δ13 Values of C4 Types in Grasses

1982 ◽  
Vol 9 (2) ◽  
pp. 139 ◽  
Author(s):  
PW Hattersley
Keyword(s):  
Sampling Bias ◽  
Individual Species ◽  
C4 Grasses ◽  
C4 Plant ◽  
Fractionation Process ◽  
Carbon Reduction ◽  
Tissue Equivalent ◽  
Suberized Lamella ◽  
The Difference ◽  
Intercellular Co2

δ13 values were determined for leaves of C4 grasses (Poaceae) of different photosynthetic types. For plants grown in the same environment at the same time, mean δ13 values for the three C4 types were: NADP-ME-type, - 11.350 � 0.13 s.e. (11 spp.); PCK-type, - 11.950 � 0.19 s.e. (11 spp.); and NAD-ME-type, -12.70 � 0.21 s.e. (9 spp.). Although there is some overlap between the values for individual species of the three groups, the difference between any two means is highly significant [P(t) < 0.01] and is not due to taxonomic sampling bias at the subfamily level. The differences in means may suggest that C4 types differ in rates of leakage of CO2 and HCO3- from PCR tissue ('photosynthetic carbon reduction' tissue: equivalent to 'Kranz' tissue), and/or, using Farquhar's (Appendix) expression for plant δ values, that C4 types differ in their average intercellular CO2 concentrations (c1). It is also possible that differences between C4 types exist in some other, unknown, leaf fractionation process. Apoplastic CO2 leakage from PCR tissue in NAD-ME-type C4 grasses, which do not possess a PCR 'suberized lamella' as found in NADP-ME- type and PCK-type C4 grasses, may give these species the most negative δ13 values. Expressions for C4 plant δ13 values, and a model for the δ13 values of CO2 and HCO3- in various pools and fluxes in C4 plant leaves, are given.

Letters to the Editor

PEDIATRICS ◽  
1971 ◽  
Vol 47 (3) ◽  
pp. 630-630
Author(s):  
Alfred Yankauer
Keyword(s):  
United States ◽  
The Netherlands ◽  
Sampling Bias ◽  
The United States ◽  
Vital Statistics ◽  
Letters To The Editor ◽  
Medical Centers ◽  
Reporting Requirements ◽  
The Difference

The generalizations which Dr. Nichols has made (or inferred) by applying his (incorrect and incomplete) definitions to data from Galveston and Philadelphia are affected by an enormous sampling bias. How many other places in the United States which are not medical centers report the outcomes of pregnancy in the same way? Perhaps there is even more "under-reporting" (as Dr. Nichols defines it) in the U.S.A. as a whole than in the Netherlands as a whole in spite of certain differences in "official" reporting requirements (even though the difference Dr. Nichols specifies no longer holds)? Furthermore, the Galveston-Philadelphia data Dr. Nichols quotes are not those reported to the Vital Statistics Divisions of the cities of Philadelphia and Galveston.

scholarly journals Can ‘loss and damage’ carry the load?

2018 ◽  
Vol 376 (2119) ◽  
pp. 20170070 ◽  
Author(s):  
Robert R. M. Verchick
Keyword(s):  
Paris Agreement ◽  
Climate Impacts ◽  
Point Of View ◽  
Residual Risk ◽  
Social Challenges ◽  
Carbon Reduction ◽  
Global Consensus ◽  
Loss And Damage ◽  
The Difference ◽  
Warming World

Even assuming a heroic rush towards carbon reduction and adaptation, some regions of the world will be hammered hard by climate impacts. Thus, a global consensus now sees the need for a supplemental plan to deal with the kind of harms that cannot be avoided—what Parties call ‘loss and damage’. For a loss-and-damage plan to work, it must be capable of carrying the load, the load being whatever minimal standards that morality and political consensus require. But if residual risk climbs too high, it will fall short of even the most basic expectations. The Paris Agreement calls for holding the rise in global average temperature to ‘well below 2°C above pre-industrial levels’, while working to limit the increase to 1.5°C. How much difference is in that half-degree? From the point of view of residual risk, quite a lot. According to a 2016 study published by the European Geosciences Union, a jump from 1.5°C to 2°C could produce outsize impacts, particularly in tropical latitudes. That difference could mark the line between a plan that is politically and morally defensible and one that is not. At the very least, the difference is enough to inform the design and expectations of any future plan. This article is part of the theme issue ‘The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels’.

