What you need to know about copper and coral

[HighlandReefer]

Habib,

Thanks much for the link. Great info.

"Tatu: Think twice , NO thrice before posting anything"

This appies to me as well. :lol:


I wish I was around in the good old days.

:beer:


Any guess for the amount of time that it may take for inorganic copper introduced into a reef tank to bind to organics in a reef tank? Hours, days or perhaps a week?

I will get around to reading the links you posted.

 

[Habib]

I wish I was around in the good old days.

Were men were men and dinosaurs were dinosaurs.

Any guess for the amount of time that it may take for inorganic copper introduced into a reef tank to bind to organics in a reef tank? Hours, days or perhaps a week?

I will get around to reading the links you posted.

Minutes, hours a day or so. Treating fishtanks with ionic copper requires regular dosages because copper gets bound to decoration and organics.

So it's (bio)availability reduces relatively rapidly.

 

[HighlandReefer]

"Treating fishtanks with ionic copper requires regular dosages because copper gets bound to decoration and organics."

Any personal experiences or theories based perhaps on science you care to share regarding dosing copper. There could be more to this than what I have read as standard descriptions regarding supplements sold. Not much as far as scientific articles that I can find except what I have posted.

 

[Habib]

Cliff, with treating fishtanks I meant treating fish against diseases with copper.

E.g. http://edis.ifas.ufl.edu/fa165

 

[HighlandReefer]

Just reading through this article & it seems that the percentage of Cu++ in seawater almost doubles between pH 8.1 down to 7.8. Would this mean the total copper level recommendation for 30 ppb would be reduced the same amount?

Effect of Ocean acidificationon the Speciation of Metals in Seawater (2009)
www.tos.org/oceanography/archive/22-4_millero.pdf

"Metals that form strong complexes with carbonate include Cu2+, UO22+,
and the rare earths. These metals will be most strongly affected by the change in pH, resulting in an increase in their free ionic forms. The largest percentage increase for carbonate-dominated metals is for Cu2+ (30%).

Table 1. The fraction forms of metals in seawater as a function of pH and time (Caldeira and Wickett, 2003) at 25°C
and salinity of 35. Species contributing less than 5% are not included. All the calculations are made on the free pH scale.


pH/Cu2+ Percentage:

pH 8.1 - 7.67%

pH 8.0 - 9.64%

pH 7.9 - 12.04%

pH 7.8 - 14.92%

pH 7.7 - 18.32 %

pH 7.6 - 22.26%

pH 7.5 - 26.75%

pH 7.4 - 31.76 %
-----------------------------------------------------------------------------------

When using ozone in a reef tank, this will strip the copper from organic compounds. Any guess as to how much increase in Cu++ that may occur?

 

[tmz]

Thanks CLiff. That's a nice table . So if I'm reading it correclty, the % of total copper present as free copper Cu 2 roughly doubles if ph drops to 7.8 form 8.1.

 

[HighlandReefer]

That's the way I understand it, yes.

Would the recommendation for total copper in a reef tank be reduced to say 15 ppb at a pH level of 7.8?

My concern is that Cu++ is toxic in short periods of time to coral, perhaps hours and the damage is done.

 

[tmz]

At first galance it seems to support a case for ph closer to or above nsw values. I doubt we'll know whether a tank is at 30ppb or 15ppb at the hobby level.

I didn't see anything in the study that would give a sense of time other than projections over years for unbinding though and the fromulae are too difficult for me to handle and extrapolate. I'd reckon it would be a relatively fast speciation but might be slower for the portion of total copper bound to refractory organics. Don't know.

 

[HighlandReefer]

Chemical speciation of trace metals in seawater: a review (2006)
http://mounier.univ-tln.fr/rcmo/php_biblio/PDF/5233.pdf

From it:

"Chemical Model of Trace Metals

One of the purposes for the chemical speciation of trace metals
is application to chemical modeling of the ocean. Many kinds
of models for ocean systems have been proposed to have a
better understanding of ocean systems and to predict the future
of the oceanic environments; it includes physical models i.e.,
general ocean circulation model,137 biogeochemical models138,139
and ecological models.140 There are a few oceanic models
including chemical reactions, especially, the complexation of
bioactive trace metal ions with ligands in dissolved organic and
particulate matter. Recently, a chemical model including metal
complexation has been proposed.141

