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Asbestos pollution assessment in river water by PIXE methods
Nuclear Instruments and Methods 181 (1981) 239-241 © North-Holland Publishing Company
ASBESTOS POLLUTION ASSESSMENT IN RIVER WATER BY PIXE METHODS S. MONARO, R. LECOMTE, P. PARADIS, S. LANDSBERGER Laboratoire de Physique Nucldaire, Universitd de Montrdal, Qudbec, Canada
and G. DESAULNIERS Ddpartement de Mddecine du Travail et d'Hygi~ne du Milieu, Facultd de Mddecine. UniversitO de MontrOal, Qudbec, Canada
Asbestos pollution levels in river water are assessed by PIXE measurements. The application of the PIXE process in the evaluation of asbestos pollution in river water is compared with the standard measuring technique which uses an electron microscope. The data suggest that PIXE may be advantageously employed due to its simplicity of operation and analysis.
1. Introduction
lacks precision, it is tedious and expensive. Clearly, it would be interesting to devise new methods to study and follow up the asbestos pollution levels in water. It is the purpose of the present work to show how PIXE techniques can be advantageously used for a qualitative and quantitative evaluation of asbestos contamination in water.
A pollutant that has attracted special attention in recent years in asbestos. It is well known that asbestos fibers are common in the environment. In fact, all persons in urban areas are exposed to asbestos in air from the wearing down of automobile brake linings and from the practise of spraying it (for insulating purpose) in the construction of new buildings [1,2]. Recent studies in the United States and Canada have shown that asbestos is also a common constituent in much of the drinking water [ 2 - 4 ] . Furthermore, environmental exposure to asbestos is increased by filtration of beverages and pharmaceuticals through asbestos filters [5,6]. The harmful effects from asbestos pollution in air have been known and investigated for years and there is no doubt about the dangers related to breathing asbestos fibers [1,7]. The evidence, however, is not so one-sided in the case of asbestos fiber ingestion since the few existing studies give contradictory results [3]. Perhaps this uncertainty is caused by the large interval of time (as long as 2 0 - 3 0 years) between the initial exposure and the appearance of biological effects in the affected subjects. Another cause could be the lack of systematic data over the same period of years. Such data are indeed essential if one wants to gauge the long-range impact of asbestos pollution in water upon the population. The identification of asbestos fibers in water is usually carried out through transmission electron microscope (TEM) measurements [3,8]. This method
2. Experimental procedures Water samples have been collected from the Bdcancour river in Qurbec. This river drains the water from the mining areas of Thetford Mines and Black Lake and it is highly exposed to the runoff waters coming from mining wastes and taihngs located on the river's edges. The samples were collected from the locations placed upstream and downstream from the tailing dumps in order to compare data from exposed and unexposed pollution sites. The total distance covered was approximately 180 km. From each of the 5000 ml collected samples, two volumes of 250 ml were simultaneously filtered through GS-type Millipore filters. The various pairs of Filters with their retained residues were then dried and prepared for the TEM and PIXE measurements, respectively, in order to compare the results obtained by the TEM method with those extracted by PIXE techniques. The filter prepared for the PIXE measurements was placed whole in a beaker and ashed at low temperature to destroy both the organic matrix of the 239
IX. ANALYSIS OF WATER
240
S. Monaro et al. / A s b e s t o s pollution assessment
sample and of the filter. The ashes were then dissolved in 1 ml of HNO3(2N) and doped with 500 ppm (or 2000) of Zn used as internal standard. The targets were prepared by placing 20 #1 of this solution on a 0.1 #m Nucleopore filter and drying under vacuum. The targets were bombarded with 1.6 MeV proton beam obtained from the Universit6 de Montr6al Van de Graaff accelerator. The sample X-ray yields (asbestos and its non-fibrous counterpart serpentine, are composed essentially of silicon and magnesium as 3 M g O . 2 S i O 2 . 2 H 2 0 , plus a few heavier trace elements) were measured with the targets at 45 ° to the incident beam and by a Si(Li) detector having 160 eV resolution at 5.9 keV. The X-ray spectra were automatically recorded and analysed on-line by a 3100 CDC computer using methods and techniques developed in this laboratory [9,10].