Reproductive behaviour and cross-mating of two closely related pygmy squids Idiosepius biserialis and Idiosepius thailandicus (Cephalopoda: Idiosepiidae)

2008 ◽  
Vol 88 (5) ◽  
pp. 987-993 ◽  
Author(s):  
Jaruwat Nabhitabhata ◽  
Jitima Suwanamala
Keyword(s):  
Reproductive Behaviour ◽  
Morphological Characters ◽  
Andaman Sea ◽  
Individual Species ◽  
Gulf Of Thailand ◽  
Separate Species ◽  
Behavioural Patterns ◽  
Sea Grass ◽  
In Captivity ◽  
The Difference

Idiosepius biserialis and Idiosepius thailandicus have been previously described as separate species although the difference in morphological characters is only the arrangement of pegs in tentacular-club suckers. The former species inhabits sea grass beds in the Andaman Sea of Thailand. The latter species inhabits mangroves in the eastern Gulf of Thailand. The present study of reproductive behaviour, mating, and spawning of the two species in captivity demonstrated that they are closely related. Copulation was performed using tentacles by the male for fixation of spermatophores at the buccal region of the female. Behavioural patterns were distinguished based on the hovering and adhering positions of each sex. Cross-mating between two species was initiated and observed, yielding fertilized eggs which developed to the organogenesis stage. Reproductive behaviour of crossed pairs was similar to those of individual species. This study revealed that the two ‘species’ are not reproductively isolated.

Manufacturing Technique and Property Evaluations of Protective Textiles

2013 ◽  
Vol 457-458 ◽  
pp. 375-378
Author(s):  
Ching Wen Lou ◽  
Ting Ting Li ◽  
Mei Chen Lin ◽  
Jan Yi Lin ◽  
Jia Horng Lin
Keyword(s):  
Carbon Dioxide ◽  
Impact Strength ◽  
Carbon Dioxide Emission ◽  
High Strength ◽  
Puncture Resistance ◽  
Carbon Reduction ◽  
Nonwoven Fabrics ◽  
Constant Rate ◽  
The Difference ◽  
Protective Textiles

Global warming increases each day and causes people to pay more attention to the reduction of carbon dioxide emission in order to mitigate the increase in temperature. Reducing, reusing, and recycling can effectively reduce the emission of carbon dioxide, to attain goals of energy conservation and carbon reduction. This study aims to explore the difference in the punch resistance and impact strength between the polyethylene terephthalate (PET) nonwoven fabrics and PET/TPU honeycomb grid/PET (P/T/P) composites. Recycle PET, high strength PET, and low melting PET are made into PET nonwoven fabrics, two layers of which are laminated with a TPU honeycomb grid, the interlayer, to form P/T/P composites. The constant rate puncture resistance, dynamic puncture resistance, and impact strength of PET nonwoven fabrics and P/T/P composites are evaluated. The experiment results show that both the constant rate and dynamic puncture resistances of P/T/P composites are lower than those of PET nonwoven fabrics.

The magnitude of diurnal variation in carbon isotopic composition of leaf dark respired CO2 correlates with the difference between δ13C of leaf and root material

2010 ◽  
Vol 37 (9) ◽  
pp. 849 ◽  
Author(s):  
Frederik Wegener ◽  
Wolfram Beyschlag ◽  
Christiane Werner
Keyword(s):  
Carbon Allocation ◽  
Dark Respiration ◽  
Carbon Isotopic Composition ◽  
Krebs Cycle ◽  
Temporal Variations ◽  
Relative Activity ◽  
Water Soluble ◽  
Fractionation Process ◽  
Leaf Dark Respiration ◽  
The Difference

Spatial and temporal variations in δ13C of dark respired CO2 (δ13Cres) and total and water-soluble organic matter (WSOM) were analysed in four plant species. There was an increase in δ13Cres over the light period (measured 5 min after darkening) in leaves, whereas no distinct diurnal pattern was detected in roots. Furthermore, large differences in δ13Cres were found along the plant axis during day time. The amount of daily δ13Cres enrichment in leaves relative to the putative substrate (WSOM) varied largely between species (3.2–15.9‰), probably due to different carbon allocation strategies. Positional pyruvate labelling was used to detect whether variations in δ13Cres were related to changes in the relative activity of pyruvate dehydrogenase (PDH) and Krebs cycle (KC). The results indicate that one reason for the increase in δ13Cres in leaves during daylight is an increasing carbon flux through the PDH relative to the KC. Labelling experiments revealed no clear diurnal variations in PDH and KC activity in roots. Further, we found new evidence that the fractionation process that leads to the diurnal δ13C increase in leaf dark respiration is related to the well known 13C depletion of leaf material compared with heterotrophic tissues.

scholarly journals Aerosol absorption in global models from AeroCom Phase III

2021 ◽  
Author(s):  
Maria Sand ◽  
Bjørn H. Samset ◽  
Gunnar Myhre ◽  
Jonas Gliß ◽  
Susanne E. Bauer ◽  
...  
Keyword(s):  
Phase Ii ◽  
Climate Models ◽  
Global Climate ◽  
Global Climate Models ◽  
Phase Iii ◽  
Shortwave Radiation ◽  
Cloud Formation ◽  
Individual Species ◽  
Aerosol Absorption ◽  
The Difference

