Friday, August 22, 2014
PLACERVILLE, CALIFORNIA
99 CENTS

Rock doc: Mercury contamination from the good old days

By
December 14, 2013 |

When I was a younger and more sprightly woman, I spent part of my life investigating unusual hot springs in rural California. They were salty and quite stinky springs out in the middle of nowhere, and several of them occurred right in the center of an old gold-laced mercury deposit.
No one was actively mining the small area where the springs are found. There just wasn’t enough ore to make the project economic. But the rocks of the location had small veins of chalcedony, calcite and other minerals that had elevated values of both gold and mercury in them. Working with a couple of colleagues, I took samples of the spring waters, the gases bubbling out of the springs, the precipitates forming around them, and anything that looked interesting in the nearby rocks.
The fieldwork had its challenges. In the afternoon it was routinely over 100 degrees, and the sun was relentless. One afternoon I even flirted with heat stroke. Another problem was that the rattlesnakes were numerous and big.
I spent a lot of time in the laboratory back East analyzing the waters of the springs. They were transporting gold, and the question was how. Gold is normally quite insoluble. That’s why it can be used to crown a tooth. Even in an environment rich in warm spit and sips of hot coffee, a golden tooth won’t dissolve away because gold is quite insoluble under most conditions. But clearly the hot springs were different. In the end, I concluded that sulfur in the spring waters was keeping the gold in solution until the waters broke to the surface and the gold precipitated out as temperature and gas concentrations changed.
There were some other interesting things about the strange springs, too. Some of the cooler ones had the larval stage of an insect living in them. I took samples of the wiggling little creatures and gave them to a biologist to identify. The insect normally lives around the ocean in salt-marshes, but it was making use of the salty springs even though they were well inland.
The area where I worked in California hadn’t played a direct role in the Gold Rush of 1849. There just wasn’t enough gold around the hot springs to have caught the attention of the old timers who made fortunes elsewhere in California. But the place where I worked had been mined for mercury, including back in the old days. That was because mercury was used to concentrate gold in materials miners elsewhere were processing.
In the old days, miners worked with pans, hydraulic hoses, and sluices to remove and concentrate gold-rich sediment. Because gold is attracted to mercury, the miners poured liquid mercury on the earthen material they had concentrated. The gold moved into the mercury. The miners could then heat the mercury and boil it away, leaving a concentrated “button” of gold behind.
There was a lot of mercury being slopped around in the old processes the miners used. Much of it went into the air when the miners heated the mercury-gold mixture, but some of the mercury stayed behind, in the sediments.
New research is highlighting the environmental challenges those old mining techniques continue to create for us today. As explained in a recent piece on the Website Inside Science, one of the key places at issue is the Yuba Fan, a volume of sediment built up around the Yuba River, a tributary of the Sacramento River.
“The Yuba Fan is totally artificial, created by humans,” Michael Singer of the University of St. Andrews said to Inside Science.
The Yuba Fan contains more than a billion cubic yards of sediment. Terraces in the fan act like small dams, keeping the material from moving downstream. But about once every 10 years there is a substantial flood that kicks loose materials that then move downhill toward the lowlands — which include agricultural areas like California’s rice fields.
The recent research was published in the Proceedings of the National Academy of Sciences, which is a measure of its importance. In part because California’s agricultural bounty is a keystone to all of us who like to eat, I’m sure more follow-up research will be done.
Dr. E. Kirsten Peters, a native of the rural Northwest, was trained as a geologist at Princeton and Harvard. This column is a service of the College of Agricultural, Human and Natural Resource Sciences at Washington State University.

Comments

Subscription Required

Thank you for reading the MtDemocrat.com digital edition. In order to continue reading this story please choose one of the following options.

Current Subscribers
If you are a current subscriber and wish to obtain access to MtDemocrat.com, please select the Subscriber Verification option below. If you already have a login, please select "Login" at the lower right corner of this box.

Subscriber Verification

Special Introductory Offer
For a short time we will be offering a discount to those who call us in order to obtain access to MtDemocrat.com and start your print subscription. Our customer support team will be standing by Monday through Friday, 8am to 5pm to assist you.

Call and Save! (530) 344-5000

If you are not a current subscriber and wish not to take advantage of our special introductory offer, please select the $12 monthly option below to obtain access to MtDemocrat.com and start your online subscription

Help?

E. Kirsten Peters

.

