Water Quality Parameters

Sampling parameters vary among monitoring levels. At a moderate level, quality parameters are generic. At the highest monitoring level, quality parameters are more focused on contaminants of concern. Quality can be measured in the field, but more accurately measured via laboratory equipment. Thus making it extremely important to collect and preserve samples after a rain event, if an on-site laboratory is unavailable. 

Physical parameters are evaluated by test methods that can be completed in the lab or by field test. TSS and TDS are the result of erosion and particles carried by the runoff.  Physical parameters are monitored by:

  • pH probe-measures the acidity of water quality samples through the activity of hydrogen ions. Results are manually recorded after probe stabilizes.
     When: Immediately upon collection of samples.
     Where:
    In the field or laboratory.
  • Conductivity probe- measures the ability of a solution to conduct current through ion transport.  Results are manually recorded after probe stabilizes.
     When: Immediately upon collection of samples.
     Where: In the field or laboratory.
  • TSS/TDS analysis-
    -Total suspended solid (TSS)-is the mass per volume of particles held in suspension for a well mixed
      sample. Measured using Standard Methods 2540D.
       When: Immediately upon collection of samples.
       Where:
    In the laboratory.
    -Total dissolved solids (TDS) can then be calculated by baking off the sample leaving a residue. Measured
      using Standard Methods 2540D.
       When: Immediately upon collection of samples.
       Where:
    In the laboratory.

The results can be used to predict the levels of other potential contaminants.

Total nitrogen and total phosphorus can enter a water system through industrial emissions or from soil, plant and animal matter. Chloride, nitrate, nitrite and ortho-phosphate are the ionic species of these nutrients. Chloride is a result of salt used on pavement during the winter months to prevent icing. Nutrients are tested using the following devices:

  • Spectrophotometer-determines trace levels of ions in solution.  The system uses an ion exchange resin to separate the ion mixture with suitable detection of the ions as they exit the ion exchange columns through the use of the Modified EPA Method 300.1.
     When:
    Within 24 hours of collection for nutrients. In 28 days of collection for Chloride.
     Where: In the laboratory.

  • HPLC-uses absorbance of light at a specific wavelength through  the process of persulfate digestion.
     When: Within 24 hours of collection unless properly preserved.
     Where: In the laboratory. 

Target metals may include cadmium, copper, chromium, lead and zinc. Cadmium and chromium are a result of industrial emissions such as the burning of coal. The other elements may be used to coat units used to transport runoff such as pipes. Over time the coating wears away and the metals become dissolved in the runoff. Values can be detected through the use of a:

  • Graphite furnace-utilizes the Zeeman Effect. In essence the sample is heated electrically to create a dissociation of free atoms through the Modified Method 7010.
     When:
    Within 6 months of collection.
     Where: In the laboratory.