Analysis

ANALYSIS We collected samples of sea water in the Niskin bottles. Then the samples were put in a coolbag.  

We checked temperature and pH of the water samples directly on the site. Right parameters of temperature and pH are essential to life. To check the temperature we use a thermometer To check pH we used a portable pH-meter

The samples collected during the Coastwatch inspection were analised in Laboratorio Genovese and in the Chemistry lab in our school. In Laboratorio Genovese we looked for Bacteria and heavy metals.

Bacteria We looked for Escherichia Coli and enterococci in our sea water. We analized three samples of water. There is a law in Italy which controls the concentration of these particular bacteria in the sea and allows people to swim only if these criteria are respected: the limit for the Escherichia Coli is 500 units/100 ml max and for the Enterococci it’s 200 units/ 100 ml max. Escherichia Coli Streptococci

Step 1: The samples were given a number and were registered. A colture ground is put in the petri dish. Bacteria have to find the suitable conditions to grow.

Step 2: first the environment of the experiment was sterilized using a blowtorch 100 ml of each sample were filtered on a white membrane to separate and differentiate selective bacteria Then the membranes were put in petri dishes.

Step 3: the petri dishes were incubated. The petri containing Escherichia Coli at the temperature of 44⁰C The petri containing Enterococci at the temperature of 37°C.

Results The results should appear after 24 hours (for the Escherichia Coli) and after 48 hours (for the Enterococci). Colonies can be seen as they grow dark pink or red (Enterococci) or blue and green (Escherichia Coli) and they can be counted.

After 48 hours…

green expresses the bacteria in 100 ml of sea water We have Escherichia Coli green expresses the bacteria in 100 ml of sea water Enterococci dark pink expresses the bacteria in 100 ml of sea water

In the Tirrenian Sea, from Bastione to Spinesante, the level of bacteria during the Coastwatch Inspection, was under the limit, so water was clean enough for swimming. Conclusion

Analysis in the school lab In the school lab we analised the sea water samples testing hardness, the quantity of dissolved oxygen, nitrates, nitrites, sulphites and phosphates. Hardness expresses the quantity of alkaline salts dissolved in water. The solution changes from colourless through purple to blue solution.

Dissolved oxygen In water dissolved oxygen is essential to the growth and development of aquatic life. The common use of water must contain at least 2 mg/L of oxygen up to a maximum of 10 mg/L. When determining dissolved oxygen through iodometric titration the solution changes from colorless through yellow, blue to colorless.

Nitrites Nitrites represent the intermediate stage of the oxidation of nitrogen and typically originate from the oxidation of ammonia. The determination of nitrites is carried out by colorimetric method with chromoprotic acid: this organic acid colors solution pink.

Nitrates Nitrates represent the state of maximum oxidation. The presence of nitrates in water can originate both natural and man-made. The determination of nitrates is carried out by colorimetric method with sodium salicylate that colors solution yellow

PHOSPHATES The presence of phosphorus in surface water courses depends on domestic origin wastewater and fertilizers and pesticides. Phosphorus presence causes a phenomenon called “eutrophication”. The determination of phosphates is carried out by colorimetric method with ammonium molybdate: the solution colors blue.

SULPHITES Monitoring of sulphites is also important in environmental controls. In fact, the sulfite ions are toxic to plants and animals living in natural waters. The determination of sulphites is carried out by iodometric method: the solution colors blue.

HEAVY METAL Heavy metals are released into surface waters from chemical industries and by the use of fertilizers and pesticides in agriculture. Some heavy metals, such as copper and zinc, are potentially toxic, small quantities are indispensable for the development of living organisms, large quantities can poison the organisms. Other heavy metals are toxic. Among these the most dangerous are cadmium, chromium, lead and mercury. In the sea water we searched Zn 2+ , Cd2+, Pb2+, Cu2+

Chemical parameters registred: nitrites (<0,2 mg/L), nitrates (< 1mg/L), phosphates (<1mg/L), solphites are in low concentration as well as copper and cadmium, which are totally absent. We can’t find these metals dissolved in water because they precipitate to the bottom of the sea.

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