50
20
~'~
f
I0
0
(o)
r'- X 1/10
Si
Mg l
X
Zrl
Fe
No !A~
J t,i Z
z
0
Si
-tO ,"r" bJ ira
30 K
03 I,--
z
(b)
- X 1/10
20
0 (.3
A~
[
3. Results I0
Two typical X-ray spectra are shown in fig. 1. The spectrum above is obtained from water collected upstream the mining area whereas the spectrum below is from water taken close to the mining waste area. A qualitative comparison of the two spectra already shows an increase of Mg, Si and other trace elements in the second sample. The experimental results for the elemental concentrations are summar-
Fe
Mgji
I~
!Ca
i
o
\
Z~~
J4/ 200
,
400
600
;"
CHANNEL NUMBER Fig. 1. (a) X-ray spectrum obtained from water collected upstream the mining area (unpolluted site). (b) X-ray spectrum obtained from water collected close to the mining waste area (polluted site).
MAGNESIUM
0.2
Table 1 Results from PIXE and TEM measurements on the water samples collected in the B6cancour river and described in the text. Elements
Concentrations (mg/1) Upstream
Downstream
Na Mg AI Si S C1 K Ca Ti Mn Fe Zn (Int. standard)
2.137 0.146 0.199 0.621 0.0042 0.0138 0.0164 0.0076 0.0036 0.0169 0.191 2.000
0.494 0.539 1.229 2.840 0.0051 0.0119 0.1084 0.0310 0.0260 0.1240 1.020 2.000
Fiber/liter ~l
2.3 X 108
2.8 X 109
o oi SILICON
r~ I=7
"-'" °.° MINFNG AREA
uJ 2.0
o Z
•
TOWNS
•
LAKES
1.0
0.0 I
I
I
I
I
I
I
25
50
75
I00
125
150
175
DISTANCE (kin)
Fig. 2. Mg and Si concentration values determined along the B~cancour river. The solid points on the curves give the approximate position of the sampling sites (1) Thetford Mines, (2) Black Lake, (3) Lake ~ la Truite, (4) Lake William, and (5) Lake Joseph.
S. Monaro et al. / Asbestos pollution assessment ized in table 1 where the number of asbestos fibers (f/l), obtained b y TEM measurements from the counterparts o f the two samples analyzed with PIXE (see above), are also included for comparison [11]. Clearly the water collected close to the tailing dumps (downstream) shows a higher level of pollution both from PIXE and TEM measurements. An analysis o f the samples collected from the ten chosen sites yields the Mg and Si concentration shown graphically in fig. 2. It is evident that the Mg and Si concentration increases greatly right after the mining area, it is low upstream and decreases sharply after the lakes located downstream. This decrease in concentration o f Mg and Si could suggest the presence o f a sedimentation process o f the suspended matter.
4. C o n d u f i o n It seems clear from the present study that PIXE is a suitable technique for qualitative and quantitative asbestos pollution assessments in (river) water. The PIXE method has the only disadvantage that it does not yield the number o f a s b e s t o s f / l and their dimension. These data, which are determined only through TEM methodology, are o f paramount significance since it is very probable that some health hazards
241
depend on the number and size of the ingested fibers. However, even in this case PIXE is useful since by PIXE the asbestos pollution levels in river water can be obtained quickly and reliably and then the sites of particular importance may be surveyed by the TEM technique.
References [1] L. Hodges, Environmental pollution (eds. Holt, Rinehart and Winston; 1973). [2] Chem. Eng. News, 51 (1973) 18. [3] L.M. McMillan, R.G. Stout and B.F. Willey, Envir. Sci. Tech. 2 (1977) 390. [4] R.P. Schmidt, D.C. Lindsten and T.F. Shannon, Envir. Sci. Tech. 2 (1977) 462. [5] R.W. Durham and T. Pang, CIC-CCIW Syrup. on Water quality parameters, Burlington, Ont. Canada (1973). [6] G.H. Kay, J. Am. Water Works Assoc. 66 (1974) 9. [7] I.J. Selikoff, Environment 11 (1969) 2. [8] E. Chatfield, R.W. Glass and J. Dillow, EPA-600/4-78011, U.S. Environmental Protection Agency, Athens, Georgia, 30601 (1978). [9] M. Barrette, G. Lamoureux, E. Lebel, R. Lecomte, P. Paradis and S. Monaro, Nucl. Instr. and Meth. 134 (1976) 189. [10] R. Lecomte, P. Paradis, S. Monaro, M. Barrette, G. Lamoureux and H.A. Menard, Nucl. Instr. and Meth. 150 (1978) 289. [111 G. Desaulniers, A. P'an, M. Trudeau, R. Lecomte, S. Landsberger, P. Paradis and S. Monaro, to be published.
