Metal Deposition in Baldcypress Tree Rings: Nickel, Copper, Chromium, Manganese and Iron Margaret S....
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Transcript of Metal Deposition in Baldcypress Tree Rings: Nickel, Copper, Chromium, Manganese and Iron Margaret S....
Metal Deposition in Baldcypress Tree Rings:
Nickel, Copper, Chromium, Manganese and Iron
Margaret S. Devall1, Leonard B. Thien2, and George C. Flowers2
1USDA Forest Service, Center for Bottomland Hardwoods Research, P.O. Box 227, Stoneville, MS
2Tulane University, New Orleans, LA
Methods
• Cypress trees cored along bayou and reference area and chronology developed
• 5-year increments ground and pressed into pellets
• X-ray fluorescent spectrometer used to analyze samples
• Concentrations presented in spatial and temporal dimensions
Results
• First, levels of metals presented with respect to proximity to point source
• Second, history of pollution documented
NICKEL
0
2
4
6
8
10
12
14
0-1
0
10
--2
0
20
-30
40
-50
50
-60
80
-90
10
0-1
10
12
0-1
30
13
0-1
40
14
0-1
50
15
0-1
60
BAYOU STATIONS
PP
M
Mean level of Ni is 6.6 at Stations 0-60 and 4.5 at Stations 80-160.
NICKEL CONCENTRATION IN BALDCYPRESS FROM BAYOU TREPAGNIER AND STINKING BAYOU
0
2
4
6
8
10
12
14
16
190
5
191
0
191
5
192
0
192
5
193
0
193
5
194
0
194
5
195
0
195
5
196
0
196
5
197
0
197
5
198
0
198
5
199
0
199
5
TREE RING YEARS
PP
M
BT/Ni
SB/Ni
COPPER
0
0.5
1
1.5
2
2.5
3
3.5
4
0-1
0
10
--2
0
20
-30
40
-50
50
-60
80
-90
10
0-1
10
12
0-1
30
13
0-1
40
14
0-1
50
15
0-1
60
BAYOU STATIONS
PP
M
Mean level of Cu is 2.4 at Stations 0-60 and 2.8 at Stations 80-160.
COPPER CONCENTRATION IN BALDCYPRESS FROM BAYOU TREPAGNIER AND STINKING BAYOU
0
2
4
6
8
10
12
14
190
5
191
0
191
5
192
0
192
5
193
0
193
5
194
0
194
5
195
0
195
5
196
0
196
5
197
0
197
5
198
0
198
5
199
0
199
5
TREE RING YEARS
PP
M
BT/Cu
SB/Cu
CHROMIUM
0
2
4
6
8
10
12
0-10 10--20 20-30 40-50 50-60 80-90 100-110
120-130
130-140
140-150
150-160
BAYOU STATIONS
PP
M
Mean level of Cr is 6.6 at Stations 0-60 and 7.4 at Stations 80-160.
CHROMIUM CONCENTRATION IN BALDCYPRESS FROM BAYOU TREPAGNIER AND STINKING BAYOU
0
2
4
6
8
10
12
14
190
5
191
0
191
5
192
0
192
5
193
0
193
5
194
0
194
5
195
0
195
5
196
0
196
5
197
0
197
5
198
0
198
5
199
0
199
5
TREE RING YEARS
PP
M
BT/Cr
SB/Cr
MANGANESE
0
10
20
30
40
50
60
0-10 10--20 20-30 40-50 50-60 80-90 100-110 120-130 130-140 140-150 150-160
BAYOU STATIONS
PP
M
Mean level of Mn is 20.2 at Stations 0-60 and 29.1 at Stations 80-160.
Manganese
0
10
20
30
40
50
60
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000
Tree Ring Years
PP
M
Bayou Trepagnier
Stinking Bayou
IRON
0
200
400
600
800
1000
1200
1400
16000-1
0
10--
20
20-3
0
40-5
0
50-6
0
80-9
0
100
-110
120
-130
130
-140
140
-150
150
-160
BAYOU STATIONS
pp
m
Mean level of Fe is 674 at Stations 0-60 and 652 at Stations 80-160.
IRON CONCENTRATION IN BALDCYPRESS FROM BAYOU TREPAGNIER AND STINKING BAYOU
0
200
400
600
800
1000
1200
1400
1600
1800
2000191
0
191
5
192
0
192
5
193
0
193
5
194
0
194
5
195
0
195
5
196
0
196
5
197
0
197
5
198
0
198
5
199
0
199
5
TREE RING YEARS
PP
M
SB/Fe
BT/Fe
Conclusions
• Metal mobility and availability are different in wetland soils.
• Sulfate in the brackish water is reduced to sulfide and reacts with metals to form precipitates.
• The sediments are highly polluted but precipitates are stable as long as reducing conditions are maintained.
• Fe and Mn are more soluble and available to plants in the reduced state. This may account for their higher concentration in the tree rings.
Conclusions
• Waterlogged soil, circumneutral to basic pH, and acid volatile sulfides from brackish lake water are the cause of relatively low levels of metals in tree rings in spite of heavily polluted soil.
• Recently the levels of all metals in Stinking Bayou and levels of Cr, Mg and Fe in Bayou Trepagnier, likely due to urbanization.