Water Quality with Russel Barsh, Nov 8, 2008 · 10 November 2008, 12:22 by Julie Loyd
If you click on underlined words, they will link to explanatory web pages, usually Wikipedia.
Present: Fred & Donna A, Isa D, Laurie G, Robin H, Claire H, Charlie & David & Julie L, Alison P, Betsy & Bob S, Gretchen & Stan W.
Russel Barsh gave the talk and Madrona Murphy acted as his lab assistant.
Purpose: To recruit and train people to monitor our surface and well water, hopefully monthly. They would look at contaminants that could affect the nearshore fish habitat. They would be responsible for maintaining the water testing equipment, which would be available for other projects. Training and further equipment will be available in the future.
Terminology: Ppm, ppb, or ppt are parts per million, billion, or trillion. Mg/L is milligrams per liter, µ/L is micrograms per Liter – equivalent to ppm and ppb. SJC is San Juan County. “We” is KWIAHT, Barsh and Murphy’s independent Lopez-based lab.
Overview: When we test for surface water contaminants, we concentrate on what’s easy to test for. Nitrates and phosphates, two nutrients pollutants in water, are fast and cheap to measure reliably. On the other hand, things like arsenic, widespread in the county, and toxic at extremely small quantities, are difficult to measure accurately.
We found pyrethroid pesticides at every level in the county, averaging 1 ppb, but testing requires more than desktop equipment. Generally pyrethroids are neurotoxins that interfere with the electrolytes that maintain nerve axons. Either it shuts the axon down or causes signal stutter. They’re derived from a waxy toxin that chrysanthemums, for instance, use to prevent insects from chewing on them, and are not soluble. Pyrethrin is also moderately toxic to mammals. It’s got a benzine ring and a tail, which chemical companies have tinkered with to make it more toxic to insects and less to mammals. However, it then is more toxic to fish and amphibians as well. Because they’re waxy they get stuck in silt, and average about a month of persistence. Some are stable in cool, dark, non-acid fresh water and and last for years. So, they have extreme acute toxicity but don’t last.
In SJC, we use about 150 pesticides, half have pyrethrins. Most of our farmers are organic in this county. The major users are the three pest control companies, bug spray, and garden products (which decreasing numbers of people use). Silt washes off gardens and gets into the food chain through detritivores, or when water is turbid and fish run silt through their gills.
We want people to switch to products that are less toxic to fish. Allethrin is a trillion times less toxic to fish than bifenthrin. We’re trying to convince the County to measure pyrethroids on a regular basis. We want to develop a list of all the compounds and rank them by their effect. Gretchen W has a table of all the active ingredients in products sold in the County, with toxicity to honeybees, fish, and mammals.
Stan: If one sprays one’s house for termites, what can be done to reduce toxicity around the house?
Russel: Light and warmth. It lasts about a month.
Pollutants We Can Test
1. Nutrients:
Nitrates: NO3. All living things use nitrogen to build proteins. Nitrates are the form in which nitrogen is taken up and excreted. 1 – 20 ppm in our waters is expected.
Failed septic systems and concentrations of livestock pump nitrates into the water. In enclosed areas such as the upper end of Eastsound, where the water can sit for days without moving, you get algal blooms. Everything gets green and slimy. Eventually, because of reduced oxygen, habitat is compromised and animals die or leave.
Phosphates: PO4. Phosphates have been historically boosted by people using fertilizers and laundry soaps until about 25 years ago.
At very high levels of nitrates or phosphates, the water starts to taste funny, but they’re not really toxic to humans. They change ecological processes and are a signal for problems with our handling of human and animal waste.
Nitrates and Phosphates are easy to measure with tabletop equipment.
2. Pyrethrins are hard to measure, though they’re highly toxic. (See above).
3. Surfactants (soap) are a class of chemicals that we use a lot, because they are designed to allow oil and water to combine: Candy, plastics, motor oil, gasoline, soap, shampoo, laundry soap, dish soap. In SJC, we find about 1 ppm on average. That’s a threshold level of concern. The EPA’s recommended drinking water standard is 1/2 ppm. That matters for fish and amphibians, because it disrupts their membranes. It can suffocate fish, cause disease and fungal infections in amphibians, and pop fish eggs. For insects, surfactants are also effective at the ppm level, though there’s less information on insects.
Soaps are sometimes recommended as an alternative to pesticides. A surfactant spray plugs the speracles, the tiny pinholes in the insects’ armor through which they breathe. At lower levels, it probably also disrupts membrane function and oxygen exchange across membranes. Phosphates are builders that enhance surfactants. Once phosphates were removed, the surfactant strength in soaps were increased.
Fred: In terms of environmental impact, won’t impacting insects be more important than impacting fish?
Russel: Yes, everything eats insects. The four standard animals used to test a new product are the rat (a stand-in for humans), ...
Stan: Only Republicans! (General laughter, then a brief moment of remorse.)
