Question: How can we relate water quality sensor measurements to oil/gas pollution?

wmacfarl is asking a question about water-quality
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by wmacfarl | September 25, 2019 00:56 | #20979

The most commonly available electronic sensors for collecting water quality data seem to be:

  • pH
  • Temperature
  • Dissolved Oxygen
  • Conductivity
  • Turbidity
  • ORP (Oxidation-Reduction Potential)

None of these things directly test for the presence or absence of particular chemicals or contaminants.

There are also ion-selective electrode-based sensors that detect the presence of specific chemical ions. These are a lot more expensive then the other sensors -- ranging from $250 at the low end to thousands of dollars at the highe end. Common ones seem to be:

  • Nitrate
  • Ammonium
  • Chloride
  • Calcium
  • Potassium
  • Bromide
  • Copper
  • Cyanide
  • Fluoride

Which of these measures are likely to be worth collecting for communities affected by oil/gas industry related pollution?

Aimless research suggests that oil spills cause a lowering of disoolved oxygen, increased temperature, and increased pH (, that oil is less conductive than water and so significant amounts amounts of oil will lower conductivity ( but that there are lots and lots of things in refinery wastewater from different parts of the processes and some of them might increase and some might decrease conductivity (

But I don't know what I'm doing or talking about and would really appreciate insight from people who know more about the oil and gas industry or water quality monitoring.

It's nice to know what kinds of data are worth focusing on collecting, but it's also nice to be able to give people who are interested in community data-collection a clear story about the relationship between the information they are collecting and the pollutants/contamination they are worried about (even if the story isn't as simple as "this measurement means we have this chemical"....)


Hi wmacfarl,

Just some information about 3 analytical parameters that indicate the "organic load" in water. By "organic load" I mean the "sum" of organic compounds.

But it makes no distinction between compounds of mineral origin (eg petroleum and derivatives) or vegetable (vegetable oils and fats).

The original material is in Portuguese:

but Google translation helps to understand.

Best Regards, Markos

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This page from Penn State has a great summary of natural gas activity indicators, their expected levels in areas with natural gas drilling, and relevant regulations on their limits:

You have already identified a lot of the most important indicators. Core indicators are conductivity / total dissolved solids (TDS), total suspended solids (TSS), temperature, pH, and dissolved oxygen (DO). Secondary indicators are barium, strontium, sulfates, nitrates, phosphates, iron, manganese, chloride. Testing for volatile organic compounds like methane would also be of interest.

The page lists surfactants and BTEX (Benzene, Toluene, Ethyl- benzene and Xylene) as indicators, but even in a location with a known high location of fracking, there were rarely detectable levels in the water. This suggests that while it would be satisfying to communicate the direct causal link between oil/gas activity and direct detection of such contaminants, it might not actually be that common or cost effective.

Fractracker Alliance also has a good page on water parameters:

"In the event that a 'core' indicator suggests possible contamination due to extraction impacts, monitoring groups often run additional tests on their samples using secondary indicators to pinpoint the source of the problem." So we can test broadly for the core indicators, which are generally easier and less expensive to test for anyways, and do follow up testing in relevant cases.

The Fractracker Alliance also notes that visual and biological indicators can be useful for assessing natural gas activity's impact on water: Visual Indicators: Visual monitoring is an important aspect of observing water quality impacts. Observations of road erosion, sedimentation, methane bubbling, and other habitat disruption can often provide warning signs of watershed impacts not detected in quantitative measurements. Biological Indicators: Macroinvertebrate monitoring is the study of biological organisms present in a stream. “Macros” such as insects, crayfish, worms, and clams can be very sensitive to subtle water quality changes and are therefore good indicators of a stream’s overall ecological health."

Also see:

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