial soil C content during the first five years of afforestation, followed by a decrease in the rate of decline and eventually recovery to C contents found in agricultural soils at about age 30. In plantations older than 30 years, C content was similar to that under the previous agricultural systems within the surface 10 cm of soil, yet at other sampling depths, soil C had increased by between 0.50 and 0.86% y^–1. Amounts of C lost or gained by soil are generally small compared with accumulation of C in tree biomass.

Halogenated volatile organic compounds in chlorine-bleach-containing household products and implications for their use

NASA Astrophysics Data System (ADS)

Odabasi, Mustafa; Elbir, Tolga; Dumanoglu, Yetkin; Sofuoglu, Sait C.

2014-08-01

It was recently shown that substantial amounts of halogenated volatile organic compounds (VOCs) are formed in chlorine-bleach-containing household products as a result of reactions of sodium hypochlorite with organic product components. Use of these household products results in elevated indoor air halogenated VOC concentrations. Halogenated VOCs in several chlorine-bleach-containing household products (plain, n = 9; fragranced, n = 4; and surfactant-added, n = 29) from Europe and North America were measured in the present study. Chloroform and carbon tetrachloride were the dominating compounds having average concentrations of 9.5 ± 29.0 (average ± SD) and 23.2 ± 44.3 (average ± SD) mg L-1, respectively. Halogenated VOC concentrations were the lowest in plain bleach, slightly higher in fragranced products and the highest in the surfactant-added products. Investigation of the relationship between the halogenated VOCs and several product ingredients indicated that chlorinated VOC formation is closely related to product composition. Indoor air concentrations from the household use of bleach products (i.e., bathroom, kitchen, and hallway cleaning) were estimated for the two dominating VOCs (chloroform and carbon tetrachloride). Estimated indoor concentrations ranged between 0.5 and 1030 (34 ± 123, average ± SD) μg m-3 and 0.3-1124 (82 ± 194, average ± SD) μg m-3 for chloroform and carbon tetrachloride, respectively, indicating substantial increases compared to background. Results indicated that indoor air concentrations from surfactant-added products were significantly higher (p < 0.01) than other categories. The highest concentrations were from the use of surfactant-added bleach products for bathroom cleaning (92 ± 228 and 224 ± 334 μg m-3, average ± SD for chloroform and carbon tetrachloride, respectively). Associated carcinogenic risks from the use of these products were also estimated. The risk levels may reach to considerably high levels for a significant portion of the population especially for those steadily using the surfactant-added bleach products. Based on the results of the present study, it could be recommended that if possible the use of chlorine bleach containing household products should be avoided. If they are to be used, plain products should be preferred since the chlorinated VOC content increase with the number and amount of additives.

Sensitivity of Temperate Desert Steppe Carbon Exchange to Seasonal Droughts and Precipitation Variations in Inner Mongolia, China

PubMed Central

Yang, Fulin; Zhou, Guangsheng

2013-01-01

Arid grassland ecosystems have significant interannual variation in carbon exchange; however, it is unclear how environmental factors influence carbon exchange in different hydrological years. In this study, the eddy covariance technique was used to investigate the seasonal and interannual variability of CO2 flux over a temperate desert steppe in Inner Mongolia, China from 2008 to 2010. The amounts and times of precipitation varied significantly throughout the study period. The precipitation in 2009 (186.4 mm) was close to the long-term average (183.9±47.6 mm), while the precipitation in 2008 (136.3 mm) and 2010 (141.3 mm) was approximately a quarter below the long-term average. The temperate desert steppe showed carbon neutrality for atmospheric CO2 throughout the study period, with a net ecosystem carbon dioxide exchange (NEE) of −7.2, −22.9, and 26.0 g C m−2 yr−1 in 2008, 2009, and 2010, not significantly different from zero. The ecosystem gained more carbon in 2009 compared to other two relatively dry years, while there was significant difference in carbon uptake between 2008 and 2010, although both years recorded similar annual precipitation. The results suggest that summer precipitation is a key factor determining annual NEE. The apparent quantum yield and saturation value of NEE (NEEsat) and the temperature sensitivity coefficient of ecosystem respiration (Reco) exhibited significant variations. The values of NEEsat were −2.6, −2.9, and −1.4 µmol CO2 m−2 s−1 in 2008, 2009, and 2010, respectively. Drought suppressed both the gross primary production (GPP) and Reco, and the drought sensitivity of GPP was greater than that of Reco. The soil water content sensitivity of GPP was high during the dry year of 2008 with limited soil moisture availability. Our results suggest the carbon balance of this temperate desert steppe was not only sensitive to total annual precipitation, but also to its seasonal distribution. PMID:23393576

Sensitivity of temperate desert steppe carbon exchange to seasonal droughts and precipitation variations in Inner Mongolia, China.

PubMed

Yang, Fulin; Zhou, Guangsheng

2013-01-01

Arid grassland ecosystems have significant interannual variation in carbon exchange; however, it is unclear how environmental factors influence carbon exchange in different hydrological years. In this study, the eddy covariance technique was used to investigate the seasonal and interannual variability of CO₂ flux over a temperate desert steppe in Inner Mongolia, China from 2008 to 2010. The amounts and times of precipitation varied significantly throughout the study period. The precipitation in 2009 (186.4 mm) was close to the long-term average (183.9±47.6 mm), while the precipitation in 2008 (136.3 mm) and 2010 (141.3 mm) was approximately a quarter below the long-term average. The temperate desert steppe showed carbon neutrality for atmospheric CO₂ throughout the study period, with a net ecosystem carbon dioxide exchange (NEE) of -7.2, -22.9, and 26.0 g C m⁻² yr⁻¹ in 2008, 2009, and 2010, not significantly different from zero. The ecosystem gained more carbon in 2009 compared to other two relatively dry years, while there was significant difference in carbon uptake between 2008 and 2010, although both years recorded similar annual precipitation. The results suggest that summer precipitation is a key factor determining annual NEE. The apparent quantum yield and saturation value of NEE (NEE(sat)) and the temperature sensitivity coefficient of ecosystem respiration (R(eco)) exhibited significant variations. The values of NEE(sat) were -2.6, -2.9, and -1.4 µmol CO₂ m⁻² s⁻¹ in 2008, 2009, and 2010, respectively. Drought suppressed both the gross primary production (GPP) and R(eco), and the drought sensitivity of GPP was greater than that of R(eco). The soil water content sensitivity of GPP was high during the dry year of 2008 with limited soil moisture availability. Our results suggest the carbon balance of this temperate desert steppe was not only sensitive to total annual precipitation, but also to its seasonal distribution.

Functional group composition of organic aerosol from combustion emissions and secondary processes at two contrasted urban environments

NASA Astrophysics Data System (ADS)

El Haddad, Imad; Marchand, Nicolas; D'Anna, Barbara; Jaffrezo, Jean Luc; Wortham, Henri

2013-08-01

The quantification of major functional groups in atmospheric organic aerosol (OA) provides a constraint on the types of compounds emitted and formed in atmospheric conditions. This paper presents functional group composition of organic aerosol from two contrasted urban environments: Marseille during summer and Grenoble during winter. Functional groups were determined using a tandem mass spectrometry approach, enabling the quantification of carboxylic (RCOOH), carbonyl (RCOR‧), and nitro (RNO2) functional groups. Using a multiple regression analysis, absolute concentrations of functional groups were combined with those of organic carbon derived from different sources in order to infer the functional group contents of different organic aerosol fractions. These fractions include fossil fuel combustion emissions, biomass burning emissions and secondary organic aerosol (SOA). Results clearly highlight the differences between functional group fingerprints of primary and secondary OA fractions. OA emitted from primary sources is found to be moderately functionalized, as about 20 carbons per 1000 bear one of the functional groups determined here, whereas SOA is much more functionalized, as in average 94 carbons per 1000 bear a functional group under study. Aging processes appear to increase both RCOOH and RCOR‧ functional group contents by nearly one order of magnitude. Conversely, RNO2 content is found to decrease with photochemical processes. Finally, our results also suggest that other functional groups significantly contribute to biomass smoke and SOA. In particular, for SOA, the overall oxygen content, assessed using aerosol mass spectrometer measurements by an O:C ratio of 0.63, is significantly higher than the apparent O:C* ratio of 0.17 estimated based on functional groups measured here. A thorough examination of our data suggests that this remaining unexplained oxygen content can be most probably assigned to alcohol (ROH), organic peroxides (ROOH), organonitrates (RONO2) and/or organosulfates (ROSO3H).

Carbon dioxide utilisation of Dunaliella tertiolecta for carbon bio-mitigation in a semicontinuous photobioreactor.

PubMed

Farrelly, Damien J; Brennan, Liam; Everard, Colm D; McDonnell, Kevin P

2014-04-01

Bio-fixation of carbon dioxide (CO2) by microalgae has been recognised as an attractive approach to offset anthropogenic emissions. Biological carbon mitigation is the process whereby autotrophic organisms, such as microalgae, convert CO2 into organic carbon and O2 through photosynthesis; this process through respiration produces biomass. In this study Dunaliella tertiolecta was cultivated in a semicontinuous culture to investigate the carbon mitigation rate of the system. The algae were produced in 1.2-L Roux bottles with a working volume of 1 L while semicontinuous production commenced on day 4 of cultivation when the carbon mitigation rate was found to be at a maximum for D. tertiolecta. The reduction in CO2 between input and output gases was monitored to predict carbon fixation rates while biomass production and microalgal carbon content are used to calculate the actual carbon mitigation potential of D. tertiolecta. A renewal rate of 45 % of flask volume was utilised to maintain the culture in exponential growth with an average daily productivity of 0.07 g L(-1) day(-1). The results showed that 0.74 g L(-1) of biomass could be achieved after 7 days of semicontinuous production while a total carbon mitigation of 0.37 g L(-1) was achieved. This represented an increase of 0.18 g L(-1) in carbon mitigation rate compared to batch production of D. tertiolecta over the same cultivation period.

Modification of bamboo-based activated carbon using microwave radiation and its effects on the adsorption of methylene blue

NASA Astrophysics Data System (ADS)

Liu, Qing-Song; Zheng, Tong; Li, Nan; Wang, Peng; Abulikemu, Gulizhaer

2010-03-01

Modification of bamboo-based activated carbon was carried out in a microwave oven under N 2 atmosphere. The virgin and modified activated carbons were characterized by means of low temperature N 2 adsorption, acid-base titration, point of zero charge (pH pzc) measurement, FTIR and XPS spectra. A gradual decrease in the surface acidic groups was observed during the modification, while the surface basicity was enhanced to some extent, which gave rise to an increase in the pH pzc value. The species of the functional groups and relative content of various elements and groups were given further analysis using FTIR and XPS spectra. An increase in the micropores was found at the start, and the micropores were then extended into larger ones, resulting in an increase in the pore volume and average pore size. Adsorption studies showed enhanced adsorption of methylene blue on the modified activated carbons, caused mainly by the enlargement of the micropores. Adsorption isotherm fittings revealed that Langmuir and Freundlich models were applicable for the virgin and modified activated carbons, respectively. Kinetic studies exhibited faster adsorption rate of methylene blue on the modified activated carbons, and the pseudo-second-order model fitted well for all of the activated carbons.

Effects of vegetation restoration on the aggregate stability and distribution of aggregate-associated organic carbon in a typical karst gorge region

NASA Astrophysics Data System (ADS)

Tang, F. K.; Cui, M.; Lu, Q.; Liu, Y. G.; Guo, H. Y.; Zhou, J. X.

2015-08-01

Changes in soil utilization significantly affect aggregate stability and aggregate-associated soil organic carbon (SOC). A field investigation and indoor analysis were conducted in order to study the soil aggregate stability and organic carbon distribution in the water-stable aggregates (WSA) of the bare land (BL), grassland (GL), shrubland (SL), and woodland (WL) in a typical karst gorge region. The results indicated that the BL, GL, SL, and WL were dominated by particles with sizes > 5 mm under dry sieving treatment, and that the soil aggregate contents of various sizes decreased as the particle size decreased. In addition, the BL, GL, SL, and WL were predominantly comprised of WSA < 0.25 mm under wet sieving treatment, and that the WSA contents initially increased, then decreased, and then increased again as the particle size decreased. Furthermore, at a soil depth of 0-60 cm, the mean weight diameter (MWD), geometrical mean diameter (GMD), and fractal dimensions (D) of the dry aggregates and water-stable aggregates in the different types of land were ranked, in descending order, as WL > GL > SL > BL. The contents of WSA > 0.25 mm, MWD and GMD increased significantly, in that order, and the percentage of aggregate destruction (PAD) and fractal dimensions decreased significantly as the soil aggregate stability improved. The results of this study indicated that, as the SOC contents increased after vegetation restoration, the average SOC content of WL was 2.35, 1.37, and 1.26 times greater than that in the BL, GL, and SL, respectively. The total SOC and SOC associated in WSA of various sizes were the highest at a soil depth of 0-20 cm. In addition, the SOC contents of the WSA increased as the soil aggregate sizes decreased. The SOC contents of the WSA < 0.25 mm were highest except in the bare land, and the SOC contents of the aggregates < 0.25 mm, which ranged from 18.85 to 41.08 %, comprised the majority of the total aggregate SOC contents. The woodland and grassland facilitated WSA stability and SOC protection, thus, promoting the natural restoration of vegetation by reducing artificial disturbances could effectively restore the ecology of and prevent soil erosion in karst regions.

High tocopherol and triacylglycerol contents in Pinus pinea L. seeds.

PubMed

Nasri, Nizar; Tlili, Nizar; Ben Ammar, Kamel; Khaldi, Abdelhamid; Fady, Bruno; Triki, Saida

2009-01-01

Oleaginous seeds are among the functional foods most recognized for their tocopherols and triacylglycerols because of their role in lipid metabolism. In this paper, the tocopherol and triacylglycerol contents in seeds of several Pinus pinea L. populations around the Mediterranean Basin were investigated. Lipids were extracted from fully ripen seeds with petroleum ether. The tocopherol (alpha-tocopherol, gamma-tocopherol, and delta-tocopherol) contents were, respectively, 15.34+/-3.75 ppm, 1,681.75+/-404.03 ppm and 41.87+/-9.79 ppm. Lipids (mainly triacylglycerols) in P. pinea seeds averaged 48% on a dry weight basis. Triacylglycerols with an equivalent carbon number of 44 (32.27%) and of 46 (30.91%) were dominant. The major triacylglycerol was LLO (24.06%). Tocopherols and triacylglycerols were present at remarkably high levels, thus making P. pinea oil a valuable source of antioxidants and unsaturated fatty acids with varying levels across the geographical range of P. pinea.

[Relationships of soil organic carbon with its active and non-active components under different land use types in the middle reaches of Heihe River, China].

PubMed

Zhang, Jun-Hua; Li, Guo-Dong; Wang, Yan-Song; Nan, Zhong-Ren; Zhao, Li-Ping

2012-12-01

Taking the seven typical land use types (paddy field, dry land, medium coverage grassland, saline-alkali field, bare land, desert, and sandlot) in the middle reaches of Heihe River as test objects, this paper studied the relationships of soil organic carbon content with its components. In the 0-100 cm soil profile, the contents of soil total organic carbon (TOC) , active organic carbon (AOC), and non-active organic carbon (NOC) decreased with increasing depth. The soil TOC, AOC, and NOC contents differed with land use type. Land use change induced the increase or decrease of soil organic carbon content. The tillage in paddy field was an available way to increase the contents of soil TOC, AOC, and NOC. After land use change, soil NOC rather than AOC contributed more to soil TOC content. For the same land use types, soil AOC and NOC contents increased together with increasing soil TOC content, and the NOC content increased faster than the AOC content. The soil TOC content corresponding to the crossing point of the variation trend lines of soil AOC and NOC contents could be considered as the boundary point of TOC accumulation or loss, and the saturation capacities of soil AOC and NOC could be obtained by the variation trend lines of the AOC and NOC.

[Responses of microbial biomass P to the changes of organic C and P in paddy soils under different fertilization systems].

PubMed

Chen, An-Lei; Wang, Kai-Rong; Xie, Xiao-Li; Liu, Ying-Xin

2007-12-01

Based on a fifteen years field experiment in double rice-cropping region of subtropical China, the responses of microbial biomass P (MB-P) to organic C and P in red paddy soils under different fertilization systems were investigated. The results indicated that a long-term input of organic carbon sources and the increasing soil organic carbon made soil microbial biomass remain at a high level (MB-C > 800 mg x kg(-1)), being a main reason of the increase of MB-P. Under long-term zero chemical P fertilization, there was a significant decrease in soil total P (P < 0.05), but soil organic P increased by 29.3% on average. The inorganic P forms in deficit were mainly Al-P, Fe-P, Ca-P and O-P, with the lowest content of Al-P (only 0.5 mg x kg(-1) on average). The content of soil MB-P under zero chemical P fertilization was much higher than that of Olsen-P. Correlation analysis showed that there was a significant relationship (P < 0.05) between MB-P and Al-P, from which, it was deduced that the utilization of Al-P, Fe-P, Ca-P and O-P by soil microbes could be the key approach of promoting these P forms transformed into available P. Chemical P fertilization combined with organic nutrient recycling could not only enlarge the soil P pool, but also improve the P availability.

Annual variability in the radiocarbon age and source of dissolved CO2 in a peatland stream.

PubMed

Garnett, Mark H; Dinsmore, Kerry J; Billett, Michael F

2012-06-15

Radiocarbon dating has the capacity to significantly improve our understanding of the aquatic carbon cycle. In this study we used a new passive sampler to measure the radiocarbon ((14)C) and stable carbon (δ(13)C) isotopic composition of dissolved CO(2) for the first time in a peatland stream throughout a complete year (May 2010-June 2011). The in-stream sampling system collected time-integrated samples of CO(2) continuously over approximately 1 month periods. The rate of CO(2) trapping was proportional to independently measured streamwater CO(2) concentrations, demonstrating that passive samplers can be used to estimate the time-averaged dissolved CO(2) concentration of streamwater. While there was little variation and no clear trend in δ(13)CO(2) values (suggesting a consistent CO(2) source), we found a clear temporal pattern in the (14)C concentration of dissolved CO(2). The (14)C age of CO(2) varied from 707±35 to 1210±39 years BP, with the youngest CO(2) in the autumn and oldest in spring/early summer. Mean stream discharge and (14)C content of dissolved CO(2) were positively correlated. We suggest that the observed pattern in the (14)C content of dissolved CO(2) reflects changes in its origin, with older carbon derived from deeper parts of the peat profile contributing proportionally more gaseous carbon during periods of low stream flow. Copyright © 2012 Elsevier B.V. All rights reserved.

Extension of an assessment model of ship traffic exhaust emissions for particulate matter and carbon monoxide

NASA Astrophysics Data System (ADS)

Jalkanen, J.-P.; Johansson, L.; Kukkonen, J.; Brink, A.; Kalli, J.; Stipa, T.

2012-03-01

A method is presented for the evaluation of the exhaust emissions of marine traffic, based on the messages provided by the Automatic Identification System (AIS), which enable the positioning of ship emissions with a high spatial resolution (typically a few tens of metres). The model also takes into account the detailed technical data of each individual vessel. The previously developed model was applicable for evaluating the emissions of NOx, SOx and CO2. This paper addresses a substantial extension of the modelling system, to allow also for the mass-based emissions of particulate matter (PM) and carbon monoxide (CO). The presented Ship Traffic Emissions Assessment Model (STEAM2) allows for the influences of accurate travel routes and ship speed, engine load, fuel sulphur content, multiengine setups, abatement methods and waves. We address in particular the modeling of the influence on the emissions of both engine load and the sulphur content of the fuel. The presented methodology can be used to evaluate the total PM emissions, and those of organic carbon, elemental carbon, ash and hydrated sulphate. We have evaluated the performance of the extended model against available experimental data on engine power, fuel consumption and the composition-resolved emissions of PM. We have also compared the annually averaged emission values with those of the corresponding EMEP inventory, As example results, the geographical distributions of the emissions of PM and CO are presented for the marine regions of the Baltic Sea surrounding the Danish Straits.

Ecosystem Carbon Emissions from 2015 Forest Fires in Interior Alaska

NASA Technical Reports Server (NTRS)

Potter, Christopher S.

2018-01-01

In the summer of 2015, hundreds of wildfires burned across the state of Alaska, and consumed more than 1.6 million ha of boreal forest and wetlands in the Yukon-Koyukuk region. Mapping of 113 large wildfires using Landsat satellite images from before and after 2015 indicated that nearly 60% of this area was burned at moderate-to-high severity levels. Field measurements near the town of Tanana on the Yukon River were carried out in July of 2017 in both unburned and 2015 burned forested areas (nearly adjacent to one-another) to visually verify locations of different Landsat burn severity classes (low, moderate, or high). Results: Field measurements indicated that the loss of surface organic layers in boreal ecosystem fires is a major factor determining post-fire soil temperature changes, depth of thawing, and carbon losses from the mineral topsoil layer. Measurements in forest sites showed that soil temperature profiles to 30 cm depth at burned forest sites increased by an average of 8o - 10o C compared to unburned forest sites. Sampling and laboratory analysis indicated a 65% reduction in soil carbon content and a 58% reduction in soil nitrogen content in severely burned sample sites compared to soil mineral samples from nearby unburned spruce forests. Conclusions: Combined with nearly unprecedented forest areas severely burned in the Interior region of Alaska in 2015, total ecosystem fire emission of carbon to the atmosphere exceeded most previous estimates for the state.

Lignin phenols in sediments of Lake Baikal, Siberia: Application to paleoenvironmental studies

USGS Publications Warehouse

Orem, W.H.; Colman, Steven M.; Lerch, H.E.

1997-01-01

Sediments from three cores obtained from distinct depositional environments in Lake Baikal, Siberia were analyzed for organic carbon, total nitrogen and lignin phenol concentration and composition. Results were used to examine changes in paleoenvironmental conditions during climatic cycles of the late Quaternary (< 125 ka). Average organic carbon, and total nitrogen concentrations, atomic C/N ratios and organic carbon accumulation rates were significantly higher in the Holocene compared with the late Pleistocene, reflecting overall warmer temperatures and increased runoff during the Holocene. A Holocene maximum in organic carbon was observed at about 6 ka, and may represent the warmest wettest period of the Holocene. At one site (Academician Ridge) pronounced late Pleistocene maxima in organic carbon and biogenic silica were observed at about 80-85 ka, probably indicative of an interstadial period with enhanced aquatic productivity. Total sedimentary lignin phenol contents were generally lower in the late Pleistocene compared to the Holocene, but with several peaks in concentration during the late Pleistocene. These late Pleistocene peaks in total sedimentary lignin content (dated at about 80, 50 and 30 ka) directly precede or occur during peaks in sedimentary biogenic silica contents. These periods likely represent relatively warm interstadial times, with increased precipitation producing the observed increase in terrestrial runoff and aquatic productivity. Lignin phenol ratios (S/V, C/V and P/V) were used to examine changes in terrestrial vegetation type resulting from changes in paleoenvironmental conditions during the late Pleistocene. A degree of caution must be used in the interpretation of these ratios with regard to vegetation sources and paleoenvironmental conditions, because of potential compositional changes in lignin resulting from biodegradation. Nevertheless, results show that long glacial periods were characterized by terrestrial vegetation composed of a mix of non-woody angiosperm vegetation and minor gymnosperm forest. Shorter interstadial periods are defined by a change to dominant gymnosperm forest and were observed at about 80, 75, 63, 50 and 30 ka, ranging from about 2-6 kyr in duration. These interstadial periods of the late Pleistocene defined by lignin phenol ratios generally occur during longer periods of enhanced sedimentary biogenic silica content (about 10-15 ka in duration), providing corroborative evidence of these warm interstadial periods.Sediments obtained in Lake Baikal were analyzed for organic carbon, total nitrogen and lignin phenol composition and used to study changes in paleoenvironmental conditions during climatic cycles of the late Quaternary. The organic carbon, total nitrogen concentrations, atomic C/N ratios and organic carbon accumulation rates were higher in the Holocene showing overall warmer temperatures and increased runoff. Total lignin phenol contents were lower in the Pleistocene representing relatively warm interstadial times with increased precipitation, runoff and aquatic productivity. Lignin phenol was used to examine vegetation changes due to paleoenvironmental conditions and showed that long glacial periods were characterized by terrestrial vegetation.

Effect of carbon content on friction and wear of cast irons

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1977-01-01

Friction and wear experiments were conducted with cast irons and wrought steels containing various amounts of carbon in the alloy structure in contact with 52100 steel. Gray cast irons were found to exhibit lower friction and wear characteristics than white cast irons. Further, gray cast iron wear was more sensitive to carbon content than was white. Wear with gray cast iron was linearly related to load, and friction was found to be sensitive to relative humidity and carbon content. The form, in which the carbon is present in the alloy, is more important, as the carbon content and no strong relationship seems to exist between hardness of these ferrous alloys and wear.

[Distribution and source of particulate organic carbon and particulate nitrogen in the Yangtze River Estuary in summer 2012].

PubMed

Xing, Jian-Wei; Xian, Wei-Wei; Sheng, Xiu-Zhen

2014-07-01

Based on the data from the cruise carried out in August 2012 in the Yangtze River Estuary and its adjacent waters, spatial distributions of particulate organic carbon (POC), particulate nitrogen (PN) and their relationships with environmental factors were studied, and the source of POC and the contribution of phytoplankton to POC were analyzed combined with n (C)/n (N) ratio and chlorophyll a (Chl a) in the Yangtze River Estuary in summer 2012. The results showed that the concentrations of POC in the Yangtze River Estuary ranged from 0.68 mg x L(-1) to 34.80 mg x L(-1) in summer and the average content was 3.74 mg x L(-1), and PN contents varied between 0.03 mg x L(-1) and 9.13 mg x L(-1) with an average value of 0.57 mg x L(-1). Both of them presented that the concentrations in bottom layers were higher than those in the surface. POC and PN as well as total suspended matter (TSM) showed a extremel similar horizontal distribution trend that the highest values appeared in the near of the mouth and southwest of the survey waters, and decreased rapidly as toward the open seas, both of them showed higher contents in coastal zones and lower in outer sea. There was a fairly good positive linear relationship between POC and PN, which indicated that they had the same source. POC and PN expressed significantly positive correlations with TSM and chemical oxygen demand (COD), but showed relatively weak correlations with salinit and chlorophyll a, which demonstrated that terrestrial inputs had a strong influence on the distribution of POC and PN, and phytoplankton production was not the major source of organic matters in the Yangtze River Estuary. Both the n (C)/n (N) ratio and POC/Chl a analysis showed that the main source of POC was terrestrial inputs, and organic debris was the main existence form of POC. Quantitative analysis showed the biomass of phytoplankton only made an average of 2.54% contribution to POC in the Yangtze Rive Estuary in summer and non-living POC occupied the overwhelming advantage.

Radioactivity and geochemistry of selected mineral-spring waters in the Western United States; basic data and multivariate statistical analysis

USGS Publications Warehouse

Felmlee, J.K.; Cadigan, R.A.

1982-01-01

Multivariate statistical analyses were performed on data from 156 mineral-spring sites in nine Western States to analyze relationships among the various parameters measured in the spring waters. Correlation analysis and R-mode factor analysis indicate that three major factors affect water composition in the spring systems studied: (1) duration of water circulation, (2) depth of water circulation, and (3) partial pressure of carbon dioxide. An examination of factor scores indicates that several types of hydrogeologic systems were sampled. Most of the samples are (1) older water from deeper circulating systems having relatively high salinity, high temperature, and low Eh or (2) younger water from shallower circulating systems having relatively low salinity, low temperature, and high Eh. The rest of the samples are from more complex systems. Any of the systems can have a relatively high or low content of dissolved carbonate species, resulting in a low or high pH, respectively. Uranium concentrations are commonly higher in waters of relatively low temperature and high Eh, and radium concentrations are commonly higher in waters having a relatively high carbonate content (low pH) and, secondarily, relatively high salinity. Water samples were collected and (or) measurements were taken at 156 of the 171 mineral-spring sites visited. Various samples were analyzed for radium, uranium, radon, helium, and radium-228 as well as major ions and numerous trace elements. On-site measurements for physical properties including temperature, specific conductance, pH, Eh, and dissolved oxygen were made. All constituents and properties show a wide range of values. Radium concentrations range from less than 0.01 to 300 picocuries per liter; they average 1.48 picocuries per liter and have an anomaly threshold value of 171 picocuries per liter for the samples studied. Uranium concentrations range from less than 0.01 to 120 micrograms per liter and average 0.26 micrograms per liter; they have an anomaly threshold value of 48.1 micrograms per liter. Radon content ranges from less than 10 to 110,000 picocuries per liter, averages 549 picocuries per liter and has an anomaly threshold of 20,400 picocuries per liter. Helium content ranges from -1,300 to +13,000 parts per billion relative to atmospheric helium; it averages +725 parts per billion and has an anomaly threshold of 10,000 parts per billion. Radium-228 concentrations range from less than 2.0 to 33 picocuries per liter; no anomaly threshold was determined owing to the small number of samples. All of the anomaly thresholds may be somewhat high because the sampling was biased toward springs likely to be radioactive. The statistical variance in radium and uranium concentrations unaccounted for by the identified factors testifies to the complexity of some hydrogeologic systems. Unidentified factors related to geologic setting and the presence of uranium-rich rocks in the systems also affect the observed concentrations of the radioactive elements in the water. The association of anomalous radioactivity in several springs with nearby known uranium occurrences indicates that other springs having anomalous radioactivity may also be associated with uranium occurrences as yet undiscovered.

Latent effect of soil organic matter oxidation on mercury cycling within a southern boreal ecosystem.

PubMed

Gabriel, Mark; Kolka, Randy; Wickman, Trent; Woodruff, Laurel; Nater, Ed

2012-01-01

The focus of this study is to investigate processes causing the observed spatial variation of total mercury (THg) in the soil O horizon of watersheds within the Superior National Forest (Minnesota) and to determine if results have implications toward understanding long-term changes in THg concentrations for resident fish. Principal component analysis was used to evaluate the spatial relationships of 42 chemical elements in three soil horizons over 10 watersheds. Results indicate that soil organic carbon is the primary factor controlling the spatial variation of certain metals (Hg, Tl, Pb, Bi, Cd, Sn, Sb, Cu, and As) in the O and A soil horizons. In the B/E horizon, organic carbon appeared to play a minor role in metal spatial variation. These characteristics are consistent with the concentration of soil organic matter and carbon decreasing from the O to the B/E horizons. We also investigated the relationship between percent change in upland soil organic content and fish THg concentrations across all watersheds. Statistical regression analysis indicates that a 50% reduction in age-one and age-two fish THg concentration could result from an average 10% decrease in upland soil organic content. Disturbances that decrease the content of THg and organic matter in the O and A horizons (e.g., fire) may cause a short-term increase in atmospherically deposited mercury but, over the long term, may lead to decreased fish THg concentrations in affected watersheds. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Determination of ash in coals unusually high in calcite and pyrite

USGS Publications Warehouse

Rees, O.W.; Selvig, W.A.

1942-01-01

The preliminary hearth heating method (A and E) gave results within the A. S. T. M. tolerances for all duplicates obtained in the same laboratory. Checks between different laboratories within A. S. T. M. tolerances were obtained for coals containing up to about 3.6 per cent mineral carbon dioxide, but these ashes contained larger amounts of retained sulfur. The determination of ash by the cold furnace method (B and F) gave duplicate results within A. S. T. M. tolerances for all samples in the U. S. Bureau of Mines laboratory and for samples up to about 1.6 per cent mineral carbon dioxide content in the Illinois Geological Survey laboratory. Checks between average values from the two laboratories were within A. S. T. M. tolerances for all samples.

Undegassed Carbon Content from a Highly Depleted Segment of the Mid-Atlantic Ridge (1-5°S): Evidence from Melt Inclusions

NASA Astrophysics Data System (ADS)

Le Voyer, M.; Kelley, K. A.; Cottrell, E.; Hauri, E. H.

2014-12-01

As carbon solubility is low in basalts, MORB contain little dissolved CO2 (189±61 ppm, 1σ, n=600 [1]). A global negative correlation between CO2/Nb (proxy for amount of CO2 lost by degassing) and Ba/La (proxy for source enrichment) indicates that depleted MORB are less affected by degassing than enriched MORB: CO2/Nb ratios range from 0-100 for samples with Ba/La>4, while CO2/Nb range from 50 to 400 for samples with Ba/La<4 [1]. To assess the CO2 content of undegassed MORB, we analyzed the volatile content of 70 olivine-hosted, glassy melt inclusions (MIs) from four basalts dredged along MAR 1-5°S, a ridge segment that produces highly depleted MORB in terms of trace element enrichment and radiogenic isotopes [2, 3]. MIs contain CO2 contents (180-1420 ppm) that are higher than their respective matrix glasses (130-220 ppm, typical for vapor-saturated melts erupted at 3-5 km b.s.l.). One of the four dredges (EN061 5D-3Ag) contains MIs that do not exhibit shrinkage bubbles. For this sample only, we find a positive correlation between the CO2 content (240-770 ppm) and the Cl content (6-20 ppm) of the MIs that is not found in the matrix glasses (see Fig.). We infer that the correlation between CO2 and Cl, both highly incompatible in silicate minerals during fractional crystallization, is strong evidence for vapor-undersaturation, as any CO2 degassing would have erased the correlation. Together with MIs from the Siqueiros Fracture Zone [4] and from northern Iceland [5], the MIs from EN061 5D-3Ag may represent another occurrence of carbon-undersaturated MORB. Our results will be used to model the primary carbon content of MORB and of the depleted upper mantle. Note that the average Cl content of the matrix glasses (20±1 ppm) is higher than those of the MIs (12±3 ppm, see Fig.). This indicates either that the matrix glasses assimilated a small amount of seawater Cl, or that the MIs are all more depleted than the matrix glass. We will acquire major and trace element data in order to further investigate the origin of the low Cl and high CO2 contents in these MIs. Ref. [1] Le Voyer et al. 2014 Goldschmidt abstr. [2] Schilling et al. 1994 JGR 99 [3] Kelley et al. 2013 G3 [4] Saal et al. 2002 Nature 419 [5] Hauri and Saal 2009 EOS Fall suppl. AGU abstr.

[Effects of Rice Cultivar and Typical Soil Improvement Measures on the Uptake of Cd in Rice Grains].

PubMed

Wang, Mei-e; Peng, Chi; Chen, Wei-ping

2015-11-01

Cadmium pollution of rice is a big problem in agricultural food safety. The accident "Cd rice" occurred last year in Youxian County, Hunan Province caused serious social panic. In this study, trials on "Cd rice" controlling techniques specific to the Cd pollution in paddy soil in Youxian were investigated. It was suggested that the average Cd contents in rice grains of the rice variety "Zhu Liang You 06" in Datongqiao and Wangling were 0.167 and 0.127 mg x kg(-1), respectively, which were only equal to 20% of the contents of other varieties. The trials for stabilizing agents revealed that treatments of lime and mineral fertilizer decreased Cd contents in rice grains to 20-30% of the control. Plastic film-mulched treatment decreased the rice grain Cd to 50%. And combined treatment of plastic film-mulched and biochar and silicon foliar-fertilizer decreased 80% of rice Cd content. Single treatments of silicon foliar-fertilizer and combined treatment of silicon foliar-fertilizer and topdressing fertilizer decreased more than 90% of Cd content. Results of BCR revealed that the percentage of cationic exchangeable and/or carbonate associated Cd fraction was more than 55% for most of the soil samples. Lime treatment significantly decreased the percentage of cationic exchangeable and/or carbonate and oxides of Fe and Mn associated Cd and increased the crystalline structure of clay minerals associated Cd. The change rate reached about 20%. Our results suggested concentration of soil Cd and pH were the two significant factors impacting the uptake of Cd by rice grains.

40 CFR 98.336 - Data reporting requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... carbon analysis (percent by weight, expressed as a decimal fraction). (11) Whether carbon content of the...) Carbon content of each carbon-containing input material charged to each kiln or furnace (including zinc bearing material, flux materials, and other carbonaceous materials) from the annual carbon analysis for...

Pore-scale investigation on the response of heterotrophic respiration to moisture conditions in heterogeneous soils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yan, Zhifeng; Liu, Chongxuan; Todd-Brown, Katherine E.

The relationship between microbial respiration rate and soil moisture content is an important property for understanding and predicting soil organic carbon degradation, CO 2 production and emission, and their subsequent effects on climate change. This paper reports a pore-scale modeling study to investigate the response of heterotrophic respiration to moisture conditions in soils and to evaluate various factors that affect this response. X-ray computed tomography was used to derive soil pore structures, which were then used for pore-scale model investigation. The pore-scale results were then averaged to calculate the effective respiration rates as a function of water content in soils.more » The calculated effective respiration rate first increases and then decreases with increasing soil water content, showing a maximum respiration rate at water saturation degree of 0.75 that is consistent with field and laboratory observations. The relationship between the respiration rate and moisture content is affected by various factors, including pore-scale organic carbon bioavailability, the rate of oxygen delivery, soil pore structure and physical heterogeneity, soil clay content, and microbial drought resistivity. Simulations also illustrates that a larger fraction of CO 2 produced from microbial respiration can be accumulated inside soil cores under higher saturation conditions, implying that CO 2 flux measured on the top of soil cores may underestimate or overestimate true soil respiration rates under dynamic moisture conditions. Overall, this study provides mechanistic insights into the soil respiration response to the change in moisture conditions, and reveals a complex relationship between heterotrophic microbial respiration rate and moisture content in soils that is affected by various hydrological, geochemical, and biophysical factors.« less

40 CFR 600.510-12 - Calculation of average fuel economy and average carbon-related exhaust emissions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 29 2010-07-01 2010-07-01 false Calculation of average fuel economy and average carbon-related exhaust emissions. 600.510-12 Section 600.510-12 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) ENERGY POLICY FUEL ECONOMY AND CARBON-RELATED EXHAUST EMISSIONS OF MOTOR VEHICLES Fuel Economy Regulation...

Towards a consistent mantle carbon flux estimate: Insights from volatile systematics (H 2O/Ce, δD, CO 2/Nb) in the North Atlantic mantle (14° N and 34° N)

NASA Astrophysics Data System (ADS)

Cartigny, Pierre; Pineau, Françoise; Aubaud, Cyril; Javoy, Marc

2008-01-01

In order to better characterise mantle CO 2/Nb-variability, we obtained and compiled major and trace elements, content and isotope composition of both CO 2 and water on two series of mid-ocean ridge basalt (MORB) samples dredged at ˜ 14° N ( n = 6) and 34° N ( n = 11) on the mid-Atlantic ridge. All samples are carbon-saturated. One, the so-called popping rock 2ΠD43 kept its vesicles, the initial (pre-degassing) C-contents of the 16 other samples being reconstructed from their assumed degassing history. For water, the samples show large variations, from 1300 to 6900 ppm and from 1900 to 7900 ppm with associated δD-values ranging from - 55 to - 79‰ and from - 55 to - 88‰ for samples at 14° N and 34° N respectively. For carbon, the inferred initial predegassing contents vary greatly, from 660 to 14,700 ppmCO 2 and from 1400 to 57,600 ppmCO 2 for samples at 14° N and 34° N respectively. Measured Nb-contents range from 4.5 to 29.6 ppm show both good agreement with previously published data and positive correlations with reconstructed initial CO 2-contents. The mean CO 2/Nb range from ˜ 570 to ˜ 730 at 14° N and 34° N respectively. CO 2 and Nb data for the two undegassed samples available so far (i.e. the popping rock of the present study and the basaltic glasses from the Siqueiros transform fault from the study of Saal et al., 2002) show significant variations in CO 2/Nb over a factor of 2 and thus questions the constant CO 2/Nb previously emphasised for these two samples, this view being supported by CO 2/Nb-ratios of samples whose initial C-contents were reconstructed. For incompatible elements such as Ce, K and including water, a comparison of the geochemical characteristics of transform fault basaltic magmatism with other MORB systems shows magma transform fault magmatism to be unrepresentative of mantle compositions. Assuming a more appropriate average MORB CO 2/Nb-ratio of ˜ 530 and a mean MORB Nb-content of 3.31-1.8+3.99, we computed a mantle carbon flux of 2.3-1.3+2.7 × 10 12 mol/yr, a value actually consistent with that derived from C/ 3He systematics.

Flux of particulate matter through copepods in the Northeast water polynya

NASA Astrophysics Data System (ADS)

Daly, Kendra L.

1997-01-01

Particulate organic carbon (POC) and nitrogen (PON) production by large calanoid copepods was investigated on the northeast Greenland shelf during August 1992 and May to August 1993. Both Calanus hyperboreus and C. glacialis females, when suspended in seawater collected from the chlorophyll maximum, produced about 40 pellets per day, which contained a carbon and nitrogen content equivalent to 8% and 6% of body carbon, respectively, and 2% of body nitrogen. In experiments, the carbon:nitrogen (C:N) ratio by weight of suspended particulates, C. hyperboreus, and fecal pellets was 6.7, 7.7 and 28.5, respectively. The unusually high C:N ratio for pellets, in part, may be attributed to elevated ratios of > 20μm size fractions of particulate organic matter, the size fraction more common in the diet of these large copepods and the fraction dominated by diatoms according to microscopic and pigment data. The implied elevated C:N ratios of large phytoplankton cells were probably due to nitrogen deficiency, as shown by other studies in this region. In addition, female C. hyperboreus appeared to be more efficient in assimilating nitrogen than carbon, which also would have contributed to high C:N ratios in egested pellets. Unfractionated POC concentrations explained 54% of the variability in carbon egestion and 70% of the variability in nitrogen egestion in copepods, whereas copepod body content accounted for little of the variation on the short time scales of the experiments. Carbon egestion by C. hyperboreus was positively correlated with POC concentrations at the depth of the chlorophyll maximum, while nitrogen egestion was negatively correlated with PON concentrations in the euphotic zone. Estimates of potential community egestion rates for the upper water column indicate that copepods represent a major pathway of organic carbon transformation in this Arctic shelf system. On average, copepods may have ingested 45% of the primary production and egested fecal matter equivalent to 20% of the carbon and 12% of the nitrogen particulate flux sedimenting from the surface layer. However, several lines of evidence suggest that pellets were remineralized in the water column and, hence, may have contributed little organic carbon and nitrogen to the benthos.

Pyrolysis of chromium rich tanning industrial wastes and utilization of carbonized wastes in metallurgical process.

PubMed

Tôrres Filho, Artur; Lange, Liséte Celina; de Melo, Gilberto Caldeira Bandeira; Praes, Gustavo Eduardo

2016-02-01

Pyrolysis is the thermal degradation of organic material in oxygen-free or very lean oxygen atmosphere. This study evaluates the use of pyrolysis for conversion of leather wastes from chromium tanning processes into Carbonized Leather Residues (CLR), and the utilization of CLR in metallurgical processes through the production of iron ore pellets. CLR was used to replace mineral coal in proportions of 10% and 25% on fixed carbon basis content in the mixtures for pellets preparation. Experimental conversions were performed on a pilot scale pyrolysis plant and a pelletizing reactor of the "pot grate" type. The results demonstrated the technical feasibility of using the charcoal product from animal origin as an energy source, with recovery of up to 76.47% of chromium contained in CLR in the final produced of iron ore pellets. Pellets with 25% replacement of fixed carbon in the coal showed an enhanced compressive strength, with an average value of 344kgfpellet(-1), compared to 300kgfpellet(-1) for standard produced pellets. Copyright © 2015. Published by Elsevier Ltd.

The influence of saltmarsh restoration on sediment dynamics and the potential impact on carbon sequestration

NASA Astrophysics Data System (ADS)

Taylor, Benjamin; Paterson, David

2017-04-01

Coastal wetland ecosystems can act as large-capacity carbon sinks, providing a valuable climate change mitigation function. Globally, saltmarshes are estimated to accumulate an average of 244.7g C m-2 yr-1 (Ouyang & Lee 2014). Saltmarsh areas have experienced rapid loss in the recent past of approximately 1-2% per year (Duarte et al. 2008). Efforts to restore these areas could result in additional carbon storage due to extended vegetation cover and altered burial due to changing sediment dynamics. The influence of restoration through transplantation on sediment dynamics within a small estuary on the east coast of Scotland was assessed. Restoration efforts have been implemented since the early 2000s providing examples of old established sites ("old", >10years), young recently planted sites ("young", <5years), and 'business-as-usual' mudflats and natural marsh areas. In each of these area types seasonal data of sediment deposition and settlement were collected and sediment accretion rates measured. Deposition and settlement samples were taken four times a season, provided total sediment weight and organic content information. Elevation changes were measured once per season, quantifying sediment accretion rates. All data were collected between summer 2015 and spring 2016. Data suggest a positive correlation between sediment settlement and deposition quantities (dry weight) across the estuary (r2=0.64), with restored areas displaying a slightly stronger relationship (old r2=0.67, young r2=0.68) compared to natural marsh and mudflats (r2=0.54 and 0.59 respectively). Suggesting restored areas which are developing or expanding are retaining more from the potential sediment load in the water column. However average amounts of actual deposited material are significantly greater in mudflat and young areas with old and natural areas significantly lower; potentially as a result of those being of a lower elevation. Nevertheless, percentage organic matter content of deposited material is significantly lower in mudflat and young areas (3.78 ± 0.59% and 3.66 ± 0.79% respectively) versus those of natural and old areas (12.08 ± 2.27% and 6.70 ± 1.30% respectively). This relationship suggests that older restored areas are potentially offering the most potential benefit in terms of carbon sequestration, due to higher rates of deposition from the potential load and higher percentage organic content of those deposits. Furthermore, measurements of sediment accretion rates over the same period show natural and old areas to be the most effective at retaining sediment, with average elevation changes of 6.99 ± 1.64mm and 6.56 ± 0.94mm respectively, in comparison to young areas, 4.44 ± 1.58mm, and mudflats, 1.51 ± 1.23mm. Factors influencing these differences could be attributed to type and density of vegetation present and elevation of each area (or immersion period). However, the data suggests restoration could play an important role, which once established, appears to facilitate efficient sediment deposition from potential sediment load and crucially the effective accumulation of organic rich material through sediment accretion, possibly leading to increased carbon sequestration and climate change mitigation services.

Identification of Preferential Paths of Fossil Carbon within Water Resource Recovery Facilities via Radiocarbon Analysis.

PubMed

Tseng, Linda Y; Robinson, Alice K; Zhang, Xiaying; Xu, Xiaomei; Southon, John; Hamilton, Andrew J; Sobhani, Reza; Stenstrom, Michael K; Rosso, Diego

2016-11-15

The Intergovernmental Panel on Climate Change (IPCC) reported that all carbon dioxide (CO 2 ) emissions generated by water resource recovery facilities (WRRFs) during treatment are modern, based on available literature. Therefore, such emissions were omitted from IPCC's greenhouse gas (GHG) accounting procedures. However, a fraction of wastewater's carbon is fossil in origin. We hypothesized that since the fossil carbon entering municipal WRRFs is mostly from soaps and detergents as dissolved organic matter, its fate can be selectively determined during the universally applied separation treatment processes. Analyzing radiocarbon at different treatment points within municipal WRRFs, we verified that the fossil content could amount to 28% in primary influent and showed varying distribution leaving different unit operations. We recorded the highest proportion of fossil carbon leaving the secondary treatment as off-gas and as solid sludge (averaged 2.08 kg fossil-CO 2 -emission-potential m -3 wastewater treated). By including fossil CO 2 , total GHG emission in municipal WRRFs increased 13%, and 23% if an on-site energy recovery system exists although much of the postdigestion fossil carbon remained in biosolids rather than in biogas, offering yet another carbon sequestration opportunity during biosolids handling. In comparison, fossil carbon contribution to GHG emission can span from negligible to substantial in different types of industrial WRRFs. With such a considerable impact, CO 2 should be analyzed for each WRRF and not omitted from GHG accounting.

Synthesis and capacitance properties of N-doped porous carbon/NiO nanosheet composites using coal-based polyaniline as carbon and nitrogen source

NASA Astrophysics Data System (ADS)

Wang, Xiaoqin; Li, Qiaoqin; Zhang, Yong; Yang, Yufei; Cao, Zhi; Xiong, Shanxin

2018-06-01

A novel synthesis approach of N-doped porous carbon (NPC)/NiO composites possessing some honeycomb-shaped nanoporous carbon and plentiful NiO nanosheets is exploited. First NPC/Ni composites are achieved with NPC yield of 52.9% through a catalytic pyrolysis method, using coal-based polyaniline particles prepared by an in-situ polymerization method as a carbon and nitrogen source, and nickel particles as a catalyst, respectively. Next NPC/NiO composites are achieved unexpectedly with plentiful NiO nanosheets and N content of 1.00 wt% after a liquid oxidation process. In NPC/NiO composites, porous carbon mainly presents in the amorphous state, while the incorporated nitrogen mainly presents in the form of pyrrolic N (92.9 at.%) and oxidized N (7.1 at.%). Plentiful NiO nanosheets are embedded in the pores or on the NPC surface. 33.3 at.% Ni2O3 components exist in the surface of NiO nanosheets. NPC/NiO composites possess not only rich micropores, but also significant mesopores and nanoscale macropores. The BET specific surface area, BET average pore width and BJH adsorption average pore diameter are 627.5 m2/g, 2.0 nm and 5.1 nm, respectively. NPC/NiO composites demonstrate a high specific capacitance of 404.1 F/g at 1 A/g, and a good cycling stability maintaining high specific capacitance of 212.4 F/g (84.3% of the initial capacitance) at 5 A/g after 5000 cycles of charge and discharge, attributed to some honeycomb-shaped nanopores of carbon and large specific surface area of NiO nanosheets, and the synergistic effects between electric double-layer capacitance of NPC and pseudocapacitance of NiO. This study may provide a novel approach for the value-added applications of low-rank coal.

The Influence of Calcium Carbonate Composition and Activated Carbon in Pack Carburizing Low Carbon Steel Process in The Review of Hardness and Micro Structure

NASA Astrophysics Data System (ADS)

Hafni; Hadi, Syafrul; Edison

2017-12-01

Carburizing is a way of hardening the surface by heating the metal (steel) above the critical temperature in an environment containing carbon. Steel at a temperature of the critical temperature of affinity to carbon. Carbon is absorbed into the metal form a solid solution of carbon-iron and the outer layer has high carbon content. When the composition of the activator and the activated charcoal is right, it will perfect the carbon atoms to diffuse into the test material to low carbon steels. Thick layer of carbon Depending on the time and temperature are used. Pack carburizing process in this study, using 1 kg of solid carbon derived from coconut shell charcoal with a variation of 20%, 10% and 5% calcium carbonate activator, burner temperature of 950 0C, holding time 4 hours. The test material is low carbon steel has 9 pieces. Each composition has three specimens. Furnace used in this study is a pack carburizing furnace which has a designed burner box with a volume of 1000 x 600 x 400 (mm3) of coal-fired. Equipped with a circulation of oxygen from the blower 2 inches and has a wall of refractory bricks. From the variation of composition CaCO3, microstructure formed on the specimen with 20% CaCO3, better diffusion of carbon into the carbon steel, it is seen by the form marten site structure after quenching, and this indicates that there has been an increase of or adding carbon to in the specimen. This led to the formation of marten site specimen into hard surfaces, where the average value of hardness at one point side (side edge) 31.7 HRC

Potency of bio-charcoal briquette from leather cassava tubers and industrial sludge

NASA Astrophysics Data System (ADS)

Citrasari, Nita; Pinatih, Tety A.; Kuncoro, Eko P.; Soegianto, Agoes; Salamun, Irawan, Bambang

2017-06-01

The purpose of this study was to determine the quality of the bio-charcoal briquette with materials from leather cassava tubers and sludge of wastewater treatment plant. The first, bio-charcoal briquette analized stability test and compressive strength. Then, bio-charcoal briquette with best value analyzed for parameter including moisture content, ash content, calorific content, and burned test. The result briquette quality based on compressive strength for bio-charcoal briquettes carbonated water content between 3.8%-4.5% and non-carbonated bio-charcoal briquettes between 5.2%-7.6%. Bio-charcoal carbonation briquette ash content was between 5.30%-7.40% and non-carbonated bio-charcoal briquettes was between 6.86%-7.46%. Bio-charcoal carbonation levels briquettes heated between 578.2 calories/g-1837.7 calories/g and non carbonatedbio-charcoal briquettes between 858.1 calories/g-891.1 calories/g. Carbonated bio-charcoal burned test was between 48-63 minutes and non-carbonated bio-charcoal was between 22-42 minutes. Emissions resulted from the bio-charcoal briquettes for carbonated and non carbonated composition according to the government regulations ESDM No. 047 of 2006 which, at 128 mg/Nm3 and 139 mg/Nm3.

40 CFR 98.316 - Data reporting requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... analysis results of carbon content of petroleum coke as determined for QA/QC of supplier data under § 98...). (9) Monthly carbon content factor of petroleum coke from the supplier (percent by weight expressed as a decimal fraction). (10) Whether monthly carbon content of the petroleum coke is based on reports...

In situ one-step synthesis of hierarchical nitrogen-doped porous carbon for high-performance supercapacitors.

PubMed

Jeon, Ju-Won; Sharma, Ronish; Meduri, Praveen; Arey, Bruce W; Schaef, Herbert T; Lutkenhaus, Jodie L; Lemmon, John P; Thallapally, Praveen K; Nandasiri, Manjula I; McGrail, Benard Peter; Nune, Satish K

2014-05-28

A hierarchically structured nitrogen-doped porous carbon is prepared from a nitrogen-containing isoreticular metal-organic framework (IRMOF-3) using a self-sacrificial templating method. IRMOF-3 itself provides the carbon and nitrogen content as well as the porous structure. For high carbonization temperatures (950 °C), the carbonized MOF required no further purification steps, thus eliminating the need for solvents or acid. Nitrogen content and surface area are easily controlled by the carbonization temperature. The nitrogen content decreases from 7 to 3.3 at % as carbonization temperature increases from 600 to 950 °C. There is a distinct trade-off between nitrogen content, porosity, and defects in the carbon structure. Carbonized IRMOFs are evaluated as supercapacitor electrodes. For a carbonization temperature of 950 °C, the nitrogen-doped porous carbon has an exceptionally high capacitance of 239 F g(-1). In comparison, an analogous nitrogen-free carbon bears a low capacitance of 24 F g(-1), demonstrating the importance of nitrogen dopants in the charge storage process. The route is scalable in that multi-gram quantities of nitrogen-doped porous carbons are easily produced.

