New Merury Study 2011

[jerhobbs]

This is not good for the suction dredge community

Prepared in cooperation with the Bureau of Land Management and the California State Water Resources Control Board
The Effects of Sediment and Mercury Mobilization in the South Yuba River and Humbug Creek Confluence Area, Nevada County, California: Concentrations, Speciation, and Environmental Fate–Part 1: Field Characterization
Jacob A. Fleck, Charles N. Alpers, Mark Marvin-DiPasquale, Roger L. Hothem, Scott A. Wright, Kevin Ellett, Elizabeth Beaulieu, Jennifer L. Agee, Evangelos Kakouros, Le H. Kieu, Dennis D. Eberl, Alex E. Blum, and Jason T. May

FPRIVATE "TYPE=PICT;ALT=Thumbnail of and link to report PDF (16.5 MB)" ABSTRACT
Millions of pounds of mercury (Hg) were deposited in the river and stream channels of the Sierra Nevada from placer and hard-rock mining operations in the late 1800s and early 1900s. The resulting contaminated sediments are relatively harmless when buried and isolated from the overlying aquatic environment. The entrained Hg in the sediment constitutes a potential risk to human and ecosystem health should it be reintroduced to the actively cycling portion of the aquatic system, where it can become methylated and subsequently bioaccumulated in the food web. Each year, sediment is mobilized within these fluvial systems during high stormflows, transporting hundreds of tons of Hg-laden sediment downstream. The State of California and resource-management agencies, including the Bureau of Land Management (BLM) and the U.S. Forest Service, are concerned about additional disturbances, such as from suction gold dredging activities, which have the potential to mobilize Hg associated with buried sediment layers elevated in Hg that are otherwise likely to remain buried under normal storm conditions.
The BLM initiated a study looking at the feasibility of removing Hg-contaminated sediment at the confluence of the South Yuba River and Humbug Creek in the northern Sierra Nevada of California by using standard suction-dredge technology. Additionally, the California State Water Resources Control Board (SWRCB) supported a comprehensive characterization of the intended dredge site. Together, the BLM and SWRCB supported a comprehensive characterization of Hg contamination at the site and the potential effects of sediment disturbance at locations with historical hydraulic mining debris on downstream environments. The comprehensive study consisted of two primary components: field studies and laboratory experiments. The field component, described in this report, had several study elements: 1) a preliminary, smallscale, in-stream dredge test; 2) comprehensive characterization of grain size distribution, Hg speciation, and mineralogy of bed and suspended sediment; 3) a determination of the past and current sources of sediment in the study area; 4) an assessment of Hg bioaccumulation in the local invertebrate population; and 5) a comparison of potential Hg transport caused by natural storm disturbances with potential Hg mobilization caused by suction dredging as a method of Hg removal at the study site. The laboratory component of the study assessed the potential influence of the disturbance of Hg-contaminated sediment through experiments designed to simulate in-stream transport, deposition, and potential methylation of Hg, described in a companion report (see Marvin-DiPasquale and others, 2011).
Results of the field studies indicate that the fine-grained fraction (silt-clay, less than 0.063 millimeters) contains the greatest concentration of Hg in contaminated sediment. Because the fine-grained fraction is the most susceptible to longrange fluvial transport, disturbance of Hg-contaminated sediment is likely to increase the concentration and load of Hg in downstream waters. The preliminary, small-scale dredge test showed an increase in the concentration of fine particles and Hg in the water column caused by the dredge activity, despite relatively low concentrations of fine particles and Hg (about 300 nanograms per gram) at the dredge site. Characterization of sediment from two test pits and other sites in the vicinity of the confluence of the South Yuba River and Humbug Creek revealed a highly variable distribution of fine- and coarse-grained sediment. The highest levels of Hg contamination (up to 11,100 ng/g) were associated with the fine-grained fraction of sediment from the bedrock contact zone of Pit 2, a horizon which also yielded grains of gold and gold-Hg amalgam.
A closed-circuit tank experiment with a venturi dredge at the base of Pit 1, in a gravel bar within the South Yuba River, resulted in fine-grained suspended sediment remaining in suspension more than 40 hours following the disturbance simulation. Although the volumetric concentration of Hg declined over time as particles settled out, the concentration of Hg on the suspended particles increased over time as the suspended material became finer grained, because Hg is preferentially adsorbed on to clay-sized particles. Mineralogical and chemical analyses indicated that the buried fine-grained material with the greatest Hg contamination was derived from hydraulic mining debris, which consist primarily of Eocene gravels mined in the Malakoff Diggins, North Bloomfield, and Lake City areas within the South Yuba River watershed. Coarse material and more recently deposited sediment were derived primarily from upstream sources on the South Yuba River.
The biota assessment indicated that invertebrate taxa collected from all sites on the South Yuba River in 2007, including lower Humbug Creek, had elevated concentrations of total mercury (THg) and methylmercury (MeHg) compared to a reference site on the Bear River, upstream of mining effects. Differences with the reference site were less pronounced in 2008 when a significant reduction in MeHg concentrations was observed in biota across all taxa from concentrations in 2007. It is possible that the inter-annual variation was related to the fact that suction dredging was active in the South Yuba River in 2007 but not in 2008 when a local moratorium was imposed by the BLM. There were significant variations among taxa for both THg and MeHg concentrations, with the water striders (Gerridae) having the highest concentrations of both THg and MeHg; variation among sites was not as strong as between years or among taxa. These results suggest that additional monitoring would be helpful to investigate the possible linkage between variations in MeHg bioaccumulation and levels of suction dredge activity in areas of historical gold mining.
Results from the field studies indicate that disturbance of the finegrained Hg-contaminated sediment would likely lead to enhanced mobilization of Hg to downstream environments; therefore, the use of suction dredging to remove Hg at the South Yuba River and Humbug Creek confluence area would likely result in enhanced Hg transport downstream relative to natural conditions. First posted January 25, 2011
Report PDF (16.5 MB)
For additional information contact:
Director, California Water Science Center
U.S. Geological Survey
6000 J Street, Placer Hall
Sacramento, California 95819
http://ca.water.usgs.gov
Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.

