Sampling and Measurements

Samples are collected in 3/8" diameter copper tubes, clamped at both ends. Sampling gear, advice on sampling as well as sampling instructions are made available to clients. Helium analyses are completed in 4 to 6 weeks. Tritium measurements by mass-spectrometry requires a typical storage period of 4 months. To minimize analysis time however, proportional counting is substituted albeit with some loss in resolution in the age estimate.

Dissolved Noble Gas Sampling Procedure

Note: No Luminous Watches In Sampling Area

Locate aluminum channel, wrench, tygon tubes in the crate so marked.
Place clamps in the notches of the channel (Figure 1) making sure that the copper tube is centrally positioned in the clamps.
Partially tighten clamp nuts to hold copper tube in position (Figure 2).
Attach long and short tygon tubes to the copper tube. Attach free end of the long tygon to the pump outlet (Figure 3).
Start a bubble-free, solid, slow flow (1 to 1.5L/min).
Tap on the copper tube along the full length, up and down with the wrench while flushing the tube.
When no bubbles are visible in the upper tygon tube stop flow. Make sure the copper tube is centrally positioned in the bottom clamp. Tighten one side of the clamp nut half-way, then the opposite nut 3/4 the way, then the first one all the way, and finally the opposite all the way. Tighten the top clamp in the same fashion. It is properly tight when a sudden resistance to tightening is met. The best way to monitor the proper tightness is to make sure that the squeezing edges have a gap of about 1mm around the copper tube (Figure 4).
Do not remove clamps from the copper tube.
Cap ends of the copper tube with plastic caps without shaking the water out. Attach sample identification label or identify sample on tube with indelible marker. Remove from channel, go onto next sample.
Please dry tygon tubes, wrench, channel, and the copper tubes before stowing in the cooler. For space saving considerations the copper tube sampler may be bent.

Tritium Sample Collection Procedure

Locate plastic/glass bottle. Bottles are baked and prefilled with dry argon/nitrogen to keep ambient water vapor out. Open cap only when ready to fill while pump is running.
Insert tubing 1/3rd way into the bottle and fill bottle. Pull tubing out as bottle fills. Leave 1/2”-3/4” head-space below neck.
Tighten cap firmly (not excessively). Wrap cap with parafilm strip (provided) to prevent inadvertent loosening/leaking.
Identify sample on label with waterproof marker.
Place bottle in lockable plastic bag; return bottle in original shipping cooler/crate.

Terms and Conditions

NGIL provides analytical services on groundwater samples for outside educational or commercial institutions. These are summarized below.

For more information, contact Dr. Zafer Top.

I. Services Rendered

Preliminary

Discussion on how noble gases and tritium could be suitable in a particular situation to determine groundwater ages, flow rates, aquifer recharge rates.
Advise on sampling techniques.
Provide sampling equipment, and if required, a technician for sampling.
Provide pertinent references from scientific literature, as available.

Analytical

Acknowledge receipt for samples, if required by the submitter.
Check sampler integrity, retighten clamps, identify samples that might be compromised, check inventory against the submitter's list. Notify the submitter of discrepancies and potentially compromised samples.
Degas water samples to separate and seal dissolved helium-neon, and/or argon fraction, identify samples that might be compromised, notify the submitter.
Degas water samples in Corning 1724 glass-flasks, seal and store for subsequent tritium determination.
Measure helium-neon fraction for concentration in a quadrupole mass spectrometer (or by isotope dilution in a magnetic sector mass-spectrometer, at our discretion as necessary for final precision).
Measure helium fraction for ³He/⁴He isotopic ratio, against atmospheric standards.
Measure mass-spectrometrically, the accumulated ³He in tritium samples, following appropriate waiting period, calculate tritium concentration.
Calculate tritium-helium ages. Issue a data release.
Notify submitter of results, as requested. A hard copy is always sent by mail.
Duplicate runs on a sample for helium-neon or mass-spectrometric tritium measurements can be made by prior request of the submitter.

Disclaimer
The Noble Gas Isotope Laboratory of the Rosenstiel School of Marine and Atmospheric Science, University of Miami, will make the best effort to deliver the most precise measurements. However, University of Miami cannot assume any legal or other responsibility for erroneous results. The work is a best effort. If the submitter can justify reason(s) for suspecting a result, a re-measurement can be made at the cost of the laboratory, on a resubmitted sample. A submitter is strongly advised to contact the Laboratory regarding procedures for sampling, materials, subsequent handling, storage and shipping, to minimize experimental uncertainties.

