Mn, Cu, Co, Zi, Ni, Fe toxicity

[norskfisk]

Mn, Cu, Co, Zi, Ni, Fe are important nutrients for algae. You will find them in algae growth mediums. Anybody know if they can be toxic at the levels of detection for Triton ICP-OES?


Here are the detection limits plus NSW consentration. Everything is ppb:


Mn (0.116 - 0.384) NSW 0.165
Cu (1.18 - 3.5) NSW 0.380
Co (0.382 - 1.4) NSW 0.006
Zn (0.149 - 0.7) NSW: 0.590
Ni (0.502 - 0.87) NSW: 0.7
Fe (0.307 - 1.4) NSW 0.14

 

[Diesel]

That's a question for Randy.

 

[Randy Holmes-Farley]

Not sure what you mean by "at the levels of detection for Triton ICP-OES?".

The Triton detection limits you posted are the lowest levels they can quantify, not the upper levels.

There are levels of those that they can detect that would be toxic to some marine creatures.

Do you mean below the levels that they can detect, or exactly at the detection limit?

An additional complication is that ICP says nothing about the chemical state. Even ignoring that there are different inorganic forms of these with different toxicities of (e.g., ferrous vs ferric iron), organics will bind many of these in seawater or marine aquaria, and the nature and concentration of those organics modulates the toxicity greatly.

So one cannot easily go from a measured total concentration to a direct gauge of toxicity. This issue is well known to scientists.

It has also been shown in our hobby. Ron Shimek found that to be the case when he crusaded against copper in salt mixes, then found that used aquarium water was less toxic than new salt mix at the same total copper concentration.

 

[Randy Holmes-Farley]

There are also different types of toxicity. There is acute toxicity, and chronic toxicity. Acute toxicity kills rapidly (a day or two) and requires higher concentrations. Chronic tox is more like slow poisoning and may simply make something sickly. It requires a lot less.

That all said, copper in my tank when I last carefully measured it years ago was about 10-15 ppb. I don't think it was a tox concern at that level (above the Triton detection limit), but there is not data available on every organism that I kept, or that others keep in reef aquaria. I noticed to tox, but that doesn't mean there wasn't any for any creature in the tank.

So all in all, it is a very hard question to answer.

 

[norskfisk]

Thanks Randy, I understand it is hard to answer.


Sorry for being a bit unclear. What I meant was that for these elements the ICP-OES will/may show 0 for concentrations at natural seawater level. So if I was to dose those elements and use ICP-OES for controlling the concentration I would have to go higher than NSW levels to be sure the concentrations are not actually 0. For cobalt, for example, that means more than 833 times higher. So the question then is if such high concentrations are bad for anything living?


By toxic I meant "any negative effect at all, on anything". Sort of as a starting point for discussion ;-). I understand the issue of toxicity is endlessly complex of course.

 

[Randy Holmes-Farley]

Thanks Randy, I understand it is hard to answer.


Sorry for being a bit unclear. What I meant was that for these elements the ICP-OES will/may show 0 for concentrations at natural seawater level. So if I was to dose those elements and use ICP-OES for controlling the concentration I would have to go higher than NSW levels to be sure the concentrations are not actually 0. For cobalt, for example, that means more than 833 times higher. So the question then is if such high concentrations are bad for anything living?

Right, You could not use the ICP data to try to match NSW levels of some of the trace metals.

As to tox, I'm not sure if "none detected" is an assurance that there is no toxicity of all of these, but I think for copper it is pretty good (since I have had copper above their detection limit without apparent issue). Probably iron too, since I and many others dose it. Hard to say about cobalt as the gap between detection and NSW levels is so large.

Bear in mind that the NSW levels that Triton gives are, seemingly, ocean averages. For some things that are actively taken up by organisms (iron, copper zinc, etc) the surface values can be far lower than the ocean average. As much as 10-100 x lower in some cases.

 

[Ehsan@triton]

Thanks Randy,

please Norskfisk have in mind that the TRITON ICP test is always the secound instance the first is always your tank.
What I mean by that is if everything is ok in your tank and all animals are healthy, and the ICP is showing a 30 ppb of copper there is no need to act or panic, we are not chasing Numbers here we keep animals.
It could be bound to for example Humic acid and be "detoxified", this is a good reed for things like that (Randy might know it) : Organic Compounds in the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com

the other way around when you are struggeling with your tank the best way would be starting to get things in line again, so you could at least not blame the Chemistry of your tank to much, and search for other errors if the problem is still there.

All the best Ehsan:smile: