UK smog: Nitrogen doesn't just cause air pollution - it is a huge threat to Britain's wildlife too, experts warn


The nitrogen pollution contributing to Britain’s smog poses the biggest threat to wildlife that the public has never heard of – with the potential to wipe out everything from clover to butterflies in eco-systems across the country – experts have warned.

The amount of nitrogen stored in the soil as a result of soaring emissions from agriculture, power stations and cars is now so great it has reached critical levels in the majority of non-agricultural land, according to Clare Whitfield, air pollution consultant at the government’s statutory conservation adviser.

Nitrogen-rich soil reduces biodiversity because it causes species which thrive on nitrates to flourish at the expense of those that don’t.

“Nitrogen represents a major threat to biodiversity in the UK and across Europe. It is an under-acknowledged and very big issue that has slowly crept up on us,” said Ms Whitfield.

The rapid accumulation of nitrogen in the soil has already damaged eco-systems across the country as thick outcrops of beneficiaries such as grass, heather, thistles and nettles “swamp out” a wide range of species such as flowers, bees, beetles, lizards, snakes and spiders by depriving them of water, space, light and the other conditions they need.

High levels of nitrogen also cause problems by leaching into groundwater which can impair the blood’s oxygen-carrying capacity in small infants causing “blue baby syndrome” and can be toxic for ruminants such as cattle and sheep.

The problem has got worse in recent years and, with the majority of eco-systems outside agriculture above the ‘critical load’ for nitrogen, that trend is set to continue, Ms Whitfield said. The critical load is the point beyond which the rate of nitrogen deposited from the air to the ground poses an increasing risk of habitat damage.

Once in the ground, nitrogen can remain for hundreds, even thousands of years while the level of accumulation is not measured and its potential impact not fully understood, experts said.

“The nitrogen level is building up all the time as we continue to add to the pot and increase the cumulative impact,” Ms Whitfield added.

Her comments will increase pressure on the government to get nitrogen levels under control two months after the European Commission launched legal proceedings against it for failing to reduce “excessive” levels of nitrogen dioxide air pollution from traffic, despite 15 years of warnings and several extensions and postponements granted to the government.

Other European countries have also failed to meet the air quality directive – that should have been adopted in 2008 – but the EU environment commissioner, Janez Potocnik, has singled out Britain for its “persistent” breaches of the air quality directive. The government has been sent a letter of the  formal notice of the intention to take Britain to court the government has until next Friday (April 18th) to respond.

Unlike so-called natural and semi-natural habitats, which are generally harmed by rising nitrogen levels, farmland is benefitting from the increase – and fuelling it - because crops benefit enormously from nitrogen-rich fertilisers. Ammonia, a pungent colourless compound of nitrogen and hydrogen released by livestock exacerbates the problem.

“This is the biggest threat to biodiversity that the public is not aware of. For wildlife it really is a pernicious and pertinent cause of decline in very many species as the burning of fossil fuels turns the volume of nitrate falling onto habitats from a drizzle to a downpour,” said Matt Shardlow, head of the Buglife insect charity.

“The longer we keep pouring this into natural habitats, the more it accumulates and unless we can reverse the situation we can expect many of these declines to continue,” he added.

Getting nitrates out of the ground is a “real challenge”, Mr Shadlow said. Methods include a sustained programme of “cropping off” – or burning – and removing vegetation, or deep ploughing, when a tractor turns over the top metre of soil to bury the nitrates further underground.

Nitrogen emissions also need to come down, Mr Shardlow said. “There is no obvious sign of that happening at the moment but that could start to come down with hybrid and electric cars,” he said – but adds that even if that does happen, the accumulation of nitrates in the soil will be so high that it will still need to be dealt with.

A spokesman for the Department for Environment, Food and Agriculture (Defra) said: “Air quality has improved significantly in recent decades. Just like for other [EU] member states, meeting the NO2 (nitrogen dioxide) limit alongside busy roads has been a challenge.”

“That is why we’re investing heavily in transport measures to improve the air quality around busy roads and we are working with the Commission to ensure this happens as soon as possible,” he added.

The species being edged out by rising nitrogen levels in the soil

Wildflowers such as Bird’s Foot Trefoil and Clover which don’t thrive on nitrogen and get shaded out by the plants, which also consume the water

Bees and other pollinators suffer because fewer flowers mean less nectar

Grasshoppers may eat grass but they still suffer when too much of it takes over their environments, because they like to lay their eggs in the bare ground so they can be exposed to the sunlight and grow.

