Contaminant Metals in Boston Harbor: Processes Influencing long-term fate Bill Martin Linda Kalnejais Mike Bothner
Jan 21, 2016
Contaminant Metals in Boston Harbor:Processes Influencing long-term fate
Bill MartinLinda KalnejaisMike Bothner
Study Site:Hingham Bay2000 - 2008
Ag, Pb, and Cu:1980 - 2002
8
6
4
2
20001995199019851980
Year
140
120
100
80
6.0
5.0
4.0
Cu
Ag
Pb
Al
Fe
Boston HarborStation 8
25
20
15
10
5
0
12080
Cu (ppm)
25
20
15
10
5
0
108642
Ag (ppm)
25
20
15
10
5
0
16012080
Pb (ppm)
Concentration vs. depth : 2002
Surface Sediments: Concentration vs. time
Cu, Ag, and Pb
All are associated with organic matter : Cu > Ag, Pb
All form stable complexes and sparingly soluble solid phases with S(-II)
All coprecipitate with / sorb to Fe oxides : Pb > Ag, Cu
Depth Distributions of Sedimentary ProcessesHingham Bay Site
(not to scale)
Data Treatment:Averaged and smoothed profiles
25
20
15
10
5
0
200150100500
Fe (µM)
HB July 02
25
20
15
10
5
0
0.80.60.40.20.0
Ag (nM)
HB July 02
25
20
15
10
5
0
Depth (cm)
3002001000Fe
2+ (µM)
January
25
20
15
10
5
0
Depth (cm)
10008006004002000
H2S (µM)
January July Sept./Oct
Fe and S cyclingWinter
25
20
15
10
5
0
Depth (cm)
10008006004002000
H2S (µM)
January July Sept./Oct
25
20
15
10
5
0
Depth (cm)
3002001000Fe
2+ (µM)
January July
Fe and S cyclingSummer
25
20
15
10
5
0
Depth (cm)
10008006004002000
H2S (µM)
January July Sept./Oct
25
20
15
10
5
0
Depth (cm)
3002001000
Fe (µM)
January July Sept./Oct.
Fe and S cyclingLate Summer / Early Fall
Trace Metal Cycling: Cu - Winter
25
20
15
10
5
0
3002001000Fe
2+ (µM)
January
25
20
15
10
5
0
50403020100
Cu (nM)
Trace Metal Cycling: Cu - Summer
25
20
15
10
5
0
3002001000Fe
2+ (µM)
January July
25
20
15
10
5
0
50403020100
Cu (nM)
January July
Trace Metal Cycling: Cu - Late summer
25
20
15
10
5
0
3002001000
Fe (µM)
January July Sept./Oct. 25
20
15
10
5
0
50403020100
Cu (nM)
Compare: Cu and Ag
25
20
15
10
5
0
50403020100
Cu (nM)
25
20
15
10
5
0
0.80.60.40.20.0
Ag (nM)
January July Sept./Oct.
Compare: Cu and Pb
25
20
15
10
5
0
12840
Pb (nM)
JanuaryJuly Sept./Oct.25
20
15
10
5
0
50403020100
Cu (nM)
The sedimentary environment
Sediment Resuspension:Experimental Setup
Sediment Resuspension:Mass resuspended vs. bottom stress
Solid Phase Metals
Dissolved metals
Longer-term releasefrom resuspended particles
Incubations: Filled : particle incubations Open: filtered controls
Bottom stress at theHingham Bay Site
80
60
40
20
0
Frequency (events/year)
0.400.350.300.250.200.150.10
Shear stress (N/m2)
Including Sediment-Seawater exchange in the budget for Cu in Boston Harbor
4000
3000
2000
1000
0
Input to harbor (kg/yr)
TributariesAtmosphereGroundwaterAirportCSO
StormwaterErosion - fastErosion - slowDiffusion
Sum: dissolvedSolid phase
Cu
Conclusions
Remobilization of contaminant metals, deposited earlier, may be asignificant source of metals to Boston Harbor.
Ongoing work: Complete analyses and interpretation of Boston Harbor and Mass Bay experiments. To date: Kalnejais (2005) - PhD Thesis (and presentations at AGU, ASLO, GSA) Oates (2008) MS Thesis Morford et al. (2007) Kalnejais et al. (2007) Martin and Kalnejais (2007)
Future work:
Update and extend contaminant metal budgets for Boston Harbor
Determine distributions of particulate metals in Mass. Bay - especially after important resuspension events