SYMPOSIA PAPER Published: 01 January 2000

Importance of Ionic Composition of Reconstituted Laboratory Test Water in Interpreting Metal Toxicity Test Results


We compare the ionic composition of ASTM reconstituted water with surface waters of the United States. The relative concentrations of major cations in surface waters are variable: Ca:Mg molar ratios range from 0.3 to 12.9, and Na:K molar ratios range from 1.4 to 600. However, the relative concentrations of these cations in ASTM reconstituted water are constant: the Ca:Mg molar ratio is 0.7 and the Na:K molar ratio is 21.3. Recent research has demonstrated that Ca is more important than Mg in modifying metal toxicity to salmonids. Hence, differences in the relative concentrations of these cations between surface waters and ASTM reconstituted waters may bias metal toxicity results. We also evaluate the potential for Na to modify Cu toxicity in salmonids. Sodium concentrations as high as 32.S mg/L did not influence Cu toxicity. These results indicate that ASTM reconstituted water may not be appropriate for metal toxicity tests.

Author Information

Welsh, PG
Stratus Consulting Inc., Boulder, CO
Chapman, GA
Paladin Water Quality Consulting, Corvallis, OR
Hansen, JA
Stratus Consulting Inc., Boulder, CO
Lipton, J
Stratus Consulting Inc., Boulder, CO
Price: $25.00
Contact Sales
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Developed by Committee: E47
Pages: 3–15
DOI: 10.1520/STP10241S
ISBN-EB: 978-0-8031-5448-3
ISBN-13: 978-0-8031-2886-6