Gritting – where does it all go?

For the past week or so, the unexpected snowfall has been the major talking point in the news. However this has now been taken over by the news that stockpiles of grit/salt are running dangerously low, something that could bring certain roads in Britain to a standstill. Who knew salt stocks would become such an issue in Britain? Looking back salt has always played an important part in our lives. Many years ago salt was used as a preservative for foodstuffs but over time we’ve been educated in the dangers of excessive salt consumption. Increased levels of salt can lead to illnesses such as hypertension, ulcers, osteoporosis and even death. With the recommended daily allowance (RDA) set at 6g per day, recent government initiatives have been aimed at reducing our salt consumption via the use of Sid the slug and so forth. So would it not be fair to assume that excessive levels of salt would also have a detrimental effect on our countryside and wildlife?

When grit is spread over icy roads, the salt dissolves the ice to form salt water (brine) that is a mixture of sodium and chloride ions.

This brine then flows from the roads into the countryside. As well as seeping into the land, passing vehicles can throw brine up into the air allowing it to become airborne and spreading over a larger area. The gritting trucks themselves scatter the salt with great force which causes the substance to bounce off the road surfaces into adjacent areas. These chloride ions can move through the environment and are resistant to natural decomposition, which can cause upset in the natural balance of things.

With the Romans, once they conquered a city they would often plough the fields with salt so that nothing could be grown. High levels of chloride in the soil can alter pH levels, which may kill micro-organisms and change the structure of the soil. This coupled with increased levels of heavy metal pollutants means that the soil is unable to support growth. In plants themselves, chloride ions can prevent absorption of water and nutrients causing dehydration which eventually leads to the plants dying.

Like humans, wildlife is also affected by salt. Wildlife such as rabbits and so forth are attracted to the roadside pools of salt water and are often killed by passing vehicles. Those that aren’t killed outright are poisoned to death by extreme salt levels. It has been found that some birds are left in a haze which affects their reactions times, again leading to their death. Certain amphibians have permeable skin and so the influx of salt can cause changes in the homeostatic levels within their systems. Going back to Sid the slug, we all know what happens when he is exposed to salt. It has also been shown high levels of salt can kill frog spawn and newt eggs and changes in their breading areas can also cause problems.

Finally coming back to humans again, high salt levels can cause pipe corrosion which can release toxic metals such as lead into our already saltier drinking water. Looks quite bleak all around! I’m not saying we should stopping gritting the roads as that would be chaos – something that we’ve already seen this week. Alternatively, I could also just be making things up – a few equations and plausible science can be quite convincing, lol. But it does make you wonder where all that salt does go.