Passive air samplers (PAS) using XAD-resin were deployed at a wide variety of sites around the world for four years to asses the spatial and temporal trends of legacy organochlorine pesticides (OCPs) and current use pesticides (CUPs) in the global atmosphere. Legacy OCPs are prevalent in developing countries, whereas certain CUPs dominate in North America and Europe. OCP levels are declining world wide. Concentrations from the XAD-based PAS agreed with those from polyurethane foam (PUF) disk PAS within a factor of 4 for most sites. The comparison revealed that the sampling rate of the PUF-based PAS is more dependent on wind speed, whereas that of the XAD-PAS has a higher dependence on temperature. Analysis of PAS deployed across arid, subtropical Botswana showed that recent use has more impact on present day air concentrations than historical use. Year-long measurements by high volume air sampling in Botswana yielded higher HCB levels in winter, and higher endosulfan levels in summer. Those variations are neither related to temperature fluctuation nor seasonal hydrological events, and are therefore more likely caused by pesticide usage pattern. Very low levels of OCPs were found in the warm, dry, low organic matter soils of Botswana, including in soils from historical use areas. Such soils appear to have a low long-term storage capacity for pesticides allowing for rapid volatilization. They are thus not long-term sources of pesticides to the atmosphere. Endosulfan sulfate levels were observed to increase in tropical soils with increasing elevation. Water samples from high altitude cloud forests in Costa Rica contained very low concentrations of CUPs and it is unlikely that that those levels pose a threat to amphibians in cloud forests. Laboratory experiments and literature analysis showed that the inert gas stripping method for the determination of air-water partitioning equilibria is susceptible to surface sorption artifacts for chemicals with a interface-air partition coefficient log (KIA/m) > -3. Using larger bubbles reduces the surface-to-volume ratio and produces accurate air-water partition coefficients for chemicals with log (KIA/m) < -1.2.

Passive air samplers (PAS) using XAD-resin were deployed at a wide variety of sites around the world for four years to asses the spatial and temporal trends of legacy organochlorine pesticides (OCPs) and current use pesticides (CUPs) in the global atmosphere. Legacy OCPs are prevalent in developing countries, whereas certain CUPs dominate in North America and Europe. OCP levels are declining world wide. Concentrations from the XAD-based PAS agreed with those from polyurethane foam (PUF) disk PAS within a factor of 4 for most sites. The comparison revealed that the sampling rate of the PUF-based PAS is more dependent on wind speed, whereas that of the XAD-PAS has a higher dependence on temperature. Analysis of PAS deployed across arid, subtropical Botswana showed that recent use has more impact on present day air concentrations than historical use. Year-long measurements by high volume air sampling in Botswana yielded higher HCB levels in winter, and higher endosulfan levels in summer. Those variations are neither related to temperature fluctuation nor seasonal hydrological events, and are therefore more likely caused by pesticide usage pattern. Very low levels of OCPs were found in the warm, dry, low organic matter soils of Botswana, including in soils from historical use areas. Such soils appear to have a low long-term storage capacity for pesticides allowing for rapid volatilization. They are thus not long-term sources of pesticides to the atmosphere. Endosulfan sulfate levels were observed to increase in tropical soils with increasing elevation. Water samples from high altitude cloud forests in Costa Rica contained very low concentrations of CUPs and it is unlikely that that those levels pose a threat to amphibians in cloud forests. Laboratory experiments and literature analysis showed that the inert gas stripping method for the determination of air-water partitioning equilibria is susceptible to surface sorption artifacts for chemicals with a interface-air partition coefficient log (KIA/m) > -3. Using larger bubbles reduces the surface-to-volume ratio and produces accurate air-water partition coefficients for chemicals with log (KIA/m) < -1.2.

Phthalates have been used pervasively as plasticizers in consumer products and building materials. These semi-volatile organic compounds (SVOCs) are ubiquitous in indoor environments, redistributing from their original sources to indoor air, and subsequently to all interior surfaces. Because they partition strongly to surfaces, most phthalates persist for years after the source is removed. Biomonitoring data based on blood and urine testing provide direct evidence of the universal and significant human exposure to phthalates, which may result in serious adverse health effects. However, effective strategies to limit exposures to phthalates remain hamstrung by our poor understanding of their sources and fate and transport in indoor environments. The goal of this research is to explicitly elucidate the fundamental mechanisms governing emission, transport, and human exposure associated with phthalates in indoor environments. The specific research objectives are to 1) develop a novel, rapid, small-chamber method to determine the key parameters that control phthalate emissions and characterize the emissions; 2) investigate the influences of temperature, air flow rate, and surface sorption on phthalate emissions via a series of controlled tests in small and large chambers; 3) develop and validate a new indoor fate and transport model for phthalates with consideration of particle dynamics and its effects on emission and sorption. This research, which connects emission measurements to chemical transport and exposure assessment, will explicitly elucidate the fundamental mechanisms governing emission, transport, and human exposure associated with phthalates in indoor environments. / text