IX. ANALYSIS OF WATER
ASBESTOS POLLUTION ASSESSMENT IN RIVER WATER BY PIXE METHODS S. MONARO, R. LECOMTE, P. PARADIS, S. LANDSBERGER Laboratoire de Physique Nucldaire, Universitd de Montrdal, Qudbec, Canada
and G. DESAULNIERS Ddpartement de Mddecine du Travail et d'Hygi~ne du Milieu, Facultd de Mddecine. UniversitO de MontrOal, Qudbec, Canada
Asbestos pollution levels in river water are assessed by PIXE measurements. The application of the PIXE process in the evaluation of asbestos pollution in river water is compared with the standard measuring technique which uses an electron microscope. The data suggest that PIXE may be advantageously employed due to its simplicity of operation and analysis.
1. Introduction
lacks precision, it is tedious and expensive. Clearly, it would be interesting to devise new methods to study and follow up the asbestos pollution levels in water. It is the purpose of the present work to show how PIXE techniques can be advantageously used for a qualitative and quantitative evaluation of asbestos contamination in water.
A pollutant that has attracted special attention in recent years in asbestos. It is well known that asbestos fibers are common in the environment. In fact, all persons in urban areas are exposed to asbestos in air from the wearing down of automobile brake linings and from the practise of spraying it (for insulating purpose) in the construction of new buildings [1,2]. Recent studies in the United States and Canada have shown that asbestos is also a common constituent in much of the drinking water [ 2 - 4 ] . Furthermore, environmental exposure to asbestos is increased by filtration of beverages and pharmaceuticals through asbestos filters [5,6]. The harmful effects from asbestos pollution in air have been known and investigated for years and there is no doubt about the dangers related to breathing asbestos fibers [1,7]. The evidence, however, is not so one-sided in the case of asbestos fiber ingestion since the few existing studies give contradictory results [3]. Perhaps this uncertainty is caused by the large interval of time (as long as 2 0 - 3 0 years) between the initial exposure and the appearance of biological effects in the affected subjects. Another cause could be the lack of systematic data over the same period of years. Such data are indeed essential if one wants to gauge the long-range impact of asbestos pollution in water upon the population. The identification of asbestos fibers in water is usually carried out through transmission electron microscope (TEM) measurements [3,8]. This method
2. Experimental procedures Water samples have been collected from the Bdcancour river in Qurbec. This river drains the water from the mining areas of Thetford Mines and Black Lake and it is highly exposed to the runoff waters coming from mining wastes and taihngs located on the river's edges. The samples were collected from the locations placed upstream and downstream from the tailing dumps in order to compare data from exposed and unexposed pollution sites. The total distance covered was approximately 180 km. From each of the 5000 ml collected samples, two volumes of 250 ml were simultaneously filtered through GS-type Millipore filters. The various pairs of Filters with their retained residues were then dried and prepared for the TEM and PIXE measurements, respectively, in order to compare the results obtained by the TEM method with those extracted by PIXE techniques. The filter prepared for the PIXE measurements was placed whole in a beaker and ashed at low temperature to destroy both the organic matrix of the 239
IX. ANALYSIS OF WATER
240
S. Monaro et al. / A s b e s t o s pollution assessment
sample and of the filter. The ashes were then dissolved in 1 ml of HNO3(2N) and doped with 500 ppm (or 2000) of Zn used as internal standard. The targets were prepared by placing 20 #1 of this solution on a 0.1 #m Nucleopore filter and drying under vacuum. The targets were bombarded with 1.6 MeV proton beam obtained from the Universit6 de Montr6al Van de Graaff accelerator. The sample X-ray yields (asbestos and its non-fibrous counterpart serpentine, are composed essentially of silicon and magnesium as 3 M g O . 2 S i O 2 . 2 H 2 0 , plus a few heavier trace elements) were measured with the targets at 45 ° to the incident beam and by a Si(Li) detector having 160 eV resolution at 5.9 keV. The X-ray spectra were automatically recorded and analysed on-line by a 3100 CDC computer using methods and techniques developed in this laboratory [9,10].
