A SURVEY OF STABLE ISOTOPES IN MODERN SURFACE WATERS OF ICELAND

We present a study of spatial variation of stable isotope (δ¹⁸O and δD) values of surface waters from Iceland. A total of 68 lakes and rivers were sampled during an eight day period in May and June of 2004, and analyzed for δ¹⁸O and δD. The water values range in δ¹⁸O from –13.6 to –7.6‰ VSMOW and average –9.9‰. δD values range from –100.2 to –53.2‰ and average –70.9‰. The local surface water line calculated from this data is δD=7.90·δ¹⁸O + 7.36, with an R² value of 0.88. This slope is slightly higher than that of the local meteoric water line for this region, δD=7.21·δ¹⁸O + 0.75. δ¹⁸O values show a decreasing trend from southwest to northeast, and there is a weak correlation between δ¹⁸O values and elevation. Modern water isotope values can help to identify the origin and season of precipitation, as well as determine the effects of evaporation, water transport and recycling in a region. This information can better characterize how climate regimes affect surface water values. As well, a more thorough understanding of modern climate systems can aid in the interpretation of paleoclimatic proxy records from a given region. The data presented here provides a picture of modern water isotope variation for this region, that is temporally limited, but offers a basis for understanding local hydrological systems and insight into longer-term climate change.