Iron Sheen
In some places in the peatland, the surface of the water shimmers in every colour. This is not an oil film, but iron sheen. This very thin layer consists of iron oxide and other mineral compounds. It forms as part of natural material cycles. Responsible for this are bacteria that oxidise iron and gain energy from the process.
1 – Clear Water
Iron sheen forms on clear, iron-rich waters.
2 – Iron Sheen or Oil Film?
Iron sheen is harmless to humans. To distinguish it from oil, dip a stick into the water. In iron sheen, the gap that forms remains visible; in an oil film, it closes again.
3 – Shimmering Colours
The thin layer shimmers like a rainbow. Iron oxide contributes the reddish hue.
4 – Ideal Conditions in the Peatland
A neutral pH value of 7 — neither acidic nor alkaline — and a low oxygen content are ideal for the formation of iron sheen. Iron-oxidising bacteria work best at a water temperature of 30°C.
5 – Iron-Oxidising Bacteria
As they break down iron compounds, iron-oxidising bacteria form yellow-brown strands that are highly conspicuous. On the bottom of iron-rich waters, they appear as an ochre-coloured slime.
Rotmoos
Iron oxide gives peatland pools and small rivulets a rusty red colour. The name Rotmoos, used for a peatland landscape, is derived from this.