group 6 dissolved oxygen determination ppt
TRANSCRIPT
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Group 6
Gochoco, John Benjamin B.
Marcelino, April Adrienne G.
Posadas, Grace Catherine A.
Uy, Augustine Leonard G.
Valencia, Vivienne G.
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Dissolved Oxygen (DO)-concentration of oxygen dissolved in water -expressed in mg/l or as percent saturation
DO Analysis-measures the amount of gaseous oxygen (O2) dissolved in an aqueous solution
INTRODUCTION
Winkler Method- technique used to measure dissolved oxygen in freshwater systems
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Saltwater
Freshwater
Saltwater - watercontaining a largeamount of salt; orit is the body ofwater which hasover 1,000 ppm(mg/L) totaldissolved solids
Freshwater -situated in a remoteor obscure area;provincial; waterwith less than 500parts per million(ppm) of dissolvedsalts
Estuary - body ofwater formed wherefreshwater fromrivers and streamsflows into the ocean, mixing with theseawater.
Objectives1. To be able to determine the amount of
dissolved oxygen in an aquatic environment
2. To compare and contrast the measured dissolved oxygen obtained using the Winkler Method against the 5 different
sites.
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METHODOLOGY
Materials:
• 300.0 ml BOD bottles or SOLA (glass) bottles with cap
• 250.0 ml graduated cylinder
• 500.0 ml Erlenmeyer flasks
•1.0 ml Pipettes
•Rubber aspirator
•Titration set-up
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Field Sampling Procedure:
Collect samples in a 300 mL SOLA bottle
Add 2ml of manganous sulfate solution
Add 2 ml of alkaline-iodide-sodium azide solution
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Shake the bottle by inverting several times
Add 2ml of conc. sulfuric acid
Allow solution to settle
Shake well until precipitate is dissolved
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Titration Procedure:
Pour 200ml of sample from the SOLA bottle into an Erlenmeyer flask
If the solution is reddish-brown in color, titrate with 0.0250 N sodium
thiosulfate
If the solution has no reddish-brown
color, or is only slightly colored,
add a small quantity (approx. 1 mL) of starch indicator.
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RESULTS AND DISCUSSION
Figure 1. D.O. in Balingasay River
4.5
6.8
3.9
10.7 10.7
0
2
4
6
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10
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Site A Site B Site C Site D Site EAm
ou
nt
of
dis
solv
ed
Ox
yge
nSeries 1
Series 1
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Oxygen gets into the water when:
• Oxygen from the atmosphere dissolves and mixes into the water’s surface
• Algae and bay grasses release oxygen during photosynthesis
• Water flows into the Bay from streams, rivers and the ocean. Ocean waters generally have more oxygen. River waters are fast-moving, which helps oxygen from the air mix in.
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Factors affecting D.O. in water• High temperatures• Nutrient pollution• Flow of water
Dissolved oxygen profile of a river downstream of a discharge (Snape et al., 1995).
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CONCLUSION
• Different factors affect the dissolved oxygen in thewater such as temperature, various chemicalreaction, and aquatic animals.• There are variations on the amount of dissolvedoxygen for the 5 sites and based from the results, site Ehas the highest amount of dissolved oxygen and site 3has the lowest amount of dissolved oxygen.