So with all this unnecessary (IMO) salt being dug up from salt mines in cheshire and NI and then dumped on the roads to make a lovely slushy mess to ride/drive through, has anyone thought/studied the impact it will have as it gets taken down into our waterways?

what's the likely impact on fresh water plant and wildlife?

Probably no more than all the road grime diesel/oil and over spray from farmers and all the other crap that gets dumped tipped pored into the national water courses.

The melt water that washes it down will probs dilute it somewhat.

We've a lovely salt mine in Northern Ireland and its near my home town leave it alone! It produces half a million tonnes of de-icing salt per annum!

I guess the answer is 'what's the alternative?'

http://www.saltsense.co.uk/deicing-environ01.htm

May not be entirely unbiased however!

And if a water way was to polluted with to much salt and impacted the wildlife in anyway then the Environment Agency could take the local county council to court for pollution.

I fish for barbel,and BFW (barbel fishing world) consider this almost as often as we do what snow tyres.The consensus appears to be that very little long term damage is done,probably to dilution by melt water,but it doesn't half put the fish off feeding for a few days.
ian

When you say it puts them off feeding does that mean they bite less or actually eat less? Is it becasue they don't need to get salt from any other source?

plants do not enjoy drinking saline fluids…osmosis and all that.

bearing in mind the sea is rather salty and hence so is rain in coastal areas…

not an answer here be interested to hear from a pro!

thejesmonddingo- something to do with increased conductivity (uSeimen)?
or just grumpy 😀

Not sure,barbel feeding is greatly reduced as temperatures dip below about 4c,when the temperature increases feeding ,and so catch rates,improve,but when there's been a lot of road salting the period immediately post melt is notoriously bad for bites,until the salt flushes through.Not sure of the mechanism,as barbel live in tidal rivers,and are often caught in relatively brackish water.
Ian

bearing in mind the sea is rather salty and hence so is rain in coastal areas

Uh oh, there might be a very small misunderstanding here of how rain works…

We will all be under salt water with global warming so spreading salt is simply preparing the ground…..

bannanworld- according to research undertaken recently by lecturors here at uni, the concentration of NaCl in rainwater increases as sample sites become closer to the sea- hence seawater has a bearing on the salt within rain?

but yeah generally i am mistaken 😀

I've often thought about the effect on the environment from all the salt we use on the roads. No idea what the answer is, but I imagine that it has some sort of effect, after all, it's not exactly small quantities. I would have thought that most freshwater fish can handle a reasonable amount of salt (saline solution is often used to treat infections in aquarium fish – although the Corydoras genus of catfish is noted for it's very low tolerance of salt) not sure about the effect on bacteria and plants though – or invertebrates.

the concentration of NaCl in rainwater increases as sample sites become closer to the sea

Is that likely to be because in high winds spray from waves mixes up in the atmosphere with rain ?

Be nice if it killed of all the invasive weeds and crayfish.

ernie- hmmm thats very interesting actually, it depends on how far inland spray can travel because i believe the sample sites went inland a few miles…def a factor though (runs off to poke lecturor)

depends on how far inland spray can travel

Presumably winds can carry molecules of sea spray for several miles inland ?

After all, the rain which falls far inland in the UK originates from exactly the same source as that which falls in the coastal areas, ie, it mostly originates from evaporated water from the Atlantic Ocean – no ? So the clouds are no different ?

salty rain? next to the sea? are you sure?

should be no worse than the road grime, diesel, oil, fag butts etc that are washed off the roads on a normal daily basis. The drains etc should go to specific discharge points. More importantly, I am sure that the Environment Agency will have thought of this and have something in place. They are pretty keen on discharges to watercourses (rightly so).

Put vinegar on the roads as well and save us all the effort when we "kill it, cook it, eat it".

Sorted!

should be no worse than the road grime, diesel, oil, fag butts etc

Is it though ? Is salt not very stable, whereas diesel, oil, fag butts etc, can all be broken down as necessary in sewage plants ?

