Water pollution

[WildCassieThing]

Hi guys and girls,

I've been asked a question today that I am struggling to find an answer too; What aquatic plants species specific, are being damaged by water pollution?

My children are trying too dirve me nuts I swear it!

Every link I use on google leads me to a eutrophication page, or will tell me about lead accumulation in fish. Any help will be much appreciated

WCT

[wanlock dod]

WCT,

You have already found your answer, probably the main impact on aquatic plants (aside from physical or habitat related effects) is eutrophication. Whilst this might not cause any direct toxicity it does alter the ecosystem structure, by favouring certain species over others. Environmental regulators look a benthic diatoms and macrophytes as indicators of the impacts from these stressors.

However, in terms of actual toxic effects, and specific species that is probably rather more tricky. Herbicides will have an effect on local aquatic plant species, but the most affected species would probably depend upon the particular herbicide used, and the differing sensitvities of the different plant species. The ecotoxicity information tends to be restricted to a limited number of (easy to culture) standard test species and the complictaed results of microcosm and mesocosm studies. Most of the standard test species are unicellular planktonic algae.

Some metals, such as zinc, will (probably) affect plants under certain conditions. This tends to be where the pH is high, such as in chalk streams in the South East of England, but depends a lot on the local water chemistry conditions. Again, it is probably not possible to say which individual species would be likely to be affected in any individual case.

Cheers,

Dod

[tom00_uk]

all depends on the pollution, what are you looking at?
heat, chemical, physical etc

a taker full of milk going into a small stream or pond would have negative impacts. in part from the turbidity, but also from the massive BOD (biological oxygen demand) required to break it down

oil on the surface would affect light penetration and gaseous exchange

metals are less of a issue for plants, and its their ability to take in large quantities that has seen the growth in reed beds to try and treat mine leachate. Though you then have plants that can be inedible and accumulate levels where they are classed as hazardous waste

[wanlock dod]

Tom,

It seems odd to me that you should suggest that because there are some plants which are relatively insensitive to metals that all plants are therefore insensitive to metals. Midge larvae are commonly considered to be relatively insensitive to low dissolved oxygen concentrations, so does this mean that all invertebrates (or all animals?) are similarly insensitive to low dissolved oxygen concentrations?

Dod

[tom00_uk]

ops did not mean for it to look that way, it was a quick post before heading back north,

Life has adapted to different niches in a myriad of ways, some plants and animals can live in conditions that you would expect them to shy away from or to do so poorly they die out.

plants do seem to be very tolerant if they have their basic requirements meet, they can cope with a wide range of things thrown at them. but there will all ways be a limit. Some times the object posing a toxic reaction can be quite benign but if its chemical structure is very close in shape to a essential metal and found in either a higher concentration or a more biologically free form it can be taken up more readily.

Though far from harmless to most things cadmium can readily be taken up in the place of calcium, the same is true of zinc.

You will find a lot of papers written on the effect of cadmium v calcium if you under take a gscholar search as it seems to be a favourite chemical for playing with in the laboratory, from my experience.

Though this still does not answer the question asked by WildCassieThing

I've been asked a question today that I am struggling to find an answer too; What aquatic plants species specific, are being damaged by water pollution?

, as though they want to know what species are effected by pollution, they have not hinted at what form of pollution is affecting said plants.

[wanlock dod]

Tom,

Ca does have a protective effect against the toxicity of Cd and Zn (and some other metals), although there are other water quality conditions which can be rather more important (pH and organic matter). I think you will find that the term you are looking for is "Biotic Ligand Model".

If you do some digging into Zn ecotoxicity I am sure you will find that algae are at least amongst the most sensitive creatures, but especially so at high pH. You might find it worthwhile to have a read of this paper on the start of your search for enlightenment on the issue: Bioavailability models for predicting acute and chronic toxicity of zinc to algae, daphnids, and fish in natural surface waters - De Schamphelaere - 2009 - Environmental Toxicology and Chemistry - Wiley Online Library. You should at least be able to follow the majority of it, it is a pretty good and digestable summary (although things have moved on a little since then), but give me a shout if you want any of it explaining.

Dod

[King Edward]

Originally Posted by wanlock dod

It seems odd to me that you should suggest that because there are some plants which are relatively insensitive to metals that all plants are therefore insensitive to metals.

A lot of wetland plant species are naturally highly resistant to heavy metals, unlike most dryland plants which are not. For instance, see this: Wetlands ecosystems in Asia ... - Google Books

[tom00_uk]

dont think assistance is needed, spend many hours stuck in the lab with Daphnia magna, Mytilus edulis, Dicentrarchus labrax, and a range of crustaceans (shore, brown crab, lobster) carrying out toxicology investigations. But with no lab at present I am unable to easily view papers (with out paying).

Its tempting to get back in the lab again, ideally back in Norway, though currently enjoying being paid to watch marine mammals and turtles offshore.

[wanlock dod]

So back to the original question then?

BOD will certainly cause effects on aquatic ecosystems, but it tends to be fish and invertebrates that are affected. A quick look at the proposed water quality standard for oxygen in rivers suggests that plants are not particularly sensitive to this as a pressure (http://www.wfduk.org/stakeholder_rev...gValinUKRivers)

As you say, oil will have an important effect on gaseous exchange, but this will (again) be more important to animals than plants.

Heat can also cause problems (as you rightly suggest), but as the main effect is on gas solubility again the main effects will most likely be on animals.

So are we back to the key likely culprits being eutrophication, herbicides and metals (under certain conditions)?

King Edward, yet more insensitive species dont alter the fact that some species are sensitvie, or do you believe that all animals are as insensitive to low oxygen concentratiosn as midge larvae?

Tom, with that kind of a background you should consider SETAC membership (that would give you access to these journals, setac.org). However, I can summarise a few results from the abstract for you. The most sensitvie results (in these studies) were 185 ppb for fish (O. mykiss), 59 ppb for invertebrates (D. magna), and 27 ppb for algae (P. subcapitata). One of the conclusions that we can draw from this is that some plants are sensitvie to zinc. There are other field studies which have also noted this sensitvity, some diatoms show characteristic distortions in the presence of metals, and at a rate which is linearly correlated with zinc concentrations.

I admire your enthusiasm, but lets not close our minds to new knowledge, or draw premature conclusions where there is nothing to justify them.

Dod