Bing try this one from one of the links.

Bill Cody
Lunker
Member # 24

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posted September 03, 2004 11:14 PM
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My data base for total Cu in the hydrosoil(sediments) is still relatively in the beginning stages. I have not kept up with sampling for that type of research anymore. My data is mostly from the early 1990's when copper sulfate was used extensively around here in NW Ohio. It is still used a lot but due to my "preaching" and intensively "spreading the word". As a result it is not used and recommended as indescriminately at least locally as it was in the past.

The concentration that you found in the hydrosoil seems somewhat low from my experience for a pond that has had frequent use of CuSO4. Ten to 20 yr old ponds, up here in the limestone-clay based soils that have had frequent moderate to heavy doses of CuSO4, have total Cu concentrations that range from 100 to 500 mg/Kg in the hydrosoils; some at even a little higher levels (measured w/ flame atomic absorption).

Sediments under these extreme Cu conditions are for practical purposes, basically dead and I could not find benthic invertebrates or active bacteria present in any of those sediments. In ponds with our typical limestone soil chemistries, experience has shown that, once the Cu concentration in the hydrosoil accumulates to around 400-500 mg/Kg (800-1000 lbs/acre) much of the copper from new additional treatments will remain dissolved in the water column and does not percipitate. It "appears" that the sediments are "full" or saturated with Cu and new copper additions "hesitate" to percipitate out of the water as usual. Thus the water column contains free Cu ions sometimes at concentrations of up to 2 mg/L that persist for extended periods. Length of persistance "seems" to depend on variaables including the application rates & time since the last CuSO4 treatment.

At Cu concentrations of 7 - 10 mg/Kg in the pond sediments around NW Ohio, I have collected a few living invertebrates such as oligochate worms, nematodes and a few larval insects (rarely burrowers). I am not real sure of the concentration of Cu where the invertebrtates are completely eliminated. It is no doubt on a gradual scale that is affected by the buffering capacity of the hydrosoil and the sensitivity ranges of the many different species of invertebrtates that inhabit the pond bottom. As the copper levels increase, more and more types of benthic invertebrates are probably eliminated from the habitat, with the most Cu sensitive dying first and the most tolerant dying last. Invertebrate reproductive capacities and growth or development of egg through instar stages are also probably affected by the abnormally high Cu concentrations.

As far as I know, very little in-depth research has been done with high concentrations of Cu complexes in teh hydrosoil. Numerous Cu toxicity studies have been reported in the scientific literature but they did not test the real high Cu concentrations that we taking about and at concentrations that are no doubt present in numerous, chemically, mismanaged ponds.

Copper Remediation. From my experience very little can be done to remediate these high copper concentrations in the hydrosoil. Nature's law -- Copper is a heavy metal and heavy metals are stable in the environment. Copper is now on at least three governmental agency lists (USEPA, CERCLA & SARA) as a priority pollutant or hazardous/toxic chemical. In the future as more of its affects are studied we will earn more about its impact and long term affects in the pond system. We have had some success percipitating the persistant free copper ions out of the water column with lime and alum treatments in order for "normal" phytoplankton and zooplankton communities to redevelop.

Natural coppper concentrations in the hydrosoil of some lakes has been studied and it was discovered that under certain conditions copper will redissolve from the sediments and enter the water column. This was found to occur primarily during fall turnover or destratification.

[ September 05, 2004, 09:20 PM: Message edited by: Bill Cody ]