50
20
~'~
f
I0
0
(o)
r'- X 1/10
Si
Mg l
X
Zrl
Fe
No !A~
J t,i Z
z
0
Si
-tO ,"r" bJ ira
30 K
03 I,--
z
(b)
- X 1/10
20
0 (.3
A~
[
3. Results I0
Two typical X-ray spectra are shown in fig. 1. The spectrum above is obtained from water collected upstream the mining area whereas the spectrum below is from water taken close to the mining waste area. A qualitative comparison of the two spectra already shows an increase of Mg, Si and other trace elements in the second sample. The experimental results for the elemental concentrations are summar-
Fe
Mgji
I~
!Ca
i
o
\
Z~~
J4/ 200
,
400
600
;"
CHANNEL NUMBER Fig. 1. (a) X-ray spectrum obtained from water collected upstream the mining area (unpolluted site). (b) X-ray spectrum obtained from water collected close to the mining waste area (polluted site).
MAGNESIUM
0.2
Table 1 Results from PIXE and TEM measurements on the water samples collected in the B6cancour river and described in the text. Elements
Concentrations (mg/1) Upstream
Downstream
Na Mg AI Si S C1 K Ca Ti Mn Fe Zn (Int. standard)
2.137 0.146 0.199 0.621 0.0042 0.0138 0.0164 0.0076 0.0036 0.0169 0.191 2.000
0.494 0.539 1.229 2.840 0.0051 0.0119 0.1084 0.0310 0.0260 0.1240 1.020 2.000
Fiber/liter ~l
2.3 X 108
2.8 X 109
o oi SILICON
r~ I=7
"-'" °.° MINFNG AREA
uJ 2.0
o Z
•
TOWNS
•
LAKES
1.0
0.0 I
I
I
I
I
I
I
25
50
75
I00
125
150
175
DISTANCE (kin)
Fig. 2. Mg and Si concentration values determined along the B~cancour river. The solid points on the curves give the approximate position of the sampling sites (1) Thetford Mines, (2) Black Lake, (3) Lake ~ la Truite, (4) Lake William, and (5) Lake Joseph.
S. Monaro et al. / Asbestos pollution assessment ized in table 1 where the number of asbestos fibers (f/l), obtained b y TEM measurements from the counterparts o f the two samples analyzed with PIXE (see above), are also included for comparison [11]. Clearly the water collected close to the tailing dumps (downstream) shows a higher level of pollution both from PIXE and TEM measurements. An analysis o f the samples collected from the ten chosen sites yields the Mg and Si concentration shown graphically in fig. 2. It is evident that the Mg and Si concentration increases greatly right after the mining area, it is low upstream and decreases sharply after the lakes located downstream. This decrease in concentration o f Mg and Si could suggest the presence o f a sedimentation process o f the suspended matter.
4. C o n d u f i o n It seems clear from the present study that PIXE is a suitable technique for qualitative and quantitative asbestos pollution assessments in (river) water. The PIXE method has the only disadvantage that it does not yield the number o f a s b e s t o s f / l and their dimension. These data, which are determined only through TEM methodology, are o f paramount significance since it is very probable that some health hazards
241
depend on the number and size of the ingested fibers. However, even in this case PIXE is useful since by PIXE the asbestos pollution levels in river water can be obtained quickly and reliably and then the sites of particular importance may be surveyed by the TEM technique.
References [1] L. Hodges, Environmental pollution (eds. Holt, Rinehart and Winston; 1973). [2] Chem. Eng. News, 51 (1973) 18. [3] L.M. McMillan, R.G. Stout and B.F. Willey, Envir. Sci. Tech. 2 (1977) 390. [4] R.P. Schmidt, D.C. Lindsten and T.F. Shannon, Envir. Sci. Tech. 2 (1977) 462. [5] R.W. Durham and T. Pang, CIC-CCIW Syrup. on Water quality parameters, Burlington, Ont. Canada (1973). [6] G.H. Kay, J. Am. Water Works Assoc. 66 (1974) 9. [7] I.J. Selikoff, Environment 11 (1969) 2. [8] E. Chatfield, R.W. Glass and J. Dillow, EPA-600/4-78011, U.S. Environmental Protection Agency, Athens, Georgia, 30601 (1978). [9] M. Barrette, G. Lamoureux, E. Lebel, R. Lecomte, P. Paradis and S. Monaro, Nucl. Instr. and Meth. 134 (1976) 189. [10] R. Lecomte, P. Paradis, S. Monaro, M. Barrette, G. Lamoureux and H.A. Menard, Nucl. Instr. and Meth. 150 (1978) 289. [111 G. Desaulniers, A. P'an, M. Trudeau, R. Lecomte, S. Landsberger, P. Paradis and S. Monaro, to be published.
IX. ANALYSIS OF WATER