1 PCB and PBDE Loads in Coyote Creek: Conceptual models and Estimates of Regional Small Tributaries...

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PCB and PBDE Loads in PCB and PBDE Loads in Coyote Creek:Coyote Creek:

Conceptual models and Estimates of Conceptual models and Estimates of Regional Small Tributaries LoadsRegional Small Tributaries Loads

Lester McKee, John Oram and, Jon LeatherbarrowLester McKee, John Oram and, Jon Leatherbarrow

Sources Pathways and Loadings WorkgroupSources Pathways and Loadings Workgroup

November 13November 13thth 2006 2006

San Francisco Estuary Institute

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HistoryHistory USGS dischargeUSGS discharge

WY 1999 – 2006 (ongoing)WY 1999 – 2006 (ongoing)

USGS suspended sediment dataUSGS suspended sediment data WY 2005WY 2005 WY 2006WY 2006

Regional Board TMDL laboratory funding Regional Board TMDL laboratory funding ($10k)($10k) WY 2005 PCB, PBDE, HgT, SSC, organic carbonWY 2005 PCB, PBDE, HgT, SSC, organic carbon

SFEI field team able to grab 7 samples during SFEI field team able to grab 7 samples during wading stage only during breaks from wading stage only during breaks from Guadalupe R. samplingGuadalupe R. sampling

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Field LocationField LocationItem #3


Coyote Ck. at Hwy 237USGS 11172175

Guadalupe R. at Hwy 101USGS 11169026

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MethodsMethods

Sampling Location

USGS Gage Shelter

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MethodsMethods Grab samples from mid depth at wading Grab samples from mid depth at wading

stagesstages

Regression between instantaneous SSC Regression between instantaneous SSC and PCB/PBDE concentrationsand PCB/PBDE concentrations

USGS 15 minute dischargeUSGS 15 minute discharge

USGS 15 minute SSC estimates from USGS 15 minute SSC estimates from GCLASSGCLASS

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Results - ConcentrationsResults - ConcentrationsItem #3


Sample SSC (mg/L) PCB (pg/L) PBDE (pg/L)

CC40 - 3,349 14,889

CC70 51 2,758 12,896

CC80 228 3,499 9,386

CC90 77 5,599 15,949

CC91 110 10,353 36,623

CC92 196 2,660 7,138

CC100 337 6,124 12,831

min - 2,660 7,138

max - 10,353 36,623

mean - 4,906 15,673

FWMC* - 9,305 29,852

* Based on annual load

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Regression EstimatorsRegression EstimatorsPCBsPCBs

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y = 17x

R2 = 0.89

y = 82x

R2 = 0.86

0

3,000

6,000

9,000

12,000

0 50 100 150 200 250 300 350 400

Suspended Sediment (mg/L)

To

tal P

CB

s (

pg

/L) Lower

Upper

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Regression EstimatorsRegression EstimatorsPBDEsPBDEs

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y = 286x

R2 = 0.81

y = 39x

R2 = 0.970

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

0 50 100 150 200 250 300 350

SSC (mg/L)

PB

DE

(p

g/L

)

Lower

Upper

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ProblemProblem How to we apply the two populations of How to we apply the two populations of

data (regression estimators) to published data (regression estimators) to published USGS daily sediment records?USGS daily sediment records?

Solution: Obtain 15 minute recordsSolution: Obtain 15 minute records

ErrorsErrors USGS accurately measures 15-minute USGS accurately measures 15-minute

dischargedischarge USGS only estimates 15 minute SSC based on USGS only estimates 15 minute SSC based on

rating relationships between flow and about rating relationships between flow and about 100 real measurements of SSC100 real measurements of SSC


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Results - LoadsResults - LoadsItem #3


2004 2005

Oct Nov Dec Jan Feb Mar Apr Total

Flow (Mm3) 3.3 1.3 4.9 6.9 10.3 13.1 7.5 47

PCB (g) 79 2 93 33 114 101 16 439

PBDE (g) 259 7 303 107 359 325 48 1,409

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Historic FlowHistoric FlowItem #3

0

50

100

150

200

19

71

19

73

19

75

19

77

19

79

19

81

19

83

19

85

19

87

19

89

19

91

19

93

19

95

19

97

19

99

20

01

20

03

20

05

Water Year

Flo

w (

Mm

3 )

y = 0.7211x

R2 = 0.9206

0

100

200

300

400

500

600

0 200 400 600 800

Guadalupe R. at Hwy 101 (cfs)

Co

yote

Ck.

at H

wy

23

7 (

cfs)

Average = 41 Mm3

MeasuredEstimated


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Average Load Estimate – Average Load Estimate – MethodMethod

PCBPCB

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y = 1.4612x2.8603

R2 = 0.94

y = 0.1565x2.606

R2 = 0.68

0.1

1

10

100

1000

10000

1 10 100

Monthly Flow (Mm3)

PC

B (

g/M

on

th)

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Average Load Estimate – Average Load Estimate – MethodMethodPBDEPBDE

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y = 4.4468x2.9083

R2 = 0.94

y = 0.4449x2.6514

R2 = 0.67

0.1

1

10

100

1000

10000

1 10 100

Flow (Mm3)

PB

DE

(g

/Mo

nth

)

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Estimated Average LoadsEstimated Average Loads

Using the range in flow experienced from Using the range in flow experienced from WY 1971 to WY 2006 we estimate the WY 1971 to WY 2006 we estimate the following:following:

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Flow

(Mm3)PCB(kg)

PBDE(kg)

Minimum ~2 ~0 ~0

Maximum ~174 ~12 ~40

Average ~41 ~1.5 ~5

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Guadalupe R.Guadalupe R.

