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Mercury speciation in urban runoff: data from regional monitoring around San

Francisco Bay

Lester J. McKee (PhD) San Francisco Estuary Institute

4911 Central Avenue, Richmond CA 94804

DELTA TRIBUTARIES MERCURY COUNCIL

Tuesday February 26, 2013

12:30 p.m. – 4:30 p.m. 1 San Francisco Estuary Institute

Acknowledgements Funding • Clean Estuary Partnership • Regional Monitoring Program for Water Quality • Santa Clara Valley Water District • Santa Clara Valley Urban Runoff Pollution Prevention Program • Region 9 EPA • Region 2 Regional Water Quality Control Board • Proposition 13, Proposition 84

Many field staff from SFEI

Oversight • Sources Pathways and Loading Workgroup • Small Tributaries Loading Strategy Team • BASMAA • San Francisco Estuary Partnership

2 San Francisco Estuary Institute

San Francisco Bay Impetus

• Fishing advisory

• Impaired listing


Methylmercury in sediment (pbb) (Pulse, 2012)

Source: Pulse, 2012

Why urban runoff?


• We estimate about 50% of urban runoff is atmospherically derived so might be more bioavailable

• Legacy of industrial land use: sediments with up to 12 mg/kg Hg

• Mass balance for urban storm drains: – Ind : com : res : open/ag

– 7 : 6 : 2 : 1

Estimated average for Bay Area urban drainages = 20-30 ug/m2/y

TMDL targets


50%

90%

Watershed studies so far – sampling bias towards rainfall events

Watershed characteristics


Drainage Area (km2)

Impervious Area (%)

All Urban

(%) Res (%)

Ind (%)

Com (%)

Open/Ag/ Rangeland/ Forrest (%)

Urban impacted

Minimum 0.0162 13 33 2 5 3 3

Maximum 327 95 100 53 34 100 66

Mining impacted

Minimum 0.863 1

Maximum 154000 39

Relationships with SSC Z4LA (100% urban)


1

10

100

1000

1 10 100 1000 10000

Tota

l Me

rcu

ry (

ng/

L)

Suspended Sediment (mg/L)

Relationships with SSC


1

10

100

1000

10000

10 100 1000 10000

Tota

l Me

rcu

ry (

ng

/L)


BelCr

BorCr

CalCr

ESPS

GECr

LMarCr

LPenCr

PulCrS

PulCrN

Total mercury Concentrations


ID Watershed Max HgT

(ng/L)

11 Lower Penetencia Creek 19

22 Pulgas Creek Pump Station - N 27

21 Pulgas Creek Pump Station - S 28

12 Coyote Creek 58

23 Belmont Creek 59

5 Ettie Street Pump Station 73

24 Borel Creek 74

8 San Lorenzo Creek 77

18 Calabazas Creek 89

20 Stevens Creek 121

17 San Tomas Creek 129

9 Zone 4 Line A 147

19 Sunnyvale East Channel 151

6 Glen Echo Creek 179

3 Walnut Creek 181

4 Santa Fe Channel 217

7 San Leandro Creek 477

13 San Pedro Storm Drain 499

10 Zone 5 Line M 1740

Range: 19 – 1790 ng/L 92x variation

Water flow and sediment loads in

Bay Area watersheds


Unit flow varies about 4x Unit sediment loads varies 100 x (25 - 3000 t/km) Therefore we should see >25x variation between watersheds

So how to we rank watersheds for management

effort?


• Best to normalize for sediment or better measure particle conc. Directly

• Range: 0.08 – 0.85 mg/kg

ID Watershed

Max HgT

(ng/L)

MedianHgT:SSC (mg/kg)

3 Walnut Creek 181 0.08 18 Calabazas Creek 89 0.15 11 Lower Penetencia Creek 19 0.16 24 Borel Creek 74 0.18

8 San Lorenzo Creek 77 0.18 9 Zone 4 Line A 147 0.22

20 Stevens Creek 121 0.25 23 Belmont Creek 59 0.25 12 Coyote Creek 58 0.25 17 San Tomas Creek 129 0.26 10 Zone 5 Line M 1740 0.31 19 Sunnyvale East Channel 151 0.35

6 Glen Echo Creek 179 0.36 22 Pulgas Creek Pump Station - N 27 0.45 13 San Pedro Storm Drain 499 0.63

4 Santa Fe Channel 217 0.70 5 Ettie Street Pump Station 73 0.78

21 Pulgas Creek Pump Station - S 28 0.80 7 San Leandro Creek 477 0.82

Watershed ranking for management focus – HgT

Ranking – Pulgas S.

