The degree of Cu contamination would depend on several factors: type of hi vol sampler used, use of a shelter in sample collection, and meteorological conditions at the sampling site (e.g., stagnant air could cause higher copper contamination). Gelman Hurricane samplers have also been tested to determine the possibility of sample contamination for the following elements: Fe, Cr, Pb, Mn, Co, Zn, V, Al, Ni, Na, Mg, Ca, K, and Sr. This study was performed by a combination of neutron activation analysis and atomic absorption analysis. No sample contamination by the Gelman Hurricane samplers was found for the elements above. A c know ledginen t We wish to acknowledge the ESSA Research Laboratories of Boulder, Colo., and the U S . Air Force, Hickam Field, Honolulu, Hawaii, for facilitating our work through the loan of a portable observation tower and access to a coastal installation site, respectively. Neutron activation analyses were performed at the Rhode Island Nuclear Science Center, Narragansett, R.I.
Literature Cited Ludwig, J. A., Morgan, G. B., McMullen, T. B., EOS, Trans. Ainer. Geophys. Union 51, 468-475 (1970). Mason, B., “Principles of Geochemistry,” Wiley, New York, N.Y., 1960, p 44. U.S. Public Health Service, “Air Pollution Measurements of the National Air Sampling Network, 1953-57,” PHS.Publ. no. 637, Washington, D.C., 1958. U S . Public Health Service, “Air Pollution Measurements of the National Air Sampling Network, 1957-61,” PHS Publ. no. 978, Washington, D.C., 1962. U S . Public Health Service, “Air Pollution Measurements of the National Air Sampling Network, 1963,” PHS Washington, D.C., 1965. U S . Public Health Service, “Air Pollution Measurements of the National Air Sampling Network, 1966,” PHS, Washington, D.C., 1967. U S . Public Health Service, “Air Quality Data,” 1966 ed., PHS Publ. no. APTD 68-9, Washington, D.C., 1968. Receiced for reciew Jan. 25, 1971. Accepted March 19, 1971. This work was suuuorted in imior uart b y the Encironnzental Protection Agenci; Air Pollution Contra Ofice under grant ROI-AP 00617.
Method for the Storage of Samples for Dissolved Gas Analyses W. C. Weimer and G . Fred Lee1 Water Chemistry Program, University of Wisconsin, Madison, Wis. 53706
A bottle for the storage of water samples prior to analysis for dissolved gas concentrations has been designed t o eliminate contact between the sample and the atmosphere. Analyses of water samples for dissolved nitrogen and methane content indicated that the concentrations of these gases remained unchanged during a two-day storage period and that the samples could, potentially, be stored for longer time periods. Precision of the overall sampling and analytical technique was =k5-7%;.
M
any analyses of dissolved gas concentrations in water samples have been reported since Swinnerton et al. (1962a,b) published their initial work in this area involving the use of a Fisher Model 25 gas partitioner. However, few reports describe the methods of sample collection and storage preceding the actual analysis. Early in the investigation of the dissolved gas content of Lake Mary water (Weimer, 1970), it was found that the method of sample collection and storage greatly affected the reproducibility of dissolved methane concentration measurements. Samples stored in 250-ml, glassstoppered reagent bottles gave variable results. Generally, succeeding analyses from the same sample bottle indicated decreasing amounts of methane. Because of the poor reproducibility obtained with this storage method, a dissolved gas sampling bottle was designed to eliminate contact of the water sample with the atmosphere after the initial sample collection was completed. Exper iinen tal Analyses for nitrogen and methane dissolved in water samples were performed with a Fisher Model 25 gas parTo whom correspondence should be addressed. 1136 Environmental Science & Technology
titioner and a modification of the analytical procedure employed by Swinnerton et al. (1962a,b). This analytical procedure involves: (1) introduction of the water sample into a specially designed gas stripping chamber, (2) removal of the dissolved gases from the water sample by stripping with a n inert carrier gas (He was used in this study), (3) separation of the gases from each other through gas-solid chromatography, and (4) analysis of the components of the gas mixture via thermal conductivity measurements. The sample was introduced into this system from the dissolved gas sampling bottle shown in Figure 1. This bottle was designed so that the water sample in it would not be exposed to the atmosphere before completion of the dissolved gas analysis. Water from a modified Van Dorn sampler (Hydro Products, 1967) was added through the neck of the dissolved gas sampling bottle; three bottle volumes were first allowed to flush through the