Document n9q9Qv4G50wjbQdK42qX6mV9a

PLAINTIFF'S EXHIBIT Reprinted from ADVANCES IN X-RAY ANALYSIS, VOL. 18 Edited by W L Pickles, C S Garrett, J B Newkirk, and C 0 Ruud Book available from Plenum Publishing Corporation 227 West 17th Street, New York, New York 10011 b? OY OOO SEMI-QUANTITATIVE DETERMINATION OF ASBESTIFORM AMPHIBOLE MINERAL CONCENTRATIONS IN WESTERN LAKE SUPERIOR WATER SAMPLES P. M. Cook National Water Quality Laboratory, U. S. EPA Duluth, Minnesota 55804 ABSTRACT The amphibole mineral, cummingtonite-grunerite, has been used as a tracer for taconite tailings discharged into Western Lake Superior. The discovery of many asbestiform amphibole fibers in the tailings and Western Lake Superior water lead to concern over fiber concentrations in municipal water supplies using this water. This concern was based on the association between human asbestos exposure and increased rates of cancer of the gastrointestinal tract and peritoneum. An x-ray diffraction external standard tech nique has been developed for rapid, inexpensive, semi-quantitative determinations of amphibole mass concentration in water. The av erage amphibole mass concentrations for different Western Lake Superior water intakes compare very well with the average electron microscope fiber counts for the same samples. Daily amphibole analysis of the Duluth water supply indicates an average amphibole concentration of 0.19 milligrams per liter. ^ --I O INTRODUCTION O y* For several years x-ray diffractometry has been the key an- 4T" alytical technique for National Water Ouality Laboratory studies of -- the distribution and fate of taconite tailings which have been CJ1 discharged into Western Lake Superior at Silver Bay, Minnesota 00 since 1956. A major component of this 67,000 ton per day discharge, the amphibole mineral cummingtonite-grunerite, provides an ideal tracer for the tailings. The cummingtonite-grunerite (310) peak at 29.1 29 for copper radiation (d =* 3. 07 2l) is not found in x-ray diffraction patterns for natural lake sediments or suspended 557 P. M. Cook r.r.9 solids. X-ray diffraction patterns (Figure 1) of lake water sus pended solids which contain taconite tailings and sediment from successive 25 mm sections of the lake bottom in an area of tailings deposition show a clear gradation from large amounts of curamingtonite-grunerite (shaded peaks) in very recent surficial sediments to no curamingtonite-grunerite and little amphibole in the older, underlying sediments (75-100 mm). X-ray diffraction study of hundreds of river suspended sediment samples also indicates no detectable cummingtonite-grunerite (<1%) and only 1-2% amphibole in the natural sediments entering Western Lake Superior. Much or all of the trace amphibole is the common, non-asbestiform mineral horn blende . Further indication of the recent addition of cummingtonitegrunerite to Western Lake Superior water is provided by x-ray dif fraction patterns of many suspended sediment samples saved from the years 1940, 1950, and 1964 (Figure 2). All samples from 1940 and 1950 did not contain detectable amounts of curamingtonite-grunerite and little if any other amphibole minerals as indicated by a (110) peak at 10.6 29 (d = 8.34 A). All of the 1964 samples, however, contained large concentrations of cummingtonite-grunerite as shown by the appearance of large (110) and (310) peaks. The (110)/(310) peak ratios for these samples are typical of those found for tac onite tailings samples. 