– San Leandro

– Ettie

– Santa Fe

– Pulgas N.

– Glen Echo

– Z5 Line M


Sediment yield

• Less effect

since ~ 50% is

atmospheric

Ranking for management based on the unit loading method – leverage!

14

1 10 100 1000

Coyote Creek at Hwy 237 (Large mixed land use urban andag)

Sacramento River at Mallard Island (V. large mixed land use)

Zone 4 Line A (Hayward) (Small 100% urban/ 30% industrial)

San Lorenzo Creek (Moderate - mixed land use urban andag)

Lower Marsh Creek (Moderate - agricultural with mininginfluence)

Urban San Jose between gauges (90% urban - 7% industrial)

Sunnyvale East Channel (Small urban)

Walnut Creek (Large - mixed land use urban and ag)

Ettie Street Pump Station (Small 100% urban with legacyheavy industrial)

Guadalupe River at Hwy 101 (Large urban and miningimpacted)

Guadalupe River at Hwy Almaden Expsswy (Moderate sizedmining impacted)

Total Hg (ug/m2/y)

Ranking areas within watersheds based on soil sampling (~650 samples to-date) (BASMAA collecting more presently)


Number of sites

in patch

Hg concentration (mg/kg) Patch description (centroid x-streets)

Average Minimum Maximum

2 1.82 1.73 1.91 Beatty Ave & Hwy 101 San Francisco

2 1.45 0.20 2.70 11th St & Decoto Rd, Union City

2 0.80 0.35 1.24 E Grand Ave & Grandview Dr South SF

26 0.78 0.08 12.54 Cabot Blvd & W Winton Ave, Hayward

20 0.78 0.09 6.23 S 10th St & Burke St, San Jose

6 0.70 0.18 1.99 Pierce St & Central Ave, Albany CA

4 0.67 0.15 1.21 Glen Ave & Piedmont Ave, Oakland

5 0.62 0.14 1.86 Curtola Pkwy & Solano Ave, Vallejo

3 0.56 0.32 0.98 E 3rd St & Columbia St, Pittsburg

20 0.56 0.08 1.39 S 4th St & Cutting Blvd, Richmond

22 0.56 0.08 1.58 Magnolia St & 30th St, Oakland

2 0.54 0.31 0.78 26th Ave & E 27th St, Oakland

12 0.54 0.10 4.26 S 1st St & Union St, San Jose

2 0.50 0.31 0.68 Marina Vista Ave & Shell Ave, Martinez

6 0.46 0.05 1.84 Shoreway Rd & Cormorant Dr, Belmont

Mercury speciation

16

0.1

1

10

100

1 10 100 1000

SSC (mg/L)

Perc

en

t T

ota

l H

g

(%)

Urban Temporal dynamics (within years)

(San Pedro, Storm Drain (San Jose)

65% HgD(%)

MeHgT(%)

1%


0.01

0.1

1

10

100

1000

1 10 100 1000

SSC (mg/L)

Pe

rce

nt

To

tal

Hg

(%)

Urban Temporal dynamics (within years) (Z4LA, Storm Drain (Hayward)

HgD(%) 59%

MeHgT(%) 15%


Dec

??

or ??

Annual MeHg variation

(Hypothesis)

Acid labile Hg in Z4LA

• Refers to the inorganic component that is easily reducible to Hg0 using SnCl2

• 92% particulate, 0.9% methylated, and 0.8% acid labile

• Yield of MeHg = 0.045 ug/m2/y similar to many wetland dominated watersheds

• June 25th 2008, 5% MeHgD and 77% HgR = 83% bioavailable!

0.1

1

10

100

1 10 100 1000 10000Aci

d r

ed

uci

ble

Hg

(%)

Suspended sediment (mg/L)

Dry season up to 77%

Mercury – land use relationships? Preliminary thoughts…


HgT MeHgT Max HgT Area Imperv.

Old Urban

Old Ind.

Ag/ Open Res. Ind. Com.

Ind. + Com.

All Urb.