Russel: The rat, the rainbow trout, a world-wide standard that is closely related to salmon, the honeybee, and daphnia magna, the water flea. Much more important than daphnea would be aquatic insect larvae, which everything eats.
The word “surfactants” represents whole families of chemicals. There are non-ionics, cationics, and weird ones with charges distributed around the molecules. Sodium dodecyl sulfate, SDS, or Sodium Lauryl Sulfate is extremely persistent in the environment, used in toothpaste and soaps. We report surfactant presences as equivalences to SDS.
MBAS method is used to test for anionic surfactants, which are about half of the surfactants Americans use. (Non-ionics are used by hospitals and various industrial de-greasers). MBAS sometimes cross-reacts with heavy nitrate loads. It’s generally considered by chemists that the MBAS tendency to overreact with other chemicals offsets the fact that it doesn’t react at all with a lot of the surfactants that are out there. It forms a brilliant blue that sticks to the sample.
In the environment, surfactants have a varied lifespan.
5. Phenol is a benzene ring with an OH hat on it, one of the simplest of the petroleum derivatives. It ends up in all bulk products made from petroleum; gasoline, asphalt. Because it’s easy to measure it’s an indicator for the larger family of petroleum derivatives in the environment. The test creates a chromophore that locks onto the molecule. The new chemical bonds that form changes the color of the indicator, and you can then determine the concentration of the target. It will always underestimate by about 100-fold how much is out there.
In water, we’ve tested levels around 10 ppm, and in sediment levels of about 100 – 200 ppm, which is a level of concern. If you mix phenol with water it produces carbolic acid, a disinfectant. Toxic to people at about a grain of salt’s worth. In the environment it lasts a few months, so it’s not a big accumulative signal. If you find this in your well water, you have a big problem.
6. Arsenic, Cadmium, and other heavy metals: Very toxic. In SJC, we have a metal-rich environment since this area just started eroding about 10 million years ago. There’s a lot of Manganese, Iron, Nickel, Chromium, and Silver in the water, enough to make measuring Cadmium by desktop means unreliable – too many chances of a false positive. Heavy metals are serious enough in terms of federal regulations that we might be able to get the County to screen for it.
We are in the plume direction of the Tacoma arsenic smelter, now closed. We still see lead, arsenic, etc coming in from fossil-fuel burning plants here and in Asia – a continuous rain of airborne particles. Arsenic was applied as a pesticide in our orcharding days as well.
Mammals are more tolerant of copper and zinc than marine organisms. It’s used in anti-fouling paint and electronic equipment. Copper is really easy to reliably test for using a colorimetric test, though neither Cu and Pb (lead) are tested for by all SJC water systems.
Fred: Copper Sulfate is the recommended treatment for anthracnose in apples. It’s approved for organic certification.
Russel: Organic certification has to do with effects on people. BT kills butterflies. Rotenone kills fish. The good news is that if you apply it in an orchard that’s not draining into the water, it will bind with the humus in the garden rather than drain. Plants and mosses absorb copper. We don’t see a lot of Cu in surface waters in SJC. The assumption is that the Cu and Zn found in marine waters comes from boats.
Water hardness comes from Calcium carbonate CaCO3 and Magnesium carbonate MgCO3. You can’t do anything about it, it’s there geologically. It’s an easy chromometric test. Our tester could only go up to 200 ppm, and everywhere in the county we found more than that, how much more isn’t known. It’s not in a form our body can absorb. We absorb Ca and Mg from meats, fruits, and vegetables.
The rotten egg smell in some water systems is caused by Iron and Sulfur interacting with an infection of Fe and S reducing bacteria. It won’t hurt you but it makes the water taste bad. SJC is iron-rich but there’s not that much sulfur.
7. Salt. We have salt water intrusion in many places in SJC. Limestone rich rocks are responsible not only for water hardness but also contain salt. It won’t kill you, but it doesn’t take much to make the water unpalatable. In your testing, look for Cl, chloride, the dissolved chloride ion. It could come from ocean-bottom bedrock or seawater intrusion. You can tell which by looking at it over time. If it’s saltwater intrusion, it’ll get worse. If it’s from bedrock and there’s recharge, it will improve.
Hands-OnWorkshop
This tabletop system is used in industry because it’s cheap and fast.
Sampling: Test several times over the year to see seasonal changes and to see whether readings include background from the reagents. Every once in a while, do the test on ultra-pure water. In winter, contaminant levels should go down because more water is added to the well.
In chemistry you’re always saying, “if it’s really there.” You always want to rest and retest.
Collection Bottles: A laboratory grade plastic bottle helps keep chemicals in the samples from sticking to the sides of the bottles. To collect a sample, fill it and dump it out twice and use the third fill. Store in a cool, dark place and test within 48 hours. Surface water should be filtered to remove particles and bacteria which might change water chemistry.
