The goal of this project is to develop a baseline of environmental isotopes to understand hydrologic functioning of surface and ground waters throughout the Commonwealth of Massachusetts. The ultimate product of this effort are spatial maps of isotopic composition of surface water and groundwater that will define the iso-scape in which we live.
We are grateful to the Massachusetts Environmental Trust for their support of this project. For more information about MET click here.
Sampling Area
This is a map of all of our current sampling sites across Massachusetts. We have more sampling data from surrounding states as well.
Through a combination of sampling efforts by numerous voluntary contributing organizations and the UMass Hydro Team, we have been able to create a water isotope database consisting of data from all over Massachusetts and much of the Northeast.
What are Isotopes?
Isotopes are elements that have different numbers of neutrons than protons. In the context of water (H2O) this means that the each of the two hydrogen atoms and the oxygen atom can have different numbers of neutrons associated with each elements protons. Differing neutron and proton numbers means different waters have different weights and can be lighter or heavier. Most isotopes follow an isotopic ratio–the more neutrons in on the hydrogen, the more neutrons on the oxygen and vice versa.
“The Polar Jet Stream.” Image: NOAA GFS
Extra-Tropical Storm: “Hurricane Irene.” NOAA. 26 August 2011.
What Do Different Isotopic Signatures in Water Tell Us?
Different isotopic signatures gives us information about the water. Depending on the weight of the water, the source of the water (extra-tropical versus arctic) or the age of the water (recently precipitated versus groundwater) can be inferred. For example, extra-tropical storm waters tend to have a heavier signature whereas Arctic waters tend to be slightly lighter. Precipitation is usually significantly heavier than than older water.
How do we Measure the Isotopic Signature?
We use a machine called the Picarro Cavity Ring Down Spectrometer L2120-I. This machine vaporizing the sample and then measures the wavelength absorption of the sample. This is then compared to the Vienna Standard Mean Ocean Water line. This line acts as a reference point as water switches from ocean to freshwater processes.
Why is this Research Important?
Most significantly, the breadth of this project allows us to track the response of watersheds to hydrologic events–whether that be major storms, or droughts. This will especially be significant as we climate change begins to take effect and more extreme weather events occur. Water isotope signatures are also useful in other environmental scenarios such as a tracer in contamination scenarios. This project is the first of its kind at the state level in the nation.