measurements of mercury concentrations and loads in a large river system tributary to san francisco...
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Measurements of Mercury Concentrations and Loads in a Large River System Tributary to San Francisco Bay, California, USA
Nicole David, SFEILester McKee, SFEIItem #3
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Study Design
Hg, PCBs, PAHs, oc-pesticids, PBDEs, Se conc. during high flow events
Continuous sediment measurements
Quantify pollutant load estimates
Include DAYFLOW data from DWR
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Water Year
66 71 76 81 86 91 96 01 06
Del
ta O
utf
low
(m
3/s
)
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
Daily Delta Discharge
90% of the flow occurred in 51% of the days
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Water Year
96 97 98 99 00 01 02 03 04 05 06
Dai
ly S
SC
Lo
ad (
t)
0
50000
100000
200000
250000
Daily Sediment Load
Net transport occurred on just 70 daysor 1.6% of the time
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Dec/05 Jan/06 Feb/06 Mar/06 Apr/06 May/06 Jun/06
Flo
w (
m3 /s
)
0
2000
4000
6000
8000
10000
12000
Delta OutflowYolo BypassSacramento River
TH
g in
ng
/L
0
10
20
30
40
50
Mercury Concentration
Flow Patterns and Mercury Concentrations
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SSC (mg/L)
0 20 40 60 80 100 120
To
tal H
g (
ng
/L)
0
5
10
15
20
25SSC vs Hg < 4,247 m3/s SSC vs Hg with EC>2 mS/cmData Outliers
y=0.11x+3.08R2=0.78
y=0.29x-2.17R2=0.78
SSC (mg/L)
30 40 50 60 70 80 90
Hg
(n
g/L
)
0
5
10
15
20
25
40
60
80
SSC vs Hg > 4,247 m3/sData Outliers
y=0.22x+4.31R2=0.66
Flows between 0 and 150,000 cfs
Flows between 150,000 and 370,000 cfs
Particulate Hg Concentration over Time
0
0.2
0.4
0.6
0.8
1
1.2
24-D
ec-0
5
29-D
ec-0
5
3-Ja
n-06
8-Ja
n-06
13-J
an-0
6
18-J
an-0
6
23-J
an-0
6
Time
Pat
icu
late
Co
nce
ntr
atio
n [
mg
/kg
]
Particulate Hg Concentration over Time
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Water Year Flow (Mm^3) Sediment (Mt) Error +/- (Mt) Hg (kg) Error +/- (kg)1995 51,559 2.58 0.83 599 2221996 31,436 1.01 0.32 211 781997 42,307 2.24 0.72 579 2141998 53,639 2.42 0.77 538 1991999 27,805 0.84 0.27 163 602000 22,394 0.66 0.21 142 532001 8,565 0.26 0.08 53 202002 11,303 0.31 0.10 61 232003 17,330 0.55 0.17 101 372004 18,577 0.64 0.20 131 482005 18,588 0.42 0.13 86 322006 50,020 1.99 0.64 484 179
Average 29,460 1.16 0.35 262 97
Loads from the Delta
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Hg Sources
• Watershed (Urban, Ag, etc.)
• Air Deposition (indirect and direct)
• Historic
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12
2
3
5
6
7
9
10
11
12
13
14
4
80
2
4
6
8
10
0.1
1.0
10.0
100.
0
1,00
0.0
10,0
00.0
100,
000.
0
1,00
0,00
0.0
10,0
00,0
00.0
Watershed Size
Yie
ld R
ate
(g
/km
2/y
ea
r)
Comparison of Yield Rates Worldwide1 Negro and Solimões River, Brazil2 MacKenzie, Canada3 Sacramento River, CA 4 Potamac, MD 5 Headwater Mississippi, MN 6 Minnesota River, MN7 São Francisco, Brazil
8 St. Croix River, MN9 Blue Earth, MN10 Rum River, MN 11 Le Sueur, MN 12 Sudbury River, MA (past superfund site) 13 Sudbury River, MA 14 Catchment in Sweden
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700 kg/yr +/- 50%
700 kg/yr +/- 50%
wet deposition
WS
MI 262 kg/yr +/- 37%
154 kg/yr +/- 50%in mixed WS
Mining ?
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