Influences of carbon content and coating carbon thickness on properties of amorphous CoSnO3@C composites as anode materials for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Fan, Fuqiang; Fang, Guoqing; Zhang, Ruixue; Xu, Yanhui; Zheng, Junwei; Li, Decheng

2014-08-01

A series of core-shell carbon coated amorphous CoSnO3 (CoSnO3@C) with different carbon content are synthesized. Effects of carbon content and coating carbon thickness on the physical and electrochemical performances of the samples were studied in detail. The samples were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), thermal gravimetric analysis (TGA), galvanostatic charge-discharge and AC impedance spectroscopy, respectively. The results indicate that controlling the concentration of aqueous glucose solution influences the generation of in-situ carbon layer thickness. The optimal concentration of aqueous glucose solution, carbon content and carbon layer thickness are suggested as 0.25 M, 35.1% and 20 nm, respectively. CoSnO3@C composite prepared under the optimal conditions exhibits excellent cycling performance, whose reversible capacity could reach 491 mA h g-1 after 100 cycles.

Identifying sources of dissolved organic carbon in agriculturally dominated rivers using radiocarbon age dating: Sacramento-San Joaquin River Basin, California

USGS Publications Warehouse

Sickman, James O.; DiGiorgio, Carol L.; Davisson, M. Lee; Lucero, Delores M.; Bergamaschi, Brian A.

2010-01-01

We used radiocarbon measurements of dissolved organic carbon (DOC) to resolve sources of riverine carbon within agriculturally dominated landscapes in California. During 2003 and 2004, average Δ14C for DOC was −254‰ in agricultural drains in the Sacramento–San Joaquin Delta, −218‰ in the San Joaquin River, −175‰ in the California State Water Project and −152‰ in the Sacramento River. The age of bulk DOC transiting the rivers of California’s Central Valley is the oldest reported for large rivers and suggests wide-spread loss of soil organic matter caused by agriculture and urbanization. Using DAX 8 adsorbent, we isolated and measured 14C concentrations in hydrophobic acid fractions (HPOA); river samples showed evidence of bomb-pulse carbon with average Δ14C of 91 and 76‰ for the San Joaquin and Sacramento Rivers, respectively, with older HPOA, −204‰, observed in agricultural drains. An operationally defined non-HPOA fraction of DOC was observed in the San Joaquin River with seasonally computed Δ14C values of between −275 and −687‰; the source of this aged material was hypothesized to be physically protected organic-matter in high clay-content soils and agrochemicals (i.e., radiocarbon-dead material) applied to farmlands. Mixing models suggest that the Sacramento River contributes about 50% of the DOC load in the California State Water Project, and agricultural drains contribute approximately one-third of the load. In contrast to studies showing stabilization of soil carbon pools within one or two decades following land conversion, sustained loss of soil organic matter, occurring many decades after the initial agricultural-land conversion, was observed in California’s Central Valley.

Carbon Sequestration of Caesalpinia platyloba S. Watt (Leguminosae) (Lott 1985) in the Tropical Deciduous Forest.

PubMed

Diaz-Gustavo, Norma; Martínez-Salvador, Martín; García-Hernández, José Luís; Norzagaray-Campos, Mariano; Luna-González, Antonio; González-Ocampo, Héctor Abelardo

2015-01-01

Caesalpinia platyloba was evaluated as an alternative for the retention of atmospheric carbon and as a feasible and viable economic activity in terms of income for tropical deciduous forest (TDF) peasants in the carbon markets. A total of 110 trees of C. platyloba from plantations and a TDF in the Northwest of Mexico were sampled. Growth (increase in height, diameter, and volume curves) was adjusted to assess their growth. Growth of individuals (height, diameter at breast height [DBH], age, and tree crown cover) was recorded. The Schumacher model (H = β(0)e(β1 • E-1)), by means of the guided curve method, was used to adjust growth models. Information analysis was made through the non-linear procedure with the multivariate secant or false position (DUD) method using the SAS software. Growth and increase models revealed acceptable adjustments (pseudo R(2)>0.8). C. platyloba reaches >8m of height with 12 cm in diameter and 550 cm(3) of volume, presenting the highest increase at 11 years considered as basal age. Highest significant density of wood was in good quality sites (0.80 g • cm(-3)), with a carbon content (average of 99.15tC • ha(-1)) at the highest density of 2500 trees • ha(-1) (without thinning). Average incomes of US$483.33tC • ha(-1) are expected. The profitability values (NPW = US$81,646.65, IRR = 472%, and B/C = 0.82) for C. platyloba make its cultivation a viable and profitable activity, considering a management scheme of the income derived from wood selling and from carbon credits.

Crystallinity and compositional changes in carbonated apatites: Evidence from 31P solid-state NMR, Raman, and AFM analysis

NASA Astrophysics Data System (ADS)

McElderry, John-David P.; Zhu, Peizhi; Mroue, Kamal H.; Xu, Jiadi; Pavan, Barbara; Fang, Ming; Zhao, Guisheng; McNerny, Erin; Kohn, David H.; Franceschi, Renny T.; Holl, Mark M. Banaszak; Tecklenburg, Mary M. J.; Ramamoorthy, Ayyalusamy; Morris, Michael D.

2013-10-01

Solid-state (magic-angle spinning) NMR spectroscopy is a useful tool for obtaining structural information on bone organic and mineral components and synthetic model minerals at the atomic-level. Raman and 31P NMR spectral parameters were investigated in a series of synthetic B-type carbonated apatites (CAps). Inverse 31P NMR linewidth and inverse Raman PO43-ν1 bandwidth were both correlated with powder XRD c-axis crystallinity over the 0.3-10.3 wt% CO32- range investigated. Comparison with bone powder crystallinities showed agreement with values predicted by NMR and Raman calibration curves. Carbonate content was divided into two domains by the 31P NMR chemical shift frequency and the Raman phosphate ν1 band position. These parameters remain stable except for an abrupt transition at 6.5 wt% carbonate, a composition which corresponds to an average of one carbonate per unit cell. This near-binary distribution of spectroscopic properties was also found in AFM-measured particle sizes and Ca/P molar ratios by elemental analysis. We propose that this transition differentiates between two charge-balancing ion-loss mechanisms as measured by Ca/P ratios. These results define a criterion for spectroscopic characterization of B-type carbonate substitution in apatitic minerals.

Methane in the Upper Silesian Coal Basin (Poland) - problem of reserves and exploitation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wojcik, A.J.

1995-08-01

The Upper Silesian Coal Basin (USCB) is the best recognized and the most productive coal basin in Poland. The USCB is primarily defined by the extent of Carboniferous coal-bearing formations. The sedimentary fill displays the stratigraphic record of major progressive inversion phases of the entire Moravo-Silesian basin during the late and post-geosynclinal period of the Variscan orogeny. According to the last estimates the coal reserves occurring above the depth limit of 1500 in are as follows: documented reserves - 58 billion tons, prognostic reserves - 46 billion tons, total - 104 billion tons. The coal type is predominantly vitrinitic, andmore » ash content is reported to be in the range of 11-17% and average sulphur content is 1.13%. The rank of USCB coal is largely controlled by complex coalification processes. It ranges from high volatile bituminous B, through medium volatile bituminous to high rank special coal semi anthracite and anthracite. The methane content of coal seams in USCB varies in a very broad range of 0-22 m{sup 3}/t coal (dry, ash free basis). The average gas content increases considerably within the depth range 600-1000 in from 0.99 to 4.68 m{sup 3}/t coal (daf). In deeper horizons it is more or less stable varying within the range of 4.7-7.0 m{sup 3}/t coal (daf). By this estimate, on average, the methane content is about 12,5 m{sup 3}/ton. There are several estimates of coal-bed methane resources in the USCB based on different methods. The resources are as follows: documented deposits in active mines to 1000 m: 370 BCM, undeveloped deposits to 1000 in: 340 BCM, deposit between 1000 and 1500 m: 590 BCM, total: 1300 BCM. The coalbed gas from this basin is primarily composed of saturated hydrocarbons and Nitrogen which amount to 97 volume percent. The rest is dominant by Carbon dioxide and Hydrogen.« less

High permeable microporous structured carbon counter electrode assisted by polystyrene sphere for fully printable perovskite solar cells

NASA Astrophysics Data System (ADS)

Tao, Haijun; Li, Yongtao; Zhang, Chuanxiang; Wang, Kang; Wang, Jiayue; Tan, Bin; Han, Linxuan; Tao, Jie

2018-03-01

The permeability of the carbon counter electrode (CCE) is critical to the HTM-free fully printable perovskite solar cells. In this work, we report a CCE assisted by polystyrene spheres (PS-spheres) as pore-forming agent to gain microporous structure for a better permeability. Due to its decomposition temperature at 400 °C, the porous structure is obtained in the carbon layer easily. By optimization towards the contents of PS-spheres in CCE, the filling rate of perovskite solution and the photovoltaic performance of the device have been significantly improved. Using this method, an average efficiency enhancement of 22% has been obtained for HTM-free fully printable perovskite solar cells, resulting in a better fill rate of CH3NH3PbI3 and an efficiency of 4.49%. This kind of CCE with the advantages of simple, easy preparation process and well performance, show excellent potential application in perovskite solar cells.

Salinity of the Eocene Arctic Ocean from oxygen isotope analysis of fish bone carbonate

NASA Astrophysics Data System (ADS)

Waddell, Lindsey M.; Moore, Theodore C.

2008-03-01

Stable isotope analysis was performed on the structural carbonate of fish bone apatite from early and early middle Eocene samples (˜55 to ˜45 Ma) recently recovered from the Lomonosov Ridge by Integrated Ocean Drilling Program Expedition 302 (the Arctic Coring Expedition). The δ18O values of the Eocene samples ranged from -6.84‰ to -2.96‰ Vienna Peedee belemnite, with a mean value of -4.89‰, compared to 2.77‰ for a Miocene sample in the overlying section. An average salinity of 21 to 25‰ was calculated for the Eocene Arctic, compared to 35‰ for the Miocene, with lower salinities during the Paleocene Eocene thermal maximum, the Azolla event at ˜48.7 Ma, and a third previously unidentified event at ˜47.6 Ma. At the Azolla event, where the organic carbon content of the sediment reaches a maximum, a positive δ13C excursion was observed, indicating unusually high productivity in the surface waters.

Free-radical concentrations and other properties of pile-irradiated coals

USGS Publications Warehouse

Friedel, R.A.; Breger, I.A.

1959-01-01

Five coals reacted quite differently when they were exposed to pile-irradiation. Little or no change was found in free-radical content for the three coals of lowest carbon content, whereas the two coals of highest carbon content were found to have a considerable increase in free-radical content. The infrared spectra and the apparent hardness of the irradiated coals of higher carbon content indicate that polymerization occurred. Radiation of these coals in chemical reagents may promote reactivity.

Aptian ‘Shale Gas’ Prospectivity in the Downdip Mississippi Interior Salt Basin, Gulf Coast, USA

USGS Publications Warehouse

Hackley, Paul C.; Valentine, Brett J.; Enomoto, Catherine B.; Lohr, Celeste D.; Scott, Krystina R.; Dulong, Frank T.; Bove, Alana M.

2016-01-01

This study evaluates regional ‘shale gas’ prospectivity of the Aptian section (primarily Pine Island Shale) in the downdip Mississippi Salt Basin (MSB). Previous work by the U.S. Geological Survey estimated a mean undiscovered gas resource of 8.8 trillion cubic feet (TCF) in the chronostratigraphic-equivalent Pearsall Formation in the Maverick Basin of south Texas, where industry has established a moderately successful horizontal gas and liquids play. Wells penetrating the downdip MSB Aptian section at depths of 12,000-15,000 ft were used to correlate formation tops in a 15-well cross-section extending about 200 miles (mi) east-southeastward from Adams Co. to Jackson Co. Legacy cuttings from these wells were analyzed for thermal maturity and source rock quality. Bitumen reflectance (n=53) increases with increasing present-day burial depth in the east-central study area from 1.0% to 1.7%. As the Aptian section shallows in Adams Co. to the west, bitumen Ro values are higher (1.7-2.0%), either from relatively greater heat flux or greater mid-Cenomanian uplift and erosion in this area. Total organic carbon (TOC) content ranges 0.01-1.21 and averages 0.5 wt.% (n=51); pyrolysis output (S2; n=51) averages 0.40 mg HC/g rock, indicating little present-day hydrocarbon-generative potential. Bitumen reflectance is preferred as a thermal maturity parameter as Tmax values are unreliable. Normalized X-ray diffraction (XRD) mineral analyses (n=26) indicate high average clay abundance (53 wt.%) relative to quartz (29%) and carbonate (18%). Mineral content shows a spatial relationship to an Appalachian orogen clastic sediment source, with proximal high clay and quartz and distal high carbonate content. Clastic influx from the Appalachian orogen is confirmed by detrital zircon U-Pb ages with dominant Grenville and Paleozoic components [105 ages from a Rodessa sandstone and 112 ages from a Paluxy (Albian) sandstone]. Preliminary information from fluid inclusion microthermometry (41 aqueous measurements from calcite cements in one argillaceous James Limestone sample) indicates homogenization temperatures (Th) of 120-135°C, consistent with present-day bottom-hole conditions and measured bitumen Ro values towards the western end of the MSB. Downdip in the central MSB, microthermometry (26 aqueous measurements from quartz dust rims in one Paluxy sandstone sample) and measured bitumen Ro values indicate maximum temperatures may have been significantly higher (~25°C) than present-day conditions. High inclusion salinities (15-25 wt.% salt) at both locations suggest interaction of pore fluids with evaporites. Mercury injection capillary pressure (MICP) analyses (n=3) indicate porosity ranges 1.3-2.1% and permeability 0.006-0.02 µD for Pine Island and Rodessa shales. Overall, results from this work indicate generally poor ‘shale gas’ prospectivity compared to other shale reservoirs based primarily on depth, low organic content, low porosity, and high clay content. However, thickness and thermal maturity are appropriate, moderate reservoir pressures are present, and petroleum systems modelling by others has indicated high undiscovered gas potential for the basin as a whole.

Microbial biocatalyst developments to upgrade fossil fuels.

PubMed

Kilbane, John J

2006-06-01

Steady increases in the average sulfur content of petroleum and stricter environmental regulations concerning the sulfur content have promoted studies of bioprocessing to upgrade fossil fuels. Bioprocesses can potentially provide a solution to the need for improved and expanded fuel upgrading worldwide, because bioprocesses for fuel upgrading do not require hydrogen and produce far less carbon dioxide than thermochemical processes. Recent advances have demonstrated that biodesulfurization is capable of removing sulfur from hydrotreated diesel to yield a product with an ultra-low sulfur concentration that meets current environmental regulations. However, the technology has not yet progressed beyond laboratory-scale testing, as more efficient biocatalysts are needed. Genetic studies to obtain improved biocatalysts for the selective removal of sulfur and nitrogen from petroleum provide the focus of current research efforts.

Patterns in Abundance, Cell Size and Pigment Content of Aerobic Anoxygenic Phototrophic Bacteria along Environmental Gradients in Northern Lakes

PubMed Central

Fauteux, Lisa; Cottrell, Matthew T.; Kirchman, David L.; Borrego, Carles M.; Garcia-Chaves, Maria Carolina; del Giorgio, Paul A.

2015-01-01

There is now evidence that aerobic anoxygenic phototrophic (AAP) bacteria are widespread across aquatic systems, yet the factors that determine their abundance and activity are still not well understood, particularly in freshwaters. Here we describe the patterns in AAP abundance, cell size and pigment content across wide environmental gradients in 43 temperate and boreal lakes of Québec. AAP bacterial abundance varied from 1.51 to 5.49 x 105 cells mL-1, representing <1 to 37% of total bacterial abundance. AAP bacteria were present year-round, including the ice-cover period, but their abundance relative to total bacterial abundance was significantly lower in winter than in summer (2.6% and 7.7%, respectively). AAP bacterial cells were on average two-fold larger than the average bacterial cell size, thus AAP cells made a greater relative contribution to biomass than to abundance. Bacteriochlorophyll a (BChla) concentration varied widely across lakes, and was not related to AAP bacterial abundance, suggesting a large intrinsic variability in the cellular pigment content. Absolute and relative AAP bacterial abundance increased with dissolved organic carbon (DOC), whereas cell-specific BChla content was negatively related to chlorophyll a (Chla). As a result, both the contribution of AAP bacteria to total prokaryotic abundance, and the cell-specific BChla pigment content were positively correlated with the DOC:Chla ratio, both peaking in highly colored, low-chlorophyll lakes. Our results suggest that photoheterotrophy might represent a significant ecological advantage in highly colored, low-chlorophyll lakes, where DOC pool is chemically and structurally more complex. PMID:25927833

Patterns in Abundance, Cell Size and Pigment Content of Aerobic Anoxygenic Phototrophic Bacteria along Environmental Gradients in Northern Lakes.

PubMed

Fauteux, Lisa; Cottrell, Matthew T; Kirchman, David L; Borrego, Carles M; Garcia-Chaves, Maria Carolina; Del Giorgio, Paul A

2015-01-01

There is now evidence that aerobic anoxygenic phototrophic (AAP) bacteria are widespread across aquatic systems, yet the factors that determine their abundance and activity are still not well understood, particularly in freshwaters. Here we describe the patterns in AAP abundance, cell size and pigment content across wide environmental gradients in 43 temperate and boreal lakes of Québec. AAP bacterial abundance varied from 1.51 to 5.49 x 105 cells mL-1, representing <1 to 37% of total bacterial abundance. AAP bacteria were present year-round, including the ice-cover period, but their abundance relative to total bacterial abundance was significantly lower in winter than in summer (2.6% and 7.7%, respectively). AAP bacterial cells were on average two-fold larger than the average bacterial cell size, thus AAP cells made a greater relative contribution to biomass than to abundance. Bacteriochlorophyll a (BChla) concentration varied widely across lakes, and was not related to AAP bacterial abundance, suggesting a large intrinsic variability in the cellular pigment content. Absolute and relative AAP bacterial abundance increased with dissolved organic carbon (DOC), whereas cell-specific BChla content was negatively related to chlorophyll a (Chla). As a result, both the contribution of AAP bacteria to total prokaryotic abundance, and the cell-specific BChla pigment content were positively correlated with the DOC:Chla ratio, both peaking in highly colored, low-chlorophyll lakes. Our results suggest that photoheterotrophy might represent a significant ecological advantage in highly colored, low-chlorophyll lakes, where DOC pool is chemically and structurally more complex.

High-Purity Composite Briquette for Direct UMG-Si Production in Arc Furnaces

NASA Astrophysics Data System (ADS)

Perruchoud, Raymond; Fischer, Jean-Claude

2013-12-01

In metallurgical grade Si (MG-Si), the coal (B) and charcoal (P) contents are on average above 30 ppm as the carbon reduction materials used in the arc furnace are either rich in B or in P. A decrease of both impurities by a factor of 3 using purer raw materials would allow for the direct production of the upgraded metallurgical grade (UMG).This would significantly improve the efficiency of the resulting photovoltaic (PV) cells made with the refined solar grade silicon (SoG-Si) or massively decrease the costs of Si purification by shortening the number of steps needed for reaching B and P contents below 1 ppm requested for the SoG-Si used for the PV cells. A composite C/SiO2 briquette fulfilling the purity targets for the direct production of UMG-Si in the arc furnace was developed. The composite contains several carbon materials with different levels of reactivities and quartz sand. The raw materials aspects, the paste and briquette preparation, as well as the final carbonization step are discussed. The finished briquettes are free of volatiles and are mechanically and thermally very stable, thus, ensuring stable arc furnace charges with minimum losses of dust and SiO gas. Semi-industrial trials including the downstream purification steps for the production of SoG-Si by a metallurgical low-cost route are contemplated.

Bottom sediments and nutrients in the tidal Potomac system, Maryland and Virginia

USGS Publications Warehouse

Glenn, Jerry L.

1988-01-01

The characteristics and distributions of near-surface bottom sediments and of nutrients in the sediments provide information on modern sediment and nutrient sources, sedimentation environments, and geochemical reactions in the tidal Potomac system, Maryland and Virginia. This information is fundamental to an improved understanding of sedimentation and eutrophication problems in the tidal Potomac system. The tidal Potomac system consists of 1,230 square kilometers of intertidal to subtidal Potomac mainstem and tributary streambed from the heads-of-tides to Chesapeake Bay. Tidal Potomac sediments are dominantly silt and clay except in local areas. An average sediment sample is about two-thirds silt and clay (fine) particles and one-third sand (coarse) particles. The mean of the median size of all samples is 6.60 phi, or 0.010 millimeters. Sorting generally is poor and the average sediment is skewed toward the fine tail of the size-distribution curve. Mean particle-size measures have large standard deviations. Among geomorphic units, two distinctly different size populations are found; fine (median phi about 9), and poorly sorted (sorting about 3) sediments in the channel and the smooth flat, and coarse (median phi about 2), and well sorted (sorting about 1) sediments in the shoreline flat and the irregular slope. Among mainstem hydrologic divisions, an average sediment from the river and the estuary division is coarser and more variable than an average sediment from the transition division. Substantial concentrations of total carbon, total nitrogen, and total phosphorus, and limited amounts of inorganic carbon, ammonia nitrogen and nitrite plus nitrate nitrogen occur in tidal Potomac sediments. An average tidal Potomac sediment sample weighing 1 kilogram contains about 21,000 milligrams of total carbon, 2,400 milligrams of total nitrogen, 1,200 milligrams of total phosphorus, 600 milligrams of inorganic carbon, 170 milligrams of ammonia nitrogen, and 2 milligrams of nitrite plus nitrate nitrogen. Total carbon, nitrogen, and phosphorus have an average ratio by weight of 18:2:1 and an average ratio by atoms of 94:8:1. Nutrient concentrations and nutrient ratios have large ranges and standard deviations. Nutrient concentrations usually are closely related to particle size; large concentrations are characteristic of fine sediments in the channel and the smooth flat, and small concentrations are typical of coarse sediments in the shoreline flat and the irregular slope. Concentrations typically decrease from the river division to the estuary division. Mainstem and tributaries show no statistically significant difference in mean particle-size measures or mean nutrient concentrations. Tributaries do not contribute large quantities of sediment with diverse texture or nutrient content to the Potomac mainstem. Particle-size measures and nutrient concentrations in the mainstem are significantly related to hydrologic divisions and geomorphic units; that is, particle size and nutrients vary significantly along and across the Potomac mainstem. Lateral variations in particle size and nutrient content are more pronounced and contribute more to significant relations than longitudinal variations contribute. The mean values for the median particle size and for the percentage of sand indicate significant variations among hydrologic divisions for samples from a geomorphic unit, and among geomorphic units, for samples from a hydrologic division. Sediments of channels and smooth flats in the river division commonly are coarser than sediments of channels and smooth flats in the transition and the estuary divisions. Shoreline flats in the estuary division are coarser than shoreline flats in the river division. Shoreline flats and irregular slopes in each hydrologic division generally are significantly coarser than channels and smooth flats. Relations between particle-size measures and geomorphic units show progressively larger cor

40 CFR 86.1865-12 - How to comply with the fleet average CO2 standards.

Code of Federal Regulations, 2013 CFR

2013-07-01

... different strategies are and why they are used. (i) Calculating the fleet average carbon-related exhaust emissions. (1) Manufacturers must compute separate production-weighted fleet average carbon-related exhaust... as defined in § 86.1818-12. The model type carbon-related exhaust emission results determined...

40 CFR 86.1865-12 - How to comply with the fleet average CO2 standards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... different strategies are and why they are used. (i) Calculating the fleet average carbon-related exhaust emissions. (1) Manufacturers must compute separate production-weighted fleet average carbon-related exhaust... as defined in § 86.1818-12. The model type carbon-related exhaust emission results determined...

40 CFR 86.1865-12 - How to comply with the fleet average CO2 standards.

Code of Federal Regulations, 2012 CFR

2012-07-01

... different strategies are and why they are used. (i) Calculating the fleet average carbon-related exhaust emissions. (1) Manufacturers must compute separate production-weighted fleet average carbon-related exhaust... as defined in § 86.1818-12. The model type carbon-related exhaust emission results determined...

Modelling and mapping the topsoil organic carbon content for Tanzania

NASA Astrophysics Data System (ADS)

Kempen, Bas; Kaaya, Abel; Ngonyani Mhaiki, Consolatha; Kiluvia, Shani; Ruiperez-Gonzalez, Maria; Batjes, Niels; Dalsgaard, Soren

2014-05-01

Soil organic carbon (SOC), held in soil organic matter, is a key indicator of soil health and plays an important role in the global carbon cycle. The soil can act as a net source or sink of carbon depending on land use and management. Deforestation and forest degradation lead to the release of vast amounts of carbon from the soil in the form of greenhouse gasses, especially in tropical countries. Tanzania has a high deforestation rate: it is estimated that the country loses 1.1% of its total forested area annually. During 2010-2013 Tanzania has been a pilot country under the UN-REDD programme. This programme has supported Tanzania in its initial efforts towards reducing greenhouse gas emission from forest degradation and deforestation and towards preserving soil carbon stocks. Formulation and implementation of the national REDD strategy requires detailed information on the five carbon pools among these the SOC pool. The spatial distribution of SOC contents and stocks was not available for Tanzania. The initial aim of this research, was therefore to develop high-resolution maps of the SOC content for the country. The mapping exercise was carried out in a collaborative effort with four Tanzanian institutes and data from the Africa Soil Information Service initiative (AfSIS). The mapping exercise was provided with over 3200 field observations on SOC from four sources; this is the most comprehensive soil dataset collected in Tanzania so far. The main source of soil samples was the National Forest Monitoring and Assessment (NAFORMA). The carbon maps were generated by means of digital soil mapping using regression-kriging. Maps at 250 m spatial resolution were developed for four depth layers: 0-10 cm, 10-20 cm, 20-30 cm, and 0-30 cm. A total of 37 environmental GIS data layers were prepared for use as covariates in the regression model. These included vegetation indices, terrain parameters, surface temperature, spectral reflectances, a land cover map and a small-scale Soil and Terrain (SOTER) map. Prediction uncertainty was quantified by the 90% prediction interval and the predictions were validated by cross-validation. The SOTER map proved to be the best predictor of SOC content, followed by the terrain parameters, mid-infrared reflectance, surface temperature, several vegetation indices, and the land cover map. The maps show that the SOC content decreases with depth, which is typically observed in soils. For the 0-10 cm layer the average predicted SOC content is 1.31%, for the 10-20 cm layer this is 0.93%, for the 20-30cm layer 0.72%, and for the 0-30cm layer 1.00%. The mean absolute error of the 0-10cm layer was 0.54%, that of the 10-20cm layer 0.38%, that of the 20-30cm layer 0.31%, and that of the 0-30cm layer 0.34%. The R2-value of the 0-10 cm layer was 0.47, that of the 10-20cm layer 0.49, that of the 20-30cm layer 0.44, and that of the 0-30cm layer 0.59. The next step will be the development of maps of SOC stock and key properties that are of interest for soil fertility management such as pH and the textural fractions.

Jellyfish Body Plans Provide Allometric Advantages beyond Low Carbon Content

PubMed Central

Pitt, Kylie A.; Duarte, Carlos M.; Lucas, Cathy H.; Sutherland, Kelly R.; Condon, Robert H.; Mianzan, Hermes; Purcell, Jennifer E.; Robinson, Kelly L.; Uye, Shin-Ichi

2013-01-01

Jellyfish form spectacular blooms throughout the world’s oceans. Jellyfish body plans are characterised by high water and low carbon contents which enables them to grow much larger than non-gelatinous animals of equivalent carbon content and to deviate from non-gelatinous pelagic animals when incorporated into allometric relationships. Jellyfish have, however, been argued to conform to allometric relationships when carbon content is used as the metric for comparison. Here we test the hypothesis that differences in allometric relationships for several key functional parameters remain for jellyfish even after their body sizes are scaled to their carbon content. Data on carbon and nitrogen contents, rates of respiration, excretion, growth, longevity and swimming velocity of jellyfish and other pelagic animals were assembled. Allometric relationships between each variable and the equivalent spherical diameters of jellyfish and other pelagic animals were compared before and after sizes of jellyfish were standardised for their carbon content. Before standardisation, the slopes of the allometric relationships for respiration, excretion and growth were the same for jellyfish and other pelagic taxa but the intercepts differed. After standardisation, slopes and intercepts for respiration were similar but excretion rates of jellyfish were 10× slower, and growth rates 2× faster than those of other pelagic animals. Longevity of jellyfish was independent of size. The slope of the allometric relationship of swimming velocity of jellyfish differed from that of other pelagic animals but because they are larger jellyfish operate at Reynolds numbers approximately 10× greater than those of other pelagic animals of comparable carbon content. We conclude that low carbon and high water contents alone do not explain the differences in the intercepts or slopes of the allometric relationships of jellyfish and other pelagic animals and that the evolutionary longevity of jellyfish and their propensity to form blooms is facilitated by their unique body plans. PMID:23967331

Jellyfish body plans provide allometric advantages beyond low carbon content.

PubMed

Pitt, Kylie A; Duarte, Carlos M; Lucas, Cathy H; Sutherland, Kelly R; Condon, Robert H; Mianzan, Hermes; Purcell, Jennifer E; Robinson, Kelly L; Uye, Shin-Ichi

2013-01-01

Jellyfish form spectacular blooms throughout the world's oceans. Jellyfish body plans are characterised by high water and low carbon contents which enables them to grow much larger than non-gelatinous animals of equivalent carbon content and to deviate from non-gelatinous pelagic animals when incorporated into allometric relationships. Jellyfish have, however, been argued to conform to allometric relationships when carbon content is used as the metric for comparison. Here we test the hypothesis that differences in allometric relationships for several key functional parameters remain for jellyfish even after their body sizes are scaled to their carbon content. Data on carbon and nitrogen contents, rates of respiration, excretion, growth, longevity and swimming velocity of jellyfish and other pelagic animals were assembled. Allometric relationships between each variable and the equivalent spherical diameters of jellyfish and other pelagic animals were compared before and after sizes of jellyfish were standardised for their carbon content. Before standardisation, the slopes of the allometric relationships for respiration, excretion and growth were the same for jellyfish and other pelagic taxa but the intercepts differed. After standardisation, slopes and intercepts for respiration were similar but excretion rates of jellyfish were 10× slower, and growth rates 2× faster than those of other pelagic animals. Longevity of jellyfish was independent of size. The slope of the allometric relationship of swimming velocity of jellyfish differed from that of other pelagic animals but because they are larger jellyfish operate at Reynolds numbers approximately 10× greater than those of other pelagic animals of comparable carbon content. We conclude that low carbon and high water contents alone do not explain the differences in the intercepts or slopes of the allometric relationships of jellyfish and other pelagic animals and that the evolutionary longevity of jellyfish and their propensity to form blooms is facilitated by their unique body plans.

Coastal landforms and accumulation of mangrove peat increase carbon sequestration and storage

PubMed Central

Garcillán, Pedro P.

2016-01-01

Given their relatively small area, mangroves and their organic sediments are of disproportionate importance to global carbon sequestration and carbon storage. Peat deposition and preservation allows some mangroves to accrete vertically and keep pace with sea-level rise by growing on their own root remains. In this study we show that mangroves in desert inlets in the coasts of the Baja California have been accumulating root peat for nearly 2,000 y and harbor a belowground carbon content of 900–34,00 Mg C/ha, with an average value of 1,130 (± 128) Mg C/ha, and a belowground carbon accumulation similar to that found under some of the tallest tropical mangroves in the Mexican Pacific coast. The depth–age curve for the mangrove sediments of Baja California indicates that sea level in the peninsula has been rising at a mean rate of 0.70 mm/y (± 0.07) during the last 17 centuries, a value similar to the rates of sea-level rise estimated for the Caribbean during a comparable period. By accreting on their own accumulated peat, these desert mangroves store large amounts of carbon in their sediments. We estimate that mangroves and halophyte scrubs in Mexico’s arid northwest, with less than 1% of the terrestrial area, store in their belowground sediments around 28% of the total belowground carbon pool of the whole region. PMID:27035950

Determining the bio-based content of bio-plastics used in Thailand by radiocarbon analysis

NASA Astrophysics Data System (ADS)

Ploykrathok, T.; Chanyotha, S.

2017-06-01

Presently, there is an increased interest in the development of bio-plastic products from agricultural materials which are biodegradable in order to reduce the problem of waste disposal. Since the amount of modern carbon in bio-plastics can indicate how much the amount of agricultural materials are contained in the bio-plastic products, this research aims to determine the modern carbon in bio-plastic using the carbon dioxide absorption method. The radioactivity of carbon-14 contained in the sample is measured by liquid scintillation counter (Tri-carb 3110 TR, PerkinElmer). The percentages of bio-based content in the samples were determined by comparing the observed modern carbon content with the values contained in agricultural raw materials. The experimental results show that only poly(lactic acid) samples have the modern carbon content of 97.4%, which is close to the agricultural materials while other bio-plastics types are found to have less than 50% of the modern carbon content. In other words, most of these bio-plastic samples were mixed with other materials which are not agriculturally originated.

Soil organic carbon response to shrub encroachment regulated by soil aggregates

NASA Astrophysics Data System (ADS)

Zhu, Y.; Li, H.; Shen, H.; Feng, Y.; Fang, J.

2017-12-01

Shrub encroachment leads to change in soil organic carbon content, but there still exists a lot of uncertainty in its mechanism as it relates to deep soil research. Soil organic carbon is usually associated with stable aggregate quantity. In this study, we conducted a field investigation for typical steppe and desert steppe in Inner Mongolia with the view to examining the impact of shrub encroachment on soil organic carbon with soil aggregate at a depth of 0-500 cm. The results show that in the desert steppe, the particle size of soil aggregate content level in different depth are presented the trend of shrub patches is lower than the herb matrix, organic carbon content of soil aggregate under 50 cm deeper presents the trend of shrub patches is higher than herb matrix, eventually leading to shrub patches whole soil organic carbon in the 0 to 50 cm depth lower than the herb matrix, and in deeper soil below 50 cm higher than the herb matrix. In the typical steppe, there is no significant difference between soil aggregate structure of shrub patches and herb matrix, but organic carbon content of soil aggregate, especially large aggregate organic carbon content in the shrub patches is significantly higher than the herb matrix, so that the whole soil organic carbon content in the shrub patches is significantly higher than herb matrix. The rate of soil organic carbon content change (0-100 cm) by shrub encroachment showed significant negative correlation with the mean weight diameter of soil aggregate of herb matrix. We also found that the variations of soil organic carbon in desert steppe is not dominant by aggregates of some size, but the change of the typical steppe soil organic carbon mainly contributed by > 0.25 mm and 0.053-0.25 mm aggregates. The results suggested that the effects of shrub encroachment on soil organic carbon is regulated by soil aggregate, but it is varied for different type of grassland, which should provide some insights into our understanding on regional carbon budget under global environment change.

Study of isotopes of carbon, thorium, and uranium in travertine and thermal spring samples: implications for effects of changes in geochemical environment and processes.

PubMed

Malov, Alexander I

2018-03-01

Data on modern radiocarbon activity in the old travertine formations of the Pymvashor hydrothermal system were used, in combination with 230 Th/U dating of the travertine, to estimate the 14 C contents of the total dissolved inorganic carbon in the ancient thermal water at the time of precipitation of the travertine ( 14 C calc ). With the known values of 14 C calc and average age of the thermal water, and under the assumption that the residence time of the water in aquifer was constant over the last 13.9 ± 1.5 ka, the initial 14 C contents ( 14 C 0 ) in the ancient thermal water were estimated. The findings in this study are that (1) both 14 C 0 and δ 13 С have decreased in young waters compared to the ancient waters; (2) although atmospheric 14 C activity ( 14 C atm ) has also decreased in the same time, the decrease in 14 C 0 is faster than the decrease in 14 C atm . Under certain assumptions, one could link changes in 14 C 0 and δ 13 C to climate change. Decrease in δ 13 С of soil CO 2 and decrease in 14 C 0 was caused predominantly by warmer and wetter climate, decomposition of fossil organic matter, and decrease in 14 C atm . There could be also increased dissolution of solid carbonate and increased carbon exchange between DIC and soil CO 2 , caused by thawing permafrost.

Microbial degradation of plant leachate alters lignin phenols and trihalomethane precursors

USGS Publications Warehouse

Pellerin, Brian A.; Hernes, Peter J.; Saraceno, John Franco; Spencer, Robert G.M.; Bergamaschi, Brian A.

2010-01-01

Although the importance of vascular plant-derived dissolved organic carbon (DOC) in freshwater systems has been studied, the role of leached DOC as precursors of disinfection byproducts (DBPs) during drinking water treatment is not well known. Here we measured the propensity of leachates from four crops and four aquatic macrophytes to form trihalomethanes (THMs)—a regulated class of DBPs—before and after 21 d of microbial degradation. We also measured lignin phenol content and specific UV absorbance (SUVA254) to test the assumption that aromatic compounds from vascular plants are resistant to microbial degradation and readily form DBPs. Leaching solubilized 9 to 26% of total plant carbon, which formed 1.93 to 6.72 mmol THM mol C-1 However, leachate DOC concentrations decreased by 85 to 92% over the 21-d incubation, with a concomitant decrease of 67 to 92% in total THM formation potential. Carbon-normalized THM yields in the residual DOC pool increased by 2.5 times on average, consistent with the preferential uptake of nonprecursor material. Lignin phenol concentrations decreased by 64 to 96% over 21 d, but a lack of correlation between lignin content and THM yields or SUVA254 suggested that lignin-derived compounds are not the source of increased THM precursor yields in the residual DOC pool. Our results indicate that microbial carbon utilization alters THM precursors in ecosystems with direct plant leaching, but more work is needed to identify the specific dissolved organic matter components with a greater propensity to form DBPs and affect watershed management, drinking water quality, and human health.

7 CFR 51.2561 - Average moisture content.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Average moisture content. 51.2561 Section 51.2561... STANDARDS) United States Standards for Grades of Shelled Pistachio Nuts § 51.2561 Average moisture content. (a) Determining average moisture content of the lot is not a requirement of the grades, except when...

Biomass fuel use and indoor air pollution in homes in Malawi

PubMed Central

Fullerton, D G; Semple, S; Kalambo, F; Suseno, A; Malamba, R; Henderson, G; Ayres, J G; Gordon, S B

2009-01-01

Background: Air pollution from biomass fuels in Africa is a significant cause of mortality and morbidity both in adults and children. The work describes the nature and quantity of smoke exposure from biomass fuel in Malawian homes. Methods: Markers of indoor air quality were measured in 62 homes (31 rural and 31 urban) over a typical 24 h period. Four different devices were used (one gravimetric device, two photometric devices and a carbon monoxide (HOBO) monitor. Gravimetric samples were analysed for transition metal content. Data on cooking and lighting fuel type together with information on indicators of socioeconomic status were collected by questionnaire. Results: Respirable dust levels in both the urban and rural environment were high with the mean (SD) 24 h average levels being 226 μg/m3 (206 μg/m3). Data from real-time instruments indicated respirable dust concentrations were >250 μg/m3 for >1 h per day in 52% of rural homes and 17% of urban homes. Average carbon monoxide levels were significantly higher in urban compared with rural homes (6.14 ppm vs 1.87 ppm; p<0.001). The transition metal content of the smoke was low, with no significant difference found between urban and rural homes. Conclusions: Indoor air pollution levels in Malawian homes are high. Further investigation is justified because the levels that we have demonstrated are hazardous and are likely to be damaging to health. Interventions should be sought to reduce exposure to concentrations less harmful to health. PMID:19671533

Microstructure and Mechanical Properties of Reaction-Formed Silicon Carbide (RFSC) Ceramics

NASA Technical Reports Server (NTRS)

Singh, M.; Behrendt, D. R.

1994-01-01

The microstructure and mechanical properties of reaction-formed silicon carbide (RFSC) ceramics fabricated by silicon infiltration of porous carbon preforms are discussed. The morphological characterization of the carbon preforms indicates a very narrow pore size distribution. Measurements of the preform density by physical methods and by mercury porosimetry agree very well and indicate that virtually all of the porosity in the preforms is open to infiltrating liquids. The average room temperature flexural strength of the RFSC material with approximately 8 at.% free silicon is 369 +/- 28 MPa (53.5 +/- 4 ksi). The Weibull strength distribution data give a characteristic strength value of 381 MPa (55 ksi) and a Weibull modulus of 14.3. The residual silicon content is lower and the strengths are superior to those of most commercially available reaction-bonded silicon carbide materials.

40 CFR 86.1865-12 - How to comply with the fleet average CO2 standards.

Code of Federal Regulations, 2014 CFR

2014-07-01

...) Calculating the fleet average carbon-related exhaust emissions. (1) Manufacturers must compute separate production-weighted fleet average carbon-related exhaust emissions at the end of the model year for passenger... for sale, and certifying model types to standards as defined in § 86.1818-12. The model type carbon...

[Effects of cotton straw returning on soil organic carbon, nitrogen, phosphorus and potas-sium contents in soil aggregates].

PubMed

Wang, Shuang Lei; Liu, Yan Hui; Song, Xian Liang; Wei, Shao Bin; Li, Jin Pu; Nie, Jun Jun; Qin, Du Lin; Sun, Xue Zhen

2016-12-01

To clarify the effects of cotton straw returning on the composition and contents of nu-trients in different particle sizes of aggregates, two treatments with or without cotton straw returning were tested in continuous three years. After three years straw treatments, we collected undisturbed soil within 0-5, 5-10, 10-20 and 20-30 cm soil layers, and to measure the composition, soil organic carbon, nitrogen, phosphorus and potassium contents in different particle sizes of aggregates classified using dry sieving. Returning cotton straw into the field significantly increased particle contents of 2-5 mm and >5 mm aggregates in 0-5 cm soil layer, while the content of <0.25 mm micro-aggregates was decreased. Cotton straw returning significantly improved soil organic carbon, nitrogen, and potassium contents by 19.2%, 14.2% and 17.3%, respectively, compared to no returning control. In 5-10 cm soil layer, cotton straw returning increased the contents of 2-5 mm and >5 mm aggregates, reduced the content of <0.25 mm micro-aggregate, but significantly increased contents of soil organic carbon, available nitrogen and potassium by 19.6%, 12.6% and 23.4%, compared to no straw returning control. In 10-20 cm soil layer, cotton straw returning significantly reduced the content of <0.25 mm micro-aggregates, and significantly enhanced soil organic carbon, nitrogen, and potassium contents by 8.4%, 10.9% and 11.5%, compared to the control. However, in 20-30 cm soil layer, cotton straw returning only increased soil available potassium content by 12.0%, while there were no significant changes in particle size, organic carbon, nitrogen and phosphorus contents. We concluded that cotton straw returning could significantly improve the structure of surface soil by increasing the number of macro-aggregates, contents of organic carbon, available nitrogen and potassium in aggregates, while decreasing micro-aggregate content. The enhancement of the contribution of macro-aggregates to soil fertility by returning cotton straw could improve soil physical structure, fertility and then increase cotton yield.

[Effects of tree species fine root decomposition on soil active organic carbon].

PubMed

Liu, Yan; Wang, Si-Long; Wang, Xiao-Wei; Yu, Xiao-Jun; Yang, Yue-Jun

2007-03-01

With incubation test, this paper studied the effects of fine root decomposition of Alnus cremastogyne, Cunninghamia lanceolata and Michelia macclurei on the content of soil active organic carbon at 9 degrees C , 14 degrees C , 24 degrees C and 28 degrees C. The results showed that the decomposition rate of fine root differed significantly with test tree species, which was decreased in the order of M. macclurei > A. cremastogyne > C. lanceolata. The decomposition rate was increased with increasing temperature, but declined with prolonged incubation time. Fine root source, incubation temperature, and incubation time all affected the contents of soil microbial biomass carbon and water-soluble organic carbon. The decomposition of fine root increased soil microbial biomass carbon and water-soluble organic carbon significantly, and the effect decreased in the order of M. macclurei > A. cremastogyne > C. lanceolata. Higher contents of soil microbial biomass carbon and water-soluble organic carbon were observed at medium temperature and middle incubation stage. Fine root decomposition had less effect on the content of soil readily oxidized organic carbon.

Comparison of organic geochemistry and metal enrichment in two black shales: Cambrian Alum Shale of Sweden and Devonian Chattanooga Shale of United States

USGS Publications Warehouse

Leventhal, J.S.

1991-01-01

In most black shales, such as the Chattanooga Shale and related shales of the eastern interior United States, increased metal and metalloid contents are generally related to increased organic carbon content, decreased sedimentation rate, organic matter type, or position in the basin. In areas where the stratigraphic equivalents of the Chattanooga Shale are deeply buried and and the organic material is thermally mature, metal contents are essentially the same as in unheated areas and correlate with organic C or S contents. This paradigm does not hold for the Cambrian Alum Shale Formation of Sweden where increased metal content does not necessarily correlate with organic matter content nor is metal enrichment necessarily related to land derived humic material because this organic matter is all of marine source. In southcentral Sweden the elements U, Mo, V, Ni, Zn, Cd and Pb are all enriched relative to average black shales but only U and Mo correlate to organic matter content. Tectonically disturbed and metamorphosed allochthonous samples of Alum Shale on the Caledonian front in western Sweden have even higher amounts for some metals (V, Ni, Zn and Ba) relative to the autochthonous shales in this area and those in southern Sweden. ?? 1991 Springer-Verlag.

Soil Organic Carbon Pools and Stocks in Permafrost-Affected Soils on the Tibetan Plateau

PubMed Central

Dörfer, Corina; Kühn, Peter; Baumann, Frank; He, Jin-Sheng; Scholten, Thomas

2013-01-01

The Tibetan Plateau reacts particularly sensitively to possible effects of climate change. Approximately two thirds of the total area is affected by permafrost. To get a better understanding of the role of permafrost on soil organic carbon pools and stocks, investigations were carried out including both discontinuous (site Huashixia, HUA) and continuous permafrost (site Wudaoliang, WUD). Three organic carbon fractions were isolated using density separation combined with ultrasonic dispersion: the light fractions (<1.6 g cm−3) of free particulate organic matter (FPOM) and occluded particulate organic matter (OPOM), plus a heavy fraction (>1.6 g cm−3) of mineral associated organic matter (MOM). The fractions were analyzed for C, N, and their portion of organic C. FPOM contained an average SOC content of 252 g kg−1. Higher SOC contents (320 g kg−1) were found in OPOM while MOM had the lowest SOC contents (29 g kg−1). Due to their lower density the easily decomposable fractions FPOM and OPOM contribute 27% (HUA) and 22% (WUD) to the total SOC stocks. In HUA mean SOC stocks (0–30 cm depth) account for 10.4 kg m−2, compared to 3.4 kg m−2 in WUD. 53% of the SOC is stored in the upper 10 cm in WUD, in HUA only 39%. Highest POM values of 36% occurred in profiles with high soil moisture content. SOC stocks, soil moisture and active layer thickness correlated strongly in discontinuous permafrost while no correlation between SOC stocks and active layer thickness and only a weak relation between soil moisture and SOC stocks could be found in continuous permafrost. Consequently, permafrost-affected soils in discontinuous permafrost environments are susceptible to soil moisture changes due to alterations in quantity and seasonal distribution of precipitation, increasing temperature and therefore evaporation. PMID:23468904

[Distribution of soil organic carbon, total nitrogen, total phosphorus and water stable aggregates of cropland with different soil textures on the Loess Plateau, Northwest China].

PubMed

Ge, Nan Nan; Shi, Yun; Yang, Xian Long; Zhang, Qing Yin; Li, Xue Zhang; Jia, Xiao Xu; Shao, Ming An; Wei, Xiao Rong

2017-05-18

In this study, combined with field investigation and laboratory analyses, we assessed the distribution of soil organic carbon, nitrogen, phosphorous contents and their stoichiometric ratios, and the distribution of soil water stable aggregates along a soil texture gradient in the cropland of the Loess Plateau to understand the effect of soil texture and the regulation of soil aggregates on soil fertility in cropland. The results showed that, with the change from fine soils to coarse soils along the texture gradient (loam clay→ clay loam→ sandy loam), the contents of macroaggregates, organic carbon, nitrogen, phosphorous and their stoichiometric ratios decreased, while pH value and microaggregates content showed an opposite changing pattern. The contents of macroaggregates, organic carbon, nitrogen, phosphorous, and C/P and N/P were significantly increased, but pH value and microaggregates content were significantly decreased with increasing the soil clay content. Furthermore, the contents of organic carbon, nitrogen, phosphorous, and C/P and N/P increased with the increase of macroaggregates content. These results indicated that soil fertility in croplands at a regional scale was mainly determined by soil texture, and was regulated by soil macroaggregates.

Quantitative solid-state 13C nuclear magnetic resonance spectrometric analyses of wood xylen: effect of increasing carbohydrate content

USGS Publications Warehouse

Bates, A.L.; Hatcher, P.G.

1992-01-01

Isolated lignin with a low carbohydrate content was spiked with increasing amounts of alpha-cellulose, and then analysed by solid-state 13C nuclear magnetic resonance (NMR) using cross-polarization with magic angle spinning (CPMAS) and dipolar dephasing methods in order to assess the quantitative reliability of CPMAS measurement of carbohydrate content and to determine how increasingly intense resonances for carbohydrate carbons affect calculations of the degree of lignin's aromatic ring substitution and methoxyl carbon content. Comparisons were made of the carbohydrate content calculated by NMR with carbohydrate concentrations obtained by phenol-sulfuric acid assay and by the calculation from the known amounts of cellulose added. The NMR methods used in this study yield overestimates for carbohydrate carbons due to resonance area overlap from the aliphatic side chain carbons of lignin. When corrections are made for these overlapping resonance areas, the NMR results agree very well with results obtained by other methods. Neither the calculated methoxyl carbon content nor the degree of aromatic ring substitution in lignin, both calculated from dipolar dephasing spectra, change with cellulose content. Likewise, lignin methoxyl content does not correlate with cellulose abundance when measured by integration of CPMAS spectra. ?? 1992.

Topsoil organic carbon content of Europe, a new map based on a generalised additive model

NASA Astrophysics Data System (ADS)

de Brogniez, Delphine; Ballabio, Cristiano; Stevens, Antoine; Jones, Robert J. A.; Montanarella, Luca; van Wesemael, Bas

2014-05-01

There is an increasing demand for up-to-date spatially continuous organic carbon (OC) data for global environment and climatic modeling. Whilst the current map of topsoil organic carbon content for Europe (Jones et al., 2005) was produced by applying expert-knowledge based pedo-transfer rules on large soil mapping units, the aim of this study was to replace it by applying digital soil mapping techniques on the first European harmonised geo-referenced topsoil (0-20 cm) database, which arises from the LUCAS (land use/cover area frame statistical survey) survey. A generalized additive model (GAM) was calibrated on 85% of the dataset (ca. 17 000 soil samples) and a backward stepwise approach selected slope, land cover, temperature, net primary productivity, latitude and longitude as environmental covariates (500 m resolution). The validation of the model (applied on 15% of the dataset), gave an R2 of 0.27. We observed that most organic soils were under-predicted by the model and that soils of Scandinavia were also poorly predicted. The model showed an RMSE of 42 g kg-1 for mineral soils and of 287 g kg-1 for organic soils. The map of predicted OC content showed the lowest values in Mediterranean countries and in croplands across Europe, whereas highest OC content were predicted in wetlands, woodlands and in mountainous areas. The map of standard error of the OC model predictions showed high values in northern latitudes, wetlands, moors and heathlands, whereas low uncertainty was mostly found in croplands. A comparison of our results with the map of Jones et al. (2005) showed a general agreement on the prediction of mineral soils' OC content, most probably because the models use some common covariates, namely land cover and temperature. Our model however failed to predict values of OC content greater than 200 g kg-1, which we explain by the imposed unimodal distribution of our model, whose mean is tilted towards the majority of soils, which are mineral. Finally, average OC content predictions for each land cover class compared well between models, with our model always showing smaller standard deviations. We concluded that the chosen model and covariates are appropriate for the prediction of OC content in European mineral soils. We presented in this work the first map of topsoil OC content at European scale based on a harmonised soil dataset. The associated uncertainty map shall support the end-users in a careful use of the predictions.

Partitioning of carbon between Fe-rich alloy melt and silicate melt in a magma ocean - Implications for the abundance and origin of volatiles in Earth, Mars, and the Moon

NASA Astrophysics Data System (ADS)

Chi, Han; Dasgupta, Rajdeep; Duncan, Megan S.; Shimizu, Nobumichi

2014-08-01

The budget and origin of carbon in Earth and other terrestrial planets are debated and one of the key unknowns is the fate of carbon during early planetary processes including accretion, core formation, and magma ocean (MO) crystallization. Here we determine, experimentally, the solubility of carbon in coexisting Fe-Ni alloy melt and basaltic silicate melt in shallow MO conditions, i.e., at 1-3 GPa, 1500-1800 °C. Oxygen fugacity of the experiments, estimated based on Fe (in metallic alloy melt)-FeO (in silicate melt) equilibrium, varied between ∼IW-0.4 and IW-1.0, where IW refers to the oxygen fugacity imposed by the coexistence of iron and wüstite. Four different starting mixes, each with 7:3 silicate:metal mass ratio and silicate melt NBO/T (estimated proportion of non-bridging oxygen with respect to tetrahedral cations; NBO/T=2×/total OT -4, where T = Si + Ti + Al + Cr + P) ranging from 0.81 to 1.54 were studied. Concentrations of carbon in the alloy melt were determined using electron microprobe whereas carbon contents of quenched basaltic glasses were determined using secondary ionization mass spectrometry (SIMS). Identification of carbon and hydrogen-bearing species in silicate glasses was performed using Raman and Fourier Transformed Infrared (FTIR) spectroscopy. Our results show that carbon in the metallic melt varies between 4.4 wt.% and 7.4 wt.% and increases with increasing temperature and modestly with increasing pressure but decreases with increasing Ni content of the alloy melt. Carbon concentration in the silicate melts, on the other hand, varies from 11 ± 1 ppm to 111 ± 7 ppm and is negatively correlated with pressure but positively correlated with temperature, the NBO/T, the oxygen fugacity and the water content of the silicate melts. Raman and FTIR results show that at our experimental conditions, carbon in silicate melt is dissolved both as hydrogenated species and CO32-. The calculated carbon partition coefficient DCmetal/silicate varies from 510 ± 53 to 5369 ± 217 and varies systematically as a function of P, T, fO2, water content, the composition of the silicate melt (expressed using NBO/T), and Ni content of alloy melt (XNi). The range of DCmetal/silicate measured in our study with carbonated and hydrogenated carbon species in silicate melt is similar to that reported in the literature for experiments where carbonyl complexes are the chief carbon species in silicate melts. A parameterization was derived using the data from this and existing studies such as lnDCmetal/silicate=a/T+b·P/T+c·ln(fO2)+d·(NBO/T)+e·ln(1-XNi)+f where a = -33,510, b = 1357, c = -0.596, d = -1.182, e = 4.15, f = 13.38, the temperature is in Kelvin, and the pressure is in gigapascal. Using this parameterization and the estimated conditions for the base of the MOs, the average DCmetal/silicate value for Earth, Mars, and the Moon can be predicted. The deep MO of Earth is predicted to cause the strongest depletion of its silicate carbon budget, closely followed by Mars with intermediate depth MO, and then the Moon with a shallow MO. We predict that the lunar mantle carbon budget, similar to that of the Earth’s present-day upper mantle, might have been set by equilibrium core-mantle fractionation in MO; whereas for Earth, later processes such as ingassing from a proto-atmosphere and late-stage accretion of volatile-rich material was necessary for delivery of carbon and other volatiles. Finally, the comparison of our measured and predicted value of DCmetal/silicate for terrestrial MO with similar constraints on DNmetal/silicate from the literature suggests that the apparent depletion of nitrogen relative to carbon for the bulk silicate Earth and the Earth’s upper mantle is unlikely to be caused by preferential partitioning of nitrogen to alloy melt during core formation.

