Instructor’s Guide

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Analytical Sciences Digital Library

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Environmental Analysis: Effects of Acid Rain on Atlantic Salmon Populations

Sections of this overall module:

Sample Gran Plot (Excel)

How this module has been used:

There are several different experimental approaches that can be pursued as identified in the different hypotheses.

This project has been used as an analytical problem based project in Environmental Chemistry, and in a Quantitative Analysis leaning Analytical Chemistry course where the students cover the basic analytical methods and then

Collect water samples,
Obtain field pH measurements over time during spring snow melt,
Measure Acid Neutralizing Capacity (ANC) to identify sites where the water system will be sensitive to acid rain impacts,
Measure nutrient levels (phosphorus and nitrogen containing compounds),
Measure water hardness (titration) and concentrations of Ca²⁺and Mg²⁺ via IC.

The surface waters in the Machias and East Machias watershed are very low conductivity (often about 20 µS/cm), resulting in needing the trace analysis via ion chromatography (IC) rather than titration. The Ca²⁺ concentrations in these watersheds often run about 2 ppm. IC is used as it was the instrument readily available for undergraduate use. Atomic absorption spectroscopy could readily be used, and this process is described in other modules.

These low ionic strength waters also make measuring pH a challenge and require very careful calibration, validation, and measurements.

There is also a remediation project where clam shells are used as a source of calcium carbonate to buffer smaller streams from episodic acid rain events. This project has been used to obtain upstream and downstream analysis to identify the changes in water chemistry from the dissolving shells.

There is sample data provided so this could also be used as a dry lab for students to walk through the data analysis process.

This module in primarily focused on the first two hypotheses spelled out in the Identifying the Problem section.