Articles written in Journal of Earth System Science

    • Water use efficiency of net primary production in global terrestrial ecosystems

      Lei Xia Fei Wang Xingmin Mu Kai Jin Wenyi Sun Peng Gao Guangju Zhao

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      The carbon and water cycles of terrestrial ecosystems, which are strongly coupled via water use efficiency (WUE), are influenced by global climate change. To explore the relationship between the carbon and water cycles and predict the effect of climate change on terrestrial ecosystems, it is necessary to study the WUE in global terrestrial ecosystems. In this study, the 13-year WUE (i.e., net primary production (NPP)/evapotranspiration (ET)) of global terrestrial ecosystems was calculated based on the Moderate Resolution Imaging Spectro-radiometer (MODIS) NPP (MOD17A3) and ET (MOD16A3) products from 2000 to 2012. The results indicate that the annual average WUE decreased but not significantly, and the 13-year mean value was 868.88 mg C m−2 mm−1. The variation trend of WUE value for each pixel differed greatly across the terrestrial ecosystems. A significant variation (𝑃 < 0.05) occurred in about 18.50% of the land surface. WUE was spatially distributed from 0 to 2541 mg C m−2 mm−1, and 58.78% of the WUE values were concentrated in the interval of 600–1200 mg C m−2 mm−1. The WUE increased from north to south in Africa and Oceania and from east to west in Europe and South America. Both latitudinal and longitudinal gradients existed in Asia and North America. The following trends in the WUE of different continents and Köppen–Geiger climates were observed: Europe (1129.71 mg C m−2 mm−1) > Oceania (1084.46 mg C m−2 mm−1) > Africa (893.51 mg C m−2 mm−1) > South America (893.07 mg C m−2 mm−1) > North America (870.79 mg C m−2 mm−1) > Asia (738.98 mg C m−2 mm−1) and warm temperate climates (1094 mg C m−2 mm−1) > snowy climates (862 mg C m−2 mm−1) > arid climates (785 mg C m−2 mm−1) > equatorial climates (732 mg C m−2 mm−1) > polar climates (435 mg C m−2 mm−1). Based on the WUE value and the present or future rainfall, the maximum carbon that fixed in one region may be theoretically calculated. Also, under the background of global climatic change, WUE may be regarded as an important reference for allotting CO2 emissions offsets and carbon transactions.

    • Substantiation of Reunion plume induced prolonged magmatic pulses (ca. 70.5–65.5 Ma) of the Deccan LIP in the Chhotanagpur Gneissic Complex, eastern India: Constraints from $^{40}\rm{Ar}/^{39}\rm{Ar}$ geochronology


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      This study presents $^{40}\rm{Ar}/^{39}\rm{Ar}$ geochronology on the mafic dykes emplaced in the Damodar valley Gondwana sedimentary basins of the Chhotanagpur Gneissic Complex (CGC) to authenticate prolonged mafic magmatic activities during Maastrichtian period. A couple of earlier and one new $^{40}\rm{Ar}/^{39}\rm{Ar}$ plateau ages, which range in age from ca. 70.5 to 65.5 Ma, suggest prolonged ($\sim$5 myr) magmatic activities in the CGC. These syn- and pre-Deccan LIP magmatic intrusive activities in the CGC are supposedly related to the Reunion mantle plume. The reported age of 70.5 $\pm$ 0.9 Ma of a NE-trending mafic dyke emplaced within the Raniganj basin could probably be the earliest record of the Reunion mantle plume activity in the Indian shield. A number of other early magmatic rocks, related to the Reunion mantle plume induced Deccan LIP event, are also recorded elsewhere in the Indian shield and supportive of prolonged magmatic activities. Finally, this study also provides a better constraint on the initiation and lateral extent of the Reunion mantle plume induced Deccan LIP.

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