Salt Study Questions

mridgep

New member
Although time consuming would it have been better to analyze trace elemental concentrations yourself rather than getting averages from a book or previous studies? I thought that it may play a larger than minimal role due to variations in those concentrations from conservative/non conservative metal distributions.

Excuse my ignorance on this next question, but keeping in mind the changes in local SW concentrations of these trace metals how much of a factor do you see in having an organism (if regional) from the East coast such as the urchins peforming in SW from the Long Beach area. Surely the test performance would have proved better if in NSW from the area in which the urchins were collected would they not?

How much greater would you expect the trace metal concentrations to be considering horizontal transport and land based runoff when assessing East and West coast concentrations? Is this a valid factor?

Thank you for your work and contribution to the science and the hobby.

Matthew P. Ridge
 
Re: Salt Study Questions

Originally posted by mridgep

Hi Matthew,

Although time consuming would it have been better to analyze trace elemental concentrations yourself rather than getting averages from a book or previous studies?

Time consuming ain't the problem. Cost is the problem. Using ICP methodology doesn't give very useful results, but it is the cheapest available method. For a suite of, maybe 30 elements, the cost is maybe $250-$300 per salt. However, that methodology can't get anywhere near the ppb or pptrillion range necessary for most trace elements. So... to get into that range, we are talking costs in the thousands of dollars for the study. The $$$ aren't there.... So, one relies on published values.

Surely the test performance would have proved better if in NSW from the area in which the urchins were collected would they not?

Actually the urchins came for the Florida Gulf coast. But, to answer your question, it doesn't make any difference where the salt water is collected from as long as it is free of pollution. Normal variations in trace metals won't effect the urchins at all. And, in case, it was all normalized to the specific wate.

How much greater would you expect the trace metal concentrations to be considering horizontal transport and land based runoff when assessing East and West coast concentrations?

I would not expect any particular variations in trace metal concentrations in the water from either case. Check out the book called "The biogeography of oceans" (I forget the author at the moment) as well as standard chem oceanographic works. There are differences from area to area, but they are minor.

Is this a valid factor?

Generally, larval ecologists and other folks working with the animals simply ignore it. It may be valid to consider, but there is no evidence that it is so.

:D
 
In response to my previous question ( in bold ) and your answer below I consulted my marine chemistry book. For future reference and the curiosity of others I have included a quote regarding trace metals and horiziontal segregation.


How much greater would you expect the trace metal concentrations to be considering horizontal transport and land based runoff when assessing East and West coast concentrations?

I would not expect any particular variations in trace metal concentrations in the water from either case. Check out the book called "The biogeography of oceans" (I forget the author at the moment) as well as standard chem oceanographic works. There are differences from area to area, but they are minor.




From Marine Biogeochemistry by Susan Libes
John Wiley and Sons Inc. 1992 p. 188

Areas...can have dissolved metal concentrations that deviate considerably from the average. ... trace are resolubilized much in the same way as nitrogen, phosphorus, and silicon. This causes many of the trace metal to have depth profile similar to those of the nutrients. ...the horizontal and vertical distributions of dissolved trace metals... can be assessed from the depth profiles of the metals.


Matthew P. Ridge
 
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