II. Definitions, Experimental Procedures

Dissolved noble gases such as helium, neon and argon have been used in groundwater/aquifer research to glean information such as the age of water and recharge rates. Tritium signal introduced by the thermonuclear bomb tests of the early 60s, provides a tool for age dating on decadal time scale. Tritium, ³H, is radioactive and decays into light helium isotope, ³He, with a half-life of 12.42y. Simultaneous measurements of tritium and helium-3 in water allow the calculation of time elapsed since the last contact of the water with the atmosphere, with certain assumptions.

Water samples for helium, neon, argon measurements are collected in 3/8" or 5/8" OD copper tubes, approximately 14" long, with clamping. Samples for tritium measurements are collected in pre-treated 1L or 0.5L glass or high density polyethylene (a second choice) bottles. Laboratory procedures for helium, neon, and argon measurements consist of gas extraction under vacuum, separation of helium-neon fraction, splitting of helium-neon fraction (when required), sealing of helium-neon fraction in Corning-1724 glass ampoules, purification and sealing of argon fraction, and measurements in statically operated, either a 25cm or 15cm radius, magnetic-sector gas mass-spectrometers. Absolute concentrations of neon is measured routinely in a quadrupole, or in a 15cm radius, magnetic sector mass-spectrometer with isotope dilution (as may be required for higher precision). The precision of He and Ne measurements varies between 0.25 and 2% depending on the technique.

Laboratory procedures for tritium measurements consist of transferring of the water from collection bottles into a Corning 1724 glass flask in vacuum, completely degassing the sample, sealing the flask and storing the sample at -20°C. Storage time depends on the expected tritium levels and mass of the sample. For example, a 700g sample with 10TU (1 TU=1 Tritium/1018 Hydrogen) can be analyzed after a month's storage. Following a measured storage period, the sample is analyzed for accumulated ³He, and the tritium concentration is calculated. The precision quoted for a groundwater samples is 1.5% or 0.01TU, whichever is greater. Measurements are calibrated with an atmospheric helium aliquot; accuracy is monitored by running NIST standard(s) with the unknowns.

III. Price Schedule

Mass-spectrometric helium isotope ratio, ³He/⁴He with a precision of 0.5%. The result is expressed with respect to the standard atmospheric ratio. This analysis also includes ⁴He (total helium), ³He, and neon concentration measurement with precisions of 0.5%, 0.5%, and 2%, respectively. Sampling devices are provided without cost, with prior arrangement. $300.00 per sample.
Mass-spectrometric tritium determination with a precision of 1.5% or 0.01TU (detection limit 0.015TU) or better. Clients are advised to obtain their own 1L plastic bottles for sample collection. $375.00 per sample.
Tritium-³He age calculation is included in the measurement cost. Further help with age calculations and general interpretation can be arranged at a negotiated price.
A nominal shipping and handling charge applies.
For institutions without federal tax exemption a surcharge may be applicable.

IV. Conditions

At our discretion, we may request payment with order, and withhold measurement results until payment has been received.
Contract: Due to administrative and legal input required for a contract, such arrangement will carry a surcharge. The amount of surcharge is larger of $5,000 or 50% of the contract amount. Any contract must include the procedures, specifications and prices precisely as listed in this schedule. University of Miami will not accept any commitments to replace or add to the ones stated in this schedule. The work is a best effort.
Loss of sampling devices while in the possession of submitter requires compensation equivalent to replacement value of said equipment.

V. Early References On The Method

Clarke, W.B. and G. Kugler, Dissolved helium in groundwater: A possible method for uranium and thorium prospecting, ECON. GEOL., 68, 243-251, 1973.

Clarke, W.B., W.J. Jenkins, and Z. Top, Determination of tritium by mass-spectrometric measurement of 3He, INTERNAT. J.APPL. RAD. ISOT.,27,515-522, 1976.

Clarke, W.B., Z. Top, A.P. Beavan, and S.S. Gandhi, Dissolved helium in lakes: uranium prospecting in the Precambrian terrain of central Labrador, ECON. GEOL., 72, 233-242, 1977.

