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Ref. No. [UMCES] CBL 2016-014
ACT VS16-05
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The HACH DS5X reported data throughout the entire deployment and generated 2827
observations based on its 60 minute sampling interval over the 17 week deployment. However,
only 2434 of the measurements were considered acceptable based on our approach of excluding
values that were more than 2 mg/L from reference sample over a similar timeframe. The accepted
data resulted in a data completion rate for this deployment of 86%. Time series results of the
DS5X and corresponding reference DO results are given in figure 8. Ambient DO measured by the
DS5X ranged from 1.88 to 10.97 mg/L while the range captured by reference samples was 3.630 to
9.851 mg/L. The average and standard deviation of the differences between instrument and
reference readings (limited to ± 2.0 mg/L DO; n=53 of 129 potential observations) were 0.62 ±
0.744 mg/L, with a total range in the differences of -1.923 to 1.970 mg/L.
There was a small, but
statistically significant, drift in instrument offset over time (slope = 0.019 mg/L/d; r
2
= 0.52;
p<0.0001). This rate would include any biofouling effects as well as any electronic or calibration
drift.