Lab Exam Flashcards
What is the Canadian drinking water guideline maximum for Total Dissolved solids?
500mg/L
Bottled “mineral water” usually exceeds ____mg/L of TDS
500mg/L
Tapwaters with high TDS cause what problems?
Undesirable tastes, form deposits on pipes/fixtures, may cause gastrointestinal problems and kidney strain
If high TDS is due to calcium and magnesium minerals, the water is referred to as ____
hard
What are benefits of hard drinking waters?
Have reduced heavy metal toxicity and are a good source of dietary calcium
What is the hard, but most accurate way of estimating TDS?
Filter a known volume of water into a preweighed container, evaporate the water, weight the residue
What is the easy and most common way to estimate TDS? What is the benefit of this?
Using an electronic probe. It is helpful because it can be performed on site
If Total Suspended Solids (including small particles like viruses) must be measured, how can one do this?
Specialized micropore filters must be used, but only if the residue does not exceed 200mg. Residue is dried out at 100 degrees C
Waters with a lot of suspended solids come from what situations?
Where there is a great deal of turbulence or where effluent is discharged into the water body
What precautions must one take when collecting a water sample for suspended solids analysis?
Must be low enough that floating matter is avoided but high enough that there is no contamination with bottom sediment
Where are there high saline groundwaters in MB?
Southwestern MB
Precambrian shield waters contain ____ amounts of chloride
low low low
If Precambrian shield waters have chloride present, what does that indicate?
Contamination from human activity (ex. salt on roadways, effluents)
The Canadian drinking water guideline for chloride is ____mg/L
250mg/L
Chloride concentration is usually associated with a salty taste. Is this always the case?
No, as the salty taste comes from the major cations being sodium. Sometimes they are instead calcium or magnesium, and the salty taste is not detected.
What are some nitrogen and phosphorous sources in human sewage
Body wastes, dish soaps, phosphate/ammonia cleaners, household products, garburators, industrial effluents, lawn/garden fertilizers, municipal tapwater treatment plants, pet waste, illegal chemical disposal
Why does the city of winnipeg deliberately add phosphorous to our pipes?
To reduce leaching of lead from pipes downtown
What do urban sewage treatment plants consist of?
We have lagoons where the sewage sits until we decided to treat it for ONLY PHOSPHOROUS
What is the most commonly used method of chloride detection in water samples? What does this involve?
Argentometric method. This involves the titration of chloride with silver nitrate. This forms a red precipitate (potassium chromate is used to indicate end point)
What do community sewage lagoons consist of?
Large lagoons where waste is eventually released into the river or stream
What do rural (farm) residents do with their wastes?
Have a septic field. BAsically there is a large tank underground where the crap settles out, and septic pump brings liquids to the surface into the field. Over time this can create “ponding” of the liquid sewage
Cottage residents have _____ to hold their waste
Holding tanks
In-non potable waters, some substances are present in high enough concentrations to interfere with argentometric chloride detection. What are some of these substances?
Bromide, iodid, cyanide, orthophosphate in high concentrations (precipitates some silver), iron in high concentrations (interferes with end point detection)
Analysts prefer the _____ method of chloride quantification because the end point is more obvious
Mercuric nitrate method
Describe the potentiometric method of chloride quantification
Used when samples are highly coloured/turbid. A silver electrode is used to measure changes in potential difference as silver nitrate is added
What is the formula for chloride concentration?
mg chloride/L = (A-B) x N x 35450/mL sample
A = mL silver nitrate added to produce end point in sample B = mL silver nitrate added to produce end point in blank N = normality of silver nitrate (0.0141 N)
By what formula can NaCl be estimated?
mg NaCl/L = (mg chloride/L) x 1.65
Briefly describe the in-water nitrogen cycle
Ammonia is converted to nitrite in the presence of oxygen, which is in turn oxidized to nitrate.
Ammonia and nitrate may attain higher levels in _____ waters and ____ waters
Ground waters and polluted waters
What happens when water containing ammonia is chlorinated?
Chlorine reacts with ammonia to produce carcinogenic mono and dichloramines
The Canadian drinking water guideline for nitrate is _____mg/L nitrate or _____ mg/L Nitrate-N
45mg/L, 10mg/L
Nitrate toxicity results in water symptoms?
Gastric and prostate cancer, non-Hodgkin’s lymphoma, spontaneous abortion, affects on human behaviour
What is the primary concern with nitrite in groundwater?