[CalGoldDredger]

No for me as I knew that was coming.

All comes to light now.
Untimely Delay of CDFG SEIR 12/14/2010,
EPA Klamath Restoration Plan 1/4/2011,
and Mercury Study 1/25/2011.

Direct Quote from e-mail from M. Stopher at CDFG on 1/11/2011:
"THE EPA approval of the Total maximum Daily Load plan for the Klamath River has nothing to do with our suction dredge regulation schedule. I've also heard assertions that a USGS report on mercury delayed our schedule. it did not."
Total BS, Lies.

What does this all mean...we soon shall find out as February is a week away unless Stopher keeps us in a continuous delay.

Where is that there Craven Raven, what does he sayeth???

I am so glad I am going North, to Alaska to dredge. Get out why the gettin's still good.

[dickb]

Hi CGD:

One thing that your should check into when your up there is to try and establish permanent residency. You might benefit from doing it and if your up long enough to get established, say by owning some property, you can leave your equipment up there during the winter and won't have the long drive both ways. You still can come back to cali for the winter and work your claims down there. Might even be some tax advantage for you to do it.

A lot of the locals up there come south for the winter to stay warm.

Dickb

[Hoser John]

I BEEN FRIGGN' TELLING YA'ALL FOR YEARS AND TALKED TO THE SCIENTIST PHONEYING UP THIS PRECONCEIVED RULING BS-DEAD IN ALL STATES AS FEDERAL LAWS EMBELISH THIS INSANITY WITH RULE FROM SEA TO SHING SEA-f''m'-going dredging with my new dredge. That mo fo Stopher wouldn't know the truth ifn' it crawled up and bite him in his testicles---John

[CalGoldDredger]

Here is a PDF web link of the full report/study, BS. If anyone cares to read the lies and bull crap. http://pubs.usgs.gov/of/2010/1325A/pdf/ofr20101325a.pdf

State Water Board + EPA + USGS + CDFG + Indian Casino $$$ Backer = A Whole Lot Of Real Smelly & The Very End Of Dredging For Us All.

Special Thanks for those miners helping miners, the new 86ers which made it all possible. F'M'

[Bonaro]

I noticed that a study of HG suspension in the water during normal winter high water was not performed. I would bet that mother nature stirs up far more than dredgers do.
The report opens witht he claim that "millions of pounds" of mercury was deposited in the river....exactly how would they get that number????

[russau]

they got that number by pulling it out of the air just like most of their "facts" that come from wherever!

[Hoser John]

NOT THE AIR R--IT WAS SCIENTIFICALLY EXTRAPOLATED UTILIZING THE LATEST GREATEST TECHNOLOGY AND REQUIRED HAZ/MAT LICENSES-they stuck their hand up their collective arses and out it came along with the big 7 tribes injun benjamins too John

[russau]

i agree but i didnt want to get kicked off this site or moderated.haha

[CalGoldDredger]

I see the great Dave Mckracken was right there helping them, pictures, heh. miners helping miners. Loose their rights.