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Inferences about point source loadings from upstream/downstream river monitoring data
1International Joint Commission, 100 Ouellette Ave., N9A 6T3, Windsor, Ontario, Canada.
Environmental Monitoring and Assessment
|November 19, 2013
Summary
Monitoring toxic pollution in the Niagara and Detroit Rivers is challenging due to numerous sources and analytical errors. This study compares two programs that used upstream/downstream sampling to estimate toxic loadings indirectly.
Area of Science:
- Environmental Chemistry
- Water Quality Monitoring
- Toxicology
Background:
- Niagara and Detroit Rivers face pollution from diverse point and non-point sources.
- Direct monitoring of these sources is difficult, costly, and prone to analytical errors.
Purpose of the Study:
- To compare monitoring programs by the Niagara River Toxics Committee (NRTC) and the Upper Great Lakes Connecting Channels Study.
- To discuss data analysis challenges encountered in indirect source monitoring.
Main Methods:
- Utilized upstream/downstream sampling at river heads and mouths for indirect source monitoring.
- Employed paired sample analysis to determine differential loadings.
- Applied maximum likelihood estimation for data below detection limits.
Main Results:
- Developed a method to estimate total point source load by subtracting non-point sources and losses (volatilization, settling, degradation).
- Identified and discussed data analysis challenges specific to this indirect monitoring approach.
Conclusions:
- Indirect monitoring via upstream/downstream sampling is a viable strategy for assessing toxic loadings in large river systems.
- Addressing analytical limitations, such as values below detection limits, is crucial for accurate load estimation.
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