Depends if it gets into the sewer Ernie……

Most just gets washed off into streams and rivers.

in northern US i recall driving in pretty icey conditions and some sections of road had signs warning they were not gritted for environmental reasons err edit highway

*hangs head in shame at lack of knowledge…seconds earlier thought that he's not an acedemic…leaves room*

😀

i would say that salt is a lot less bad than any hydrocarbon. but i do work with water not sewage.

Salt, Grit and the Environment

At the Raynes Park Community Forum on 5 February 2009 a resident asked about the environmental impact of salt and grit used on icy roads. I wrote to the Environment Agency and the Highways Agency. Both sent very helpful replies. Since their views were very similar I have reprinted the more detailed response from the Highways Agency below.

Bartle Sawbridge
Neighbourhood Governance Officer
Stronger Communities Team
Chief Exec’s Department
0208 545 4400
 
Grit or salt?
Although most of us call it gritting, there is in fact, no grit involved. The stuff spread on the roads is rock salt, taken from an underground mine in Cheshire.
It is more or less the same as the rock salt you’d grind onto your food, other than it is brown due to containing an impurity of Marl, which is a type of clay.
We spread salt onto the road, but it works best when it goes into a solution. We rely on the tyres of cars passing over the top of it to crush the salt onto the road. This then forms a solution with a higher de-icing capability.
Water freezes at 0C, but the salt stops the water from freezing until -6C to -8C.
If it snows, we spread 40g of salt per square metre on the roads before the snow comes. Then as the snow falls we continue salting and we use snowplough attachments if the snow accumulates.

Does the melting salt/marl have any adverse environmental impact?
 
             Rock salt is the major de-icing agent used on roads in the UK and the HA has undertaken some research into its potential impacts and alternative products and application methods. It is comprised of > 90% Sodium Chloride , 2-4% water, anti-caking agents. It can contribute to elevated levels of sodium and chloride in receiving waters when applied to the road service and quickly followed by a rainfall event. Laboratory toxicity tests have shown that high sodium and chloride levels could have a potential impact on some invertebrates but that fish are quite tolerant for short durations – this is not so surprising given that many fish species often live in brackish waters.
 
It is also recognised that a relatively low level of dilution is all that may be required to protect aquatic communities. Any potential effect within receiving watercourses is dictated by the amount of available dilution. As Rock Salt is only used in the winter months it is unlikely that rivers and streams will be flowing at low flows (typically experienced in summer months) when it is discharged. In fact the opposite is more likely with winter rainfall events providing a higher degree of dilution in water bodies. As all highway discharges are by their very nature intermittent and of a short duration the exposure is likely to be low. Where highway discharges are treated by balancing ponds a higher level of dilution and protection will be provided with a much slower release to the receiving watercourse.
 
The Highways Agency have in recent years been looking at a number of ways of reducing its rock salt usage and has a commitment with the Environment Agency to work towards this without compromising road safety and operation of the Strategic Road Network. Recent initiatives are;
 
1. The investment in a new fleet of salters that use better technology to control the application of salt more efficiently and effectively on roads surfaces. This minimises the wastage and reduces the risk of over-salting the roads.
 
2. The HA is currently investigating alternatives to the use of rock salt on roads. One product being explored is the use of Agricultural By-products which can be mixed with Rock Salt thereby reducing the amount of salt used and the release of Sodium Chloride into receiving waters. This is currently being trialled and its environmental and safety benefits in comparison to Rock Salt will be evaluated.

Presumably winds can carry molecules of sea spray for several miles inland ?

I think perhaps you mean "very small droplets" as the molecules are really very small indeed and unlikely to be seperated from each other in a spray. It gets a bit more complicated when you consider that salt in sea water is not really present as salt but as dissolved ions of sodium and chloride…

But anyway, no matter. I am VERY interested to hear how proximity to the coast affects rainwater salinity. Does it matter which way the wind blows/where the prevailing wind comes from?

