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Title: Intraday Water Quality Patterns in East Fork Poplar Creek with an Emphasis on Mercury and Monomethylmercury

Abstract

We conducted a diel sampling campaign at three locations along the Hg contaminated East Fork Poplar Creek (EFPC) in Oak Ridge, Tennessee to (i) quantify diel patterns of particulate and dissolved mercury (Hg) and monomethylmercury (MMHg) (HgD, HgP, MMHgD, and MMHgP, respectively) and associated water quality parameters along a longitudinal gradient of EFPC during the summer season, (ii) determine if diel patterns in Hg and/or MMHg are related to the daily photocycle or any other short term cycle, such as wastewater treatment plant discharge, (iii) determine if diel variability in turbidity and dissolved organic matter (DOM) composition correspond to particulate HgP or MMHgP and dissolved organic carbon (DOC) or dissolved HgD or MMHgD. Samples were collected every two hours for a 30 hour period. The farthest upstream site was located at the boundary of Y-12 and the City of Oak Ridge (EFK 23.4) while two additional sites were located 7.2 kilometers (Wiltshire Drive, EFK 16.2) and 18 kilometers (Horizon Center, EFK 5.4) downstream of EFK 23.4).HgP and MMHgP concentrations increased overnight at EFK 16.2 and EFK 5.4 coincident with increases in turbidity and total suspended solids (TSS). These overnight increases were likely due to diel changes in the activity ofmore » macrobiota (re)suspending contaminated sediments in the creek. Both HgD and MMHgD were higher during the day at EFK 23.4 and EFK 5.4. The underlying causes for the patterns in HgD and MMHgD are less clear but correspond with similar patterns in DOC concentration and DOM composition. Photochemical reactions may also play a role in these HgD, MMHgD, DOC, and DOM patterns. Both Hg and MMHg loading increased with downstream distance. The greatest increase in loading occurred in the reach from EFK 23.4 to EFK 16.2 which encompasses areas where the Historic Release Deposits (HRD) have been identified. These results suggest that diffuse legacy sources of Hg, outside of Y-12, contribute Hg load to EFPC whereas MMHg is generated from instream processes.Intraday patterns in Hg and MMHg concentration and speciation have implications with respect to biotic exposure. Greater biotic activity and feeding during times of higher concentration would correspond to greater exposure than estimated from daily or longer term averages. Both Hg and MMHg responded rapidly to processes governing their concentration. This latter point is encouraging from the perspective of site remediation as it suggests that MMHg concentrations and flux in EFPC would respond rapidly to appropriate remedial actions.« less

Authors:
 [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Environmental Management (EM)
OSTI Identifier:
1439147
Report Number(s):
ORNL/TM-2018/812
DOE Contract Number:
AC05-00OR22725
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English

Citation Formats

Brooks, Scott C., and Lowe, Kenneth Alan. Intraday Water Quality Patterns in East Fork Poplar Creek with an Emphasis on Mercury and Monomethylmercury. United States: N. p., 2018. Web. doi:10.2172/1439147.
Brooks, Scott C., & Lowe, Kenneth Alan. Intraday Water Quality Patterns in East Fork Poplar Creek with an Emphasis on Mercury and Monomethylmercury. United States. doi:10.2172/1439147.
Brooks, Scott C., and Lowe, Kenneth Alan. Tue . "Intraday Water Quality Patterns in East Fork Poplar Creek with an Emphasis on Mercury and Monomethylmercury". United States. doi:10.2172/1439147. https://www.osti.gov/servlets/purl/1439147.
@article{osti_1439147,
title = {Intraday Water Quality Patterns in East Fork Poplar Creek with an Emphasis on Mercury and Monomethylmercury},
author = {Brooks, Scott C. and Lowe, Kenneth Alan},
abstractNote = {We conducted a diel sampling campaign at three locations along the Hg contaminated East Fork Poplar Creek (EFPC) in Oak Ridge, Tennessee to (i) quantify diel patterns of particulate and dissolved mercury (Hg) and monomethylmercury (MMHg) (HgD, HgP, MMHgD, and MMHgP, respectively) and associated water quality parameters along a longitudinal gradient of EFPC during the summer season, (ii) determine if diel patterns in Hg and/or MMHg are related to the daily photocycle or any other short term cycle, such as wastewater treatment plant discharge, (iii) determine if diel variability in turbidity and dissolved organic matter (DOM) composition correspond to particulate HgP or MMHgP and dissolved organic carbon (DOC) or dissolved HgD or MMHgD. Samples were collected every two hours for a 30 hour period. The farthest upstream site was located at the boundary of Y-12 and the City of Oak Ridge (EFK 23.4) while two additional sites were located 7.2 kilometers (Wiltshire Drive, EFK 16.2) and 18 kilometers (Horizon Center, EFK 5.4) downstream of EFK 23.4).HgP and MMHgP concentrations increased overnight at EFK 16.2 and EFK 5.4 coincident with increases in turbidity and total suspended solids (TSS). These overnight increases were likely due to diel changes in the activity of macrobiota (re)suspending contaminated sediments in the creek. Both HgD and MMHgD were higher during the day at EFK 23.4 and EFK 5.4. The underlying causes for the patterns in HgD and MMHgD are less clear but correspond with similar patterns in DOC concentration and DOM composition. Photochemical reactions may also play a role in these HgD, MMHgD, DOC, and DOM patterns. Both Hg and MMHg loading increased with downstream distance. The greatest increase in loading occurred in the reach from EFK 23.4 to EFK 16.2 which encompasses areas where the Historic Release Deposits (HRD) have been identified. These results suggest that diffuse legacy sources of Hg, outside of Y-12, contribute Hg load to EFPC whereas MMHg is generated from instream processes.Intraday patterns in Hg and MMHg concentration and speciation have implications with respect to biotic exposure. Greater biotic activity and feeding during times of higher concentration would correspond to greater exposure than estimated from daily or longer term averages. Both Hg and MMHg responded rapidly to processes governing their concentration. This latter point is encouraging from the perspective of site remediation as it suggests that MMHg concentrations and flux in EFPC would respond rapidly to appropriate remedial actions.},
doi = {10.2172/1439147},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2018},
month = {Tue May 01 00:00:00 EDT 2018}
}

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