Part 3 of 4 - Calculations - CMC Here is an example of the CMC calculation for EB1, step-by-step so you can follow along. For the example of EB1,...

The aquatic ecosystem criterion maximum concentration (CMC) [acute surface-water toxicity limit] for copper at surface water site EB-4 is  micrograms per liter (ug/L). Provide your answer to one decimal place (X.X). 

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This week you will continue working with the Ely Mine data set.

The primary goal this week will be to calculate hazard quotients for acute

aquatic ecosystem toxicity using the data in the "Surface Water" worksheet. Add

your new calculations to the spreadsheet you used last week, as you are

building up the complete data set for this mine project. For any sample with a

concentration below the detection limit, calculate your answer using the

detection limit. There is only one in the assignment. It is the one with the

"<" symbol.

Note: We will only be working with copper in the "Surface Water"

worksheet.

For the "Surface Water" worksheet, you will look at freshwater

acute aquatic ecosystem criteria, otherwise known as the Criterion Maximum

Concentration (CMC). For freshwater chronic aquatic ecosystem criteria, the

chronic guideline is known as the Criterion Continuous Concentration (CCC). For

the homework assignment, you will only have to calculate acute limits, but I

include the chronic expressions just for completeness. I provide the

equations for you below, but you can also find them for copper and other

elements at:

https://www.epa.gov/wqc/national-recommended-water-quality-criteria-aquatic-life-criteria-table

It is worth looking at this web site for future reference. It

will be useful for your mid-term PowerPoint project. You will notice that some

of the CMCs and CCCs are a function of the hardness of the water. (These

criteria will be listed in the table with a footnote "E.")

Note: Aluminum and iron are listed under "Non-priority

Pollutants." Note that all of the CMCs and CCCs listed on the EPA web page were

calculated assuming a hardness of 100 mg/L. Therefore, you can check that you

are doing the calculations properly by calculating CMCs and CCCs for 100 mg/L

hardness.