Adding magnesium to the silver-gill binding model for rainbow trout (Oncorhynchus mykiss)

✍ Scribed by Melissa L. Schwartz; Richard C. Playle

• Publisher: John Wiley and Sons
• Year: 2001
• Tongue: English
• Weight: 105 KB
• Volume: 20
• Category: Article
• ISSN: 0730-7268
• DOI: 10.1002/etc.5620200302

✦ Synopsis

Abstract

Rainbow trout (Oncorhynchus mykiss; 2–17 g) were exposed to approximately 0.1 μM silver as AgNO~3~ for 3 to 4 h in synthetic, ion‐poor water (20 μM Ca, 100 μM Na, 150 μM Cl, pH 7) to which was added Mg, Ca, or thiosulfate (S~2~O~3~). Gills were extracted and assayed for Ag using graphite furnace atomic absorption spectrophotometry. Up to 210 mM Mg (four fold the concentration of Mg in seawater) did not reduce accumulation of Ag by trout gills. The conditional equilibrium stability constant (K) for Mg at silver‐binding sites on the gills was calculated to be log K~Mg‐gillAg~ = 3.0, or approximately half‐as‐strong binding as for Ca at these sites. The inclusion of the Mg‐gill stability constant into the original Ag‐gill binding model increases the flexibility of the model, although the competitive effects of Mg are only important in sodium‐poor systems.