Nitrogen-Containing Carbon Nanotube Synthesized from Polymelem and Activated Carbon Derived from Polymer Blend

NASA Astrophysics Data System (ADS)

Qin, Nan

Polymelem possesses a polymeric structure of heptazine (C6N 7) rings connected by amine bridges and our study has demonstrated that it is a promising precursor for the synthesis of nitrogen-containing carbon materials. Nitrogen-containing carbon nanotube (NCNT) was produced by pyrolyzing polymelem as a dual source of carbon and nitrogen with Raney nickel in a high pressure stainless steel cell. Activated carbon was produced from poly(ether ether ketone)/poly(ether imide) (PEEK/PEI blend) and incorporated with polymelem to enhance the hydrogen adsorption. Polymelem was successfully synthesized by pyrolyzing melamine at 450--650 °C and its structure was elucidated by 13C solid state NMR, FTIR, and XRD. The molecular weight determined by a novel LDI MS equipped with a LIFT mode illuminated that polymelem has both linear and cyclic connectivity with a degree of polymerization of 2--5 depending on the synthesis temperature. The decomposition products of polymelem were determined to be cyanoamide, dicyanoamide, and tricyanoamine. Tricyanoamine is the smallest carbon nitride molecule and has been experimentally confirmed for the first time in this study. When polymelem was decomposed in the presence of Raney nickel, homogenous NCNT with nitrogen content of ˜ 4--19 atom% was produced. A mechanism based on a detail analysis of the TEM images at different growth stages proposed that the NCNT propagated via a tip-growth mechanism originating at the nano-domains within the Raney nickel, and was accompanied with the aggregation of the nickel catalysts. Such NCNT exhibited a cup-stack wall structure paired with a compartmental feature. The nitrogen content, tube diameter and wall thickness greatly depended on synthesis conditions. The activated carbon derived from PEEK/PEI blend demonstrated a surface area up to ˜3000 m2/g, and average pore size of < 20 A. Such activated carbon exhibited a hydrogen storage capacity of up to 6.47 wt% at 40 bar, 77 K. The activated carbon has was incorporated with polymelem via a liquid penetration and a CVD method to modify its surface chemistry. The hydrogen adsorption energy of the polymelem doped activated carbon demonstrated a dramatic increase from ˜5 kJ/mol to ˜14 kJ/mol due to the higher polarizability of the polymelem.

Carbonatite tuffs in the Laetolil Beds of Tanzania and the Kaiserstuhl in Germany

USGS Publications Warehouse

Hay, R.L.; O'Neil, J.R.

1983-01-01

Carbonatite lava and tephra are now well known. The only modern eruptive carbonatites, from Oldoinyo Lengai, Tanzania, are of alkali carbonatite, whereas all of the pre-modern examples are of calcite or dolomite. Chemical and stable isotope analyses were made of separate phases of Pliocene carbonatite tuffs of the Laetolil Beds in Tanzania and of Miocene carbonatite tuffs of the Kaiserstuhl in Germany in order to understand the reasons for this major difference. The Laetolil Beds contain numerous carbonatite and melilitite-carbonatite tuffs. It is proposed that the carbonatite ash was originally of alkali carbonate composition and that the alkali component was dissolved, leaving a residuum of calcium carbonate. The least recrystallized melilitite-carbonatite tuff contains early-deposited calcite cement and calcite pseudomorphs after nyerereite (?) that have contents of strontium and barium and ??18O and ??13C values suggestive of incomplete chemical and isotopic exchange during alteration and replacement of alkali carbonatite ash. Carbonatite tuffs of the Kaiserstuhl contain globules composed of calcite phenocrysts and microphenocrysts in a groundmass of calcite with a small amount of clay, apatite, and magnetite. The SrO contents of phenocrysts, microphenocrysts, and groundmass calcite average 0.90, 1.42, and 0.59 percent, respectively. The average ??18O and ??13C values of globules (+14.3 and -9.0, respectively) fall between those of coarse-grained intrusive Kaiserstuhl carbonatite (avg. +6.6, -5.8) and those of low-temperature calcite cement in the carbonatite tuffs (+21.8, -14.9). The phenocrysts and microphenocrysts are primary magmatic calcite, but several features indicate that the groundmass has been recrystallized and altered in contact with meteoric water, resulting in weathering of silicate to clay, leaching of strontium, and isotopic exchange. The weight of evidence favors an original high content of alkali carbonatite in the groundmass, with recrystallization following leaching of the alkalies. ?? 1983 Springer-Verlag.

Evaluation of gastrointestinal solubilization of petroleum hydrocarbon residues in soil using an in vitro physiologically based model.

PubMed

Holman, Hoi-Ying N; Goth-Goldstein, Regine; Aston, David; Yun, Mao; Kengsoontra, Jenny

2002-03-15

Petroleum hydrocarbon residues in weathered soils may pose risks to humans through the ingestion pathway. To understand the factors controlling their gastrointestinal (GI) absorption, a newly developed experimental extraction protocol was used to model the GI solubility of total petroleum hydrocarbon (TPH) residues in highly weathered soils from different sites. The GI solubility of TPH residues was significantly higher for soil contaminated with diesel than with crude oil. Compared to the solubility of TPH residues during fasted state,the solubility of TPH residues during fat digestion was much greater. Diesel solubility increased from an average of 8% during the "gallbladder empty" phase of fasting (and less than 0.2% during the otherfasting phase) to an average of 16% during fat digestion. For crude oil, the solubility increased from an average of 1.2% during the gallbladder empty phase of fasting (and undetectable during the other fasting phase) to an average of 4.5% during fat digestion. Increasing the concentration of bile salts also increased GI solubility. GI solubility was reduced by soil organic carbon but enhanced by the TPH content.

Sequential ASE extraction of alkylphenols from sediments: Occurrence and environmental implications.

PubMed

Gong, Jian; Xu, Lei; Yang, Yu; Chen, Di-Yun; Ran, Yong

2011-08-30

The occurrence of alkylphenols (APs) including nonylphenol (NP) and octylphenol (OP) in the riverine sediments from the Pearl River Delta (PRD), South China was investigated and compared by Soxhlet extraction (S-APs) with dichloromethane and by sequential accelerated solvent extraction (ASE) (A-APs) with 1:6 toluene/methanol, respectively. Concentrations of OP and NP range from <1 to 463ng/g dw and 31-21,885ng/g dw, respectively, demonstrating that the contamination level of APs in the PRD is one of the highest in the world. Moreover, the A-APs contents are highly significantly related to and on average 1.5 times the S-APs contents. For sequential two ASE extractions, APs in the first extract accounts for 82.2-99.2% of their total contents in the sequential two extractions. The correlation analysis shows that S-APs and A-APs are both significantly associated with the contents of total organic carbon (TOC), suggesting that the variable extraction efficiency of these two methods is related to the presence of condensed organic matter in the sediments. Copyright © 2011 Elsevier B.V. All rights reserved.

Effect of 26 Years of Intensively Managed Carya cathayensis Stands on Soil Organic Carbon and Fertility

PubMed Central

Wu, Jiasen; Huang, Jianqin; Liu, Dan; Li, Jianwu; Zhang, Jinchi; Wang, Hailong

2014-01-01

Chinese hickory (Carya cathayensis), a popular nut food tree species, is mainly distributed in southeastern China. A field study was carried out to investigate the effect of long-term intensive management on fertility of soils under a C. cathayensis forest. Results showed that after 26 years' intensive management, the soil organic carbon (SOC) content of the A and B horizons reduced by 19% and 14%, respectively. The reduced components of SOC are mainly the alkyl C and O-alkyl C, whereas the aromatic C and carbonyl C remain unchanged. The reduction of active organic matter could result in degradation of soil fertility. The pH value of soil in the A horizon had dropped by 0.7 units on average. The concentrations of the major nutrients also showed a decreasing trend. On average the concentrations of total nitrogen (N), phosphorus (P), and potassium (K) of tested soils dropped by 21.8%, 7.6%, and 13.6%, respectively, in the A horizon. To sustain the soil fertility and C. cathayensis production, it is recommended that more organic fertilizers (manures) should be used together with chemical fertilizers. Lime should also be applied to reduce soil acidity. PMID:24558339

Effect of 26 years of intensively managed Carya cathayensis stands on soil organic carbon and fertility.

PubMed

Wu, Jiasen; Huang, Jianqin; Liu, Dan; Li, Jianwu; Zhang, Jinchi; Wang, Hailong

2014-01-01

Chinese hickory (Carya cathayensis), a popular nut food tree species, is mainly distributed in southeastern China. A field study was carried out to investigate the effect of long-term intensive management on fertility of soils under a C. cathayensis forest. Results showed that after 26 years' intensive management, the soil organic carbon (SOC) content of the A and B horizons reduced by 19% and 14%, respectively. The reduced components of SOC are mainly the alkyl C and O-alkyl C, whereas the aromatic C and carbonyl C remain unchanged. The reduction of active organic matter could result in degradation of soil fertility. The pH value of soil in the A horizon had dropped by 0.7 units on average. The concentrations of the major nutrients also showed a decreasing trend. On average the concentrations of total nitrogen (N), phosphorus (P), and potassium (K) of tested soils dropped by 21.8%, 7.6%, and 13.6%, respectively, in the A horizon. To sustain the soil fertility and C. cathayensis production, it is recommended that more organic fertilizers (manures) should be used together with chemical fertilizers. Lime should also be applied to reduce soil acidity.

Influence of the overfire air ratio on the NO(x) emission and combustion characteristics of a down-fired 300-MW(e) utility boiler.

PubMed

Ren, Feng; Li, Zhengqi; Chen, Zhichao; Fan, Subo; Liu, Guangkui

2010-08-15

Down-fired boilers used to burn low-volatile coals have high NO(x) emissions. To find a way of solving this problem, an overfire air (OFA) system was introduced on a 300 MW(e) down-fired boiler. Full-scale experiments were performed on this retrofitted boiler to explore the influence of the OFA ratio (the mass flux ratio of OFA to the total combustion air) on the combustion and NO(x) emission characteristics in the furnace. Measurements were taken of gas temperature distributions along the primary air and coal mixture flows, average gas temperatures along the furnace height, concentrations of gases such as O(2), CO, and NO(x) in the near-wall region and carbon content in the fly ash. Data were compared for five different OFA ratios. The results show that as the OFA ratio increases from 12% to 35%, the NO(x) emission decreases from 1308 to 966 mg/Nm(3) (at 6% O(2) dry) and the carbon content in the fly ash increases from 6.53% to 15.86%. Considering both the environmental and economic effect, 25% was chosen as the optimized OFA ratio.

The effect of aromatization on the isotopic compositions of hydrocarbons during early diagenesis

NASA Technical Reports Server (NTRS)

Freeman, K. H.; Boreham, C. J.; Summons, R. E.; Hayes, J. M.

1994-01-01

Polycyclic aromatic hydrocarbons with varying degrees of aromatization were isolated from the Eocene Messel Shale (Rheingraben, Germany). The high abundances of these compounds and their structural resemblances to cyclic triterpenoid lipids are consistent with derivation from microbial rather than thermal processes. Compounds structurally related to oleanane contain from five to nine double bonds; those within a series of aromatized hopanoids contain from three to nine. All are products of diagenetic reactions that remove hydrogen or methyl groups, and, in several cases, break carbon-carbon bonds to open rings. Aromatized products are on average depleted in 13C relative to possible precursors by l.2% (range: l.5% enrichment to 4% depletion, n = 9). The dependence of 13C content on the number of double bonds is not, however, statistically significant and it must be concluded that there is no strong evidence for isotopic fractionation accompanying diagenetic aromatization. Isotopic differences between series (structures related to ursane, des-A-ursane, des-A-lupane, des-A-arborane, and possibly, des-A-gammacerane are present) are much greater, indicating that 13C contents are controlled primarily by source effects. Fractionations due to chromatographic isotope effects during HPLC ranged from 0.1 to 2.8%.

Evaluating the effectiveness of mulch application to store carbon belowground: Short-term effects of mulch application on soluble soil and microbial C and N in agricultural soils with low and high organic matter

NASA Astrophysics Data System (ADS)

Chen, Janet; Heiling, Maria; Resch, Christian; Gruber, Roman; Dercon, Gerd

2017-04-01

Agricultural soils have the potential to contain a large pool of carbon and, depending on the farming techniques applied, can either effectively store carbon belowground, or further release carbon, in the form of CO2, into the atmosphere. Farming techniques, such as mulch application, are frequently proposed to increase carbon content belowground and improve soil quality and can be used in efforts to reduce greenhouse gas levels, such as in the "4 per 1000" Initiative. To test the effectiveness of mulch application to store carbon belowground in the short term and improve soil nutrient quality, we maintained agricultural soils with low and high organic carbon content (disturbed top soil from local Cambisols and Chernozems) in greenhouse mesocosms (70 cm deep with a radius of 25 cm) with controlled moisture for 4 years. Over the 4 years, maize and soybean were grown yearly in rotation and mulch was removed or applied to soils once plant material was harvested at 2 ton/ha dry matter. In addition, soil disturbance was kept to a minimum, with only surface disturbance of a few centimeters to keep soil free from weeds. After 4 years, we measured effects of mulch application on soluble soil and microbial carbon and nitrogen in the mesocosms and compared effects of mulch application versus no mulch on soils from 0-5 cm and 5-15 cm with low and high organic matter. We predicted that mulch would increase soil carbon and nitrogen content and mulch application would have a greater effect on soils with low organic matter than soils with high organic matter. In soils with low organic carbon content and larger predicted potential to increase soil carbon, mulch application did not increase soluble soil or microbial carbon or nitrogen compared to the treatments without mulch application. However, mulch application significantly increased the δ13C of both microbial and soluble soil carbon in these soils by 1 ‰ each, indicating a shift in belowground processes, such as increased decomposition coupled with increased carbon inputs. In soils with more organic content and lower potential to increase soil carbon, mulch application decreased microbial carbon by 0.01 mg C g soil-1 and increased soluble soil nitrogen by 0.01 mg N g soil-1. Soluble soil carbon also decreased by 0.04 mg C g soil-1 and microbial nitrogen increased with mulch application by 0.006 mg N g soil-1, but only in 5-15 cm soil. Mulch application only decreased δ13C of soluble soil carbon by 1.5 ‰, likely indicating a decrease in decomposition. Contrary to our initial predictions, mulch did not increase soil carbon content and only increased nitrogen content in soils that already had relatively higher organic matter content. These results suggest that mulch application (with only soil surface disturbance) may not play a significant role in increasing soil carbon content and overall soil quality, at least in a short 4-year term.

Effect of sulfur content in a sulfur-activated carbon composite on the electrochemical properties of a lithium/sulfur battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Jin-Woo; Kim, Changhyeon; Ryu, Ho-Suk

2015-09-15

Highlights: • The content of sulfur in activated carbon was controlled by solution process. • The sulfur electrode with low sulfur content shows the best performance. • The Li/S battery has capacity of 1360 mAh/g at 1 C and 702 mAh/g at 10 C. - Abstract: The content of sulfur in sulfur/activated carbon composite is controlled from 32.37 wt.% to 55.33 wt.% by a one-step solution-based process. When the sulfur content is limited to 41.21 wt.%, it can be loaded into the pores of an activated carbon matrix in a highly dispersed state. On the contrary, when the sulfur contentmore » is 55.33 wt.%, crystalline sulfur can be detected on the surface of the activated carbon matrix. The best electrochemical performance can be obtained for a sulfur electrode with the lowest sulfur content. The sulfur/activated carbon composite with 32.37 wt.% sulfur afforded the highest first discharge capacity of 1360 mAh g{sup −1} at 1 C rate and a large reversible capacity of 702 mAh g{sup −1} at 10 C (16.75 A/g)« less

The influence of carbon content on cyclic fatigue of NiTi SMA wires.

PubMed

Matheus, T C U; Menezes, W M M; Rigo, O D; Kabayama, L K; Viana, C S C; Otubo, J

2011-06-01

To evaluate two NiTi wires with different carbon and oxygen contents in terms of mechanical resistance to rotary bending fatigue (RBF) under varied parameters of strain amplitude and rotational speed. The wires produced from two vacuum induction melting (VIM) processed NiTi ingots were tested, Ti-49.81 at%Ni and Ti-50.33 at%Ni, named VIM 1 and VIM 2. A brief analysis related to wire fabrication is also presented, as well as chemical and microstructural analysis by energy dispersive spectroscopy (EDS) and optical microscope, respectively. A computer controlled RBF machine was specially constructed for the tests. Three radii of curvature were used: 50.0, 62.5 and 75.0 mm, respectively, R(1), R(2) and R(3), resulting in three strain amplitudes ε(a) : 1.00%, 0.80% and 0.67%. The selected rotational speeds were 250 and 455 rpm. The VIM 1 wire had a high carbon content of 0.188 wt% and a low oxygen content of 0.036 wt%. The oxygen and carbon contents of wire VIM 2 did not exceed their maximum, of 0.070 and 0.050 wt%, according to ASTM standard (ASTM F-2063-00 2001). The wire with lower carbon content performed better when compared to the one with higher carbon content, withstanding 29,441 and 12,895 cycles, respectively, to fracture. The surface quality of the wire was associated with resistance to cyclic fatigue. Surface defects acted as stress concentrators points. Overall, the number of cycles to failure was higher for VIM 2 wires with lower carbon content. © 2011 International Endodontic Journal.

Seawater as the source of minor elements in black shales, phosphorites and other sedimentary rocks

USGS Publications Warehouse

Piper, D.Z.

1994-01-01

Many of the minor elements in seawater today have a concentration-depth profile similar to that of the biologically essential nutrients, NO-3 and PO3-4. They show a relative depletion in the photic zone and enrichment in the deep ocean. The difference between their surface- and deep-ocean values, normalized to the change in PO3-4, approaches the average of measured minor-element: P ratios in marine plankton, although individual analyses of the latter show extreme scatter for a variety of reasons. Despite this scatter in the minor-element analyses of plankton, agreement between the two sets of data shows unequivocally that an important marine flux of many minor elements through the ocean is in the form of biogenic matter, with a composition approaching that of plankton. This interpretation is further supported by sediment studies, particularly of sediments which accumulate in shelf-slope environments where biological productivity in the photic zone is exceptionally high and organic carbon contents of the underlying sediment elevated. The interelement relations observed for some of these sediments approach the average values of plankton. These same interelement relations are observed in many marine sedimentary rocks such as metalliferous black shales and phosphorites, rocks which have a high content of marine fractions (e.g., organic matter, apatite, biogenic silica and carbonates). Many previous studies of the geochemistry of these rocks have concluded that local hydrothermal activity, and/or seawater with an elemental content different from that of the modern ocean, was required to account for their minor-element contents. However, the similarity in several of the minor-element ratios in many of these formations to minor-element ratios in modern plankton demonstrates that these sedimentary rocks accumulated in environments whose marine chemistry was virtually identical to that seen on continental shelf-slopes, or in marginal seas, of the ocean today. The accumulation of the marine fraction of minor elements on these ancient sea floors was determined largely by the accumulation of organic matter, settling from the photic zone and with a composition of average plankton. A second marine fraction of minor elements in these rocks accumulated through precipitation and adsorption from seawater. The suite of elements in this fraction reflects redox conditions in the bottom water, as determined by bacterial respiration. For example, high Mn, high Cr+V and high Mo concentrations, above those which can be attributed to the accumulation of planktonic matter, characterize accumulation under bottom-water oxidizing, denitrifying and sulfate-reducing conditions, respectively. ?? 1994.

Optoelectronic system of online measurements of unburned carbon in coal fly ash

NASA Astrophysics Data System (ADS)

Golas, Janusz; Jankowski, Henryk; Niewczas, Bogdan; Piechna, Janusz; Skiba, Antoni; Szkutnik, Wojciech; Szkutnik, Zdzislaw P.; Wartak, Ryszarda; Worek, Cezary

2001-08-01

Carbon-in-ash level is an important consideration for combustion efficiency as well as ash marketing. The optoelectronic analyzing system for on-line determination and monitoring of the u burned carbon content of ash samples is presented. The apparatus operates on the principle that carbon content is proportional to the reflectance of IR light. Ash samples are collected iso kinetically from the flue gas duct and placed in a sample tube with a flat glass bottom. The same is then exposed to a light. The reflectance intensity is used by the system's computer to determine residual carbon content from correlation curves. The sample is then air purged back to the duct or to the attached sample canister to enable laboratory check analysis. The total cycle time takes between 5 and 10 minutes. Real time result of carbon content with accuracy 0.3-0.7 percent are reported and can be used for boiler controlling.

Carbon, nitrogen, and sulfur geochemistry of Archean and Proterozoic shales from the Kaapvaal Craton, South Africa

NASA Astrophysics Data System (ADS)

Watanabe, Yumiko; Naraoka, Hiroshi; Wronkiewicz, David J.; Condie, Kent C.; Ohmoto, Hiroshi

1997-08-01

The C, N, and S contents and VC and δ 13Cδ 34S values were analyzed for 100 shale samples from ten formations, 3.0 to 2.1 Ga in age, in the central and eastern regions of the Kaapvaal Craton, South Africa. The Kaapvaal shales are characterized by generally low contents of organic C (range 0.06-2.79 wt%, average 0.47 wt%), N (range <0.01-0.09 wt%, average 0.1 wt%), and S (range <0.01-1.63 wt%, average 0.1 wt%). The low N/C (<0.005) and H/C (mostly ˜0.2) atomic ratios in kerogens from the shales indicated that the Kaapvaal shales lost considerable amounts of N, C, S, and H during diagenesis and regional metamorphism (up to the greenschist facies). From the theoretical relationships between the H/C ratios of kerogen and organic C contents of shales, the original C contents of the Archean and Proterozoic shales from the Kaapvaal Craton are estimated to be on average ˜2 wt%. These values are similar to the average organic C content of modern marine sediments. This suggests that the primary organic productivity and the preservation of organic matter in the ocean during the period of 3.0 to 2.1 Ga were similar to those in the Phanerozoic era, provided the flux of clastic sediments to the ocean was similar. This would also imply that the rate of O 2 accumulation in the atmosphere-ocean system, which has equaled the burial rate of organic matter in sediments, has been the same since ˜3.0 Ga. The δ 34S values of bulk-rock sulfides (mostly pyrite) range from +2.7 to +7.4%‰ for seven sulfide-rich samples of ˜2.9 Ga to ˜2.6 Ga. These values are consistent with a suggestion by Ohmoto (1992) and Ohmoto et al. (1993) that most pyrite crystals in Archean shales were formed by bacterial reduction of seawater sulfate with δ 34S values between +2 and +10‰, and that the Archean seawater was sulfate rich. Changes in the δ 13C org values during maturation of kerogen were evaluated with theoretical calculations from the experimental data of Peters et al. (1981) and Lewan (1983), and from the observations by Simoneit et al. (1981) on natural samples. These evaluations suggest that the magnitudes of δ 13C org increase are much less than those estimated by Hayes et al. (1983) and Des Marais et al. (1992), and only about 2 to 3%‰ for the kerogens that decreased their H/C ratios from 1.5 to less than 0.3. Based on the relationships among sulfide-S contents, organic-C contents, and δ 13C org values, four different types of depositional environments are identified for the Archean and early Proterozoic shales in the Kaapvaal Craton: (I) euxinic marine basins, characterized by normal marine organisms with δ 13C org= -33 ± 3%‰ (II) near-shore, oxic marine environment, characterized by normal marine organisms with δ 13C org = -31 ± 3%‰; (III) hypersaline, low-sulfate lakes, characterized by organisms with δ 13C org= -2 ± 3%‰; and (IV) euxinic, marine basins which supported the activity of methanogenic and methanotrophic bacteria and accumulated organic matter with δ 13C org= -43 ± 3%‰. In contrast to the currently popular model positing a global anoxic ocean prior to ˜2.2 Ga (e.g., Des Marais et al, 1992; Hayes, 1994; Logan et al., 1995), this study suggests that the development of anoxic basins, which accumulated Group II and IV sediments, occurred only regionally and episodically during the period between 3.0 Ga and 2.1 Ga. This further suggests that the normal ocean has been oxic since at least ˜3.0 Ga. Diversifications of environments, as well as of biological species, had already occurred ˜3.0 Ga. The carbon isotope mass balance calculation suggests that the removal rates of organic C and carbonate C from the ocean and the weathering rates of organic C and carbonate C on the continents during the 3.0-2.1 Ga period were basically the same as those in the Phanerozoic era. This would have been possible only if the atmospheric P O 2 level had been basically constant since at least 3.0 Ga. The results of this study, therefore, add to a growing list of evidence that the atmosphere has been oxic (i.e., P O 2 > 1%PAL) since at least 3.0 Ga. The list of evidence includes the sulfur isotope data on Archean sedimentary rocks ( Ohmoto and Felder, 1987; Ohmoto et al., 1993), the Fe 3+Ti ratios of paleosols ( Ohmoto, 1996), and the paragenesis of minerals in the "detrital" gold-uranium ores in pre-2.0 Ga quartz pebble beds that suggests nondetrital origins for uraninite and pyrite in these deposits ( Barnicoat et al., 1997).

Molecular distributions of water soluble dicarboxylic acids in marine aerosols over the Pacific Ocean including tropics

NASA Astrophysics Data System (ADS)

Kawamura, Kimitaka; Sakaguchi, Futoshi

1999-02-01

Remote marine aerosols collected over the western North to equatorial Pacific (34°N-14°S, 140°E-150°W) were studied for low molecular weight dicarboxylic acids using a capillary gas chromatography (GC) and GC/mass spectrometer, and for total carbon and nitrogen contents. Homologous series of dicarboxylic acids (C2-C10) including keto- and hydroxy-dicarboxylic acids were detected in the samples with a concentration range of 10-250 ng m-3 (average 63 ng m-3 and median 44 ng m-3). Their molecular distributions showed a predominance of oxalic acid (C2), followed by malonic acid (C3). The smallest diacid (C2, 6.5-161 ng m-3 with average 40 ng m-3 and median 17 ng m-3) composed 45-75% (average 65%) of the total diacids. The diacids showed higher concentrations in the western Pacific rim near Japanese islands and showed lower concentrations in the central and tropical Pacific. However, relative abundances of the diacid-carbon in the total aerosol carbon (1.1-15.8%) were found to be higher in the equatorial central Pacific. These diacids are probably in situ produced in the Pacific atmosphere by photochemical oxidation of gaseous and particulate precursors. Results of principal component analysis of individual diacid, coupled with an information on photochemical reactions, further support that C2 and C3 diacids are likely produced by the oxidation of C4 and longer-chain diacids, whereas longer-chain (C5-C10) diacids are produced through the oxidation of semivolatile fatty acids which are also oxidation products of unsaturated fatty acids. Concentrations of total C (0.069-5.27 μg m-3 with average 0.39 μg m-3 and median 0.15 μg m-3) and total N (0.026-1.44 μg m-3 with average 0.12 μg m-3 and median 0.077 μg m-3) were generally higher over the western Pacific.

The impact of enhanced atmospheric carbon dioxide on yield, proximate composition, elemental concentration, fatty acid and vitamin C contents of tomato (Lycopersicon esculentum).

PubMed

Khan, Ikhtiar; Azam, Andaleeb; Mahmood, Abid

2013-01-01

The global average temperature has witnessed a steady increase during the second half of the twentieth century and the trend is continuing. Carbon dioxide, a major green house gas is piling up in the atmosphere and besides causing global warming, is expected to alter the physico-chemical composition of plants. The objective of this work was to evaluate the hypothesis that increased CO(2) in the air is causing undesirable changes in the nutritional composition of tomato fruits. Two varieties of tomato (Lycopersicon esculentum) were grown in ambient (400 μmol mol(-1)) and elevated (1,000 μmol mol(-1)) concentration of CO(2) under controlled conditions. The fruits were harvested at premature and fully matured stages and analyzed for yield, proximate composition, elemental concentration, fatty acid, and vitamin C contents. The amount of carbohydrates increased significantly under the enhanced CO(2) conditions. The amount of crude protein and vitamin C, two important nutritional parameters, decreased substantially. Fatty acid content showed a mild decrease with a slight increase in crude fiber. Understandably, the effect of enhanced atmospheric CO(2) was more pronounced at the fully matured stage. Mineral contents of the fruit samples changed in an irregular fashion. Tomato fruit has been traditionally a source of vitamin C, under the experimental conditions, a negative impact of enhanced CO(2) on this source of vitamin C was observed. The nutritional quality of both varieties of tomato has altered under the CO(2) enriched atmosphere.

Characteristics of maize biochar with different pyrolysis temperatures and its effects on organic carbon, nitrogen and enzymatic activities after addition to fluvo-aquic soil.

PubMed

Wang, Xiubin; Zhou, Wei; Liang, Guoqing; Song, Dali; Zhang, Xiaoya

2015-12-15

In this study, the characteristics of maize biochar produced at different pyrolysis temperatures (300, 450 and 600°C) and its effects on organic carbon, nitrogen and enzymatic activities after addition to fluvo-aquic soil were investigated. As pyrolysis temperature increased, ash content, pH, electrical conductivity, surface area, pore volume and aromatic carbon content of biochar increased while yield, ratios of oxygen:carbon and hydrogen: carbon and alkyl carbon content decreased. During incubation, SOC, total N, and ammonium-N contents increased in all biochar-amended treatments compared with the urea treatment; however, soil nitrate-N content first increased and then decreased with increasing pyrolysis temperature of the applied biochar. Extracellular enzyme activities associated with carbon transformation first increased and then decreased with biochars pyrolyzed at 450 and 600°C. Protease activity markedly increased with increased pyrolysis temperatures, whereas pyrolysis temperature had limited effect on soil urease activity. The results indicated that the responses of extracellular enzymes to biochar were dependent on the pyrolysis temperature, the enzyme itself and incubation time as well. Copyright © 2015. Published by Elsevier B.V.

Local Environmental Factors Drive Divergent Grassland Soil Bacterial Communities in the Western Swiss Alps

PubMed Central

Pinto-Figueroa, Eric; Buri, Aline; Spangenberg, Jorge E.; Adatte, Thierry; Guisan, Antoine; van der Meer, Jan Roelof

2016-01-01

ABSTRACT Mountain ecosystems are characterized by a diverse range of climatic and topographic conditions over short distances and are known to shelter a high biodiversity. Despite important progress, still little is known on bacterial diversity in mountain areas. Here, we investigated soil bacterial biogeography at more than 100 sampling sites randomly stratified across a 700-km2 area with 2,200-m elevation gradient in the western Swiss Alps. Bacterial grassland communities were highly diverse, with 12,741 total operational taxonomic units (OTUs) across 100 sites and an average of 2,918 OTUs per site. Bacterial community structure was correlated with local climatic, topographic, and soil physicochemical parameters with high statistical significance. We found pH (correlated with % CaO and % mineral carbon), hydrogen index (correlated with bulk gravimetric water content), and annual average number of frost days during the growing season to be among the groups of the most important environmental drivers of bacterial community structure. In contrast, bacterial community structure was only weakly stratified as a function of elevation. Contrasting patterns were discovered for individual bacterial taxa. Acidobacteria responded both positively and negatively to pH extremes. Various families within the Bacteroidetes responded to available phosphorus levels. Different verrucomicrobial groups responded to electrical conductivity, total organic carbon, water content, and mineral carbon contents. Alpine grassland bacterial communities are thus highly diverse, which is likely due to the large variety of different environmental conditions. These results shed new light on the biodiversity of mountain ecosystems, which were already identified as potentially fragile to anthropogenic influences and climate change. IMPORTANCE This article addresses the question of how microbial communities in alpine regions are dependent on local climatic and soil physicochemical variables. We benefit from a unique 700-km2 study region in the western Swiss Alps region, which has been exhaustively studied for macro-organismal and fungal ecology, and for topoclimatic modeling of future ecological trends, but without taking into account soil bacterial diversity. Here, we present an in-depth biogeographical characterization of the bacterial community diversity in this alpine region across 100 randomly stratified sites, using 56 environmental variables. Our exhaustive sampling ensured the detection of ecological trends with high statistical robustness. Our data both confirm previously observed general trends and show many new detailed trends for a wide range of bacterial taxonomic groups and environmental parameters. PMID:27542929

Acid neutralizing capacity and leachate results for igneous rocks, with associated carbon contents of derived soils, Animas River AML site, Silverton, Colorado

USGS Publications Warehouse

Yager, Douglas B.; Stanton, Mark R.; Choate, LaDonna M.; Burchell,

2009-01-01

Mine planning efforts have historically overlooked the possible acid neutralizing capacity (ANC) that local igneous rocks can provide to help neutralize acidmine drainage. As a result, limestone has been traditionally hauled to mine sites for use in neutralizing acid drainage. Local igneous rocks, when used as part of mine life-cycle planning and acid mitigation strategy, may reduce the need to transport limestone to mine sites because these rocks can contain acid neutralizing minerals. Igneous hydrothermal events often introduce moderately altered mineral assemblages peripheral to more intensely altered rocks that host metal-bearing veins and ore bodies. These less altered rocks can contain ANC minerals (calcite-chlorite-epidote) and are referred to as a propylitic assemblage. In addition, the carbon contents of soils in areas of new mining or those areas undergoing restoration have been historically unknown. Soil organic carbon is an important constituent to characterize as a soil recovery benchmark that can be referred to during mine cycle planning and restoration.
This study addresses the mineralogy, ANC, and leachate chemistry of propylitic volcanic rocks that host polymetallic mineralization in the Animas River watershed near the historical Silverton, Colorado, mining area. Acid titration tests on volcanic rocks containing calcite (2 – 20 wt %) and chlorite (6 – 25 wt %), have ANC ranging from 4 – 146 kg/ton CaCO₃ equivalence. Results from a 6-month duration, kinetic reaction vessel test containing layered pyritic mine waste and underlying ANC volcanic rock (saturated with deionized water) indicate that acid generating mine waste (pH 2.4) has not overwhelmed the ANC of propylitic volcanic rocks (pH 5.8). Sequential leachate laboratory experiments evaluated the concentration of metals liberated during leaching. Leachate concentrations of Cu-Zn-As-Pb for ANC volcanic rock are one-to-three orders of magnitude lower when compared to leached solution from mine waste used in the kinetic reaction vessel test. This finding suggests that mine waste and not ANC rock may generate the majority of leachable metals in a field scenario.
The organic carbon content of naturally reclaimed soils derived from weathering of propylitically-altered andesite was determined in catchments where ANC studies were initiated. Soils were found to have total carbon concentrations (TOC) that exceed global average soil TOC abundances by as much as 1.5 – 5 times. These data support an environmental management system involving use of ANC rocks as part of life-cycle mine planning to reduce post-mine closure acid mitigation measures. Carbon contents of undisturbed soils in mined catchments can possibly be used to validate post-reclamation success and help quantify carbon sequestration for CO₂ emission offset trading as carbon markets mature.

A study of ignition of metal impregnated carbons: the influence of oxygen content in the activated carbon matrix.

PubMed

van der Merwe, M M; Bandosz, T J

2005-02-01

A study of the reason for the early ignition of coconut-based impregnated carbon in comparison with the peat-based impregnated carbon was conducted. The surface features of carbons were evaluated using various physicochemical methods. The metal analysis of the initial carbon indicated that the content of potassium was higher in the coconut-based carbon. The surface functional group analysis revealed the presence of similar surface species; however, the peat-based carbon was more acidic in its chemical nature. Since the oxygen content was higher in the peat-based carbon, the early ignition of the coconut-based material was attributed to its higher affinity to chemisorb oxygen, which leads to exothermic effects. This conclusion was confirmed by performing oxidation of coconut-based carbon prior to impregnation. This process increased the ignition temperature for Cu/Cr impregnated coconut-based material from 186 to 289 degrees C and for the Cu/Zn/Mo impregnated carbon from 235 to 324 degrees C.

Efficiency of transfer of essential polyunsaturated fatty acids versus organic carbon from producers to consumers in a eutrophic reservoir.

PubMed

Gladyshev, Michail I; Sushchik, Nadezhda N; Anishchenko, Olesia V; Makhutova, Olesia N; Kolmakov, Vladimir I; Kalachova, Galina S; Kolmakova, Anzhelika A; Dubovskaya, Olga P

2011-02-01

One of the central paradigms of ecology is that only about 10% of organic carbon production of one trophic level is incorporated into new biomass of organisms of the next trophic level. Many of energy-yielding compounds of carbon are designated as 'essential', because they cannot be synthesized de novo by consumers and must be obtained with food, while they play important structural and regulatory functions. The question arises: are the essential compounds transferred through trophic chains with the same efficiency as bulk carbon? To answer this question, we measured gross primary production of phytoplankton and secondary production of zooplankton and content of organic carbon and essential polyunsaturated fatty acids of ω-3 family with 18-22 carbon atoms (PUFA) in the biomass of phytoplankton and zooplankton in a small eutrophic reservoir during two summers. Transfer efficiency between the two trophic levels, phytoplankton (producers) and zooplankton (consumers), was calculated as ratio of the primary production versus the secondary (zooplankton) production for both carbon and PUFA. We found that the essential PUFA were transferred from the producers to the primary consumers with about twice higher efficiency than bulk carbon. In contrast, polyunsaturated fatty acids with 16 carbon atoms, which are synthesized exclusively by phytoplankton, but are not essential for animals, had significantly lower transfer efficiency than both bulk carbon, and essential PUFA. Thus, the trophic pyramid concept, which implicitly implies that all the energy-yielding compounds of carbon are transferred from one trophic level to the next with the same efficiency of about on average 10%, should be specified for different carbon compounds.

Preparation and mechanical properties of photo-crosslinked poly(trimethylene carbonate) and nano-hydroxyapatite composites.

PubMed

Geven, Mike A; Barbieri, Davide; Yuan, Huipin; de Bruijn, Joost D; Grijpma, Dirk W

2015-01-01

Composite materials of photo-crosslinked poly(trimethylene carbonate) and nanoscale hydroxyapatite were prepared and their mechanical characteristics for application as orbital floor implants were assessed. The composites were prepared by solvent casting poly(trimethylene carbonate) macromers with varying amounts of nano-hydroxyapatite and subsequent photo-crosslinking. The incorporation of the nano-hydroxyapatite into the composites was examined by thermogravimetric analysis, scanning electron microscopy and gel content measurements. The mechanical properties were investigated by tensile testing and trouser tearing experiments. Our results show that nano-hydroxyapatite particles can readily be incorporated into photo-crosslinked poly(trimethylene carbonate) networks. Compared to the networks without nano-hydroxyapatite, incorporation of 36.3 wt.% of the apatite resulted in an increase of the E modulus, yield strength and tensile strength from 2.2 MPa to 51 MPa, 0.5 to 1.4 N/mm2 and from 1.3 to 3.9 N/mm2, respectively. We found that composites containing 12.4 wt.% nano-hydroxyapatite had the highest values of strain at break, toughness and average tear propagation strength (376% , 777 N/mm2 and 3.1 N/mm2, respectively).

Semi-Quantitative Evaluation of Secondary Carbonates via Portable X-ray Fluorescence Spectrometry

NASA Astrophysics Data System (ADS)

Chakraborty, Somsubhra; Weindorf, David; Weindorf, Camille; Duda, Bogdan; Pennington, Sarah; Ortiz, Rebekah

2017-04-01

Secondary calcium carbonate commonly occurs in subsoils of semi-arid soils worldwide. In US Soil Taxonomy, such horizons are frequently described as Bk, Bkk, Bkm, Bkkm, or Ck horizons at variable stages of development. Specifically, the Soil Survey Staff uses a qualitative scale of one through six to indicate differential developmental stages. However, considerable disagreement exists even among experienced soil scientists. Evaluating 75 soil samples from across four US states, a portable X-ray fluorescence (PXRF) spectrometer was used to quantify the total soil Ca content and compare it to average developmental stage scores as determined by a panel of Soil Survey Staff personnel. Samples were evaluated both as intact aggregates as well as ground (<2 mm), homogenized powders. PXRF readings of total soil Ca concentration steadily increased under both conditions as developmental stage progressed. However, minimal difference was observed between stage five and six carbonate accumulation. Stage three showed the widest variability in total soil Ca. Given than PXRF cannot distinguish between primary and secondary CaCO3 in soils, interpretation by the analyst remains essential. Nonetheless, PXRF provides an important tool for assessing carbonate laden subsoils providing elemental differentiation beyond that perceived by the human eye.

Effect of Graphitic Content on Carbon Supported Catalyst Performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, Anant; Artyushkova, Kateryna; Atanassov, Plamen

2011-07-01

The effect of graphitic content on carbon supported platinum catalysts was investigated in order to investigate its influence on catalyst performance. Four catalysts of varying surface areas and graphitic content were analyzed using XPS, HREELS, and tested using RDE experiments. The catalysts were also heat treated at 150oC and 100%RH as means to uniformly age them. The heat treated samples were analyzed using the same methods to determine what changes had occurred due to this aging process. When compared to the BOL catalysts, heat treated catalysts displayed increased graphitic carbon and platinum metalic content, however they also showed depressed catalyticmore » activity. The primary cause is still under investigation, though it is believed to be related to loss of amorphous carbon content.« less

The Vegetation Nitrogen Content and its Latitudinal Patterns in China

NASA Astrophysics Data System (ADS)

Zhao, Hang; He, Nianpeng; Yu, Guirui; Wang, Qiufeng

2017-04-01

Nitrogen is an essential nutrient element in biological life activities, and plays an important role in plant production and growth. Vegetation nitrogen content can be used as an important component in estimating ecosystem nitrogen storage. In the present study, we used a large amount of data from the database of north-south transects of eastern China and published literatures. We explored the nitrogen content of different components of China terrestrial ecosystems and its latitude pattern at the scales of the plots and of 8 eco-regions. The average nitrogen content of the forest ecosystem was 1.797% in the tree leaves, 0.663% in the tree branch, 0.586% in the tree stem, 0.755% in the tree root. In the shrub layer, the average leaf nitrogen content is 1.845%, the average branch content is 0.968% and the average root nitrogen content is 0.995%. In the herb layer, the average nitrogen content of aboveground is 2.463% and 1.279% for underground. The average nitrogen content of aboveground in grassland ecosystem is 2.006% and 0.994% for underground. The average aboveground nitrogen content in desert ecosystem is 1.911%. The average nitrogen contents of the leaves, stems and roots in wetland ecosystem were 1.669%, 0.741% and 0.659%. There were significant differences in nitrogen content among different organs, and it showed that the nitrogen content of leaves > roots > branches > trunks and aboveground component > underground component. The nitrogen content of different components in China terrestrial ecosystems increased with increasing latitude, especially in leaf. These results demonstrated latitudinal patterns of nitrogen content in Chinese terrestrial ecosystems, based on field-measured data, and provided a reference or standard for regional vegetation nitrogen allocation and storage estimations.

In-Situ Crafting of ZnFe₂O₄ Nanoparticles Impregnated within Continuous Carbon Network as Advanced Anode Materials.

PubMed

Jiang, Beibei; Han, Cuiping; Li, Bo; He, Yanjie; Lin, Zhiqun

2016-02-23

The ability to create a synergistic effect of nanostructure engineering and its hybridization with conductive carbonaceous material is highly desirable for attaining high-performance lithium ion batteries (LIBs). Herein, we judiciously crafted ZnFe2O4/carbon nanocomposites composed of ZnFe2O4 nanoparticles with an average size of 16 ± 5 nm encapsulated within the continuous carbon network as anode materials for LIBs. Such intriguing nanocomposites were yielded in situ via the pyrolysis-induced carbonization of polystyrene@poly(acrylic acid) (PS@PAA) core@shell nanospheres in conjunction with the formation of ZnFe2O4 nanoparticles through the thermal decomposition of ZnFe2O4 precursors incorporated within the PS@PAA nanospheres. By systematically varying the ZnFe2O4 content in the ZnFe2O4/carbon nanocomposites, the nanocomposite containing 79.3 wt % ZnFe2O4 was found to exhibit an excellent rate performance with high capacities of 1238, 1198, 1136, 1052, 926, and 521 mAh g(-1) at specific currents of 100, 200, 500, 1000, 2000, and 5000 mA g(-1), respectively. Moreover, cycling performance of the ZnFe2O4/carbon nanocomposite with 79.3 wt % ZnFe2O4 at specific currents of 200 mA g(-1) delivered an outstanding prolonged cycling stability for several hundred cycles.

Sources and formation mechanisms of carbonaceous aerosol at a regional background site in the Netherlands: insights from a year-long radiocarbon study

NASA Astrophysics Data System (ADS)

Dusek, Ulrike; Hitzenberger, Regina; Kasper-Giebl, Anne; Kistler, Magdalena; Meijer, Harro A. J.; Szidat, Sönke; Wacker, Lukas; Holzinger, Rupert; Röckmann, Thomas

2017-03-01

We measured the radioactive carbon isotope 14C (radiocarbon) in various fractions of the carbonaceous aerosol sampled between February 2011 and March 2012 at the Cesar Observatory in the Netherlands. Based on the radiocarbon content in total carbon (TC), organic carbon (OC), water-insoluble organic carbon (WIOC), and elemental carbon (EC), we estimated the contribution of major sources to the carbonaceous aerosol. The main source categories were fossil fuel combustion, biomass burning, and other contemporary carbon, which is mainly biogenic secondary organic aerosol material (SOA). A clear seasonal variation is seen in EC from biomass burning (ECbb), with lowest values in summer and highest values in winter, but ECbb is a minor fraction of EC in all seasons. WIOC from contemporary sources is highly correlated with ECbb, indicating that biomass burning is a dominant source of contemporary WIOC. This suggests that most biogenic SOA is water soluble and that water-insoluble carbon stems mainly from primary sources. Seasonal variations in other carbon fractions are less clear and hardly distinguishable from variations related to air mass history. Air masses originating from the ocean sector presumably contain little carbonaceous aerosol from outside the Netherlands, and during these conditions measured carbon concentrations reflect regional sources. In these situations absolute TC concentrations are usually rather low, around 1.5 µg m-3, and ECbb is always very low ( ˜ 0.05 µg m-3), even in winter, indicating that biomass burning is not a strong source of carbonaceous aerosol in the Netherlands. In continental air masses, which usually arrive from the east or south and have spent several days over land, TC concentrations are on average by a factor of 3.5 higher. ECbb increases more strongly than TC to 0.2 µg m-3. Fossil EC and fossil WIOC, which are indicative of primary emissions, show a more moderate increase by a factor of 2.5 on average. An interesting case is fossil water-soluble organic carbon (WSOC, calculated as OC-WIOC), which can be regarded as a proxy for SOA from fossil precursors. Fossil WSOC has low concentrations when regional sources are sampled and increases by more than a factor of 5 in continental air masses. A longer residence time of air masses over land seems to result in increased SOA concentrations from fossil origin.

Ocean carbon and heat variability in an Earth System Model

NASA Astrophysics Data System (ADS)

Thomas, J. L.; Waugh, D.; Gnanadesikan, A.

2016-12-01

Ocean carbon and heat content are very important for regulating global climate. Furthermore, due to lack of observations and dependence on parameterizations, there has been little consensus in the modeling community on the magnitude of realistic ocean carbon and heat content variability, particularly in the Southern Ocean. We assess the differences between global oceanic heat and carbon content variability in GFDL ESM2Mc using a 500-year, pre-industrial control simulation. The global carbon and heat content are directly out of phase with each other; however, in the Southern Ocean the heat and carbon content are in phase. The global heat mutli-decadal variability is primarily explained by variability in the tropics and mid-latitudes, while the variability in global carbon content is primarily explained by Southern Ocean variability. In order to test the robustness of this relationship, we use three additional pre-industrial control simulations using different mesoscale mixing parameterizations. Three pre-industrial control simulations are conducted with the along-isopycnal diffusion coefficient (Aredi) set to constant values of 400, 800 (control) and 2400 m2 s-1. These values for Aredi are within the range of parameter settings commonly used in modeling groups. Finally, one pre-industrial control simulation is conducted where the minimum in the Gent-McWilliams parameterization closure scheme (AGM) increased to 600 m2 s-1. We find that the different simulations have very different multi-decadal variability, especially in the Weddell Sea where the characteristics of deep convection are drastically changed. While the temporal frequency and amplitude global heat and carbon content changes significantly, the overall spatial pattern of variability remains unchanged between the simulations.

Geohydrologic reconnaissance of the upper Potomac River basin

USGS Publications Warehouse

Trainer, Frank W.; Watkins, Frank A.

1975-01-01

The upper Potomac River basin, in the central Appalachian region in Pennsylvania, Maryland, Virginia, and West Virginia, is a humid temperate region of diverse fractured rocks. Three geohydrologic terranes, which underlie large parts of the basin, are described in terms of their aquifer characteristics and of the magnitude and duration of their base runoff: (1) fractured rock having a thin regolith, (2) fractured rock having a thick regolith, and (3) carbonate rock. Crystalline rock in the mountainous part of the Blue Ridge province and shale with tight sandstone in the folded Appalachians are covered with thin regolith. Water is stored in and moves through fairly unmodified fractures. Average transmissivity (T) is estimated to be 150 feet squared per day, and average storage coefficient (S), 0.005. Base runoff declines rapidly from its high levels during spring and is poorly sustained during the summer season of high evapotranspiration. The rocks in this geohydrologic terrane are the least effective in the basin for the development of water supplies and as a source of dry-weather streamflow. Crystalline and sedimentary rocks in the Piedmont province and in the lowland part of the Blue Ridge province are covered with thick regolith. Water is stored in and moves through both the regolith and the underlying fractured rock. Estimated average values for aquifer characteristics are T, 200 feet squared per day, and S, 0.01. Base runoff is better sustained in this terrane than in the thin-regolith terrane and on the average .is about twice as great. Carbonate rock, in which fractures have been widened selectively by solution, especially near streams, has estimated average aquifer characteristics of T, 500 feet squared per day, and S, 0.03-0.04. This rock is the most effective in the basin in terms of water supply and base runoff. Where its fractures have not been widened by solution, the carbonate rock is a fractured-rock aquifer much like the noncarbonate rock. At low values the frequency of specific capacities of wells is much the same in all rocks in the basin, but high values of specific capacity are as much as 10 times more frequent in carbonate rock than in noncarbonate rock. Nearly all the large springs and high-capacity wells in the basin are in carbonate rock. Base runoff from the carbonate rock is better sustained during dry weather and on the average is about three times as great as base runoff from fractured rock having a thin regolith. The potential role of these water-bearing terranes in water management probably lies in the local development of large water supplies from the carbonate rock and in the possible manipulation of underground storage for such purposes as providing space for artificial recharge of ground water and providing ground water to be used for the augmentation of low streamflow. The chief water-quality problems in the basin--acidic mine-drainage water in the western part of the basin, local highly mineralized ground water, and the high nitrate content of ground water in some of the densely populated parts of the basin--would probably have little adverse affect on the use of ground water for low-flow augmentation.

Munsell color value as related to organic carbon in Devonian shale of Appalachian basin

USGS Publications Warehouse

Hosterman, J.W.; Whitlow, S.I.

1981-01-01

Comparison of Munsell color value with organic carbon content of 880 samples from 50 drill holes in Appalachian basin shows that a power curve is the best fit for the data. A color value below 3 to 3.5 indicates the presence of organic carbon but is meaningless in determining the organic carbon content because a large increase in amount of organic carbon causes only a minor decrease in color value. Above 4, the color value is one of the factors that can be used in calculating the organic content. For samples containing equal amounts of organic carbon, calcareous shale containing more than 5% calcite is darker than shale containing less than 5% calcite.-Authors

Denaturing gradient gel electrophoresis fingerprinting of soil bacteria in the vicinity of the Chinese Great Wall Station, King George Island, Antarctica.

PubMed

Pan, Qi; Wang, Feng; Zhang, Yang; Cai, Minghong; He, Jianfeng; Yang, Haizhen

2013-08-01

Bacterial diversity was investigated in soil samples collected from 13 sites around the Great Wall Station, Fildes Peninsula, King George Island, Antarctica, using denaturing gradient gel electrophoresis (DGGE) of 16S rRNA genes. The classes alpha-, beta-, and gamma-Proteobacteria, as well as the phylum Actinobacteria, were found to be the dominant bacteria in the soils around the Great Wall Station. Although the selected samples were not contaminated by oil, a relationship between soil parameters, microbial biodiversity, and human impact was still seen. Sample sites in human impacted areas showed lower bacterial biodiversity (average H' = 2.65) when compared to non-impacted sites (average H' = 3.05). There was no statistically significant correlation between soil bacterial diversity and total organic carbon (TOC), total nitrogen, or total phosphorus contents of the soil. Canonical correlation analysis showed that TOC content was the most important factor determining bacterial community profiles among the measured soil parameters. In conclusion, microbial biodiversity and community characteristics within relatively small scales (1.5 km) were determined as a function of local environment parameters and anthropogenic impact.

Exploring the multiplicity of soil-human interactions: organic carbon content, agro-forest landscapes and the Italian local communities.

PubMed

Salvati, Luca; Barone, Pier Matteo; Ferrara, Carlotta

2015-05-01

Topsoil organic carbon (TOC) and soil organic carbon (SOC) are fundamental in the carbon cycle influencing soil functions and attributes. Many factors have effects on soil carbon content such as climate, parent material, land topography and the human action including agriculture, which sometimes caused a severe loss in soil carbon content. This has resulted in a significant differentiation in TOC or SOC at the continental scale due to the different territorial and socioeconomic conditions. The present study proposes an exploratory data analysis assessing the relationship between the spatial distribution of soil organic carbon and selected socioeconomic attributes at the local scale in Italy with the aim to provide differentiated responses for a more sustainable use of land. A strengths, weaknesses, opportunities and threats (SWOT) analysis contributed to understand the effectiveness of local communities responses for an adequate comprehension of the role of soil as carbon sink.

