Background Concentrations of Polycyclic Aromatic Hydrocarbons and Heavy Metals in Florida Urban Soils.

Polycyclic aromatic hydrocarbons (PAHs) result from incomplete combustion or pyrolysis processes of organic matter and also can be released from petroleum products or coal. Generally, anthropogenic factors have the most impact on PAH distribution in urban areas, whereas natural factors affect their distribution in remote areas. These organic chemicals are ubiquitous and pose a risk for human health because of their potentially carcinogenic nature and availability in the environment that humans come in contact. Among all the environmental matrix, soil is the most important sink for PAHs. This is because PAHs are hydrophobic, semi-volatile, readily adsorbed by soil particles, and resist degradation. It has been estimated that approximately 90% of total residues remain in the soil. Therefore, investigate their background concentrations and source identifications in urban soils are necessary for better protecting the environment. In addition, heavy metals are also a problem in soils. At elevated concentrations, heavy metals are toxic to humans. Due to their non-biodegradable nature and long biological half-live of elimination from the body, their contamination in the environment is of concern. Heavy metals and PAHs often co-exist in contaminated soils, some of which have different chemical properties, modes of toxicity, and potential to interactions with soils. Exploration into the effects of metal mixtures has revealed that the toxicity of co-contaminants are not simple additions of individual toxicities. Non-additive toxicity is common and complicates attempts to address the risk assessment posed by environmental contamination of metal mixtures. It is even less clear when trying to assess the risks associated with mixtures of metals-PAHs. This study will discuss the background concentrations and distributions of PAHs and heavy metals in urban soils in Florida State.