WATER QUALITY--Collecting Water Samples for Stable Isotope Analysis
In Reply Refer To: October 27, 1981
EGS-Mail Stop 412
QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 82.01
Subject: WATER QUALITY--Collecting Water Samples for Stable
Isotope Analysis
The attached instructions describe approved methods for the
collection of water samples for analysis of the stable
isotopes of hydrogen, oxygen, and carbon.
These instructions will be incorporated into a forthcoming
TWRI on sampling methods.
R. J. Pickering
Chief, Quality of Water Branch
Attachment
WRD Distribution: A, B, S, FO, PO
Key Words: water quality, sampling, stable isotope analysis
This memorandum does not supersede any previous memorandum.
Collection of Water Samples for Stable Hydrogen and
Oxygen Isotope Analysis
1. Application
This method may be used to collect water samples for
analysis of the ratios of hydrogen and oxygen isotopes.
2. Interferences
2.1 Samples containing extremely high sulfur
concentrations produce S02 which interfers with the analysis
unless special precautions are taken. Notify the Analytical
Services Coordinator of samples with high sulfate
concentrations.
2.2 Organic carbon in samples with high organic contents
may exchange with the carbon in the C02 used for sample
equilibration, resulting in poor analyses.
3. Apparatus
3.1. Standard, approved sample collection devices are
satisfactory for this procedure.
3.2. Sample bottle, 2-ounce, glass with Polyseal cap (cap
with plastic conical insert). van Waters and Rogers
Scientific No. 16151-049 bottle; Van Waters and Rogers
Scientific No. 16217-045 cap; or equivalent.
4. Reagents
Mercuric chloride tablet containing 10 mg HgCl2 in a NaCl
base.
Procedures have been updated since this memorandum was issued;
See http://isotopes.usgs.gov/lab/instructions.html9
Use of mercury is no longer recommended.
5. Procedure
5.1. Collect sample by approved method (Guy and Norman,
1970; Wood, 1976).
5.2. A filtered sample is preferred but is not required.
5.3. Rinse the sample bottle and fill with sample to the
shoulder leaving an air space.
5.4. Add 1 HgC12 tablet.
5.5. Cap tightly and ship.
References
Guy, H. P., and Norman, V. W., 1970, Field methods for
measurement of fluvial sediment, Techniques of Water-
Resources Investigations of the United States Geological
Survey, Book 3, Chapter C2, p. 59.
Wood, W. W., 1976, Guidelines for collection and field
analysis of ground-water samples for selected unstable
constituents, Techniques of Water-Resources Investigations
of the United States Geological Survey, Book 1, Chapter D2,
p. 24.
Collection of Water Samples for Stable
Carbon Isotope Analysis
1. Application
1.1. This method may be used to collect water samples for
analysis of the ratios of the stable carbon isotopes.
1.2. Water may contain a number of dissolved inorganic
carbon species including bicarbonate, carbonate, carbonic
acid, carbon dioxide, and others. The analysis provides the
stable isotopic composition of the sum of tnese species.
2. Interferences
Sulfate concentrations exceeding 500 mg/L may interfere
necessitating a correction to the data (A. Hassan, 1981,
Northeastern Region, written communication).
3. Apparatus
3.1. Standard, approved sample collection devices are
satisfactory for this procedure.
3.2. Sample bottle, 1 liter, glass with polyseal cap (cap
with plastic conical insert). Van Waters and Rogers
Scientific No. 16151-129 bottle; Van Waters and Rogers
Scientifc No. 16217-125 cap, or equivalent. Teflon-coated
screw caps provide a better seal and may be preferable in
many cases.
3.3. Plastic syringe, 50-mL capacity, Van Waters and
Rogers Scientific No. BD5663 or equivalent. Attach 15 cm of
Tygon tubing to tip.
4. Reagents
Ammoniacal strontium chloride hexahydrate solution: dissolve
1 pound (453 g) of reagent grade SrC12.6H20 in 4 pounds
(1812 g) concentrated reagent grade NH40H. Allow the solution
to remain undisturbed for 2 days. Decant the clear solution
into glass field reagent bottles and seal tightly. Solution
is stable for several years as long as it is tightly sealed
to prevent contamination with atmospheric C02.
5. Procedure
5.1. Collect sample by approved method (Guy and Norman,
1970, Wood, 1976).
5.2A. Filter surface water samples containing carbonate
sediments.
5.2B. Do not filter ground water samples .
5.3. Rinse a clean sample bottle with water to be sampled.
5.4. Fill sample bottle to about 90 percent of capacity
with sample.
5.5. Rinse syringe and Tygon hose with about 10 mL of
ammoniacal strontium chloride solution and discard rinse.
5.6. Add 50 mL of ammoniacal strontium chloride reagent
(see NOTE 1), cap bottle tightly, wrap cap with plastic
electrical tape to prevent loosening, and ship.
NOTE 1. If the water contains over 600 mg/L alkalinity,
250 mL of sample and 15 mL ammoniacal strontium chloride is
sufficient and preferable.
References
Guy, H. P., and Norman, V. W., 1970, Field methods for
measurement of fluvial sediment, Techniques of Water-
Resources Investigations of the United States Geological
Survey, Book 3, Chapter C2, p. 59.
Wood, W. W., 1976, Guidelines for collectin and field
analysis of ground-water samples for selected unstable
constituents, Techniques of Water-Resources Investigation
of the United States Geological Survey, Book 1, Chapter D2,
p. 24.