Move Over Processed Salt!
Seawater contains just over 2.5 per cent sodium chloride, together with significant amounts of other salt. Some 60,000 to 70,000 tonnes of salt are harvested from Lake Grassmere each year. Sea water is pumped into the 688 hectare main lake continuously throughout summer.
As nature does its work and evaporation increases the sea water’s strength, it is pumped into a series of concentrating ponds, where further evaporation takes place.
When the brine reaches, saturation point it is transferred into crystallization ponds during the summer months.
New Zealand’s Marlborough province is renowned for receiving more than its share of sunshine. It was this meteorological feature, coupled with strong, drying Nor’ Westerly winds and large areas of suitable flat land, that persuaded the late George W. Skellerup to establish his solar salt works in 1943.
The salt crust is lifted from the bottom of the crystallization ponds and transported to one of the two washing plants where it is washed in brine before being stacked in 20-metre high piles.
The snowy stacks of salt are something of a landmark, readily visible by day and night from the Blenheim – Christchurch highway. Salt production is highly dependent on low rainfall and evaporation, so it is necessary to hold large stockpiles of salt to counter the fluctuations in annual production.
Visitors to Lake Grassmere frequently ask why the brine in some ponds looks a pink color. The color is due to the presence of extremely large numbers of a microscopic unicellular algae organism. Normal Algae are green, but when existing in concentrated brine, haematochrome (a red pigment) is formed in the organism giving it a pink or reddish appearance. Algae and bacteria are the organisms responsible for the pinkish-red tinge (from which the Red Sea gets is name).
The brine shrimp - sometimes called the brine worm and scientifically known as Artemia Salina - prefers to live in seawater so saturated with salt that it would kill any other form of marine life. Experiments have established that the shrimp is happiest in brine containing about a hundred grams of salt to five hundred milliliters of water. The movements of this tiny creature are graceful and vigorous - it swims on its back, its feet being in constant motion and its course being directed by means of its long tail. Its color is pink to red and millions of shrimps and their brownish colored eggs gather in corners of the salt ponds. They have a beneficial effect on salt making by grazing on the algae and sealing the pond bottoms. The brine shrimp is always found at well-established salt works and has appeared at Lake Grassmere by natural means, without any attempt to introduce it artificially