Review of Lithium in the Aquatic Environment: Distribution in the United States,Toxicity and Case Example of Groundwater Contamination

Lithium is found at low concentrations in the major rivers of the United States (about 0.002mgl^–1) and as a mineral or salt in pegmatites and brines. The United States produces many lithium materials and consumes the greatest amount of Li in the world for use in ceramics, glass, aluminum, pharmaceuticals, batteries, etc. From 1950 to 1970, Li was central to many nuclear-related US Department of Energy (DOE) activities. The historical and current use of Li has not prompted many studies of the toxicity of this element to aquatic organisms. Here, we review the distribution and use of Li in the US with emphasis on usage by DOE. We also summarize information on the toxicity of lithium to aquatic biota. A case-example is provided which demonstrates the potential for contamination of groundwater with Li, evaluates the toxicity of the Li-contaminated groundwater, and identifies a treatment alternative.     

Derivation of Aquatic Screening Benchmarks for 1,2-Dibromoethane

Ethylene dibromide (1,2-dibromoethane or EDB) was primarily used in the United States as an additive in leaded gasoline and as a soil and grain fumigant for worm and insect control until it was banned in 1983. Historical releases of EDB have resulted in detectable EDB in groundwater and drinking wells, and recently concentrations up to 16 Î&frac;g/L were detected in ground water at two fuel spill plumes in the vicinity of the Massachusetts Military Reservation Base on Cape Cod, Massachusetts. Because the ground water in this area is used to flood cranberry bogs for the purposes of harvesting, the U.S. Air Force sponsored the development of aquatic screening benchmarks for EDB. Acute toxicity tests with Pimephales promelas (fathead minnow), Daphnia magna, and Ceriodaphnia dubia were conducted to provide data needed for development of screening benchmarks. Using a closed test-system to prevent volatilization of EDB, the 48-h LC₅₀s (concentration that kills 50% of the test organisms) for P. promelas, D. magna, and C. dubia were 4.3 mg/L, 6.5 mg/L, and 3.6 mg/L, respectively. The screening benchmark for aquatic organisms, derived as the Tier II chronic water quality criteria, is 0.031 mg EDB/L. The sediment screening benchmark, based on equilibrium partitioning, is 2.45 mg EDB/kg of organic carbon in the sediment. The screening benchmarks developed here are an important component of an ecological risk assessment, during which perhaps hundreds of chemicals must be evaluated for their potential to cause ecological harm.Received: 19 July 2002/Accepted: 24 January 2003     

Source of toxicity in storm water: zinc from commonly used paint

A Department of Energy site in Paducah, Kentucky (USA), stores thousands of cylinders of depleted uranium hexafluoride. Breaches of the cylinders could result in the release of uranium and hydrogen fluoride. Beginning in 1996, a program was begun to paint the cylinders in order to prevent corrosion of the cylinders and the surfaces of the storage yards were converted to concrete. In 1998, storm water from the cylinder storage yards was found to be toxic to Ceriodaphnia, at concentrations exceeding limits in the site's discharge permit. A six-month study was conducted to identify the source of the toxicity in the storm water. Ceriodaphnia toxicity tests with the storm water resulted in 48-h median lethal concentrations (LC50) ranging from 12 to 94%; zinc concentrations in the storm water ranged from 0.08 to 0.54 mg/L. Acute toxicity tests with zinc and linear regression identified that zinc concentrations in the storm water were sufficient to account for the toxicity observed. By tracking the sources to the discharge point, newly painted cylinders were identified as the source of the zinc in the storm water. Rainwater collected directly from the painted cylinders contained up to 13 mg Zn/L. Laboratory and field tests showed that topcoating the cylinders would reduce the amount of zinc in the runoff from the cylinders.     

Toxicity of Lithium to Three Freshwater Organisms and the Antagonistic Effect of Sodium

Lithium (Li) is the lightest metal and occurs primarily in stable minerals and salts. Concentrations of Li in surface water are typically <0.04mg l^–1 but can be elevated in contaminated streams. Because of the general lack of information concerning the toxicity of Li to common toxicity test organisms, we evaluated the toxicity of Li to Pimephales promelas (fathead minnow), Ceriodaphnia dubia, and a freshwater snail (Elimia clavaeformis). In the laboratory, the concentration of Li that inhibited P. promelas growth or C. dubia reproduction by 25% (IC25) was dependant upon the dilution water. In laboratory control water containing little sodium (2.8mg l^–1), the IC25s were 0.38 and 0.32mg Li l^–1 and in ambient stream water containing 17mg Na l^–1, the IC25s were 1.99 and 3.33, respectively. A Li concentration of 0.15mgl^–1 inhibited the feeding of E. clavaeformis in laboratory tests. Toxicity tests conducted to evaluate the effect of sodium on the toxicity of Li were conducted with fathead minnows and C. dubia. The presence of sodium greatly affected the toxicity of Li. Fathead minnows and Ceriodaphnia, for example, tolerated concentrations of Li as great as 6mg l^–1 when sufficient Na was present. The interaction of Li and Na on the reproduction of Ceriodaphnia was investigated in depth and can be described using an exponential model. The model predicts that C. dubia reproduction would not be affected when animals are exposed to combinations of lithium and sodium with a log ratio of mmol Na to mmol Li equal to at least 1.63. The results of this study indicate that for most natural waters, the presence of sodium is sufficient to prevent Li toxicity. However, in areas of historical disposal or heavy processing or use, an evaluation of Li from a water quality perspective would be warranted.