Chemical speciation studies58,67,99,136 have revealed that two
types of dissolved organic ligands are related to the
complexation of trace metals, such as Cu and Zn, in seawater.
However, there is little information on the ecological and
biogeochemical roles of each ligand, except for the metal
buffering capacity.142 In order to elucidate the ecological roles
of dissolved organic ligands in the marine environment,
therefore, a chemical model, including the relationship between
the total Cu and free Cu2+ concentrations in the presence of each
ligand, is effective
.
According to our present knowledge of dissolved organic
ligands,69 the concentrations in seawater are 1 – 3 nM for L1 and
20 – 60 nM for L2. The free Cu2+ concentration in seawater
reflects the reactivity of Cu, and is directly related to the
ecological role to marine microorganisms.31,32 The free Cu2+
concentration in seawater was calculated as a function of the
total Cu concentration based on the chemical equilibrium
model,141 in which the effects of Ca and Mg were taken into
account. The result is shown in Fig. 2. For the presence of only
a stronger organic ligand (L1), the free Cu2+ concentration
showed a sigmoid curve in the range of natural occurring Cu
concentrations in seawater; the free Cu2+ concentration was
maintained at a lower level (less than 1 pM) when the total Cu
concentration was less than that of the stronger organic ligand,
whereas the free Cu2+ concentration steeply increased at a Cu
toxic level (more than 10 pM)30,143,144 when the total Cu
concentration exceeded that of the stronger organic ligand. On
the other hand, for the weaker organic ligand (L2), the free Cu2+
concentration showed a different behavior, in which the free
Cu2+ concentration was maintained at lower level (less than 10
pM) within the natural occurring concentration range of the
total Cu in seawater. The increase in the ligand concentration
shifts the free Cu2+ concentration to lower levels. These
findings suggest that a weaker ligand plays a more significant
role than a stronger ligand to reduce Cu toxicity to marine
microorganisms under higher Cu conditions. This result is
consistent with the finding that a weaker ligand can dominate
Cu speciation in coastal water with higher Cu concentrations.145"

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pM copper concentration = what ppb?

I wonder which types of lignand would be more likey present in a tank without macroalgae?

 

[Randy Holmes-Farley]

I wouldn't jump to conclusions here.

I discuss the various unchelated forms of copper in this article:

http://reefkeeping.com/issues/2003-04/rhf/feature/index.php

from it:

"The portions of metals in seawater that are not bound to organic materials are very complicated in their own right. Copper, for example, takes at least 7 different soluble inorganic forms in seawater.4 It is comprised of Cu++ (3.9% of the inorganic copper), CuOH+ (4.9%), Cu(OH)2 (2.2%), CuSO4 (1%), CuCO3 (73.8%), Cu(CO3)2-- (14.2%) and Cu(HCO3- )+ (0.1%). "


OK, so we have an idea of the forms copper takes in seawater when not complexed to organics. But what we do not know is which of these forms most contribute to toxicity. They are all rapidly converted, but I would be very hesitant to assume that free Cu++ is a lot more toxic than CuSO4 or Cu(OH)2 ion pairs. In fact, since the latter two are neutral, it might actually be absorbed more readily than charged forms and hence might be more toxic.

 

[Randy Holmes-Farley]

When using ozone in a reef tank, this will strip the copper from organic compounds. Any guess as to how much increase in Cu++ that may occur?

The toxicity of metals is one of the hypothesized ways that ozone might contribute to HLLE and related issues, so I think there is reason to be concerned. Could be as much as 10-fold increase if it is otherwise 90% complexed.

 

[HighlandReefer]

Back to the.......

"A little learning is a dang'rous thing; Drink deep, or taste not the Pierian spring: There shallow draughts intoxicate the brain, And drinking largely sobers us again."

Again, I am intoxicated with what knowledge I have aquired. :lol:

Thanks for keeping me straight Randy.

 

[Habib]

.......
............


OK, so we have an idea of the forms copper takes in seawater when not complexed to organics. But what we do not know is which of these forms most contribute to toxicity. They are all rapidly converted, but I would be very hesitant to assume that free Cu++ is a lot more toxic than CuSO4 or Cu(OH)2 ion pairs. In fact, since the latter two are neutral, it might actually be absorbed more readily than charged forms and hence might be more toxic.

Freshwater with various anions might be able to supply the answer.


