WIM no. 17 Spring 2020

מכון ויצמן למדע Sleuthing for the fingerprint of water Introducing Dr. Yael Kiro, groundwater detective G roundwater, seawater, ice, micro-droplets trapped in sediments, and evaporatedminerals like Dead Sea salts can carry a chemical signature that can be unlocked and readwith the sophisticated analytical tools being developed by scientists like Dr. Yael Kiro in the Department of Earth and Planetary Sciences. Dr. Kiro is a geochemist who uses radioactive isotopes and chemical clues to read the environmental record preserved in groundwater, lake sediments, ice cores, and coastal aquifers. As a PhD student at the Hebrew University of Jerusalem, Dr. Kiro focused her research on hydrology in the Dead Sea, and went on to develop a new concept for using radioactive isotopes to estimate the age of groundwater systems and to track the circulation of water in aquifers deep underground. Water is a precious commodity in the arid Middle East, and groundwater aquifers are a big part of Israel’s water equation. Dr. Kiro provides some of the tools needed to learn how much water is present in an aquifer, its salinity, and what kinds of minerals and pollutants are present. Being able to age and track samples of groundwater can provide data on how long an aquifer takes to circulate and recharge. This is vital information for politicians and planners as well as earth scientists. Reading rocks like a book Geologists and geochemists like Dr. Kiro can read layers of sedimentary rock like a book that reveals hundreds of thousands of years of history. Using 1,500 feet of core samples from the bottom of the Dead Sea, Dr. Kiro co-led an international study that showed evidence of two “mega” droughts from this geological record: one that began approximately 120,000 years ago, when average global temperatures rose about four degrees Fahrenheit, and another about 10,000 years ago, following the last ice age. In a recent study, Dr. Kiro helped compare the trace chemicals in the tiny pockets of saline fluids found in core samples drilled in the deepest floor of the Dead Sea. This gives scientists new insights into the Dead Sea during the last interglacial and glacial periods and some clues about changes in rainfall patterns at that time which might be relevant for the changes in store to Israel in the near geological future. The alarming rate of the Dead Sea’s shrinkage— about a meter per year—is a well-known and lamented phenomenon that is the result of water diversion projects, and industry pumping out the salty, profitable water for potash. It’s also the result Weizmann MAGAZINE New Scientists