Rezumat articol ediţie STUDIA UNIVERSITATIS BABEŞ-BOLYAI

În partea de jos este prezentat rezumatul articolului selectat. Pentru revenire la cuprinsul ediţiei din care face parte acest articol, se accesează linkul din titlu. Pentru vizualizarea tuturor articolelor din arhivă la care este autor/coautor unul din autorii de mai jos, se accesează linkul din numele autorului.

 
       
         
    STUDIA GEOLOGIA - Ediţia nr.1 din 2007  
         
  Articol:   SPELEOTHEM CARBON ISOTOPES AND ECOSYSTEM CHANGES.

Autori:  JEFFREY A. DORALE. 		 
       
         
  Rezumat:  The carbon isotopic values (δ13C) of speleothem carbonate are related to the primary sources of carbon in the cave seepage water. These sources are soil carbon dioxide, sourced from root respiration and microbial respiration and tied indirectly to atmospheric carbon dioxide by photosynthesis, and carbonate bedrock. Timescales of major karst development are typically on the order of 104-106 years, implying that variations in speleothem δ 13C on shorter timescales could likely be due to changes in the soil carbon pool, which is tied to vegetation. C3 and C4 photosynthetic pathways produce large differences in the d13C values of plant tissue. C3 plants have δ 13C values averaging ca. –26‰, whereas C4 plants average ca. –12‰. C4 plants are typically warm-season grasses and a few herbs found in tropical and temperate grasslands, whereas C3 plants are mostly trees, shrubs, cool-season grasses, and most herbs. Within their ranges, both proportion and biomass of C4 plants in North American grasslands are highly correlated with mean annual temperature and less strongly correlated within mean annual precipitation.  
         
     
         
         
      Revenire la pagina precedentă