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Results of chemical analyses at 

Lagoa Azul (& Lagoa Verde), Sao Miguel (Azores/Portugal)

The chemical results of all 5 eco systems in detail:

Italy Spain Germany Hungary Azores

Click here to compare the Azorean results with the spring results of the 4 other TAPAS eco systems

Click on this picture to see a map of this volcanic double lake system

Lagoa Verde (front) and Lagoa Azul (behind)

Date of measurements: Oct  01 Oct 01 Feb 02 Feb 02 Apr 02 Apr 02 Dez 02 Dez 02 Apr 03 Apr 03 Jul 03 Jul 03 Nov 03 Nov 03
Name of Measurement point (Click on the map below to locate these points) A1: Lagoa Azul V1: Lagoa Verde A1: Lagoa Azul V1: Lagoa Verde A1: Lagoa Azul V1: Lagoa Verde A1: Lagoa Azul V1: Lagoa Verde A1: Lagoa Azul V1: Lagoa Verde A1: Lagoa Azul V1: Lagoa Verde A1: Lagoa Azul V1: Lagoa Verde
pH 6 6,5 6 6,5 6 6,5 9 7,6 8,2 9,13 9,22 9,67 8,25 8,03
Water temperature °C 18,5 18,5 12,5 13 12,5 12,5 13,3 15,2 16,8 16,5 25,5 24,6 15,8 15,3
Solved Oxygen mg/l 9,5 9,4 11,2 12,4 15,8 12,8 12,7 12,2 9,9 11,9 9,4 11 8,8 11,5
Phosphates mg/l 1,45 0,15 0,66 0,2 0,7 0,24 0,26 0,3     0,6 0,73 2,75 1,74
Nitrate mg/l 8 7 6,4 7,5 5,1 2,8 4,3 5,3 7,3 8,2 2,9 3,5 9,9 5
Nitrite mg/l 0,003 0,04 0,025 0,019 0,023 0,018 0,014 0,01     0,029 0,018 0,034 0,045
Phosphorus Pentoxide mg/l 0,49 0,11 0,49 0,15 0,52 0,18 0,19 0,23     0,45 0,54 2,06 1,3
Transparency   1 2 6 4 4 4 3 15 10 11,8 15 6 10 0
The pH-Value shows us how acid or basic the water is. Drinking water or water of clean eco systems has a pH-Value between 6,5 and 7,5 (almost neutral). All animals and plants living in a water eco system are well adapted for the pH-conditions in their surrounding. If the pH-Value changes, the water animals will become ill, can‘t breed or will die. Acid or basic substances come into water eco systems through household and industrial pollution or through acid rain The Solved-Oxygen-Value (O2) depends on the water temperature. If you have a higher temperature you will measure a lower Oxygen-Value. The value is also low if the water contents lots of dead organic material (e.g. dead animals, dead plants an algae, excrements…). The water quality falls. Healthy water eco systems have an Oxygen-value of 8-10 mg/l.
Phosphates (PO43-) are an important part of fertilisers, washing powder, food, excrements …). They are responsible for the eutrophication of water eco systems. The plant overgrowth there (caused by too much phosphates brought by rain and sewages) results in putrefaction and later in too less solved Oxygen. Life in the water system is going to be killed. The EU standard value for water is 0,56 mg/l. Temporary a maximum of 6,95 mg/l is allowed. Nitrate (NO3) isn’t directly poisonous. You can find it all over the nature and in lots of bio-chemical cycles. Plants need it for growing. The problem is that Nitrate can be changed into the dangerous Nitrite. Nitrate reaches water eco systems through rain water, that flushes it from fertilised fields away. It also reaches the water eco systems through purification plants and exhaust emissions (cars and lorries). In water eco systems with too much Nitrate there will be often a proliferation of algae.
Nitrite (NO2-) is very poisonous. Only 2 g can be very dangerous for a man. It cuts off the supply with Oxygen in the blood of animals or humans. Fish will die if the water contents too much of it. Enzymes in bacteria and fungi are responsible for the change from Nitrate to Nitrite (Nitrate reduction). Also Nitrite is the starting substance for carcinogenic substances (Nitrosamine). More than 0,2 mg/l Nitrite in Water means: The water is very contaminated. Water eco systems of a very good quality have a value of less than 0,01 mg/l. Nitrite is part of lots of salted food. That’s why you shouldn’t eat too much salted sausage.
 
 

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