Lead in New Orleans soils: New images of an urban environment

Abstract

This paper describes a survey of lead in soil and computer generated maps that have been derived for New Orleans, Louisiana. The soil survey included streetside, houseside and open space samples. Because the survey covered every census tract in the metropolitan area it was possible to construct a computer-generated map of the distribution of lead dust in the soils of the urban environment. The data base consists of coordinates, site characteristics and lead analytical results of 3,704 soil samples. The resulting graphics show peaks of lead ranging from 600-1,200 μg per g in the streetside soil of the inner-city and a steeply declining slope to the suburban areas of the city where the lead content of streetside soils is less than 75 μg/g. In the inner-city, the amount of lead in soils found near building foundations is 10 to 20 times higher than the soils adjacent to streets where the median lead content of soils is over 300 μg g(-1). In areas surrounding the city core ("mid-city"), the amount of lead next to the foundation and adjacent to the street are equivalent with medians of 110 μg g(-1). In suburban locations, the median lead content of soil along streetsides is 86 μg g(-1). Soils adjacent to surburban foundations has a median Pb content of 50 μg g(-1). The lowest median lead content in soil is found in open spaces, ranging from 212 to 40 to 28 μg g(-1), respectively, for the inner-city, mid-city, and suburbs. These observations are consistent with the production and consumer use of lead-based paint and leaded-fuels within the modern city.