091 VlOOlS FIGURE 2----- X-RAY DIFFRACTION PATTERNS FOR SUSPENDED SOLID SAMPLES OBTAINED FROM THE DULUTH MUNICIPAL WATER SUPPLY INTAKE: A HISTORI CAL RECORD OF AMPHIBOLE CONCENTRATIONS IN DULUTH'S DRINKING WATER P. M. Cook 561 STO 044 i 62 FIGURE 3----- ELECTRON MICROGRAPH OF <2y TACONITE TAILINGS, a) LOW MAGNIFICATION (2.500X). b) HIGHER MAGNIFICATION (12.500X) VIEW OF AN AMPHIBOLE FIBER BUNDLE causes the (110) reflection and, to a lesser extent, the (310) reflection intensities to be enhanced, permitting the detection of trace amounts of amphibole. As little as 0.05 mg of <2p cummingtonite-grunerite produces measurable (110) and (310) peaks. A semi-quantitative measurement of the amphibole concentration is made by an external standard technique. This technique has been P. M. Cook 563 intensity of filter background in the x-ray diffraction pattern with increasing sample weight to 10 mg; and the linearity of a plot of quartz peak (d = 3.33 X) intensity versus weight of quartz, regard less of total sample weight in the range 0-12 mg. AMPHIBOLE (110) PEAK X-RAY INTENSITY counts/second S T 0 0 4 4 164 FIGURE 4-----EXTERNAL STANDARD CURVE FOR AMPHIBOLE SEMI-QUANTITATIVE ANALYSIS The non-linearity of the external standard curve (Figure 4) is due to a decreasing degree of preferred orientation as the amount of amphibole increases. This is indicated by decreasing araphibole (110)/(31Q) and amphibole (110)/quartz peak ratios with increasing weight of the standard amphibole-quartz mixture on the filter. The utility of the external standard curve depends on how well the curve models araphibole preferred orientation in environmental samples. Similar curves based on samples prepared with increased amounts of natural sediment agreed well with the standard curve used. With large amounts of natural sediment, the amphibole peak intensity is weakened which would cause an underestimation of amphibole concen trations. Other standard curves were employed to estimate the amphibole concentration in the few samples with a very high concentration of non-amphibole minerals. P. M. Cook 06.*5 C a u QP r-1 O Z cP o u 0 CO o co IT O 10 O ^ jn)0j*dUJ9) J 910M 91(01 . u >u > UZZZ>tfi/)</> pui* UJ 3 joi) ojidosjd I /Buj spuds ppudsns at> zui aus: o3 < CJ H tO U- > "> <*| -I < OCs-O3 HZ--I 0> cg3 a uj wa: QZUJ H< & to c > a 3z to <J I< H a < < 1oMwC-D1 a <Oj--PI c =: o U O u a 2 E- >- < u uV. <-- MK-J QV iTIIv =MH3 c a UJ 3DP UOPJ OH hU-^4 <3 oo --I- CD O 4T~ 4T" <T> cn P. M. Cook 567 ACKNOWLEDGEMENTS The author wishes to gratefully acknowledge the assistance of Mr. James Tucker of the National Water Quality Laboratory for electron microscope examinations of water and tailings samples; Mr. Robert Fulton and Mr. David Marklund for their excellent work in preparing many of the samples examined by x-ray diffraction; and Dr. Billy Fairless of the Environmental Protection Agency, Region V, Central Regional Laboratory, for providing water intake fiber counts. REFERENCES 1. I. J. Selikoff, E. C. Hammond and J. Churg, "Carcinogenicity of Amosite Asbestos," Arch. Environ. Health _25, 183-186 (1972). 2. J. G. Eaton and G. E. Likens, "Use of Membrane Filters in Gravimetric Analyses of Particulate Matter in Natural Waters," Water Resources Res. _5, 1151-1156 (1969). 3. A. L. Rickards, "Estimation of Trace Amounts of Chrysotile Asbestos by X-Ray Diffraction," Anal. Chem. 44_, 1872-1873 (1972) . 4. J. V. Crable, "Quantitative Determination of Chrysotile, Amosite, and Crocidolite by X-Ray Diffraction," Am. Ind. Hyg. Assoc. J. 27, 293-298 (1966). 5. C. E. Adams, "Summer Circulation m Western Lake Superior," Proc. 13th Conf. on Great Lakes Res., 862-879 (1970). STOOkU I 68