Use of oxidation reduction potentials in TIE procedures for confirmation of metal toxicity
- Monsanto Co., St. Louis, MO (United States). Environmental Sciences Center
In support of its ``Policy for the Development of Water Quality-based Toxics Control,`` EPA has developed procedures for isolating and identifying he causes of aquatic toxicity in complex waste mixtures. Chelation procedures using EDTA and sodium thiosulfate are recommended by EPA. While useful to determine whether aquatic toxicity in a water is caused by metals, these tests do not allow for unambiguous identification of toxicity from metal ions. An additional possible method of testing for metal toxicity was investigated, utilizing zero valent metal treatment agents. Metals having high (positive) redox potentials are said to be more noble. These ions can be reduced to the zero valent state and removed from water by metals that are more electronegative. The metal used as a treatment agent must be essentially non-toxic to aquatic test species. Magnesium, iron, and manganese were investigated as zero valent treatment agents. Tests were performed on solutions containing ions of cadmium, copper, nickel, zinc, mercury, cobalt, arsenic, and chrome at 400 ppb in 15% Perrier water or well water prior to treatment. Metals (2--4g) were placed into 0.5 or 1 L of test solutions and shaken for 1 hour. The bulk metal was removed from solution. The solution was aerated for 10 minutes, filtered to remove additional precipitates and pH adjusted to 7.3 with HCl before toxicity testing. ICP-MS and ICP-AES analyses were conducted on aliquots of treated and untreated waters. Magnesium effectively removed all test ions. High concentrations of dissolved magnesium in treated solutions may have interfered with the toxicity tests. Iron metal was effective in removing a number of the metal cations tested, but toxicity was not noticeably reduced. Manganese was not as effective as magnesium in removing all test ions but gave promising test results. Toxicity was markedly decreased after manganese treatment.
- OSTI ID:
- 372545
- Report Number(s):
- CONF-9511137-; ISBN 1-880611-03-1; TRN: IM9641%%622
- Resource Relation:
- Conference: 2. Society of Environmental Toxicology and Chemistry (SETAC) world conference, Vancouver (Canada), 5-9 Nov 1995; Other Information: PBD: 1995; Related Information: Is Part Of Second SETAC world congress (16. annual meeting): Abstract book. Global environmental protection: Science, politics, and common sense; PB: 378 p.
- Country of Publication:
- United States
- Language:
- English
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