Chernozems microbial community under anthropogenic impact (Russia)

NASA Astrophysics Data System (ADS)

Ivashchenko, Kristina; Ananyeva, Nadezhda; Sushko, Sofia; Vasenev, Viacheslav

2017-04-01

Chernozems is important natural resource, which in the last decade under intense influence as a result of plowing and urbanization. The parameters of soil microbial community functioning might be identify some soil deterioration under the impacts. Our research was focused on assessment of microbial community status in different soil layers of virgin steppe, bare fallow and urban ecosystems (Kursk region). In each ecosystem, we chose randomly 3-5 spatially distributed sites, where soil samples were collected by auguring up to 0.5 m depth (each layer 10 cm thickness) and up to 1.5 m depth (0-10, 10-50, 50-100, 100-150 cm layers), totally 127 samples. The bulk density was measured for these soil layers. In all soil samples the microbial biomass carbon content (Cmic) was analyzed by substrate-induced respiration (SIR) method and basal respiration (BR) was assessed by CO2 rate production. The fungi-to-bacteria ratio (selective inhibition technique with antibiotics) was determined and portion of Cmic in soil organic carbon (Corg) content was calculated in topsoil (0-10 cm). The Corg (dichromate oxidation) and pHw (potentiometry) values were measured. The Cmic and BR profile pools were calculated using bulk density and thickness of studied layers. The Cmic (0-10 cm) was varied from 84 to 1954 µg C g-1 soil, in steppe it was on average 3-4 times higher than those in bare fallow and urban. The BR rate was amounted from 0.20 to 1.57 µg CO2-C g-1 soil h-1, however no significant difference between studied ecosystems was found. It was shown the relationship between Cmic, BR and Corg (the linear regression, R2=0.92 and 0.75, respectively, p<0.05). The Cmic / Corg ratio in steppe was on average 3.3%, it was significantly higher those bare fallow and urban (1.6 and 0.7%, respectively). The fungi-to-bacteria ratio was decreased along ecosystems row: virgin steppe>bare fallow>urban, and it was on average 6.0, 5.2 and 1.8, respectively. The Cmic profile pool (0.5 m) of steppe was reached up on average 206 g C m-2, and it was 2.0 and 2.5 times higher those bare fallow and urban, respectively. The BR profile pool (0.5 m) in steppe and bare fallow was reached up 5.9 and 5.8 g CO2-C m-2 d-1, respectively, it was on average 2 times higher urban. The Cmic profile pool (1.5 m) in steppe was amounted to 372 g C m-2, and it was essentially higher those in bare fallow and urban (138 and 140 g C m-2, respectively). The BR profile pool (1.5 m) was also decreased along ecosystems row: steppe> fallow>urban, and it was on average 13.0, 8.0 and 5.6 g CO2-C m-2 d-1, respectively. Thus, we found a significant decreasing soil microbial biomass content, its portion in soil Corg, fungi content, and the Cmic and BR profile pools along Chernozems' ecosystems gradient from natural (virgin steppe) to anthropogenically transformed (bare fallow, urban). It might be illustrated some deterioration of soil microbial community functioning under plowing and urbanization. This research was supported by RFBR grants Nos. 15-04-00915 and 16-34-00398

Spectroscopic characterization of furosemide binding to human carbonic anhydrase II.

PubMed

Ranjbar, Samira; Ghobadi, Sirous; Khodarahmi, Reza; Nemati, Houshang

2012-05-01

This study reports the interaction between furosemide and human carbonic anhydrase II (hCA II) using fluorescence, UV-vis and circular dichroism (CD) spectroscopy. Fluorescence data indicated that furosemide quenches the intrinsic fluorescence of the enzyme via a static mechanism and hydrogen bonding and van der Walls interactions play the major role in the drug binding. The binding average distance between furosemide and hCA II was estimated on the basis of the theory of Förster energy transfer. Decrease of protein surface hydrophobicity was also documented upon furosemide binding. Chemical modification of hCA II using N-bromosuccinimide indicated decrease of the number of accessible tryptophans in the presence of furosemide. CD results suggested the occurance of some alterations in α-helical content as well as tertiary structure of hCA II upon drug binding. Copyright © 2012 Elsevier B.V. All rights reserved.

Hydrothermal carbon nanosphere-based agglomerated anion exchanger for ion chromatography.

PubMed

Zhao, Qiming; Wu, Shuchao; Zhang, Kai; Lou, Chaoyan; Zhang, Peiming; Zhu, Yan

2016-10-14

This work reports the application of hydrothermal carbon nanospheres (HCNSs) as stationary phases in ion chromatography. HCNSs were facilely quaternized through polycondensation of methylamine and 1,4-butanediol diglycidyl ether. The quaternization was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Owing to the electrostatic interaction, quaternized HCNSs were equably attached onto the surface of sulfonated polystyrene-divinylbenzene (PS-DVB) beads to construct the anion exchangers. The aggregation was verified by scanning electron microscopy and elemental analysis. Common anions, aliphatic monocarboxylic acids, polarizable anions, and aromatic acids were well separated on the stationary phases with good stability and symmetry. The prepared column was further applied to detect phosphate content in Cola drink samples. The limit of detection (S/N=3) was 0.09mg/L, and the relative standard deviation (n=10) of retention time was 0.31%. The average recovery was 99.58%. Copyright © 2016 Elsevier B.V. All rights reserved.

Organic Carbon Burial in Brazilian Mangrove Sediments (Invited)

NASA Astrophysics Data System (ADS)

Sanders, C.; Smoak, J. M.; Sanders, L.; Patchineelam, S.

2010-12-01

This study reviews the organic carbon (OC) burial rates in mangrove forests, margins and mud flats in geographically distinct areas of the Brazilian coastline. We exam the burial rates, taking into account the geomorphology of each region. Our initial results indicate that the Northeastern region of Brazil is sequestering significantly more OC than in the Southeastern areas, being that the mass sediment accumulation rates remained consistent within the forests as opposed to large variations found in the mudflats. The other pertinent factor was OC content, which differed substantially in respect to region. Given that the mangrove forests of the Southeastern regions of Brazil may be more susceptible to a rising sea level, as these areas are constricted by vast mountain ranges, this work attempts to put in perspective the possible impacts of climate change on mangrove ecosystems and OC burial along the Brazilian coastal ocean. We also compare our result to global averages.

Uric acid-derived Fe3C-containing mesoporous Fe/N/C composite with high activity for oxygen reduction reaction in alkaline medium

NASA Astrophysics Data System (ADS)

Ma, Jun; Xiao, Dejian; Chen, Chang Li; Luo, Qiaomei; Yu, Yue; Zhou, Junhao; Guo, Changding; Li, Kai; Ma, Jie; Zheng, Lirong; Zuo, Xia

2018-02-01

In this work, a category of Fe3C-containing Fe/N/C mesoporous material has been fabricated by carbonizing the mixture of uric acid, Iron (Ⅲ) chloride anhydrous and carbon support (XC-72) under different pyrolysis temperature. Of all these samples, pyrolysis temperature (800 °C) becomes the most crucial factor in forming Fe3C active sites which synergizes with high content of graphitic N to catalyze oxygen reduction reaction (ORR). X-ray absorption fine structure spectroscopy (XAFS) is used to exhibit that the space structure around Fe atoms in the catalyst. This kind of catalyst possesses comparable ORR properties with commercial 20% Pt/C (onset potential is 0 V vs. Ag/AgCl in 0.1 M KOH), the average transfer electron number is 3.84 reflecting the 4-electron process. Moreover, superior stability and methanol tolerance deserve to be mentioned.

Chemical composition and source of fine and nanoparticles from recent direct injection gasoline passenger cars: Effects of fuel and ambient temperature

NASA Astrophysics Data System (ADS)

Fushimi, Akihiro; Kondo, Yoshinori; Kobayashi, Shinji; Fujitani, Yuji; Saitoh, Katsumi; Takami, Akinori; Tanabe, Kiyoshi

2016-01-01

Particle number, mass, and chemical compositions (i.e., elemental carbon (EC), organic carbon (OC), elements, ions, and organic species) of fine particles emitted from four of the recent direct injection spark ignition (DISI) gasoline passenger cars and a port fuel injection (PFI) gasoline passenger car were measured under Japanese official transient mode (JC08 mode). Total carbon (TC = EC + OC) dominated the particulate mass (90% on average). EC dominated the TC for both hot and cold start conditions. The EC/TC ratios were 0.72 for PFI and 0.88-1.0 (average = 0.92) for DISI vehicles. A size-resolved chemical analysis of a DISI car revealed that the major organic components were the C20-C28 hydrocarbons for both the accumulation-mode particles and nanoparticles. Contribution of engine oil was estimated to be 10-30% for organics and the sum of the measured elements. The remaining major fraction likely originated from gasoline fuel. Therefore, it is suggested that soot (EC) also mainly originated from the gasoline. In experiments using four fuels at three ambient temperatures, the emission factors of particulate mass were consistently higher with regular gasoline than with premium gasoline. This result suggest that the high content of less-volatile compounds in fuel increase particulate emissions. These results suggest that focusing on reducing fuel-derived EC in the production process of new cars would effectively reduce particulate emission from DISI cars.

Stages of weathering mantle formation from carbonate rocks in the light of rare earth elements (REE) and Sr-Nd-Pb isotopes

NASA Astrophysics Data System (ADS)

Hissler, Christophe; Stille, Peter

2015-04-01

Weathering mantles are widespread and include lateritic, sandy and kaolinite-rich saprolites and residuals of partially dissolved rocks. These old regolith systems have a complex history of formation and may present a polycyclic evolution due to successive geological and pedogenetic processes that affected the profile. Until now, only few studies highlighted the unusual high content of associated trace elements in weathering mantles originating from carbonate rocks, which have been poorly studied, compared to those developing on magmatic bedrocks. For instance, these enrichments can be up to five times the content of the underlying carbonate rocks. However, these studies also showed that the carbonate bedrock content only partially explains the soil enrichment for all the considered major and trace elements. Up to now, neither soil, nor saprolite formation has to our knowledge been geochemically elucidated. Therefore, the aim of this study was to examine more closely the soil forming dynamics and the relationship of the chemical soil composition to potential sources. REE distribution patterns and Sr-Nd-Pb isotope ratios have been used because they are particularly well suited to identify trace element migration, to recognize origin and mixing processes and, in addition, to decipher possible anthropogenic and/or "natural" atmosphere-derived contributions to the soil. Moreover, leaching experiments have been applied to identify mobile phases in the soil system and to yield information on the stability of trace elements and especially on their behaviour in these Fe-enriched carbonate systems. All these geochemical informations indicate that the cambisol developing on such a typical weathering mantle ("terra fusca") has been formed through weathering of a condensed Bajocian limestone-marl facies. This facies shows compared to average world carbonates important trace element enrichments. Their trace element distribution patterns are similar to those of the soil suggesting their close genetic relationships. Sr-Nd-Pb isotope data allow to identify four principal components in the soil: a silicate-rich pool at close to the surface, a leachable REE enriched pool at the bottom of the soil profile, the limestone facies on which the weathering profile developed and an anthropogenic, atmosphere-derived component detected in the soil leachates of the uppermost soil horizon. The leachable phases are mainly secondary carbonate-bearing REE phases such as bastnaesite. The isotope data and trace element distribution patterns indicate that at least four geological and environmental events impacted the chemical and isotopical compositions of the soil system since the Cretaceous.

Pyrogenic Carbon in forest soils across climate and soil property gradients in Switzerland

NASA Astrophysics Data System (ADS)

Reisser, Moritz; González Domínguez, Beatriz R.; Hagedorn, Frank; Abiven, Samuel

2016-04-01

Soil organic carbon (SOC) is an important measure for soil quality. Usually a high organic matter content in soils is favourable for most ecosystems. As a very stable component, pyrogenic organic carbon (PyC) can be of major interest to investigate to potential of organic matter, to persist very long in soils. Recent studies have shown, that the mean residence time of organic matter is not only due to its intrinsic chemical nature, but also to a variety of abiotic and biotic variables set by the ecosystem. Especially for PyC it is unclear, whether its content is related to fire regime, soil properties or other climatic conditions. In this study we wanted to investigate, how climatic and soil-related conditions are influencing the persistence of PyC in soils. Therefore we used a sample set from Swiss forest soil (n = 54), which was designed for the purpose of having most differing climatic conditions (aridity and temperature) and a large range of soil properties (pH between 3.4 and 7.6; clay content between 4.7 % and 60 %). The soils were sampled in the first 20 cm of the mineral horizon on a representative plot area of 40 x 40 m. The soils were sieved to 2 mm and dried prior to the analysis. We used the benzene polycarboxylic acids (BPCA) molecular marker method to quantify and characterize PyC in these soil samples. Despite the large span in environmental conditions, we observed rather small differences in the contribution of PyC to SOC between warmer and colder, as well as between wetter and dryer soils. The PyC content in SOC lies well in range with a global average for forest soils estimated in other studies. Stocks of PyC vary more than the content, because of the large range of SOC contents in the samples. The influence of other parameters like soil properties is still under investigation. Qualitative investigation of the BPCAs showed that the degree of condensation, defined by the relative amount of B6CA in the total BPCA, was higher in warmer soils. This might be explained by the fact that warmer conditions favour decomposition of organic matter and leave a higher relative amount of the most condensed and therefore also stable molecules.

[Effects of land use type on the distribution of organic carbon in different sized soil particles effects of land use type on the distribution of organic carbon in different sized soil particles and its relationships to herb biomass in hilly red soil region of South China].

PubMed

Li, Zhong-Wu; Guo, Wang; Wang, Xiao-Yan; Shen, Wei-Ping; Zhang, Xue; Chen, Xiao-Lin; Zhang, Yue-Nan

2012-04-01

The changes in organic carbon content in different sized soil particles under different land use patterns partly reflect the variation of soil carbon, being of significance in revealing the process of soil organic carbon cycle. Based on the long-term monitoring of soil erosion, and by the methods of soil particle size fractionation, this paper studied the effects of different land use types (wasteland, pinewood land, and grassland) on the distribution of organic carbon content in different sized soil particles and its relationships to the herb biomass. Land use type and slope position had obvious effects on the organic carbon content in different sized soil particles, and the organic carbon content was in the order of grassland > pinewood land > wasteland. The proportion of the organic carbon in different sized soil particles was mainly depended on the land use type, and had little relationships with slope position. According to the analysis of the ratio of particle-associated organic carbon to mineral-associated organic carbon (POC/MOC), the soil organic carbon in grassland was easily to be mineralized, whereas that in wasteland and pinewood land was relatively stable. On the slopes mainly in hilly red soil region, the soil organic carbon in sand fraction had great effects on herb biomass.

Estimation of black carbon content for biomass burning aerosols from multi-channel Raman lidar data

NASA Astrophysics Data System (ADS)

Talianu, Camelia; Marmureanu, Luminita; Nicolae, Doina

2015-04-01

Biomass burning due to natural processes (forest fires) or anthropical activities (agriculture, thermal power stations, domestic heating) is an important source of aerosols with a high content of carbon components (black carbon and organic carbon). Multi-channel Raman lidars provide information on the spectral dependence of the backscatter and extinction coefficients, embedding information on the black carbon content. Aerosols with a high content of black carbon have large extinction coefficients and small backscatter coefficients (strong absorption), while aerosols with high content of organic carbon have large backscatter coefficients (weak absorption). This paper presents a method based on radiative calculations to estimate the black carbon content of biomass burning aerosols from 3b+2a+1d lidar signals. Data is collected at Magurele, Romania, at the cross-road of air masses coming from Ukraine, Russia and Greece, where burning events are frequent during both cold and hot seasons. Aerosols are transported in the free troposphere, generally in the 2-4 km altitude range, and reaches the lidar location after 2-3 days. Optical data are collected between 2011-2012 by a multi-channel Raman lidar and follows the quality assurance program of EARLINET. Radiative calculations are made with libRadTran, an open source radiative model developed by ESA. Validation of the retrievals is made by comparison to a co-located C-ToF Aerosol Mass Spectrometer. Keywords: Lidar, aerosols, biomass burning, radiative model, black carbon Acknowledgment: This work has been supported by grants of the Romanian National Authority for Scientific Research, Programme for Research- Space Technology and Advanced Research - STAR, project no. 39/2012 - SIAFIM, and by Romanian Partnerships in priority areas PNII implemented with MEN-UEFISCDI support, project no. 309/2014 - MOBBE

Evaluation of Heterotrophy in in Serpentinite-Associated Waters from the Coast Range Ophiolite, Northern California, USA and the Zambales Ophiolite, Philippines

NASA Astrophysics Data System (ADS)

Scott, T. J.; Arcilla, C. A.; Cardace, D.; Hoehler, T. M.; McCollom, T. M.; Meyer-Dombard, D. R.; Schrenk, M. O.

2013-12-01

The deep biosphere in cold, dark sub-seafloor ultramafic rocks (i.e., those rocks rich in Fe and Mg) is stressed by exceedingly high pH, transient, if any, inorganic carbon availability, and little known organic carbon inventories. As a test of heterotrophic carbon use, serpentinite-associated waters (from groundwater sampling wells and associated surface seepages in tectonically uplifted mantle units in ophiolites) were tested for differences with respect to aqueous geochemistry and performance in EcoPlates™ - Biolog Inc. .. This work focuses on two field locations for water sampling: the Coast Range Ophiolite, CA, USA, and the Zambales Ophiolite, Philippines. Characteristics of each sampling site are presented (pH, mineral substrate, Ca2+/Mg2+ ratio, aqueous metal loads, etc.). Complementary EcoPlate™ results [prefabricated 96-well plates, seeded with triplicate experiments for determining microbiological community response to difference organic carbon sources; a triplicate control experiment with just water is built in to the plate also] are also presented. We found that waters from selected California [groundwater wells (7 discrete wells) and related surface seeps (5 hydrologically connected sites)] and Philippines [4 Zambales Ophiolite springs/seepages] sourced in serpentinites were analyzed. EcoPlate™ average well-color development (AWCD), which demonstrates microbial activities averaged per plate (as in Garland and Mills, 1991), differs across sites. Correlations of AWCD with environmental data (such as pH, oxidation-reduction potential or ORP, Ca2+/Mg2+ ratio, and Fe contents) are evaluated. Clarifying the geochemical-biological relationships that bear out in these analyses informs discourse on the energetic limits of life in serpentinizing systems, with relevance to ultramafic-hosted life on continents and in the seabed.

Boronization in textor

NASA Astrophysics Data System (ADS)

Winter, J.; Esser, H. G.; Könen, L.; Philipps, V.; Reimer, H.; Seggern, J. v.; Schlüter, J.; Vietzke, E.; Waelbroeck, F.; Wienhold, P.; Banno, T.; Ringer, D.; Vepřek, S.

1989-04-01

The liner and limiters of TEXTOR have been coated in situ with a boron containing carbon film using a RG discharge in a throughflow of 0.8 He + 0.1 B 2H 6 +0.1 CH 4. The average film thickness was 30-50 nm, the ratio of boron and carbon in the layer was about 1:1 according to Auger Electron Spectroscopy. Subsequent tokamak discharges are characterized by a small fraction of radiated power (< 0.3) even during high power ICRF heating (2.6 MW, 1.6 s). A concomitant strong increase of the convective power loading of the limiters is observed. Values of Z eff lower than 1.2 are derived from conductivity measurements. The most prominent change in the impurity concentration compared to good conditions in a carbonized surrounding is measured for oxygen. The value OVI/ n¯e of the OVI intensity normalized to the averaged plasma density overlinene decreases by more than a factor of four. The decrease in the oxygen content manifests itself also as a reduction of the CO and CO 2 partial pressures measured during and after the discharge with a sniffer probe. The carbon levels are reduced by a factor of about two as measured by the normalized intensity CII/ overlinene of the CII line and via the ratio of the C fluxes and deuterium fluxes measured at the limiter (CI/D α). The wall shows a pronounced sorption of hydrogen from the plasma, easing the density control and the establishment of low recycling conditions. The beneficial conditions did not show a significant deterioration during more than 200 discharges, including numerous shots at ICRH power levels > 2 MW.

Riverine input of organic carbon and nitrogen in water-sediment system from the Yellow River estuary reach to the coastal zone of Bohai Sea, China

NASA Astrophysics Data System (ADS)

Wang, Chuanyuan; Lv, Yingchun; Li, Yuanwei

2018-04-01

The temporal-spatial distribution of the carbon and nitrogen contents and their isotopic compositions of suspended matter and sediments from the Yellow River estuary reach (YRER), the estuary to the offshore area were measured to identify the source of organic matter. The higher relative abundances of suspended and sedimentary carbon and nitrogen (POC, TOC, PN and TN) in the offshore marine area compared to those of the riverine and estuarine areas may be due to the cumulative and biological activity impact. The organic matter in surface sediments of YRER, the estuary and offshore area of Bohai Sea is basically the mixture of continental derived material and marine material. The values of δ13Csed fluctuate from values indicative of a land source (- 22.50‰ ± 0.31) to those indicative of a sea source (- 22.80‰ ± 0.38), which can be attributed to the fine particle size and decrease in terrigenous inputs to the offshore marine area. Contrary to the slight increase of POC and PN during the dry season, TOC and TN contents of the surface sediments during the flood season (October) were higher than those during the dry season (April). The seasonal differences in water discharge and suspended sediment discharge of the Yellow River Estuary may result in seasonal variability in TOC, POC, TN and PN concentrations in some degree. Overall, the surface sediments in the offshore area of Bohai Sea are dominated by marine derived organic carbon, which on average, accounts for 58-82% of TOC when a two end-member mixing model is applied to the isotopic data.

Petrography and geochemistry of the Middle Devonian coal from Luquan, Yunnan Province, China

USGS Publications Warehouse

Dai, S.; Han, D.; Chou, C.-L.

2006-01-01

Coals from Luquan, Yunnan Province, China, have high contents of cutinite and microsporinite, with an average of 55 and 33.5 vol%, respectively, (on a mineral-free basis). The coals are classified as cutinitic liptobiolith, sporinite-rich durain, cutinite-rich durain, and sporinitic liptobiolith. These four liptinite-rich coals are often interlayered within the coal bed section and vary transversely within the coal bed. The vitrinite content varies from as low as 1.6-20.5% (mineral-free basis), and it is dominated by collodetrinite, collotelinite, and corpogelinite. The maceral composition may be attributed to the type of the peat-forming plant communities. Moreover, the Luquan coals are characterized by high contents of volatile matter, hydrogen, and oxygen, and the high values of the atomic hydrogen to carbon ratio as a result of the maceral composition. As compared with the common Chinese coals and the upper continental crust, the Luquan coals are enriched in Li, B, Cu, Ga, Se, Rb, Mo, Ba, Pb, Bi, and U, with averages of 99.9, 250, 111, 24.4, 4.55, 130, 58.8, 1276, 162, 3.85, and 34.1 ??g/g, respectively. The SEM-EDX results show that V, Cr, Ga, and Rb occur mainly in clay minerals, and Cu and Pb are associated with clay minerals and pyrite, and Mo and U are mainly in clay minerals and organic matter. Barite and clay minerals are the main carrier of barium. The high B and U contents are probably resulted from deep seawater influence during coal formation. ?? 2005 Elsevier Ltd. All rights reserved.

Synthesis and Characterization of Solution and Melt Processible Poly(Acrylonitrile-Co-Methyl Acrylate) Statistical Copolymers

NASA Astrophysics Data System (ADS)

Pisipati, Padmapriya

Polyacrylonitrile (PAN) and its copolymers are used in a wide variety of applications ranging from textiles to purification membranes, packaging material and carbon fiber precursors. High performance polyacrylonitrile copolymer fiber is the most dominant precursor for carbon fibers. Synthesis of very high molecular weight poly(acrylonitrile-co-methyl acrylate) copolymers with weight average molecular weights of at least 1.7 million g/mole were synthesized on a laboratory scale using low temperature, emulsion copolymerization in a closed pressure reactor. Single filaments were spun via hybrid dry-jet gel solution spinning. These very high molecular weight copolymers produced precursor fibers with tensile strengths averaging 954 MPa with an elastic modulus of 15.9 GPa (N = 296). The small filament diameters were approximately 5 im. Results indicated that the low filament diameter that was achieved with a high draw ratio, combined with the hybrid dry-jet gel spinning process lead to an exponential enhancement of the tensile properties of these fibers. Carbon fibers for polymer matrix composites are currently derived from polyacrylonitrile copolymer fiber precursors where solution spinning accounts for ˜40 % of the total fiber production cost. To expand carbon fiber applications into the automotive industry, the cost of the carbon fiber needs to be reduced from 8 to ˜3-5. In order to develop an alternative melt processing route several benign plasticizers have been investigated. A low temperature, persulfate-metabisulfite initiated emulsion copolymerization was developed to synthesize poly(acrylonitrile-co-methyl acrylate) copolymers with acrylonitrile contents between 91-96 wt% with a molecular weight range of 100-200 kg/mol. This method was designed for a potential industrial scale up. Furthermore, water was investigated as a potential melting point depressant for these copolymers. Twenty-five wt% water lead to a decrease in the Tm of a 93/7 wt/wt % poly(acrylonitrile-co-methyl acrylate) of Mw = 200 kg/mol to 160 0C as measured via DSC. Glycerin, ethylene glycol and glycerin/water combinations were investigated as potential plasticizers for high molecular weight (˜200,000 g/mol), high acrylonitrile (93-96 mole:mole %) content poly(acrylonitrile-co-methyl acrylate) statistical copolymers. Pure glycerin (25 wt %) induced crystallization followed by a reduced "Tm" of about 213 0C via DSC. However this composition did not melt process well. A lower M W (˜35 kg/mol) copolymer did extrude with no apparent degradation. Our hypothesis is that the hydroxyl groups in glycerin (or water) disrupt the strong dipole-dipole interactions between the chains enabling the copolymer endothermic transition (Tm) to be reduced and enable melting before the onset of degradation. Additionally high molecular weight (Mw = 200-230 kg/mol) poly(acrylonitrile-co-methyl acrylate) copolymers with lower acrylonitrile content (82-85 wt %) were synthesized via emulsion copolymerization and successfully melt pressed. These materials will be further investigated for their utility in packaging applications.

[Characteristics of soil organic carbon and enzyme activities in soil aggregates under different vegetation zones on the Loess Plateau].

PubMed

Li, Xin; Ma, Rui-ping; An, Shao-shan; Zeng, Quan-chao; Li, Ya-yun

2015-08-01

In order to explore the distribution characteristics of organic carbon of different forms and the active enzymes in soil aggregates with different particle sizes, soil samples were chosen from forest zone, forest-grass zone and grass zone in the Yanhe watershed of Loess Plateau to study the content of organic carbon, easily oxidized carbon, and humus carbon, and the activities of cellulase, β-D-glucosidase, sucrose, urease and peroxidase, as well as the relations between the soil aggregates carbon and its components with the active soil enzymes were also analyzed. It was showed that the content of organic carbon and its components were in order of forest zone > grass zone > forest-grass zone, and the contents of three forms of organic carbon were the highest in the diameter group of 0.25-2 mm. The content of organic carbon and its components, as well as the activities of soil enzymes were higher in the soil layer of 0-10 cm than those in the 10-20 cm soil layer of different vegetation zones. The activities of cellulase, β-D-glucosidase, sucrose and urease were in order of forest zone > grass zone > forest-grass zone. The peroxidase activity was in order of forest zone > forest-grass zone > grass zone. The activities of various soil enzymes increased with the decreasing soil particle diameter in the three vegetation zones. The activities of cellulose, peroxidase, sucrose and urease had significant positive correlations with the contents of various forms of organic carbon in the soil aggregates.

Variations on morphology and elemental composition of mineral dust particles from local, regional, and long-range transport meteorological scenarios

NASA Astrophysics Data System (ADS)

Coz, Esther; Gómez-Moreno, Francisco J.; Casuccio, Gary S.; ArtíñAno, BegoñA.

2010-06-01

Mineral dust is the second major source of PM10 in Madrid, reaching up to 80% of the PM10 mass during certain long-range dust transport events. Three different types of scenarios have been found to be associated with the high particle concentration episodes in the city: local anthropogenic, regional recirculation, and African dust transport processes. The present study focuses on the characterization of the individual mineral dust particles related to some chemical and morphological features during these three types of episodes, with special attention to local and regional episodes. To achieve this purpose, four different samples were selectively collected during the 2004-2005 period campaigns, one corresponding to each type of scenario and other sample from an Atlantic ventilated one. Meteorological situation, dust source identification, impact on ambient concentrations, size range distribution, and particle individual analysis have been characterized for each of them. Elemental composition and morphology of more than 30,000 mineral particles were analyzed by computer-controlled scanning electron microscopy. Particles were grouped into clusters based on their elemental composition, and the aspect ratio (AR) of each cluster or category was compared for each type of episode. The AR was related to the mineralogical crystal structure of each chemical cluster. The dates chosen for microscopy analysis were in good agreement in size distribution and chemical composition with the average of the dates in the entire campaign and with those from previous campaigns. Major differences between local/regional and long-range transported mineral dust were found in the relative abundance between carbonates and silicates, with much higher abundance of calcium carbonates in the first ones. These differences between silicate and carbonate contents were consistent with the results found in previous campaigns and were directly related to the composition of the parent topsoil by studying the Ca/Si ratios of similar episodes recorded all over the Iberian Peninsula. Differences in morphology were also found for these scenarios. The predominance of calcium carbonate under regional and local influence is scientifically relevant since this mineral is known to react with both SO2 and HNO3 in the atmosphere. Larger average AR values were found for dust particles from long-range transport, and smaller average AR values were found for particles from local and regional resuspended dust. The increasing average AR value has been linked to the silicate cluster presence, whereas a reduction has been observed within the carbonate cluster.

7 CFR 51.2548 - Average moisture content determination.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 2 2010-01-01 2010-01-01 false Average moisture content determination. 51.2548... moisture content determination. (a) Determining average moisture content of the lot is not a requirement of... connection with grade analysis or as a separate determination. (b) Nuts shall be obtained from a randomly...

[Vertical distribution of soil active carbon and soil organic carbon storage under different forest types in the Qinling Mountains].

PubMed

Wang, Di; Geng, Zeng-Chao; She, Diao; He, Wen-Xiang; Hou, Lin

2014-06-01

Adopting field investigation and indoor analysis methods, the distribution patterns of soil active carbon and soil carbon storage in the soil profiles of Quercus aliena var. acuteserrata (Matoutan Forest, I), Pinus tabuliformis (II), Pinus armandii (III), pine-oak mixed forest (IV), Picea asperata (V), and Quercus aliena var. acuteserrata (Xinjiashan Forest, VI) of Qinling Mountains were studied in August 2013. The results showed that soil organic carbon (SOC), microbial biomass carbon (MBC), dissolved organic carbon (DOC), and easily oxidizable carbon (EOC) decreased with the increase of soil depth along the different forest soil profiles. The SOC and DOC contents of different depths along the soil profiles of P. asperata and pine-oak mixed forest were higher than in the other studied forest soils, and the order of the mean SOC and DOC along the different soil profiles was V > IV > I > II > III > VI. The contents of soil MBC of the different forest soil profiles were 71.25-710.05 mg x kg(-1), with a content sequence of I > V > N > III > II > VI. The content of EOC along the whole soil profile of pine-oak mixed forest had a largest decline, and the order of the mean EOC was IV > V> I > II > III > VI. The sequence of soil organic carbon storage of the 0-60 cm soil layer was V > I >IV > III > VI > II. The MBC, DOC and EOC contents of the different forest soils were significanty correlated to each other. There was significant positive correlation among soil active carbon and TOC, TN. Meanwhile, there was no significant correlation between soil active carbon and other soil basic physicochemical properties.

Humus and energy balances and greenhouse gas emissions with compost fertilization in organic farming compared with mineral fertilization

NASA Astrophysics Data System (ADS)

Erhart, Eva; Schmid, Harald; Hülsbergen, Kurt-Jürgen; Hartl, Wilfried

2015-04-01

Humus and energy balances and greenhouse gas emissions with compost fertilization in organic farming compared with mineral fertilization E. Erhart, H. Schmid, K.-J. Hülsbergen, W. Hartl The positive effects of compost fertilization on soil humus with their associated benefits for soil quality are well-established. The aim of the present study was to assess the effect of compost fertilization on humus and energy balances and greenhouse gas emissions and to compare the results of the humus balances with the changes in soil organic carbon contents measured in the soil of the experimental field. In order to assess the effects of compost use in organic farming as compared to conventional farming practice using mineral fertilizers, the field experiment with compost fertilization 'STIKO' was set up in 1992 near Vienna, Austria, on a Molli-gleyic Fluvisol. It included three treatments with compost fertilization (C1, C2 and C3 with 8, 14 and 20 t ha-1 y-1 f. m. on average of 14 years), three treatments with mineral nitrogen fertilization (N1, N2 and N3 with 29, 46 and 63 kg N ha-1 y 1 on average) and an unfertilized control (0) in six replications in a latin rectangle design. In the field trial, biowaste compost from the composting plant of the City of Vienna was used. Data from the field experiment (from 14 experimental years) were fed into the model software REPRO to calculate humus and energy balances and greenhouse gas emissions. The model software REPRO (REPROduction of soil fertility) couples the balancing of C, N and energy fluxes. For the determination of the net greenhouse effect, REPRO performs calculations of C sequestration in the soil, CO2 emissions from the use of fossil energy and N2O emissions from the soil. Humus balances showed that compost fertilization at a rate of 8 t ha-1 y-1 (C1) resulted in a positive humus balance of +115 kg C ha-1 y-1. With 14 and 20 t ha-1 y-1 compost (C2 and C3), respectively, humus accumulated at rates of 558 and 1021 kg C ha-1 y-1. With mineral fertilization at rates of 29 - 63 kg N ha-1 y-1 (N1 - N3), balances were moderately negative ( 169 to -227 kg C ha-1 y-1), while a clear humus deficit of 457 kg C ha-1 y-1 showed in the unfertilized control. Compared with measured soil organic carbon data REPRO predicted soil organic carbon contents fairly well with the exception of the treatments with high compost rates. Here REPRO clearly overestimated soil organic carbon contents for this site. Energy efficiency, as described by the output/input ratio, was highest in the control, followed by C1. Mineral fertilization treatment N3 was most energy intensive. The greenhouse gas balance indicated net carbon sequestration already with medium compost rates (C2), and net carbon sequestration of 1700 kg CO2-eq ha-1 y-1 in C3. Mineral fertilization yielded net greenhouse gas emissions of around 2000 kg CO2-eq ha-1 y 1. The highest greenhouse gas emissions had the unfertilized control due to the degradation of soil organic matter and lowest organic matter input. These findings underline that compost fertilization holds a high potential for carbon sequestration and for the reduction of greenhouse gas emissions.

The heterogeneity of segmental dynamics of filled EPDM by (1)H transverse relaxation NMR.

PubMed

Moldovan, D; Fechete, R; Demco, D E; Culea, E; Blümich, B; Herrmann, V; Heinz, M

2011-01-01

Residual second moment of dipolar interactions M(2) and correlation time segmental dynamics distributions were measured by Hahn-echo decays in combination with inverse Laplace transform for a series of unfilled and filled EPDM samples as functions of carbon-black N683 filler content. The fillers-polymer chain interactions which dramatically restrict the mobility of bound rubber modify the dynamics of mobile chains. These changes depend on the filler content and can be evaluated from distributions of M(2). A dipolar filter was applied to eliminate the contribution of bound rubber. In the first approach the Hahn-echo decays were fitted with a theoretical relationship to obtain the average values of the (1)H residual second moment and correlation time <τ(c)>. For the mobile EPDM segments the power-law distribution of correlation function was compared to the exponential correlation function and found inadequate in the long-time regime. In the second approach a log-Gauss distribution for the correlation time was assumed. Furthermore, using an averaged value of the correlation time, the distributions of the residual second moment were determined using an inverse Laplace transform for the entire series of measured samples. The unfilled EPDM sample shows a bimodal distribution of residual second moments, which can be associated to the mobile polymer sub-chains (M(2) ≅ 6.1 rad (2) s(-2)) and the second one associated to the dangling chains M(2) ≅ 5.4 rad(2) s(-2)). By restraining the mobility of bound rubber, the carbon-black fillers induce diversity in the segmental dynamics like the apparition of a distinct mobile component and changes in the distribution of mobile and free-end polymer segments. Copyright © 2010 Elsevier Inc. All rights reserved.

The heterogeneity of segmental dynamics of filled EPDM by 1H transverse relaxation NMR

NASA Astrophysics Data System (ADS)

Moldovan, D.; Fechete, R.; Demco, D. E.; Culea, E.; Blümich, B.; Herrmann, V.; Heinz, M.

2011-01-01

Residual second moment of dipolar interactions M∼2 and correlation time segmental dynamics distributions were measured by Hahn-echo decays in combination with inverse Laplace transform for a series of unfilled and filled EPDM samples as functions of carbon-black N683 filler content. The fillers-polymer chain interactions which dramatically restrict the mobility of bound rubber modify the dynamics of mobile chains. These changes depend on the filler content and can be evaluated from distributions of M∼2. A dipolar filter was applied to eliminate the contribution of bound rubber. In the first approach the Hahn-echo decays were fitted with a theoretical relationship to obtain the average values of the 1H residual second moment and correlation time <τc>. For the mobile EPDM segments the power-law distribution of correlation function was compared to the exponential correlation function and found inadequate in the long-time regime. In the second approach a log-Gauss distribution for the correlation time was assumed. Furthermore, using an averaged value of the correlation time, the distributions of the residual second moment were determined using an inverse Laplace transform for the entire series of measured samples. The unfilled EPDM sample shows a bimodal distribution of residual second moments, which can be associated to the mobile polymer sub-chains (M∼2≅6.1 rad s) and the second one associated to the dangling chains M∼2≅5.4 rad s). By restraining the mobility of bound rubber, the carbon-black fillers induce diversity in the segmental dynamics like the apparition of a distinct mobile component and changes in the distribution of mobile and free-end polymer segments.

Diatom assemblages from a turbid coastal plain estuary: Río de la Plata (South America)

NASA Astrophysics Data System (ADS)

Licursi, Magdalena; Sierra, María Victoria; Gómez, Nora

2006-08-01

The Río de la Plata is located on the East coast of South America and is a shallow, large-scale, turbid coastal plain estuary that covers an approximate area of 35,000 km 2. Despite the socio-economic importance of the Río de la Plata, studies related to the biological aspects of this ecosystem are scarce, particularly in the freshwater tidal zone. The objective of this study was to explore the diatom composition and distribution of density, biomass and empty frustules along the fluvial-mixohaline axis. Furthermore it was to analyze the spatial succession of diatom assemblages and the environmental variables during an extensive sampling carried out during spring 2001. Two replicate sub-surface water samples were collected at 29 sites for quantitative analysis of phytoplankton. The greatest number of species, mainly pennate taxa, were observed in the freshwater tidal zone. The average density of the diatoms was 59 cells ml - 1 . Chains or filaments of centric diatoms were frequent and dominant in the samples along the fluvial-mixohaline axis. The carbon content of the diatoms increased downstream, with an average value of 2.5 μg C l - 1 in the freshwater tidal zone and 4.4 μg C l - 1 in the mixohaline zone. Diatoms supplied 65% of the total phytoplankton carbon content in the freshwater tidal zone and reached 17% in the mixohaline zone. Canonical Correspondence Analysis (CCA) allowed us to identify two species assemblages in the Río de la Plata differentiated mainly by salinity, pH and silicate gradients. In our study species exclusive to brackish waters were not identified, but some freshwater and marine taxa with wide ranges of salinity tolerance were observed.

Influences of Forest Tree Species and Early Spring Temperature on Surface-Atmosphere Transfers of Water and Carbon in the Northeastern U.S.

NASA Astrophysics Data System (ADS)

Hadley, J. L.; Kuzeja, P.; Mulcahy, T.; Singh, S.

2008-12-01

Influences of Forest Tree Species and Early Spring Temperature on Surface-Atmosphere Transfers of Water and Carbon in the Northeastern U.S. Julian Hadley, Paul Kuzeja, Safina Singh and Thomas Mulcahy Transfers of water vapor from terrestrial ecosystems to the atmosphere affect regional hydrology, weather and climate over short time scales, and forest-atmosphere CO2 exchange affects global climate over long timescales. To better understand these effects for forests dominated by two very different tree species, we measured forest-atmosphere water vapor and CO2 transfers by the eddy flux technique to at two sites in central Massachusetts USA for three years. Average annual evapotranspiration (ET) for a young deciduous forest dominated by red oak (Quercus rubra L., the most abundant tree species in the area), was about 430 mm or 25 percent greater than for a coniferous forest dominated by 100 to 230 year old eastern hemlock (Tsuga canadensis L.). The difference in ET was most pronounced in July and August when the deciduous forest lost about 50 percent more water by ET in the average year (192 mm for oak forest versus 130 mm for hemlock). These data indicate that if deciduous trees with similar physiology to red oak replace hemlocks, summertime ET will increase while summer streamflow, soil water content and the extent of year- round wetlands will decrease. Increased summertime ET should also lead to slightly higher regional atmospheric humidity and precipitation. Hemlock-to-deciduous forest conversion has occurred from North Carolina to southern New England and is continuing northward as a lethal insect pest, the hemlock woolly adelgid (Adelges tsugae Annand) continues to kill hemlocks. Average annual carbon storage for the old hemlock forest in our study was about 3.3 Mg C/ha, nearly equal to the average for the deciduous forest, 3.5 Mg C/ha. This calls into question ecological theory that predicts large declines in the rate of carbon uptake for old forests, and indicates that annual carbon storage will not necessarily increase over the long term after hemlock trees are killed by the hemlock woolly adelgid and replaced by deciduous species. Maximum monthly carbon storage in the hemlock forest occurred in spring (April and May) and was enhanced by early soil thawing and cessation of nighttime frost. This pattern is probably common to many evergreen conifers in the northeastern U.S., so climate warming that includes an earlier end to freezing temperatures in spring should increase C storage by conifer forests in the northeastern U.S. - unless this effect is canceled out by reduced C uptake or enhanced C loss due to changes in summer and fall climate.

Global Distribution of Pyrogenic Carbon

NASA Astrophysics Data System (ADS)

Reisser, Moritz; Abiven, Samuel; Schmidt, Michael W. I.

2016-04-01

Pyrogenic Carbon (PyC) is ubiquitous in the environment and represents presumably one of the most stable compounds of the total organic carbon. Due to its persistence in the soil, it might play an important role in the global carbon cycle. In order to model future CO2 emissions from soils it is thus crucial to know where and how much of PyC exists on a global scale. Yet, only rough estimates for global PyC stocks in soils could be made, and even less is known about the distribution across ecosystems. Therefore we propose here literature analysis of data on PyC concentrations and stocks worldwide. We extracted PyC values in soils from the literature (n = 600) and analysed the percentage of PyC in the soil organic carbon (SOC) as a function of climate (temperature, precipitation), soil parameters (pH, clay content), fire characteristics (fire frequency and fire regime) and land use. Overall, the average contribution of PyC to SOC was 13 %, ranging from 0.1 % up to 60 %. We observed that the PyC content was significantly higher with high clay content, higher pH, and in cultivated land as compared to forest and grassland. We did not observe any relationships between fire activity, frequency or intensity and PyC % at a global scale. When the fire regime was monitored on site (only 12 % of the data we collected), we observed higher PyC concentrations with higher fire frequencies. We hypothesise that the resolution of global fire datasets is neither temporally nor spatially high enough to explain the very local fire history of the soil samples. Data points were not homogeneously distributed on the globe, but rather aggregated in places like Central Europe, the Russian Steppe or North America. Therefore, a global interpolation is not directly possible. We modelled PyC concentrations, based on the five most significant parameters, which were clay content, pH, mean annual temperature and precipitation as well as land use. We then predicted worldwide PyC using global datasets existing for these five variables. We present a global map of PyC concentrations as well as it stocks. In arid ecosystems, where SOC is generally low, stocks of PyC are also low, even though concentrations can be very high. On the other hand, stocks are mostly very large in temperate and boreal ecosystems, even if concentrations are rather low, because total SOC stocks are very high there. Integrating our modelled data, we result in a total global stock of about 230 Pg PyC, corresponding to about 10 % of the total soil organic carbon stock. This value lies well in range with current rule-of-thump estimates of previous studies.

Experimental determination of CO2 content at graphite saturation along a natural basalt-peridotite melt join: Implications for the fate of carbon in terrestrial magma oceans

NASA Astrophysics Data System (ADS)

Duncan, Megan S.; Dasgupta, Rajdeep; Tsuno, Kyusei

2017-05-01

Knowledge of the carbon carrying capacity of peridotite melt at reducing conditions is critical to constrain the mantle budget and planet-scale distribution of carbon set at early stage of differentiation. Yet, neither measurements of CO2 content in reduced peridotite melt nor a reliable model to extrapolate the known solubility of CO2 in basaltic (mafic) melt to solubility in peridotitic (ultramafic) melt exist. There are several reasons for this gap; one reason is due to the unknown relative contributions of individual network modifying cations, such as Ca2+ versus Mg2+, on carbonate dissolution particularly at reducing conditions. Here we conducted high pressure, temperature experiments to estimate the CO2 contents in silicate melts at graphite saturation over a compositional range from natural basalts toward peridotite at a fixed pressure (P) of 1.0 GPa, temperature (T) of 1600 °C, and oxygen fugacity (log ⁡ fO2 ∼ IW + 1.6). We also conducted experiments to determine the relative effects of variable Ca and Mg contents in mafic compositions on the dissolution of carbonate. Carbon in quenched glasses was measured and characterized using Fourier transform infrared spectroscopy (FTIR) and Raman Spectroscopy and was found to be dissolved as carbonate (CO32-). The FTIR spectra showed CO32- doublets that shifted systematically with the MgO and CaO content of silicate melts. Using our data and previous work we constructed a new composition-based model to determine the CO2 content of ultramafic (peridotitic) melt representative of an early Earth, magma ocean composition at graphite saturation. Our data and model suggest that the dissolved CO2 content of reduced, peridotite melt is significantly higher than that of basaltic melt at shallow magma ocean conditions; however, the difference in C content between the basaltic and peridotitic melts may diminish with depth as the more depolymerized peridotite melt is more compressible. Using our model of CO2 content at graphite saturation as a function of P-T-fO2-melt composition, we predict that a superliquidus shallow magma ocean should degas CO2. Whereas if the increase of fO2 with depth is weak, a magma ocean may ingas a modest amount of carbon during crystallization. Further, using the carbon content of peridotite melt at log ⁡ fO2 of IW and the knowledge of C content of Fe-rich alloy melt, we also consider the core-mantle partitioning of carbon, showing that DCmetal/peridotite of a shallow magma ocean is generally higher than previously estimated.

Carbon accumulation in peatlands of West Siberia over the last 2000 years

NASA Astrophysics Data System (ADS)

Beilman, David W.; MacDonald, Glen M.; Smith, Laurence C.; Reimer, Paula J.

2009-03-01

We use a network of cores from 77 peatland sites to determine controls on peat C content and peat C accumulation over the last 2000 years (since 2 ka) across Russia's West Siberian Lowland (WSL), the world's largest wetland region. Our results show a significant influence of fossil plant composition on peat C content, with peats dominated by Sphagnum having a lower C content. Radiocarbon-derived C accumulation since 2 ka at 23 sites is highly variable from site to site, but displays a significant N-S trend of decreasing accumulation at higher latitudes. Northern WSL peatlands show relatively small C accumulation of 7 to 35 kg C m-2 since 2 ka. In contrast, peatlands south of 60°N show larger accumulation of 42 to 88 kg C m-2. Carbon accumulation since 2 ka varies significantly with modern mean annual air temperature, with maximum C accumulation found between -1 and 0°C. Rates of apparent C accumulation since 2 ka show no significant relationship to long-term Holocene averages based on total C accumulation. A GIS-based extrapolation of our site data suggests that a substantial amount (˜40%) of total WSL peat C has accumulated since 2 ka, with much of this accumulation south of 60°N. The large peatlands in the southern WSL may be an important component of the Eurasian terrestrial C sink, and future warming could result in a shift northward in long-term WSL C sequestration.

Particulate sulfur-containing lipids: Production and cycling from the epipelagic to the abyssopelagic zone

NASA Astrophysics Data System (ADS)

Gašparović, Blaženka; Penezić, Abra; Frka, Sanja; Kazazić, Saša; Lampitt, Richard S.; Holguin, F. Omar; Sudasinghe, Nilusha; Schaub, Tanner

2018-04-01

There are major gaps in our understanding of the distribution and role of lipids in the open ocean especially with regard to sulfur-containing lipids (S-lipids). Here, we employ a powerful analytical approach based on high resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) to elucidate depth-related S-lipid production and molecular transformations in suspended particulate matter from the Northeast Atlantic Ocean in this depth range. We show that within the open-ocean environment S-lipids contribute up to 4.2% of the particulate organic carbon, and that up to 95% of these compounds have elemental compositions that do not match those found in the Nature Lipidomics Gateway database (termed "novel"). Among the remaining 5% of lipids that match the database, we find that sulphoquinovosyldiacylglycerol (SQDG) are efficiently removed while sinking through the mesopelagic zone. The relative abundance of other assigned lipids (sulphoquinovosylmonoacylglycerol (SQMG), sulfite and sulfate lipids, Vitamin D2 and D3 derivatives, and sphingolipids) did not change substantially with depth. The novel S-lipids, represented by hundreds of distinct elemental compositions (160-300 molecules at any one depth), contribute increasingly to the lipid and particulate organic matter pools with increased depth. Depth-related transformations cause (i) incomplete degradation/transformation of unsaturated S-lipids which leads to the depth-related accumulation of the refractory saturated compounds with reduced molecular weight (average 455 Da) and (ii) formation of highly unsaturated S-lipids (average abyssopelagic molecular double bond equivalents, DBE=7.8) with lower molecular weight (average 567 Da) than surface S-lipids (average 592 Da). A depth-related increase in molecular oxygen content is observed for all novel S-lipids and indicates that oxidation has a significant role in their transformation while (bio)hydrogenation possibly impacts the formation of saturated compounds. The instrumentation approach applied here represents a step change in our comprehension of marine S-lipid diversity and the potential role of these compounds in the oceanic carbon cycle. We describe a very much higher number of compounds than previously reported, albeit at the level of elemental composition and fold-change quantitation with depth, rather than isomeric confirmation and absolute quantitation of individual lipids. We emphasize that saturated S-lipids have the potential to transfer carbon from the upper ocean to depth and hence are significant vectors for carbon sequestration.

Effect of Different Fertilizer Application on the Soil Fertility of Paddy Soils in Red Soil Region of Southern China

PubMed Central

Dong, Wenyi; Zhang, Xinyu; Wang, Huimin; Dai, Xiaoqin; Sun, Xiaomin; Qiu, Weiwen; Yang, Fengting

2012-01-01

Appropriate fertilizer application is an important management practice to improve soil fertility and quality in the red soil regions of China. In the present study, we examined the effects of five fertilization treatments [these were: no fertilizer (CK), rice straw return (SR), chemical fertilizer (NPK), organic manure (OM) and green manure (GM)] on soil pH, soil organic carbon (SOC), total nitrogen (TN), C/N ratio and available nutrients (AN, AP and AK) contents in the plowed layer (0–20 cm) of paddy soil from 1998 to 2009 in Jiangxi Province, southern China. Results showed that the soil pH was the lowest with an average of 5.33 units in CK and was significantly higher in NPK (5.89 units) and OM (5.63 units) treatments (P<0.05). The application of fertilizers have remarkably improved SOC and TN values compared with the CK, Specifically, the OM treatment resulted in the highest SOC and TN concentrations (72.5% and 51.2% higher than CK) and NPK treatment increased the SOC and TN contents by 22.0% and 17.8% compared with CK. The average amounts of C/N ratio ranged from 9.66 to 10.98 in different treatments, and reached the highest in OM treatment (P<0.05). During the experimental period, the average AN and AP contents were highest in OM treatment (about 1.6 and 29.6 times of that in the CK, respectively) and second highest in NPK treatment (about 1.2 and 20.3 times of that in the CK). Unlike AN and AP, the highest value of AK content was observed in NPK treatments with 38.10 mg·kg−1. Thus, these indicated that organic manure should be recommended to improve soil fertility in this region and K fertilizer should be simultaneously applied considering the soil K contents. Considering the long-term fertilizer efficiency, our results also suggest that annual straw returning application could improve soil fertility in this trial region. PMID:23028550

Preparation of Activated Carbon from Palm Shells Using KOH and ZnCl2 as the Activating Agent

NASA Astrophysics Data System (ADS)

Yuliusman; Nasruddin; Afdhol, M. K.; Amiliana, R. A.; Hanafi, A.

2017-07-01

Palm shell is a potential source of raw materials for the produce of activated carbon as biosorbent for quite large numbers. The purpose of this study is to produce activated carbon qualified Indonesian Industrial Standard (SNI), which will be used as biosorbent to purify the impurities in the off gas petroleum refinery products. Stages of manufacture of activated carbon include carbonization, activation of chemistry and physics. Carbonization of activated carbon is done at a temperature of 400°C followed by chemical activation with active agent KOH and ZnCl2. Then the physical activation is done by flowing N2 gas for 1 hour at 850°C and followed by gas flow through the CO2 for 1 hour at 850°C. Research results indicate that activation of the active agent KOH produce activated carbon is better than using the active agent ZnCl2. The use of KOH as an active agent to produce activated carbon with a water content of 13.6%, ash content of 9.4%, iodine number of 884 mg/g and a surface area of 1115 m2/g. While the use of ZnCl2 as the active agent to produce activated carbon with a water content of 14.5%, total ash content of 9.0%, iodine number 648 mg/g and a surface area of 743 m2/g.