Cirl buntings are hindered because they eat grasshoppers, which are in decline

Capercaillie and black grouse suffer because their chicks get trapped in the cold, dense, wet heather

Caterpillars suffer because the increase in plants makes the ground colder

Reptiles such as lizards and snakes are hurt by the loss of the bare ground they need to bask in

Butterflies such as the Large Blue and Silver spotted Skipper suffer because they need large, bare habitats to survive

Insects such as beetles and ants, which require warm chalky or sandy ground on which to nest, suffer from dense vegetation

Start your day with The Independent, sign up for daily news emails
Have you tried new the Independent Digital Edition apps?
ebooksAn introduction to the ground rules of British democracy
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Sales Account Manager - OTE £60,000

£35000 - £60000 per annum: Recruitment Genius: In 2014, they launched the worl...

Recruitment Genius: Digital Design Lead

£23958 - £29282 per annum: Recruitment Genius: One of the North West's leading...

Guru Careers: Bathroom Showroom Manager / Bathroom Sales Designer

£22 - £25k basic + Commission=OTE £35k + Benefits: Guru Careers: A Bathroom Sh...

Recruitment Genius: HR Recruitment Advisor

£21000 - £23000 per annum: Recruitment Genius: This provider of children's ser...

Day In a Page

Refugee crisis: David Cameron lowered the flag for the dead king of Saudi Arabia - will he do the same honour for little Aylan Kurdi?

Cameron lowered the flag for the dead king of Saudi Arabia...

But will he do the same honour for little Aylan Kurdi, asks Robert Fisk
Our leaders lack courage in this refugee crisis. We are shamed by our European neighbours

Our leaders lack courage in this refugee crisis. We are shamed by our European neighbours

Humanity must be at the heart of politics, says Jeremy Corbyn
Joe Biden's 'tease tour': Could the US Vice-President be testing the water for a presidential run?

Joe Biden's 'tease tour'

Could the US Vice-President be testing the water for a presidential run?
Britain's 24-hour culture: With the 'leisured society' a distant dream we're working longer and less regular hours than ever

Britain's 24-hour culture

With the 'leisured society' a distant dream we're working longer and less regular hours than ever
Diplomacy board game: Treachery is the way to win - which makes it just like the real thing

The addictive nature of Diplomacy

Bullying, betrayal, aggression – it may be just a board game, but the family that plays Diplomacy may never look at each other in the same way again
Lady Chatterley's Lover: Racy underwear for fans of DH Lawrence's equally racy tome

Fashion: Ooh, Lady Chatterley!

Take inspiration from DH Lawrence's racy tome with equally racy underwear
8 best children's clocks

Tick-tock: 8 best children's clocks

Whether you’re teaching them to tell the time or putting the finishing touches to a nursery, there’s a ticker for that
Charlie Austin: Queens Park Rangers striker says ‘If the move is not right, I’m not going’

Charlie Austin: ‘If the move is not right, I’m not going’

After hitting 18 goals in the Premier League last season, the QPR striker was the great non-deal of transfer deadline day. But he says he'd preferred another shot at promotion
Isis profits from destruction of antiquities by selling relics to dealers - and then blowing up the buildings they come from to conceal the evidence of looting

How Isis profits from destruction of antiquities

Robert Fisk on the terrorist group's manipulation of the market to increase the price of artefacts
Labour leadership: Andy Burnham urges Jeremy Corbyn voters to think again in last-minute plea

'If we lose touch we’ll end up with two decades of the Tories'

In an exclusive interview, Andy Burnham urges Jeremy Corbyn voters to think again in last-minute plea
Tunisia fears its Arab Spring could be reversed as the new regime becomes as intolerant of dissent as its predecessor

The Arab Spring reversed

Tunisian protesters fear that a new law will whitewash corrupt businessmen and officials, but they are finding that the new regime is becoming as intolerant of dissent as its predecessor
King Arthur: Legendary figure was real and lived most of his life in Strathclyde, academic claims

Academic claims King Arthur was real - and reveals where he lived

Dr Andrew Breeze says the legendary figure did exist – but was a general, not a king
Who is Oliver Bonas and how has he captured middle-class hearts?

Who is Oliver Bonas?

It's the first high-street store to pay its staff the living wage, and it saw out the recession in style
Earth has 'lost more than half its trees' since humans first started cutting them down

Axe-wielding Man fells half the world’s trees – leaving us just 422 each

However, the number of trees may be eight times higher than previously thought
60 years of Scalextric: Model cars are now stuffed with as much tech as real ones

60 years of Scalextric

Model cars are now stuffed with as much tech as real ones