I think perhaps you mean "very small droplets"

Well "very small droplets" didn't seem small enough for the point I was trying to make, but yeah, I can understand how individual molecules might not be the issue. Although I do remember how once many years ago, I heard David Attenborough say on a TV programme that a blood hound's nose is so sensitive, that it can quite literally pick up a scent from just a few molecules. I've never being able to get my head round that concept, and if it wasn't for the fact that it was said by the man himself, I would have dismissed it as bollox.

"I am VERY interested to hear how proximity to the coast affects rainwater salinity."

And I'm very slightly interested, to hear why you are VERY interested ? 😕

bit of salt, bit of chilli, bit of honey and some lime juice. that way we can marinade the fish at source.

seem to recall taking samples on a fieldtrip to measure levels of airport antifreeze in local watercourses. do airports still do that?

am sure there'll be research on salt>watercourses. probably from the 1970s when we used to get proper winters. 🙂

And I'm very slightly interested, to hear why you are VERY interested ?

I'm VERY interested simply because I cannot imagine how rainwater could become salty "a few miles" inland from the sea. I'm not gonna say it's impossible as walla reports that the samples are in, but I would love to hear what mechanism is at work, and if/how prevailing winds and offshore/onshore breezes affect it.

Sorry to be pedantic about the molecules/droplets thing, BTW…

I can forgive the Highways Agency for "road service", when they obviously mean road surface, but "rainfall event" 🙄

Some trivia;
Normally, trucks have their tachographs calibrated every 6 years and checked every 2 years for older analogue tachos, or calibrated every 2 years for digital tachos.
The gritting gear is linked to the speedo so that the gritter spreads the right amount of grit per metre.
Gritting lorries have a full calibration every year to ensure they are always as accurate as possible.

A friend of mine drives a gritter. He told me about some new system that uses a liquid salt solution instead of rock salt. I think it's still being trialled, or maybe even still just a proposal. I don't think it's in use yet.

in northern US i recall driving in pretty icey conditions and some sections of road had signs warning they were not gritted for environmental reasons err edit highway

I enjoyed two winters in Alberta and they use grit and not salt on the snowy and icy roads.

When the snow and ice melts in the spring they come along with road sweepers and collect all of the grit which by this time is lining the gutters and hard shoulders. They can then reuse the grit next winter.

Seems a much better way of doing business if you ask me.

big wide roads with not a lot either side in Alberta though, not sure over here our narrow verged/pzvemented/hedged set up would cope as well. We'd be driving in grit drifts by March (assuming similar levels of snow to Alberta).

I was thinking about the Canadian approach again this afternoon. The reason that they don't use salt is that they could never hope to melt all of the snow. When it arrives it stays around all winter.

Normally over here when it snows it does so for a short period of time, down goes the salt, snow melts, no more snow falls , end of story.

Global warming then cooling… 😉

maybe the fish come out cured, ready made ganvadlax

Laboratory toxicity tests have shown that high sodium and chloride levels could have a potential impact on some invertebrates but that fish are quite tolerant for short durations….

Impact on some invertebrates ? So it presumably, has possibly the potential have quite a devastating effect on fish then ? …….even if it's indirect 💡

I enjoyed two winters in Alberta and they use grit and not salt on the snowy and icy roads.

When the snow and ice melts in the spring they come along with road sweepers and collect all of the grit which by this time is lining the gutters and hard shoulders. They can then reuse the grit next winter.

Seems a much better way of doing business if you ask me.

That's the Ski resort approach as well. Interesting thread this – i've wondered the same thing.

But anyway, no matter. I am VERY interested to hear how proximity to the coast affects rainwater salinity. Does it matter which way the wind blows/where the prevailing wind comes from?

This seems completely concievable to me. Some years back I remember cards being covered in sand after a rainstorm. Supposedly it was saharan sand that had been picked up by weird weather patterns. A big storm at sea could concievably through a lot of salt water into the air. More of this would fall closer to the coast.