Influence of carbon content on the copper-telluride phase formation and on the resistive switching behavior of carbon alloyed Cu-Te conductive bridge random access memory cells

NASA Astrophysics Data System (ADS)

Devulder, Wouter; Opsomer, Karl; Franquet, Alexis; Meersschaut, Johan; Belmonte, Attilio; Muller, Robert; De Schutter, Bob; Van Elshocht, Sven; Jurczak, Malgorzata; Goux, Ludovic; Detavernier, Christophe

2014-02-01

In this paper, we investigate the influence of the carbon content on the Cu-Te phase formation and on the resistive switching behavior in carbon alloyed Cu0.6Te0.4 based conductive bridge random access memory (CBRAM) cells. Carbon alloying of copper-tellurium inhibits the crystallization, while attractive switching behavior is preserved when using the material as Cu-supply layer in CBRAM cells. The phase formation is first investigated in a combinatorial way. With increasing carbon content, an enlargement of the temperature window in which the material stays amorphous was observed. Moreover, if crystalline phases are formed, subsequent phase transformations are inhibited. The electrical switching behavior of memory cells with different carbon contents is then investigated by implementing them in 580 μm diameter dot TiN/Cu0.6Te0.4-C/Al2O3/Si memory cells. Reliable switching behavior is observed for carbon contents up to 40 at. %, with a resistive window of more than 2 orders of magnitude, whereas for 50 at. % carbon, a higher current in the off state and only a small resistive window are present after repeated cycling. This degradation can be ascribed to the higher thermal and lower drift contribution to the reset operation due to a lower Cu affinity towards the supply layer, leading cycle-after-cycle to an increasing amount of Cu in the switching layer, which contributes to the current. The thermal diffusion of Cu into Al2O3 under annealing also gives an indication of the Cu affinity of the source layer. Time of flight secondary ion mass spectroscopy was used to investigate this migration depth in Al2O3 before and after annealing, showing a higher Cu, Te, and C migration for high carbon contents.

Carbon footprint of dairy goat milk production in New Zealand.

PubMed

Robertson, Kimberly; Symes, Wymond; Garnham, Malcolm

2015-07-01

The aim of this study was to assess the cradle-to-farm gate carbon footprint of indoor and outdoor dairy goat farming systems in New Zealand, identifying hotspots and discussing variability and methodology. Our study was based on the International Organization for Standardization standards for life cycle assessment, although only results for greenhouse gas emissions are presented. Two functional units were included: tonnes of CO2-equivalents (CO2e) per hectare (ha) and kilograms of CO2e per kilogram of fat- and protein-corrected milk (FPCM). The study covered 5 farms, 2 farming systems, and 3yr. Two methods for the calculation of enteric methane emissions were assessed. The Lassey method, as used in the New Zealand greenhouse gas inventory, provided a more robust estimate of emissions from enteric fermentation and was used in the final calculations. The alternative dry matter intake method was shown to overestimate emissions due to use of anecdotal assumptions around actual consumption of feed. Economic allocation was applied to milk and co-products. Scenario analysis was performed on the allocation method, nitrogen content of manure, manure management, and supplementary feed choice. The average carbon footprint for the indoor farms (n=3) was 11.05 t of CO2e/ha and 0.81kg of CO2e/kg of FPCM. For the outdoor farms (n=2), the average was 5.38 t of CO2e/ha and 1.03kg of CO2e/kg of FPCM. The average for all 5 farms was 8.78 t of CO2e/ha and 0.90kg of CO2e/kg of FPCM. The results showed relatively high variability due to differences in management practices between farms. The 5 farms covered 10% of the total dairy goat farms but may not be representative of an average farm. Methane from enteric fermentation was a major emission source. The use of supplementary feed was highly variable but an important contributor to the carbon footprint. Nitrous oxide can contribute up to 18% of emissions. Indoor goat farming systems produced milk with a significantly higher carbon footprint per area of land farmed compared with outdoor farming systems, although the 2 systems were not significantly different when results were expressed per kilogram of FPCM, at 0.81kg CO2e and 1.03kg CO2e per kg of FPCM, respectively. Both systems had footprints less than other reported dairy goat carbon footprints and on par with those for New Zealand dairy cows. The methodology used to determine enteric methane is important for an accurate and meaningful assessment. The choice of manure management system and supplementary feed can substantially affect the carbon footprint. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Reproducibility of Carbon and Water Cycle by an Ecosystem Process Based Model Using a Weather Generator and Effect of Temporal Concentration of Precipitation on Model Outputs

NASA Astrophysics Data System (ADS)

Miyauchi, T.; Machimura, T.

2014-12-01

GCM is generally used to produce input weather data for the simulation of carbon and water cycle by ecosystem process based models under climate change however its temporal resolution is sometimes incompatible to requirement. A weather generator (WG) is used for temporal downscaling of input weather data for models, where the effect of WG algorithms on reproducibility of ecosystem model outputs must be assessed. In this study simulated carbon and water cycle by Biome-BGC model using weather data measured and generated by CLIMGEN weather generator were compared. The measured weather data (daily precipitation, maximum, minimum air temperature) at a few sites for 30 years was collected from NNDC Online weather data. The generated weather data was produced by CLIMGEN parameterized using the measured weather data. NPP, heterotrophic respiration (HR), NEE and water outflow were simulated by Biome-BGC using measured and generated weather data. In the case of deciduous broad leaf forest in Lushi, Henan Province, China, 30 years average monthly NPP by WG was 10% larger than that by measured weather in the growing season. HR by WG was larger than that by measured weather in all months by 15% in average. NEE by WG was more negative in winter and was close to that by measured weather in summer. These differences in carbon cycle were because the soil water content by WG was larger than that by measured weather. The difference between monthly water outflow by WG and by measured weather was large and variable, and annual outflow by WG was 50% of that by measured weather. The inconsistency in carbon and water cycle by WG and measured weather was suggested be affected by the difference in temporal concentration of precipitation, which was assessed.

Seagrass blue carbon dynamics in the Gulf of Mexico: Stocks, losses from anthropogenic disturbance, and gains through seagrass restoration.

PubMed

Thorhaug, Anitra; Poulos, Helen M; López-Portillo, Jorge; Ku, Timothy C W; Berlyn, Graeme P

2017-12-15

Seagrasses comprise a substantive North American and Caribbean Sea blue carbon sink. Yet fine-scale estimates of seagrass carbon stocks, fluxes from anthropogenic disturbances, and potential gains in sedimentary carbon from seagrass restoration are lacking for most of the Western Hemisphere. To begin to fill this knowledge gap in the subtropics and tropics, we quantified organic carbon (C org ) stocks, losses, and gains from restorations at 8 previously-disturbed seagrass sites around the Gulf of Mexico (GoM) (n=128 cores). Mean natural seagrass C org stocks were 25.7±6.7MgC org ha -1 around the GoM, while mean C org stocks at adjacent barren sites that had previously hosted seagrass were 17.8MgC org ha -1 . Restored seagrass beds contained a mean of 38.7±13.1MgC org ha -1 . Mean C org losses differed by anthropogenic impact type, but averaged 20.98±7.14MgC org ha -1 . C org gains from seagrass restoration averaged 20.96±8.59Mgha -1 . These results, when combined with the similarity between natural and restored C org content, highlight the potential of seagrass restoration for mitigating seagrass C org losses from prior impact events. Our GoM basin-wide estimates of natural C org totaled ~36.4Tg for the 947,327ha for the USA-GoM. Including Mexico, the total basin contained an estimated 37.2-37.5Tg C org . Regional US-GoM losses totaled 21.69Tg C org . C org losses differed significantly among anthropogenic impacts. Yet, seagrass restoration appears to be an important climate change mitigation strategy that could be implemented elsewhere throughout the tropics and subtropics. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessing global carbon burial during Oceanic Anoxic Event 2, Cenomanian-Turonian boundary event

NASA Astrophysics Data System (ADS)

Owens, J. D.; Lyons, T. W.; Lowery, C. M.

2017-12-01

Reconstructing the areal extent and total amount of organic carbon burial during ancient events remains elusive even for the best documented oceanic anoxic event (OAE) in Earth history, the Cenomanian-Turonian boundary event ( 93.9 Ma), or OAE 2. Reports from 150 OAE 2 localities provide a wide global distribution. However, despite the large number of sections, the majority are found within the proto-Atlantic and Tethyan oceans and interior seaways. Considering these gaps in spatial coverage, the pervasive increase in organic carbon (OC) burial during OAE2 that drove carbon isotope values more positive (average of 4‰) can provide additional insight. These isotope data allow us to estimate the total global burial of OC, even for unstudied portions of the global ocean. Thus, we can solve for any `missing' OC sinks by comparing our estimates from a forward carbon-isotope box model with the known, mapped distribution of OC for OAE 2 sediments. Using the known OC distribution and reasonably extrapolating to the surrounding regions of analogous depositional conditions accounts for only 13% of the total seafloor, mostly in marginal marine settings. This small geographic area accounts for more OC burial than the entire modern ocean, but significantly less than the amount necessary to produce the observed isotope record. Using modern and OAE 2 average OC rates we extrapolate further to appropriate depositional settings in the unknown portions of seafloor, mostly deep abyssal plains. This addition significantly increases the predicted amount buried but still does not account for total burial. Additional sources, including hydrocarbon migration, lacustrine, and coal also cannot account for the missing OC. This difference points to unknown portions of the open ocean with high TOC contents or exceptionally high TOC in productive marginal marine regions, which are underestimated in our extrapolations. This difference might be explained by highly productive margins within the Pacific.

Effects of Mid-Level Ethanol Blends on Conventional Vehicle Emissions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knoll, K.; West, B.; Huff, S.

2010-06-01

Tests were conducted in 2008 on 16 late-model conventional vehicles (1999-2007) to determine short-term effects of mid-level ethanol blends on performance and emissions. Vehicle odometer readings ranged from 10,000 to 100,000 miles, and all vehicles conformed to federal emissions requirements for their federal certification level. The LA92 drive cycle, also known as the Unified Cycle, was used for testing because it more accurately represents real-world acceleration rates and speeds than the Federal Test Procedure. Test fuels were splash-blends of up to 20 volume percent ethanol with federal certification gasoline. Both regulated and unregulated air-toxic emissions were measured. For the 16-vehiclemore » fleet, increasing ethanol content resulted in reductions in average composite emissions of both nonmethane hydrocarbons and carbon monoxide and increases in average emissions of ethanol and aldehydes.« less

Ground water in carbonate rocks and regolith in the Fairview area, Tennessee

USGS Publications Warehouse

Burchett, C.R.; Zurawski, Ann; Sparkes, A.K.; Hollyday, E.F.

1983-01-01

Fourteen test wells drilled in the Fairview area, Tennessee, produce from 3 to 100 gallons per minute and have an average yield of 32 gallons per minute, measured while blowing water from the wells with compressed air. In comparison, the average yield of supply wells reported by drillers is 13 gallons per minute. Specific capacities for three of the test wells ranged from 0.3 to 0.6 gallons per minute per foot of drawdown after 8 hours of pumping at 20 to 47 gallons per minute. Two test wells had specific capacities of 1.1 and 0.4 gallons per foot of drawdown after 72 hours of pumping at 55 and 43 gallons per minute. The mineral content of ground water increases greatly below a gypsum horizon approximately 100 feet below the top of the Fort Payne Formation. Ground water above the gypsum horizon, however, meets the standards for finished drinking water. (USGS)

Nitrous oxide emissions from yellow brown soil as affected by incorporation of crop residues with different carbon-to-nitrogen ratios: a case study in central China.

PubMed

Lin, Shan; Iqbal, Javed; Hu, Ronggui; Shaaban, Muhammad; Cai, Jianbo; Chen, Xi

2013-08-01

To investigate the influence of crop residues decomposition on nitrous oxide (N2O) emission, a field study was performed with application of crop residues with different C:N ratios in a bare yellow brown soil at the experimental station of Zhangjiachong at Zigui, China. We set up six experimental treatments: no crop residue (CK), rapeseed cake (RC), potato stalk (PS), rice straw (RS), wheat straw (WS), and corn straw (CS). The carbon (C) to nitrogen (N) ratios of these crop residues were 7.5, 32.9, 40.4, 65.7, and 90.9, respectively. Nitrous oxide fluxes were measured using a static closed chamber method. N2O emissions were significantly enhanced by incorporation of crop residues. Cumulative N2O emissions negatively correlated with C:N ratio (R (2) = 0.9821) of the crop residue, but they were positively correlated with average concentrations of dissolved organic carbon and microbial biomass carbon. Nitrogen emission fraction, calculated as N2O-N emissions originated from the crop residues N, positively correlated with C:N ratio of the residues (P < 0.05). Soil temperature did, whereas soil moisture did not, control the residue's induced N2O emissions because a significant correlation (P < 0.01) existed between soil temperature and N2O emissions in all treatments except the control. In contrast, a significant relationship between soil moisture and N2O emissions was found in the control only. Furthermore, N2O emission significantly correlated (P < 0.05) with NO3 (-)-N, and NH4 (+)-N contents from all residue treatments. These results indicate that (1) crop residues with distinct carbon and nitrogen contents can significantly alter soil N2O flux rates; and (2) soil biotic as well as abiotic variables are critical in determining soil-atmospheric N2O emissions after crop residue incorporation into soil.

[Effects of the frequency and intensity of nitrogen addition on soil pH, the contents of carbon, nitrogen and phosphorus in temperate steppe in Inner Mongolia, China.

PubMed

Zhou, Ji Dong; Shi, Rong Jiu; Zhao, Feng; Han, Si Qin; Zhang, Ying

2016-08-01

A four-year simulated nitrogen (N) deposition experiment involving nine N gradients and two N deposition frequencies (N was added either twice yearly or monthly) was conducted in Inner Mongolian grassland, to examine the effects of frequency and intensity of N addition on pH and the contents of carbon, nitrogen and phosphorus in soil. The results indicated that the soil pH and total phosphorus content, regardless of the N addition frequency, gradually decreased with the increase of N addition intensity. By contrast, the contents of soil available nitrogen and available phosphorus showed an increasing trend, while no significant variation in dissolved organic carbon (DOC) content was observed, and the contents of soil total carbon and total nitrogen had no change. Compared with the monthly N addition, the twice-a-year N addition substantially overestimated the effects of N deposition on decreasing the soil pH and increasing the available phosphorus content, but underestimated the effects of N deposition on increasing the soil available nitrogen content, and the significant difference was found in 0-5 cm soil layer.

Gas-geochemical condition and ecological functions of urban soils in areas with gas generating grounds

NASA Astrophysics Data System (ADS)

Mozharova, Nadezhda; Lebed-Sharlevich, Iana; Kulachkova, Svetlana

2014-05-01

Rapid urbanization and expansion of city borders lead to development of new areas, often following with relief changes, covering of gully-ravine systems and river beds with technogenic grounds containing construction and municipal waste. Decomposition of organic matter in these grounds is a source of methane and carbon dioxide. Intensive generation and accumulation of CO2 and CH4 into grounds may cause a fire and explosion risk for constructed objects. Gases emission to the atmosphere changes the global balance of GHGs and negatively influences on human health. The aim of this investigation is to study gas-geochemical condition and ecological functions of urban soils in areas with gas generating grounds. Studied areas are the gully-ravine systems or river beds, covered with technogenic grounds during land development. Stratigraphic columns of these grounds are 5-17 meters of man-made loamy material with inclusion of construction waste. Gas generating layer with increased content of organic matter, reductive conditions and high methanogenic activity (up to 1.0 ng*g-1*h-1) is situated at the certain depth. Maximum CH4 and CO2 concentrations in this layer reach dangerous values (2-10% and 11%, respectively) in the current standards. In case of disturbance of ground layer (e.g. well-drilling) methane is rapidly transferred by convective flux to atmosphere. The rate of CH4 emission reaches 100 mg*m-2*h-1 resulting in its atmospheric concentration growth by an order of magnitude compared with background. In normal occurrence of grounds methane gradually diffuses into the upper layers by pore space, consuming on different processes (e.g. formation of organic matter, nitrogen compounds or specific particles of magnetite), and emits to atmosphere. CH4 emission rate varies from 1 to 40 mg*m-2*h-1 increasing with depth of grounds. Carbon dioxide emission is about 100 mg*m-2*h-1. During soil formation on gas generating grounds bacterial oxidation of methane, one of the most important ecological functions of such soils, is initiated. Due to high rate of this process (25-30 ng*g-1*h-1) accumulation of methane in the profile does not observed, its content in soil averages 2-5 ppm. Methane emission from soils is low (0.01-0.03 mg*m-2*h-1) or there is a weak consumption of atmospheric CH4, whereby its concentration in the air corresponds to the average content of this gas. Active methane oxidation and decomposition of organic matter under aerobic conditions result to intensive formation of carbon dioxide and, thus, increase its emission (600 mg*m-2*h-1), concentration in soils (0.2-0.9%) and in atmosphere (up to 0.5%). Fixed concentration of CO2 in the air is dangerous for human health. Thus, presence of gas generating grounds with high content of organic matter leads to methane formation, causing its intensive emission to atmosphere. At upper layers of soils and grounds bacterial oxidation of methane occurs and results in complete CH4 utilization. During this process significant amounts of carbon dioxide are released and accumulated in the atmosphere up to concentration dangerous for people. Carbon dioxide emission increases current level of this gas in the urban atmosphere.

Effect of C content on the mechanical properties of solution treated as-cast ASTM F-75 alloys.

PubMed

Herrera, M; Espinoza, A; Méndez, J; Castro, M; López, J; Rendón, J

2005-07-01

The mechanical properties of solution treated ASTM F-75 alloys with various carbon contents have been studied. Alloys cast under the same conditions were subjected to solution treatment for several periods and then their tensile properties were evaluated. In the as-cast conditions, the alloys exhibited higher strength values with increasing carbon content whereas their ductility was not significantly affected. For the solution treated alloys, the variation of the strength was characterized by a progressive increase for short treatment times until a maximum value was achieved, which was followed by a diminution in this property for longer treatment times. This behavior was more accentuated for the case of the alloys with medium carbon contents, which also exhibited the highest values of strength. Furthermore, the alloy's ductility was enhanced progressively with increasing solution treatment time. This improvement in ductility was significantly higher for the medium carbon alloys compared with the rest of the studied alloys. Thus, high and low carbon contents in solution treated ASTM F-75 alloys did not produced sufficiently high tensile properties.

Geochemical characteristics of organic matter in the Andaman Sea sediments: Implications for source, paleovegetation and paleoclimate changes

NASA Astrophysics Data System (ADS)

Hossain, H. M. Z.; Sampei, Y.; Kawahata, H.

2016-12-01

The distribution, source, and redox variation of sedimentary organic matter in the Andaman Sea is significant for understanding its biogeochemical cycle, which we determined the total organic carbon (TOC), total nitrogen (TN), and n-alkanes contents. TOC and TN concentrations varied from 0.61 to 1.18 wt.% (average 0.87 wt.%) and 0.07 to 0.17 wt.% (average 0.13 wt.%), respectively with high TOC in the clay-rich sediments indicate hydrodynamic sorting readily controlled TOC abundances. Bulk C/N ratio (5.51 to 11.92, average 7.89) is attributed to the high inputs of organic matter from planktonic sources and an appreciable amounts of terrestrial derived organic matter. n-Alkane distributions from the Andaman Sea sediment cores are characterized mainly by C17 to C35, with odd-over-even predominance suggest a diverse origin of organic matter. High relative abundances of mid-chain n-alkanes of C23 and C25 recorded in the samples that are characteristically derived from submerges/floating aquatic macrophytes. However, odd long-chain n-alkanes from C27 to C33 with high peaks at C29 and C31 were detected in the samples reflecting a terrigenous origin of organic matter. The average chain length (ACL), carbon preference index (CPI), Paq and Pwax ratio values further suggested that major influence of organic matter from non-emergent aquatic macrophytes together significant proportions of grasses and herbs. Low Pr/Ph and Tm/Ts ratios in most section implying a more reducing to suboxic conditions prevailed during organic matter preservation in the oceanic event. However, high ACL values and low Paq values in the down-core variation could suggest initially cold and dry climates and gradually shifted to warm and humid conditions.

Investigating organic matter in Fanno Creek, Oregon, Part 2 of 3: sources, sinks, and transport of organic matter with fine sediment

USGS Publications Warehouse

Keith, Mackenzie K.; Sobieszczyk, Steven; Goldman, Jami H.; Rounds, Stewart A.

2014-01-01

Organic matter (OM) is abundant in Fanno Creek, Oregon, USA, and has been tied to a variety of water-quality concerns, including periods of low dissolved oxygen downstream in the Tualatin River, Oregon. The key sources of OM in Fanno Creek and other Tualatin River tributaries have not been fully identified, although isotopic analyses from previous studies indicated a predominantly terrestrial source. This study investigates the role of fine sediment erosion and deposition (mechanisms and spatial patterns) in relation to OM transport. Geomorphic mapping within the Fanno Creek floodplain shows that a large portion (approximately 70%) of the banks are eroding or subject to erosion, likely as a result of the imbalance caused by anthropogenic alteration. Field measurements of long- and short-term bank erosion average 4.2 cm/year and average measurements of deposition for the watershed are 4.8 cm/year. The balance between average annual erosion and deposition indicates an export of 3,250 metric tons (tonnes, t) of fine sediment to the Tualatin River—about twice the average annual export of 1,880 t of sediment at a location 2.4 km from the creek’s mouth calculated from suspended sediment load regressions from continuous turbidity data and suspended sediment samples. Carbon content from field samples of bank material, combined with fine sediment export rates, indicates that about 29–67 t of carbon, or about 49–116 t of OM, from bank sediment may be exported to the Tualatin River from Fanno Creek annually, an estimate that is a lower bound because it does not account for the mass wasting of organic-rich O and A soil horizons that enter the stream.

Investigating organic matter in Fanno Creek, Oregon, Part 2 of 3: Sources, sinks, and transport of organic matter with fine sediment

NASA Astrophysics Data System (ADS)

Keith, Mackenzie K.; Sobieszczyk, Steven; Goldman, Jami H.; Rounds, Stewart A.

2014-11-01

Organic matter (OM) is abundant in Fanno Creek, Oregon, USA, and has been tied to a variety of water-quality concerns, including periods of low dissolved oxygen downstream in the Tualatin River, Oregon. The key sources of OM in Fanno Creek and other Tualatin River tributaries have not been fully identified, although isotopic analyses from previous studies indicated a predominantly terrestrial source. This study investigates the role of fine sediment erosion and deposition (mechanisms and spatial patterns) in relation to OM transport. Geomorphic mapping within the Fanno Creek floodplain shows that a large portion (approximately 70%) of the banks are eroding or subject to erosion, likely as a result of the imbalance caused by anthropogenic alteration. Field measurements of long- and short-term bank erosion average 4.2 cm/year and average measurements of deposition for the watershed are 4.8 cm/year. The balance between average annual erosion and deposition indicates an export of 3,250 metric tons (tonnes, t) of fine sediment to the Tualatin River-about twice the average annual export of 1,880 t of sediment at a location 2.4 km from the creek's mouth calculated from suspended sediment load regressions from continuous turbidity data and suspended sediment samples. Carbon content from field samples of bank material, combined with fine sediment export rates, indicates that about 29-67 t of carbon, or about 49-116 t of OM, from bank sediment may be exported to the Tualatin River from Fanno Creek annually, an estimate that is a lower bound because it does not account for the mass wasting of organic-rich O and A soil horizons that enter the stream.

Horizon-Specific Bacterial Community Composition of German Grassland Soils, as Revealed by Pyrosequencing-Based Analysis of 16S rRNA Genes ▿ †

PubMed Central

Will, Christiane; Thürmer, Andrea; Wollherr, Antje; Nacke, Heiko; Herold, Nadine; Schrumpf, Marion; Gutknecht, Jessica; Wubet, Tesfaye; Buscot, François; Daniel, Rolf

2010-01-01

The diversity of bacteria in soil is enormous, and soil bacterial communities can vary greatly in structure. Here, we employed a pyrosequencing-based analysis of the V2-V3 16S rRNA gene region to characterize the overall and horizon-specific (A and B horizons) bacterial community compositions in nine grassland soils, which covered three different land use types. The entire data set comprised 752,838 sequences, 600,544 of which could be classified below the domain level. The average number of sequences per horizon was 41,824. The dominant taxonomic groups present in all samples and horizons were the Acidobacteria, Betaproteobacteria, Actinobacteria, Gammaproteobacteria, Alphaproteobacteria, Deltaproteobacteria, Chloroflexi, Firmicutes, and Bacteroidetes. Despite these overarching dominant taxa, the abundance, diversity, and composition of bacterial communities were horizon specific. In almost all cases, the estimated bacterial diversity (H′) was higher in the A horizons than in the corresponding B horizons. In addition, the H′ was positively correlated with the organic carbon content, the total nitrogen content, and the C-to-N ratio, which decreased with soil depth. It appeared that lower land use intensity results in higher bacterial diversity. The majority of sequences affiliated with the Actinobacteria, Bacteroidetes, Cyanobacteria, Fibrobacteres, Firmicutes, Spirochaetes, Verrucomicrobia, Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria were derived from A horizons, whereas the majority of the sequences related to Acidobacteria, Chloroflexi, Gemmatimonadetes, Nitrospira, TM7, and WS3 originated from B horizons. The distribution of some bacterial phylogenetic groups and subgroups in the different horizons correlated with soil properties such as organic carbon content, total nitrogen content, or microbial biomass. PMID:20729324

Total Contents and Sequential Extraction of Heavy Metals in Soils Irrigated with Wastewater, Akaki, Ethiopia

NASA Astrophysics Data System (ADS)

Fitamo, Daniel; Itana, Fisseha; Olsson, Mats

2007-02-01

The Akaki River, laden with untreated wastes from domestic, industrial, and commercial sources, serves as a source of water for irrigating vegetable farms. The purpose of this study is to identify the impact of waste-water irrigation on the level of heavy metals and to predict their potential mobility and bioavailability. Zn and V had the highest, whereas Hg the lowest, concentrations observed in the soils. The average contents of As, Co, Cr, Cu, Ni, Zn, V, and Hg of both soils; and Pb and Se from Fluvisol surpassed the mean + 2 SD of the corresponding levels reported for their uncontaminated counterparts. Apparently, irrigation with waste water for the last few decades has contributed to the observed higher concentrations of the above elements in the study soils (Vertisol and Fluvisol) when compared to uncontaminated Vertisol and Fluvisol. On the other hand, Vertisol accommodated comparatively higher average levels of Cr, Cu, Ni, Zn, etc V, and Cd, whereas high contents of Pb and Se were observed in Fluvisol. Alternatively, comparable levels of Co and Hg were found in either soil. Except for Ni, Cr, and Cd in contaminated Vertisol, heavy metals in the soils were not significantly affected by the depth (0-20 and 30-50 cm). When the same element from the two soils was compared, the levels of Cr, Cu, Ni, Pb, Se, Zn, V, Cd at 0-20 cm; and Cr, Ni, Cu, Cd, and Zn at 30-50 cm were significantly different. Organic carbon (in both soils), CEC (Fluvisol), and clay (Vertisol) exhibited significant positive correspondences with the total heavy metal levels. Conversely, Se and Hg contents revealed perceptible associations with carbonate and pH. The exchangeable fraction was dominated by Hg and Cd, whereas the carbonate fraction was abounded with Cd, Pb, and Co. conversely, V and Pb displayed strong affinity to reducible fraction, where as Cr, Cu, Zn, and Ni dominated the oxidizable fraction. Cr, Hg, Se, and Zn (in both soils) showed preference to the residual fraction. Generally, a considerable proportion of the total levels of many of the heavy metals resided in non residual fractions. The enhanced lability is generally expected to follow the order: Cd > Co > Pb > Cu > Ni > Se > V and Pb > Cd > Co > Cu > Ni > Zn in Vertisol and Fluvisol, respectively. For the similar wastewater application, the soil variables influence the status and the distribution of the associated heavy metals among the different soil fractions in the study soils. Among heavy metals that presented relatively elevated levels and with potential mobility, Co, Cu, Ni (either soil), V (Vertisol), Pb, and Zn (Fluvisol) could pose health threat through their introduction into the food chain in the wastewater irrigated soils.

Ash Tree Leaf Litter (Fraxinus excelsior L.) Breakdown in Two Different Biotopes and Streams

NASA Astrophysics Data System (ADS)

Fleituch, Tadeusz; Leichtfried, Maria

2004-11-01

Coarse (0.5 mm) and fine (0.1 mm) mesh size bag methodology was used for comparing the breakdown of ash tree leaves (Fraxinus excelsior L.) in two biotopes (dry - terrestrial and wet - overflown stream zones) in two low order streams (the Oberer Seebach (OSB), Lower Austria and the Brzezowka stream (BRZ), Beskidy Mountains, southern Poland). In total, 96 bags were exposed in autumn 2000. Ash-free dry mass (AFDM) ranged in dry zones of both streams from 94-62% (OSB) and 85-53% (BRZ) respectively. The decomposition process was faster in wet zones: 96-33% (OSB) and 56-11% (B) during the study period. Significant differences in ash breakdown and its chemical content between studied streams were found. Total organic carbon (TOC) and total nitrogen content (TN) of AFDM of litter showed increased differences with experiment duration between zones and between two bag types for both streams. The strongest increase of TOC and TN content (100% on average initial content) for bag types, zones, and streams was observed in the first two weeks of the experiment. These results confirm the importance of chemical compounds for microbiological processes (biofilms) in different ecosystem biotopes. (

Options for legal measures to reduce acrylamide contents in the most relevant foods.

PubMed

Grob, K

2007-01-01

Options of taking measures for reducing acrylamide exposure are discussed from the viewpoint of health authorities. To achieve a significant effect on total exposure (without changing eating habits), a substantial reduction must be accomplished for the foods contributing most to total intake. Priority should be given to consumers with high exposure, which means that the average intake profile is not relevant, but high consumption of products with high acrylamide contents is relevant. Rather than introducing legal limits on acrylamide in the end-products, more basic factors determining acrylamide formation should be brought under control. Five measures are proposed. (1) For the preparation of fried and roasted products, potatoes low in reducing sugars should be made available to households and commercial outlets. (2) The content of reducing sugars in prefabricates for French fries should be limited. (3) Newly installed fryers should control the temperature profile from an initially high to a lower final value. (4) The use of ammonium carbonate in bakery products should be restricted. (5) There should be provisions to intervene if an acrylamide content clearly exceeds the level determined by good manufacturing practice and the products involved substantially contribute to total exposure in cases of high consumption.

Soil total carbon content, aggregation, bulk density, and penetration resistance of croplands and nearby grasslands

USDA-ARS?s Scientific Manuscript database

Converting native grassland (NGL) to cropland (CL) decreases soil organic matter contents (components of soil total carbon contents, STCCs), which often leads to soil degradation. Reestablishing grass on CL generally increases soil organic matter, which improves soil conditions. This study was condu...

40 CFR 98.286 - Data reporting requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... petroleum coke consumed). (7) Sampling analysis results for carbon content of consumed petroleum coke as... content factor of petroleum coke from the supplier or as measured by the applicable method in § 98.284(c) for each month (percent by weight expressed as a decimal fraction). (5) Whether carbon content of the...

Baseline-dependent responses of soil organic carbon dynamics to climate and land disturbances

USGS Publications Warehouse

Tan, Zhengxi; Liu, Shuguang

2013-01-01

Terrestrial carbon (C) sequestration through optimizing land use and management is widely considered a realistic option to mitigate the global greenhouse effect. But how the responses of individual ecosystems to changes in land use and management are related to baseline soil organic C (SOC) levels still needs to be evaluated at various scales. In this study, we modeled SOC dynamics within both natural and managed ecosystems in North Dakota of the United States and found that the average SOC stock in the top 20 cm depth of soil lost at a rate of 450 kg C ha−1 yr−1 in cropland and 110 kg C ha−1 yr−1 in grassland between 1971 and 1998. Since 1998, the study area had become a SOC sink at a rate of 44 kg C ha−1 yr−1. The annual rate of SOC change in all types of lands substantially depends on the magnitude of initial SOC contents, but such dependency varies more with climatic variables within natural ecosystems and with management practices within managed ecosystems. Additionally, soils with high baseline SOC stocks tend to be C sources following any land surface disturbances, whereas soils having low baseline C contents likely become C sinks following conservation management.

Reburning Characteristics of Residual Carbon in Fly Ash from CFB Boilers

NASA Astrophysics Data System (ADS)

Zhang, S. H.; Luo, H. H.; Chen, H. P.; Yang, H. P.; Wang, X. H.

The content of residual carbon in fly ash of CFB boilers is a litter high especially when low-grade coal, such as lean coal, anthracite coal, gangue, etc. is in service, which greatly influences the efficiency of boilers and fly ash further disposal. Reburn of fly ash through collection, recirculation in CFB furnace or external combustor is a possibly effective strategy to decrease the carbon content, mainly depending on the residual carbon reactivity. In this work, the combustion properties of residual carbon in fly ash and corresponding original coal from large commercial CFB boilers (Kaifeng (440t/h), and Fenyi (410t/h), all in china) are comparably investigated through experiments. The residual carbon involved was firstly extracted and enriched from fly ash by means of floating elutriation to mitigate the influence of ash and minerals on the combustion behavior of residual carbon. Then, the combustion characteristic of two residual carbons and the original coal particles was analyzed with thermogravimetric analyzer (TGA, STA409C from Nestch, Germany). It was observed that the ignition temperature of the residual carbon is much higher than that of original coal sample, and the combustion reactivity of residual carbon is not only dependent on the original coal property, but also the operating conditions. The influence of oxygen content and heating rate was also studied in TGA. The O2 concentration is set as 20%, 30%, 40% and 70% respectively in O2/N2 gas mixture with the flow rate of 100ml/min. It was found that higher oxygen content is favor for decreasing ignition temperature, accelerating the combustion rate of residual carbon. And about 40% of oxygen concentration is experimentally suggested as an optimal value when oxygen-enriched combustion is put into practice for decreasing residual carbon content of fly ash in CFB boilers.

Carbon cycling in high-latitude ecosystems

NASA Technical Reports Server (NTRS)

Townsend, Alan; Frolking, Stephen; Holland, Elizabeth

1992-01-01

The carbon-rich soils and peatlands of high-latitude ecosystems could substantially influence atmospheric concentrations of CO2 and CH4 in a changing climate. Currently, cold, often waterlogged conditions retard decomposition, and release of carbon back to the atmosphere may be further slowed by physical protection of organic matter in permafrost. As a result, many northern ecosystems accumulate carbon over time (Billings et al., 1982; Poole and Miller, 1982), and although such rates of accumulation are low, thousands of years of development have left Arctic ecosystems with an extremely high soil carbon content; Schlesinger's (1984) average value of 20.4 kg C/m(sup 2) leads to a global estimate of 163 x 10(exp 15) g C. All GCM simulations of a doubled CO2 climate predict the greatest warming to occur in the polar regions (Dickinson, 1986; Mitchell, 1989). Given the extensive northern carbon pools and the strong sensitivity of decomposition processes to temperature, even a slight warming of the soil could dramatically alter the carbon balance of Arctic ecosystems. If warming accelerates rates of decomposition more than rates of primary production, a sizeable additional accumulation of CO2 in the atmosphere could occur. Furthermore, CH4 produced in anaerobic soils and peatlands of the Arctic already composes a good percentage of the global efflux (Cicerone and Oremlund, 1988); if northern soils become warmer and wetter as a whole, CH4 emissions could dramatically rise. A robust understanding of the primary controls of carbon fluxes in Arctic ecosystems is critical. As a framework for a systematic examination of these controls, we discussed a conceptual model of regional-scale Arctic carbon turnover, including CH4 production, and based upon the Century soil organic matter model.

Digestion of high rate activated sludge coupled to biochar formation for soil improvement in the tropics.

PubMed

Nansubuga, Irene; Banadda, Noble; Ronsse, Frederik; Verstraete, Willy; Rabaey, Korneel

2015-09-15

High rate activated sludge (HRAS) is well-biodegradable sludge enabling energy neutrality of wastewater treatment plants via anaerobic digestion. However, even through successful digestion a notable residue still remains. Here we investigated whether this residue can be converted to biochar, for its use as a fertilizer or as a solid fuel, and assessed its characteristics and overall process efficiency. In a first phase, HRAS was anaerobicaly digested under mesophilic conditions at a sludge retention time of 20 days. HRAS digested well (57.9 ± 6.2% VS degradation) producing on average 0.23 ± 0.04 L CH4 per gram VS fed. The digestate particulates were partially air-dried to mimic conditions used in developing countries, and subsequently converted to biochar by fixed-bed slow pyrolysis at a residence time of 15 min and at highest heating temperatures (HHT) of 300 °C, 400 °C and 600 °C. Subsequently, the produced chars were characterized by proximate analysis, CHN-elemental analysis, pH in solution and bomb calorimetry for higher heating value. The yield and volatile matter decreased with increasing HHT while ash content and fixed carbon increased with increasing HHT. The produced biochar showed properties optimal towards soil amendment when produced at a temperature of 600 °C with values of 5.91 wt%, 23.75 wt%, 70.35% on dry basis (db) and 0.44 for volatile matter, fixed carbon, ash content and H/C ratio, respectively. With regard to its use for energy purposes, the biochar represented a lower calorific value than the dried HRAS digestate likely due to high ash content. Based on these findings, it can be concluded that anaerobic digestion of HRAS and its subsequent biochar formation at HHT of 600 °C represents an attractive route for sludge management in tropic settings like in Uganda, coupling carbon capture to energy generation, carbon sequestration and nutrient recovery. Copyright © 2015 Elsevier Ltd. All rights reserved.

40 CFR 62.15330 - What must I include in the initial report?

Code of Federal Regulations, 2014 CFR

2014-07-01

... emissions. (3) The 4-hour block or 24-hour daily arithmetic average concentration of carbon monoxide... specifications in appendix B of 40 CFR part 60 in conducting the evaluation. (e) The maximum demonstrated load of... combustion unit uses activated carbon to control dioxins/furans or mercury emissions, the average carbon feed...

40 CFR 62.15305 - What records must I keep for continuously monitored pollutants or parameters?

Code of Federal Regulations, 2014 CFR

2014-07-01

... oxides emissions. (4) All 1-hour average concentrations of carbon monoxide emissions. (5) All 1-hour... carbon monoxide emissions. (4) All 4-hour block arithmetic average load levels of your municipal waste... combustion units only, nitrogen oxides emissions. (iii) Carbon monoxide emissions. (iv) Load levels of your...

An initial examination of carbonate variability in the western equatorial Pacific: XRF results from the lower to middle Miocene of IODP Site U1490

NASA Astrophysics Data System (ADS)

Valerio, D. A.; Kulhanek, D. K.; Rosenthal, Y.; Holbourn, A. E.

2017-12-01

International Ocean Discovery Program (IODP) Expedition 363 sought to determine the nature of and driving forces behind climate variability in the Western Pacific Warm Pool (WPWP) region throughout the Neogene on millennial, orbital, and geologic timescales. Our research focuses on the Miocene (19-9 Ma) sediment record from IODP Site U1490 to examine changes in carbonate production and burial in the WPWP as a record of variations in the regional/global carbon cycle. This interval is of particular interest because it spans the Middle Miocene Climatic Optimum, the Middle Miocene Climate Transition, and the late Miocene carbonate crash. Site U1490 is located on the northern edge of Eauripik Rise at 05°58.95'N, 142°39.27'E in the northern part of the WPWP. At 2341 m water depth, today the site is bathed in Upper Circumpolar Deepwater. Miocene sediment at Site U1490 primarily consists of clay-bearing to clay-rich foraminifer-rich nannofossil ooze, although biogenic silica (primarily radiolaria) is a significant component in the lowermost part of the record. The sedimentation rate in the early to middle Miocene was very low (<1 cm/kyr), increasing to 1.6 cm/kyr in the late Miocene. Initial shipboard results show an average calcium carbonate content of 87 wt% throughout the site, with the most significant variations in the lower to middle Miocene, where contents range from 20 to 85 wt%. We collected X-ray fluorescence (XRF) data at 1 cm resolution along the composite stratigraphic section over the 19-9 Ma interval to obtain a qualitative measure of the bulk chemistry of the sediment. We will use the weight percent calcium carbonate of discrete samples to calibrate the XRF data to generate a high-resolution carbonate record. We observe cyclical variations in the Ca/Ba, which may reflect variations in productivity and/or dissolution through this interval, although additional work is needed to fully interpret these data. Ultimately our research will allow for comparison between records obtained from these cores located in the western equatorial Pacific to those obtained in the eastern and central Pacific, which will better elucidate the nature of the carbon system during the Miocene.

Organic carbon storage and benthic consumption in sediments of northern fjords (60-80°N)

NASA Astrophysics Data System (ADS)

Włodarska-Kowalczuk, Maria; Zaborska, Agata; Jankowska, Emilia; Mazurkiewicz, Mikołaj

2017-04-01

Fjords have been recently recognized as hotspots of organic carbon storage, with organic carbon burial rates one hundred times larger than the global ocean average, accounting for 11% of global annual marine carbon burial (Smith et al. (2015) Nature Geoscience 8: 450-453). The organic carbon production and processing in coastal waters and sediments are controlled by environmental settings that are likely to be reshaped in the course of the global warming. The fastest and strongest changes are to occur in polar regions. In the present study we compare organic carbon stocks, accumulation and burial in temperate (Raunefjorden, Ullsfjorden, Balsfjorden) and Arctic (Hornsund, Kongsfjorden, Rijpfjorden) fjords located along the latitudinal/thermal gradient from the southern Norway (60 °N) to North of Svalbard (80 °N). The sediment cores were collected at 3 to 5 stations within the central basin at 150-300 m in each fjord during r/v Helmer Hansen and r/v Oceania cruises in 2014 and 2015. Vertical patterns of grain size and organic matter content and sources (Corg concentration, stable isotope δ13C signature, photosynthetic pigments concentration) have been analyzed. Sediment accumulation rates have been estimated with use of 210Pb dating method. Fresh carbon accumulation rate was estimated based on organic carbon concentration is surface sediments and mass sediment accumulation rate. The variability in metazoan productivity and carbon consumption (calculated based on the macro- and meiobenthic species biomass spectra in samples collected at the same stations) was also assessed to explore the patterns of biological controls of carbon storage in sediments. Carbon burial was estimated by multiplying organic carbon concentration in deepest sampled sediments and mass sediment accumulation rate. The effects of contrasting hydrological regimes and biological activity on the carbon storage in the studied fjords are discussed from the perspective of possible effects of climate warming driven changes on the Arctic fjordic sedimentary systems.

Critical carbon input to maintain current soil organic carbon stocks in global wheat systems

PubMed Central

Wang, Guocheng; Luo, Zhongkui; Han, Pengfei; Chen, Huansheng; Xu, Jingjing

2016-01-01

Soil organic carbon (SOC) dynamics in croplands is a crucial component of global carbon (C) cycle. Depending on local environmental conditions and management practices, typical C input is generally required to reduce or reverse C loss in agricultural soils. No studies have quantified the critical C input for maintaining SOC at global scale with high resolution. Such information will provide a baseline map for assessing soil C dynamics under potential changes in management practices and climate, and thus enable development of management strategies to reduce C footprint from farm to regional scales. We used the soil C model RothC to simulate the critical C input rates needed to maintain existing soil C level at 0.1° × 0.1° resolution in global wheat systems. On average, the critical C input was estimated to be 2.0 Mg C ha−1 yr−1, with large spatial variability depending on local soil and climatic conditions. Higher C inputs are required in wheat system of central United States and western Europe, mainly due to the higher current soil C stocks present in these regions. The critical C input could be effectively estimated using a summary model driven by current SOC level, mean annual temperature, precipitation, and soil clay content. PMID:26759192

Adsorption of steroid micropollutants on polymer-based spherical activated carbon (PBSAC).

PubMed

Tagliavini, Matteo; Engel, Fabio; Weidler, Peter Georg; Scherer, Torsten; Schäfer, Andrea Iris

2017-09-05

Removal and interaction mechanisms of four different steroid micropollutants, estrone (E1), estradiol (E2), progesterone (P) and testosterone (T) were determined for different types of polymer-based spherical activated carbon (PBSAC). Higher than 90% removal and significantly faster kinetics compared to conventional granular activated carbon (GAC) were observed, while performance was comparable with powdered activated carbon (PAC). No influence of pH in the range 2-12 was determined, while the presence of humic acid (HA) reduced both the removal and the kinetic by up to 20%. PBSAC was characterized in terms of morphology and material properties. The low oxygen content was identified as the main cause for the high performance observed. This was attributed to the enhancement of the hydrophobic effect between PBSAC and hormones and the reduced interactions between PBSAC and water. The ratio of micropollutant size (∼0.8nm) and average pore size (1-2nm) proved ideal for both micropollutant adsorption and HA exclusion. The homogenous size, spherical shape and surface smoothness of PBSAC did not influence adsorption negatively and make PBSAC a very promising sorbent for a vast range of applications, in particular for the removal of micropollutants in water treatment applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantified carbon input for maintaining existing soil organic carbon stocks in global wheat systems

NASA Astrophysics Data System (ADS)

Wang, G.

2017-12-01

Soil organic carbon (SOC) dynamics in croplands is a crucial component of global carbon (C) cycle. Depending on local environmental conditions and management practices, typical C input is generally required to reduce or reverse C loss in agricultural soils. No studies have quantified the critical C input for maintaining SOC at global scale with high resolution. Such information will provide a baseline map for assessing soil C dynamics under potential changes in management practices and climate, and thus enable development of management strategies to reduce C footprint from farm to regional scales. We used the soil C model RothC to simulate the critical C input rates needed to maintain existing soil C level at 0.1°× 0.1° resolution in global wheat systems. On average, the critical C input was estimated to be 2.0 Mg C ha-1 yr-1, with large spatial variability depending on local soil and climatic conditions. Higher C inputs are required in wheat system of central United States and western Europe, mainly due to the higher current soil C stocks present in these regions. The critical C input could be effectively estimated using a summary model driven by current SOC level, mean annual temperature, precipitation, and soil clay content.

Changes in soil microbial functional diversity and biochemical characteristics of tree peony with amendment of sewage sludge compost.

PubMed

Huang, Xiangdong; Xue, Dong; Xue, Lian

2015-08-01

A greenhouse experiment was conducted to investigate the impact of sewage sludge compost application on functional diversity of soil microbial communities, based on carbon source utilization, and biochemical characteristics of tree peony (Paeonia suffruticosa). Functional diversity was estimated with incubations in Biolog EcoPlates and well color development was used as the functional trait for carbon source utilization. The average well color development and Shannon index based on the carbon source utilization pattern in Biolog EcoPlates significantly increased with the increasing sludge compost application in the range of 0-45%, with a decreasing trend above 45%. Principal component analysis of carbon source utilization pattern showed that sludge compost application stimulated the utilization rate of D-cellobiose and α-D-lactose, while the utilization rate of β-methyl-D-glucoside, L-asparagine, L-serine, α-cyclodextrin, γ-hydroxybutyric acid, and itaconic acid gradually increased up to a sludge compost amendment dosage of 45% and then decreased above 45%. The chlorophyll content, antioxidase (superoxide dismutase, catalase, and peroxidase) activities, plant height, flower diameter, and flower numbers per plant of tree peony increased significantly with sludge compost dosage, reaching a peak value at 45 %, and then decreased with the exception that activity of superoxide dismutase and catalase did not vary significantly.

Fluorescently tuned nitrogen-doped carbon dots from carbon source with different content of carboxyl groups

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Hao; Wang, Yun; Dai, Xiao

2015-08-01

In this study, fluorescent nitrogen-doped carbon dots (NCDs) were tuned via varying the sources with different number of carboxyl groups. Owing to the interaction between amino and carboxyl, more amino groups conjugate the surface of the NCDs by the source with more carboxyl groups. Fluorescent NCDs were tuned via varying the sources with different content of carboxyl groups. Correspondingly, the nitrogen content, fluorescence quantum yields and lifetime of NCDs increases with the content of carboxyl groups from the source. Furthermore, cytotoxicity assay and cell imaging test indicate that the resultant NCDs possess low cytotoxicity and excellent biocompatibility.

Soil color indicates carbon and wetlands: developing a color-proxy for soil organic carbon and wetland boundaries on sandy coastal plains in South Africa.

PubMed

Pretorius, M L; Van Huyssteen, C W; Brown, L R

2017-10-13

A relationship between soil organic carbon and soil color is acknowledged-albeit not a direct one. Since heightened carbon contents can be an indicator of wetlands, a quantifiable relationship between color and carbon might assist in determining wetland boundaries by rapid, field-based appraisal. The overarching aim of this initial study was to determine the potential of top soil color to indicate soil organic carbon, and by extension wetland boundaries, on a sandy coastal plain in South Africa. Data were collected from four wetland types in northern KwaZulu-Natal in South Africa. Soil samples were taken to a depth of 300 mm in three transects in each wetland type and analyzed for soil organic carbon. The matrix color was described using a Munsell soil color chart. Various color indices were correlated with soil organic carbon. The relationship between color and carbon were further elucidated using segmented quantile regression. This showed that potentially maximal carbon contents will occur at values of low color indices, and predictably minimal carbon contents will occur at values of low or high color indices. Threshold values can thus be used to make deductions such as "when the sum of dry and wet Value and Chroma values is 9 or more, carbon content will be 4.79% and less." These threshold values can then be used to differentiate between wetland and non-wetland sites with a 70 to 100% certainty. This study successfully developed a quantifiable correlation between color and carbon and showed that wetland boundaries can be determined based thereon.

Slope stability improvement using low intensity field electrosmosis

NASA Astrophysics Data System (ADS)

Armillotta, Pasquale

2014-05-01

The electrosmosis technique has been introduced in the past for slope stabilization. However, its application to real cases has been scarce due to several drawbacks mostly related to the high intensity electric field needed (1.0 V/cm or higher): the rapid degradation of the electrodes, the high system management cost, the heating and cracking of the soil and the reduction of its colloidal fraction. Thanks to the introduction of new materials, the technique is currently applied to decrease the consolidation time of saturated clay soils (forcing the elimination of water), consequently improving its mechanical strength. In clay soils, the volume variation is influenced by the presence of smectites. The clay compressibility decreases with the increasing of electrolytes concentration. Soil containing smectites that have interacted with calcium showed a reduction or the absence of swelling during hydration with distilled water and a positive increase of their shear strength. The different values of pH between the anode (acid) and the cathode (basic), induced by the electrosmosis create the conditions for the precipitation of CaCO3 near the cathode. The injection of solutions containing calcium in soils and their diffusion induced by the electrosmosis, lead to calcium precipitation and consequential increase of the shear strength. The material technological advances and the laboratory experiences described in this paper, demonstrate that the use low electric field (0.1 V/cm or lower) intensity electrosmosis (LEFE in acronym) can be effective for soil dewatering and shear strength increase while reducing its adverse effect. The LEFE can be used to: reduce the potential for swelling of active clay minerals through the introduction of ions and the precipitation of hardening substances; induce the "dewatering" in cohesive soils. Several Lab activities were carried out, using custom made electrosmosis equipment. These activities can be divided in two phases: Phase 1: Carbonates were mixed to a natural soil obtaining three groups of soil samples at different carbonates level; the geotechnical characterization of each group was carried out; Phase 2: LEFE was applied to induce the precipitation of CaCO3, the reduction of the swelling potential of clay minerals and the increment of the soil shear strength. The outcomes of Phase 1 indicated that: the values of specific gravity of the grains, plasticity index (PI) and Value of Blue (VB) decrease with the increase carbonate content; the shear strength increases with the carbonates content. From the second laboratory phase, we observed: an almost constant pH values within the sample; an increment of the carbonate content after LEFE treatment regardless of its duration; this increment is particularly significant after 60 days of treatment; a reduction of the swelling potential of soil; that the water content at the end of each treatment, regardless of its duration and intensity of the electric field, shows similar values; that the values of the soil shear strength (after 60 days of LEFE treatment) are always greater than those of the natural soil (average +7%). During the LEFE treatment, the pore fluid used is water taken from the local groundwater, with pH = 7.3 and hardness of 34.6 ° F. The CaCO3 content in treated samples increases with the duration of treatment. The application of LEFE appears to be effective in increasing the carbonate content and improve mechanical strenght of the soil; further development of the research will apply the LEFE to an ideal slope model and to a real case.

Petroleum pollution in surface sediments of Daya Bay, South China, revealed by chemical fingerprinting of aliphatic and alicyclic hydrocarbons

NASA Astrophysics Data System (ADS)

Gao, Xuelu; Chen, Shaoyong

2008-10-01

Nine surface sediments collected from Daya Bay have been Soxhlet-extracted with 2:1 (v/v) dichloromethane-methanol. The non-aromatic hydrocarbon (NAH) fraction of solvent extractable organic matter (EOM) and some bulk geochemical parameters have been analyzed to determine petroleum pollution of the bay. The NAH content varies from 32 to 276 μg g -1 (average 104 μg g -1) dry sediment and accounts for 5.8-64.1% (average 41.6%) of the EOM. n-Alkanes with carbon number ranging from 15 to 35 are identified to be derived from both biogenic and petrogenic sources in varying proportions. The contribution of marine authigenic input to the sedimentary n-alkanes is lower than the allochthonous input based on the average n-C 31/ n-C 19 alkane ratio. 25.6-46.5% of the n-alkanes, with a mean of 35.6%, are contributed by vascular plant wax. Results of unresolved complex mixture, isoprenoid hydrocarbons, hopanes and steranes also suggest possible petroleum contamination. There is strong evidence of a common petroleum contamination source in the bay.

Investigating Rare Earth Element Systematics in the Marcellus Shale

NASA Astrophysics Data System (ADS)

Yang, J.; Torres, M. E.; Kim, J. H.; Verba, C.

2014-12-01

The lanthanide series of elements (the 14 rare earth elements, REEs) have similar chemical properties and respond to different chemical and physical processes in the natural environment by developing unique patterns in their concentration distribution when normalized to an average shale REE content. The interpretation of the REE content in a gas-bearing black shale deposited in a marine environment must therefore take into account the paleoredox conditions of deposition as well as any diagenetic remobilization and authigenic mineral formation. We analyzed 15 samples from a core of the Marcellus Shale (Whipkey ST1, Greene Co., PA) for REEs, TOC, gas-producing potential, trace metal content, and carbon isotopes of organic matter in order to determine the REE systematics of a black shale currently undergoing shale gas development. We also conducted a series of sequential leaching experiments targeting the phosphatic fractions in order to evaluate the dominant host phase of REEs in a black shale. Knowledge of the REE system in the Marcellus black shale will allow us to evaluate potential REE release and behavior during hydraulic fracturing operations. Total REE content of the Whipkey ST1 core ranged from 65-185 μg/g and we observed three distinct REE shale-normalized patterns: middle-REE enrichment (MREE/MREE* ~2) with heavy-REE enrichment (HREE/LREE ~1.8-2), flat patterns, and a linear enrichment towards the heavy-REE (HREE/LREE ~1.5-2.5). The MREE enrichment occurred in the high carbonate samples of the Stafford Member overlying the Marcellus Formation. The HREE enrichment occurred in the Union Springs Member of the Marcellus Formation, corresponding to a high TOC peak (TOC ~4.6-6.2 wt%) and moderate carbonate levels (CaCO3 ~4-53 wt%). Results from the sequential leaching experiments suggest that the dominant host of the REEs is the organic fraction of the black shale and that the detrital and authigenic fractions have characteristic MREE enrichments. We present our conclusions on the impact of depositional setting and diagenetic remobilization and authigenic mineral formation on the REE system in the Marcellus Shale.

