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**PASSIVE INTEGRATIVE MERCURY SAMPLER (PIMS)**

The PIMS (U.S. patent no. 6,129, 843) is an effective alternative to
conventional sampling for mercury vapor (Hg^0^) and is highly suitable
for long-term unattended sampling. It consists of a semi-permeable
polymeric membrane containing a mercury-sequestering reagent sealed
inside (Figure 1). Because mercury vapor readily permeates the membrane
and is rapidly oxidized and stabilized inside the membrane, sampling
intervals of weeks to months are possible. The PIMS sampling reagent is
amenable to direct analysis for mercury (no chemical treatment required)
by conventional methods (AA, AF, or ICP-MS) with virtually no
interferences. Preliminary results indicate that the PIMS is also
applicable for water sampling of neutral mercury species.

Features:

-   Passive sampling requires no pumps, traps, or electrical power.

-   Integrative sampling for up to 90 days.

-   Clean-room mercury facilities generally not required.

-   Particularly useful for applications requiring unattended sampling
    for extended periods at remote locations.

-   Sampler reagent is conveniently analyzed for mercury directly by
    ICP-MS, CVAF, or CVAA without chemical treatment.

-   Simple alternative for Hg vapor screening and detection; sampling
    precision \~ 5-10% RSD.

-   Potentially applicable for gaseous Hg sampling in soil and water.

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**Figure 1.** Free-standing PIMS configuration (left) for environmental
air sampling of Hg vapor. 1 = heat seals,

2 = polyethylene layflat tubing, 3 = Hg-stabilizing reagent inside
sampler, 4 = tether loops,

> 5 = stainless steel rods. Stainless steel canister configuration
> (right) for hanging or underwater deployment contains up to five
> individual 7.5 x 2.5-cm PIMS, mounted in an alternating 90-degree
> orientation.

*Temperature Dependence.* The sampling rate (volume of air
quantitatively sampled per unit time) increases linearly with
temperature (Figure 2). However, accurate temperature measurement during
sampling is usually unnecessary because the dependence is not great. For
example, the sampling rate at 20 ºC is only about 25% higher than at 10
ºC. In cases where the temperature cannot be estimated or if large
temperature fluctuations are anticipated, a digital temperature data
logger can be attached to the deployment canister.

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**Figure 2.** PIMS sampling rate of Hg^0^ as a function of temperature.

*Comparison to conventional air sampling.* In a separate 4-week study,
the PIMS sampling approach was compared with the conventional
pump-and-trap method at a site near a probable Hg emission source. The
overall 4-week mean Hg air concentration ([+]{.underline} 1 s.d.) for
the PIMS, estimated from experimentally-determined sampling constants
was 5.2 [+]{.underline} 1.8 ng/m^3^ (n=5) as compared with 5.1
[+]{.underline} 2.8 ng/m^3^ (n=8) measured for semi-weekly one-hour
pump-and-trap sampling.

*Long-term air monitoring*. Long-term air sampling of Hg by the PIMS in
the vicinity of a coal-fired power plant over a 12 week interval is
illustrated in Figure 3. Triplicate samplers retrieved after 4, 8, and
12-week intervals were in good agreement with the corresponding sums of
separate 4-week samples, indicating that the sampling was nearly linear
over the entire 12-week interval (the air concentration decreased
slightly during the 12 weeks). The mean air concentration of Hg vapor
determined by PIMS sampling was 25 ng/m^3^ over this time interval.
Blank concentrations have been reduced substanitally since this
experiment.

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**Figure 3.** PIMS sampling of Hg from air near a coal-fired power plant
over a 12-week period. (Blk = PIMS method blank sealed in a glass jar)

*Water sampling.* Results from a preliminary field study indicate that
the PIMS is effective for sampling gaseous Hg, and possibly other
neutral Hg species from water. A four-week PIMS deployment in a
mercury-contaminated stream produced concentration factors of greater
than 100 (concentration of Hg in PIMS reagent divided by concentration
of total Hg in filtered water). The mean mass of Hg sequestered by PIMS
at different deployment sites ranged from 0.68 to 1.86 ng and the
within-site precision for replicate PIMS averaged 15% RSD. Blank PIMS
(n=5) contained Hg near the atomic fluorescence detection limit (0.5
ng/L or 0.0025 ng/PIMS).

**References:**

1\. Brumbaugh, W.G.; Petty, J.D.; May, T.W.; Huckins, J.N. 2000. A
passive integrative sampler for mercury vapor in air and neutral mercury
species in water. Chemosphere: Global Science Change 2:1-9.

2\. Petty, J.D.; Brumbaugh, W.G.; Huckins, J.N.; May, T.W. 2000. U.S.
patent no. 6,129,843, Device for the removal and concentration of
neutral mercury species from air and water.

**For more information contact:**

Dr. William Brumbaugh \<bbrumbaugh@usgs.gov\>\
U.S. Geological Survey

Columbia Environmental Research Center

4200 New Haven Rd, Columbia, MO 65201

573-875-5399