neck and the stopcock. The stopcock was closed, allowing water to fill completely the neck of the bottle. The plunger was inserted (about 0.5-1 in. into the neck) with the stopcock of the bottle open to expel some of the water from the exit port. The stopcock was then closed. The dissolved gas sampling bottle was fitted with a male Leur tip at the stopcock. For sample injection, this tip on the bottle was fitted into a female Leur tip (a hypodermic needle) attached to an Aerograph two-position, six-way linear valve that contained six entrance or exit portals. Two were connected to the sample loop (a ‘/*-in. 0.d. polypropylene tube that could be adjusted to hold any desired water volume), two served as inlet and outlet valves for the sample loop, and the remaining two were connected directly into the gasflow system. The valve was arranged so that the flow of the carrier gas could be directed through the valve, bypassing the sample loop, or through the sample loop and exit from the valve. This arrangement allowed a fresh sample to be placed into the sample loop after the preceding sample had
been transferred to the gas stripping chamber and the valve had been repositioned. To fill the sample loop, the Leur tip of the sampling bottle was attached to the sample loop inlet on the valve and the plunger of the sample bottle was depressed while the gas flow bypassed the loop. The valve was then repositioned so that the carrier gas forced the water sample from the sample loop into the gas stripping chamber. Results and Discussion
The dissolved gas sampling bottles were used during investigation of dissolved nitrogen and methane in Lake Mary, Vilas County, Wis. Samples collected at Lake Mary were generally packed in ice or snow and transported approximately 50 miles to the site of analysis, Kemp Biological Station, Woodruff, Wis. Analysis of the samples away from Lake Mary required that some samples would not be analyzed until up to ten hours after collection. Because of this delay, there was some chance that the dissolved gas concentrations might change (specifically, loss of methane could occur) during the time from collection until analysis. T o evaluate the effect of storage on dissolved gas measurements, some samples were analyzed approximately two to ten hours after collection and again after two days (Table I). Most samples encountered temperature variations during this time, either warming or cooling, and gas solubilities were, therefore, altered. However, most of the variations in concentrations between the two analysis times are within the ranges obtained for replicate analysis of samples from one bottle without storage between analyses (Table 11). Apparently, once the
water samples were in the gas sampling bottles, the dissolved gas concentrations remained constant at least until the time of analysis. Any changes encountered occurred during transfer of the samples from the water sampler to the dissolved gas sampling bottles. Although determination of loss or gain of dissolved gases during this transfer is impossible, these changes appeared to be minor. If these samples can be stored for two days with no apparent dissolved gas concentration changes, then it is likely that longer storage periods are also possible with this dissolved gas sampling bottle. The precision obtained in the dissolved gas analyses is indicated in Table 11. These data reflect the combined effects of various potential sources of error, including sampling of the water column, filling of the gas sampling bottles, and analysis of these samples for dissolved gases. Three casts with
P L U N G E R (from --.I BECTON, DICKINSON and CO.,RUTHERFORD NEW JERSEYI50 m l "PLASTIPAK" U'OLUME OF NECK = 60 ml.
DISPOSABLE SYRINGE
VERTICAL SCALE;
b"=I cm
HORIZONTAL S C A L E : ' 1 . . I cm
TO G A S STRIPPING CHAMBER
Table I. Effect of Storage on Dissolved Gas Concentrations.
-
Dissolved eas concn melliter
Lake Mary, depth, m
Watez temp, C
1 2 4 7 9 17
15.9 14.2 6.8 4.5 4.5 5.0
(I
9/23/67 N2 CHa
16.1 16.5 18.4 19.4 19.6 16.0
... ...
... ... 3.7 15.4
9/%/67 NP
CHY
18.2 17.1 17.0 18.7 19.6 18.5
... ...
BOTTLE VOLUME* 300ml
...
CARRIER GAS FLOW IN
... 4.1 15.5
u Figure 1. Dissolved gas sampling bottle
All concentration values are the average of three or four analyses.
Table 11. Precision of Dissolved Gas Analyses Dissolved gas concn in each sample bottle, mg/l.
Nz5
CHab
Van Dorn cast no.
Depth, m
Sample bottle no.
Meanc
Rangee
1 1 2 2 2
5 5 5 5 5 5 5 16 16 16 16 16 16 16
2 3 4 5 6 7 8 9 10 12 13 14 15 16
24.4 f 0 . 3 23.7 f 0 . 6 23.2 =t 1 . 1 22.2 f 0 . 2 22.2 f 0 . 2 22.7 f 1 . 1 22.6 f 0 . 4 22.2 =t 1 . 1 22.0 f 0 . 5 22.8 f 1 . 4 21.6 f 0 . 1 21.9 f 1 . 1 22.3 f 0 . 5 22.4 =t 0 . 3
0.6 1.3 1.8 0.4 0.4 2.2 0.5 1.8 1.1 2.6 0.2 2.2 0.9 0.7
3 3 4 4 5 5 5
6 6
Meane
Rangee
... ...
... ... ...
...
...
...
