Mercury, Turbidity and Suspended Sediments from Malakoff Diggins

Mercury, Turbidity and Suspended Sediments From Malakoff Diggins in
Humbug Creek
LOGO
HARIHAR
1GRADUATE
1
NEPAL ,
DR. CARRIE
2
MONOHAN
STUDENT, SP 12 GEOLOGICAL AND ENVIRONMENTAL SCIENCE, CSU CHICO, CA, 95926. 2SCIENCE DIRECTOR, THE SIERRA FUND, Nevada City, CA
INTRODUCTION
TURBIDITY, SUSPENDED SEDIMENTS, & MERCURY
Mercury mined from cinnabar ore found on the California coast range was transported
to the Sierra Nevada for use in gold mining. About 10 million pounds of mercury were
lost to environment during the California Gold Rush in
the
Yuba Bear watersheds alone (Churchill et.at. 2000).
Mercury is a neurotoxin that causes cognitive deficits at
low exposure levels and severe neurologic effects at high
levels of exposure (Nweke and Sanders, 2009). Methyl
mercury bio accumulates in the aquatic food chain and
leads to bio-magnification in large predatory fish
(O’Reilly et al., 2008) (Pic. 1).
Pic. 1: Mercury Cycle; Picture source: http://toxics.usgs.gov/icons/mercurybig.gif
SITE DESCRIPTION
Malakoff Diggins is one of the largest abandoned mine sites from the California Gold
rush and during its operation between 1866 and 1900, an estimated 39 million cubic
yards of rock were mined (DWR 1987). The mining site is located in Nevada County
on the western slope of the Sierra Nevada, about 14 miles northeast of Nevada City, 63
air miles northeast of Sacramento (Cahill, 1979). The historical literature on Malakoff
Diggins operation indicates that two tunnels from the mine pit site fed water into
Humbug Creek; the largest tunnel, the North Bloomfield tunnel is ~8,000 feet long and
200 feet below the surface. From field observations, it is assumed that the tunnel is
blocked somewhere before the opening. The second tunnel, Hiller tunnel, functions as
the primary drainage of the pit. Hiller tunnel has continuous flow throughout the year
Flow out of Hiller tunnel is highly turbid during storm conditions as shown in Picture 3
and 4.
METHODOLOGY
Biotic and abiotic components like soil particles, algae, plankton and microbes determine the optical property of water, known
as turbidity. These materials are typically in the size range of 0.004 mm to 1.0 mm (EPA, 2011). Suspended sediments are
often the primary cause of turbidity in water (Clifford, Richards, Brown, and Lane, 1995). Suspended sediments in water are
composed of insoluble products from weathering and biological activity (Zhong and Wang, 2007). Insoluble products from
weathering include primary minerals, mainly silicates and secondary minerals mainly clays; silica being more than 90% of the
Earth’s crust constitutes the large fraction of the suspended sediments (Zhong and Wang, 2007). The large amount of mercury
lost to the environment during operation of Malakoff gold mining resulted in Hg-contaminated sediments (Fleck and et al.,
2010). Concentration of THg, Hg(II)R increase with decreasing particle size of sediments (Fleck, 2010). About 16,000 cubic
meters of sediments consisting of silt and clay (<0.063 mm) are discharged from Malakoff Diggings into the South Yuba River
via Humbug Creek (Peterson, 1978). Rain splash, and unconcentrated sheetflow on the digging pit walls and floor are
responsible for erosion of about 23,500m3 of sediment per year from Malakoff Diggins, about half of which is composed of
silt and clay (Peterson, 1978). The sediments from the Malakoff Diggins site are rich in quartz (SiO2) and plagioclase (Na-Ca
feldspar); quartz is abundant in the sand size fraction (Fleck, 2010). Sediments are the major sink for Hg and inorganic Hg is
the dominant species of Hg in sediments (Zhong and Wang, 2007).
Pic. 3:
Highly
turbid
water
flowing
out of
Hiller
tunnel
from
Malakoff
Diggins
pit
during
storm
Pic taken
on
03/14/12
OBJECTIVE OF STUDY
Objectives of this study are to find the answer to the following questions about the
discharge from Malakoff Diggins: How does mercury concentration vary with turbidity?
How does mercury concentration vary with suspended sediments? How does suspended
sediments vary with turbidity?
Pic. 4:
showing
mixing
zone of
Highly
turbid
Diggins
Creek
and
slightly
turbid
Humbug
Creek
during
storm
event pic
taken on
03/14/12
Pic. 7: USI 446 to monitor water chemistry
Rainfall Monitoring:
STAGE & GRAB SAMPLE
Map 1: Hiller Tunnel, connecting
discharge from the pit, including the
pond, to Humbug Creek. Map is
taken from California state park
website.
Sample site selection: Sample sites were selected
on the basis of hydrology of the area. Water
samples were collected from three sites: Humbug
Creek above the confluence of Diggins Creek as a
background site (Site: Road 1), Diggins Creek at the
Hiller tunnel outlet (Site: Hiller 2), and about 300
feet below the confluence of the Humbug creek and
Pic. 2: Picture showing three sample sites in Google Map Diggins Creek Site: Gage3) (Picture 2).
