Behavior of Aromatic Surfactants and PCBs in Sludge-Treated Soil and Landfills

The aromatic surfactant linear alkylbenzenesulphonate (LAS) and the refractory biointermediates of nonylphenol polyethoxylates (NPEO), namely nonylphenol (NP), nonylphenol monoethoxylate (NP1EO) and nonylphenol diethoxylate (NP2EO), together with polychlorinated biphenyls (PCBs) and organic carbon (OC), were determined in sludge-treated soil at 19 time intervals during a 1-yr period after sludge application. The initial concentrations of LAS, NP, NP1EO, and NP2EO in the amended soil were 45, 4.7, 1.1 and 0.1 mg/kg (dry wt.); the residual mean concentrations, 320 d after the last sludge application, were 5, 0.5, 0.1, and 0.01 mg/kg for LAS, NP, NP1EO, and NP2EO, respectively. All of the aromatic surfactants demonstrated a very fast decrease in concentration (>80% within the first month), presumably due to biodegradation, but all of them exhibited a residual concentration in the soil after 320 d. Total PCBs and OC showed no significant soil concentration changes, within the error of analysis, over this same 1-yr period. The pattern of PCB congeners also demonstrated no substantial changes, indicating that they all behave very similarly. The LAS and PCBs were also measured in samples from dated ponds of four sludge-only landfills which were in use at different times over the past 30 yr. The increase in the use of LAS and decrease in the open use of PCBs was reflected in the sludge pond concentrations at one site where there was a continuous record from 1972 to 1986.