Preparation and evaluation of GAC-based iron-containing adsorbents for arsenic removal.

PubMed

Gu, Zhimang; Fang, Jun; Deng, Baolin

2005-05-15

Granular activated carbon-based, iron-containing adsorbents (As-GAC) were developed for effective removal of arsenic from drinking water. Granular activated carbon (GAC) was used primarily as a supporting medium for ferric iron that was impregnated by ferrous chloride (FeCl2) treatment, followed by chemical oxidation. Sodium hypochlorite (NaClO) was the most effective oxidant, and carbons produced from steam activation of lignite were most suitable for iron impregnation and arsenic removal. Two As-GAC materials prepared by FeCl2 treatment (0.025 -0.40 M) of Dacro 20 x 50 and Dacro 20 x 40LI resulted in a maximum impregnated iron of 7.89% for Dacro 20 x 50 and 7.65% for Dacro 20 x 40Ll. Nitrogen adsorption-desorption analyses showed the BET specific surface area, total pore volume, porosity, and average mesoporous diameter all decreased with iron impregnation, indicating that some micropores were blocked. SEM studies with associated EDS indicated that the distribution of iron in the adsorbents was mainly on the edge of As-GAC in the low iron content (approximately 1% Fe) sample but extended to the center at the higher iron content (approximately 6% Fe). When the iron content was > approximately 7%, an iron ring formed at the edge of the GAC particles. No difference in X-ray diffraction patterns was observed between untreated GAC and the one with 4.12% iron, suggesting that the impregnated iron was predominantly in amorphous form. As-GAC could remove arsenic most efficiently when the iron content was approximately 6%; further increases of iron decreased arsenic adsorption. The removal of arsenate occurred in a wide range of pH as examined from 4.4 to 11, but efficiency was decreased when pH was higher than 9.0. The presence of phosphate and silicate could significantly decrease arsenate removal at pH > 8.5, while the effects of sulfate, chloride, and fluoride were minimal. Column studies showed that both As(V) and As(III) could be removed to below 10 microg/L within 6000 empty bed volume when the groundwater containing approximately 50 microg/L of arsenic was treated.

Biogeochemistry of aquatic humic substances in Thoreau's Bog, Concord, Massachusetts

USGS Publications Warehouse

McKnight, Diane M.; Thurman, E. Michael; Wershaw, Robert L.; Hemond, Herold

1985-01-01

Thoreau's Bog is an ombrotrophic floating—mat Sphagnum bog developed in a glacial kettlehole and surrounded by a red maple swamp. Concentrations of dissolved organic carbon in the porewater of the bog average 36 mg/L and are greatest near the surface, especially during late summer. This distribution suggest that the upper layer of living and dead Sphagnum and moderately humified peat is the major site of dissolved organic material production in the bog. The dissolved organic material consists mainly of aquatic fulvic acid (67%) and hydrophilic acids (20%); these organic acids control the pH (typically 4 or somewhat lower) of the bogwater. The elemental, amino acid, carbohydrate, and carboxylic acid contents of fulvic acid from the bog are similar to those of aquatic fulvic acid from the nearby Shawsheen River, although the phenolic hydroxyl content of fulvic acid from Thoreau's Bog is higher. The hydrophilic acids have greater amino acid, carbohydrate, and carboxylic acid contents than the fulvic acid, consistent with the hypothesis that hydrophilic acids are more labile intermediate compounds in the formation of fulvic acid.

Can mud (silt and clay) concentration be used to predict soil organic carbon content within seagrass ecosystems?

NASA Astrophysics Data System (ADS)

Serrano, Oscar; Lavery, Paul S.; Duarte, Carlos M.; Kendrick, Gary A.; Calafat, Antoni; York, Paul H.; Steven, Andy; Macreadie, Peter I.

2016-09-01

The emerging field of blue carbon science is seeking cost-effective ways to estimate the organic carbon content of soils that are bound by coastal vegetated ecosystems. Organic carbon (Corg) content in terrestrial soils and marine sediments has been correlated with mud content (i.e., silt and clay, particle sizes < 63 µm), however, empirical tests of this theory are lacking for coastal vegetated ecosystems. Here, we compiled data (n = 1345) on the relationship between Corg and mud contents in seagrass ecosystems (79 cores) and adjacent bare sediments (21 cores) to address whether mud can be used to predict soil Corg content. We also combined these data with the δ13C signatures of the soil Corg to understand the sources of Corg stores. The results showed that mud is positively correlated with soil Corg content only when the contribution of seagrass-derived Corg to the sedimentary Corg pool is relatively low, such as in small and fast-growing meadows of the genera Zostera, Halodule and Halophila, and in bare sediments adjacent to seagrass ecosystems. In large and long-living seagrass meadows of the genera Posidonia and Amphibolis there was a lack of, or poor relationship between mud and soil Corg content, related to a higher contribution of seagrass-derived Corg to the sedimentary Corg pool in these meadows. The relatively high soil Corg contents with relatively low mud contents (e.g., mud-Corg saturation) in bare sediments and Zostera, Halodule and Halophila meadows was related to significant allochthonous inputs of terrestrial organic matter, while higher contribution of seagrass detritus in Amphibolis and Posidonia meadows disrupted the correlation expected between soil Corg and mud contents. This study shows that mud is not a universal proxy for blue carbon content in seagrass ecosystems, and therefore should not be applied generally across all seagrass habitats. Mud content can only be used as a proxy to estimate soil Corg content for scaling up purposes when opportunistic and/or low biomass seagrass species (i.e., Zostera, Halodule and Halophila) are present (explaining 34 to 91 % of variability), and in bare sediments (explaining 78 % of the variability). The results obtained could enable robust scaling up exercises at a low cost as part of blue carbon stock assessments.

Diel changes in the near-surface biomass of zooplankton and the carbon content of vertical migrants

NASA Astrophysics Data System (ADS)

Hays, Graeme C.; Harris, Roger P.; Head, Robert N.

Zooplankton biomass and the carbon content of vertical migrants were measured in the NE Atlantic (36.5°N, 19.2°W) between 11 and 18 July 1996 as part of the Plankton Reactivity in the Marine Environment (PRIME) programme. The increase in zooplankton biomass near the surface (0-100 m) at night compared to during the day suggested that diel vertical migration was an important feature at this site. For three species of vertically migrant copepods, Pleuromamma pisekii, P. gracilis and P. abdominalis, the carbon content of individuals collected at dusk was significantly less than for individuals collected at dawn, with this reduction being 6.2, 7.3 and 14.8%, respectively. This dawn-dusk reduction in carbon content is consistent with the diel pattern of feeding and fasting exhibited by vertical migrants and supports the suggestion that migrating zooplankton will cause an active export of carbon from the surface layers.

Caffeine content of prepackaged national-brand and private-label carbonated beverages.

PubMed

Chou, K-H; Bell, L N

2007-08-01

Caffeine is a well-known stimulant that is added as an ingredient to various carbonated soft drinks. Due to its stimulatory and other physiological effects, individuals desire to know the exact amount of caffeine consumed from these beverages. This study analyzed the caffeine contents of 56 national-brand and 75 private-label store-brand carbonated beverages using high-performance liquid chromatography. Caffeine contents ranged from 4.9 mg/12 oz (IGA Cola) to 74 mg/12 oz (Vault Zero). Some of the more common national-brand carbonated beverages analyzed in this study with their caffeine contents were Coca-Cola (33.9 mg/12 oz), Diet Coke (46.3 mg/12 oz), Pepsi (38.9 mg/12 oz), Diet Pepsi (36.7 mg/12 oz), Dr Pepper (42.6 mg/12 oz), Diet Dr Pepper (44.1 mg/12 oz), Mountain Dew (54.8 mg/12 oz), and Diet Mountain Dew (55.2 mg/12 oz). The Wal-Mart store-brand beverages with their caffeine contents were Sam's Cola (12.7 mg/12 oz), Sam's Diet Cola (13.3 mg/12 oz), Dr Thunder (30.6 mg/12 oz), Diet Dr Thunder (29.9 mg/12 oz), and Mountain Lightning (46.5 mg/12 oz). Beverages from 14 other stores were also analyzed. Most store-brand carbonated beverages were found to contain less caffeine than their national-brand counterparts. The wide range of caffeine contents in carbonated beverages indicates that consumers would benefit from the placement of caffeine values on food labels.

Peat characteristics and groundwater geochemistry of calcareous fens in the Minnesota River Basin, U.S.A

USGS Publications Warehouse

Almendinger, J.E.; Leete, J.H.

1998-01-01

. Calcareous fens in Minnesota are spring-seepage peatlands with a distinctive flora of rare calciphilic species. Peat characteristics and groundwater geochemistry were determined for six calcareous fens in the Minnesota River Basin to better understand the physical structure and chemical processes associated with stands of rare vegetation. Onset of peat accumulation in three of the fens ranged from about 4,700 to 11,000 14C yrs BP and probably resulted from a combination of climate change and local hydrogeologic conditions. Most peat cores had a carbonate-bearing surface zone with greater than 10% carbonates (average 27%, dry wt basis), an underlying carbonate-depleted zone with 10% or less carbonates (average 4%), and a carbonate-bearing lower zone again with greater than 10% carbonates (average 42%). This carbonate zonation was hypothesized to result from the effect of water-table level on carbonate equilibria: carbonate precipitation occurs when the water table is above a critical level, and carbonate dissolution occurs when the water table is lower. Other processes that changed the major ion concentrations in upwelling groundwater include dilution by rain water, sulfate reduction or sulfide oxidation, and ion adsorption or exchange. Geochemical modeling indicated that average shallow water in the calcareous fens during the study period was groundwater mixed with about 6 to 13% rain water. Carbonate precipitation in the surface zone of calcareous fens could be decreased by a number of human activities, especially those that lower the water table. Such changes in shallow water geochemistry could alter the growing conditions that apparently sustain rare fen vegetation.

[Effects of exogenous glucose and starch on soil carbon metabolism of root zone and root function in potted sweet cherry].

PubMed

Zhou, Wen-jie; Zhang, Peng; Qin, Si-jun; Lyu, De-guo

2015-11-01

One-year-old potted sweet cheery trees were treated with 4 g · kg(-1) exogenous glucose or starch and with non-addition of exogenous carbon as the control for up to 60 days. Soil of root zone was sampled to analyze soil microbial biomass carbon, activities of invertase and amylase and microbial community functional diversity during the 60-day treatment, and roots were sampled for analysis of root respiratory rate, respiratory pathways and root viability after treatment for 30 days. Results showed that the invertase activity and the microbial biomass carbon initially increased and decreased subsequently, with the maxima which were 14.0% and 13.1% higher in the glucose treatment than in the control treatment appeared after 15 and 7 days of treatments, respectively. Soil organic matter content increased first then decreased and finally moderately increased again. Amylase activity was 7.5-fold higher in the starch treatment than in the control treatment after 15-day treatment. Soil microbial biomass carbon was higher in the starch treatment than in the control treatment except after 7-day treatment. Soil organic matter content initially increased and then decreased, but it was still 19.8% higher than in the control after 60-day treatment. BIOLOG results showed that the maximum average well color development (AWCD) value and microbial activity appeared after 15-day treatment in the following order: starch>glucose>control. After 30-day treatment, glucose treatment resulted in a significant increase in the soil microbial utilization of carbohydrates, carboxylic acid, amino acids, phenolic acids and amines, and starch treatment significantly increased the soil microbial utilization of carbohydrates, carboxylic acid, polymers and phenolic acids. After 30-day treatment, the total root respiratory rate and root viability were 21.4%, 19.4% and 65.5%, 37.0% higher in glucose treatment than in the control and starch treatments, respectively. These results indicated exogenous glucose and starch affected soil carbon metabolism and enhanced soil microbial activity, the root respiratory rate and root viability.

[Effects of long-term fertilization on pH buffer system of sandy loam calcareous fluvor-aquic soil].

PubMed

Wang, Ji-Dong; Qi, Bing-Jie; Zhang, Yong-Chun; Zhang, Ai-Jun; Ning, Yun-Wang; Xu, Xian-Ju; Zhang, Hui; Ma, Hong-Bo

2012-04-01

Soil samples (0-80 cm) were collected from a 30-year fertilization experimental site in Xuzhou, Jiangsu Province of East China to study the variations of the pH, calcium carbonate and active calcium carbonate contents, and pH buffer capacity of sandy loam calcareous fluvor-aquic soil under different fertilization treatments. Thirty-year continuous application of different fertilizers accelerated the acidification of topsoil (0-20 cm), with the soil pH decreased by 0.41-0.70. Under different fertilization, the soil pH buffer capacity (pHBC) varied from 15.82 to 21.96 cmol x kg(-1). As compared with no fertilization, single N fertilization decreased the pHBC significantly, but N fertilization combined with organic fertilization could significantly increase the pHBC. The soil pHBC had significant positive correlations with soil calcium carbonate and active calcium carbonate contents, but less correlation with soil organic matter content and soil cation exchange capacity, suggesting that after a long-term fertilization, the sandy loam calcareous fluvor-aquic soil was still of an elementary calcium carbonate buffer system, and soil organic matter and cation exchange capacity contributed little to the buffer system. The soil calcium carbonate and active calcium carbonate contents were greater in 0-40 cm than in 40-80 cm soil layer. Comparing with soil calcium carbonate, soil active calcium carbonate was more sensitive to reflect the changes of soil physical and chemical properties, suggesting that the calcium carbonate buffer system could be further classified as soil active calcium carbonate buffer system.

Changes in soil characteristics and C dynamics after mangrove clearing (Vietnam).

PubMed

Grellier, Séraphine; Janeau, Jean-Louis; Dang Hoai, Nhon; Nguyen Thi Kim, Cuc; Le Thi Phuong, Quynh; Pham Thi Thu, Thao; Tran-Thi, Nhu-Trang; Marchand, Cyril

2017-09-01

Of the blue carbon sinks, mangroves have one of the highest organic matter (OM) storage capacities in their soil due to low mineralization processes resulting from waterlogging. However, mangroves are disappearing worldwide because of demographic increases. In addition to the loss of CO 2 fixation, mangrove clearing can strongly affect soil characteristics and C storage. The objectives of the present study were to quantify the evolution of soil quality, carbon stocks and carbon fluxes after mangrove clearing. Sediment cores to assess physico-chemical properties were collected and in situ CO 2 fluxes were measured at the soil-air interface in a mangrove of Northern Vietnam. We compared a Kandelia candel mangrove forest with a nearby zone that had been cleared two years before the study. Significant decrease of clay content and an increase in bulk density for the upper 35cm in the cleared zone were observed. Soil organic carbon (OC) content in the upper 35cm decreased by >65% two years after clearing. The quantity and the quality of the carbon changed, with lower carbon to nitrogen ratios, indicating a more decomposed OM, a higher content of dissolved organic carbon, and a higher content of inorganic carbon (three times higher). This highlights the efficiency of mineralization processes following clearing. Due to the rapid decrease in the soil carbon content, CO 2 fluxes at sediment interface were >50% lower in the cleared zone. Taking into account carbonate precipitation after OC mineralization, the mangrove soil lost ~10MgOCha -1 yr -1 mostly as CO 2 to the atmosphere and possibly as dissolved forms towards adjacent ecosystems. The impacts on the carbon cycle of mangrove clearing as shown by the switch from a C sink to a C source highlight the importance of maintaining these ecosystems, particularly in a context of climate change. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of carbon nanofibers on the infiltration and thermal conductivity of carbon/carbon composites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Jinsong, E-mail: lijinsong@buaa.edu.cn; School of Physics and Nuclear Energy Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100191; Luo, Ruiying, E-mail: ryluo@buaa.edu.cn

Highlights: {yields} The CNFs improve the infiltration rate and thermal properties of carbon/carbon composites. {yields} The densification rate increases with the CNF content increasing at the beginning of infiltration. {yields} The values of the thermal conductivity of the composite obtain their maximum values at 5 wt.%. -- Abstract: Preforms containing 0, 5, 10, 15 and 20 wt.% carbon nanofibers (CNFs) were fabricated by spreading layers of carbon cloth, and infiltrated using the electrified preform heating chemical vapor infiltration method (ECVI) under atmospheric pressure. Initial thermal gradients were determined. Resistivity and density evolutions with infiltration time have been recorded. Scanning electronmore » microscopy, polarized light micrograph and X-ray diffraction technique were used to analyze the experiment results. The results showed that the infiltration rate increased with the rising of CNF content, and after 120 h of infiltration, the density was the highest when the CNF content was 5 wt.%, but the composite could not be densified efficiently as the CNF content ranged from 10 wt.% to 20 wt.%. CNF-reinforced C/C composites have enhanced thermal conductivity, the values at 5 wt.% were increased by nearly 5.5-24.1% in the X-Y direction and 153.8-251.3% in the Z direction compared to those with no CNFs. When the additive content was increased to 20 wt.%, due to the holes and cavities in the CNF web and between carbon cloth and matrix, the thermal conductivities in the X-Y and Z directions decreased from their maximum values at 5 wt.%.« less

Structural Evolution of Q-Carbon and Nanodiamonds

NASA Astrophysics Data System (ADS)

Gupta, Siddharth; Bhaumik, Anagh; Sachan, Ritesh; Narayan, Jagdish

2018-04-01

This article provides insights pertaining to the first-order phase transformation involved in the growth of densely packed Q-carbon and nanodiamonds by nanosecond laser melting and quenching of diamond-like carbon (DLC) thin films. DLC films with different sp 3 content were melted rapidly in a controlled way in super-undercooled state and quenched, leading to formation of distinct nanostructures, i.e., nanodiamonds, Q-carbon, and Q-carbon nanocomposites. This analysis provides direct evidence of the dependence of the super-undercooling on the structural evolution of Q-carbon. Finite element heat flow calculations showed that the super-undercooling varies monotonically with the sp 3 content. The phenomenon of solid-liquid interfacial instability during directional solidification from the melt state is studied in detail. The resulting lateral segregation leads to formation of cellular filamentary Q-carbon nanostructures. The dependence of the cell size and wavelength at the onset of instability on the sp 3 content of DLC thin films was modeled based on perturbation theory.

Relationships between the structure of natural organic matter and its reactivity towards molecular ozone and hydroxyl radicals

USGS Publications Warehouse

Westerhoff, P.; Aiken, G.; Amy, G.; Debroux, J.

1999-01-01

Oxidation reaction rate parameters for molecular ozone (O3) and hydroxyl (HO) radicals with a variety of hydrophobic organic acids (HOAs) isolated from different geographic locations were determined from batch ozonation studies. Rate parameter values, obtained under equivalent dissolved organic carbon concentrations in both the presence and absence of non-NOM HO radical scavengers, varied as a function of NOM structure. First-order rate constants for O3 consumption (k(O3)) averaged 8.8 x 10-3 s-1, ranging from 3.9 x 10-3 s-1 for a groundwater HOA to > 16 x 10-3 s-1 for river HOAs with large terrestrial carbon inputs. The average second-order rate constant (k(HO,DOC) between HO radicals and NOM was 3.6 x 108 l (mol C)-1 s-1; a mass of 12 g C per mole C was used in all calculations. Specific ultraviolet absorbance (SUVA) at 254 or 280 nm of the HOAs correlated well (r > 0.9) with O3 consumption rate parameters, implying that organic ??-electrons strongly and selectively influence oxidative reactivity. HO radical reactions with NOM were less selective, although correlation between k(HO,DOC) and SUVA existed. Other physical-chemical properties of NOM, such as aromatic and aliphatic carbon content from 13C-NMR spectroscopy, proved less sensitive for predicting oxidation reactivity than SUVA. The implication of this study is that the structural nature of NOM varies temporally and spatially in a water source, and both the nature and amount of NOM will influence oxidation rates.

Soil Organic Carbon Estimation and Mapping Using "on-the-go" VisNIR Spectroscopy

NASA Astrophysics Data System (ADS)

Brown, D. J.; Bricklemyer, R. S.; Christy, C.

2007-12-01

Soil organic carbon (SOC) and other soil properties related to carbon sequestration (eg. soil clay content and mineralogy) vary spatially across landscapes. To cost effectively capture this variability, new technologies, such as Visible and Near Infrared (VisNIR) spectroscopy, have been applied to soils for rapid, accurate, and inexpensive estimation of SOC and other soil properties. For this study, we evaluated an "on the go" VisNIR sensor developed by Veris Technologies, Inc. (Salinas, KS) for mapping SOC, soil clay content and mineralogy. The Veris spectrometer spanned 350 to 2224 nm with 8 nm spectral resolution, and 25 spectra were integrated every 2 seconds resulting in 3 -5 m scanning distances on the ground. The unit was mounted to a mobile sensor platform pulled by a tractor, and scanned soils at an average depth of 10 cm through a quartz-sapphire window. We scanned eight 16.2 ha (40 ac) wheat fields in north central Montana (USA), with 15 m transect intervals. Using random sampling with spatial inhibition, 100 soil samples from 0-10 cm depths were extracted along scanned transects from each field and were analyzed for SOC. Neat, sieved (<2 mm) soil sample materials were also scanned in the lab using an Analytical Spectral Devices (ASD, Boulder, CO, USA) Fieldspec Pro FR spectroradiometer with a spectral range of 350-2500 and spectral resolution of 2-10 nm. The analyzed samples were used to calibrate and validate a number of partial least squares regression (PLSR) VisNIR models to compare on-the-go scanning vs. higher spectral resolution laboratory spectroscopy vs. standard SOC measurement methods.

Spatially explicit simulation of peatland hydrology and carbon dioxide exchange: Influence of mesoscale topography

NASA Astrophysics Data System (ADS)

Sonnentag, O.; Chen, J. M.; Roulet, N. T.; Ju, W.; Govind, A.

2008-06-01

Carbon dynamics in peatlands are controlled, in large part, by their wetness as defined by water table depth and volumetric liquid soil moisture content. A common type of peatland is raised bogs that typically have a multiple-layer canopy of vascular plants over a Sphagnum moss ground cover. Their convex form restricts water supply to precipitation and water is shed toward the margins, usually by lateral subsurface flow. The hydraulic gradient for lateral subsurface flow is governed by the peat surface topography at the mesoscale (˜200 m to 5 km). To investigate the influence of mesoscale topography on wetness, evapotranspiration (ET), and gross primary productivity (GPP) in a bog during the snow-free period, we compare the outputs of a further developed version of the daily Boreal Ecosystem Productivity Simulator (BEPS) with observations made at the Mer Bleue peatland, located near Ottawa, Canada. Explicitly considering mesoscale topography, simulated total ET and GPP correlate well with measured ET (r = 0.91) and derived gross ecosystem productivity (GEP; r = 0.92). Both measured ET and derived GEP are simulated similarly well when mesoscale topography is neglected, but daily simulated values are systematically underestimated by about 10% and 12% on average, respectively, due to greater wetness resulting from the lack of lateral subsurface flow. Owing to the differences in moss surface conductances of water vapor and carbon dioxide with increasing moss water content, the differences in the spatial patterns of simulated total ET and GPP are controlled by the mesotopographic position of the moss ground cover.

Sources of variance in BC mass measurements from a small marine engine: Influence of the instruments, fuels and loads

NASA Astrophysics Data System (ADS)

Jiang, Yu; Yang, Jiacheng; Gagné, Stéphanie; Chan, Tak W.; Thomson, Kevin; Fofie, Emmanuel; Cary, Robert A.; Rutherford, Dan; Comer, Bryan; Swanson, Jacob; Lin, Yue; Van Rooy, Paul; Asa-Awuku, Akua; Jung, Heejung; Barsanti, Kelley; Karavalakis, Georgios; Cocker, David; Durbin, Thomas D.; Miller, J. Wayne; Johnson, Kent C.

2018-06-01

Knowledge of black carbon (BC) emission factors from ships is important from human health and environmental perspectives. A study of instruments measuring BC and fuels typically used in marine operation was carried out on a small marine engine. Six analytical methods measured the BC emissions in the exhaust of the marine engine operated at two load points (25% and 75%) while burning one of three fuels: a distillate marine (DMA), a low sulfur, residual marine (RMB-30) and a high-sulfur residual marine (RMG-380). The average emission factors with all instruments increased from 0.08 to 1.88 gBC/kg fuel in going from 25 to 75% load. An analysis of variance (ANOVA) tested BC emissions against instrument, load, and combined fuel properties and showed that both engine load and fuels had a statistically significant impact on BC emission factors. While BC emissions were impacted by the fuels used, none of the fuel properties investigated (sulfur content, viscosity, carbon residue and CCAI) was a primary driver for BC emissions. Of the two residual fuels, RMB-30 with the lower sulfur content, lower viscosity and lower residual carbon, had the highest BC emission factors. BC emission factors determined with the different instruments showed a good correlation with the PAS values with correlation coefficients R2 >0.95. A key finding of this research is the relative BC measured values were mostly independent of load and fuel, except for some instruments in certain fuel and load combinations.

Site-specific 13C content by quantitative isotopic 13C nuclear magnetic resonance spectrometry: a pilot inter-laboratory study.

PubMed

Chaintreau, Alain; Fieber, Wolfgang; Sommer, Horst; Gilbert, Alexis; Yamada, Keita; Yoshida, Naohiro; Pagelot, Alain; Moskau, Detlef; Moreno, Aitor; Schleucher, Jürgen; Reniero, Fabiano; Holland, Margaret; Guillou, Claude; Silvestre, Virginie; Akoka, Serge; Remaud, Gérald S

2013-07-25

Isotopic (13)C NMR spectrometry, which is able to measure intra-molecular (13)C composition, is of emerging demand because of the new information provided by the (13)C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic (13)C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular (13)C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic (13)C NMR was then assessed on vanillin from three different origins associated with specific δ (13)Ci profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ (13)Ci in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results. Copyright © 2013 Elsevier B.V. All rights reserved.

Atmospheric measurement of point source fossil fuel CO2 emissions

NASA Astrophysics Data System (ADS)

Turnbull, J. C.; Keller, E. D.; Baisden, W. T.; Brailsford, G.; Bromley, T.; Norris, M.; Zondervan, A.

2013-11-01

We use the Kapuni Gas Treatment Plant to examine methodologies for atmospheric monitoring of point source fossil fuel CO2 (CO2ff) emissions. The Kapuni plant, located in rural New Zealand, removes CO2 from locally extracted natural gas and vents that CO2 to the atmosphere, at a rate of ~0.1 Tg carbon per year. The plant is located in a rural dairy farming area, with no other significant CO2ff sources nearby, but large, diurnally varying, biospheric CO2 fluxes from the surrounding highly productive agricultural grassland. We made flask measurements of CO2 and 14CO2 (from which we derive the CO2ff component) and in situ measurements of CO2 downwind of the Kapuni plant, using a Helikite to sample transects across the emission plume from the surface up to 100 m a.g.l. We also determined the surface CO2ff content averaged over several weeks from the 14CO2 content of grass samples collected from the surrounding area. We use the WindTrax plume dispersion model to compare the atmospheric observations with the emissions reported by the Kapuni plant, and to determine how well atmospheric measurements can constrain the emissions. The model has difficulty accurately capturing the fluctuations and short-term variability in the Helikite samples, but does quite well in representing the observed CO2ff in 15 min averaged surface flask samples and in ~1 week integrated CO2ff averages from grass samples. In this pilot study, we found that using grass samples, the modeled and observed CO2ff emissions averaged over one week agreed to within 30%. The results imply that greater verification accuracy may be achieved by including more detailed meteorological observations and refining 14CO2 sampling strategies.

Atmospheric measurement of point source fossil CO2 emissions

NASA Astrophysics Data System (ADS)

Turnbull, J. C.; Keller, E. D.; Baisden, T.; Brailsford, G.; Bromley, T.; Norris, M.; Zondervan, A.

2014-05-01

We use the Kapuni Gas Treatment Plant to examine methodologies for atmospheric monitoring of point source fossil fuel CO2 (CO2ff) emissions. The Kapuni plant, located in rural New Zealand, removes CO2 from locally extracted natural gas and vents that CO2 to the atmosphere, at a rate of ~0.1 Tg carbon per year. The plant is located in a rural dairy farming area, with no other significant CO2ff sources nearby, but large, diurnally varying, biospheric CO2 fluxes from the surrounding highly productive agricultural grassland. We made flask measurements of CO2 and 14CO2 (from which we derive the CO2ff component) and in situ measurements of CO2 downwind of the Kapuni plant, using a Helikite to sample transects across the emission plume from the surface up to 100 m above ground level. We also determined the surface CO2ff content averaged over several weeks from the 14C content of grass samples collected from the surrounding area. We use the WindTrax plume dispersion model to compare the atmospheric observations with the emissions reported by the Kapuni plant, and to determine how well atmospheric measurements can constrain the emissions. The model has difficulty accurately capturing the fluctuations and short-term variability in the Helikite samples, but does quite well in representing the observed CO2ff in 15 min averaged surface flask samples and in ~ one week integrated CO2ff averages from grass samples. In this pilot study, we found that using grass samples, the modeled and observed CO2ff emissions averaged over one week agreed to within 30%. The results imply that greater verification accuracy may be achieved by including more detailed meteorological observations and refining 14C sampling strategies.

Influence of the environmental factors on the intensity of the oxygen, ammonium, and phosphate metabolism in the agar-containing seaweed Ahnfeltia tobuchiensis (Ahnfeltiales, Rhodophyta)

NASA Astrophysics Data System (ADS)

Cherbadgy, I. I.; Sabitova, L. I.

2011-02-01

A complex study of the influence of various environmental factors on the rate of the oxygen (MO 2), ammonium (MNH 4), and phosphate (MPO 4) metabolism in Ahnfeltia tobuchiensis has been carried out in situ in the Izmena Bay of Kunashir Island. The following environmental factors have been included into the investigation: the photosynthetically active radiation (PAR); the ammonium (NH4); the phosphate (PO4); and the tissue content of carbon (C), nitrogen (N), phosphorus (P), and chlorophyll a (Chl). The population of agar-containing seaweed A. tobuchiensis forms a layer with a thickness up to 0.5 m, which occupies about 23.3 km2; the population's biomass is equal to 125000 tons. The quantitative assessment of the organic matter production and nutrient consumption during the oxygen metabolism (MO 2) has been carried out for the whole population. It has been shown that the daily rate depends on the PAR intensity, the seawater concentrations of PO4 and NH4, and the tissue content of N and P ( r 2 = 0.78, p < 0.001). The daily NH4 consumption averages 0.21 μmol/(gDW h) and depends on the NH4 and O2 concentrations in the seawater and on the C and Chl a content in the algal tissues ( r 2 = 0.64, p < 0.001). The daily PO4 consumption averages 0.01 μmol/(gDW h) and depends on the NH4 concentration in the seawater and on the P content in the algal tissues ( r 2 = 0.40, p < 0.001).

Selected constituents in the smokes of foreign commercial cigaretts: tar, nicotine, carbon monoxide, and carbon dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jenkins, R.A.; Quincy, R.B.; Guerin, M.R.

The tar, nicotine, carbon monoxide, and carbon dioxide contents of the smokes of 220 brands of foreign commercial cigarettes are reported. In some instances, filter cigarettes of certain brands were found to deliver as much or more smoke constituents than their nonfilter counterparts. Also, data indicated that there can be a great variation in the tar, nicotine, or carbon monoxide content of the smoke of samples of a given brand of cigarettes, depending on the nation in which they are purchased. 24 tables.

[Humus composition and stable carbon isotope natural abundance in paddy soil under long-term fertilization].

PubMed

Ma, Li; Yang, Lin-Zhang; Ci, En; Wang, Yan; Yin, Shi-Xue; Shen, Ming-Xing

2008-09-01

Soil samples were collected from an experimental paddy field with long-term (26 years) fertilization in Taihu Lake region of Jiangsu Province to study the effects of different fertilization on the organic carbon distribution and stable carbon isotope natural abundance (delta 13C) in the soil profile, and on the humus composition. The results showed that long-term fertilization increased the organic carbon content in top soil significantly, and there was a significantly negative exponential correlation between soil organic carbon content and soil depth (P < 0.01). The organic carbon content in 10-30 cm soil layer under chemical fertilizations and in 20-40 cm soil layer under organic fertilizations was relatively stable. Soil delta 13C increased gradually with soil depth, its variation range being from -24% per thousand to -28 per thousand, and had a significantly negative linear correlation with soil organic carbon content (P < 0.05). In 0-20 cm soil layer, the delta 13C in treatments organic manure (M), M + NP, M + NPK, M + straw (R) + N, and R + N decreased significantly; while in 30-50 cm soil layer, the delta 13C in all organic fertilization treatments except R + N increased significantly. Tightly combined humus (humin) was the main humus composition in the soil, occupying 50% or more, and the rest were loosely and stably combined humus. Long-term fertilization increased the content of loosely combined humus and the ratio of humic acid (HA) to fulvic acid (FA).

Properties of carbon composite paper derived from coconut coir as a function of polytetrafluoroethylene content

NASA Astrophysics Data System (ADS)

Destyorini, Fredina; Indriyati; Indayaningsih, Nanik; Prihandoko, Bambang; Zulfia Syahrial, Anne

2018-03-01

The carbon composite papers were produced by utilizing carbon materials from coconut coir. In the present work, carbon composite papers (CCP) were prepared by mixing carbon materials in the form of powder and fibre with polymer (ethylene vinyl acetate and polyethylene glycol) in xylene at 100°C. Then, polytetrafluoroethylene (PTFE) with different content was used to treat the surface of CCP. The properties of PTFE-coated CCP were analysed by means of contact angle measurement, tensile testing, porosity, density, and electrical conductivity measurements. As expected, all CCP’s surfaces treated with PTFE were found to be hydrophobic with contact angle >120° and relatively constant during 60 minutes measurement. Furthermore, water contact angle, density, and mechanical properties of CCP generally increase with increasing PTFE content. However, the porosity and electrical conductivity of CCP decrease slightly as the PTFE content increased from 0 wt% to 30 wt%. Based on the observation and analysis, the optimum PTFE content on CCP was 20 %, in which the mechanical properties and hydrophobicity behaviour were improved significantly, but it was only caused a very small drop in porosity and electrical conductivity

Carbon, nitrogen, and phosphorus stoichiometry of plankton and the nutrient regime in Cabo Frio Bay, SE Brazil.

PubMed

Kütter, Vinicius T; Wallner-Kersanach, Monica; Sella, Silvia M; Albuquerque, Ana Luiza S; Knoppers, Bastiaan A; Silva-Filho, Emmanoel V

2014-01-01

This long-term study, performed during the years 2003-2005 and 2008-2009, investigated the carbon (C), nitrogen (N), and phosphorus (P) contents of the phyto- and zooplankton communities and the nutrient regime of Cabo Frio Bay, SE Brazil. The information intends to serve as baseline of the plankton C, N, and P stoichiometry for the calibration of biogeochemical and ecological models in support to future findings related to the local and regional phenomena of climatic change. Cabo Frio Bay is a small semienclosed system set adjacent to a region subject to sporadic coastal upwelling. Zooplankton exhibited average annual C, N, and P contents of 11.6 ± 6.9 %, 2.8 ± 1.8 %, and 0.18 ± 0.08 %, and phytoplankton (>20 μm) 6.8 ± 6.0 %, 1.6 ± 1.5 %, and 0.09 ± 0.08 %, respectively. The C/N/P ratios correspond to the lowest already found to date for a marine environment. The low C contents must have been brought about by a predominance of gelatinous zooplankton, like Doliolids/ Salps and also Pteropods. Average annual nutrient concentrations in the water were 0.21 ± 0.1 μM for phosphate, 0.08 ± 0.1 μM for nitrite, 0.74 ± 1.6 μM for nitrate, and 1.27 ± 1.1 μM for ammonium. N/P ratios were around 8:1 during the first study period and 12:1 during the second. The plankton C/N/P and N/P nutrient ratios and elemental concentrations suggest that the system was oligotrophic and nitrogen limited. The sporadic intrusions of upwelling waters during the first study period had no marked effect upon the systems metabolism, likely due to dilution effects and the short residence times of water of the bay.

Effect of Melting Iron-Based Alloy Temperature on Carbon Content Observed in Laser-Induced Breakdown Spectroscopy

NASA Astrophysics Data System (ADS)

Lin, Xiaomei; Chang, Penghui; Chen, Gehua; Lin, Jingjun; Liu, Ruixiang; Yang, Hao

2015-11-01

Our recent work has determined the carbon content in a melting ferroalloy by laser-induced breakdown spectroscopy (LIBS). The emission spectrum of carbon that we obtained in the laboratory is suitable for carbon content determination in a melting ferroalloy but we cannot get the expected results when this method is applied in industrial conditions: there is always an unacceptable error of around 4% between the actual value and the measured value. By comparing the measurement condition in the industrial condition with that in the laboratory, the results show that the temperature of the molten ferroalloy samples to be measured is constant under laboratory conditions while it decreases gradually under industrial conditions. However, temperature has a considerable impact on the measurement of carbon content, and this is the reason why there is always an error between the actual value and the measured value. In this paper we compare the errors of carbon content determination at different temperatures to find the optimum reference temperature range which can fit the requirements better in industrial conditions and, hence, make the measurement more accurate. The results of the comparative analyses show that the measured value of the carbon content in molten state (1620 K) is consistent with the nominal value of the solid standard sample (error within 0.7%). In fact, it is the most accurate measurement in the solid state. Based on this, we can effectively improve the accuracy of measurements in laboratory and can provide a reference standard of temperature for the measurement in industrial conditions. supported by National Natural Science Foundation of China (No. 51374040), and supported by Laser-Induced Plasma Spectroscopy Equipment Development and Application, China (No. 2014YQ120351)

Local Environmental Factors Drive Divergent Grassland Soil Bacterial Communities in the Western Swiss Alps.

PubMed

Yashiro, Erika; Pinto-Figueroa, Eric; Buri, Aline; Spangenberg, Jorge E; Adatte, Thierry; Niculita-Hirzel, Hélène; Guisan, Antoine; van der Meer, Jan Roelof

2016-11-01

Mountain ecosystems are characterized by a diverse range of climatic and topographic conditions over short distances and are known to shelter a high biodiversity. Despite important progress, still little is known on bacterial diversity in mountain areas. Here, we investigated soil bacterial biogeography at more than 100 sampling sites randomly stratified across a 700-km 2 area with 2,200-m elevation gradient in the western Swiss Alps. Bacterial grassland communities were highly diverse, with 12,741 total operational taxonomic units (OTUs) across 100 sites and an average of 2,918 OTUs per site. Bacterial community structure was correlated with local climatic, topographic, and soil physicochemical parameters with high statistical significance. We found pH (correlated with % CaO and % mineral carbon), hydrogen index (correlated with bulk gravimetric water content), and annual average number of frost days during the growing season to be among the groups of the most important environmental drivers of bacterial community structure. In contrast, bacterial community structure was only weakly stratified as a function of elevation. Contrasting patterns were discovered for individual bacterial taxa. Acidobacteria responded both positively and negatively to pH extremes. Various families within the Bacteroidetes responded to available phosphorus levels. Different verrucomicrobial groups responded to electrical conductivity, total organic carbon, water content, and mineral carbon contents. Alpine grassland bacterial communities are thus highly diverse, which is likely due to the large variety of different environmental conditions. These results shed new light on the biodiversity of mountain ecosystems, which were already identified as potentially fragile to anthropogenic influences and climate change. This article addresses the question of how microbial communities in alpine regions are dependent on local climatic and soil physicochemical variables. We benefit from a unique 700-km 2 study region in the western Swiss Alps region, which has been exhaustively studied for macro-organismal and fungal ecology, and for topoclimatic modeling of future ecological trends, but without taking into account soil bacterial diversity. Here, we present an in-depth biogeographical characterization of the bacterial community diversity in this alpine region across 100 randomly stratified sites, using 56 environmental variables. Our exhaustive sampling ensured the detection of ecological trends with high statistical robustness. Our data both confirm previously observed general trends and show many new detailed trends for a wide range of bacterial taxonomic groups and environmental parameters. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Comparison between Single-Walled CNT, Multi-Walled CNT, and Carbon Nanotube-Fiber Pyrograf III

NASA Astrophysics Data System (ADS)

Mousa, Marwan S.

2018-02-01

Single-Walled CNT (SWCNTs), Multi-walled Carbon Nanotubes (MWCNTs), and Carbon Nanotube-Fibers Pyrograf III PR-1 (CNTFs) were deposited by chemical vapor deposition under vacuum pressure value of (10-7mbar). Their structures were investigated by field emission microscopy. Carbon Nano-Fibers Pyrograf III PR-1 showed an average fiber diameter within the range of 100-200 nm and a length of (30-100) μm. Single-walled Carbon Nanotubes were produced by high-pressure Carbon Monoxide process with an average diameter ranging between (1-4) nm and a length of (1-3) μm. Thin Multiwall Carbon Nanotube of carbon purity (90%) showed an average diameter tube (9.5 nm) with a high-aspect-ratio (>150). The research work reported here includes the field electron emission current-voltage (I-V) characteristics and presented as Fowler-Nordheim (FN) plots and the spatial emission current distributions (electron emission images) obtained and analyzed in terms of electron source features. For the three types of emitters, a single spot pattern for the electron spatial; distributions were observed, with emission current fluctuations in some voltage region.

Can the capacity for isoprene emission acclimate to environmental modifications during autumn senescence in temperate deciduous tree species Populus tremula?

PubMed

Sun, Zhihong; Copolovici, Lucian; Niinemets, Ülo

2012-03-01

Changes in isoprene emission (Φ(isoprene)), and foliage photosynthetic (A) rates, isoprene precursor dimethylallyldiphosphate (DMADP), and nitrogen and carbon contents were studied from late summer to intensive leaf fall in Populus tremula to gain insight into the emission controls by temperature and endogenous, senescence-induced, modifications. Methanol emissions, characterizing degradation of cell wall pectins, were also measured. A rapid reduction in Φ(isoprene) and A of 60-70% of the initial value was observed in response to a rapid reduction of ambient temperature by ca. 15°C (cold stress). Later phases of senescence were associated with further reductions in Φ(isoprene) and A, with simultaneous major decrease in nitrogen content. However, during episodes of temperature increase, A and in particular, Φ(isoprene) partly recovered. Variation in Φ(isoprene) during senescence was correlated with average temperature of preceding days, with the highest degree of explained variance observed with average temperature of 6 days. Throughout the study, methanol emissions were small, but a large burst of methanol emission was associated with leaf yellowing and abscission. Overall, these data demonstrate that the capacity for isoprene emission can adjust to environmental conditions in senescing leaves as well, but the responsiveness is low compared with mid-season and is also affected by stress.

Hydrocarbon status of soils in the asphalt deposit area (Samara Bend)

NASA Astrophysics Data System (ADS)

Pikovskiy, Yu. I.; Gennadiev, A. N.; Kovach, R. G.; Zhidkin, A. P.; Khlynina, N. I.; Kiseleva, A. Yu.

2017-04-01

The composition and distribution features of the main components of soil hydrocarbon complex― organic (noncarbonate) carbon, hexane bitumoids, and individual polycyclic aromatic hydrocarbons (PAHs)―in the area of depleted Bakhilovo asphalt deposit (Samara oblast) have been studied. According to their proportions, three genetic types of soil hydrocarbon status are distinguished: (a) emanation-injection type prevailing within the limits of the former production field and characterized by anomalous contents of heavy resinous bitumoids (5000-7000 mg/kg on the average) throughout the soil profile and a high content of PAHs (4-9 mg/kg on the average, 29 mg/kg as the maximum, with the dominance of naphthalene homologues); (b) emanation-biogeochemical type confined to mechanogenically undisturbed soils within and beyond the deposit area, where the emanation component is manifested in soils with heavy texture and higher concentrations and very light composition of bitumoids in the lower parts of the soil profile; and (c) atmosedimentation-biogeochemical type characteristic of conventionally background soils with light texture; benzo[ a]pyrene traces are detected among PAHs in the upper soil horizon, which indicates the input of this hydrocarbon with aerosols from the atmosphere; the concentrations of bitumoids and PAHs in parent rocks are lower than in the soils.

Methylmercury content of eggs in yellow perch related to maternal exposure in four Wisconsin lakes

USGS Publications Warehouse

Hammerschmidt, Chad R.; Wiener, James G.; Frazier, Brdaley E.; Rada, Ronald G.

1999-01-01

We examined the influence of maternal mercury and selected lacustrine variables on the mercury content of eggs from yellow perch (Perca flavescens). Total mercury, methylmercury, and inorganic mercury were determined in eggs and carcasses (less eggs) from three seepage lakes with a pH range of 6.1a??7.0 and a fourth lake in which pH was experimentally increased from 5.5 to 6.8 by addition of alkaline groundwater. The concentration of total mercury in eggs was strongly correlated with that in the maternal carcass. Concentrations and burdens of mercury in eggs and carcasses were inversely correlated with lake water pH, acid-neutralizing capacity, calcium, and dissolved organic carbon. In eggs containing more than 30 ng/g dry weight (4.5 ng/g wet weight) of total mercury, methylmercury averaged 91% of total mercury and ranged from 85% to 96%. Mean burdens of total mercury in individual eggs varied greatly among lakes (range, 2.3a??63 pg), and the egg mass averaged 1.9% of the whole-body burden. We conclude that exposure of the developing yellow perch embryo to methylmercury is strongly affected by maternal bioaccumulation, which can vary substantially among and within lakes; however, the toxicological significance of the observed exposure of embryos to methylmercury is unclear.

Methylmercury content of eggs in yellow perch related to maternal exposure in four Wisconsin lakes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammerschmidt, C.R.; Frazier, B.E.; Rada, R.G.

1999-04-01

The authors examined the influence of maternal mercury and selected lacustrine variables on the mercury content of eggs from yellow perch (Perca flavescens). Total mercury, methylmercury, and inorganic mercury were determined in eggs and carcasses (less eggs) from three seepage lakes with a pH range of 6.1--7.0 and a fourth lake in which pH was experimentally increased from 5.5 to 6.8 by addition of alkaline groundwater. The concentration of total mercury in eggs was strongly correlated with that in the material carcass. Concentrations and burdens of mercury in eggs and carcasses were inversely correlated with lake water pH, acid-neutralizing capacity,more » calcium, and dissolved organic carbon. In eggs containing more than 30 ng/g dry weight of total mercury, methylmercury averaged 91% of total mercury and ranged from 85% to 96%. Mean burdens of total mercury in individual eggs varied greatly among lakes and the egg mass averaged 1.9% of the whole-body burden. The authors conclude that exposure of the developing yellow perch embryo to methylmercury is strongly affected by maternal bioaccumulation, which can vary substantially among and within lakes; however, the toxicological significance of the observed exposure of embryos to methylmercury is unclear.« less

Selection of pecan shell-based activated carbons for removal of organic and inorganic impurities from water.

PubMed

Niandou, Mohamed A S; Novak, Jeffrey M; Bansode, Rishipal R; Yu, Jianmei; Rehrah, Djaafar; Ahmedna, Mohamed

2013-01-01

Activated carbons are a byproduct from pyrolysis and have value as a purifying agent. The effectiveness of activated carbons is dependent on feedstock selection and pyrolysis conditions that modify their surface properties. Therefore, pecan shell-based activated carbons (PSACs) were prepared by soaking shells in 50% (v/v) HPO or 25 to 50% of KOH-NaHCO followed by pyrolysis at 400 to 700°C under a N atmosphere. Physically activated PSACs were produced by pyrolysis at 700°C under N followed by activation with steam or CO at 700 to 900°C. Physicochemical, surface, and adsorption properties of the PSACs were compared with two commercially available activated carbons. The average mass yield of PSACs with respect to the initial mass of the biomass was about 20 and 34% for physically activated and chemically activated carbons, respectively. Acid-activated carbons exhibited higher surface area, higher bulk density, and lower ash content compared with steam- or CO-activated carbons and the two commercial products. Base activation led to the development of biochar with moderate to high surface area with surface charges suitable for adsorption of anionic species. Regardless of the activation method, PSACs had high total surface area ranging from 400 to 1000 m g, better pore size distribution, and more surface charges than commercial samples. Our results also showed that PSACs were effective in removing inorganic contaminants such as Cu and NO as well as organic contaminants such as atrazine and metolachlor. This study showed that pyrolysis conditions and activation had a large influence on the PSAC's surface characteristics, which can limit its effectiveness as a custom sorbent for targeted water contaminants. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

[Effects of tillage rotation and fertilization on soil aggregates and organic carbon content in corn field in Weibei Highland].

PubMed

Wang, Li; Li, Jun; Li, Juan; Bai, Wei-Xia

2014-03-01

A field experiment on effects of tillage rotation and fertilization on corn continuous cropping-practiced lands was carried out in Heyang of Shaanxi in 2007-2012. The tillage types included annual rotation of no-tillage and subsoiling (NT-ST), subsoiling and conventional tillage (ST-CT), or conventional tillage and no-tillage (CT-NT), and yearly practice of no tillage (NT-NT), subsoiling (ST-ST) or conventional tillage (CT-CT). The fertilization treatments included balanced fertilization, low-rate fertilization and conventional fertilization, which were separately practiced against the different tillage types. The experiment investigated compositions, mean mass diameters (MWD), geometrical mean diameters (GMD) and fraction dimension numbers (D) of soil aggregates in 0-40 cm soil and contents of organic carbon in 0-60 cm soil. The results indicated that: 1) The increased tillage intensity caused the reduced mechanical stability and content of soil aggregates and increased soil organic carbon loss. No-tillage or tillage rotation increased the MWD, GMD and contents of soil organic carbon and soil aggregates with diameters of more than 0.25 mm, but decreased D. Under the same fertilization treatment, the contents of soil aggregates with diameters of more than 0.25 mm were ranked in the order of NT-NT>NT-ST>NT-CT>ST-ST>CT-ST>CT-CT, and under the same tillage rotations, the soil aggregates were more stable with the balanced or low- rate fertilization than with the conventional fertilization. 2) Mathematical fractal dimension fitting of soil aggregates indicated that the fractal dimension numbers of soil aggregates ranged within 2.247-2.681 by dry sieving and 2.897-2.976 by wet sieving. In 0-30 cm soil, the fractal dimension numbers of soil aggregates were significantly lower under no-tillage or tillage rotation than under conventional tillage, and in 0-40 cm soil, the fractal dimensions of soil aggregates increased with soil depth, and tended to stabilize at the soil depth of 40 cm. 3) The different fertilization treatments exerted significantly different influences on the contents of soil organic carbon (P < 0.05), which tended to decline with soil depth. Compared to the conventional fertilization, the balanced fertilization increased the content of soil organic carbon by 6.9%, and the contents of soil organic carbon increased as the diameters of soil aggregates increased. The correlation analysis showed that the contents of soil aggregates with diameters of 0.25-2 mm significantly affected the content of soil organic carbon, with the coefficient of determination being 0.848 (P < 0.01).

An Improved Variant of Soybean Type 1 Diacylglycerol Acyltransferase Increases the Oil Content and Decreases the Soluble Carbohydrate Content of Soybeans[OPEN

PubMed Central

Shen, Bo; Damude, Howard G.; Everard, John D.; Booth, John R.

2016-01-01

Kinetically improved diacylglycerol acyltransferase (DGAT) variants were created to favorably alter carbon partitioning in soybean (Glycine max) seeds. Initially, variants of a type 1 DGAT from a high-oil, high-oleic acid plant seed, Corylus americana, were screened for high oil content in Saccharomyces cerevisiae. Nearly all DGAT variants examined from high-oil strains had increased affinity for oleoyl-CoA, with S0.5 values decreased as much as 4.7-fold compared with the wild-type value of 0.94 µm. Improved soybean DGAT variants were then designed to include amino acid substitutions observed in promising C. americana DGAT variants. The expression of soybean and C. americana DGAT variants in soybean somatic embryos resulted in oil contents as high as 10% and 12%, respectively, compared with only 5% and 7.6% oil achieved by overexpressing the corresponding wild-type DGATs. The affinity for oleoyl-CoA correlated strongly with oil content. The soybean DGAT variant that gave the greatest oil increase contained 14 amino acid substitutions out of a total of 504 (97% sequence identity with native). Seed-preferred expression of this soybean DGAT1 variant increased oil content of soybean seeds by an average of 3% (16% relative increase) in highly replicated, single-location field trials. The DGAT transgenes significantly reduced the soluble carbohydrate content of mature seeds and increased the seed protein content of some events. This study demonstrated that engineering of the native DGAT enzyme is an effective strategy to improve the oil content and value of soybeans. PMID:27208257

Carbon, oxygen and their interaction with intrinsic point defects in solar silicon ribbon material: A speculative approach

NASA Technical Reports Server (NTRS)

Goesele, U.; Ast, D. G.

1983-01-01

Some background information on intrinsic point defects is provided and on carbon and oxygen in silicon in so far as it may be relevant for the efficiency of solar cells fabricated from EFG ribbon material. The co-precipitation of carbon and oxygen and especially of carbon and silicon self interstitials are discussed. A simple model for the electrical activity of carbon-self-interstitial agglomerates is presented. The self-interstitial content of these agglomerates is assumed to determine their electrical activity and that both compressive stresses (high self-interstitial content) and tensile stresses (low self-interstitial content) give rise to electrical activity of the agglomerates. The self-interstitial content of these carbon-related agglomerates may be reduced by an appropriate high temperature treatment and enhanced by a supersaturation of self-interstitials generated during formation of the p-n junction of solar cells. Oxygen present in supersaturation in carbon-rich silicon may be induced to form SiO, precipitates by self-interstitials generated during phosphorus diffusion. It is proposed that the SiO2-Si interface of the precipates gives rise to a continuum of donor stables and that these interface states are responsible for at least part of the light inhancement effects observed in oxygen containing EFG silicon after phosphorus diffusion.

Comparison of ultrasound-assisted and traditional caustic leaching of spent cathode carbon (SCC) from aluminum electrolysis.

PubMed

Xiao, Jin; Yuan, Jie; Tian, Zhongliang; Yang, Kai; Yao, Zhen; Yu, Bailie; Zhang, Liuyun

2018-01-01

The spent cathode carbon (SCC) from aluminum electrolysis was subjected to caustic leaching to investigate the different effects of ultrasound-assisted and traditional methods on element fluorine (F) leaching rate and leaching residue carbon content. Sodium hydroxide (NaOH) dissolved in deionized water was used as the reaction system. Through single-factor experiments and a comparison of two leaching techniques, the optimum F leaching rate and residue carbon content for ultrasound-assisted leaching process were obtained at a temperature of 70°C, residue time of 40min, initial mass ratio of alkali to SCC (initial alkali-to-material ratio) of 0.6, liquid-to-solid ratio of 10mL/g, and ultrasonic power of 400W, respectively. Under the optimal conditions, the leaching residue carbon content was 94.72%, 2.19% larger than the carbon content of traditional leaching residue. Leaching wastewater was treated with calcium chloride (CaCl 2 ) and bleaching powder and the treated wastewater was recycled caustic solution. All in all, benefiting from advantage of the ultrasonication effects, ultrasound-assisted caustic leaching on spent cathode carbon had 55.6% shorter residue time than the traditional process with a higher impurity removal rate. Copyright © 2017 Elsevier B.V. All rights reserved.