News

 
County Counsel retires next week

By Chris Daley | From Page: A1 | Gallery

Patrol car hit in collision

By Cole Mayer | From Page: A1

 
‘When I’m 64…’: Pebble Beach Concours shows it’s got muscle

By Larry Weitzman | From Page: B1 | Gallery

Murder-suicide? Elderly couple found dead

By Cole Mayer | From Page: A1

 
Heard over the back fence: Sand Fire Benefit Aug. 22

By Bob Billingsley | From Page: B1

Sand Fire benefit tonight

By Dawn Hodson | From Page: A1

 
County unemployment up to 7.2 percent

By Michael Raffety | From Page: A3

Eldorado National Forest chosen for new wildland fire project

By Usda Forest Service | From Page: A3

 
Burke’s Corner: August 22, 2014

By Special to the Democrat | From Page: A8

NRA grants awarded, application process begins

By News Release | From Page: A8

 
Child Support Awareness Month

By News Release | From Page: A10

Fundraiser to benefit Animal Outreach

By News Release | From Page: A10

 
Water Agency gets preview of water rights project

By Dawn Hodson | From Page: A11

.

Opinion

Something to think about: Star Trek and Dog Days

By Wendy Schultz | From Page: A4

 
Mystery savings

By Mountain Democrat | From Page: A4

 
.

Letters

Frentzen for Supervisor District 2

By Letters to the Editor | From Page: A2

 
Amaral for Supervisor (District 2)

By Letters to the Editor | From Page: A5

Consequences of initiatives

By Letters to the Editor | From Page: A5

 
Vote for Todd White

By Letters to the Editor | From Page: A5

Another Logan Building Grand Jury report

By Letters to the Editor | From Page: A5

 
Head Start hours cut

By Letters to the Editor | From Page: A5

Mather approval hearing article

By Letters to the Editor | From Page: A5

 
.

Sports

College boxing route for local pair

By Jerry Heinzer | From Page: A6 | Gallery

 
Fox to enter section’s Hall of Fame

By Democrat Staff | From Page: A6

 
‘When The Game Stands Tall’

By Mike Bush | From Page: A6 | Gallery

Take the challenge at Crazy Eights Trail races

Press Release | From Page: A7

 
.

Prospecting

Things to do 8-22-14

By Michael Raffety | From Page: B2

 
‘All My Sons’: Sierra Rep stages Arthur Miller play

By Sierra Repertory | From Page: B2

EDCOE Pearson Vue Testing Center grand opening

By El Dorado County Office of Education | From Page: B2

 
FLC theater to audition for ‘Anon(ymous)’

By Folsom Lake College | From Page: B2

Low-cost flu clinics announced

By Health and Human Services Agency | From Page: B4

 
Cast adrift in the Pacific: Life as I know it: Robert F. Boggus

By Robert F. Boggus | From Page: B4 | Gallery

Remembering EDH columnist Millie Smith

By Special to the Democrat | From Page: B5

 
Twisted Oak event

By Twisted Oak | From Page: B5

Concorso Italiano — Italy in Monterey

By Special to features | From Page: B6 | Gallery

 
.

Essentials

.

Obituaries

Barbara Ellen Pratt

By Mountain Democrat | From Page: A2

 
Marilyn K. Brown death notice

By Contributor | From Page: A2

Ruby M. (Elvers) Buck funeral notice

By Contributor | From Page: A2

 
Dennis Jack Fike

By Contributor | From Page: A2

Cecil W. Jones

By Contributor | From Page: A2

 
.

Real Estate

Day of reckoning approaches for HELOC borrowers

By Ken Calhoon | From Page: HS3

 
Putting the grace in gracious living

By Marni Jameson | From Page: HS4

Home-price gains decelerate in many metro areas

Press Release | From Page: HS6

 
Luxurious Marion fits on narrow corner lot

Press Release | From Page: HS7

Traditional, modern meld in Pinedale

Press Release | From Page: HS14

 
.

Comics

Print edition, Friday, August 22, 2014

By Contributor | From Page: A1

 
TV Listings

By Contributor | From Page: A9

Speed Bump

By Contributor | From Page: A9

 
Tundra

By Contributor | From Page: A9

Shoe

By Contributor | From Page: A9

 
Sudoku

By Contributor | From Page: A9

Rubes

By Contributor | From Page: A9

 
Long Story Short

By Contributor | From Page: A9

New York Times Crossword

By Contributor | From Page: A10

 
Horoscope, Sunday, August 24, 2014

By Contributor | From Page: A10

Horoscope, Saturday, August 23, 2014

By Contributor | From Page: A10

 
Horoscope, Friday, August 22, 2014

By Contributor | From Page: A10

.

Home Source

Day of reckoning approaches for HELOC borrowers

By Ken Calhoon | From Page: HS3

Putting the grace in gracious living

By Marni Jameson | From Page: HS4

Home-price gains decelerate in many metro areas

Press Release | From Page: HS6

Luxurious Marion fits on narrow corner lot

Press Release | From Page: HS7

Traditional, modern meld in Pinedale

Press Release | From Page: HS14