Advances in Understanding Pollutant Mass

LoadingsLester McKee

Jon Konnan, Richard Looker, Nicole David, Jay Davis

Article on Page 77 of the Pulse

Why Measure Loadings?• Fish consumption advisories since 1993

– San Francisco Bay is listed as impaired for a range of contaminants

• Initially loadings information was generated to develop TMDL project reports written by the Water Board– More loadings information– Measurement of progress towards targets

What are the priority contaminants?

Substance PriorityMercury and PCBs Top

Polybrominated diphenylethers (PBDEs) High

Current use pesticides (pyrethroids), dioxins, selenium, OC pesticides, copper, nickel, PAHs Medium

Silver, arsenic, cadmium, chromium, lead, zinc, organophosphate pesticides, nutrients Low

What are the Main Sources and Pathways?

Guadalupe River

Urban Stormwater

In-Bay contaminated sites

Focus is on the larger pathways that are deemed potentially controllable

• Sacramento River

• Guadalupe River

• Zone 4 Line A

What Stormwater Loading Studies are ongoing?

Sacramento River at Mallard Island near Pittsburg

Sacramento River at Mallard Island near Pittsburg

Sacramento River at Mallard Island near Pittsburg

Sacramento River at Mallard Island near Pittsburg

Concentration on particles(Low – moderate flow)

Concentration on particles(Large storms)

0

1

2

3

19

95

19

96

19

97

19

98

19

99

20

00

20

01

20

02

20

03

20

04

20

05

20

06

Water Year

Su

sp

en

de

d S

ed

ime

nt

(mill

ion

me

tric

t)

Mean = 1 million metric t

Loadings per year - Sediment

Journal of Hydrology: McKee et al., 2006

Loadings per year – Mercury

0

200

400

600

19

95

19

96

19

97

19

98

19

99

20

00

20

01

20

02

20

03

20

04

20

05

20

06

Water Year

Me

rcu

ry (

kg

)

Mean = 210 kg

ET&C: David et al., in review

Loadings per year - PCBs

0

5

10

15

20

251

99

5

19

96

19

97

19

98

19

99

20

00

20

01

20

02

20

03

20

04

20

05

20

06

Water Year

PC

Bs

(k

g)

Mean = 9.6 kg

Guadalupe River at Hwy 101 in San Jose

Guadalupe River at Hwy 101 in San Jose

Guadalupe River at Hwy 101 in San Jose

Mercury on Particles

PCBs on Particles

Urban stormwater

Non-urban stormwater

Loadings per year - Sediment

02,0004,0006,0008,000

10,00012,00014,000

2003 2004 2005 2006

Water Year

Su

sp

en

de

d s

ed

ime

nt

(me

tric

t)

Mean = 14,000 metric t

Loadings per year - Mercury

-10

20

50

80

110

140

2003 2004 2005 2006

Water Year

Me

rcu

ry (

kg

)

Mean = 130 kg

Methylmercury <<1%

Loadings per year - PCBs

0.0

0.5

1.0

1.5

2.0

2003 2004 2005 2006

Water Year

PC

Bs

(k

g) Mean = 0.9 kg

PBDEs = 2.5x greater

Zone 4 Line A Tributary at Cabot Blvd. in Hayward

Zone 4 Line A Tributary at Cabot Blvd. in Hayward

Zone 4 Line A Tributary at Cabot Blvd. in Hayward

Loadings normalized per unit area per year

Area

(km2)

SuspendedSediment

(t/km2)

TotalMercur

y(g/m2)

Methyl-Mercur

y(g/m2)

Sum ofPCBs

(g/m2)

Sum ofPBDEs(g/m2)

DDT(g/m2)

Z4LA (WY 2007) 4.5 24 5.6 0.16 3.2 9.0 3.7

GuadalupeRiver(WY 2004) 236 36 64 0.088 3.3 6.7 3.3

Statisticallydifferent? Yes Yes Yes No No No

What have we learned?

Mercury

What have we learned?

PCBs

Mercury• Which watersheds are most contaminated?

• What are the loadings from specific watersheds and the region as a whole– Currently based on sediment Hg concentrations and

out-dated estimates of regional sediment loads

• Little information on mercury speciation– Methylmercury– Reactive mercury

Remaining Questions and Progress

PCBs• Little information on loadings from small

heavily industrialized watersheds– Mainly near the Bay margin– Focus on “old industrial”

• Which watersheds are most contaminated?

• What are the sources and processes of release?

Remaining Questions and Progress

Remaining Questions and Progress• PBDEs and OC pesticides

– One box model paper published in Environment International (Oram et al 2008)

– Penta and Octa banned – when will the loads go down - will the Bay recover?

• Dioxins and pyrethroid pesticides– No information on urban loadings– Little to no information on other pathways

• Selenium, Copper, Nickel, PAHs– Not recently discussed

All contaminants

• Are there “high leverage” areas or processes on the Bay margin where contaminants impact the base of the food web

• What is the linkage between watershed loadings and “hotspots” or “high leverage” areas on the Bay margin

What are the remaining questions?

• Small Tributaries Loadings Strategy– Being developed now

• Mercury Strategy (page 4 of the Pulse)– First strategy to be developed

• Dioxin Strategy– Priorities vary by stakeholder – very

expensive so still debate over funding

• Modeling Strategy– Being developed now

Planning efforts to prioritize and address data gaps

1) Impairment• Which are the “high-leverage” small tributaries that

contribute most to Bay impairment?

2) Loading• What are the concentrations and average annual loads of

pollutants of concern from small tributaries?

3) Trends• How are concentrations or loads of pollutants of concern

from small tributaries changing on a decadal scale?

4) Support for Management Actions• What are the projected impacts of management actions and

where should management actions be implemented?

Small Tributaries Loading Strategy

A three page document that includes:

• Key questions and priorities• Guiding principles• A timeline• Recommended methods

Summary• Our understanding of pollutant mass loads has

changed considerably

– We now have accurate measurements of loads in three watersheds

• But there are still many questions

• Through time the needs for information are becoming more explicit and the RMP is adapting to new needs

– Constant re-evaluation of the management questions– 5-year plans for the workgroups and the program as a

whole– Focus strategy documents (contaminant or issue specific)

Acknowledgements

• Mercury labs– MLML– UCSC– Brooks Rand

• Trace organics lab : AXYS

• Sediment studies– USGS– USDA– RiverMetrics

• Field staff– SFEI– UCSC– Water Board