Thursday 10 March 2011: Salt from the sea, Lake Grassmere

Took this from the air (obviously) on our trip to Wellington - it was a lovely calm day, blue sea and pink salt! The coastline has quite a curve here with Wairau Lagoon, a great place for bird watching in the distance.

Seawater, from the Pacific Ocean, is pumped into Lake Grassmere. Warm north-west winds blow across the exposed lake, evaporating water and increasing the concentration of salt.

The very salty water is pumped into deep holding pens, then into shallow crystallisation ponds. As the water continues to evaporate, salt forms as a crust on the bottom of the ponds. The remaining water is pumped out and the dried salt is harvested, crushed, washed and moved by giant conveyor belts to form huge mounds of sparkling white crystals.

The pink to purple colour of the crystallisation ponds is caused by natural microscopic green algae that change to pink in the high salt concentration. The same phenomena gives the Red Sea its name. There are also small pink shrimps in the water that thrive in this salty environment.

Other salt works in the world are generally much closer to the equator, but Marlborough's abundance of warm north-westerly winds, long hours of sunshine and low summer rainfall provide the evaporation needed to extract salt from the sea at this latitude.

(Thanks to the Marlborough Info Centre for the info!!)

• PENTAX K-x:
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• 1/400":
• 35mm:
• ISO 400

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