Discharge Measurement: Discharge was measured by the USGS velocity area method (Wahl,
1995). A stage discharge relationship was developed for
the gage site (Gage 3) below the confluence of
Humbug and Diggins Creek.(Picture 5)
Water Sampling: Water samples for mercury and
suspended sediments were
Pic. 5: Velocity area method to measure discharge
collected by grab sampling
using ultra clean hand method
and by using US DH - 45 width
depth integrated sampling
technique. (Picture 6)
Pic. 6: US DH – 45 water sampler
Field Water Chemistry Monitoring: Temperature, pH, DO, and conductivity of water were
monitored at each site by YSI 556 meter during each grab
sampling event (Picture 7). Turbidity was measured at the Gage
site every 15 minutes by DTS – 12 turbidity sensor (picture 10).
Automated Sampling: Water samples were taken about 300 feet
below the confluence of Humbug Creek and Diggins Creek at the
gage 3 site using an ISCO auto sampler (SDI SAMP
6712) (Picture 8, 9 & 12). Samples taken with the ISCO were
analyzed for turbidity and total suspended solids.
2.5
Stage (ft)
Grab Samples
2
Rainfall data was
collected by installing
Onset RG – 2 Rain
gage near the Digging
Pit (Picture 11)
Pic. 8: Sample collected by ISCO
Pic. 9: Data logger for DTS – 12, ISCO & Pressure Transducer
Pic. 10: DTS – 12 Sensor in the Humbug Creek
Instrumental Error
1.5
1
0.5
0
The above graph is of stage reading from the pressure transducer (15 min readings)in Humbug Creek (green continuous line)
and corresponding date and time when grab samples were collected for mercury and suspended sediment measurements (blue
squares). Grab samples were also collected from sites Road 1 and Hiller 2 around the same time. So, each blue square
represents a total of 9 grab samples collected from three sites. Samples were sent to trace metal labs within 24 hours from time
of collection (results pending). Graphical analysis, including correlations between TSS and mercury concentration and TSS
and turbidity as well as mercury concentration and turbidity will be done to find out the relation between turbidity, suspended
sediments and mercury over a range of stream discharge. Width-depth integrated samples will be taken during storm
conditions and compared to grab samples for a range of stream discharge.
Pic. 11: Onset RG – 2 Rain Gauge
Pic. 12: ISCO AUTO Sampler, and different
sensors in gage - 3
BIBLIOGRAPHY
Cahill, Russell W. 1979 Malakoff Diggins State Historic Park Resource Management Plan, Department of Parks and Recreation, Sacramento.
Churchill, R.K., 2000, Contributions of mercury to California’s environment from mercury and gold mining activities Insights from the historical record, in Extended abstracts for the U.S. EPA-sponsored meeting, Assessing and
Managing Mercury from Historic and Current Mining Activities, November 28–30, 2000, San Francisco, CA
Clifford, N.J., Richards, K. S., Brown, R. A., and Lane, S. N., 1995. Scales of Variation of Suspended Sediment Concentration and Turbidity in a Glacial Meltwater Stream. Swedish Society for Anthropology and Geography 77
(45 – 65).
Department of Water Resources State of California 1987 Erosion Control at Malakoff Diggins State Historic Park. Report:86.
Fleck, Jacob A., et al. 2010 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. USGS:120
Frances Santos F. and et.al (2010), Distribution and mobility of mercury in soils of a gold mining region, Cuyuni river basin, Venezuela, Journal of Environmental Management.92(1268-1276)
Hanna Instruments HI 9829 http://www.hannainst.com/usa/prods2.cfm?id=027001&ProdCode=HI%209829
Harding, James 1975 Ecological Studies at Malakoff Diggins State Park. Report:42.
Laurier, F.J.G and et.al (2002), Mercury transformations and exchanges in a high turbidity estuary: The role of organic matter and amorphous oxyhydroxides, Pergamon: Geochimica et Cosmochimica Acta. 67 (3329-3345).
MacDonald, Lee, and Philip Williams & Associates 1989 Prospects for Reducing Sediment Yield from Malakoff Diggins State Historic Park. Consultants in Hydrology:36.
Navarro and et.al. (2008), Mercury Mobility in Mines Waste from Hg-mining areas in Almeria, Andalusia, Journal of Geochemical Exploration. 101 (236-246)
Nweke, Onyemaechi C., Sanders III, William H (2009), Modern Environmental Health Hazards: A Public Health Issue of increasing Significance in Africa, Environmental Health Perspectives. 117(6).
O’Reilly Stephan B. and et.al (2008), Mercury as a serious health hazard for children in gold mining areas, ScienceDirect Environmental Research. 107 (89-97).
Peterson, D. H. 1978. A Study of Modern Sedimentation at Malakoff Diggins State Historic Park, California, Thesis in Geology, University of California Davis.
Sarkar, D and et al., 1999. Adsorption of Mercury (II) by Variable Charge Surfaces of Quartz and Gibbsite. Soil Science Society of America Journal 63, (1626 – 1636).
Taylor, Thomas L. 1987
Humbug Creek fishery Evaluation. Report:16.
Wahl, Kenneth L. and et.al. Stream-Gaging Program of the U.S. Geological Survey. U.S. Geological Survey Circular 1123. Reston, Virginia, 1995
Zhong, Huan and Wang, Wen-Xion 2007. Effect of Sediment Conposition on Inorganic Mercury Partitioning, Speciation and Bioavailability in Oxic Surficial Sediments, ScienceDirect: Environmental Pollution: 151 (222-230).
Acknowledgments: Funding for this project has been provided by The Sierra Nevada Conservancy and the agencies of state of California. Many thanks also go to Dr. David Brown chair of GEOS department, CSU Chico, Dr. Carrie Monohan science director of The Sierra Fund and Jacob Fleck scientist, USGS for helping me to edit and design this poster. Thank you to all my friends in class who gave me feedback about this poster during class presentation.