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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.
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.
Escherichia Coli
green expresses the bacteria
100 ml of sea water
in
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.
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.
THANKS FOR WATCHING