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Methylmercury production in and export from agricultural wetlands in California, USA: The need to account for physical transport processes into and out of the root zone

Overview of attention for article published in Science of the Total Environment, February 2014
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Title
Methylmercury production in and export from agricultural wetlands in California, USA: The need to account for physical transport processes into and out of the root zone
Published in
Science of the Total Environment, February 2014
DOI 10.1016/j.scitotenv.2013.11.086
Pubmed ID
Authors

P.A.M. Bachand, S.M. Bachand, J.A. Fleck, C.N. Alpers, M. Stephenson, L. Windham-Myers

Abstract

Concentration and mass balance analyses were used to quantify methylmercury (MeHg) loads from conventional (white) rice, wild rice, and fallowed fields in northern California's Yolo Bypass. These analyses were standardized against chloride to distinguish transport pathways and net ecosystem production (NEP). During summer, chloride loads were both exported with surface water and moved into the root zone at a 2:1 ratio. MeHg and dissolved organic carbon (DOC) behaved similarly with surface water and root zone exports at ~3:1 ratio. These trends reversed in winter with DOC, MeHg, and chloride moving from the root zone to surface waters at rates opposite and exceeding summertime root zone fluxes. These trends suggest that summer transpiration advectively moves constituents from surface water into the root zone, and winter diffusion, driven by concentration gradients, subsequently releases those constituents into surface waters. The results challenge a number of paradigms regarding MeHg. Specifically, biogeochemical conditions favoring microbial MeHg production do not necessarily translate to synchronous surface water exports; MeHg may be preserved in the soils allowing for release at a later time; and plants play a role in both biogeochemistry and transport. Our calculations show that NEP of MeHg occurred during both summer irrigation and winter flooding. Wild rice wet harvesting and winter flooding of white rice fields were specific practices that increased MeHg export, both presumably related to increased labile organic carbon and disturbance. Outflow management during these times could reduce MeHg exports. Standardizing MeHg outflow:inflow concentration ratios against natural tracers (e.g. chloride, EC) provides a simple tool to identify NEP periods. Summer MeHg exports averaged 0.2 to 1 μg m(-2) for the different agricultural wetland fields, depending upon flood duration. Average winter MeHg exports were estimated at 0.3 μg m(-2). These exports are within the range reported for other shallow aquatic systems.

Twitter Demographics

The data shown below were collected from the profile of 1 tweeter who shared this research output. Click here to find out more about how the information was compiled.

Mendeley readers

The data shown below were compiled from readership statistics for 29 Mendeley readers of this research output. Click here to see the associated Mendeley record.

Geographical breakdown

Country Count As %
Canada 1 3%
Unknown 28 97%

Demographic breakdown

Readers by professional status Count As %
Researcher 7 24%
Student > Ph. D. Student 5 17%
Student > Master 2 7%
Other 2 7%
Professor 2 7%
Other 4 14%
Unknown 7 24%
Readers by discipline Count As %
Agricultural and Biological Sciences 7 24%
Environmental Science 7 24%
Social Sciences 2 7%
Economics, Econometrics and Finance 2 7%
Arts and Humanities 1 3%
Other 2 7%
Unknown 8 28%

Attention Score in Context

This research output has an Altmetric Attention Score of 1. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 05 January 2014.
All research outputs
#12,362,052
of 15,557,520 outputs
Outputs from Science of the Total Environment
#10,855
of 14,355 outputs
Outputs of similar age
#185,621
of 265,767 outputs
Outputs of similar age from Science of the Total Environment
#120
of 181 outputs
Altmetric has tracked 15,557,520 research outputs across all sources so far. This one is in the 11th percentile – i.e., 11% of other outputs scored the same or lower than it.
So far Altmetric has tracked 14,355 research outputs from this source. They typically receive a little more attention than average, with a mean Attention Score of 7.2. This one is in the 13th percentile – i.e., 13% of its peers scored the same or lower than it.
Older research outputs will score higher simply because they've had more time to accumulate mentions. To account for age we can compare this Altmetric Attention Score to the 265,767 tracked outputs that were published within six weeks on either side of this one in any source. This one is in the 16th percentile – i.e., 16% of its contemporaries scored the same or lower than it.
We're also able to compare this research output to 181 others from the same source and published within six weeks on either side of this one. This one is in the 17th percentile – i.e., 17% of its contemporaries scored the same or lower than it.