Posted By jngraves on 25 Jan 2015 – 11:50pm in Biological Sciences, Ecology, Physical Sciences, Climate Change, Geology | 0 comments
It is a well known fact that deforestation and agriculture increases erosion above its natural rate. However, accurately measuring the natural rate of erosion and how much human land use has accelerated this rate, becomes an increasingly arduous task for geologists. Inevitably this makes environmental decisions like setting allowable amounts of sediment in fish habitats, extremely problematic.
New research on the Roanoke, Savannah, and Chattahoochee Rivers along with seven other large river basins in the US Southeast, has for the first time, precisely determined this mixed rate of erosion. The new study is going to be presented in the February issue of the journal Geology, and is supported by the National Science Foundation. From this new research, scientists have now made a startling discovery that the rates of hill-slope erosion before European settlement were about an inch every 2500 years, while during the period of peak land disturbance in the late 1800’s and early 1900’s, rates spiked to an inch every 25 years.
To find their results, scientists collected twenty-four sediment samples from the rivers, and then applied an innovative technique to take the data measurements. The team took quartz samples from the sediment and extracted a rare form of the element beryllium; an isotope called beryllium-10. Developed by cosmic rays, this rare isotope builds up over time in the top few feet of soil deposits. If the rate of erosion is slow in a sample, and the soil was exposed at the Earth’s surface for a long period of time, the data will show a higher concentrations of beryllium-10 than if the soil had eroded at a quicker rate.
While this new study shows that erosion rates were unsustainable in the recent past, “…it also provides a goal for the future,” Rood says. “We can use the beryllium-10 erosion rates as a target for successful resource conservation strategies; they can be used to develop smart environmental policies and regulations that will protect threatened soil and water resources for generations to come.”
Biological Sciences, Ecology, Physical Sciences, Climate Change, Geology
Geology, Erosion, Soil