Size-reduced samples of southern yellow pine dimensional lumber, each treated with one of five different waterborne chemical preservatives, were leached using 18-h batch leaching tests. The wood preservatives included chromated copper arsenate (CCA), alkaline copper quaternary, copper boron azole, copper citrate, and copper dimethyldithiocarbamate. An unpreserved wood sample was tested as well. The batch leaching tests followed methodology prescribed in the U.S. Environmental Protection Agency toxicity characteristic leaching procedure (TCLP). The wood samples were first size-reduced and then leached using four different leaching solutions (synthetic landfill leachate, synthetic rainwater, deionized water, and synthetic seawater). CCA-treated wood leached greater concentrations of arsenic and copper relative to chromium, with copper leaching more with the TCLP and synthetic seawater. Copper leached at greater concentrations from the arsenic-free preservatives relative to CCA. Arsenic leached from CCA-treated wood at concentrations above the U.S. federal toxicity characteristic limit (5 mg/L). All of the arsenic-free alternatives displayed a greater degree of aquatic toxicity compared to CCA. Invertebrate and algal assays were more sensitive than Microtox. Examination of the relative leaching of the preservative compounds indicated that the arsenic-free preservatives were advantageous over CCA with respect to waste disposal and soil contamination issues but potentially posed a greater risk to aquatic ecosystems.

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The toxicity and physicochemical parameters of municipal solid-waste (MSW) landfill leachates from six sites in north and north-central Florida, United States, were determined. Landfill leachates are complex mixtures of organic and inorganic constituents. Leachate toxicity was assayed using the acute C. dubia (48-h) and Microtoxtrade mark (15-min) assays and the chronic S. capricornutum (96-h) assay. The landfill leachates were shown to be highly toxic to both C. dubia and S. capricornutum with an EC(50) < 10% and < 15%, respectively. However, Microtoxtrade mark was not as sensitive to the leachates. Based on these results, the assays were ranked for their sensitivities to the landfill leachates; C. dubia > S. capricornutum > Microtoxtrade mark. Chemical analyses showed high concentrations of un-ionized ammonia and salts in the landfill leachates but low concentrations of heavy metals. The toxicity of the landfill leachates varied between the sites sampled and within each of the landfill sites. A significant relationship was found between the total ammonia content of the leachates and toxicity as determined by the C. dubia and S. capricornutum assays. Although the chemical constituents in Florida MSW landfill leachates may be more dilute, the toxicity of the leachates is equivalent to that from industrial waste landfills.

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