Document Type
Article
Publication Date
November 2018
Publication Title
Elementa: Science of the Anthropocene
Volume
6
DOI
10.1525/elementa.333
Abstract
Since the onset of hydraulic gold mining in California’s Sierra Nevada foothills in 1852, the environmental damage caused by displacement and storage of hydraulic mining sediment (HMS) has been a significant ecological problem downstream. Large volumes of mercury-laden HMS from the Yuba River watershed were deposited within the river corridor, creating the anthropogenic Yuba Fan. However, there are outstanding uncertainties about how much HMS is still contained within this fan. To quantify the deep storage of HMS in the Yuba Fan, we analyzed mercury concentrations of sediment samples collected from borings and outcrops at multiple depths. The mercury concentrations served as chemostratigraphic markers to identify the contacts between the HMS and underlying pre-mining deposits. The HMS had mercury concentrations at least ten-fold higher than pre-mining deposits. Analysis of the lower Yuba Fan’s volume suggests that approximately 8.1 . 107 m3 of HMS was deposited within the study area between 1852 and 1999, representing ~32% of the original Yuba Fan delivered by 19th Century hydraulic gold mining. Our estimate of the mercury mass contained within this region is 6.7 . 103 kg, which is several orders of magnitude smaller than what was estimated to have been lost to the mining process. We suggest that this discrepancy is likely due to a combination of missing (yet to be found) mercury masses stored upstream, overestimated losses during mining, and high delivery of mercury to the lowland Sacramento Valley and to the San Francisco Bay-Delta system, where it poses a great risk to sensitive ecosystems.
Recommended Citation
Tyler Nakamura, Michael Bliss Singer, and Emmanuel Gabet. "Remains of the 19th Century: Deep storage of contaminated hydraulic mining sediment along the Lower Yuba River, California" Elementa: Science of the Anthropocene (2018). https://doi.org/10.1525/elementa.333
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Comments
This article was published by the University of California Press and appeared in Elementa: Science of the Anthropocene, volume 6, 2018.
© 2018 The Author(s). This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International License (CC-BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. See http://creativecommons.org/licenses/by/4.0/.