9409

• UCREFRP Catalog Number: 9409
• Author: Spahr, N. E. and R. W. Boulger.
• Title: Interim Results of Quality-Control Sampling of Surface Water for the Upper Colorado River national Water-Quality Assessment Study Unit, Water Years 1995-96.
• USFW Year: 1997.
• USFW - Doc Type: 97-4227,
• Copyright Material: NO

Table 12. Summary of differences between environmental and concurrent-replicate samples for nutrients and organic carbon

[Lowest rounding unit is equal to the magnitude of the least significant figure]

Percent of samples Percent of samples Percent of samples
Constituent within plus or minus 1 within plus or minus 2
with no difference lowest rounding unit lowest rounding units
Ammonia 86 100 100
Dissolved ammonia plus organic 86 100 100
Total ammonia plus organic 86 86 86
Nitrite 100 100 100
Nitrite plus nitrate 71 71 86
Dissolved organic carbon 43 57 71
Suspended organic carbon 43 43 71
Dissolved phosphorus 71 86 86
Total phosphorus 29 57 71
Orthophosphate 100 100 100

Post-Processing Split Replicates

sources of variability resulting from sample
shipping and analysis. Variability resulting from
sample collection and processing is not evaluated
by post-processing split-replicate sampling. The
distribution of collection of the post-processing
split-replicate samples by site and date is shown in
figure 4.

A post-processing split replicate is a
processed sample that is poured into identical bottles
and thus split into two separate samples (split A
and split B). Split A and split B are submitted to
the laboratory for analysis as unique samples.
These pairs of samples help to evaluate the potential

24 Interim Results of Quality-Control Sampling of Surface Water for the Upper Colorado River National Water-Quality
Assessment Study Unit, Water Years 1995-96