PAH and metal mixtures in New Orleans soils and sediments

The purpose of this study is to determine the degree of PAH contamination and the association of PAHs with inorganic substances in soils and sediments of New Orleans. Bonnet Carr´e Spillway ŽBCS. Žn 5. provides modern baseline data, while urban soil samples ŽCTY. Žn 27. and sediment samples from Bayou St. John ŽBSJ. Žn 11. provide experimental data for New Orleans. Soil samples were collected from the top 2.5 cm of the surface, air-dried, and sieved Ž2 mm.. Sediments samples were collected with a Wildco-Ekman bottom dredge, air-dried and finely ground. Accelerated solvent extraction ŽASE. was used to release PAHs from the samples and analysis was conducted with gas chromatography-mass spectrometry ŽGC-MS.. Metals were extracted using a 5:1 ratio of 1 mol L nitric acid Žroom temperature. for soil and sediment samples, shaken for 2 h, centrifuged Ž1000 g for 15 min. and filtered. Metal analysis was done by inductively coupled plasma-atomic emission spectrometry ŽICP-AES.. Mann Whitney tests show PAH differences ŽP 0.001.. Ranking of total PAHs is, BSJ sediments Ž10.3 mg kg. CTY soils Ž3.7 mg kg. BCS alluvium Ž0.28 mg kg.. The sum of the metals are similar for BSJ sediments Ž698 mg kg. and CTY soils Ž679 mg kg. and significantly lower for BCS Ž189 mg kg.. Manganese of these samples is similar for each site. For paired samples, Pearson Product Moment Correlation tests reveal that many PAHs are strongly associated with each other at all locations. For BCS alluvium and BSJ sediments, total PAHs are not significantly associated with total metals. For CTY, most pairs of metals are significantly associated, and total soil PAHs are strongly associated with total soil metals Žcorrelation 0.78, P 4.9 10 4 .. The linear model, total soil PAH 136.3 6.25 Žtotal soil metals. forms the basis for a predicted PAH map of New Orleans. Previous empirical research demonstrates an association between soil lead and children’s lead exposure. This study indicates that PAHs are part of the soil mixture of accumulated substances and by-products of industrial society that presents exposure potential in cities.