Tricorder: It’s a spectrophotometer which shoots three wavelengths of light across a sample, based on the substance you’re testing for. It will do all the calculations for you. You test an unreacted sample (the “blank”) first, then the reacted sample. Readouts will be to two decimal places, in ppm.
Cuvette: A little container used by the spectrophotometer made from optically clear glass that’s machined to have even wall thickness. Fingerprints can contaminate it, so use chem-wipes, pick the cuvette up by the lid or above the shoulder, and keep the inside uncontaminated.
There is a whole language of mixing reagents; swirl, flick, invert, and shake. In these procedures we invert most of the time.
Lab Timer: It has a minute, an hour, and a stop button. Pushing the two top buttons simultaneously zeros it. A big button resets it.
Cleanup: Clean up with hyper-clean HCl. 30% HCl can burn flesh but ours is at 15%. It separates things that have bonded to the cuvette glass and burns them off. Pour about 1/4 inch in the cuvette, screw the lid on, slosh it around, pour into the drain, then do the same, twice, with ultra-pure water. Store upside-down on Kimwipes until dry.
The reactive liquid is toxic waste and is poured into a canning jar with absorbent material (a starch polymer or vermiculite).
Procedure:
Try to run your test exactly the same way every time, so that your errors will be systematic. Test and re-test.
Russel lined up five cuvettes on a piece of paper and labeled the paper: blank, phosphates (PO3), surfactants (LAS), phenols (ph), Copper (Cu), Chloride (Cl).
Russel operated the meter, Madrona wore latex gloves and prepared the samples.
We started with a sample from LG’s 42 foot well, which had particles at the bottom. Madrona put a sterile syringe filter into her syringe, then drew out 60 ml.
She squirted 10cc (a cc and a ml are the same) into a cuvette, marked by the line at the shoulder. This is the blank.
On the tricorder, there are buttons for on, off, exit (to go back in the procedure), up and down scrolling, and enter. To start, press enter. Go to testing, use the scroll bar to find the folder called Sequence 1.
Inside that folder, start with PO4, phosphates, low level. It asks “scan the blank.”. Wipe the cuvette, put it into the well, cover it, press enter. Flash indicates “blank done.” Now scan the sample.
To test for phosphates, mix 10 ml sample with 1 ml acid reagent. Use a 1 ml dropper to extract the reagent. Don’t stick the dropper into the sample tube to prevent contamination. Then, add .1 gm of phosphate reducing agent, which comes with a little spoon. Cap and shake (this may take a long time) until all reagents dissolve, then set the laboratory timer for 5 minutes. Some of the reactions are held together with weak atomic bonds and fall apart in 3 or 4 minutes.
You can reset by reshooting the blank any time; press exit.
When the timer went off, the PO4 cuvette was immediately inserted. The reading was .16 ppm. After 15 seconds or so, he shot it again and again got .16, so it didn’t change. You’d see 1 – 10 ppm in a goose pond. At 1 ppm it starts to be of concern.
The copper test is very fast. Scroll down to Cu for copper,. Enter. When asked, shoot the blank.
Add 5 drops of the copper mix to the next sample cuvette, invert it two or three times, then scan immediately. In our case, it was .01 ppm, which is at the low end of what it can measure, so perhaps it is not even there at all.
The next test was for surfactants, the MBAS test or LES test. One of the reagents, the indicator, is dissolved in toluene, an organic, carcinogenic solvent. Don’t sniff it, don’t spill it. It’s volatile. In case of a spill, it’s not water soluble so absorb it with soap or better, alcohol. The thing that will get it off you fastest is alcohol.
Madrona mixed in a pH buffer (sodium bicarbonate), then ultra-pure salt. She added 2 ml of toluene/methelyne blue solution, shook it for about a minute, then let it sit for five minutes. We end up with an aqueous layer (the sample) and an blue oil or organic layer, (the toluene), floating on top. The salt pushed the methylene blue out of the toluene into the water. Russel flicked the side a few times during the wait to help the solution unstick from the sides of the glass.
After 5 minutes the sample went in the spectrometer and read 1.2 ppm.
To test for phenols, first shoot a blank. Then, add a buffer, then a reagent and an activator to the sample.
The indicator looks yellow and turns green and purple if there’s more than 1 ppm. Sediment samples from bay bottoms turns to india ink in seconds. The sample was inverted a few times and then scanned. The reading was 00, no measurable phenols, below the LOD – limit of device. Our LOD is around .1
To test for chlorides, break up the tablet with a pill crusher. Add the sample, invert two times (it will be cloudy) wait 2 minutes, shoot the blank and then shoot the sample. This is the argentometric method, Silver Nitrate. Nitrogen and Chlorine compete for the affection of the silver. The silver looks around for any chloride that’s in there and will switch ionic partners, which changes the wavelength of absorption in the solution.
This one came out to 19.7 ppm, which would be salt, MgCl (from limestone), or KCl. Anything over about 5 ppm is an indication that something is there, either geological or saltwater intrusion.
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