Let's have a look at the column that has been exposed to light.
We can perfectly tell apart the side of the bottle that has been exposed to sunlight from the one that has not.
In the lower region, a blackish colour can be seen due to the precipitation of iron sulphide (product of iron oxidation in the presence of hydrogen sulphide coming from the CaSO4.
Halfway up, in the area exposed to light, aerobic microorganisms have not had enough time to fully develop. However, at the top are what appear to be small green algae. They grow in this area because they have sunlight and oxygen at their disposal. But, they are not yet prepared to grow in intermediate zone due to hydrogen sulphide.
Meanwhile, the column that has not been exposed to light at all...
The Rio San Pedro sediment lies now at the bottom of the column and in the superior part of the column, there is approximately two inches of water. The bottom has a darker colour than the rest of the bottle. This is due to the presence of iron sulphide that comes from the activity of anoxygenic bacteria. The middle part of the column has a grey color with black dots.
On the part at the top of the column (let's remind that this part is just water) we can distinguish traces of iron oxyde, which possess a copper-bright orange colour. The reason that this compound appears is that some oxygen can penetrate through the bottle's plastic.
Stay tuned for more on our columns!
Photos please!!!
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