Bulrush storing toxins

[Calurix]

I was watching Wild Britain and R. Mears ate the immature heads and later used the pollen from Bulrush.

After a search on the forum I found this

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Bulrushes aren't poisonous, the roots are a bit too stringy this time of year, you can eat the shoots as well. There is a similarity with irises which at moment have bright yellow or blue flowers. The roots of iris are knobbly and stink of pig poo when cooked, they make a purple die.

The main danger from bulrushes is that they absorb pollution from water very easily. They are used as toxic sponges in the wirral to soak up dioxin and heavy metals. Personally I like to know what the industrial history of the area I pick them from and the natural history of the water course that feeds them.

Would pollen be safe from Bulrush in a filter bed or will the whole plant be contaminated ?

 

[forestwalker]

I would be suspicious, and avoid them unless you were certain that there was nothing in the effluent water that had passed throught the bed than a bit of extra nitrogen and phosphates.

 

[IanM]

Reed beds are often used to purify sewage contaminated water because of their ability to take up toxins by bacterial action.

Wikipedia Entry

 

[Calurix]

Thanks, I think I will just keep to using the heads for tinder.

 

[Toddy]

I grow the small variety, typhus minima, in my garden pond. The flowering heads produce a tremendous amount of protein rich pollen
You can grow the bullrushes (I know, we're supposed to call it reedmace, but if I say bullrush everyone knows the plant I mean) in a big bucket. I've got one of the full size ones growing, flowering and producing big seed heads in a tiny wee spill over pond in the front garden. It can't hold more than a kitchen sinks worth of water. They're really hardy plants The stems are good for basketry too.

cheers,
Toddy

 

[EdS]

Reed beds are often used to purify sewage contaminated water because of their ability to take up toxins by bacterial action.

Wikipedia Entry

Not quiet - -Reedbeds are not used to take up toxins. They are used to treat sewage in a similar way to a normal filter works. Only difference is that the biota that "breaks down" lives on the root structure of the plants rather than on the filter media. The water depth in a reedbed sewage works needs to shallow to allow for aerobic conditions close to the root zone so that the biota (not just bacteria) can do their job.

It is the biota on the roots that do the work not the plants themselves. That said the reed with take up some nitrates, but that is more or less negligible. They can also be used to polish final effluent from a normal works.

Normally with a reed bed system a settling tank system similar to a septic tank is the first stage of treatment. Then there is the reedbed. In the reedbed a number of species are planted in different zones of the beds ie reeds, rushes and finally flag iris.

In a former life I used to look after a few of them - when they where still about. They can work ok, but are very labour and land intensive and will not treat as well as a small modern package plant with a smaller footprint. They are also very seasonal - don't really work when the freeze. OK for 1 or 2 domestic properties but too big and inefficient for much else in the UK. Now somewhere warm and sunny wit hlots of land and cheap labour ie Africa - they can be a via able option for small villages.

Discharge qualities have vastly improved and consents tightened since they where used for small villages etc in the UK.

 

[IanM]

So, what happens to the heavy metals and persistent organics? They must go somewhere.

 

[EdS]

stay where they are. Some may be taken up if they are in solution via ion exchange in the roots, they amount depends on the species and "pollutant". Heavy metals are more readily taken up as they are positive charged ions in solution so may be taken up via the mechanism for other metal ions. Not so much in larger organic molecules.

Trees tend to be better at taking up heavy metals - for a number or reason inc the shear volume of water/ions they take up. Rowan is good and Alder readily absorbs certain heavy metals. Alder is a practical plant to use as it both fixes it own nitrogen and will not only tolerate but grow in water logged conditions.

So course you then have to dispose of any cuttings/wood as special waste.

 

[xylaria]

I made the orginal statement because I live in an urban area with long and dirty industrial history. Most wetlands within stoke are on reclaimed industrial sites like coal fields and pottery sites where heavy metals are serious issue.

Sewage treatment beds aren't toxic, EdS is the expert but in my understanding bulrushes help break down the pathogenic bacteria, that is the plant cleaning the water by breaking down human manure and making it safer. Industrial toxons are stored because they aren't natural

 

[EdS]

but of cross threading hear I guess.

Sewage is generally these days not contaminated with heavy metals & organics. Yes are some but not a high levels. They are usually prevented from gettig into the sewerage system in the first place. When accidents do happen they tend to kill the sewage works not matter what the process. It is the microbes - bacteria, protozo etc that break down sewaage, that get hammeres but toxins.

Now in contaminated water bodies ie ponds, lakes rivers, that have been polluted due to historic use palnt can be used as part of long scale restoration (usually towards the end). They will take up contaminats - some more than others and soem species more readily. However, this is just a result their normal nutirent pathway taknig the pollutants up "by accident". They remain in the plant tissue as ther is no biological use for them.

Also some toxins may be concentrated in the leaves in autumn so they end up bakcv in the growing medium.

The amount taken up is not enough to quickley remediate a site. It jsut a case of a little at time taken up and a little vegetation pruned.

 

[jimjolli]

Are Reed Mace and Bullrush definitely the same thing, I've never had a definite answer??

I have roasted the roots and they are actually really tasty. After roasting on the embers of a fire you peel away the outer stringy bit and chew the inner core, spitting out the fibre afterwards. High in carbs.