The document summarizes water chemistry data from multiple sites collected in 2014-2015. Key findings include: - Temperature, salinity, and density varied between sites, with the Scheldt River, Cenflumarin dock, and pond being brackish. - Hardness, pH, and nutrient levels differed depending on a site's geology, nutrient inputs, and biological activity. Agricultural sites tended to have higher nitrates. - Values at the Cenflumarin dock changed significantly from 2014 to 2015 after its connecting lock was reopened. - The data helps understand each site's water chemistry in relation to surrounding land use and biological and environmental factors.

1. Water chemistry
Cenflumarin – 4MT 2015
Teacher: Nathalie Verelst

2. Water chemistry partners

3. Water chemistry sampling sites

4. Methodology
• First we compare our data to last years data of
measurements around the school.
• Then we compare our test strip data to the
Walhorn, Emajõgi, Lake Melliste and Luutsna
datasets.
• We try to identify the land use around the
water body to explain the values.

5. T, S, ρ
• 2015 is warmer than
2014
• If S↑ → ρ ↑
• Measurement of S in the
Scheldt river might have
been less accurate.
• The dock is a lot less
saline, but it had rained a
lot before the
measurement.
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Scheldt Pond Dock
T in °C 2014 T in °C 2015
S in PSU 2014 S in PSU 2015
Density in mg/cm³ 2014 Density in mg/cm³ 2015

6. pH, GH, KH
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Scheldt Pond Dock
pH strips pH titration GH strips KH strips KH titration
• pH (titration) is slightly alkaline than
the pond or the dock. This is
because the Scheldt is more saline.
• KH is the same
• GH is higher in the pond and dock
because water is not moving, i.e.
there is more uptake of CO2 at the
surface.
• Titration is the most accurate type
of testing
• In comparison to 2014, the water
has become a lot harder, it can now
more easily bind with an acid an this
will lower pH (see also the graph on
the next slide).

7. CO2 & O2
• Before the water was
more alkaline, though it
contained a lot more CO2.
• With the rise of
temperature, primary
production consumed a lot
of CO2 and a bit of O2 .
• The dock became less
alkaline because of mixing
with the Scheldt river.
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Scheldt Pond Dock
02 in mg/l 2014 O2 in mg/l 2015 CO2 in mg/l 2014
CO2 in mg/l 2015 KH in °d 2014 KH in °d 2015
pH 2014 pH 2015

8. NO3, NO2 & NH4
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10
15
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Scheldt pond dock
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25
9
NO3 2014 titration NO3 2015 titration NO3 2015 strips
NO2 2014 titration NO2 2015 titration NO2 2015 strips
NH4 2014 titration NH4 2015 titration
• In 2015 we have less
ammonia in the Scheldt,
pond & dock.
• In 2015 chemical oxidation
of NO3 into NO2 was more
pronounced in the Scheldt
river.
• The amonium level clearly
dropped in 2015. This might
indicate a population of
decomposers in anaerobic
circumstances in the
benthos.

9. PO4
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
Scheldt river Middlepond Dock
2014 2015
• There has been an
increase of PO4 between
2014 & 2015. This
increase is more
pronounced in the dock
and pond because
circulation is low. The
dock & pond are also
connected. The most
likely source of PO4 is the
increase of nutrient load
in the Scheldt river.

10. Copper
• In 2014 the lock was
permanently closed
and the water stayed
on the same place
and there was a lot of
oil pollution. Recently
the lock has been
repaired and all
values are just within
normative values
(norm = 0.1 mg/l).
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0.02
0.04
0.06
0.08
0.1
0.12
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0.18
0.2
Scheldt river Middlepond Dock
Cu_2014
Cu_2015

11. T, S, ρ
• Conductivity measurements
at respective temperatures
were converted to psu.
• The Scheldt river,
Cenflumarin dock and pond
are brackish. If S↑ → ρ ↑
• Temperatures in Lake
Melliste and Luutsna river
are lower.
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30
T in °C S in PSU Density in mg/cm³

12. pH, GH, KH
• Salty water is more alkaline than
fresh water.
• Orissaare has low hardness and
pH. The water will not easily bond
to an acid.
• The hardest water is found in
rivers that flow through mineral
rich geological regions.
• Cenflumarin pond has a relatively
high nutrient content and low
uptakem the water will therefore
be more likely to bond to an acid.
• Luutsna river has unusually low
carbonate hardness.
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3
8
13
18
23
pH GH KH

13. NO3, NO2, NH4
• Nitrates are higher in
agricultural zones and in rivers
that flow through agricultural
zones.
• When it becomes warmer
they form toxic nitrites.
Titration of nitrites led to a
false positive in the Scheldt
river (NO2 high, T low), what
about Emajõgi river?
• Decomposers can break down
poisionous nitrites into NH4,
though their productivity is
low. NH4 was not measured in
Estonia.
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50
NO3
NO2
NH4

14. Conclusion
• It would be interesting if all partners could have measured
temperature, salinity, O2 and CO2 – content.
• The values in the Cenflumarin dock changed significantly from
2014 untill 2015 because the lock connecting the dock to the
Scheldt river has been reopened.
• The Walhorn sites suffer from a high nutrient load from
agriculture, for Emajogi river we should consider not only the
nutrient load, but also the temperature. In cold conditions,
there will be no nutrient uptake.
• We were wondering whether the high nitrite value for nitrites
in Emajõgi river was not a false positive, since no nitrates are
present. Lake Melliste seems a rather clean water body.