22.4 f 0 . 8 22.9 k 0 . 9 23.4 =t 0 . 3 21.9 f 0 . 6 21.0 k 1 . 0 22.4 =t 0 . 6 22.1 k 1 . 4
1.6 1.9 0.6 1.1 2.3 1.1 2.7
NZconcn at 5-m depth: 22.9 f 0.9 mg/liter; range: 3.0 mg/liter. NZconcn at 16-m depth: 22.2 f 0.8 mg/liter: range: 3.5 mg/liter. CHa concn at 16-m depth: 22.2 f 1.1 mg/liter; range: 4.1 mg/liter. The standard deviation values and the ranges are for all of the individual determinations. ~~
Volume 5, Number 11, November 1971 1137
a Van Dorn sampler were made at two depths, 5 m and 16 m. Two or three dissolved gas sampling bottles were filled with water from each of the casts with the Van Dorn sampler. The dissolved gas concentrations in each sampling bottle were determined three or four times. These data, therefore, indicate a measure of the variability encountered in analysis of one sample bottle and from taking separate samples at a particular depth. The range of values was greater for separate samples from one depth than for several measurements from one sample bottle. With one exception, the mean values for both nitrogen and methane concentrations from all sample bottles from a given depth were judged to be statistically equivalent at the 95% confidence level according to the t test (Huntsberger, 1961). The exception, the nitrogen concentrations for Van Dorn cast number one, was higher than those of casts numbers two and three. The variations in dissolved methane concentrations were slightly greater than those in the nitrogen determinations. In all cases, however, the precision of the analyses was within + 7 % of the average and generally within f5 %. Conclusions The data gathered by this study indicate that collection and storage of water samples in the dissolved gas sampling bottles is a method that maintains dissolved nitrogen and methane
concentrations constant during storage. The overall method of collection, filling, storing, and analyzing is precise to within + 7 % or less. The sampling bottles offer a convenient means of filling and transferring the water sample to the gas stripping chamber. When this method of sample collection and storage is used, the largest source of analytical error for this study was apparently the instrumentation. Literature Cited Huntsberger, D . V., “Elements of Statistical Inference,” Allyn and Bacon, Boston, Mass., 1961. Hydro Products, OEC, Seahorse 2 (4) (1967). Swinnerton. J. W.. Linnenbom. V. J., Cheek, C. H., Anal. Chem. 34, 483 (1962a). Swinnerton, J. W., Linnenbon, V. T., Cheek, C. H., ibid. 34. 1509 (1962b). Weimer, W. C. ‘“Some Considerations of the Chemical Limnology of Lake Mary, Vilas County, Wisconsin,” M.S. Thesis, Water Chemistry Program, University of Wisconsin, Madison, Wis., 1970. Received for review Jan. 22, 1971. Accepted April 6, 1971. This investigation was supported by a National Defense Education Act Title IV Fellowship, Federal Water Pollution Control Administration training Grant 5TI- WP-184, and the University of Wisconsin Engineering Experiment Station, Civil Engineering Dept., and Water Resources Center.
Rapid Uptake of Mercuric Ion by Goldfish Colin E. McKone,‘ Roger G. Young, Carl A. Bache, and Donald J. Lisk2 Department of Entomology, Cornel1 University, Ithaca, N. Y 14850 Experimental Mercuric ion has been shown to be rapidly absorbed from water by goldfish. The extent of absorption is dependent on mercury concentration and time of exposure. As has been previously shown with other metals, mercury was found to concentrate initially in the external mucus secreted by the fish. The presence of mercury in water appeared to stimulate this secretion.
R
ecent high levels of mercury in fish and the environment have been well publicized (Klein and Goldberg, 1970; Chem. Eng. News, 1970b; Chem. Eng. News 1970a; Znd. Res., 1970; Parker, 1970; Zwerdling, 1970). Microbiological methylation of mercury and the resultant presence in fish of highly toxic methylmercuric salts (Westoo, 1969; Westoo and Rydalv, 1969) are of particular concern. Since mercuric ion is one of the major forms of mercury as an initial industrial pollutant, we found it interesting to study the rate of absorption of this ion by fish.
1 Present address : Weed Research Organization, Agricultural Research Council, Begbroke Hill, Savoy Lane, Yarnton, Oxford, England. 2 To whom correspondence should be addressed.
1138 Environmental Science & Technology
Goldfish (Carassius auratus) were used for this study. In the first experiment, 50 fish ranging in size from about 4 to 6 cm and weighing between 1 and 3.5 grams were placed in a 57-liter aquarium with 50 liters of distilled water containing 0.25 ppm of mercury as mercuric chloride. The temperature was maintained at 21OC. The water volume was sufficiently large to obviate the need for aeration. Two grams of Strike fish food (Agway, Inc., Ithaca, N. Y.) was added daily, and was rapidly and totally consumed. At specific intervals fish were removed in groups of four, adhering water was removed by blotting and each was freeze-dried and mechanically ground and mixed. One gram of each sample was pelleted and burned in a modified Schoniger flask (Gutenmann and Lisk, 1960). Mercury was determined colorimetrically as the dithizonate. The method was sensitive to about 0.25 ppm of mercury in fish. With this method, the recovery of 0.5 ppm of mercury added to two samples of fish as mercuric chloride was 102 and 108%. Apparent mercury in unexposed goldfish was less than 0.25 ppm. Results Figure 1 illustrates the rapid uptake of mercury by the fish as a function of time. In preliminary experiments it was found that goldfish died within 4 hr when exposed to 1 ppm of mercury as mercuric chloride. The fish exhibited no outward signs of toxicity during the test period in the 0.25 ppm solution used.