Fractionated-combustion analysis of carbonate-containing phases in composite materials of the hydroxyapatite-calcium carbonate system

NASA Astrophysics Data System (ADS)

Goldberg, M. A.; Shibaeva, T. V.; Smirnov, V. V.; Kutsev, S. V.; Barinov, S. M.; Grigorovich, K. V.

2012-12-01

Materials in the hydroxyapatite (HA)-calcium carbonate (CC) system were synthesized by a precipitation method from aqueous solutions. According to the data of X-ray phase analysis and IR spectroscopy, the powders consisted of CC and AB-type carbonate-substituted HA (CHA). In order to determine the content of carbonate-containing phases in materials, the temperature-temporal mode of fractionated-combustion analysis of carbon was developed. The quantitative phase ratios and the degree of substitution of carbonate groups in CHA were determined. It was shown that the degree of substitution of carbonate groups in CHA increased from 2.47 to 5.31 wt % as the CC content increased from 13.50 to 88.33 wt %.

Soil carbon storage in a small arid catchment in the Negev desert (Israel)

NASA Astrophysics Data System (ADS)

Hoffmann, Ulrike; Kuhn, Nikolaus

2010-05-01

The mineral soil represents a major pool in the global carbon cycle. The behavior of mineral soil as a carbon reservoir in global climate and environmental issues is far from fully understood and causes a serious lack of comparable data on mineral soil organic carbon (SOC) at regional scale. To improve our understanding of soil carbon sequestration, it is necessary to acquire regional estimates of soil carbon pools in different ecosystem types. So far, little attention has been given to Dryland ecosystems, but they are often considered as highly sensitive to environmental change, with large and rapid responses to even smallest changes of climate conditions. Due to this fact, Drylands, as an ecosystem with extensive surface area across the globe (6.15 billion ha), have been suggested as a potential component for major carbon storage. A priori reasoning suggests that regional spatial patterns of SOC density (kg/m²) in Drylands are mostly affected by vegetation, soil texture, landscape position, soil truncation, wind erosion/deposition and the effect of water supply. Particularly unassigned is the interaction between soil volume, geomorphic processes and SOC density on regional scale. This study aims to enhance our understanding of regional spatial variability in dependence on soil volume, topography and surface parameters in areas susceptible to environmental change. Soil samples were taken in small transects at different representative slope positions across a range of elevations, soil texture, vegetation types, and terrain positions in a small catchment (600 ha) in the Negev desert. Topographic variables were extracted from a high resolution (0.5m) digital elevation model. Subsequently, we estimated the soil volume by excavating the entire soil at the representative sampling position. The volume was then estimated by laser scanning before and after soil excavation. SOC concentration of the soil samples was determined by CHN-analyser. For each sample, carbon densities (in kg/m²) were estimated for the mineral soil layer. The results indicate a large spatial variability of the carbon contents, the soil volume and depths across the landscape. In general, topography exerts a strong control on the carbon contents and the soil depths in the study site. Lowest carbon contents are apparent at the hillslope tops with increasing contents downslope. Because of the significantly larger carbon content at the northern exposed slope, we suggest that solar radiation driven differences of soil moisture content major controls SOC. Regarding the soil depths, the differences are not that clear. Soil depths seem to be higher at the southern exposed slope, but differences with respect to the slope position are not significant. Concerning the total amount of carbon storage in the study area, the results show that soil carbon may not be neglected in arid areas. Our results should provide an indication that carbon contents in dynamic environments are more affected and controlled by surface properties (soil volume) than by climate. Concluding that hint, climate is less important than surface processes in dryland ecosystems.

[Effects of different fertilization treatments on soil humic acid structure characteristics].

PubMed

Zhao, Nan; Lü, Yi-Zhong

2012-07-01

The present article used soil humic acid as research object to study effects on the structure characteristics of soil humic acid under the condition of applying cake fertilizer, green manure, straw fertilizer with the same contents of nitrogen and phosphorus. It used element analysis, micro infrared, and solid 13C-NMR for structure analysis, the results indicated that: The chemical composition and structure characteristics of humic acids were similar, but they also had many obvious differences. (1) The atomic ratios of H/C, O/C, and C/N were all different for the humic acids, the soil humic acid of cake fertilizer processing had the highest contents of H and N, green manure processing of soil humic acid contained the highest content of O, while straw fertilizer processing of soil humic acid contained highest content of C. (2) Infrared analysis displayed that the three soil humic acids contained protein Cake fertilizer processing of soil humic acid contained the most amino compounds, green manure processing of soil humic acid contained the maximum contents of hydroxyl and aliphatic hydrocarbon, while straw fertilizer processing of soil humic acid contained the highest contents of alcohol and phenol. (3) Solid 13C-NMR data indicated that cake fertilizer processing of soil humic acid contained the most carboxyl carbon, green manure processing of soil humic acid contained the highest contents of alkyl carbon and carbonyl carbon, while straw fertilizer processing of soil humic acids had the most alkoxy carbon and aromatic carbon

Re-evaluation of forest biomass carbon stocks and lessons from the world's most carbon-dense forests.

PubMed

Keith, Heather; Mackey, Brendan G; Lindenmayer, David B

2009-07-14

From analysis of published global site biomass data (n = 136) from primary forests, we discovered (i) the world's highest known total biomass carbon density (living plus dead) of 1,867 tonnes carbon per ha (average value from 13 sites) occurs in Australian temperate moist Eucalyptus regnans forests, and (ii) average values of the global site biomass data were higher for sampled temperate moist forests (n = 44) than for sampled tropical (n = 36) and boreal (n = 52) forests (n is number of sites per forest biome). Spatially averaged Intergovernmental Panel on Climate Change biome default values are lower than our average site values for temperate moist forests, because the temperate biome contains a diversity of forest ecosystem types that support a range of mature carbon stocks or have a long land-use history with reduced carbon stocks. We describe a framework for identifying forests important for carbon storage based on the factors that account for high biomass carbon densities, including (i) relatively cool temperatures and moderately high precipitation producing rates of fast growth but slow decomposition, and (ii) older forests that are often multiaged and multilayered and have experienced minimal human disturbance. Our results are relevant to negotiations under the United Nations Framework Convention on Climate Change regarding forest conservation, management, and restoration. Conserving forests with large stocks of biomass from deforestation and degradation avoids significant carbon emissions to the atmosphere, irrespective of the source country, and should be among allowable mitigation activities. Similarly, management that allows restoration of a forest's carbon sequestration potential also should be recognized.

Re-evaluation of forest biomass carbon stocks and lessons from the world's most carbon-dense forests

PubMed Central

Keith, Heather; Mackey, Brendan G.; Lindenmayer, David B.

2009-01-01

From analysis of published global site biomass data (n = 136) from primary forests, we discovered (i) the world's highest known total biomass carbon density (living plus dead) of 1,867 tonnes carbon per ha (average value from 13 sites) occurs in Australian temperate moist Eucalyptus regnans forests, and (ii) average values of the global site biomass data were higher for sampled temperate moist forests (n = 44) than for sampled tropical (n = 36) and boreal (n = 52) forests (n is number of sites per forest biome). Spatially averaged Intergovernmental Panel on Climate Change biome default values are lower than our average site values for temperate moist forests, because the temperate biome contains a diversity of forest ecosystem types that support a range of mature carbon stocks or have a long land-use history with reduced carbon stocks. We describe a framework for identifying forests important for carbon storage based on the factors that account for high biomass carbon densities, including (i) relatively cool temperatures and moderately high precipitation producing rates of fast growth but slow decomposition, and (ii) older forests that are often multiaged and multilayered and have experienced minimal human disturbance. Our results are relevant to negotiations under the United Nations Framework Convention on Climate Change regarding forest conservation, management, and restoration. Conserving forests with large stocks of biomass from deforestation and degradation avoids significant carbon emissions to the atmosphere, irrespective of the source country, and should be among allowable mitigation activities. Similarly, management that allows restoration of a forest's carbon sequestration potential also should be recognized. PMID:19553199

40 CFR 62.15205 - What minimum amount of monitoring data must I collect with my continuous emission monitoring...

Code of Federal Regulations, 2014 CFR

2014-07-01

... averages for sulfur dioxide, nitrogen oxides (Class I municipal waste combustion units only), and carbon monoxide are in parts per million by dry volume at 7 percent oxygen (or the equivalent carbon dioxide level). Use the 1-hour averages of oxygen (or carbon dioxide) data from your continuous emission monitoring...

40 CFR 62.15205 - What minimum amount of monitoring data must I collect with my continuous emission monitoring...

Code of Federal Regulations, 2013 CFR

2013-07-01

... averages for sulfur dioxide, nitrogen oxides (Class I municipal waste combustion units only), and carbon monoxide are in parts per million by dry volume at 7 percent oxygen (or the equivalent carbon dioxide level). Use the 1-hour averages of oxygen (or carbon dioxide) data from your continuous emission monitoring...

40 CFR 62.15205 - What minimum amount of monitoring data must I collect with my continuous emission monitoring...

Code of Federal Regulations, 2012 CFR

2012-07-01

... averages for sulfur dioxide, nitrogen oxides (Class I municipal waste combustion units only), and carbon monoxide are in parts per million by dry volume at 7 percent oxygen (or the equivalent carbon dioxide level). Use the 1-hour averages of oxygen (or carbon dioxide) data from your continuous emission monitoring...

ON MEASUREMENT OF CARBON CONTENT IN RETAINED AUSTENITE IN A NANOSTRUCTURED BAINITIC STEEL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garcia-Mateo, C.; Caballero, Francesca G.; Miller, Michael K

2012-01-01

In this study, the carbon content of retained austenite in a nanostructured bainitic steel was measured by atom probe tomography and compared with data derived from the austenite lattice parameter determined by X-ray diffraction. The results provide new evidence about the heterogeneous distribution of carbon in austenite, a fundamental issue controlling ductility in this type of microstructure.

Method and apparatus for selective removal of carbon monoxide

DOEpatents

Borup, Rodney L.; Skala, Glenn W.; Brundage, Mark A.; LaBarge, William J.

2000-01-01

There is provided a method and apparatus for treatment of a hydrogen-rich gas to reduce the carbon monoxide content thereof by reacting the carbon monoxide in the gas with an amount of oxygen sufficient to oxidize at least a portion of the carbon monoxide in the presence of a catalyst in a desired temperature range without substantial reaction of hydrogen. The catalyst is an iridium-based catalyst dispersed on, and supported on, a carrier. In the presence of the catalyst, carbon monoxide in a hydrogen-rich feed gas is selectively oxidized such that a product stream is produced with a very low carbon monoxide content.

Microstructures and Hardness/Wear Performance of High-Carbon Stellite Alloys Containing Molybdenum

NASA Astrophysics Data System (ADS)

Liu, Rong; Yao, J. H.; Zhang, Q. L.; Yao, M. X.; Collier, Rachel

2015-12-01

Conventional high-carbon Stellite alloys contain a certain amount of tungsten which mainly serves to provide strengthening to the solid solution matrix. These alloys are designed for combating severe wear. High-carbon molybdenum-containing Stellite alloys are newly developed 700 series of Stellite family, with molybdenum replacing tungsten, which are particularly employed in severe wear condition with corrosion also involved. Three high-carbon Stellite alloys, designated as Stellite 706, Stellite 712, and Stellite 720, with different carbon and molybdenum contents, are studied experimentally in this research, focusing on microstructure and phases, hardness, and wear resistance, using SEM/EDX/XRD techniques, a Rockwell hardness tester, and a pin-on-disk tribometer. It is found that both carbon and molybdenum contents influence the microstructures of these alloys significantly. The former determines the volume fraction of carbides in the alloys, and the latter governs the amount of molybdenum-rich carbides precipitated in the alloys. The hardness and wear resistance of these alloys are increased with the carbide volume fraction. However, with the same or similar carbon content, high-carbon CoCrMo Stellite alloys exhibit worse wear resistance than high-carbon CoCrW Stellite alloys.

Comparison and evaluation of in situ and filter carbon measurements at the Fresno Supersite

NASA Astrophysics Data System (ADS)

Watson, John G.; Chow, Judith C.

2002-11-01

The Fresno Supersite in Fresno, California, USA, acquires in situ 5- to 60-min average PM2.5 organic carbon (OC), elemental carbon (EC), and total carbon (TC) measurements by the following methods: (1) thermal evolution carbon analyzer for organic, elemental, and total carbon; (2) single-wavelength and seven-color aethalometer for black carbon (BC); and (3) photoionization for particle-bound polycyclic aromatic hydrocarbons. Twenty-four-hour average PM2.5 filter-based measurements include (1) nondenuded quartz filters with no backup filter in a PM2.5 Federal Reference Method (FRM) sampler; (2) quartz filters behind an organic carbon denuder with a quartz backup filter in a Reference Ambient Aerosol Sampler (RAAS); (3) nondenuded quartz filters with backup filter in a RAAS; and (4) nondenuded quartz filters with no backup filter in a sequential filter sampler. Filter samples are analyzed after sampling by the Interagency Monitoring of Protected Visual Environments (IMPROVE) thermal/optical reflectance carbon analysis protocol. Collocated measurements are examined for year 2000. Measurement equivalence is found for PM2.5 mass, light transmission, and TC between the FRM and RAAS speciation samplers. The average ratios of front filter carbon between the denuded and nondenuded channels in the RAAS sampler are 0.83 ± 0.19 for TC, 0.81 ± 0.20 for OC, and 1.01 ± 0.33 for EC. The average differences for TC and OC are low (1.2 to 1.4 μg m-3) and are comparable to the measurement uncertainties. Continuous thermal evolution carbon measurements are not comparable to filter measurements. Aethalometer BC and filter EC are highly correlated, but filter EC is consistently 20-25% higher than continuous aethalometer BC. Pairwise comparisons show filter EC measurements acquired in this study are predictable from aethalometer BC measurements.

Investigations on soil organic carbon stocks and active layer thickness in West Greenland

NASA Astrophysics Data System (ADS)

Gries, Philipp; Wagner, Julia; Kandolf, Lorenz; Henkner, Jessica; Kühn, Peter; Scholten, Thomas; Schmidt, Karsten

2017-04-01

The soil organic carbon (SOC) pool in the first 300 cm of arctic soils includes about 50 % of the estimated global terrestrial belowground organic carbon, which makes about 1024 Pg C and up to 496 Pg within the upper permafrost one meter. Being a sensible ecosystem, the Arctic is sensitive to climate change. Hence, thawing of permafrost-affected soils to greater depth and for longer periods increases the release of CO2 and CH4 to the atmosphere, which queries soils as an important carbon pool. Especially in arctic environments, sparse soil data and limited knowledge of soil processes cause underestimation of SOC stocks. Due to different regional climatic conditions, changing soil-environmental conditions result in varying soil organic carbon contents in Greenland. In West Greenland, coastal oceanic conditions turn into continental climate at the ice margin showing less precipitation, higher insolation and increasing permafrost thickness. The objectives of this study are (i) to determine SOC stocks and active layer thickness (ALT), (ii) to identify main environmental factors influencing SOC stocks and ALT, and (iii) to specify differences of SOC stocks, ALT and influencing factors induced by a climatic trend in West Greenland. Respecting different climatic conditions, one study area is situated next to the ice margin in the Kangerlussuaq area and the second one is located near Sisimiut at the coast. Both study areas (2 km2) are representative for each region and have similar environmental settings. Soil samples were taken from depth increments (0-25, 25-50, 50-100, and 100-200 cm) at 80 sampling locations in each study area. Additionally, we addressed soil moisture content (TDR-measurements), ALT, and soil horizons, vegetation (types, coverage), and terrain characteristics (aspect, geomorphology) at each sampling point. As a preliminary result, at the coast the average SOC stock is 13.1 kg/m2 in the upper 25 cm and about 35.9 kg/m2 in the first 200 cm. The amount of SOC stocks is slightly connected to terrain with higher values at depressions and decreasing values upslope. We assume for the Sisimiut area that south (SE, S, SW) facing areas have high SOC stocks due to higher biomass production because of higher insolation. In both study areas, plant growth, aspect, and soil moisture affect the amount of ALT, which is low beneath dense and tall dwarf shrub vegetation on flat plains and depressions having high soil moisture contents. At north facing slopes, absence of direct insolation results in low ALT less than 14 cm at the Kangerlussuaq study area. Soil moisture content, ALT and occurrence of permafrost as well as vegetation type and coverage reflect the climatic trend from the coast to the ice margin in West Greenland.

A new carbon-rich phase (COPS) in Antarctic micrometeorites

NASA Technical Reports Server (NTRS)

Engrand, C.; Maurette, M.; Kurat, G.; Brandstatter, F.; Perreau, M.

1993-01-01

The contemporary flux of micrometeorites with sizes greater than 50 microns reaching the Earth's surface each year (about 20,000 tons/a) is much greater than the value of approximately 100 tons/a reported for conventional meteorites up to masses of approximately 10,000 tons. Moreover, on the average, Antarctic micrometeorites contain at least as much carbon as does Orgueil, the most C-rich meteorite. Micrometeorites are thus responsible for most of the carbon accreted by the Earth. In this paper we report SEM observations of a new C-rich 'dirty magnetite' phase observed as tiny inclusions in both melted and unmelted micrometeorites. This phase, which is enriched in C, O, P, S, Fe, frequently shows Ni contents in excess of 0.2 percent, strongly suggestive of an 'extraterrestrial' origin. We also discovered this 'COPS' phase in the fusion crust of Murchison. It appears likely that COPS is a product of meteoroid reprocessing during frictional heating in the Earth's atmosphere and/or its fast 'weathering' in the upper atmosphere. Upon 'catalyzed' hydrolysis this phase might have facilitated the functioning of micrometeorites as 'micro-chondritic-reactors' for the synthesis of prebiotic molecules on the early Earth.

Prediction of Soil Organic Carbon at the European Scale by Visible and Near InfraRed Reflectance Spectroscopy.

PubMed

Stevens, Antoine; Nocita, Marco; Tóth, Gergely; Montanarella, Luca; van Wesemael, Bas

2013-01-01

Soil organic carbon is a key soil property related to soil fertility, aggregate stability and the exchange of CO2 with the atmosphere. Existing soil maps and inventories can rarely be used to monitor the state and evolution in soil organic carbon content due to their poor spatial resolution, lack of consistency and high updating costs. Visible and Near Infrared diffuse reflectance spectroscopy is an alternative method to provide cheap and high-density soil data. However, there are still some uncertainties on its capacity to produce reliable predictions for areas characterized by large soil diversity. Using a large-scale EU soil survey of about 20,000 samples and covering 23 countries, we assessed the performance of reflectance spectroscopy for the prediction of soil organic carbon content. The best calibrations achieved a root mean square error ranging from 4 to 15 g C kg(-1) for mineral soils and a root mean square error of 50 g C kg(-1) for organic soil materials. Model errors are shown to be related to the levels of soil organic carbon and variations in other soil properties such as sand and clay content. Although errors are ∼5 times larger than the reproducibility error of the laboratory method, reflectance spectroscopy provides unbiased predictions of the soil organic carbon content. Such estimates could be used for assessing the mean soil organic carbon content of large geographical entities or countries. This study is a first step towards providing uniform continental-scale spectroscopic estimations of soil organic carbon, meeting an increasing demand for information on the state of the soil that can be used in biogeochemical models and the monitoring of soil degradation.

Prediction of Soil Organic Carbon at the European Scale by Visible and Near InfraRed Reflectance Spectroscopy

PubMed Central

Stevens, Antoine; Nocita, Marco; Tóth, Gergely; Montanarella, Luca; van Wesemael, Bas

2013-01-01

Soil organic carbon is a key soil property related to soil fertility, aggregate stability and the exchange of CO2 with the atmosphere. Existing soil maps and inventories can rarely be used to monitor the state and evolution in soil organic carbon content due to their poor spatial resolution, lack of consistency and high updating costs. Visible and Near Infrared diffuse reflectance spectroscopy is an alternative method to provide cheap and high-density soil data. However, there are still some uncertainties on its capacity to produce reliable predictions for areas characterized by large soil diversity. Using a large-scale EU soil survey of about 20,000 samples and covering 23 countries, we assessed the performance of reflectance spectroscopy for the prediction of soil organic carbon content. The best calibrations achieved a root mean square error ranging from 4 to 15 g C kg−1 for mineral soils and a root mean square error of 50 g C kg−1 for organic soil materials. Model errors are shown to be related to the levels of soil organic carbon and variations in other soil properties such as sand and clay content. Although errors are ∼5 times larger than the reproducibility error of the laboratory method, reflectance spectroscopy provides unbiased predictions of the soil organic carbon content. Such estimates could be used for assessing the mean soil organic carbon content of large geographical entities or countries. This study is a first step towards providing uniform continental-scale spectroscopic estimations of soil organic carbon, meeting an increasing demand for information on the state of the soil that can be used in biogeochemical models and the monitoring of soil degradation. PMID:23840459

[Distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta].

PubMed

Dong, Hong-Fang; Yu, Jun-Bao; Guan, Bo

2013-01-01

Applying the method of physical fractionation, distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta were studied. The results showed that the heavy fraction organic carbon was the dominant component of soil organic carbon in the studied region. There was a significantly positive relationship between the content of heavy fraction organic carbon, particulate organic carbon and total soil organic carbon. The ranges of soil light fraction organic carbon ratio and content were 0.008% - 0.15% and 0.10-0.40 g x kg(-1), respectively, and the range of particulate organic carbon ratio was 8.83% - 30.58%, indicating that the non-protection component of soil organic carbon was low and the carbon pool was relatively stable in Suaeda salsa wetland of the Yellow River delta.

Microbial biomass carbon and enzyme activities of urban soils in Beijing.

PubMed

Wang, Meie; Markert, Bernd; Shen, Wenming; Chen, Weiping; Peng, Chi; Ouyang, Zhiyun

2011-07-01

To promote rational and sustainable use of soil resources and to maintain the urban soil quality, it is essential to assess urban ecosystem health. In this study, the microbiological properties of urban soils in Beijing and their spatial distribution patterns across the city were evaluated based on measurements of microbial biomass carbon and urease and invertase activities of the soils for the purpose of assessing the urban ecosystem health of Beijing. Grid sampling design, normal Kriging technique, and the multiple comparisons among different land use types were used in soil sampling and data treatment. The inherent chemical characteristics of urban soils in Beijing, e.g., soil pH, electronic conductivity, heavy metal contents, total N, P and K contents, and soil organic matter contents were detected. The size and diversity of microbial community and the extent of microbial activity in Beijing urban soils were measured as the microbial biomass carbon content and the ratio of microbial biomass carbon content to total soil organic carbon. The microbial community health measured in terms of microbial biomass carbon, urease, and invertase activities varied with the organic substrate and nutrient contents of the soils and were not adversely affected by the presence of heavy metals at p < 0.01. It was shown that the older and the biologically more stable part of city exhibited higher microbial activity levels than the more recently developed part of the city and the road areas of heavy traffic. It was concluded that the land use patterns in Beijing urban soils influenced the nature and activities of the microbial communities.

Coal char oxidation kinetics in air medium

NASA Astrophysics Data System (ADS)

Slyusarskiy, K. V.; Jankovskiy, S. A.; Korotkikh, A. G.; Sorokin, I. V.

2017-01-01

Research on oxidation in air medium process of three different coal chars with various carbon content was presented. The anthracite, T-grade bituminous coal and 2B-grade lignite char powders with particle size less than 80 µm were studied. The coal char oxidation was studied by isothermal method using coupled TG-DSC analyzer Netzsch STA 449 Jupiter F3 in the temperature range 1000-1200 °C. Experiments were carried out at ambient pressure. Volumetric flow rate of oxidation medium into analyzer chamber was 250 ml/min and consisted of oxygen and argon with volumetric ratio 24:1. Based on experimental data, the average rate of carbon oxidation reaction values were defined at each temperature. Kinetic constants (frequency factor and activation energy) of reaction were defined as well via 1st order Arrhenius equation. Activation energy values are in good agreement with the data presented in the literature. Activation energy values for anthracite char are 1.6-1.7 times higher than those for bituminous coal and lignite chars, respectively.

A facile self-assembly approach to prepare palladium/carbon nanotubes catalyst for the electro-oxidation of ethanol

NASA Astrophysics Data System (ADS)

Wen, Cuilian; Zhang, Xinyuan; Wei, Ying; Zhang, Teng; Chen, Changxin

2018-02-01

A facile self-assembly approach is reported to prepare palladium/carbon nanotubes (Pd/CNTs) catalyst for the electro-oxidation of ethanol. In this method, the Pd-oleate/CNTs was decomposed into the Pd/CNTs at an optimal temperature of 195 °C in air, in which no inert gas is needed for the thermal decomposition process due to the low temperature used and the decomposed products are also environmental friendly. The prepared Pd/CNTs catalyst has a high metallic Pd0 content and the Pd particles in the catalyst are disperse, uniform-sized with an average size of ˜2.1 nm, and evenly distributed on the CNTs. By employing our strategy, the problems including the exfoliation of the metal particles from the CNTs and the aggregation of the metal particles can be solved. Comparing with the commercial Pd/C one, the prepared Pd/CNTs catalyst exhibits a much higher electrochemical activity and stability for the electro-oxidation of ethanol in the direct ethanol fuel cells.

Geochemistry of impact glasses from the K/T boundary in Haiti - Relation to smectites and a new type of glass

NASA Technical Reports Server (NTRS)

Koeberl, Christian; Sigurdsson, Haraldur

1992-01-01

Detailed element analyses were carried out on 12 black and seven yellow glasses from the K/T boundary section at Beloc (Haiti), and of three samples from smectite mantles around black glasses. The results obtained for bulk black and yellow glasses show differences between these, confirming the results of Sigurdsson et al. (1991) and Izett (1991), and the results obtained on individual spherules and shards are in agreement with bulk data. The present data also demonstrate, for the first time, the existence of yellow glass samples with high CaO but low S contents, which might have formed by fusion of various proportions of carbonates and evaporites or carbonates alone. One of the black glasses was found to have higher than average SiO2 and K2O abundances but lower concentrations of all other major elements. This suggests the existence of a third glass type, named the high Si-K variety (HSi,K) glass.

Nanocrystalline ordered vanadium carbide: Superlattice and nanostructure

NASA Astrophysics Data System (ADS)

Kurlov, A. S.; Gusev, A. I.; Gerasimov, E. Yu.; Bobrikov, I. A.; Balagurov, A. M.; Rempel, A. A.

2016-02-01

The crystal structure, micro- and nanostructure of coarse- and nanocrystalline powders of ordered vanadium carbide V8C7 have been examined by X-ray and neutron diffraction and electron microscopy methods. The synthesized coarse-crystalline powder of ordered vanadium carbide has flower-like morphology. It was established that the real ordered phase has the composition V8C7-δ (δ ≅ 0.03) deviating from perfect stoichiometric composition V8C7. The vanadium atoms forming the octahedral environment □V6 of vacant sites in V8C7-δ are displaced towards the vacancy □. The presence of carbon onion-like structures was found in the vanadium carbide powders with a small content of free (uncombined) carbon. The nanopowders of V8C7-δ carbide with average particle size of 20-30 nm produced by high-energy milling of coarse-crystalline powder retain the crystal structure of the initial powder, but differ in the lattice deformation distortion anisotropy.

Erratum: Retraction Note to: Effect of Carbon Content on the Electrical Conductivity of Carbon Black-Filled PMC with Various Matrices

NASA Astrophysics Data System (ADS)

Shin, Soon-Gi

2018-03-01

The Editor-in-Chief and Editorial Board of Electronic Materials Letters have retracted this article [1] because its contents have been previously published by Miyasaka et al. [2]. The contents of this article are therefore redundant. Author Soon-Gi Shin has not responded to correspondence from the Editor about this retraction.

[Effects of combined application of biochar and inorganic fertilizers on the available phosphorus content of upland red soil].

PubMed

Jing, Yan; Chen, Xiao-min; Liu, Zu-xiang; Huang, Qian-ru; LiI, Qiu-xia; Chen, Chen; Lu, Shao-shan

2013-04-01

Aiming at the low content of available phosphorus in upland red soil of Southern China, this paper studied the effects of combined application of biochar and inorganic fertilizers on the available phosphorus and organic carbon contents and the pH of this soil. With the combined application of biochar and inorganic fertilizers, the soil physical and chemical properties improved to different degrees. As compared with the control, the soil pH and the soil organic carbon and available phosphorus contents at different growth stages of oil rape after the combined application of biochar and inorganic fertilizers all had an improvement, with the increments at bolting stage, flowering stage, and ripening stage being 16%, 24% and 26%, 23%, 34% and 38%, and 100%, 191% and 317% , respectively. The soil pH and the soil organic carbon and available phosphorus contents were increased with the increasing amount of applied biochar. Under-the application of biochar, the soil available phosphorus had a significant correlation with the soil pH and soil organic carbon content. This study could provide scientific basis to improve the phosphorus deficiency and the physical and chemical properties of upland red soil.

The pore structure and fractal characteristics of shales with low thermal maturity from the Yuqia Coalfield, northern Qaidam Basin, northwestern China

NASA Astrophysics Data System (ADS)

Hou, Haihai; Shao, Longyi; Li, Yonghong; Li, Zhen; Zhang, Wenlong; Wen, Huaijun

2018-03-01

The continental shales from the Middle Jurassic Shimengou Formation of the northern Qaidam Basin, northwestern China, have been investigated in recent years because of their shale gas potential. In this study, a total of twenty-two shale samples were collected from the YQ-1 borehole in the Yuqia Coalfield, northern Qaidam Basin. The total organic carbon (TOC) contents, pore structure parameters, and fractal characteristics of the samples were investigated using TOC analysis, low-temperature nitrogen adsorption experiments, and fractal analysis. The results show that the average pore size of the Shimengou shales varied from 8.149 nm to 20.635 nm with a mean value of 10.74 nm, which is considered mesopore-sized. The pores of the shales are mainly inkbottle- and slit-shaped. The sedimentary environment plays an essential role in controlling the TOC contents of the low maturity shales, with the TOC values of shales from deep to semi-deep lake facies (mean: 5.23%) being notably higher than those of the shore-shallow lake facies (mean: 0.65%). The fractal dimensions range from 2.4639 to 2.6857 with a mean of 2.6122, higher than those of marine shales, which indicates that the pore surface was rougher and the pore structure more complex in these continental shales. The fractal dimensions increase with increasing total pore volume and total specific surface area, and with decreasing average pore size. With increasing TOC contents in shales, the fractal dimensions increase first and then decrease, with the highest value occurring at 2% of TOC content, which is in accordance with the trends between the TOC and both total specific surface area and total pore volume. The pore structure complexity and pore surface roughness of these low-maturity shales would be controlled by the combined effects of both sedimentary environments and the TOC contents.

Martensite phase stress and the strengthening mechanism in TRIP steel by neutron diffraction.

PubMed

Harjo, Stefanus; Tsuchida, Noriyuki; Abe, Jun; Gong, Wu

2017-11-09

Two TRIP-aided multiphase steels with different carbon contents (0.2 and 0.4 mass%) were analyzed in situ during tensile deformation by time-of-flight neutron diffraction to clarify the deformation induced martensitic transformation behavior and its role on the strengthening mechanism. The difference in the carbon content affected mainly the difference in the phase fractions before deformation, where the higher carbon content increased the phase fraction of retained austenite (γ). However, the changes in the relative fraction of martensitic transformation with respect to the applied strain were found to be similar in both steels since the carbon concentrations in γ were similar regardless of different carbon contents. The phase stress of martensite was found much larger than that of γ or bainitic ferrite since the martensite was generated at the beginning of plastic deformation. Stress contributions to the flow stress were evaluated by multiplying the phase stresses and their phase fractions. The stress contribution from martensite was observed increasing during plastic deformation while that from bainitic ferrite hardly changing and that from γ decreasing.

Reduction of carbon content in waste-tire combustion ashes by bio-thermal treatment.

PubMed

Chen, Chun-Chi; Lee, Wen-Jhy; Shih, Shun-I; Mou, Jin-Luh

2009-11-01

Application of bio-catalyst (NOE-7F) in thermal treatment can adequately dispose dark-black fly ashes from co-combustion of both waste tires and coal. After thermal treatment of fly ashes by adding 10% NOE-7F, the carbon contents reduced by 37.6% and the weight losses increased by 405%, compared with the fly ashes without mixing with NOE-7F. The combustion behaviors of wasted tires combustion fly ashes with NOE-7F were also investigated by both thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The results verify that NOE-7F has positive effects on the combustion of residual carbon and toxic polycyclic aromatic hydrocarbons (PAHs) enhance the energy release and reduce the toxicity during the process of thermal treatment. Furthermore, using NOE-7F to dispose high-carbon content fly ashes did improve the compressive strength of fly ashes and concrete mixtures. Therefore, NOE-7F is a promising additive which could decrease treatment cost of high-carbon content fly ashes and reduce the amount of survival toxic PAHs.

Reduction of carbon content in waste-tire combustion ashes by bio-thermal treatment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, C.C.; Lee, W.J.; Shih, S.I.

2009-07-01

Application of bio-catalyst (NOE-7F) in thermal treatment can adequately dispose dark-black fly ashes from co-combustion of both waste tires and coal. After thermal treatment of fly ashes by adding 10% NOE-7F, the carbon contents reduced by 37.6% and the weight losses increased by 405%, compared with the fly ashes without mixing with NOE-7F. The combustion behaviors of wasted tires combustion fly ashes with NOE-7F were also investigated by both thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The results verify that NOE-7F has positive effects on the combustion of residual carbon and toxic polycyclic aromatic hydrocarbons (PAHs) enhance the energymore » release and reduce the toxicity during the process of thermal treatment. Furthermore, using NOE-7F to dispose high-carbon content fly ashes did improve the compressive strength of fly ashes and concrete mixtures. Therefore, NOE-7F is a promising additive which could decrease treatment cost of high-carbon content fly ashes and reduce the amount of survival toxic PAHs.« less

Method for creating high carbon content products from biomass oil

DOEpatents

Parker, Reginald; Seames, Wayne

2012-12-18

In a method for producing high carbon content products from biomass, a biomass oil is added to a cracking reactor vessel. The biomass oil is heated to a temperature ranging from about 100.degree. C. to about 800.degree. C. at a pressure ranging from about vacuum conditions to about 20,700 kPa for a time sufficient to crack the biomass oil. Tar is separated from the cracked biomass oil. The tar is heated to a temperature ranging from about 200.degree. C. to about 1500.degree. C. at a pressure ranging from about vacuum conditions to about 20,700 kPa for a time sufficient to reduce the tar to a high carbon content product containing at least about 50% carbon by weight.

Recycling of coal combustion wastes.

PubMed

Oz, Derya; Koca, Sabina; Koca, Huseyin

2009-05-01

The separation of unburned carbon from coal-fired power plant bottom ashes was conducted in order to increase the possibility of the recycling of coal combustion wastes. A two-stage flotation technique was used for this study. In the rougher flotation experiments the amounts of collector, dispersant and frother, pulp density, pH, particle size distribution, flotation time and flotation temperature were tested as variables. After rougher flotation experiments, at optimum conditions, the carbon content of the concentrate increased from 13.85 to 51.54% at a carbon recovery of 54.54%. Under the same conditions, the carbon content was reduced to 4.54% at a weight yield of over 80% in the tailings fraction. This fraction meets the industrial specifications and can be utilized as a cement additive. After the cleaner flotation experiment the carbon content of the product was enhanced to 64.81% with a 52.16% carbon recovery. This fraction can be blended back into the coal feed to the power plant boilers.

Vertical transport of carbon-14 into deep-sea food webs

NASA Astrophysics Data System (ADS)

Pearcy, W. G.; Stuiver, Minze

1983-04-01

During the years 1973 to 1976 the carbon-14 content was higher in epipelagic and vertically migrating, upper mesopelagic animals (caught between 0 and 500 m) than in lower mesopelagic, bathypelagic, and abyssobenthic animals (500 to 5180 m) in the northeastern Pacific Ocean. Only one species of deep-sea fish had a Δ14C value as high as surface-caught fish. The 14C content of most animals was higher pre-bomb levels, but the relatively low 14C content of most deep-sea animals indicates that the majority of their carbon was not derived directly from a near-surface food chain labeled with bomb carbon. A mean residence time of about 35 y was estimated for the organic carbon pool for abyssobenthic animals based on the relative increase of radiocarbon in surface-dwelling animals since 1967. The results suggest that rapidly sinking particles from surface waters, such as fecal pellets, are not the major source of organic carbon for deep-sea fishes and large benthic invertebrates.

Synthesis of a Carbon-activated Microfiber from Spider Webs Silk

NASA Astrophysics Data System (ADS)

Taer, E.; Mustika, W. S.; Taslim, R.

2017-03-01

Carbon fiber of spider web silk has been produced through the simple carbonization process. Cobwebs are a source of strong natural fiber, flexible and micrometer in size. Preparation of micro carbon fiber from spider webs that consist of carbonization and activation processes. Carbonization was performed in N2 gas environment by multi step heating profile up to temperature of 400 °C, while the activation process was done by using chemical activation with KOH activating agent assistance. Measurement of physical properties was conducted on the surface morphology, element content and the degree of crystallinity. The measurement results found that micro carbon fiber from spider webs has a diameter in the range of 0.5 -25 micrometers. It is found that the carbon-activated microfiber takes the amorphous form with the carbon content of 84 %.

The effects of the structure characteristics on Magnetic Barkhausen noise in commercial steels

NASA Astrophysics Data System (ADS)

Deng, Yu; Li, Zhe; Chen, Juan; Qi, Xin

2018-04-01

This study has been done by separately measuring Magnetic Barkhausen noise (MBN) under different structure characteristics, namely the carbon content, hardness, roughness, and elastic modulus in commercial steels. The result of the experiments shows a strong dependence of MBN parameters (peak height, Root mean square (RMS), and average value) on structure characteristics. These effects, according to this study, can be explained by two kinds of source mechanisms of the MBN, domain wall nucleation and wall propagation. The discovery obtained in this paper can provide basic knowledge to understand the existing surface condition problem of Magnetic Barkhausen noise as a non-destructive evaluation technique and bring MBN into wider application.

Autocorrelation analysis of the infrared spectra of synthetic and biogenic carbonates along the calcite-dolomite join

NASA Astrophysics Data System (ADS)

Jenkins, David M.; Holmes, Zachary F.; Ishida, Kiyotaka; Manuel, Phillip D.

2018-01-01

Autocorrelation analysis of infrared spectra can provide insights on the strain energy associated with cation substitutions along a solid-solution compositional join which to date has been applied primarily to silicate minerals. In this study, the method is applied to carbonates synthesized at 10 mol% increments along the calcite-dolomite (CaCO3-CaMg(CO3)2) join in the range of 1000-1150 °C and 0.6-2.5 GPa for the purpose of determining how the band broadening in both the far- and mid-infrared ranges, as represented by the autocorrelation parameter δΔCorr, compares with the existing enthalpy of mixing data for this join. It was found that the carbonate internal vibration ν2 (out-of-plane bending) in the mid-infrared range, and the sum of the three internal vibration modes ν4 + ν2 + ν3 most closely matched the enthalpy of mixing data for the synthetic carbonates. Autocorrelation analysis of a series of biogenic carbonates in the mid-infrared range showed only a systematic variation for the ν2 band. Using the biogenic carbonate with the lowest Mg content for reference, the trend in δΔCorr for biogenic carbonates shows a steady increase with increasing Mg content suggesting a steady increase in solubility with Mg content. The results from this study indicate that autocorrelation analysis of carbonates in the mid-infrared range provides an independent and reliable assessment of the crystallographic strain energy of carbonates. In particular, inorganic carbonates in the range of 0-17 mol% MgCO3 experience a minimum in strain energy and a corresponding minimum in the enthalpy of mixing, whereas biogenic carbonates show a steady increase in strain energy with increasing MgCO3 content. In the event of increasing ocean acidification, biogenic carbonates in the range of 0-17 mol% MgCO3 will dissolve more readily than the compositionally equivalent inorganic carbonates.

Preservation of overmature, ancient, sedimentary organic matter in carbonate concretions during outcrop weathering.

PubMed

Loyd, S J

2017-01-01

Concretions are preferentially cemented zones within sediments and sedimentary rocks. Cementation can result from relatively early diagenetic processes that include degradation of sedimentary organic compounds or methane as indicated by significantly 13 C-depleted or enriched carbon isotope compositions. As minerals fill pore space, reduced permeability may promote preservation of sediment components from degradation during subsequent diagenesis, burial heating and outcrop weathering. Discrete and macroscopic organic remains, macro and microfossils, magnetic grains, and sedimentary structures can be preferentially preserved within concretions. Here, Cretaceous carbonate concretions of the Holz Shale are shown to contain relatively high carbonate-free total organic carbon (TOC) contents (up to ~18.5 wt%) compared to the surrounding host rock (with <2.1 wt%). TOC increases with total inorganic carbon (TIC) content, a metric of the degree of cementation. Pyrite contents within concretions generally correlate with organic carbon contents. Concretion carbonate carbon isotope compositions (δ 13 C carb ) range from -22.5 to -3.4‰ (VPDB) and do not correlate strongly with TOC. Organic carbon isotope compositions (δ 13 C org ) of concretions and host rock are similar. Thermal maturity data indicate that both host and concretion organic matter are overmature and have evolved beyond the oil window maturity stage. Although the organic matter in general has experienced significant oxidative weathering, concretion interiors exhibit lower oxygen indices relative to the host. These results suggest that carbonate concretions can preferentially preserve overmature, ancient, sedimentary organic matter during outcrop weathering, despite evidence for organic matter degradation genetic mechanisms. As a result, concretions may provide an optimal proxy target for characterization of more primary organic carbon concentrations and chemical compositions. In addition, these findings indicate that concretions can promote delayed oxidative weathering of organic carbon in outcrop and therefore impact local chemical cycling. © 2016 John Wiley & Sons Ltd.

Autocorrelation analysis of the infrared spectra of synthetic and biogenic carbonates along the calcite-dolomite join

NASA Astrophysics Data System (ADS)

Jenkins, David M.; Holmes, Zachary F.; Ishida, Kiyotaka; Manuel, Phillip D.

2018-06-01

Autocorrelation analysis of infrared spectra can provide insights on the strain energy associated with cation substitutions along a solid-solution compositional join which to date has been applied primarily to silicate minerals. In this study, the method is applied to carbonates synthesized at 10 mol% increments along the calcite-dolomite (CaCO3-CaMg(CO3)2) join in the range of 1000-1150 °C and 0.6-2.5 GPa for the purpose of determining how the band broadening in both the far- and mid-infrared ranges, as represented by the autocorrelation parameter δΔCorr, compares with the existing enthalpy of mixing data for this join. It was found that the carbonate internal vibration ν2 (out-of-plane bending) in the mid-infrared range, and the sum of the three internal vibration modes ν4 + ν2 + ν3 most closely matched the enthalpy of mixing data for the synthetic carbonates. Autocorrelation analysis of a series of biogenic carbonates in the mid-infrared range showed only a systematic variation for the ν2 band. Using the biogenic carbonate with the lowest Mg content for reference, the trend in δΔCorr for biogenic carbonates shows a steady increase with increasing Mg content suggesting a steady increase in solubility with Mg content. The results from this study indicate that autocorrelation analysis of carbonates in the mid-infrared range provides an independent and reliable assessment of the crystallographic strain energy of carbonates. In particular, inorganic carbonates in the range of 0-17 mol% MgCO3 experience a minimum in strain energy and a corresponding minimum in the enthalpy of mixing, whereas biogenic carbonates show a steady increase in strain energy with increasing MgCO3 content. In the event of increasing ocean acidification, biogenic carbonates in the range of 0-17 mol% MgCO3 will dissolve more readily than the compositionally equivalent inorganic carbonates.

Timescales of carbon turnover in soils with mixed crystalline mineralogies

NASA Astrophysics Data System (ADS)

Khomo, Lesego; Trumbore, Susan; Bern, Carleton R.; Chadwick, Oliver A.

2017-01-01

Organic matter-mineral associations stabilize much of the carbon (C) stored globally in soils. Metastable short-range-order (SRO) minerals such as allophane and ferrihydrite provide one mechanism for long-term stabilization of organic matter in young soil. However, in soils with few SRO minerals and a predominance of crystalline aluminosilicate or Fe (and Al) oxyhydroxide, C turnover should be governed by chemisorption with those minerals. Here, we correlate mineral composition from soils containing small amounts of SRO minerals with mean turnover time (TT) of C estimated from radiocarbon (14C) in bulk soil, free light fraction and mineral-associated organic matter. We varied the mineral amount and composition by sampling ancient soils formed on different lithologies in arid to subhumid climates in Kruger National Park (KNP), South Africa. Mineral contents in bulk soils were assessed using chemical extractions to quantify Fe oxyhydroxides and SRO minerals. Because of our interest in the role of silicate clay mineralogy, particularly smectite (2 : 1) and kaolinite (1 : 1), we separately quantified the mineralogy of the clay-sized fraction using X-ray diffraction (XRD) and measured 14C on the same fraction. Density separation demonstrated that mineral associated C accounted for 40-70 % of bulk soil organic C in A and B1 horizons for granite, nephelinite and arid-zone gabbro soils, and > 80 % in other soils. Organic matter strongly associated with the isolated clay-sized fraction represented only 9-47 % of the bulk soil C. The mean TT of C strongly associated with the clay-sized fraction increased with the amount of smectite (2 : 1 clays); in samples with > 40 % smectite it averaged 1020 ± 460 years. The C not strongly associated with clay-sized minerals, including a combination of low-density C, the C associated with minerals of sizes between 2 µm and 2 cm (including Fe oxyhydroxides as coatings), and C removed from clay-sized material by 2 % hydrogen peroxide had TTs averaging 190 ± 190 years in surface horizons. Summed over the bulk soil profile, we found that smectite content correlated with the mean TT of bulk soil C across varied lithologies. The SRO mineral content in KNP soils was generally very low, except for the soils developed on gabbros under more humid climate that also had very high Fe and C contents with a surprisingly short, mean C TTs. In younger landscapes, SRO minerals are metastable and sequester C for long timescales. We hypothesize that in the KNP, SRO minerals represent a transient stage of mineral evolution and therefore lock up C for a shorter time. Overall, we found crystalline Fe-oxyhydroxides (determined as the difference between Fe in dithionate citrate and oxalate extractions) to be the strongest predictor for soil C content, while the mean TT of soil C was best predicted from the amount of smectite, which was also related to more easily measured bulk properties such as cation exchange capacity or pH. Combined with previous research on C turnover times in 2 : 1 vs. 1 : 1 clays, our results hold promise for predicting C inventory and persistence based on intrinsic timescales of specific carbon-mineral interactions.

Reducing energy intake and energy density for a sustainable diet: a study based on self-selected diets in French adults.

PubMed

Masset, Gabriel; Vieux, Florent; Verger, Eric Olivier; Soler, Louis-Georges; Touazi, Djilali; Darmon, Nicole

2014-06-01

Studies on theoretical diets are not sufficient to implement sustainable diets in practice because of unknown cultural acceptability. In contrast, self-selected diets can be considered culturally acceptable. The objective was to identify the most sustainable diets consumed by people in everyday life. The diet-related greenhouse gas emissions (GHGE) for self-selected diets of 1918 adults participating in the cross-sectional French national dietary survey Individual and National Survey on Food Consumption (INCA2) were estimated. "Lower-Carbon," "Higher-Quality," and "More Sustainable" diets were defined as having GHGE lower than the overall median value, a probability of adequate nutrition intake (PANDiet) score (a measure of the overall nutritional adequacy of a diet) higher than the overall median value, and a combination of both criteria, respectively. Diet cost, as a proxy for affordability, and energy density were also assessed. More Sustainable diets were consumed by 23% of men and 20% of women, and their GHGE values were 19% and 17% lower than the population average (mean) value, respectively. In comparison with the average value, Lower-Carbon diets achieved a 20% GHGE reduction and lower cost, but they were not sustainable because they had a lower PANDiet score. Higher-Quality diets were not sustainable because of their above-average GHGE and cost. More Sustainable diets had an above-average PANDiet score and a below-average energy density, cost, GHGE, and energy content; the energy share of plant-based products was increased by 20% and 15% compared with the average for men and women, respectively. A strength of this study was that most of the dimensions for "sustainable diets" were considered, ie, not only nutritional quality and GHGE but also affordability and cultural acceptability. A reduction in diet-related GHGE by 20% while maintaining high nutritional quality seems realistic. This goal could be achieved at no extra cost by reducing energy intake and energy density and increasing the share of plant-based products. © 2014 American Society for Nutrition.

A potential utilization of end-of-life tyres as recycled carbon black in EPDM rubber.

PubMed

Sagar, M; Nibedita, K; Manohar, N; Kumar, K Raj; Suchismita, S; Pradnyesh, A; Reddy, A Babul; Sadiku, E Rotimi; Gupta, U N; Lachit, P; Jayaramudu, J

2018-04-01

End-of-life (EOL) tyres and their decomposition present severe environmental concern due to their resistance to moisture, oxygen, natural degradation, etc. Pyrolysis is considered to be the most effective and sustainable process for recycling, due to its eco-friendly process. The current work studied the effect of recycled carbon black (rCB), obtained from the pyrolysis of EOL tyres, on the properties of ethylene propylene diene rubber (EPDM). The rCB was characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and chemical methods. rCB was incorporated solely, into a conventional EPDM formulation and also in combination with N550 carbon black. The physico-mechanical properties of the EPDM vulcanizates, before and after aging, were succinctly studied by SEM, TGA, Differential Scanning Calorimetry (DSC), tensile tests and cross-link density. The average particle size of rCB was observed to be 8 µm and the ash content was observed to be higher when compared to the conventional N550 carbon black, which was evident, by the TGA and SEM-EDX analyses. The reinforcing effect and the cross-link density of the rCB-filled vulcanizates were found to be marginally inferior in comparison to the conventional carbon black (N550). The morphology of the tensile- and tear-fractured surfaces were studied by SEM and it was observed that the breaking mechanism follows the rubber chain detachment from the surface mode. Copyright © 2018 Elsevier Ltd. All rights reserved.

High capacity carbon dioxide sorbent

DOEpatents

Dietz, Steven Dean; Alptekin, Gokhan; Jayaraman, Ambalavanan

2015-09-01

The present invention provides a sorbent for the removal of carbon dioxide from gas streams, comprising: a CO.sub.2 capacity of at least 9 weight percent when measured at 22.degree. C. and 1 atmosphere; an H.sub.2O capacity of at most 15 weight percent when measured at 25.degree. C. and 1 atmosphere; and an isosteric heat of adsorption of from 5 to 8.5 kilocalories per mole of CO.sub.2. The invention also provides a carbon sorbent in a powder, a granular or a pellet form for the removal of carbon dioxide from gas streams, comprising: a carbon content of at least 90 weight percent; a nitrogen content of at least 1 weight percent; an oxygen content of at most 3 weight percent; a BET surface area from 50 to 2600 m.sup.2/g; and a DFT micropore volume from 0.04 to 0.8 cc/g.

The application of pulse modulated plasma to the plasma enhanced chemical vapor deposition of dielectric materials

NASA Astrophysics Data System (ADS)

Qi, Yu

This dissertation work applied the pulse modulated plasma to the plasma enhanced chemical vapor deposition (PECVD) of two types of dielectric materials: SiO2-like coatings and Teflon-like coatings. SiO2-like coatings were firstly implemented with continuous plasma. It was proven that three different precursors: hexamethyldisiloxane (HMDSO), 1, 3, 5, 7-tetramethylcyclotetrasiloxane (TMCTS) and octamethylcyclotetrasiloxane (OMCTS) can be used to generate hard, clear and high density SiO2 deposition with coupled high growth rate and low processing temperature via PECVD. Under similar conditions, HMDSO has the lowest growth rate, lowest hardness and highest carbon content; TMCTS has the highest growth rate and hardness, and lowest carbon content; and OMCTS has moderate rates of these deposition qualities, but the best corrosion resistance. Substrate bias seems to have no effect on any deposition quality. High chamber pressure can significantly lower the carbon content in the thin films but does not affect any other qualities; the O2/precursor ratio is the most influential factor among all variables considered in this experiment. The deposition hardness and O:Si ratio always increase with this ratio while the carbon content always decreases. However, different precursors require different optimal ratios to achieve the highest growth rate. Pulse modulation was introduced into PECVD of SiO2-like coatings and OMCTS was selected as the precursor. It was demonstrated that pulse frequency, duty ratio and peak power have significant effects on deposition qualities. The proper combination of the pulse parameters and other traditional plasma parameters can significantly lower the processing temperature while retaining or even improving other deposition qualities, such as growth rate, corrosion resistance and elemental composition. Hardness is the only sacrifice of the lower time-average power caused by pulsing. Therefore, pulse modulation can effectively expand the possible range of combinations of desired deposition qualities. Finally, the pulsed plasma was used to implement PECVD of teflon-like coatings. An important discovery in this application is that in addition to pulse period, on-time and on-time peak power, the power level during the off-time is an important factor. The density of CF2 is a function of all these pulse parameters. The best result obtained is up to 67.2% CF2 and a 1.87:1 of F:C ratio when the off-time power level is ˜100--130 W the frequency is several Hz, the on-time peak power is ˜1000 W and the duty ratio is ˜7--10%.

Spatial variation of salt-marsh organic and inorganic deposition and organic carbon accumulation: Inferences from the Venice lagoon, Italy

NASA Astrophysics Data System (ADS)

Roner, M.; D'Alpaos, A.; Ghinassi, M.; Marani, M.; Silvestri, S.; Franceschinis, E.; Realdon, N.