Abstract. Aerosol induced absorption of shortwave radiation can modify the climate through local atmospheric heating, which affects lapse rates, precipitation, and cloud formation. Presently, the total amount of such absorption is poorly constrained, and the main absorbing aerosol species (black carbon (BC), organic aerosols (OA) and mineral dust are diversely quantified in global climate models. As part of the third phase of the AeroCom model intercomparison initiative (AeroCom Phase III) we here document the distribution and magnitude of aerosol absorption in current global aerosols models and quantify the sources of intermodel spread. 15 models have provided total present-day absorption at 550 nm, and 11 of these models have provided absorption per absorbing species. The multi-model global annual mean total absorption aerosol optical depth (AAOD) is 0.0056 [0.0020 to 0.0097] (550 nm) with range given as the minimum and maximum model values. This is 31 % higher compared to 0.0042 [0.0021 to 0.0076] in AeroCom Phase II, but the difference/increase is within one standard deviation which in this study is 0.0024 (0.0019 in Phase II). The models show considerable diversity in absorption. Of the summed component AAOD, 57 % (range 34–84 %) is estimated to be due to BC, 30 % (12–49 %) is due to dust and 14 % (4–49 %) is due to OA, however the components are not entirely independent. Models with the lowest BC absorption tend to have the highest OA absorption, which illustrates the complexities in separating the species. The geographical distribution of AAOD between the models varies greatly and reflects the spread in global mean AAOD and in the relative contributions from individual species. The optical properties of BC are recognized as a large source of uncertainty. The model mean BC mass absorption coefficient (MACBC) value is 9.8 [3.1 to 16.6] m2 g−1 (550 nm). Observed MAC values from various locations range between 5.7–20.0 m2 g−1 (550 nm). Compared to retrievals of AAOD and absorption Ångstrøm exponent (AAE) from ground-based observations from the Aerosol Robotic Network (AERONET) stations, most models underestimate total AAOD and AAE. The difference in spectral dependency between the models is striking.

scholarly journals Validation of Aura-OMI QA4ECV NO<sub>2</sub> Climate Data Records with ground-based DOAS networks: role of measurement and comparison uncertainties

2020 ◽  
Author(s):  
Steven Compernolle ◽  
Tijl Verhoelst ◽  
Gaia Pinardi ◽  
José Granville ◽  
Daan Hubert ◽  
...  
Keyword(s):  
Scattered Light ◽  
A Priori ◽  
Sampling Bias ◽  
Climate Data ◽  
Vertical Column ◽  
Standard Data ◽  
Vertical Column Density ◽  
High Pollution ◽  
The Difference

Abstract. The QA4ECV version 1.1 stratospheric and tropospheric NO2 vertical column density (VCD) climate data records (CDR) from the satellite sensor OMI are validated, using NDACC zenith scattered light DOAS (ZSL-DOAS) and Multi Axis-DOAS (MAX-DOAS) data as a reference. The QA4ECV OMI stratospheric VCD have a small bias of ~ 0.2 Pmolec cm-2 (5–10 %) and a dispersion of 0.2 to 1 Pmolec cm-2 with respect to the ZSL-DOAS measurements. QA4ECV tropospheric VCD observations from OMI are restricted to near-cloud-free scenes, leading to a negative sampling bias (with respect to the unrestricted scene ensemble) of a few Pmolec cm-2 up to −10 Pmolec cm-2 (−40 %) in one extreme high-pollution case. QA4ECV OMI tropospheric VCD has a negative bias with respect to the MAX-DOAS data (−1 to −4 Pmolec cm-2), a feature also found for the OMI OMNO2 standard data product. The tropospheric VCD discrepancies between satellite and ground-based data exceed by far the combined measurement uncertainties. Depending on the site, part of the discrepancy can be attributed to a combination of comparison errors (notably horizontal smoothing difference error), measurement/retrieval errors related to clouds and aerosols, and to the difference in vertical smoothing and a priori profile assumptions.

scholarly journals Validation of Aura-OMI QA4ECV NO<sub>2</sub> climate data records with ground-based DOAS networks: the role of measurement and comparison uncertainties

2020 ◽  
Vol 20 (13) ◽  
pp. 8017-8045 ◽  
Author(s):  
Steven Compernolle ◽  
Tijl Verhoelst ◽  
Gaia Pinardi ◽  
José Granville ◽  
Daan Hubert ◽  
...  
Keyword(s):  
Scattered Light ◽  
A Priori ◽  
Sampling Bias ◽  
Atmospheric Composition ◽  
Optical Absorption Spectroscopy ◽  
Climate Data ◽  
Ozone Monitoring Instrument ◽  
Vertical Column ◽  
Standard Data ◽  
The Difference

