Christopher C. Fuller Peter C. Van Metre Allen C. Gellis 2017 <p><span>Fallout radionuclides,&nbsp;</span>⁷<span>Be and<span>&nbsp;</span></span>²¹⁰<span>Pb</span>_ex<span>, sampled in bed sediment for 99 watersheds in the Midwestern region of the United States and in 15 samples of suspended sediment from 3 of these watersheds were used to partition upland from channel sources and to estimate the age or the time since the surface-derived portion of sediment was on the land surface (0–∼1 year). Channel sources dominate: 78 of the 99 bed material sites (79%) have &gt;50% channel-derived sediment, and 9 of the 15 suspended-sediment samples (60%) have &gt;50% channel-derived sediment.<span>&nbsp;</span></span>⁷<span>Be was detected in 82 bed sediment samples and all 15 suspended-sediment samples. The surface-derived portion of 54 of the 80 (68%) streams with detectable<span>&nbsp;</span></span>⁷<span>Be and<span>&nbsp;</span></span>²¹⁰<span>Pb</span>_ex<span><span>&nbsp;</span>were&nbsp;≤&nbsp;100 days old and the surface-derived portion of all suspended-sediment samples were&nbsp;≤&nbsp;100 days old, indicating that surface-derived fine-grained sediment moves rapidly though these systems. The concentrations of two hydrophobic pesticides–DDE and bifenthrin–are correlated with the proportion of surface-derived sediment, indicating a link between geomorphic processes and particle-associated contaminants in streams. Urban areas had the highest pesticide concentrations and the largest percentage of surface-derived sediment. Although the percentage of surface-derived sediment is less than channel sources at most of the study sites, the relatively young age of the surface-derived sediment might indicate that management actions to reduce sediment contamination where the land surface is an important source could have noticeable effects.</span></p> application/pdf 10.1016/j.jenvman.2016.06.018 en Elsevier Sources and ages of fine-grained sediment to streams using fallout radionuclides in the Midwestern United States article