Dissolved organic carbon as the main carrier of phthalic acid esters in municipal landfill leachates

Abstract

Various plastic materials have been disposed of in municipal waste dumps. Thus, phthalic acid esters (PAE) which are used as plasticizers can also be found in the leachates of those land fills. A number of leachates were divided into dissolved and particulate phases to determine the percentage of PAE being transported in the solution. The solutions were found to be contaminated with bis-(2-ethylhexyl) phthalate (DEHP) up to 235.9 μg l^-1, and dibutyl phthalate (DBP) at a maximum of 62.7 μg l^-1. Suspended particles contained maximum concen trations of 167.6 μg g ^-1 and 126.0 μg g^-1 for DEHP and DBP, respectively. Approximately 85% of the total PAE and a mean of 87% of the hydrophobic DEHP was detected in the dissolved phase. The amounts of PAE, especially of DEHP, in solution was correlated to dissolved organic carbon (DOC) concentrations. Moreover, there was a negative correlation of the contents of suspended solids with PAE in dissolved form. The results mdicate that in municipal landfill leachates the DOC is much more important as a transport vehicle for hydrophobic phthalate esters than the suspended particles present. Consequently, there may be a much higher mobilis ing potential for codisposed environmental chemicals than supposed so far.