Sampling and Measurements Samples are collected in 3/8" diameter copper tubes, clamped at both ends. Sampling gear, advice on sampling as well as sampling instructions are made available to clients. Helium analyses are completed in 4 to 6 weeks. Tritium measurements by mass-spectrometry requires a typical storage period of 4 months. To minimize analysis time however, proportional counting is substituted albeit with some loss in resolution in the age estimate. Dissolved Noble Gas Sampling Procedure Note: No Luminous Watches In Sampling Area Locate aluminum channel, wrench, tygon tubes in the crate so marked. Place clamps in the notches of the channel (Figure 1) making sure that the copper tube is centrally positioned in the clamps. Partially tighten clamp nuts to hold copper tube in position (Figure 2). Attach long and short tygon tubes to the copper tube. Attach free end of the long tygon to the pump outlet (Figure 3). Start a bubble-free, solid, slow flow (1 to 1.5L/min). Tap on the copper tube along the full length, up and down with the wrench while flushing the tube. When no bubbles are visible in the upper tygon tube stop flow. Make sure the copper tube is centrally positioned in the bottom clamp. Tighten one side of the clamp nut half-way, then the opposite nut 3/4 the way, then the first one all the way, and finally the opposite all the way. Tighten the top clamp in the same fashion. It is properly tight when a sudden resistance to tightening is met. The best way to monitor the proper tightness is to make sure that the squeezing edges have a gap of about 1mm around the copper tube (Figure 4). Do not remove clamps from the copper tube. Cap ends of the copper tube with plastic caps without shaking the water out. Attach sample identification label or identify sample on tube with indelible marker. Remove from channel, go onto next sample. Please dry tygon tubes, wrench, channel, and the copper tubes before stowing in the cooler. For space saving considerations the copper tube sampler may be bent. Tritium Sample Collection Procedure Locate plastic/glass bottle. Bottles are baked and prefilled with dry argon/nitrogen to keep ambient water vapor out. Open cap only when ready to fill while pump is running. Insert tubing 1/3rd way into the bottle and fill bottle. Pull tubing out as bottle fills. Leave 1/2”-3/4” head-space below neck. Tighten cap firmly (not excessively). Wrap cap with parafilm strip (provided) to prevent inadvertent loosening/leaking. Identify sample on label with waterproof marker. Place bottle in lockable plastic bag; return bottle in original shipping cooler/crate. Terms and Conditions NGIL provides analytical services on groundwater samples for outside educational or commercial institutions. These are summarized below. For more information, contact Dr. Zafer Top. I. Services Rendered Preliminary Discussion on how noble gases and tritium could be suitable in a particular situation to determine groundwater ages, flow rates, aquifer recharge rates. Advise on sampling techniques. Provide sampling equipment, and if required, a technician for sampling. Provide pertinent references from scientific literature, as available. Analytical Acknowledge receipt for samples, if required by the submitter. Check sampler integrity, retighten clamps, identify samples that might be compromised, check inventory against the submitter's list. Notify the submitter of discrepancies and potentially compromised samples. Degas water samples to separate and seal dissolved helium-neon, and/or argon fraction, identify samples that might be compromised, notify the submitter. Degas water samples in Corning 1724 glass-flasks, seal and store for subsequent tritium determination. Measure helium-neon fraction for concentration in a quadrupole mass spectrometer (or by isotope dilution in a magnetic sector mass-spectrometer, at our discretion as necessary for final precision). Measure helium fraction for ³He/⁴He isotopic ratio, against atmospheric standards. Measure mass-spectrometrically, the accumulated ³He in tritium samples, following appropriate waiting period, calculate tritium concentration. Calculate tritium-helium ages. Issue a data release. Notify submitter of results, as requested. A hard copy is always sent by mail. Duplicate runs on a sample for helium-neon or mass-spectrometric tritium measurements can be made by prior request of the submitter. Disclaimer The Noble Gas Isotope Laboratory of the Rosenstiel School of Marine and Atmospheric Science, University of Miami, will make the best effort to deliver the most precise measurements. However, University of Miami cannot assume any legal or other responsibility for erroneous results. The work is a best effort. If the submitter can justify