The Effects of Smelter Emissions on the Terrestrial ... · Flin Flon smelter-derived metals, about...
1
103 00'W 55 15'N 54 00'N 55 15'N 54 00'N 99 00'W 103 00'W 99 00'W Snow Lake Flin Flon A B SASKATCHEWAN MANITOBA 20 300 540 1100 3600 100000 0 50 75 90 98 100 ppb percentile BEDROCK LEGEND PALEOZOIC Precambrian Shield Mercury Carbonate rocks Intrusive rocks Metasediments Metavolcanics MIN. MAX. %TILE #SAMP (ppb) (ppb) 3 65 70.4 1107 65 90 84.3 219 90 140 94.9 166 140 220 98.3 54 220 400 99.6 21 400 2800 100 6 103 00'W 55 15'N 54 00'N 55 15'N 54 00'N 99 00'W 103 00'W 99 00'W SASKATCHEWAN MANITOBA SASKATCHEWAN MANITOBA Snow Lake Flin Flon 1 10 100 1000 10000 100000 1000000 Hg (ppb) NNW SSW 1 1 10 10 100 100 Distance from smelter (km) Humus Till Humus Till M o b i l e N o n - m o b i l e N o n - m o b i l e M o b i l e In C-horizon till, concentrations of all smelter-related elements are commonly lower than in humus and show no direct relationship to distance from the smelter (see dot map and graph). At depths greater than 40 centimetres, trace metal distribution is related primarily to bedrock composition, modified by the effects of glacial erosion, transport, and deposition. The dot map displays concentrations of mercury in till superimposed on bedrock geology. Till derived from carbonate rock (blue on geology map) contains lower trace metal concentrations than till derived from Shield terrain. High concentrations of mercury in till in the Flin Flon and Snow Lake areas are related to naturally occurring mercury in bedrock. In both humus and till, trace metals are either "mobile" and readily available for uptake by plants and other organisms, or "non-mobile" and unavailable. Mercury is retained primarily in immobile phases in both humus and till (see pie charts on graph). Humus collected in areas of high contamination (>100,000 ppb) adjacent to the smelter contains significant concentrations (41% of the total) of mercury in "mobile" forms which may represent an environmental hazard. Elevated concentrations of mercury in the underlying till suggest downward leaching, although enrichment could also reflect natural values associated with known ore bodies in the Flin Flon area. At distances greater than 85 kilometres from the smelter, mercury concentrations approach regional background in humus, and less mercury (30% of the total) is "mobile". In humus, concentrations of smelter related elements decrease with distance from the smelter stack, describing a "bull's eye" pattern up to 85 km wide. The shape of the bull's eye is slightly distorted in the directions of prevailing winds. Adjacent to the smelter stack, mercury concentrations are up to 500 times greater than background levels (see concentration/distribution graph below). The map at the left depicts the bull's eye distribution for mercury, and it is similar to the patterns for other smelter-emitted elements. Near the smelter, heavy metals are largely retained in smelter-derived particulates (as shown in the grain images below), and with distance, the number and size of these particles decrease, and/or the composition varies. This suggests that particulate emissions are subject to density sorting by wind. The distributions of trace metals unrelated to smelter emissions (e.g. nickel, cobalt, chromium) do not exhibit the bull's eye pattern. Trace metals in surficial deposits reflect bedrock geology and the composition of glacially transported material. In some areas they can also reflect the effects of mining and smelting activities. Since the early 1930's, smelting of base metal ore at Flin Flon, Manitoba, has released large quantities of metal-rich particulates into the atmosphere. The metals include arsenic, cadmium, copper, iron, mercury, lead, and zinc, all of which can affect human health, wildlife, and vegetation. To determine the dispersal and fate of Flin Flon smelter-derived metals, about 2000 samples of humus (decomposed leaf and plant litter) and the underlying C-horizon (till) were collected over a 36,000 km 2 area and analyzed geochemically. Trace Metals in Till Mobility of Metals Trace Metals in Humus Sample site M o b i l e N o n - m o b i l e Hg-rich grain in humus 10 μm diameter Glass grain in humus 25 μm diameter M o b i l e N o n - m o b i l e A B (see humus map for transect location) Mercury (ppb) A B Transect The Effects of Smelter Emissions on the Terrestrial Environment Frequency = Arrow Length Speed = Arrow Width SW W NW N NE E SE S Wind Rose
Transcript of The Effects of Smelter Emissions on the Terrestrial ... · Flin Flon smelter-derived metals, about...