2016-07-01

Salt marshes are ubiquitous features of the tidal landscape governed by mutual feedbacks among processes of physical and biological nature. Improving our understanding of these feedbacks and of their effects on tidal geomorphological and ecological dynamics is a critical step to address issues related to salt-marsh conservation and response to changes in the environmental forcing. In particular, the spatial variation of organic and inorganic soil production processes at the marsh scale, a key piece of information to understand marsh responses to a changing climate, remains virtually unexplored. In order to characterize the relative importance of organic vs. inorganic deposition as a function of space, we collected 33 shallow soil sediment samples along three transects in the San Felice and Rigà salt marshes located in the Venice lagoon, Italy. The amount of organic matter in each sample was evaluated using Loss On Ignition (LOI), a hydrogen peroxide (H2O2) treatment, and a sodium hypochlorite (NaClO) treatment following the H2O2 treatment. The grain size distribution of the inorganic fraction was determined using laser diffraction techniques. Our study marshes exhibit a weakly concave-up profile, with maximum elevations and coarser inorganic grains along their edges. The amount of organic and inorganic matter content in the samples varies with the distance from the marsh edge and is very sensitive to the specific analysis method adopted. The use of a H2O2+NaClO treatment yields an organic matter density value which is more than double the value obtained from LOI. Overall, inorganic contributions to soil formation are greatest near the marsh edges, whereas organic soil production is the main contributor to soil accretion in the inner marsh. We interpret this pattern by considering that while plant biomass productivity is generally lower in the inner part of the marsh, organic soil decomposition rates are highest in the better aerated edge soils. Hence the higher inorganic soil content near the edge is due to the preferential deposition of inorganic sediment from the adjacent creek, and to the rapid decomposition of the relatively large biomass production. The higher organic matter content in the inner part of the marsh results from the small amounts of suspended sediment that makes it to the inner marsh, and to the low decomposition rate which more than compensates for the lower biomass productivity in the low-lying inner zones. Finally, the average soil organic carbon density from the LOI measurements is estimated to be 0.044 g C cm-3. The corresponding average carbon accumulation rate for the San Felice and Rigà salt marshes, 132 g C m-2 yr-1, highlights the considerable carbon stock and sequestration rate associated with coastal salt marshes.

Export of dissolved carbonaceous and nitrogenous substances in rivers of the "Water Tower of Asia".

PubMed

Qu, Bin; Sillanpää, Mika; Kang, Shichang; Yan, Fangping; Li, Zhiguo; Zhang, Hongbo; Li, Chaoliu

2018-03-01

Rivers are critical links in the carbon and nitrogen cycle in aquatic, terrestrial, and atmospheric environments. Here riverine carbon and nitrogen exports in nine large rivers on the Tibetan Plateau - the "Water Tower of Asia" - were investigated in the monsoon season from 2013 to 2015. Compared with the world average, concentrations of dissolved inorganic carbon (DIC, 30.7mg/L) were high in river basins of the plateau due to extensive topographic relief and intensive water erosion. Low concentrations of dissolved organic carbon (DOC, 1.16mg/L) were likely due to the low temperature and unproductive land vegetation environments. Average concentrations of riverine DIN (0.32mg/L) and DON (0.35 mg/L) on the Tibetan Plateau were close to the world average. However, despite its predominantly pristine environment, discharge from agricultural activities and urban areas of the plateau has raised riverine N export. In addition, DOC/DON ratio (C/N, ~6.5) in rivers of the Tibetan Plateau was much lower than the global average, indicating that dissolved organic carbon in the rivers of this region might be more bioavailable. Therefore, along with global warming and anthropogenic activities, increasing export of bioavailable riverine carbon and nitrogen from rivers of the Tibetan Plateau can be expected in the future, which will possibly influence the regional carbon and nitrogen cycle. Copyright © 2017. Published by Elsevier B.V.

Carbon Coated Boron Nitride Nanosheets for Polymer Nanocomposites with Enhanced Dielectric Performance

PubMed Central

Yang, Minhao; Zhao, Hang; He, Delong; Hu, Chaohe; Chen, Haowei; Bai, Jinbo

2017-01-01

Carbon coated boron nitride nanosheets (BNNSs@C) hybrids with different carbon contents were synthesized by a chemical vapor deposition (CVD) method. The content of carbon in as-obtained BNNSs@C hybrids could be precisely adjusted from 2.50% to 22.62% by controlling the carbon deposition time during the CVD procedure. Afterward, the BNNSs@C hybrids were subsequently incorporated into the polyvinylidene fluoride (PVDF) matrix to fabricate the BNNSs@C/PVDF nanocomposites through a combination of solution and melting blending methods. The dielectric properties of the as-obtained BNNSs@C/PVDF nanocomposites could be accurately tuned by adjusting the carbon content. The resultant nanocomposites could afford a high dielectric constant about 39 (103 Hz) at BNNSs@C hybrids loading of 30 vol %, which is 4.8 times larger than that of pristine BNNSs-filled ones at the same filler loading, and 3.5 times higher than that of pure PVDF matrix. The largely enhanced dielectric performance could be ascribed to the improved interfacial polarizations of BNNSs/carbon and carbon/PVDF interfaces. The approach reported here offers an effective and alternative method to fabricate high-performance dielectric nanocomposites, which could be potentially applied to the embedded capacitors with high dielectric performance. PMID:28773105

Testing of some assumptions about biodegradability in soil as measured by carbon dioxide evolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

El-Din Sharabi, N.; Bartha, R.

1993-04-01

The Toxic Substance Control Act calls for a premanufacturing review of novel chemical substances including their biodegradability. Carbon dioxide evolution, using non-labeled carbon or [sup 14]C, is a common method of testing. This study examines assumptions of carbon dioxide evolution testing. Test substances used included: glucose, adipic acid, benzoic acid, and n-hexadecane. Chemical composition other than carbon content appears to influence minimally the percentages conversion to CO[sub 2]. However, that although CO[sub 2] evolution seemed proportional to the carbon content and concentration of the test substance, at least one-half of the evolved net CO[sub 2] did not come directly frommore » the test substance. Conversion to CO[sub 2] in the soil appeared to depend on carbon content only. In experiments of 1 month or longer, the net CO[sub 2] evolution in response to substrate may be above 100% of the added substrate carbon. Whether this applies to all substrate additions remains to be studied. The authors conclude that net CO[sub 2] and [sup 14]CO[sub 2] evolution measurements are useful as a first-tier tests for assessing biodegradability in soil. 11 refs., 6 figs.« less

Phytomass & Carbon estimation of Tree outside Forests, their role and effect in maintaing microclimate of local environment: A Remote Sensing Approach in Gwalior and Sheopur District, Madhya Pradesh

NASA Astrophysics Data System (ADS)

Uniyal, S.; Singh, S.; Rao, S. S.

2017-12-01

Trees Outside Forest (TOF) grow on a variety of landscapes , e.g. linear, scattered, block etc. and include unique range of species that are specific to the local environmental and socio-cultural conditions. TOF usefulness came into knowledge when the ongoing anthropogenic activities increases the CO2 concentration in the atmosphere and it has been understood that CO2 can also be sequestered by increasing rate of afforestation.This study illustrates a methodology to estimate individual tree phytomass, their contribution to the environment and microclimate, spatial distribution of TOF phytomass and their carbon storage in Gwalior and Sheopur districts of Madhya Pradesh using very high resolution satellite data. Attempt has been made to estimate phytomass at pixel level also using various regression models. Phytomass is an important parameter to assess the atmospheric carbon that is harvested by trees .More the amount of phytomass more will be the Carbon content of trees and in similar way more will be their contribution for regulation of CO2 and vice versa. Tree Canopies extraction was done using very high resolution satellite data within an area of 5´5 km grids using various remote sensing techniques. Field data were collected from different types of TOFs, e.g. linear, scattered, block etc. from varying plot shapes and sizes, and Stratum-wise phytomass was estimated. Findings of study reported here says that varying phytomass range has been observed for road, agriculture and settlement with varying number of individual trees.The Phytomass in scattered TOFs varied from 0.22 to 15.68 t/ha and carbon content 0.104 to 7.4tC whereas, in linear TOFs it varied from 5.26 to 156.71 t/ha with carbon content 2.49 to 74.43tC. Phytomass along the road-side varied from 20.75 to 879.8 t/ha and carbon content 9.85 to 417.90 tC. Stratum-wise total phytomass and carbon content in areas having TOF was estimated. Of the 10 grids considered, the maximum Phytomass of 1363 tonnes with carbon content 647.425tC was recorded around Gwalior airport and minimum of 367.55 tonnes and carbon content 174.325tC in the surroundings of Mohana town. Analysis has been performed on how climatic variables affect the growth and structure of these trees and vice versa.

Carbon fiber content measurement in composite

NASA Astrophysics Data System (ADS)

Wang, Qiushi

Carbon fiber reinforced polymers (CFRPs) have been widely used in various structural applications in industries such as aerospace and automotive because of their high specific stiffness and specific strength. Their mechanical properties are strongly influenced by the carbon fiber content in the composites. Measurement of the carbon fiber content in CFRPs is essential for product quality control and process optimization. In this work, a novel carbonization-in-nitrogen method (CIN) is developed to characterize the fiber content in carbon fiber reinforced thermoset and thermoplastic composites. In this method, a carbon fiber composite sample is carbonized in a nitrogen environment at elevated temperatures, alongside a neat resin sample. The carbon fibers are protected from oxidization while the resin (the neat resin and the resin matrix in the composite sample) is carbonized under the nitrogen environment. The residue of the carbonized neat resin sample is used to calibrate the resin carbonization rate and calculate the amount of the resin matrix in the composite sample. The new method has been validated on several thermoset and thermoplastic resin systems and found to yield an accurate measurement of fiber content in carbon fiber polymer composites. In order to further understand the thermal degradation behavior of the high temperature thermoplastic polymer during the carbonization process, the mechanism and the kinetic model of thermal degradation behavior of carbon fiber reinforced poly (phenylene sulfide) (CPPS) are studied using thermogravimetry analysis (TGA). The CPPS is subjected to TGA in an air and nitrogen atmosphere at heating rates from 5 to 40°C min--1. The TGA curves obtained in air are different from those in nitrogen. This demonstrates that weight loss occurs in a single stage in nitrogen but in two stages in air. To elucidate this difference, thermal decomposition kinetics is analyzed by applying the Kissinger, Flynn-Wall-Ozawa, Coat-Redfern and Malek methods. The activation energy (Ea) of the solid-state process is determined to be 202 kJ mol--1 in an oxidative atmosphere using Kissinger's method, which is 10-15 kJ mol--1 more than the results calculated in a nitrogen atmosphere. The value of the activation energy obtained using Ozawa-Flynn methods is in agreement with that using the Kissinger method. Different degradation mechanisms are used to compare with this value. Based on the analytical result, the actual thermal degradation mechanism of the CPPS is a Dn deceleration type. The carbonization temperature range of the CPPS is the same as pure PPS resin.

Assessment of soil organic carbon stocks under future climate and land cover changes in Europe.

PubMed

Yigini, Yusuf; Panagos, Panos

2016-07-01

Soil organic carbon plays an important role in the carbon cycling of terrestrial ecosystems, variations in soil organic carbon stocks are very important for the ecosystem. In this study, a geostatistical model was used for predicting current and future soil organic carbon (SOC) stocks in Europe. The first phase of the study predicts current soil organic carbon content by using stepwise multiple linear regression and ordinary kriging and the second phase of the study projects the soil organic carbon to the near future (2050) by using a set of environmental predictors. We demonstrate here an approach to predict present and future soil organic carbon stocks by using climate, land cover, terrain and soil data and their projections. The covariates were selected for their role in the carbon cycle and their availability for the future model. The regression-kriging as a base model is predicting current SOC stocks in Europe by using a set of covariates and dense SOC measurements coming from LUCAS Soil Database. The base model delivers coefficients for each of the covariates to the future model. The overall model produced soil organic carbon maps which reflect the present and the future predictions (2050) based on climate and land cover projections. The data of the present climate conditions (long-term average (1950-2000)) and the future projections for 2050 were obtained from WorldClim data portal. The future climate projections are the recent climate projections mentioned in the Fifth Assessment IPCC report. These projections were extracted from the global climate models (GCMs) for four representative concentration pathways (RCPs). The results suggest an overall increase in SOC stocks by 2050 in Europe (EU26) under all climate and land cover scenarios, but the extent of the increase varies between the climate model and emissions scenarios. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

The distribution of organic carbon fractions in a typical loess-paleosol profile and its paleoenvironmental significance

PubMed Central

Hu, Feinan; Huo, Na; Shang, Yingni; Chang, Wenqian

2018-01-01

Background The loess-paleosol sequence on the Loess Plateau has been considered an important paleoclimatic archive to study global climatic and environmental changes in the Quaternary. So far, little attention has been paid to the characteristics of soil organic carbon fractions in loess-paleosol sequences, which may provide valuable information for exploring the evolution of climate and environment in the Quaternary on the Loess Plateau. Methods In order to explore the significance of mineral-associated organic carbon to total organic carbon (MOC/TOC) ratios in the loess-paleosol sequence for reconstructing paleoenvironmental and paleoclimatic evolution in the Quaternary on the Loess Plateau, we selected a typical loess-paleosol profile in Chunhua county, Xianyang city, Shaanxi province, as the research object. The content of total organic carbon (TOC) and MOC/TOC ratio in each loess and paleosol layers of the Chunhua loess-paleosol profile were analyzed, together with the paleoclimatic proxies, such as soil grain size, CaCO3 content and their correlations with organic carbon parameters. Results The main results were as follows: (1) the total content of soil organic carbon and MOC/TOC ratios were generally higher in paleosol layers than in the underlying loess layers of the Chunhua loess-paleosol profile. Compared to total organic carbon content, MOC/TOC ratios changed more obviously in soil layers below a paleosol layer S8; (2) soil clay content and median grain size (Md (ϕ)) were higher in paleosol than in the underlying loess, while CaCO3 content showed an opposite tendency. In the Chunhua profile, the distribution characteristics of the three paleoclimatic proxies showed good indications of paleoclimate changes in the Quaternary; (3) in the Chunhua loess-paleosol profile, MOC/TOC ratios were positively correlated with clay content and median grain size (ϕ), while negatively correlated with CaCO3 content, and the correlations were more significant in soil layers below S8. Discussion Our results indicated that MOC/TOC ratios in the Chunhua loess-paleosol profile correlated with the cold dry-warm wet paleoclimatic cycle in the Quaternary. The high MOC/TOC ratios in the loess-paleosol profile might reflect warm and humid climate, while lower ratios indicated relatively cold and dry climate. That is because when the climate changed from warm-humid to cold-dry, the vegetation coverage and pedogenesis intensity decreased, which increased soil CaCO3 content and decreased soil clay content and Md (ϕ), leading to decreased MOC/TOC ratios. Compared to TOC, MOC/TOC ratios had greater significance in indicating paleoenvironmental evolution in the Quaternary on the Loess Plateau. Therefore, investigating MOC/TOC ratios in loess-paleosol profile can offer new evidence to reconstructing paleoenvironmental changes, and also provide a basis for predicting responses of soil organic carbon pools to vegetation and climate changes in the future. PMID:29666763

Upper Paleozoic Marine Shale Characteristics and Exploration Prospects in the Northwestern Guizhong Depression, South China

NASA Astrophysics Data System (ADS)

Zhu, Zhenhong; Yao, Genshun; Lou, Zhanghua; Jin, Aimin; Zhu, Rong; Jin, Chong; Chen, Chao

2018-05-01

Multiple sets of organic-rich shales developed in the Upper Paleozoic of the northwestern Guizhong Depression in South China. However, the exploration of these shales is presently at a relatively immature stage. The Upper Paleozoic shales in the northwestern Guizhong Depression, including the Middle Devonian Luofu shale, the Nabiao shale, and the Lower Carboniferous Yanguan shale, were investigated in this study. Mineral composition analysis, organic matter analysis (including total organic carbon (TOC) content, maceral of kerogen and the vitrinite reflection (Ro)), pore characteristic analysis (including porosity and permeability, pore type identification by SEM, and pore size distribution by nitrogen sorption), methane isothermal sorption test were conducted, and the distribution and thickness of the shales were determined, Then the characteristics of the two target shales were illustrated and compared. The results show that the Upper Paleozoic shales have favorable organic matter conditions (mainly moderate to high TOC content, type I and II1 kerogen and high to over maturity), good fracability potential (brittleness index (BI) > 40%), multiple pore types, stable distribution and effective thickness, and good methane sorption capacity. Therefore, the Upper Paleozoic shales in the northern Guizhong Depression have good shale gas potential and exploration prospects. Moreover, the average TOC content, average BI, thickness of the organic-rich shale (TOC > 2.0 wt%) and the shale gas resources of the Middle Devonian shales are better than those of the Lower Carboniferous shale. The Middle Devonian shales have better shale gas potential and exploration prospects than the Lower Carboniferous shales.

Physical and biochemical properties of the euphausiids Thysanoessa inermis, Thysanoessa raschii, and Thysanoessa longipes in the eastern Bering Sea

NASA Astrophysics Data System (ADS)

Harvey, H. Rodger; Pleuthner, Rachel L.; Lessard, Evelyn J.; Bernhardt, Megan J.; Tracy Shaw, C.

2012-06-01

Euphausiids are an integral part of the Bering Sea ecosystem, linking primary production to upper level trophic levels as both consumers and prey. Species native to this region extend over a range of geographic provinces and serve as a critical component of the movement of energy through the food web. As one facet of the BEST-BSIERP Bering Sea program, we determined the proximate composition and essential allometric relationships of multiple species of euphausiids collected over three years in the eastern Bering Sea. Three euphausiid species were examined: Thysanoessa inermis, Thysanoessa raschii, and Thysanoessa longipes. While the three species were similar with respect to size, T. inermis had the highest average wet and dry weights per size class, as well as highest carbon and caloric concentrations. Among the three species, T. inermis and T. longipes had similar lipid concentrations, with T. longipes showing higher average lipid concentrations. Empirical equations were developed to describe fundamental relationships between length, weight, PC/PN, and calorie and lipid content for the three species over the full range of sizes encountered in the study area. Such relationships increase our understanding of how euphausiids contribute to the carbon budget and energy input in the eastern Bering Sea system and help to define realistic parameters for ongoing and future modeling efforts.

[Phosphorus removal characteristics by aerobic granules in normal molasses wastewater after anaerobic treatment].

PubMed

Wang, Shuo; Yu, Shui-Li; Shi, Wen-Xin; Bao, Rui-Ling; Yi, Xue-Song; Li, Jian-Zheng

2012-04-01

COD decreased obviously in normal molasses wastewater after anaerobic treatment, however, concentrations of nitrogen and phosphorus were still higher in the effluent which seriously damaged the ecological balance. In this study, aerobic granules cultivated in sequencing batch airlift reactor (SBAR) were carried out for treating the effluent; phosphorus removal processes and characteristics were discussed as well. The mean diameter of aerobic granules cultivated by multiple carbon sources (acetate, propionate and butyrate) was 1.7 mm. The average phosphorus removal efficiency was 90.9% and the level of phosphorus in effluent was only 1.3 mg x L(-1); TP released per COD consumed was 0.571 and the specific rate of TP released was 5.73 mg x (g x h)(-1). NO3(-) -N usage of phosphorus accumulating organisms (PAOs) improved during denitrifying process because the concentration of propionate and butyrate increased in multiple carbon sources which means the phosphorus uptake efficiency increased when per NO3(-) -N consumed. Phosphorus content represented a stronger correlation with magnesium, calcium and ferrum contents in aerobic granules and their extracellular polymeric substances (EPS), the phosphorus adsorption by EPS could enhance phosphorus removal. 61.9% of phosphorus accumulating organisms were denitrifying phosphorus accumulating organisms in aerobic granules and TP uptake per NO3(-) -N consumed was 1.14 which was higher than that of aerobic granules only cultivated by acetate.

Hydrates of nat­ural gas in continental margins

USGS Publications Warehouse

Kvenvolden, K.A.; Barnard, L.A.

1982-01-01

Natural gas hydrates in continental margin sediment can be inferred from the widespread occurrence of an anomalous seismic reflector which coincides with the predicted transition boundary at the base of the gas hydrate zone. Direct evidence of gas hydrates is provided by visual observations of sediments from the landward wall of the Mid-America Trench off Mexico and Guatemala, from the Blake Outer Ridge off the southeastern United States, and from the Black Sea in the U.S.S.R. Where solid gas hydrates have been sampled, the gas is composed mainly of methane accompanied by CO2 and low concentrations of ethane and hydrocarbons of higher molecular weight. The molecular and isotopic composition of hydrocarbons indicates that most of the methane is of biolog cal origin. The gas was probably produced by the bacterial alteration of organic matter buried in the sediment. Organic carbon contents of the sediment containing sampled gas hydrates are higher than the average organic carbon content of marine sediments. The main economic importance of gas hydrates may reside in their ability to serve as a cap under which free gas can collect. To be producible, however, such trapped gas must occur in porous and permeable reservoirs. Although gas hydrates are common along continental margins, the degree to which they are associated with significant reservoirs remains to be investigated.

Estimation of Carbon Sink in Surface Carbonate Rocks of Guangxi Province by Using Remote Sensing Images

NASA Astrophysics Data System (ADS)

Jia, B.; Zhou, G.; Wang, H.; Yue, T.; Huang, W.

2018-04-01

Studies of the imbalance of source sinks in the carbon cycle show that CO2 absorbed during rock weathering is part of the "miss carbon" of the global carbon cycle. The carbon sink contribution of carbonate rocks obviously plays a very important role in the absorption of atmospheric CO2. Estimation of carbon sinks in karst dynamic system of Guangxi province has great significance for further understanding of global karst carbon cycle and global climate research. This paper quotes the rock data from Tao Xiaodong's paper, which is obtained using RS and GIS techniques. At the same time, the dissolution rate model studied by Zhou Guoqing and others was used to estimate the dissolution rate of carbonate rocks in Guangxi Province. Finally, the CO2 content consumed by carbonate karstification in Guangxi Province was 1342910.447 t a-1. The results obtained are in the same order of magnitude as the CO2 content consumed by carbonate rock karstification in Guangxi Province calculated by Tao Xiaodong.

cyclostratigraphy, sequence stratigraphy and organic matter accumulation mechanism

NASA Astrophysics Data System (ADS)

Cong, F.; Li, J.

2016-12-01

The first member of Maokou Formation of Sichuan basin is composed of well preserved carbonate ramp couplets of limestone and marlstone/shale. It acts as one of the potential shale gas source rock, and is suitable for time-series analysis. We conducted time-series analysis to identify high-frequency sequences, reconstruct high-resolution sedimentation rate, estimate detailed primary productivity for the first time in the study intervals and discuss organic matter accumulation mechanism of source rock under sequence stratigraphic framework.Using the theory of cyclostratigraphy and sequence stratigraphy, the high-frequency sequences of one outcrop profile and one drilling well are identified. Two third-order sequences and eight fourth-order sequences are distinguished on outcrop profile based on the cycle stacking patterns. For drilling well, sequence boundary and four system tracts is distinguished by "integrated prediction error filter analysis" (INPEFA) of Gamma-ray logging data, and eight fourth-order sequences is identified by 405ka long eccentricity curve in depth domain which is quantified and filtered by integrated analysis of MTM spectral analysis, evolutive harmonic analysis (EHA), evolutive average spectral misfit (eASM) and band-pass filtering. It suggests that high-frequency sequences correlate well with Milankovitch orbital signals recorded in sediments, and it is applicable to use cyclostratigraphy theory in dividing high-frequency(4-6 orders) sequence stratigraphy.High-resolution sedimentation rate is reconstructed through the study interval by tracking the highly statistically significant short eccentricity component (123ka) revealed by EHA. Based on sedimentation rate, measured TOC and density data, the burial flux, delivery flux and primary productivity of organic carbon was estimated. By integrating redox proxies, we can discuss the controls on organic matter accumulation by primary production and preservation under the high-resolution sequence stratigraphic framework. Results show that high average organic carbon contents in the study interval are mainly attributed to high primary production. The results also show a good correlation between high organic carbon accumulation and intervals of transgression.

Selenium speciation and extractability in Dutch agricultural soils.

PubMed

Supriatin, Supriatin; Weng, Liping; Comans, Rob N J

2015-11-01

The study aimed to understand selenium (Se) speciation and extractability in Dutch agricultural soils. Top soil samples were taken from 42 grassland fields and 41 arable land fields in the Netherlands. Total Se contents measured in aqua regia were between 0.12 and 1.97 mg kg(-1) (on average 0.58 mg kg(-1)). Organic Se after NaOCl oxidation-extraction accounted for on average 82% of total Se, whereas inorganic selenite (selenate was not measurable) measured in ammonium oxalate extraction using HPLC-ICP-MS accounted for on average 5% of total Se. The predominance of organic Se in the soils is supported by the positive correlations between total Se (aqua regia) and total soil organic matter content, and Se and organic C content in all the other extractions performed in this study. The amount of Se extracted followed the order of aqua regia > 1 M NaOCl (pH8) > 0.1 M NaOH>ammonium oxalate (pH3) > hot water>0.43 M HNO3 > 0.01 M CaCl2. None of these extractions selectively extracts only inorganic Se, and relative to other extractions 0.43 M HNO3 extraction contains the lowest fraction of organic Se, followed by ammonium oxalate extraction. In the 0.1M NaOH extraction, the hydrophobic neutral (HON) fraction of soil organic matter is richer in Se than in the hydrophilic (Hy) and humic acid (HA) fractions. The organic matter extracted in 0.01 M CaCl2 and hot water is in general richer in Se compared to the organic matter extracted in 0.1M NaOH, and other extractions (HNO3, ammonium oxalate, NaOCl, and aqua regia). Although the extractability of Se follows to a large extent the extractability of soil organic carbon, there is several time variations in the Se to organic C ratios, reflecting the changes in composition of organic matter extracted. Copyright © 2015 Elsevier B.V. All rights reserved.

Organic carbon content of marine aerosols collected on Bermuda

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoffman, E.J.; Duce, R.A.

1974-01-01

The concentration of total organic carbon in marine aerosols collected from a 20-m tower on the Southwest Coast of Bermuda ranged from 0.15 to 0.47 microgram/M/sup 3/ STP under onshore wind conditions. The mass of the organic carbon ranged from 1 to 19% of the mass of sea salt in the particles in Bermuda, and the percentage decreased with increasing salt content.

Novel technique to suppress hydrocarbon contamination for high accuracy determination of carbon content in steel by FE-EPMA

PubMed Central

Yamashita, Takako; Tanaka, Yuji; Yagoshi, Masayasu; Ishida, Kiyohito

2016-01-01

In multiphase steels, control of the carbon contents in the respective phases is the most important factor in alloy design for achieving high strength and high ductility. However, it is unusually difficult to determine the carbon contents in multiphase structures with high accuracy by electron probe microanalysis (EPMA) due to the unavoidable effect of hydrocarbon contamination during measurements. We have investigated new methods for suppressing hydrocarbon contamination during field emission (FE) EPMA measurements as well as a conventional liquid nitrogen trap. Plasma cleaner inside the specimen chamber results in a improvement of carbon-content determination by point analysis, increasing precision tenfold from the previous 0.1 mass%C to 0.01 mass%C. Stage heating at about 100 °C dramatically suppresses contamination growth during continuous point measurement and mapping. By the combination of above two techniques, we successfully visualized the two-dimensional carbon distribution in a dual-phase steel. It was also noted that the carbon concentrations at the ferrite/martensite interfaces were not the same across all interfaces, and local variation was observed. The developed technique is expected to be a powerful tool for understanding the mechanisms of mechanical properties and microstructural evolution, thereby contributing to the design of new steel products with superior properties. PMID:27431281

Carbon Sequestration in Created and Natural Tidal Marshes of the Florida Panhandle

NASA Astrophysics Data System (ADS)

Rainville, K. M.; Davis, J.; Currin, C.

2016-12-01

Salt marshes are widely understood to be efficient at storing carbon in sediments (aka blue carbon) through the production of roots and rhizomes. These marshes are also able to trap sediments from incoming tides, slowly increasing their elevation over time. These qualities have led to a great deal of interest in creation and preservation of salt marshes for offsetting changes associated with anthropogenic CO2 emissions. Determinations of the value of marshes in terms of CO2 offsets requires detailed knowledge of sediment carbon storage rates, but to date, measured rates of carbon storage in created salt marsh sediments are sparse. We measured carbon storage in natural and created marshes along the Northern Gulf Coast of Florida. The created marshes were in `living shoreline' projects and ranged in age from 8 to 28 years. Dominant plant cover of the marshes included Spartina alterniflora and Juncus spp. At all sites, sediment cores (22-75 cm in depth) were collected, extruded in 5 cm increments, and carbon content was determined by elemental analysis. Measured C storage rates in the created marshes ranged from 60 to 130 g C m-2 yr-1 and decreased with marsh age. A decrease in storage rates over time is evidence of continued decomposition of stored carbon as sediments age, an important factor to consider when estimating the value of a given marsh for CO2 offsets. The rates measured in Florida are well below previously published average values ( 200 g m-2 yr-1) and also below the default value allowed for carbon crediting through the verified carbon standard (146 g m-2 yr), but similar to those measured in created marshes in North Carolina. In addition, factors such as dominant plant type, water inundation, temperature, latitude, biological belowground activity and biomass values can impact carbon storage rates of marshes among geographically distinct regions. This makes it especially important to determine carbon storage rates on a local scale, and not following a verified carbon standard. These data add to the geographic coverage over which documented C storage rates are currently available and suggest that locally determined rates are necessary for accurate carbon accounting.

Projection of corn production and stover-harvesting impacts on soil organic carbon dynamics in the U.S. Temperate Prairies.

PubMed

Wu, Yiping; Liu, Shuguang; Young, Claudia J; Dahal, Devendra; Sohl, Terry L; Davis, Brian

2015-06-01

Terrestrial carbon sequestration potential is widely considered as a realistic option for mitigating greenhouse gas emissions. However, this potential may be threatened by global changes including climate, land use, and management changes such as increased corn stover harvesting for rising production of cellulosic biofuel. Therefore, it is critical to investigate the dynamics of soil organic carbon (SOC) at regional or global scale. This study simulated the corn production and spatiotemporal changes of SOC in the U.S. Temperate Prairies, which covers over one-third of the U.S. corn acreage, using a biogeochemical model with multiple climate and land-use change projections. The corn production (either grain yield or stover biomass) could reach 88.7-104.7 TgC as of 2050, 70-101% increase when compared to the base year of 2010. A removal of 50% stover at the regional scale could be a reasonable cap in view of maintaining SOC content and soil fertility especially in the beginning years. The projected SOC dynamics indicated that the average carbon sequestration potential across the entire region may vary from 12.7 to 19.6 g C/m(2)/yr (i.e., 6.6-10.2 g TgC/yr). This study not only helps understand SOC dynamics but also provides decision support for sustainable biofuel development.

Projection of corn production and stover-harvesting impacts on soil organic carbon dynamics in the U.S. Temperate Prairies

USGS Publications Warehouse

Wu, Yiping; Liu, Shuguang; Young, Claudia J.; Dahal, Devendra; Sohl, Terry L.; Davis, Brian

2015-01-01

Terrestrial carbon sequestration potential is widely considered as a realistic option for mitigating greenhouse gas emissions. However, this potential may be threatened by global changes including climate, land use, and management changes such as increased corn stover harvesting for rising production of cellulosic biofuel. Therefore, it is critical to investigate the dynamics of soil organic carbon (SOC) at regional or global scale. This study simulated the corn production and spatiotemporal changes of SOC in the U.S. Temperate Prairies, which covers over one-third of the U.S. corn acreage, using a biogeochemical model with multiple climate and land-use change projections. The corn production (either grain yield or stover biomass) could reach 88.7–104.7 TgC as of 2050, 70–101% increase when compared to the base year of 2010. A removal of 50% stover at the regional scale could be a reasonable cap in view of maintaining SOC content and soil fertility especially in the beginning years. The projected SOC dynamics indicated that the average carbon sequestration potential across the entire region may vary from 12.7 to 19.6 g C/m2/yr (i.e., 6.6–10.2 g TgC/yr). This study not only helps understand SOC dynamics but also provides decision support for sustainable biofuel development.

Projection of corn production and stover-harvesting impacts on soil organic carbon dynamics in the U.S. Temperate Prairies

PubMed Central

Wu, Yiping; Liu, Shuguang; Young, Claudia J.; Dahal, Devendra; Sohl, Terry L.; Davis, Brian

2015-01-01

Terrestrial carbon sequestration potential is widely considered as a realistic option for mitigating greenhouse gas emissions. However, this potential may be threatened by global changes including climate, land use, and management changes such as increased corn stover harvesting for rising production of cellulosic biofuel. Therefore, it is critical to investigate the dynamics of soil organic carbon (SOC) at regional or global scale. This study simulated the corn production and spatiotemporal changes of SOC in the U.S. Temperate Prairies, which covers over one-third of the U.S. corn acreage, using a biogeochemical model with multiple climate and land-use change projections. The corn production (either grain yield or stover biomass) could reach 88.7–104.7 TgC as of 2050, 70–101% increase when compared to the base year of 2010. A removal of 50% stover at the regional scale could be a reasonable cap in view of maintaining SOC content and soil fertility especially in the beginning years. The projected SOC dynamics indicated that the average carbon sequestration potential across the entire region may vary from 12.7 to 19.6 g C/m2/yr (i.e., 6.6–10.2 g TgC/yr). This study not only helps understand SOC dynamics but also provides decision support for sustainable biofuel development. PMID:26027873

Increased forest ecosystem carbon and nitrogen storage from nitrogen rich bedrock.

PubMed

Morford, Scott L; Houlton, Benjamin Z; Dahlgren, Randy A

2011-08-31

Nitrogen (N) limits the productivity of many ecosystems worldwide, thereby restricting the ability of terrestrial ecosystems to offset the effects of rising atmospheric CO(2) emissions naturally. Understanding input pathways of bioavailable N is therefore paramount for predicting carbon (C) storage on land, particularly in temperate and boreal forests. Paradigms of nutrient cycling and limitation posit that new N enters terrestrial ecosystems solely from the atmosphere. Here we show that bedrock comprises a hitherto overlooked source of ecologically available N to forests. We report that the N content of soils and forest foliage on N-rich metasedimentary rocks (350-950 mg N kg(-1)) is elevated by more than 50% compared with similar temperate forest sites underlain by N-poor igneous parent material (30-70 mg N kg(-1)). Natural abundance N isotopes attribute this difference to rock-derived N: (15)N/(14)N values for rock, soils and plants are indistinguishable in sites underlain by N-rich lithology, in marked contrast to sites on N-poor substrates. Furthermore, forests associated with N-rich parent material contain on average 42% more carbon in above-ground tree biomass and 60% more carbon in the upper 30 cm of the soil than similar sites underlain by N-poor rocks. Our results raise the possibility that bedrock N input may represent an important and overlooked component of ecosystem N and C cycling elsewhere.

Decomposition characteristics of three different kinds of aquatic macrophytes and their potential application as carbon resource in constructed wetland.

PubMed

Wu, Suqing; He, Shengbing; Zhou, Weili; Gu, Jianya; Huang, Jungchen; Gao, Lei; Zhang, Xu

2017-12-01

Decomposition of aquatic macrophytes usually generates significant influence on aquatic environment. Study on the aquatic macrophytes decomposition may help reusing the aquatic macrophytes litters, as well as controlling the water pollution caused by the decomposition process. This study verified that the decomposition processes of three different kinds of aquatic macrophytes (water hyacinth, hydrilla and cattail) could exert significant influences on water quality of the receiving water, including the change extent of pH, dissolved oxygen (DO), the contents of carbon, nitrogen and phosphorus, etc. The influence of decomposition on water quality and the concentrations of the released chemical materials both followed the order of water hyacinth > hydrilla > cattail. Greater influence was obtained with higher dosage of plant litter addition. The influence also varied with sediment addition. Moreover, nitrogen released from the decomposition of water hyacinth and hydrilla were mainly NH 3 -N and organic nitrogen while those from cattail litter included organic nitrogen and NO 3 - -N. After the decomposition, the average carbon to nitrogen ratio (C/N) in the receiving water was about 2.6 (water hyacinth), 5.3 (hydrilla) and 20.3 (cattail). Therefore, cattail litter might be a potential plant carbon source for denitrification in ecological system of a constructed wetland. Copyright © 2017 Elsevier Ltd. All rights reserved.

Present state of boron-carbon thermoelectric materials

NASA Technical Reports Server (NTRS)

Elsner, N. B.; Reynolds, G. H.

1983-01-01

Boron-carbon p-type thermoelectric materials show promise for use in advanced thermal-to-electric space power conversion systems. Here, recent data on the thermoelectric properties of boron-carbon materials, such as B9C, B13C2, B15C2, and B4C, are reviewed. In particular, attention is given to the effect of the compositional homogeneity and residual impurity content on the Seeback coefficient, electrical resistivity, and thermal conductivity of these materials. The effect of carbon content for a given level of impurity and degree of homogeneity is also discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jacobs, G.K.

ORNL, through The Consortium for Research on Enhancing Carbon Sequestration in Terrestrial Ecosystems (CSiTE), collaborated with The Village Botanica, Inc. (VB) on a project investigating carbon sequestration in soils and commercial products from a new sustainable crop developed from perennial Hibiscus spp. Over 500 pre-treated samples were analyzed for soil carbon content. ORNL helped design a sampling scheme for soils during the planting phase of the project. Samples were collected and prepared by VB and analyzed for carbon content by ORNL. The project did not progress to a Phase II proposal because VB declined to prepare the required proposal.

Fossilized microorganisms associated with zeolite-carbonate interfaces in sub-seafloor hydrothermal environments.

PubMed

Ivarsson, M; Lindblom, S; Broman, C; Holm, N G

2008-03-01

In this paper we describe carbon-rich filamentous structures observed in association with the zeolite mineral phillipsite from sub-seafloor samples drilled and collected during the Ocean Drilling Program (ODP) Leg 197 at the Emperor Seamounts. The filamentous structures are approximately 5 microm thick and approximately 100-200 microm in length. They are found attached to phillipsite surfaces in veins and entombed in vein-filling carbonates. The carbon content of the filaments ranges between approximately 10 wt% C and 55 wt% C. They further bind to propidium iodide (PI), which is a dye that binds to damaged cell membranes and remnants of DNA. Carbon-rich globular microstructures, 1-2 microm in diameter, are also found associated with the phillipsite surfaces as well as within wedge-shaped cavities in phillipsite assemblages. The globules have a carbon content that range between approximately 5 wt% C and 55 wt% C and they bind to PI. Ordinary globular iron oxides found throughout the samples differ in that they contain no carbon and do not bind to the dye PI. The carbon-rich globules are mostly concentrated to a film-like structure that is attached to the phillipsite surfaces. This film has a carbon content that ranges between approximately 25 wt% C and 75 wt% C and partially binds to PI. EDS analyses show that the carbon in all structures described are not associated with calcium and therefore not bound in carbonates. The carbon content and the binding to PI may indicate that the filamentous structures could represent fossilized filamentous microorganisms, the globules could represent fossilized microbial cells and the film-like structures could represent a microbially produced biofilm. Our results extend the knowledge of possible habitable niches for a deep biosphere in sub-seafloor environments and suggests, as phillipsite is one of the most common zeolite mineral in volcanic rocks of the oceanic crust, that it could be a common feature in the oceanic crust elsewhere.

Formation and preservation of pedogenic carbonates in South India, links with paleo-monsoon and pedological conditions: Clues from Sr isotopes, U-Th series and REEs

NASA Astrophysics Data System (ADS)

Violette, Aurélie; Riotte, Jean; Braun, Jean-Jacques; Oliva, Priscia; Marechal, Jean-Christophe; Sekhar, M.; Jeandel, Catherine; Subramanian, S.; Prunier, Jonathan; Barbiero, Laurent; Dupre, Bernard

2010-12-01

The influence of the pedogenic and climatic contexts on the formation and preservation of pedogenic carbonates in a climosequence in the Western Ghats (Karnataka Plateau, South West India) has been studied. Along the climosequence, the current mean annual rainfall (MAR) varies within a 80 km transect from 6000 mm at the edge of the Plateau to 500 mm inland. Pedogenic carbonates occur in the MAR range of 500-1200 mm. In the semi-arid zone (MAR: 500-900 mm), carbonates occur (i) as thick hardpan calcretes on pediment slopes and (ii) as nodular horizons in polygenic black soils (i.e. vertisols). In the sub-humid zone (MAR: 900-1500 mm), pedogenic carbonates are disseminated in the black soil matrices either as loose, irregular and friable nodules of millimetric size or as indurated botryoidal nodules of centimetric to pluricentimetric size. They also occur at the top layers of the saprolite either as disseminated pluricentimetric indurated nodules or carbonate-cemented lumps of centimetric to decimetric size. Chemical and isotopic ( 87Sr/ 86Sr) compositions of the carbonate fraction were determined after leaching with 0.25 N HCl. The corresponding residual fractions containing both primary minerals and authigenic clays were digested separately and analyzed. The trend defined by the 87Sr/ 86Sr signatures of both labile carbonate fractions and corresponding residual fractions indicates that a part of the labile carbonate fraction is genetically linked to the local soil composition. Considering the residual fraction of each sample as the most likely lithogenic source of Ca in carbonates, it is estimated that from 24% to 82% (55% on average) of Ca is derived from local bedrock weathering, leading to a consumption of an equivalent proportion of atmospheric CO 2. These values indicate that climatic conditions were humid enough to allow silicate weathering: MAR at the time of carbonate formation likely ranged from 400 to 700 mm, which is 2- to 3-fold less than the current MAR at these locations. The Sr, U and Mg contents and the ( 234U/ 238U) activity ratio in the labile carbonate fraction help to understand the conditions of carbonate formation. The relatively high concentrations of Sr, U and Mg in black soil carbonates may indicate fast growth and accumulation compared to carbonates in saprolite, possibly due to a better confinement of the pore waters which is supported by their high ( 234U/ 238U) signatures, and/or to higher content of dissolved carbonates in the pore waters. The occurrence of Ce, Mn and Fe oxides in the cracks of carbonate reflects the existence of relatively humid periods after carbonate formation. The carbonate ages determined by the U-Th method range from 1.33 ± 0.84 kyr to 7.5 ± 2.7 kyr and to a cluster of five ages around 20 kyr, i.e. the Last Glacial Maximum period. The young occurrences are only located in the black soils, which therefore constitute sensitive environments for trapping and retaining atmospheric CO 2 even on short time scales. The maximum age of carbonates depends on their location in the climatic gradient: from about 20 kyr for centimetric nodules at Mule Hole (MAR = 1100 mm/yr) to 200 kyr for the calcrete at Gundlupet (MAR = 700 mm/yr, Durand et al., 2007). The intensity of rainfall during wet periods would indeed control the lifetime of pedogenic carbonates and thus the duration of inorganic carbon storage in soils.

Characteristics of Sodium Polyacrylate/Nano-Sized Carbon Hydrogel for Biomedical Patch.

PubMed

Park, Jong-Kyu; Seo, Sun-Kyo; Cho, Seungkwan; Kim, Han-Sung; Lee, Chi-Hwan

2018-03-01

Conductive hydrogels were prepared for biomedical patch in order to improve the electrical conductivity. Sodium polyacrylate and nano-sized carbon were mixed and fabricated by aqueous solution gelation process in various contents of nano-sized carbon with 0.1, 0.5, 1.0 and 2.0 wt%. Sodium polyacrylate/nano-sized carbon conductive hydrogels were investigated by molecular structure, surface morphology and electrical conductivity. The conductivity of the hydrogel/nano-sized carbon conductive hydrogel proved to be 10% higher than conductive hydrogel without nano-sized carbon. However, it was founded that conductive hydrogels with nano-sized carbon content from 0.5 up to 2.0 wt% were remarkably decreased. This may be due to the non-uniform distribution of nano-sized carbon, resulting from agglomerates of nano-sized carbon. The developed hydrogel is intended for use in the medical and cosmetic fields that is applicable to supply micro-current from device to human body.

Characterization of adsorption and degradation of diuron in carbonatic and noncarbonatic soils.

PubMed

Kasozi, Gabriel N; Nkedi-Kizza, Peter; Agyin-Birikorang, Sampson; Zimmerman, Andrew R

2010-01-27

The adsorption and degradation of the pesticide diuron in carbonatic and noncarbonatic soils were investigated to better understand the fate and transport of diuron in the environment. Batch adsorption experiments yielded isotherms that were well-described by the linear model. Adsorption coefficients normalized to soil organic carbon content (K(oc)) were lowest for carbonatic soils, averaging 259 +/- 48 (95% CI), 558 +/- 109, 973 +/- 156, and 2090 +/- 1054 for carbonatic soils, Histosols, Oxisols, and Spodosols, respectively. In addition, marl-carbonatic soils had much lower K(oc) values (197 +/- 27) than nonmarl-carbonatic soils. Diuron degradation data fit a first-order reaction kinetics model, yielding half-lives in soils ranging from 40 to 267 days. There was no significant difference between the average diuron degradation rate coefficients of each of the soil groups studied. Given the low adsorption capacity of carbonatic soils, it may be advisable to lower herbicide application rates in agricultural regions with carbonatic soils such as southern Florida to protect aquatic ecosystems and water quality.

Geochemistry of polycyclic aromatic hydrocarbons in the bottom sediments of the eastern Arctic shelf

NASA Astrophysics Data System (ADS)

Petrova, V. I.; Batova, G. I.; Kursheva, A. V.; Litvinenko, I. V.; Savinov, V. M.; Savinova, T. N.

2008-04-01

Sources and pathways of supply of polycyclic aromatic hydrocarbons (PAH) in the surface sediments of the Laptev and East Siberian seas were identified based on an analysis of the lithological-geochemical characteristics and distribution of organic matter (OM). The distribution of organic carbon, humic acids, bitumoids, and hydrocarbons demonstrates the determining role of the riverine runoff in the formation of the recent sediments. The total average content of PAH in the sediments of this region approximates 37 ng/g, not exceeding 80 ng/g of dry sediment. The biogenic components of the PAH (alkylphenanthrenes, alkylchrysenes, perylene) dominate in the estuarine-shelf and coastal-shelf sediments enriched with plant detritus and significantly decrease in the pelagic zone. The anthropogenic influence is observed in sediments of the port of Tiksi, where the total content of PAH with dominant pyrogenic components is two orders of magnitude higher as compared with the background values in the study region.

Evidence for Biomass Burning from 14C and 13C/12C Measurements at T-0 and T-1 during MILAGRO.

NASA Astrophysics Data System (ADS)

Gaffney, J. S.; Marley, N. A.; Tackett, M. J.; Sturchio, N. C.; Heraty, L. J.; Martinez, N.; Hardy, K.; Guilderson, T.

2007-12-01

Both stable carbon isotopic and radiocarbon characterizations of aerosols can yield important information regarding the sources of carbonaceous aerosols in urban and regional environments. Biomass derived materials are labeled due to their recent photochemical activity in radiocarbon and vary depending upon the photochemical pathway (either C-4 or C-3) in stable carbon-13 content. C-4 being enriched over C-3. During the MILAGRO campaign, quartz filter samples were taken at 12 hour intervals from 5 am to 5 pm (day) and from 5 pm to 5 am (night) during the month of March 2006. These samples were taken at the two super-sites, T-0 (Instituto Mexicano de Petroleo in Mexico City) and T-1 (Universidad Technologica de Tecamac, State of Mexico). The total carbon content was analyzed for stable carbon isotopic composition as well as for radiocarbon. Stable isotope mass spectroscopy was used to determine the carbon-13 to carbon-12 isotopic ratios on carbon dioxide. The carbon dioxide was then converted to graphite for analysis by accelerator mass spectrometry at the Center for Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory. Results are presented for the carbon-13 content relative to the PDB standard and radiocarbon is given relative to recent carbon. The results for total radiocarbon content show that the carbonaceous aerosol content in Mexico City has more than half of the carbon coming from biomass derived sources. These can include inflow of biomass burning aerosols into the T-0 site as well as the input from local burning of biofuels and trash containing biomass derived materials (paper, boxes, etc.). Data also indicate that at the T-1 site biomass burning of C-4 grasses appears to be significant in that the carbon-13 values observed are enriched. Also at T-1 the radiocarbon levels are also found to be slightly higher indicating regional biomass burning as a significant contributor to aerosol carbon in the 0.1 to 1.0 micron size fraction. Some day and night differences were observed that indicate secondary organic aerosols are contributing and that a significant fraction of these aerosols are biomass derived. Further analyses of organic carbon and elemental carbon fractions are underway. This work was performed as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX- Mex) under the support of the Atmospheric Science Program. This research was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-07ER64328.

40 CFR 600.509-12 - Voluntary submission of additional data.

Code of Federal Regulations, 2013 CFR

2013-07-01

... (CONTINUED) ENERGY POLICY FUEL ECONOMY AND GREENHOUSE GAS EXHAUST EMISSIONS OF MOTOR VEHICLES Procedures for Determining Manufacturer's Average Fuel Economy and Manufacturer's Average Carbon-Related Exhaust Emissions... addition to the data required by the Administrator. (b) Additional fuel economy and carbon-related exhaust...

40 CFR 600.509-12 - Voluntary submission of additional data.

Code of Federal Regulations, 2012 CFR

2012-07-01

... (CONTINUED) ENERGY POLICY FUEL ECONOMY AND GREENHOUSE GAS EXHAUST EMISSIONS OF MOTOR VEHICLES Procedures for Determining Manufacturer's Average Fuel Economy and Manufacturer's Average Carbon-Related Exhaust Emissions... addition to the data required by the Administrator. (b) Additional fuel economy and carbon-related exhaust...

Evidence of subduction and crust-mantle mixing from a single diamond

NASA Astrophysics Data System (ADS)

Schulze, Daniel J.; Harte, Ben; Valley, John W.; Channer, Dominic M. DeR.

2004-09-01

Cathodoluminescence (CL) imaging of polished sections of a diamond from the Guaniamo region of Venezuela suggests a history of the diamond involving two periods of growth separated by a period of resorption and possibly brittle deformation. In situ electron probe analysis of multiple eclogitic garnet inclusions reveals a correlation between garnet composition and location in the stone. An early-formed garnet in the diamond core has higher Ca/(Ca+Mg) and lower Mg/(Mg+Fe) values than later garnets associated with the second period of diamond growth. This variation conforms to an extensive trend of variation in the suite of eclogitic garnets extracted from Venezuelan diamonds. The diamond is zoned in carbon isotope composition (in situ secondary ion mass spectrometry, SIMS, data). The core compositions ( δ13C PDB), corresponding to the first stage of growth, average -17.7‰. The second period of growth is apparently in two sub-sets of CL zones with mean values of -13.0‰ and -7.9‰. Nitrogen contents of diamond are low (30-300 atomic ppm) and do not correlate with carbon isotope composition. Oxygen isotope ratios of the garnet inclusions are elevated substantially above those expected for "common mantle"; δ18O VSMOW of early garnet is approximately +10.5‰ and two late garnets average +8.8‰. The evolutionary trend of magnesium enrichment in garnet is unlikely to represent igneous fractionation. The stable isotope data are consistent with diamond formation in subducted meta-basic rocks that had interacted with sea water at low temperatures at or near the sea floor and contained a substantial biogenic carbon component. During or following subduction, diamonds continued to form in an evolving system that was progressively modified by interaction with mantle material.

Thermal/optical methods for elemental carbon quantification in soils and urban dusts: equivalence of different analysis protocols.

PubMed

Han, Yongming; Chen, Antony; Cao, Junji; Fung, Kochy; Ho, Fai; Yan, Beizhan; Zhan, Changlin; Liu, Suixin; Wei, Chong; An, Zhisheng

2013-01-01

Quantifying elemental carbon (EC) content in geological samples is challenging due to interferences of crustal, salt, and organic material. Thermal/optical analysis, combined with acid pretreatment, represents a feasible approach. However, the consistency of various thermal/optical analysis protocols for this type of samples has never been examined. In this study, urban street dust and soil samples from Baoji, China were pretreated with acids and analyzed with four thermal/optical protocols to investigate how analytical conditions and optical correction affect EC measurement. The EC values measured with reflectance correction (ECR) were found always higher and less sensitive to temperature program than the EC values measured with transmittance correction (ECT). A high-temperature method with extended heating times (STN120) showed the highest ECT/ECR ratio (0.86) while a low-temperature protocol (IMPROVE-550), with heating time adjusted for sample loading, showed the lowest (0.53). STN ECT was higher than IMPROVE ECT, in contrast to results from aerosol samples. A higher peak inert-mode temperature and extended heating times can elevate ECT/ECR ratios for pretreated geological samples by promoting pyrolyzed organic carbon (PyOC) removal over EC under trace levels of oxygen. Considering that PyOC within filter increases ECR while decreases ECT from the actual EC levels, simultaneous ECR and ECT measurements would constrain the range of EC loading and provide information on method performance. Further testing with standard reference materials of common environmental matrices supports the findings. Char and soot fractions of EC can be further separated using the IMPROVE protocol. The char/soot ratio was lower in street dusts (2.2 on average) than in soils (5.2 on average), most likely reflecting motor vehicle emissions. The soot concentrations agreed with EC from CTO-375, a pure thermal method.

Blue carbon content of mangrove vegetation in Subang district

NASA Astrophysics Data System (ADS)

Nurruhwati, I.; Purwita, S. D.; Sunarto; Zahidah

2018-04-01

The purpose of this research was to know the carbon content of mangrove parts such as leave, stems and roots and to know its ability to absorb carbondioxide (CO2). The research was conducted in 27th April until 16th May 2017 in Blanakan Village, Langensari Village and Jayamukti Village. The samples are dried at Pilotplane Laboratory Faculty of Industrial Engineering Padjadjaran University. The method in this research is explorative survey method. The results showed that there were two dominant mangroves species in three research stations, they are Avicennia marina and Rhizophora mucronata. Index of Important value of each mangrove type on the three stations in the medium criterion with a range of values is 106,86 %- 193,13 %. The highest carbon content was found in Rhizophora mucronata at station 1 (93,43 %) which was equivalent with 342,87 % absorption of CO2 which was The lowest carbon content was in Avicennia marina at station 1 (67,49 %) which was equivalent with 247,70 % absorption of CO2.

Light environment and leaf characteristics affect distribution of Corythuca arcuata (Hemiptera: Tingidae).

PubMed

Barber, Nicholas A

2010-04-01

Insect herbivore abundances on host plants are influenced by both plant traits and the physical environment in which that plant grows. This study examined the role of the physical light environment and foliage characteristics in determining abundance of the lacebug Corythuca arcuata Say (Hemiptera: Tingidae) on Quercus alba L. I censused adult C. arcuata across a growing season, quantified leaf characteristics, and measured canopy cover over understory branches of mature Q. alba. Using an information-theoretic approach, a priori hypotheses of the relationship between light, plant traits, and C. arcuata abundance was evaluated. Abundance was best predicted by light environment and carbon content. Adult C. arcuata prefer trees growing under an open canopy and trees with low carbon content; abundance also positively correlated with leaf water content. Although carbon and water did not vary with light in this study, low carbon and high water content are often associated with shadier conditions, suggesting that C. arcuata faces a trade-off between preferences for physical habitat conditions and host plant characteristics.