reason(s) for suspecting a result, a re-measurement can be made at the cost of the laboratory, on a resubmitted sample. A submitter is strongly advised to contact the Laboratory regarding procedures for sampling, materials, subsequent handling, storage and shipping, to minimize experimental uncertainties. II. Definitions, Experimental Procedures Dissolved noble gases such as helium, neon and argon have been used in groundwater/aquifer research to glean information such as the age of water and recharge rates. Tritium signal introduced by the thermonuclear bomb tests of the early 60s, provides a tool for age dating on decadal time scale. Tritium, ³H, is radioactive and decays into light helium isotope, ³He, with a half-life of 12.42y. Simultaneous measurements of tritium and helium-3 in water allow the calculation of time elapsed since the last contact of the water with the atmosphere, with certain assumptions. Water samples for helium, neon, argon measurements are collected in 3/8" or 5/8" OD copper tubes, approximately 14" long, with clamping. Samples for tritium measurements are collected in pre-treated 1L or 0.5L glass or high density polyethylene (a second choice) bottles. Laboratory procedures for helium, neon, and argon measurements consist of gas extraction under vacuum, separation of helium-neon fraction, splitting of helium-neon fraction (when required), sealing of helium-neon fraction in Corning-1724 glass ampoules, purification and sealing of argon fraction, and measurements in statically operated, either a 25cm or 15cm radius, magnetic-sector gas mass-spectrometers. Absolute concentrations of neon is measured routinely in a quadrupole, or in a 15cm radius, magnetic sector mass-spectrometer with isotope dilution (as may be required for higher precision). The precision of He and Ne measurements varies between 0.25 and 2% depending on the technique. Laboratory procedures for tritium measurements consist of transferring of the water from collection bottles into a Corning 1724 glass flask in vacuum, completely degassing the sample, sealing the flask and storing the sample at -20°C. Storage time depends on the expected tritium levels and mass of the sample. For example, a 700g sample with 10TU (1 TU=1 Tritium/1018 Hydrogen) can be analyzed after a month's storage. Following a measured storage period, the sample is analyzed for accumulated ³He, and the tritium concentration is calculated. The precision quoted for a groundwater samples is 1.5% or 0.01TU, whichever is greater. Measurements are calibrated with an atmospheric helium aliquot; accuracy is monitored by running NIST standard(s) with the unknowns. III. Price Schedule Mass-spectrometric helium isotope ratio, ³He/⁴He with a precision of 0.5%. The result is expressed with respect to the standard atmospheric ratio. This analysis also includes ⁴He (total helium), ³He, and neon concentration measurement with precisions of 0.5%, 0.5%, and 2%, respectively. Sampling devices are provided without cost, with prior arrangement. $300.00 per sample. Mass-spectrometric tritium determination with a precision of 1.5% or 0.01TU (detection limit 0.015TU) or better. Clients are advised to obtain their own 1L plastic bottles for sample collection. $375.00 per sample. Tritium-³He age calculation is included in the measurement cost. Further help with age calculations and general interpretation can be arranged at a negotiated price. A nominal shipping and handling charge applies. For institutions without federal tax exemption a surcharge may be applicable. IV. Conditions At our discretion, we may request payment with order, and withhold measurement results until payment has been received. Contract: Due to administrative and legal input required for a contract, such arrangement will carry a surcharge. The amount of surcharge is larger of $5,000 or 50% of the contract amount. Any contract must include the procedures, specifications and prices precisely as listed in this schedule. University of Miami will not accept any commitments to replace or add to the ones stated in this schedule. The work is a best effort. Loss of sampling devices while in the possession of submitter requires compensation equivalent to replacement value of said equipment. V. Early References On The Method Clarke, W.B. and G. Kugler, Dissolved helium in groundwater: A possible method for uranium and thorium prospecting, ECON. GEOL., 68, 243-251, 1973. Clarke, W.B., W.J. Jenkins, and Z. Top, Determination of tritium by mass-spectrometric measurement of 3He, INTERNAT. J.APPL. RAD. ISOT.,27,515-522, 1976. Clarke, W.B., Z. Top, A.P. Beavan, and S.S. Gandhi, Dissolved helium in lakes: uranium prospecting in the Precambrian terrain of central Labrador, ECON. GEOL., 72, 233-242, 1977.