HgT (ng/mg) 1

MeHgT (mg/kg) 0.50 1

Max HgT (ng/L) 0.04 -0.08 1

Drainage Area (km2) -0.43 -0.22 -0.13 1

Imperviousness (%) 0.67 0.47 -0.17 -0.58 1

Old Urban (%) 0.78 0.41 -0.16 -0.49 0.69 1

Old Industrial (%) 0.48 -0.10 -0.14 -0.27 0.62 0.58 1

Ag/ Open (%) -0.46 -0.26 0.18 0.73 -0.82 -0.53 -0.40 1

Residential (%) -0.41 -0.52 0.11 0.05 -0.60 -0.43 -0.61 0.16 1

Industrial (%) 0.23 -0.43 -0.09 -0.45 0.31 0.36 0.22 -0.50 0.33 1

Commercial (%) 0.50 0.61 -0.16 -0.41 0.85 0.52 0.57 -0.66 -0.81 -0.16 1

Industrial + Commercial (%) 0.57 0.47 -0.19 -0.56 0.95 0.64 0.64 -0.82 -0.69 0.18 0.94 1

All Urban (%) 0.46 0.26 -0.18 -0.72 0.82 0.53 0.40 -1.00 -0.16 0.50 0.65 0.82 1

Example relationship

• Correlation matrix in encouraging – might get a decent statistical model

• So is it many small point sources or one non-point source (air deposition)?


y = 0.70x + 0.05 R² = 0.45

0.00

0.20

0.40

0.60

0.80

1.00

0% 25% 50% 75% 100%

Tota

l mer

cury

no

rmal

ized

to

su

spen

ded

sed

imen

t (m

g/k

g)

Impervious area in relation to watersed area

Simplifying it down to an easier message

23

• Built-out urban

• Hydro-modification

3-4 fold increase

• Total Hg: 2-4 fold

increase

San Francisco Estuary Institute

Land use relationships – multi-metric approach

• Normal transformed particle ratio data, 17 land use/cover attributes

• Pearson correlation, principal components analysis, and linear regression


Parameter Abbreviation N Median Maximum CV (%) Zero values (%) Transform b

Area (km2) area 206 4.1 960.2 392 0 Log

Imperviousness (%) imperv 206 42 90 57 0 Arcsine(Sqrt)

1954 Urban (%) oldurb 206 31 101 c 91 17 Sqrt

1954 Industrial (%) oldind 206 0 37 208 33 Log

1974 Urban (%) oldurb74 206 86 101 c 54 7 Arcsine(Sqrt)

1974 Industrial (%) oldind74 206 2 67 177 22 Log

Agriculture (%) ag 206 0 18 510 80 Log

Commercial high density (%) cohigh 206 4 95 174 18 Log

Commercial low density (%) colow 206 4 100 216 18 Log

Industrial (%) oldind 206 3 80 165 15 Log

Null (%) null 206 0 40 311 34 1/Sqrt

Open infiltrative (%) openinf 206 5 100 147 18 Cube Root

Open impervious (%) opencomp 206 6 100 135 7 Log

Residential high density (%) reshigh 206 18 68 91 18 Arcsine(Sqrt)

Residential low density (%) reslow 206 1 53 192 29 Log

Transportation (%) trans 206 15 98 89 4 Sqrt

Water (%) water 206 0 55 319 37 Log

Total mercury (ng/mg) 22 0.33 4.5 145 0 1/Sqrt

Methylmercury (ng/mg) 18 0.0019 0.008 88 0 Log

PCBs (pg/mg) 22 61 1,403 166 0 Log

PBDEs (pg/mg) 8 192 453 62 0 Sqrt

PAHs (pg/mg) 8 3,953 130,241 179 0 Log

TOC (mg/mg) 19 0.037 0.17 82 0 Log

Land use relationships – results principal components

• Land use / cover variables strong interrelated

– PC1: imperviousness and old

urban/industrial

– PC2: watershed area and low density residential

– PC3: negatively correlated with industrial

– PC4: negatively correlated with open space, water, and undefined cover


Principal components Parameter Loading 1 2 3 4

Area 0.52 Imperviousness 0.38 -0.16 1954 Urban 0.33 1954 Industrial 0.30 -0.37 1974 Urban 0.38 0.23 1974 Industrial 0.31 -0.45 Agriculture -0.13 0.30 Commercial high density 0.30 0.13 0.18 Commercial low density 0.18 0.33 Industrial 0.20 -0.58 Null -0.17 -0.61 Open infiltrative -0.32 0.21 -0.29 Open impervious 0.20 -0.45 Residential high density 0.21 0.35 0.19 -0.14 Residential low density 0.49 0.18 Transportation 0.28 0.19 Water -0.21 -0.60

