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@article{Portenga:2019:10.1130/B31840.1,
author = {Portenga, EW and Bierman, PR and Trodick, CD and Greene, SE and DeJong, BD and Rood, DH and Pavich, MJ},
doi = {10.1130/B31840.1},
journal = {Geological Society of America Bulletin},
pages = {1295--1311},
title = {Erosion rates and sediment flux within the Potomac River basin quantified over millennial timescales using beryllium isotopes},
url = {http://dx.doi.org/10.1130/B31840.1},
volume = {131},
year = {2019}
}

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TY  - JOUR
AB  - Beryllium isotopes measured in detrital river sediment are often used to estimate rates of landscape change at a basin scale, but results from different beryllium isotope systems have rarely been compared. Here, we report measurements of in situ and meteoric 10Be (10Bei and 10Bem, respectively) along with measurements of reactive and mineral phases of 9Be (9Bereac and 9Bemin, respectively) to infer long-term rates of landscape change in the Potomac River basin, North America. Using these data, we directly compare results from the two different 10Be isotope systems and contextualize modern sediment flux from the Potomac River basin to Chesapeake Bay.Sixty-two measurements of 10Bei in river sand show that the Potomac River basin is eroding on average at 29.6 ± 14.1 Mg km–2 yr–1 (11 ± 5.2 m m.y.–1 assuming a rock density of 2700 kg m–3)—a rate consistent with other estimates in the mid-Atlantic region. 10Bei erosion rates correlate with basin latitude, suggesting that periglacial weathering increased with proximity to the former Laurentide Ice Sheet margin. Considering the 10Bei-derived erosion rate as a sediment flux over millennia, rates of sediment delivery from the Potomac River to Chesapeake Bay are up to ∼5× lower than contemporary sediment yields implying modern land-use practices have accelerated erosion and sediment transport over background rates. However, 10Bei erosion rate data suggest that regulatory benchmark levels used to manage sediment export from the Potomac River basin to Chesapeake Bay are set appropriately to reduce sedimentation and restore the Bay’s ecological health.The mean of 56 10Bem/9Bereac-derived denudation rates (40.0 ± 21.7 Mg km–2 yr–1) is higher than, but statistically indistinguishable from, the mean 10Bei erosion rate (29.6 ± 14.1 Mg km–2 yr–1; p = 0.003). However, when considered basin by basin, 10Bem/9Bereac-determined denudation rate
AU  - Portenga,EW
AU  - Bierman,PR
AU  - Trodick,CD
AU  - Greene,SE
AU  - DeJong,BD
AU  - Rood,DH
AU  - Pavich,MJ
DO  - 10.1130/B31840.1
EP  - 1311
PY  - 2019///
SN  - 0016-7606
SP  - 1295
TI  - Erosion rates and sediment flux within the Potomac River basin quantified over millennial timescales using beryllium isotopes
T2  - Geological Society of America Bulletin
UR  - http://dx.doi.org/10.1130/B31840.1
UR  - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000471802800013&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
UR  - https://pubs.geoscienceworld.org/gsa/gsabulletin/article/131/7-8/1295/568785/Erosion-rates-and-sediment-flux-within-the-Potomac
UR  - http://hdl.handle.net/10044/1/72517
VL  - 131
ER  -

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