Reconnaissance Survey of Mercury in Water, Sediment,

and Fish from U.S. Streams

ByBarbara Scudder, Lia Chasar, Nancy Bauch,

Dennis Wentz, Mark Brigham, David Krabbenhoft, Patrick Moran, William Brumbaugh, and Michelle

Lutz

U.S. Department of the InteriorU.S. Geological Survey

Fish Consumption Advisories – 2004

(source: USEPA National Listing of Fish Advisories)

Percentage of Lake Acres / River Miles with Mercury Advisories

(source: USEPA National Listing of Fish Advisories, 2004)

USGS Mercury Studies in RiversReconnaissance Survey of Mercury

1998 Pilot: 106 sitesKrabbenhoft and others (1999)Brumbaugh and others (2001)

1999-2002: 113 sites2004-5: 60 sites

Detailed Studies of Mercury Cycling and Bioaccumulation2003-4: 8 sites2006-7: 5 sites

Reconnaissance Survey Objectives Assess total mercury (THg) and methylmercury (MeHg) in

water and streambed sediment, and THg in fish

Span regional and national gradients in mercury source strength (deposition, mining) and factors that govern mercury cycling

Identify ecosystem characteristics that favor the production and bioaccumulation of MeHg

Explore environmental factors that may drive regional and national variations in fish mercury concentrations

Study Design – 1998 Pilot

Sites selected based on factors thought to be important in bioavailability of mercury, in priority:

wetland density in basin pH, sulfate, organic carbon Suspected or known mercury loading

Samples collected June through October 1998

Study Design: > 1998 Expand on site coverage from 1998 Base site network on:

Targeted settingsReference/noncultivatedCultivated agriculture UrbanMining (current or abandoned)

Factors thought to affect mercury methylationWetland density in watershed Water chemistry (pH, sulfate, DOC) Mercury loading – suspected or known

Ag Urban Forest Range

Land Cover/ Land Use of All U.S. Stream Basins (n=62,000) in Blue

and USGS Mercury Reconnaissance Basins (n=219) in Green

Perc

ent

Land

Cov

er/L

and

Use

0

20

40

60

80

100

Methods Surface-water

Single grab sample – center of stream flow Filtered and particulate MeHg, THg (unfiltered in 1998) pH, temperature, DO, DOC, sulfate

Streambed sediment Single composite sample Bulk (unsieved) – surface, depositional areas MeHg and THg Particle size, dry weight Acid volatile sulfide Loss on ignition (surrogate for organic carbon)

Methods (continued) Sampled Predator Fish

Electrofishing THg Target: 3-4 year old Largemouth bass Single-species composites (3-5 fish) Skin-off fillets Length, weight, age

Modeled fish (Wente, 2004) Accounts for variability among sample events and

sample characteristics Based on THg and length of sampled fish from sites 35.5 cm (14 in) largemouth bass and rainbow trout

Sampling Sites

Sampling sites

2004 - 2005

1998 - 20021998 - 2002, Mining-impacted

Surface water, whole(MeHg in ng/L)

0.004 - 0.0410.042 - 0.1050.106 - 0.2210.222 - 3.528Mining-impacted

Surface Water

Bed sediment(MeHg in ng/g)

0.01 - 0.180.19 - 0.630.64 - 2.602.61 - 38.18Mining-impacted

Bed Sediment

Sampled fish(THg in ppm, wet weight)

<0.1000.100 - 0.1990.200 - 0.299

0.300Mining-impacted

Sampled Fish

≥

Modeled fish, largemouth bass(THg in ppm, wet weight)

<0.1000.100 - 0.1990.200 - 0.299

0.300Mining-impacted

Modeled Fish

≥

Modeled FishSampled Fish

< 0.1000.100 - 0.1990.200 - 0.299≥ 0.300

(THg in ppm, wet weight)

Mining-impacted

Modeled FishSampled Fish

< 0.1000.100 - 0.1990.200 - 0.299≥ 0.300

(THg in ppm, wet weight)

Due to bioaccumulation and biomagnification, mercury in sampled fish was several orders of magnitude higher than the river water

10 10 10 10 10 10 10 10 10 1 10

Whole Water MeHg

Sediment MeHg

Sampled Fish THg

Mer

cury

conc

entr

ation

(ppm

)

-9-8

-7-6

-5

-4-3-2

-1

Mercury in sampled fish increased with methylmercury in water

r2 = 0.39, p<0.001

- 4

- 3

- 2

- 1

0

1

2

3

- 6 - 5 - 4 - 3 - 2 - 1 0 1 2

ln [MeHg in whole water] (ng/L)

ln [T

Hg in

fish

/leng

th]

(ug/

g /m

)

1998 ONLYBrumbaugh and others, 2001

Mercury in sampled fish increased with methylmercury in water

r2 = 0.15, p<0.001

- 4

- 3

- 2

- 1

0

1

2

3

- 6 - 5 - 4 - 3 - 2 - 1 0 1 2

ln [MeHg in whole water] (ng/L)

ln [T

Hg in

fish

/leng

th] (

ug/g

/m)

All Species1998- 2002

Relation stronger for Hg in sampled largemouth bass and water

r2 = 0.32, p<0.001

-4

-3-2

-1

0

12

3

-6 -5 -4 -3 -2 -1 0 1 2

ln [MeHg in whole water] (ng/ l)

ln [

THg

in fi

sh/l

engt

h] (u

g/g

/m)

Largemouth Bass1998- 2002

ConclusionsTotal mercury concentrations in fish

increased with increasing methylmercury concentrations in whole (unfiltered) water

Weak correlation between fish mercury and sediment methylmercury

Fish mercury concentrations exceeding the 0.3 ppm criterion were widespread, and particularly common in SE US streams and western mining-impacted streams.

Acknowledgments State and Tribal personnel USGS personnel - Technical assistance

NAWQA study unit personnel George Aiken, USGS-WRD, Boulder, CO Amanda Bell, USGS-WRD, Middleton, WI Rod DeWeese, USGS-BRD, Denver, CO Kerie Hitt, USGS-WRD, Reston, VA Steve Wente, USGS-WRD, Mounds View, MN

Contact info: Barb Scudder (bscudder@usgs.gov)US Geological Survey, 8505 Research Way, Middleton, WI 53711