Seaweed

[Syd]

Taken From Sky News

 

 

British holidaymakers have been warned to avoid beaches in northern France because of toxic fumes from rotting seaweed.

 

Rotting seaweed is cleared from Saint Efflam beach in Brittany

 

 

 

One stretch of beach at Saint-Michel-en-Greve in Brittany has already been shut after a horse rider lost consciousness and his horse died.

 

In another case, a council worker paid to clear beaches of the noxious plants was taken to hospital in a coma.

 

Gilles Youenou, of the French Institute for Sea Research and Exploitation, said: "We would advise people to avoid the beaches in this area as the seaweed can give off hydrogen sulphide fumes.

 

"This is all a result of a problem with agriculture. Nitrates have got into the water and polluted it.

 

"A crust forms over stacks of rotting seaweed and when this crust is broken, fumes get out. It can be particularly lethal to dogs and other animals."

 

 

There are about five beaches that are unusable. The problem is getting worse.

 

French environmental group Eau et Rivieres

 

Jean-Francois Piquot, a spokesman for the French environmental group Eau et Rivieres, told The Times that toxic seaweed has been present on beaches in Brittany for decades and is spreading.

 

He said: "There are about five beaches that are unusable. The problem is getting worse."

 

Up to 70,000 cubic metres of seaweed is cleared off about 70 beaches every summer in Brittany.

 

Pierre Philippe, of the Lannion hospital in Brittany, said hydrogen sulphide was as dangerous as cyanide.

 

He said he had treated several cases of poisoning among local residents.

 

 

 

 

[CliveH]

H2S - Hydrogen Sulphide or rotten egg smell. Odd gas in that when you can smell it it is safe but if your cannot, it either means it has gone OR that it is in very much higher concentrations that our noses cannot detect and at these concentrations it can be lethal.

 

"Hydrogen sulfide (H2S, CAS# 7783-06-4) is an extremely hazardous, toxic compound. It is a colourless, flammable gas that can be identified in relatively low concentrations, by a characteristic rotten egg odor. The gas occurs naturally in coal pits, sulfur springs, gas wells, and as a product of decaying sulfur-containing organic matter, particularly under low oxygen conditions. It is therefore commonly encountered in places such as sewers, sewage treatment plants (H2S is often called sewer gas), manure stockpiles, mines, hot springs, and the holds of fishing ships. Industrial sources of hydrogen sulfide include petroleum and natural gas extraction and refining, pulp and paper manufacturing, rayon textile production, leather tanning, chemical manufacturing and waste disposal.

 

Hydrogen sulfide has a very low odor threshold, with its smell being easily perceptible at concentrations well below 1 part per million (ppm) in air. The odor increases as the gas becomes more concentrated, with the strong rotten egg smell recognisable up to 30 ppm. Above this level, the gas is reported to have a sickeningly sweet odor up to around 100 ppm. However, at concentrations above 100 ppm, a person's ability to detect the gas is affected by rapid temporary paralysis of the olfactory nerves in the nose, leading to a loss of the sense of smell. This means that the gas can be present at dangerously high concentrations, with no perceivable odor. Prolonged exposure to lower concentrations can also result in similar effects of olfactory fatigue. This unusual property of hydrogen sulfide makes it extremely dangerous to rely totally on the sense of smell to warn of the presence of the gas.

 

Health Effects of Hydrogen Sulfide

 

H2S is classed as a chemical asphyxiant, similar to carbon monoxide and cyanide gases. It inhibits cellular respiration and uptake of oxygen, causing biochemical suffocation"

 

So safest thing would be to avoid these places as much as possible. Should be OK on a breezyday but a hot dry still day could be very bad news indeed for anyone strolling on such a beach. And this is indeed what happened to the horse and rider in France it seems.