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BIOGEOCHEMICAL, HEALTH, AND ECOTOXICOLOGICAL PERSPECTIVES ON GOLD AND GOLD MINING - CHAPTER 6

CHAPTER 6 The Effects of Gold on Plants and Animals Lethal and sublethal effects of Au0, Au+, and Au+3 are summarized for aquatic organisms and laboratory mammals. Gold accumulations from solution are documented for microorganisms and other living resources under various physicochemical conditions. 6.1 AQUATIC ORGANISMS This section summarizes lethal and sublethal effects of Au+ and Au+3 on aquatic microorganisms, plants, fishes, and amphibians. 6.1.1 Monovalent Gold Monovalent gold is toxic to aquatic biota at comparatively elevated concentrations of 7.9 mg Au/L and higher (Nomiya et al. 2000). Toxicity of gold to microorganisms is affected by concentration and oxidation state of gold, presence of competing metal ions. | CHAPTER 6 The Effects of Gold on Plants and Animals Lethal and sublethal effects of Au0 Au and Au 3 are summarized for aquatic organisms and laboratory mammals. Gold accumulations from solution are documented for microorganisms and other living resources under various physicochemical conditions. 6.1 AQUATIC ORGANISMS This section summarizes lethal and sublethal effects of Au and Au 3 on aquatic microorganisms plants fishes and amphibians. 6.1.1 Monovalent Gold Monovalent gold is toxic to aquatic biota at comparatively elevated concentrations of 7.9 mg Au L and higher Nomiya et al. 2000 . Toxicity of gold to microorganisms is affected by concentration and oxidation state of gold presence of competing metal ions in solution pH and composition of the growth medium Savvaidis et al. 1998 . Exposure to gold may induce cell adaptation and cell resistance as has been demonstrated for monovalent gold chloride sodium aurothiomalate and auranofin. Cellular adaptation is a potential mechanism for gold resistance Savvaidis et al. 1998 . Antimicrobial activities of two isomeric Au -triphenylphosphine compounds were documented for two species of Gram-positive bacteria Bacillus subtilis Staphylococcus aureus and one species of yeast Candida albicans at concentrations as low as 7.9 mg Au L for bacteria and 250.0 mg L for yeast Nomiya et al. 2000 . Growth inhibition of Tetrahymena pyriformis a ciliate protozoan is reported after 24 hours in 99 to 296 mg Au L as gold sodium aurothiomalate and prolonged cell generation time at 390 to 2960 mg L in 24 hours Nilsson 1993 . At 1576 mg Au L no cells died in 24 hours although endocytosis and cell proliferation were inhibited after 2 days however the cell density of the culture was sufficiently high 65 66 PERSPECTIVES ON GOLD AND GOLD MINING to permit recovery Nilsson 1993 . Exposure of Tetrahymena to 3050 mg Au L as gold sodium aurothiomalate for 24 hours equivalent to eight normal cell generations resulted in a growth reduction of 50 and .