Dataset Information

?(13)C-CH4 reveals CH4 variations over oceans from mid-latitudes to the Arctic.

ABSTRACT: The biogeochemical cycles of CH4 over oceans are poorly understood, especially over the Arctic Ocean. Here we report atmospheric CH4 levels together with ?(13)C-CH4 from offshore China (31°N) to the central Arctic Ocean (up to 87°N) from July to September 2012. CH4 concentrations and ?(13)C-CH4 displayed temporal and spatial variation ranging from 1.65 to 2.63 ppm, and from -50.34% to -44.94% (mean value: -48.55 ± 0.84%), respectively. Changes in CH4 with latitude were linked to the decreasing input of enriched ?(13)C and chemical oxidation by both OH and Cl radicals as indicated by variation of ?(13)C. There were complex mixing sources outside and inside the Arctic Ocean. A keeling plot showed the dominant influence by hydrate gas in the Nordic Sea region, while the long range transport of wetland emissions were one of potentially important sources in the central Arctic Ocean. Experiments comparing sunlight and darkness indicate that microbes may also play an important role in regional variations.

SUBMITTER: Yu J

PROVIDER: S-EPMC4555175 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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δ(13)C-CH4 reveals CH4 variations over oceans from mid-latitudes to the Arctic.

Yu Juan J Xie Zhouqing Z Sun Liguang L Kang Hui H He Pengzhen P Xing Guangxi G

Scientific reports 20150901

The biogeochemical cycles of CH4 over oceans are poorly understood, especially over the Arctic Ocean. Here we report atmospheric CH4 levels together with δ(13)C-CH4 from offshore China (31°N) to the central Arctic Ocean (up to 87°N) from July to September 2012. CH4 concentrations and δ(13)C-CH4 displayed temporal and spatial variation ranging from 1.65 to 2.63 ppm, and from -50.34% to -44.94% (mean value: -48.55 ± 0.84%), respectively. Changes in CH4 with latitude were linked to the decreasing i ...[more]

PMID: 26323236

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Project description:Although plant species originated from Arctic regions commonly grow in alpine habitats at mid-latitudes, some populations of these species exist also in some specific habitats below the treeline. Local populations at lower elevations may have different origins, ploidy levels, mating systems and/or morphological traits from alpine populations, but comparative studies between alpine and low-elevation populations are scarce. We aimed to reveal the ecological and genetic differentiations between higher and lower populations of Vaccinium vitis-idaea in Hokkaido, northern Japan by comparing 22 populations growing in diverse environments. We analysed the ploidy level of individual populations using flow cytometry. Genetic differentiation among populations, and genetic diversity within populations were calculated using microsatellite markers. Fruit and seed production were recorded under natural conditions, and a pollination experiment was conducted to reveal the variations in mating system across populations. Furthermore, we compared shoot growth and leaf characteristics among populations. Most of the low-elevation populations were tetraploid, whereas all but one of the alpine populations were diploid. Tetraploid populations were clearly differentiated from diploid populations. Some tetraploid populations formed huge clonal patches but genetic diversity was higher in tetraploids than in diploids. Alpine diploids were self-incompatible and produced more seeds per fruit than tetraploid populations. In contrast, tetraploids showed high self-compatibility. Leaf size and foliar production were greater in tetraploid populations. Our results indicate that the genetic compositions of low-elevation tetraploid populations are different from those of alpine diploid populations. Most populations at lower elevations contained unique ecotypes suited to persistence in isolated situations. Local, low-elevation populations of typical alpine species maintain ecologically and genetically specific characteristics and could be valuable in terms of evolutionary and conservation biology. The present study demonstrates the biological importance of small and isolated populations at the edges of species distribution.

Project description:ObjectivesTo examine associations between three commonly used objective measures of physical capability assessed at age 53 and a composite score of these measures and all cause mortality; to investigate whether being unable to perform these tests is associated with mortality.DesignCohort study.SettingMRC National Survey of Health and Development in England, Scotland, and Wales.Participants1355 men and 1411 women with data on physical capability at age 53 who were linked to the National Health Service (NHS) central register for death notification.Main outcome measureAll cause mortality between ages 53 (1999) and 66 (2012).ResultsFor each of the three measures of physical capability (grip strength, chair rise speed, and standing balance time) those participants unable to perform the test and those in the lowest performing fifth were found to have higher mortality rates than those in the highest fifth. Adjustment for baseline covariates partially attenuated associations but in fully adjusted models the main associations remained. For example, the fully adjusted hazard ratio of all cause mortality for the lowest compared with the highest fifth of a composite score of physical capability was 3.68 (95% confidence interval 2.03 to 6.68). Those people who could not perform any of the tests had considerably higher rates of death compared with those people able to perform all three tests (8.40, 4.35 to 16.23). When a series of models including different combinations of the measures were compared by using likelihood ratio tests, all three measures of physical capability were found to improve model fit, and a model including all three measures produced the highest estimate of predictive ability (Harrell's C index 0.71, 95% confidence interval 0.65 to 0.77). There was some evidence that standing balance time was more strongly associated with mortality than the other two measures.ConclusionsLower levels of physical capability at age 53 and inability to perform capability tests are associated with higher rates of mortality. Even at this relatively young age these measures identify groups of people who are less likely than others to achieve a long and healthy life.

Dataset Information

?(13)C-CH4 reveals CH4 variations over oceans from mid-latitudes to the Arctic.

Publications

δ(13)C-CH4 reveals CH4 variations over oceans from mid-latitudes to the Arctic.

Similar Datasets

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