103 00'W
55 1
5'N
54 0
0'N
55 15'N54 00'N
99 00'W
103 00'W 99 00'W
Snow Lake
Flin Flon
A
B
SASKATCHEWAN MANITOBA
20 300 540 1100 3600 100000
0 50 75 90 98 100
ppb
percentile
BEDROCK LEGEND
PALEOZOIC
Precambrian Shield
Mercury
Carbonate rocks
Intrusive rocks
Metasediments
Metavolcanics
MIN. MAX. %TILE #SAMP(ppb) (ppb)
3 65 70.4 110765 90 84.3 21990 140 94.9 166
140 220 98.3 54220 400 99.6 21400 2800 100 6
103 00'W
55 1
5'N
54 0
0'N
55 15'N54 00'N
99 00'W
103 00'W 99 00'WSASKATCHEWAN MANITOBA
SASK
ATC
HEW
AN
MA
NIT
OB
A
Snow Lake
Flin Flon
1
10
100
1000
10000
100000
1000000
Hg
(ppb
)
NNW SSW
11 1010100 100
Distance from smelter (km)
Humus
Till
Humus
Till
MobileNo
n-m obile
No
n-m obile
Mobile
In C-horizon till, concentrations of all smelter-related elements are commonly lower than in humus and show no direct relationship to distance from the smelter (see dot map and graph). At depths greater than 40 centimetres, trace metal distribution is related primarily to bedrock composition, modified by the effects of glacial erosion, transport, and deposition. The dot map displays concentrations of mercury in till superimposed on bedrock geology. Till derived from carbonate rock (blue on geology map) contains lower trace metal concentrations than till derived from Shield terrain. High concentrations of mercury in till in the Flin Flon and Snow Lake areas are related to naturally occurring mercury in bedrock.
In both humus and till, trace metals are either "mobile" and readily available for uptake by plants and other organisms, or "non-mobile" and unavailable. Mercury is retained primarily in immobile phases in both humus and till (see pie charts on graph). Humus collected in areas of high contamination (>100,000 ppb) adjacent to the smelter contains significant concentrations (41% of the total) of mercury in "mobile" forms which may represent an environmental hazard. Elevated concentrations of mercury in the underlying till suggest downward leaching, although enrichment could also reflect natural values associated with known ore bodies in the Flin Flon area. At distances greater than 85 kilometres from the smelter, mercury concentrations approach regional background in humus, and less mercury (30% of the total) is "mobile".
In humus, concentrations of smelter related elements decrease with distance from the smelter stack, describing a "bull's eye" pattern up to 85 km wide. The shape of the bull's eye is slightly distorted in the directions of prevailing winds. Adjacent to the smelter stack, mercury concentrations are up to 500 times greater than background levels (see concentration/distribution graph below). The map at the left depicts the bull's eye distribution for mercury, and it is similar to the patterns for other smelter-emitted elements. Near the smelter, heavy metals are largely retained in smelter-derived particulates (as shown in the grain images below), and with distance, the number and size of these particles decrease, and/or the composition varies. This suggests that particulate emissions are subject to density sorting by wind. The distributions of trace metals unrelated to smelter emissions (e.g. nickel, cobalt, chromium) do not exhibit the bull's eye pattern.
Trace metals in surficial deposits reflect bedrock geology and the composition of glacially transported material. In some areas they can also reflect the effects of mining and smelting activities. Since the early 1930's, smelting of base metal ore at Flin Flon, Manitoba, has released large quantities of metal-rich particulates into the atmosphere. The metals include arsenic, cadmium, copper, iron, mercury, lead, and zinc, all of which can affect human health, wildlife, and vegetation. To determine the dispersal and fate of Flin Flon smelter-derived metals, about 2000 samples of humus (decomposed leaf and plant litter) and the underlying C-horizon (till) were collected over a 36,000 km2 area and analyzed geochemically.
Trace Metals in Till
Mobility of Metals
Trace Metals in Humus
Sample site
Mobile
Non-m
obile
Hg-rich grain in humus
10 m m diameter
Glass grain in humus
25 m m diameter
Mobile
Non-m
obile
A B(see humus map for transect location)
Mercury (ppb)
A B Transect
The Effects of Smelter Emissions on the Terrestrial Environment
Frequency = Arrow LengthSpeed = Arrow Width
SW
W
NWN
NE
E
SES
Wind Rose
