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All sample handling, analysis, storage,
and data reporting adhere to QA/QC guidelines established in the
Handbook of Methods for Acid Deposition Studies (EPA 600/4-87/026,
September 1987) and the Standard Methods for the Examination of Water
and Waste Water (20th edition). Within each analytical run, field and
laboratory blanks are analyzed as well as duplicate samples and check
standards (every 10 samples). All commercial standards are certified by
the National Institute of Standards and Technology (Washington,
DC).
Analytical Evaluation
Periodically, the Air Program Laboratory participates in exchange and analysis of unknown samples (USGS Analytical Evaluation Program). This program assesses the quality of our laboratory methods and procedures.
Results of U.S. Geological Analytical Evaluation Program--Spring 2009
Low Ionic Strength
Precipitation/Snowmelt Sample
| Analyte |
Most Probable Value (mg/L) |
Water Lab Reported Value (mg/L) |
Percent Difference (%) |
| Ca |
0.415 |
0.4462 |
7.52 |
| Cl |
1.78 |
1.988 |
11.69 |
| F |
0.100 |
0.0907 |
-9.30 |
| K |
0.650 |
0.7346 |
13.02 |
| Mg |
0.057 |
0.0625 |
9.65 |
| Na |
0.230 |
0.2374 |
3.22 |
| pH |
4.88 |
4.784 |
-1.97 |
| SO4 |
0.210 |
0.2033 |
-3.19 |
| Cond. |
14.0 |
13.63 |
-2.64 |
Results of U.S. Geological Analytical Evaluation Program--Fall 2009
Low Ionic Strength
Precipitation/Snowmelt Sample
| Analyte |
Most Probable Value (mg/L) |
Water Lab Reported Value (mg/L) |
Percent Difference (%) |
| Ca |
0.741 |
0.779 |
5.13 |
| Cl |
1.05 |
1.042 |
-0.76 |
| F |
0.040 |
0.036 |
-10.00 |
| K |
0.080 |
0.091 |
13.75 |
| Mg |
0.340 |
0.351 |
3.24 |
| Na |
0.321 |
0.338 |
5.30 |
| pH |
6.70 |
6.67 |
-0.45 |
| SO4 |
0.418 |
0.408 |
-2.39 |
| Cond. |
10.0 |
9.70 |
-3.00 |
Supplemental information and SRS Round Robin results can be viewed at http://bqs.usgs.gov/srs (Air Program Laboratory = Lab No. 422)
Image Credit (top): Peter Druschke (Wilderness.net image library)
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