Variance explained (%) 28.6 16.0 11.8 7.4

Cumulative variance (%) 29 45 56 64

Land use relationships – results correlation


• Pearson correlation

• Linear regression model

Total mercury Methylmercury PCBs PBDEs PAHs

Methylmercury 0.68 (18) PCBs 0.65 (22) 0.48 (18) PBDEs 0.72 (8) 0.90 (7) 0.54 (8) PAHs 0.70 (8) 0.86 (7) 0.54 (8) 0.65 (6) TOC 0.35 (19) 0.27 (18) 0.45 (19) 0.57 (7) 0.63 (7)

Pollutant PCA model PCA R2 Imperviousness R2 Area R2 Industrial R2

THg +PC1 0.32 0.37 0.24 NS MeHg NS NS NS NS NS PCBs +PC1 0.57 0.43 0.18 0.35 PBDEs -PC3 0.64 NS NS 0.58 PAHs -PC2 0.75 0.90 0.68 NS TOC -PC3 0.26 0.28 NS 0.20

Pilot study to investigate structural retrofit treatment options

0%

20%

40%

60%

80%

100%

Z4-201

(33ng/L)

Z4-203

(36ng/l)

Z4-204

(38ng/l)

Z4-205

(34ng/l)

RS-1003

(38ng/L)

RS-1004

(35ng/L)

<25 um

25-75 um

>75 um


Management implications

• During first flush and peak flow • Most mercury transported in particulate form

• settling is a treatment option

• First flush even contains a greater portion of MeHg

• During dry weather flows

– Most mercury transported in dissolved and methylated phases

– Difficult to treat


Southern SF Bay mining impacted systems


New Almaden Historic Mining District (Now the Almaden Quicksilver County Park)

• Largest producer of Hg

in North America

• Peak Production 1865: 1.6 million kg

• Total Production: 1845 – 1975: 38 million kg

0.0

0.5

1.0

1.5

2.0

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n k

g)

San Francisco Estuary Institute 30

Loadings per year - Mercury

San Francisco Estuary Institute

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ota

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erc

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(kg

)

Water Year (Ending September 30th)

Mean = 125 kg

Methylmercury <<1%

Speciation in SF Bay mining impacted systems


Hg-T (ng/L)

HgD (%)

MeHgT (%)

Hg-R (%)

Guadalupe River at Hwy 101 MDL -18,700 3* 0.4*

Alamitos Creek 58 – 110,000 7** 0.07**

McAbee Ck at Little Stone Bridge 470 - 2,800 5**

Sacramento River at Mallard Island 3.5 - 75 27%* 1.6* 6.1*

* Weighted average ** Median

0.1

1

10

100

1 10 100 1000


Perc

en

t T

ota

l H

g

(%)

Mining Sources (New Almaden, Guadalupe R.)

Temporal dynamics (within years)

HgD(%)

MeHgT(%)

15%

2%


Hg removal from SCVWD facilities


Year Mercury Removed

2004-2005 390 kg

2005-2006 31 kg

2006-2007 43 kg

2007-2008 100 kg

2008-2009 46 kg

2009-2010 327 kg – 1632 kg*

*Assuming that 12,000 cubic yards of soil has been removed at

20mg/kg – 100mg/kg, the amount of mercury removed would be in the

range of 327 kg Hg – 1632 kg Hg.

Next steps: loads monitoring (Water Year 2013 and 2014)

• Richmond Pump Station – Contra Costa County

• Pulgas Pump Station – San Mateo County

• East Sunnyvale Channel – Santa Clara County

• Guadalupe River – Santa Clara County

• Lower Marsh Creek – Contra Costa County

• San Leandro Creek – Alameda County


LID – a management solution?


• Daly City rain garden – HgT 39-64% reduction

– MeHg production

• El Cerrito rain garden • HgT inconclusive/mixed results

• MeHg 34-69% reduction

• Potential for collaboration is high – Plan to recruit science oversight

– Others could piggyback monitoring

Take home messages


• San Francisco Bay fish are contaminated: Water Board has called for control of urban and mining runoff

• Mercury sources and speciation has a direct bearing on source and treatment control options – Either particle concentrations or unit area loads are suitable for ranking

watersheds for management (finding high leverage areas)

– Urban and mining annual load <8% bioavailable but more bioavailable in spring and summer

• Multiple management options are being explored in relation to stormwater permits

san francisco estuary institute 4911 central avenue ... · (basmaa collecting more presently) san...

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