Estimate of Average LoadsEstimate of Average Loads

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MethodsMethods

Develop a regression estimator using Develop a regression estimator using monthly flow and monthly loadmonthly flow and monthly load

Obtain historic monthly flow records for Obtain historic monthly flow records for the period 1971 – 2006the period 1971 – 2006

Estimate monthly loadsEstimate monthly loads

Calculate averageCalculate average

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Guadalupe Regression Guadalupe Regression EstimatorsEstimators

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y = 7.2596x1.2475

R2 = 0.80

0

200

400

600

800

1,000

1,200

0 10 20 30 40 50 60

Flow (Mm3)

PC

B (

g/M

on

th)

y = 18.082x1.2712

R2 = 0.89

0

500

1,000

1,500

2,000

2,500

3,000

0 10 20 30 40 50 60

Flow (Mm3)

PB

DE

(g

/Mo

nth

)


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Estimated Average LoadsEstimated Average Loads

Using the range in flow experienced from Using the range in flow experienced from WY 1971 to WY 2006 we estimate the WY 1971 to WY 2006 we estimate the following:following:

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Flow(Mm3)

PCB(kg)

PBDE(kg)

Minimum 2.8 ~0 ~0

Maximum 247.8 ~5 ~13

Average 58.2 ~1 ~2.5


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Coyote – Guadalupe Coyote – Guadalupe ComparisonComparison

Are the estimates Are the estimates reasonable?reasonable?

PBDE(kg)

PCB(kg) Ratio

Coyote Ck. 5 1.5 3.3

Guadalupe R. 2.5 1 2.5

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Area(below Dams) Ind Com Res

Open/Ag

PCBAverage

PCBMaximum

Coyote Ck. (km2) 335 15 16 83 222 3.41 26.75

Percentage (%)Percentage (%) 100 4 5 25 66

Guadalupe R. (km2) 236 30 30 137 38 0.26 1.22

Percentage (%)Percentage (%) 100 13 13 58 16

(mg/kg)


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Estuary Estuary Interface Interface

Pilot StudyPilot Study

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Leatherbarrow et al., 2002

CoyoteCreek

GuadalupeRiver

Water (pg/L) Wet 7,000 6,100

Dry 4,000 7,169

Sediment (ug/kg) Wet 45 43

Dry 46 31


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Estimating Total Estimating Total Regional Small Regional Small

Tributaries Loads:Tributaries Loads:

Extrapolation methods Extrapolation methods in the absence of in the absence of hydrologic modelshydrologic models

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MethodsMethods(PCBs and PBDEs)(PCBs and PBDEs)

1.1. Add Guadalupe and Coyote estimated Add Guadalupe and Coyote estimated average annual loads together and average annual loads together and scale by areascale by area

a)a) Total areaTotal areab)b) Excluding area above reservoirsExcluding area above reservoirs

2.2. Assume most load is associated with Assume most load is associated with urban area and scale the sum of urban area and scale the sum of Guadalupe and Coyote estimated Guadalupe and Coyote estimated average annual loads by an urban land average annual loads by an urban land use factor.use factor.

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MethodsMethods(PCBs only)(PCBs only)

3. 3. Use the sum of Coyote+Guadalupe Use the sum of Coyote+Guadalupe average loads to scale (calibrate) average loads to scale (calibrate) land use specific estimates of PCB land use specific estimates of PCB export derived by an extensive export derived by an extensive literature review and mass balance literature review and mass balance model (SFEI Prop 13). Apply these model (SFEI Prop 13). Apply these to land use statistics below to land use statistics below reservoirs for the Bay Area (Davis reservoirs for the Bay Area (Davis et al., 2000).et al., 2000).

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MethodsMethods(PBDEs only)(PBDEs only)

4. 4. Scale PBDE loads to PCB loads Scale PBDE loads to PCB loads using a ratio of 3:1using a ratio of 3:1

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Statistics for Statistics for CalculationsCalculations

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Area(km2)

Ind(km2)

Com(km2)

Res(km2)

Open/Ag(km2)

Guadalupe R. 414 30 30 137 216

Coyote Ck. 826 15 16 83 713

Bay Area Small Tributaries 6,650 374 404 1,726 4,147

AreaExcludingReservoirs

(km2)Ind

(km2)Com(km2)

Res(km2)

Open/Ag(km2)

Guadalupe R. 236 30 30 137 38

Coyote Ck. 336 16 15 83 222

Bay Area Small Tributaries 5,050 374 404 1,726 2,547


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Prop 13 export Prop 13 export estimatesestimates

(Ref: Mangarella et al., (Ref: Mangarella et al., 2006)2006)

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Scaled (Calibrated) Unit Scaled (Calibrated) Unit ExportsExports

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Land UseUnit Loading(g/km2/yr)

Unit LoadingNormalized

toOpen Space

Industrial 23.1 16

Commercial 9.6 7

Residential 2.9 2

Open/Agriculture 1.4 1


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Results Results Annual Average Loads Estimates for Annual Average Loads Estimates for

Total Bay Area Small TributariesTotal Bay Area Small Tributaries

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MethodPCB(kg)

Range*(kg)

PBDE(kg)

Range*(kg)

1a Area Ratio 13 40

1b Area Ratio (excl. reservoirs) 22 66

2 Area Ratio (urban only) 20 60

3 Calibrated unit export 21 63

Best estimate** 21 11-42 63 32-126

* Assumed - 50% error + 100% error based author’s hypothesis that Coyoteand Guadalupe are not representative of other Bay Area urban watershedsdue to large size and relatively low connectivity / drainage density ** Authors judgment


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1 PCB and PBDE Loads in Coyote Creek: Conceptual models and Estimates of Regional Small Tributaries...

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