Chlorinated dioxins and dibenzofurans (PCDD/F) were measured in 107 soil samples globally, and depositional fluxes were determined. Deposition to land surfaces was estimated by dividing the earth into five depositional zones based on climatic and geographical factors. Mean depositional fluxes to these zones ranged from 18 to 610 ng m -2 yr -1 . Low fluxes were observed in most zones not impacted by industrialization. Total global deposition from the atmosphere to land was estimated to be 12 500 ( 1300 kg/yr. Based on limited data, deposition to the oceans was estimated to be about 610 ( 1500 kg/yr, yielding a total global deposition of 13 100 ( 2000 kg/yr from the atmosphere. Emissions of PCDD/F to the global atmosphere were estimated by determining emission factors and production rates for the major PCDD/F sources. The major sources considered in this study were municipal waste incineration, biomass combustion, steel and copper mill emissions, cement kiln emissions, medical waste incineration, and emissions from automobiles Total annual emissions were estimated to be 3000 ( 600 kg. Global deposition (see above) is roughly four times greater than annual emissions. This suggests that sources of PCDD/F are not well-characterized. More data are needed on emission factors (particularly from developing countries) and on introduction rates of PCDD/F to the global atmosphere.

Abstract-Ecotoxicological assessments of contaminated soil aim to understand the effect of introduced chemicals on the soil flora and fauna. Ecotoxicity test methods were developed and conducted on hydrocarbon-contaminated soils (Ͻ5,000-30,000 mg/kg total petroleum hydrocarbon) and on adjacent uncontaminated control soils from eight field locations. Tests included 7-d, 14-d, and chronic survival tests and reproduction assays for the earthworm (Eisenia fetida) and seed germination, root length, and plant growth assays for corn, lettuce, mustard, and wheat. Species-specific responses were observed with no-observed effect concentrations (NOECs) ranging from Ͻ1 to 100% contaminated soil. The 14-d earthworm survival NOEC was equal to or greater than the reproduction NOEC values for numbers of cocoons and juveniles, which were similar to one another. Cocoon and juvenile production varied among the control soils. Germination and root length NOECs for mustard and lettuce were less than NOECs for corn and wheat. Root length NOECs were similar to or less than seed germination NOECs. Statistically significant correlations (p Ͻ 0.05) for earthworm survival and seed germination as a function of hydrocarbon measurements were found. The 14-d earthworm survival and the seed germination tests are recommended for use in the context of a risk-based framework for the ecological assessment of contaminated sites.

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Ecotoxicological assessments of contaminated soil aim to understand the effect of introduced chemicals on the soil flora and fauna. Ecotoxicity test methods were developed and conducted on hydrocarbon‐contaminated soils (<5,000–30,000 mg/kg total petroleum hydrocarbon) and on adjacent uncontaminated control soils from eight field locations. Tests included 7‐d, 14‐d, and chronic survival tests and reproduction assays for the earthworm (Eisenia fetida) and seed germination, root length, and plant growth assays for corn, lettuce, mustard, and wheat. Species‐specific responses were observed with no‐observed effect concentrations (NOECs) ranging from <1 to 100% contaminated soil. The 14‐d earthworm survival NOEC was equal to or greater than the reproduction NOEC values for numbers of cocoons and juveniles, which were similar to one another. Cocoon and juvenile production varied among the control soils. Germination and root length NOECs for mustard and lettuce were less than NOECs for corn and wheat. Root length NOECs were similar to or less than seed germination NOECs. Statistically significant correlations (p < 0.05) for earthworm survival and seed germination as a function of hydrocarbon measurements were found. The 14‐d earthworm survival and the seed germination tests are recommended for use in the context of a risk‐based framework for the ecological assessment of contaminated sites.

The indoor air concentrations of aldrin and dieldrin, two organochlorine termiticides, were monitored in the basement, main level, and upstairs area of a treated home. Aldrin and dieldrin concentrations were measured in the home between September 1987 and April 1995. Aldrin and dieldrin concentrations were highest in the basement, where the aldrin and dieldrin had been applied. Aldrin concentrations decreased with a half-life of 16 months in both the main level and basement of the home, but dieldrin concentrations remained the same over the study period. In 1995, we expanded our measurements to include the indoor and outdoor air concentrations of a set of organochlorine compounds used as pesticides. These compounds include aldrin, dieldrin, four chlordanes, pentachloroanisole, and the hexachlorocyclohexanes. All compounds except the hexachlorocyclohexanes had higher indoor than outdoor air concentrations, implying that their sources were in the home. In the indoor air, aldrin, dieldrin, and the chlordanes had higher concentrations in the basement than on the main level, indicating a basement source. Pentachloroanisole was evenly distributed throughout the indoor air, implying that it does not originate in the basement. Two remediation attempts were made to stop aldrin and dieldrin from infiltrating into the home. First, the basement walls were covered with tar and plastic to form a barrier against the foundation. Second, the basement air pressure was manipulated. While the tar and plastic appear to have had little effect, creating a positive indoor air pressure lowered the air concentrations of the two pesticides.