Effects of inorganic complexing on the toxicity of copper to Daphnia magna
R.W. Andrew, K.E. Biesinger, G.E. Glass
U.S. Environmental Protection Agency, Environmental Research Laboratory-Duluth, 6201 Congdon Boulevard, Duluth, Minnesota 55804, U.S.A.
Received 26 September 1976. Available online 10 April 2003.
http://dx.doi.org/10.1016/0043-1354(77)90064-1,

Abstract
Effects of carbonate-bicarbonate, orthophosphate, and pyrophosphate on the toxicity of copper (II) to Daphnia magna were studied at constant pH and total hardness. Mortality rates and reciprocal survival times were directly correlated with cupric (Cu2+) and copper hydroxy (Cu(OH)n) ion activities as determined by equilibrium calculations. Toxicity was negatively related to activities of soluble copper carbonate (CuCO3) and other complexes, and was found to be independent of dissolved copper or total copper concentrations.



There might be some for sulfate.

 

[Habib]

This one is, at least in my opinion, very very interesting regarding corals; uptake by passive diffusion through cell membranes.

http://www.vliz.be/imis/imis.php?module=ref&refid=60578 (most of it on that page is Dutch/Flamish but the abstract is in English, pasted here below)


Abstract:
The effect of organic complexation, salinity, and pH on the uptake and toxicity of copper in Artemia was studied. The results were compared with data on the chemical speciation and lipid solubility of copper in saline solutions.
The uptake experiments took 90 min and the toxicity tests 24h. A computer model was used to calculate the saline solution equilibrium speciation. The lipid solubility of copper was determined in a series of saline/olive oil partition tests.
Complexation of copper by EDTA reduced the uptake and toxicity of copper. Salinity had no apparent effect on both processes. The results of these uptake and toxicity experiments agreed well with the copper speciation and lipid solubility data. The effect of pH on the uptake and toxicity of copper is more complex. The uptake rate is maximal around pH 7.6 and lowest below 7.0. The toxicity increases towards alkaline conditions. These results do not relate to the speciation and lipid solubility data in a straightforward manner.
Possibly two distinct ligands determine the biological availability of copper in solution. Ionized species interact with the charged ligands present on the external surface of cell membranes (i.e. glycoproteins, proteins, polar heads of lipids) and neutral species move across the lipid bilayer by passive diffusion.

 

[HighlandReefer]

"Abstract
Effects of carbonate-bicarbonate, orthophosphate, and pyrophosphate on the toxicity of copper (II) to Daphnia magna were studied at constant pH and total hardness. Mortality rates and reciprocal survival times were directly correlated with cupric (Cu2+) and copper hydroxy (Cu(OH)n) ion activities as determined by equilibrium calculations. Toxicity was negatively related to activities of soluble copper carbonate (CuCO3) and other complexes, and was found to be independent of dissolved copper or total copper concentrations."

If this happens to be true in saltwater, then one might extrapolate this information by percentage, since (Cu(OH)n) does not change with lower pH down to 7.8:

Perhaps this change in Cu2+ to mean that a recommendation of highest total copper could be 22 ppb (down from 30 ppb) if the pH remains at 7.8 for a few hours?

 

[tmz]

This one is, at least in my opinion, very very interesting regarding corals; uptake by passive diffusion through cell membranes.

Hello Habib, Thanks for the links. I'm drinking my coffee and staring at this one waiting fro my braincells to take it up via passive diffusion but it isn't happening yet.:idea:

 

[disc1]

pM copper concentration = what ppb?

1pM of Cu2+ is 0.0000635ppb Cu2+ or 0.0635 parts per trillion.

 

[HighlandReefer]

Thanks David.

I didn't realize that it is possible to detect such an extremely low concentration of copper.

 

[HighlandReefer]

0.0635 parts per trillion or 63.5 parts per quadrillion. :lol:

 

[Habib]

This one is, at least in my opinion, very very interesting regarding corals; uptake by passive diffusion through cell membranes.

Hello Habib, Thanks for the links. I'm drinking my coffee and staring at this one waiting fro my braincells to take it up via passive diffusion but it isn't happening yet.:idea:

Post #70 of Randy:

.....but I would be very hesitant to assume that free Cu++ is a lot more toxic than CuSO4 or Cu(OH)2 ion pairs. In fact, since the latter two are neutral, it might actually be absorbed more readily than charged forms and hence might be more toxic.

The article by Blust et.al. mentions that neutral copper species are possibly adsorbed by passive diffusion.

That is, by passing the cell membrane not through channels.

This is a small quote from their article:


"Possibly two distinct processes determine the biological availability of copper in solution. Ionized species interact with the charges present on the external surface of cell membranes (i.e. glycoproteins, proteins, polar heads of lipids), while neutral species move across the lipid bilayer by passive diffusion."