Researchers at the University of Utah have delved into the sedimentary heart of the Great Salt Lake, unearthing a detailed chronicle of environmental shifts that extends some 8,000 years into the past. Through isotope analysis of lake bed sediments, scientists have now quantified how human activities have pushed the lake into unprecedented biogeochemical territory. As noted by At The U, the arrival of settlers and subsequent developments have altered the lake and its watershed on a scale unseen even over millennia.
According to Professor Gabriel Bowen, who steered the study, "Lakes are great integrators. They're a point of focus for water, for sediments, and also for carbon and nutrients," as per At The U. The Great Salt Lake, sensitive to both climate changes and anthropogenic factors, has undergone significant shifts in its climate and water inflow over its extensive history. The study, published in Geophysical Research Letters, sheds light on this phenomenon by combining newer, shallower sediment analyses with deeper cores that provide a look at conditions spanning the past 8,000 years.
These layered sediments reveal two critical junctures where human influence became apparent in the lake's lifecycle. The first instance occurred with the establishment of Mormon settlements in 1847, which introduced significant agricultural activity to the area. Bowen told At The U, "We see a big shift in the carbon isotopes, and it shifts from values that are more indicative of rock weathering, carbon coming into the lake from dissolving limestone, toward more organic sources, more vegetation sources." This change signals a profound deviation in the lake's carbon composition.
Another significant alteration came in 1959, when the construction of a railroad causeway bifurcated the Great Salt Lake, severely impacting its salinity and water levels. The south arm, also known as Gilbert Bay, was affected most acutely, becoming partially drained into Gunnison Bay, an alteration not seen in thousands of years. "We changed the hydrology of the lake fundamentally and gave it an outflow. We see that really clearly in the oxygen isotopes, which start behaving in a different way," Bowen explained, as obtained by At The U.
