Water project: (Signe N, Belinda, Ditte og Karina)

 

We went on field trip to the area around the Hulemose Lake to take some water samples that we had to analyse in relation to our water project. Hulemose lies in Nyråd, which you can see on the map below. The area is in addition framed with a dot-and-dash line on the map of Southern Sealand further below.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


We took four water samples from Hulemose Lake, from the water coming to Hulemose Lake, from the surrounding fields, water from Kulsø that lies at the military training ground and from Blegen where the water comes from the Hulemose Creek and the Hulemose Lake.

 

Experiments for water project:

mg NO3-/l

Locality

1.

2.

Outflow Hulemose Lake

13,6

14,52

Inflow  from Kulsø

22,88

-

Inflow from fields

57,64

-

Hulemose Creek - Blegen

33,0

25,08

 

We used a Hach-box with a spectrophotometer to find the nitrate contents in the water samples we had taken. As the results show the nitrate contents were highest in the water sample from the water from the surrounding fields. The leaching of nutrient salts from the fertilising that happens causes this.

The sample taken at Blegen had the second highest content of nitrate. As the water from here mainly comes from areas where there is normally no fertilising, it is a bit peculiar that the nitrate contents were so high. With this sample we have probably made a mistake and thereby obtained a wrong result. Leaching from fields and the local soccer pitch could also have caused it.

The nitrate contents in the water from Kulsø were the second lowest. This is very likely as Kulsø lies at a military training ground, where there is no fertiliser.

As there is dilution of the water that comes from the surroundings into Hulemose Lake, the nitrate contents here were the lowest in the water we analysed.

 

 

Arrows have been drawn at the places where our water samples comes from.
 

 

 

Besides analysing the water samples we took in the area around the Hulemose Lake, we also analysed drinking water, we had brought from home, for nitrate. We also found the hardness of our drinking water.

 

 

If you look at our measurements of the nitrate contents in our drinking water, there are some big differences in the results. You can’t say that the nitrate contents are higher in a certain area, there is in this way no specific logic in the figures. All the figures are below the Danish permit limit at maximum 25 mg NO3-/l, so there shouldn’t be any particular health risk in this connection

 

 

 

Locality

mg NO3-/l

 

Locality

Total hardness

Permanent hardness

VUC

11,88 mg/l

 

Stege

24,9 °dH

15 °dH

Nyråd

7,48 mg/l

 

Præstø

18,7 °dH

- °dH

Stege

9,6 mg/l

 

Vordingborg

17,5 °dH

8 °dH

Nr. Alslev

9,68 mg/l

 

Vålse

31,5 °dH

20,5 °dH

Jungshoved

5,28 mg/l

 

Bogø

19 °dH

12 °dH

Skibinge

6,6 mg/l

 

Langebæk

23 °dH

13 °dH

Vordingborg

7,92 mg/l

 

Stege

24,3 °dH

14,2 °dH

Langebæk

6,16 mg/l

 

Langebæk

26,44 °dH

16,24 °dH

Præstø

6,16 mg/l

 

Jungshoved

 33,71 °dH

23,82 °dH

Svinø By

5,28 mg/l

 

Svinø

22,58 °dH

18,10 °dH

Ørslev

1,32 mg/l

 

Faksinge

 21,69 °dH

17,08 °dH

Vålse Vig

6,16 mg/l

 

Præstø

17,3 °dH

8,7 °dH

Allerslev

7,04 mg/l

 

 

 

 

Bogø

8,36 mg/l

 

 

 

 

 

Water’s hardness is caused by the contents of Ca2+-iones and Mg2+-iones. In Denmark you base the specification of water’s hardness on the idea that the hardness is entirely due to the contents of CaO. In the chart above the total and the permanent hardness is stated. The total hardness is measured from unboiled water. Permanent hardness is measured from boiled water as in this way some of the chalk has been removed from the water.

 

The definition on hardness is:

1 °dH (degree of hardness) corresponds to 10 mg CaO per litre of water.

 

Our measurements of the hardness degree on the drinking water we had brought along showed that the hardness was highest at the coasts, with the exception of one figure.

In Denmark there exists a lot of chalk in the underground and in Storstrøm’s County there exists especially much at the coasts, because you here find Møn’s Cliff, Stevn’s Cliff and Fakse Lime Stone Quarry, where the occurrence of chalk is big. This is a big contributory to that the chalk contents in the water can be reasonably high. People that live at the coasts have therefore often a bigger hardness in the water than people who don’t live at the coast. There exists quite e few local waterworks that makes their own drillings. This is also contributory to the variety in the hardness degree. In Denmark it is not unusual to have a so-called chalk magnet put up at the water supply to the house. This should be able to decrease the chalk contents in the water. Besides this there is of course some measurement uncertainty when you do the experiment that can give some variety in the figures that we have reached.