A. How much mercury a 45 lb (pound) child would ingest by eating one 6 ounce of white tuna per week?
B. How many times more compare to the EPA's reference dose?
Ans:
Step 1:Determine EPA’s recommended standard for a 45 pound child (Multiply child's body weight by EPA's reference dose.)
· Convert 45 pounds to kilograms = 20.45 kilograms
· 20.45 kilograms x .1 micrograms per kilogram per day
· EPA recommended level = 2.05 micrograms per day = 14.35 micrograms per week.
Step 2 ; How much mercury is in 6 ounc of white tuna?
· Convert 6 ounces to grams = 170 grams X .31 ppm (or micrograms per gram)**
· Mercury ingested = 52.7 micrograms per gram (A)
Step 3 – Compare amount ingested with EPA’s recommended
· Divide 52.7 micrograms by 14.35 micrograms = 3.7
Conclusion: By eating 6 ounces of white tuna a week, the child is ingesting almost 4 times EPA’s recommended dose (B)
Question 2
A. How much ppm of mercury does the dolphin (Taiji, Japan) contains?
B. And what harmful health impact does it cause to us? (Name the impacts done to child and adult)
Ans:
A) 2000ppm
B) Methylmercury generally cause nervous system damage.
For fetuses, infants, and children, the primary health effect of methylmercury is impaired neurological development.
Impact of methylmercury poisoning on adult may include; impairment of the peripheral vision; disturbances in sensations ("pins and needles" feelings, usually in the hands, feet, and around the mouth); lack of coordination of movements; impairment of speech, hearing, walking; and muscle weakness.
QUESTION 3 (15 MARKS)
A. What instrumental methods are used determine the samples for lake monitoring?(Name 2)
B. What are the differences between AAS and CVAAS? (Name 3)
Ans:
A) LA-254 LabAnalyzer & PA2 water analyser
B) Differences:
1. Divalent mercury in aqueous samples was reduced to HG by strong reducing agent in acidic condition (E.g. stannous chloride). Different form sample preparation of digestion are used to digest different kind of mercury so that it could obtain best sensitivity
Preparation by “potassium permanganate perchloric acid, nitric acid, sulphuric acid and sodium hydroxide and lastly sodium borohydrie”
2. Does not need to employ flame technique as mercury could exist at free ground state
3. Sample must be Teflon cap at all times; mercury is a highly volatile metal and could escape and affect the accuracy of the experiment