back to index ofchapters1. What is seawater quality?
Ans. Seawater quality is a measure of the ability of water to supportmarine life and maintain public health.
2. How should the temperature of a water sample be read?
Ans. The best way to measure sea temperature is to put a thermometerin the water for about 30 seconds and then read it while it is in the water
3. What is turbidity and how is it measured in the sea?
Ans. Turbidity is a measure of how dirty the water is. Turbidity is causedby soil running off the land.
A turbidity tube is used to measure turbidity in shallow water.
To measure turbidity in deeper waters, use a secchi disc made from acord marked at metre intervals, an ice-cream container lid and a brick.
4. What is a possible source for mercury pollution in estuaries?
Ans. From the waste of paper mills
5. What is the average range of pH in sea water?
Ans. Sea water tends to be slightly alkaline, ranging between pH 7.8 8.4
6. What happens when a pH instrument is calibrated?
Ans. Once the instrument is calibrated (placed in known pH solutionsbefore use and the readings matched), it can be placed in the seawater sampleand the reading taken from a digital display.
7. Which organisms can withstand a wide range of pH?
Ans. Bacteria
8. How are dissolved oxygen levels measured?
Ans. Take a sample of sea water using a dissolved oxygen bottle as shownin Figure 232.3. Chemicals are added to convert the dissolved oxygen gasin the water into a solid form which can be tested with a chemical solutioncalled sodium thiosulphate. The sodium thiosulphate is then added drop bydrop until a colour change occurs. The number of drops are then recordedbecause this is a measure of the oxygen levels in parts per million.
9. What is the average dissolved oxygen level for sea water?
Ans. In sea water, the average amount of oxygen is 7 ppm which showsthat marine life has been able to survive on a very small amount .
10. Below what dissolved oxygen level do fish die?
Ans. The balance of dissolved oxygen in sea water is delicate and ifthere are too many plants (as during an algal bloom) the oxygen made duringthe day can quickly be used up at night and drop to below 4 ppm. At thislevel most fish will die.
11. What is the name of the system that carries wastewater from our homes?
Ans. In urban areas, the wastes from our bodies, kitchens, laundriesand showers are connected to a sewerage system. In many places this seweragesystem is linked to a wastewater treatment plant which removes the harmfulwastes before discharging the water into the sea.
12. Above what level of bacterial counts per 100 mL is it dangerous toswim in sea water?
Ans. If there are more than 150 colonies per 100 mL of water sample,the water is not safe to swim in or take food from.
13. Name two nutrients that are delicately balanced in the sea.
Ans. The sea maintains a delicate balance of the nutrients nitrogen andphosphorous.
14. How can we use animals to test for water quality?
Ans. Checking for the presence of types of invertebrate animals can beused to determine water quality. This form of testing is more environmentallyfriendly that some of the ones described previously in this chapter becauseit does not use chemicals.
Using this method, collect animals with a net from a stream. Record whatinvertebrates you have caught and use these records to assess the qualityof the water.
The water invertebrates are classified into four different groups dependingon how sensitive they are to pollution. These groups are very sensitive,sensitive, tolerant and very tolerant.
Each water invertebrate is given a rating according to how sensitiveit is to pollution. Very sensitive animals are given high numbers and verytolerant animals low numbers.
Stonefly nymphs are very sensitive (Figure 234.2). Flatworms belong tothe very tolerant group (Figure 234.3). So the stonefly bug is given a ratingof 8 and the flatworm a rating of 3.
The more sensitive the animals found in a stream, the less polluted thewater quality is likely to be. To calculate the water quality of a stream,add the numbers to get a pollution index. Rate the stream according to theindex number you get.
If there were lots of very tolerant to pollution animals and no verysensitive to pollution animals, then the water quality would be poor.
Scientists from a programs called Streamwatch, WaterWatch and from CSIROhave developed the following pollution table:
Pollution index Stream quality rating
20 or less Poor
21 35 Fair
36 50 Good
51 or more Excellent
An example of how the scientists went about measuring water quality usingwater invertebrates is as follows:
Very sensitive Sensitive Tolerant Very tolerant
Yabbies (7) Dragon flies (6) Leech (3) Mosquito (1)
May flies (7) Mussels (6) Beetles (5) Bloodworm (1)
Shrimp (6) Snails (3)
Totals (14) + (18) + (11) + (2)
Pollution index = 45 (Stream quality rating = good)
15. Make a list of any three good water quality parameters.
Ans The parameters for good and bad seawater quality depend on localareas and conditions. Over time, animals and plants adapt to their particularenvironment. The list of parameters for poor quality listed below are onlygeneralisations.
· Temperature big differences in degrees in place andtime (say 10 degrees)
· Dissolved oxygen less than 60 per cent saturationand fish gasping for air or not present
· Turbidity one week turbid, the next clear
· Nitrate levels greater than 0.01 ppm
· Phosphate levels greater than 0.01 ppm and algalblooms occurring
· Bacterial levels greater than 150 colonies/100 mL andsigns warning swimmers not to bathe in place
· Biodiversity would have changed. Old timers wouldtell stories of the abundance of animal and plant life in the past but currentscientists would report of few species today
· Riparian vegetation non-existent. Polluted stormwaterflows into rivers and streams and there are few or no trees or mangrovesbeside creeks, rivers or estuaries.
1. Join a Streamwatch, Ribbons of Blue or Waterwatch program in yourstate. Locate your state coordinator and find out who your local representativeis. Become involved in monitoring your local creek or estuary.
Suggestions:
Lists of addresses can be obtained form the waterwatch home page.
http://kaos.erin.gov.au/portfolio/anca/waterwatch/waterwatch.html
For the manual dial up:
http://kaos.erin.gov.au/portfolio/anca/waterwatch/waterwatch.html
2. Make a newspaper scrapbook collection of articles involving waterquality. Identify which of the issues are important and write a paragraphon each.
Suggestions:
Use newspaper folder
3. Obtain some water testing equipment and study your aquarium over aweek for the following parameters:
· dissolved oxygen
See: http://www.vic.waterwatch.aus.net/manual/sect4b.htm
· temperature
· turbidity
· nitrogen as nitrates
· phosphorous
· pH
· salinity
Make notes and draw a graph of the changes.
4. Type the word 'waterwatch' into your computer's search engine andlocate information on water quality monitoring.
http://www.dse.unsw.edu.au/water/stream.html
1. stormwater
2. riparian
3. turbidity
4. alkaline
5. pH
6. urban
7. sewerage
8. nitrogen
9. phosphorous
10. DDT
11. malaria
12. invertebrate
13. environmentally friendly
14. chemicals