Lowlevel collection techniques for mercury in surface water

1
Low-level collection techniques for mercury in
surface water

• U.S. Geological Survey
• Low-level mercury laboratory
• Middleton, WI

2
Problem
USGS low-level Hg laboratory

• Contamination of sampling equipment
• Sample line
• Pump-head tubing
• Capsule filters
• Contamination of sampling bottles

3
Cleaning procedures(teflon sample bottles)

• Acid bath (4 N trace pure HCl)
• Heated to 65 deg. C for 48 hours
• Rinsed 3X with reagent grade water
• Rinsed with 1 Omni Trace HCl and capped
• All equipment drying in Hg-free class 100 laminar
  flow hood
• Double bagged with ID for tracking
• Ten percent of cleaned bottles are tested for Hg
  contamination

4
Cleaning procedures(sample tubing)

• Filled with 50 percent Omni Trace nitric acid
• Soaked in a 10 percent HCl bath for 7 days
• Interior surfaces dried with Hg-free nitrogen gas
• Bagged, tracked, and tested like teflon bottles

5
Cleaning procedures(capsule filters)

• Filled with Omni Trace nitric acid
• Soaked for 4 days
• Rinsed with 20 filter volumes of reagent grade
  water
• Refilled with Omni Trace HCl and soaked in a 10
  HCl bath for 3 days
• Rinsed with 20 filter volumes of reagent grade
  water
• Filled with final filter volume, capped, double
  bagged

6
Water sampling procedures

• Peristaltic pump or grab sample
• Arm length polypropylene gloves/tyvek suits
• Acidified with 1 percent (v/v) Omni Trace HCl
• Lab filtration in a class 100 clean room
  available by shipping chilled sample (4 deg. C)
  overnight to USGS low-level mercury laboratory

7
Integration of Hg and Se sampling

• Laboratory provides pre-cleaned sample containers
  and sample equipment (this is the time sink)
• Sampling procedures require arm length gloves and
  tyvek suits
• Collection of unfiltered samples minimizes field
  contamination and sampling time
• Options for laboratory filtration of water, if
  needed

8
A GSL sampling trip(no analytical costs)
Activity
Estimated cost Trip preparation
(4 hours)
280 Boat operation (10 hours)
900 3-person sampling
team (12 hours)
2,160 Round trip truck transportation to launch
site 100 Consumable sampling
supplies/equipment 220 Post-trip
sample processing (4 hours)
280 Post-trip boat maintenance (2 hours)
140 Storm contingency
1,000

Total 5,080
Analytical costs are only a small percentage of
sample collection costs
9
Mercury analysis 400. Surviving another day on
Great Salt Lake, priceless.