We’re surrounded by a bunch of odd, but harmless, oxygen and hydrogen atoms. These atoms are isotopes, meaning that they have extra neutrons. Hydrogen-2 has one extra neutron and occurs about once per every 6800 hydrogen atoms in New England waters; oxygen-18 has two extra neutrons and occurs about once per every 500 oxygen atoms in New England waters. These isotopes are stable and are very useful for understanding how water moves in watersheds because some water sources have different amounts of these stable isotopes. For example, snow looks really different than rain with regards to oxygen and hydrogen isotopes.
My students, colleagues, and I are now engaged in measuring water isotopes from a number of water sources across New Hampshire and New England. The new cavity ring-down spectrometer, housed at the CFE, allows us to add measurement of water isotopes to projects that can benefit from understanding the details of water transport. In particular, making simultaneous measurements of water quality and water isotopes can help track sources of water pollution. Measurements of stable water isotopes had previously been isolated to research applications because of the high cost of laboratory instrumentation. However, new technology has brought the cost down to a fraction of previous expense, so I expect that water isotope measurements will become more accessible to watershed management applications.
So far, water stable isotope measurements from the CFE analyzer have been used for two Research Experience of Undergraduate projects at the Hubbard Brook Experimental Forest, one Environmental Science and policy M.S. project, one project studying groundwater-dependent ecosystems on the White Mountain National Forest, and aiding a volunteer monitoring group on the Israel River in northern New Hampshire. As we make more measurements across northern New England we gain context about what different water sources look like, allowing better interpretation of individual watershed dynamics. By improving our basic understanding of watershed hydrology with water isotopes, watershed management stands to become more effective and efficient.