A source mixing model to apportion PAHs from coal tar and asphalt binders in street pavements and urban aquatic sediments
Documentos PDF
Imagenes y Videos
Abstract
Present-day and more than 30 years old road and footpath pavements from Auckland, New Zealand were
analysed for PAHs to test the hypothesis that coal tar based pavement binders contribute to unusually
high PAH concentrations in adjacent stream and estuarine sediments. Total PAH (P28PAH) concentrations in the dichloromethane-soluble fraction (‘‘binder”), comprising 5–10% of pavement mass, were as
high as 200 000 mg kg1 (10 000 mg kg1 in binder + aggregate). Older and deeper pavement layers were
strongly pyrogenic, whereas pavement layers from recently sealed roads had a more petrogenic composition and more than 1000 times lower P28PAH concentrations. Source identification analysis using three
PAH isomer ratio pairs (benz(a)anthracene/(benz(a)anthracene + chrysene); benzo(a)pyrene/(benzo(a)-
pyrene + benzo(e)pyrene); and indeno(1,2,3-cd)pyrene/(indeno(1,2,3-cd)pyrene + benzo(g,h,i)perylene)
revealed low PAH (bitumen) pavements to have consistently lower isomer ratios than high PAH (coal
tar) samples. Moreover, pavement data for one isomer ratio (e.g. benzo(a)pyrene/(benzo(a)pyrene + benzo(e)pyrene) were highly correlated with those of another isomer ratio (e.g. benz(a)anthracene/
(benz(a)anthracene + chrysene) and were bounded at their lower and higher extremes by the characteristics of pure bitumen and coal tar, respectively, suggesting that PAH composition of a given pavement
sample could be accounted for by conservative mixing between coal tar and bitumen as source materials.
A concentration-weighted mixing model, with coal tar and bitumen as source materials, explained more
than 80% of the variance in isomer ratios and enveloped the entire PAH compositional and concentration
range encountered. PAH composition and concentrations in adjacent stream sediments (> 15 mg kg1 dry
weight) were consistent with diluted coal tar material as a principal PAH source. Due to the very high
PAH concentrations of coal tar, a coal tar content of as little as 0.01% of total sediment mass can account
for more than 90% of PAH concentrations in adjacent stream sediments.
Palabras clave
PAH; Pavement; Coal tar; Bitumen; Source identification; Isomer ratioLink to resource
https://doi.org/10.1016/j.chemosphere.2010.08.030Collections
- Año 2010 [81]
Estadísticas Google Analytics
Comments
Respuesta Comentario Repositorio Expeditio
Gracias por tomarse el tiempo para darnos su opinión.