Abstract. The QA4ECV (Quality Assurance for Essential Climate Variables) version 1.1 stratospheric and tropospheric NO2 vertical column density (VCD) climate data records (CDRs) from the OMI (Ozone Monitoring Instrument) satellite sensor are validated using NDACC (Network for the Detection of Atmospheric Composition Change) zenith-scattered light differential optical absorption spectroscopy (ZSL-DOAS) and multi-axis DOAS (MAX-DOAS) data as a reference. The QA4ECV OMI stratospheric VCDs have a small bias of ∼0.2 Pmolec.cm-2 (5 %–10 %) and a dispersion of 0.2 to 1 Pmolec.cm-2 with respect to the ZSL-DOAS measurements. QA4ECV tropospheric VCD observations from OMI are restricted to near-cloud-free scenes, leading to a negative sampling bias (with respect to the unrestricted scene ensemble) of a few peta molecules per square centimetre (Pmolec.cm-2) up to −10 Pmolec.cm-2 (−40 %) in one extreme high-pollution case. The QA4ECV OMI tropospheric VCD has a negative bias with respect to the MAX-DOAS data (−1 to −4 Pmolec.cm-2), which is a feature also found for the OMI OMNO2 standard data product. The tropospheric VCD discrepancies between satellite measurements and ground-based data greatly exceed the combined measurement uncertainties. Depending on the site, part of the discrepancy can be attributed to a combination of comparison errors (notably horizontal smoothing difference error), measurement/retrieval errors related to clouds and aerosols, and the difference in vertical smoothing and a priori profile assumptions.

Managing arid zone natural resources in Australia for spatial and temporal variability - an approach from first principles

2008 ◽  
Vol 30 (1) ◽  
pp. 15 ◽  
Author(s):  
Mark Stafford Smith ◽  
Ryan R. J. McAllister
Keyword(s):  
Resource Management ◽  
Natural Resource Management ◽  
Natural Resource ◽  
First Principles ◽  
Regional Integration ◽  
Arid Zone ◽  
Individual Species ◽  
Spatial And Temporal Variability ◽  
Systematic Analysis ◽  
The Difference

Outback Australia is characterised by variability in its resource drivers, particularly and most fundamentally, rainfall. Its biota has adapted to cope with this variability. The key strategies taken by desert organisms (and their weaknesses) help to identify the likely impacts of natural resource management by pastoralists and others, and potential remedies for these impacts. The key strategies can be summarised as five individual species’ responses (ephemerals, in-situ persistents, refuging persistents, nomads and exploiters), plus four key emergent modes of organisation involving multiple species that contribute to species diversity (facilitation, self-organising communities, asynchronous and micro-allopatric co-existence). A key feature of the difference between the strategies is the form of a reserve, whether roots and social networks for Persistents, or propagules or movement networks for Ephemerals and Nomads. With temporally and spatially varying drivers of soil moisture inputs, many of these strategies and their variants can co-exist. While these basic strategies are well known, a systematic analysis from first principles helps to generalise our understanding of likely impacts of management, if this changes the pattern of variability or interrupts the process of allocation to reserves. Nine resulting ‘weak points’ are identified in the system, and the implications of these are discussed for natural resource management and policy aimed at production or conservation locally, or the regional integration of the two.

Grazing kangaroos act as local recyclers of energy on semiarid floodplains

2010 ◽  
Vol 58 (3) ◽  
pp. 145 ◽  
Author(s):  
Jordan Iles ◽  
Jeff Kelleway ◽  
Tsuyoshi Kobayashi ◽  
Debashish Mazumder ◽  
Lisa Knowles ◽  
...  
Keyword(s):  
Stable Carbon Isotope ◽  
C4 Grasses ◽  
Carbon Stable Isotope ◽  
Stable Carbon ◽  
Large Herbivores ◽  
Feeding Site ◽  
Isotope Signature ◽  
Close Study ◽  
The Difference ◽  
Study Sites

On Australian semiarid floodplains, large herbivores such as kangaroos have a role in the cycling of energy (carbon) through the mechanism of feeding and defaecation of vegetative material. The degree to which kangaroos are vectors of energy within this system is not fully understood. This study describes the stable carbon isotope signature of floodplain plants and kangaroo scats at two close study sites. Kangaroos were found to deposit scats that mirrored the forage composition at each particular feeding site. Scats were 3.94‰ higher in δ13C values at the site where C4 grasses were available, indicating that this grass contributed ~25–30% of the diet of these kangaroos. The difference in diet due to the relative availability of C3 and C4 forage, detectable in the carbon stable isotope signature of scats, is used to demonstrate that kangaroos are recycling and redistributing energy locally, rather than transporting it more broadly across the floodplain.

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