Sampling & Monitoring for Water Pollutants Flashcards
Why do sampling or monitoring of aquatic environments? (4)
Determination of:
- overall status/condition
- changes in status/condition
- specific influences
- fitness for use
Example of specific influences?
Point sources such as combined sewer overflows
Which parameters can be monitored to determine quality? (7)
Water temperature, dissolved oxygen, pH, turbidity, fecal coliform, nitrate, phosphorus
Which parameters are assessed using different guidelines?
Nutrients [nitrate/phosphate]
Hypoxia?
Low levels of oxygen
Anoxia?
No oxygen levels
Cause of hypoxia or anoxia?
Excess organic materials - e.g. algal blooms - decomposed by microorganisms
DO levels of concern?
< 3 mg/L
DO levels considered hypoxic?
< 1mg/L
Dissolved oxygen?
how much oxygen dissolved in water & available to living aquatic organisms
2 considerations for sampling & monitoring?
- scale
- specificity, general or impacts of discrete sources
Representative sampling?
General monitoring of quality reflecting a large spatial scale
Random stratified sampling?
Randomly - selected bodies of water from categories/types
Example of different categorizations for random stratification?
Position in catchment, altitude, size, permanent/temporary, underlying geology, urban/rural
Repeated measures?
Used in combination with random stratification or representativeness
Upstream-downstream?
What changes at different points within the river as a result of a specific influencing factor?
Before-after-control-impact?
What happens if we do something to effect positive change? Is change really due to what we did?
Factors sampling may need to take into account?
- when
- where [within catchment]
- where [within river]
- midstream
- margins
- still or flowing waters
Practical limitations of sampling?
Which resources available to carry out work - time/people/equipment
Which factors does representative sampling need to consider? (3)
- flow conditions
- events & extremes
- time [season? day?]
Primary choices for sampling? (4)
Collect samples, return to lab, process, analyse?
Collect samples automatically, preserve, return to lab, process, analyse?
Measure directly, manually?
Measure directly, instrumented?
EXPENSE
How can you add value to sampling? (3)
- opportunistic deployment: co-location at sites used by others & sharing data
- experimental design to align with modelling?
- experimental design to align with stats?
Phosphorus in Chalk Streams [Test & Itchen] (4)
- combination of autosamplers & EA gauging stations used
- autosamplers on private land, limited visibility, difficult to get to, only Itchen
- if not next to gauging station, pressure sensor used alongside auto
- bucket for sites next to bridges/roads