There is almost no O2 in groundwater so nitrite cannot be converted to nitrate. This may lead to Methemoglobinemia: Blood vessels dilate, oxygen supply to brain/extremities reduced. Hemoglobin is converted to methemoglobin and blue skin, lips, nails (cyanosis) can occur. May lead to “blue baby disease”.
What kind of water guidelines are there for ammonia in Canada?
No drinking water guideline for ammonia, though there is a maximum set out for “aquatic life”
____ and ____ are used to extract gold in Manitoba
Arsenic, cyanide
Waters with low organic content can be analyzed for nitrate using what method?
UV spectrophotometric method
What is another common method for analyzing Nitrate concentrations?
Selective sensor which develops electric potential difference across membrane
What happens to waters that have undergone “reverse osmosis”?
Reduces stuff inside the water by about 90%
What is the problem with distilled drinking water?
Water molecules are not attached to anything and therefore attacks anything they can
are water bottle distribution companies required to provide chemical analysis?
No, it is voluntary
What is the International Bottled Water Association?
A board in Virginia that mostly serves to yell at people who say bottled water is bad
What does it mean to say a water is distilled?
HAs been vaporized and condensed, all the minerals have been removed
What does it mean to say a water is “purified”?
Processed in some way to remove some of the minerals, most often by reverse osmosis
What does it mean to say something is “mineral water”?
Natural water that has a lot of dissolved minerals in it (therefore more flavour). Includes hard water
The classification for mineral water is ____mg/L TSS
500mg/L
What does it mean to say water is “natural”?
Untreated.
What does it mean to say something is “spring water”
Comes from an artesian well
What does it mean to say that something is “bottled drinking water”
IT’s literally just tap water put in a bottle
What does it mean to say something is “sparkling water”?
Carbonated (naturally or not)
What does it mean to say water is “mineralized”
Minerals were artificially added (after being removed somehow)
How does one determine whetehr a bottled water brand has been decontaminated in some way?
Must be either ozonated or carbonated (bacteria and fungi can grow otherwise)
What is an ideal maximum for mineral content in water
300mg/L
Why is it important to worry about heavy metal contamination in bottled water?
Concentrations on bottled water are listed in ppm when in fact standards for these things are in ppb, so obviously it will always show up as “0” after rounding - totally unsafe. Therefore you can exceed guidelines and still be labelled as 0ppm
Generally the best bottled water source is what?
Water valley, Alberta
Why is it important to have expiry dates on water?
Because you have no idea how long it has been on the shelf (how long the plastic/glass/packaging has been leaching into the water)
What packaging is it best to avoid when buying bottled water and why?
Coloured bottles - because they may contain lead or uranium
Glass bottles - often have additives like lead, boron, cobalt
Plastic bottles - often leach metal stabilizers, plasticizers, breakdown products (ex. vinyl chloride) and styrene substances
Which is generally better for health, domestic or international/imported water?
domestic. International usually sucks
Where can radioactivity come from in MB surface waters? What radioactive compounds are present?
Usually from substances in Precambrian Shield rock but also comes from nuclear reactor coolant, nuclear weapons/reactor accidents, wastewater from labs/universities - includes radium (radon gas), uranium, thorium
Radionuclides of ____ atomic weight may bioaccumulate in living tissues
HIGH
When analyzing the level of nitrates in a sample, what UVwavelenths are used?
220nm subtracted by 275nm
What was used in the lab to examine radioactivity of samples? What types of radiation does it analyze?
RM-60 Radiation counter. Suitable for broad spectrum monitoring of alpha, beta, gamma, and X-rays
What are alpha radiation particles?
Positively charged helium nuclei emitted at high speeds. They can be stopped by air and do not travel far but can do damage to living tissue.
How does one determine if radiation emissions are alpha?
Put a sheet of paper over the sample and monitor for a drop in radiation
What are beta radiation particles?
Electrons originating at very high speeds from the nucleus of radioactive elements. Smaller than alpha particles (less ionizing power)
What does it mean if radiation particles are smaller?
Can penetrate deeper into tissues
What are gamma rays?
High energy electromagnetic radiation (photons) - not particles. Penetrate better than X-rays, and can damage tissue (can ionize DNA).
Once radiation was measured in the lab, what calculations were performed? What do the results then reflect?
We corrected for the background radiation. Results reflect levels comparative to the background, not total radiation.
How would one study total radiation of a water sample?
Run sample through charcoal filter, the total radiation on the filter reflects total ration in the unit volume
Why are coliform counts in water important?
Often they are the only routinely monitored parameter - influencing safety of both ingestion and skin contact with water.