By Sid Perkins
Sediments in lakes and bogs along the eastern coast of the United States show that midlatitude bodies of water have sequestered higher amounts of carbon than those at other latitudes have since the last ice age.
Byrdie Renik, an earth scientist at Columbia University, analyzed data compiled about the organic content of sediments deposited in more than 50 lakes and bogs throughout the eastern United States during the past 10,000 years. There is a considerable range of average temperatures across the region but only a small variation in annual precipitation.
Although warmer temperatures fueled higher growth rates of vegetation in lakes and bogs at lower latitudes, they also accelerated the rate of decomposition. Conversely, vegetation at higher latitudes grew more slowly but didn’t decompose as quickly, Renik notes.
The highest amounts of organic matter were in sediments taken from bodies of water between the latitudes of 40N and 43N, in the mid-Atlantic and New England regions. At these middle latitudes, the sediments seem to record both high rates of vegetative growth and low rates of organic decomposition.
