Isotopic composition of river water across a continent

• The plot of slopes versus intercept from the plot of δ18O and δ2H of various locations are done giving new pattern.
• This new pattern is analyzed to arrive at a isotopic composition of precipitation to be on GMWL.
• The continent is divided on the basis of original isotopic composition to be taken as injected tracer (δ18O and δ2H).

Isotopic composition of water across United States is available and also baseline data prepared for more than 4800 samples (with depth and width-integrated stream samples) from 391 selected sites within USGS National Stream Quality Accounting Network (NASQAN). Data had been analyzed with respect to arrival at National Meteoric Water Line (NMWL). Large number of NMWL water samples has much lower slopes than 8 and intercepts ranging from +10 to −39. These lower slopes and intercepts need a re-look to ascertain coherent δ2H and δ18O across USA in precipitation. A method is worked out by plotting slopes versus intercepts on δ2H axis to arrive at the isotopic composition of water on GMWL and also to look the regional pattern that reflects the origin of vapour mass.