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Beneficial reuse as an alternative to disposal is increasingly being considered in management of contaminated sediments dredged from harbors. The risk of metal leaching into groundwater in reuse of phosphate and thermal treated sediments was assessed with sequential extraction, synthetic precipitation leaching procedure (SPLP), and leaching as a function of pH and liquid to solid ratio (L/S). Sequential extraction revealed that phosphate addition at 5% by dry weight, followed by calcination at 700[degrees]C reduced metal association with exchangeable/carbonate and organic phases and increased that with sparingly soluble residuals. Over the pH range 4 to 9, metal leachability varied by two to four orders of magnitude while varying L/S over 5 to 100 showed little difference. The SPLP revealed that risk to groundwater criteria based on applying a dilution attenuation factor (DAF) of 13 (New Jersey) to groundwater quality levels were achieved. Risk criteria based on a DAF of 1 (Florida and Wisconsin) were exceeded for Pb, Cd, and Mn; thermodynamic analysis demonstrates that the criteria cannot be satisfied should dissolution control pore water concentrations. DOI: 10.1061/(ASCE)EE. 1943-7870.0000164 CE Database subject headings: Heavy metals; Groundwater quality; Heat treatment; Leaching; Phosphate; Lead; Groundwater pollution; Sediment. Author keywords: Heavy metals; Groundwater quality; Heat treatment; Leaching; Lead; Pollution; Sediment; SPLP.

Abstract: Motor vehicle traffic is an important source of particulate pollution in cities of the developing world, where rapid growth, coupled with a lack of effective transport and land use planning, may result in harmful levels of fine particles (PM2.5) in the air. However, a lack of air monitoring data hinders health impact assessments and the development of transportation and land use policies that could reduce health burdens due to outdoor air pollution. To address this important need, a study of traffic-related PM2.5 was carried out in the city of Nairobi, Kenya, a model city for sub-Saharan Africa, in July 2009. Sampling was carried out using portable filter-based air samplers carried in backpacks by technicians on weekdays over two weeks at several sites in and around Nairobi ranging from high-traffic roadways to rural background. Mean daytime concentrations of PM2.5 ranged from 10.7 at the rural background site to 98.1μg/m3 on a sidewalk in the central business district. Horizontal dispersion measurements demonstrated a decrease in PM2.5 concentration from 128.7 to 18.7μg/m3 over 100m downwind of a major intersection in Nairobi. A vertical dispersion experiment revealed a decrease from 119.5μg/m3 at street level to 42.8μg/m3 on a third-floor rooftop in the central business district. Though not directly comparable to air quality guidelines, which are based on 24-h or annual averages, the urban concentrations we observed raise concern with regard to public health and related policy. Taken together with survey data on commuting patterns within Nairobi, these results suggest that many Nairobi residents are exposed on a regular basis to elevated concentrations of fine particle air pollution, with potentially serious long-term implications for health. [Copyright &y& Elsevier]