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Images: Elemental Journeys

Enormous amounts of chemical elements move throughout the surface of the Earth. This illustrates  how much is moved by various natural processes or human activities, in units of petagrams (Pg = 1015 grams), teragrams (Tg = 1012), and gigagrams (Gg =109). Human activities include farming, mining, and construction. Natural processes include eroded material carried by the winds or transported by rivers, and chemical compounds mobilized by the growth and decay of living things, or net primary production (NPP). HANPP (human apportionment of net primary production) is a measure of the degree to which human activities, such as farming, have influenced net primary production. (Reprinted with permission from <em>Environmental Science & Technology</em> © 2012, American Chemical Society)

A new study by Woods Hole Oceanographic Institution scientists concluded that human activities have substantially altered natural processes that cycle elements through soils, rocks, water, and atmosphere. Yellow triangles show the percentage of human impact on element cycles if soil erosion is treated as an entirely natural process. Red symbols show the percentage of human impact on element cycles if soil erosion is treated as partially (in this case 50%) caused by human activities. (Reprinted with permission from Environmental Science & Technology © 2012, American Chemical Society)

Indra Sen, a postdoctoral scientist at WHOI, was lead author of the study published in Environmental Science & Technology. (Courtesy of Indra Sen)

WHOI geochemist Bernhard Peucker-Ehrenbrink was co-author of the study. (Jayne Doucette, Woods Hole Oceanographic Institution)