Environmental Products
The image-derived concentrations of suspended chlorophyll, suspended minerals, and colored dissolved organic carbon retrieved by AAI's QSC water quality application can occur in "patterns" within a water body that can be used to identify apparent point or non-point pollution source locations (e.g., shoreline sediment influx from agricultural run-off, organic influx from septic system failure, etc.). They may, for example, take the form of concentration gradients or anomalous plumes near a shoreline. Correlations of concentrations (e.g., suspended chlorophyll with colored dissolved organic carbon) can be used to diagnose the processes likely responsible for the concentration gradients or plumes, and the spatial patterns and association with land features can be used to identify likely source locations. Subtle features can be detected with the QSC Water Quality High Res Products, revealing pollution sources that are often not apparent by other means. Features can be monitored persistently to track pollution levels and monitor progress against restoration targets. Archived imagery can be used to help establish realistic restoration targets by retrieving actual chlorophyll, sediment, and CDOC concentration levels from imagery acquired decades earlier. The broad area coverage of AAI's Low Res Products can be particularly valuable for establishing targets, and monitoring progress against those targets by insuring that retrieved concentration levels and variances are regionally statistically valid. The more focused coverage of AAI's High Res Products is valuable for locating and monitoring specific source sites.
An example of a subtle apparent non-point-source pollution feature in the Patuxent River, indicated by an anomalous plume of Colored Dissolved Organic Carbon along the shoreline at Summerville Creek
Comparable levels of CDOC occur in a pond along Summerville Creek
The pattern of suspended chlorophyll concentrations suggests association with the CDOC as a nutrient source
The pond is a dammed part of Summerville Creek, and its water quality may be affected by agricultural practice (top). A close-up of the high CDOC and suspended chlorophyll area (bottom) reveals an apparent submerged source of the pollution (brown area) adjacent to the peninsula.
A second example (above) along the Patuxent River, MD is a near-shore concentration gradient of suspended sediments that may point to an agricultural runoff non-point source of pollution. A close-up of the site is shown below. Bottom sediments from runoff can be hosts to attached nutrients or other pollutants (e.g., herbicides). The pollutants can then be released during entrainment.
A chlorophyll anomaly (above) next to the sediment anomaly (previous figure) suggests a possible association between the two, with a sediment-borne nutrient influx at this site. Modest concentrations of colored dissolved organic carbon in the vicinity of the suspended chlorophyll anomaly (below) suggest algae growth, rather than decay, is occurring in the chlorophyll plume. CDOC can be an effective indicator of algae status. High CDOC concentrations can result from algal decay, and can be used to estimate the Chl_a to Phaeophytin (chlorophyll decay product) ratio.
The concentration gradients of suspended minerals can be used to identify potential non-point source locations of the influx of sediments. These are indicated in the figure below;
A close-up view (below) points to riparian buffer deficiencies as possible non-point sources of agricultural run-off pollution.
A third example of a potential non-point source of pollution along the Patuxent River, MD is shown in the area indicated below.
A close-up view (below) reveals residential Golden Beach on the northern boundary of the inlet, an agricultural area on the southern boundary, and a wetland on the western end.
The site contains a substantial chlorophyll plume (below).
The concentration pattern of colored dissolved organic carbon (below) indicates apparent algae growth and decay zones.
The suspended sediment concentration pattern (below) suggests potential nutrient source regions, apparently from agricultural run-off. A local concentration of CDOC in the sediment plume near the structures on the western part of the agricultural shoreline (see above) suggest there may possibly also be contributions from one or more leaking septic systems. This would need to be verified by field-collected water samples.
Environmental Products List