PERSISTENCE OF ORGANIC CONTAMINANTS IN SEWAGE SLUDGE-AMENDED SOIL - AFIELD EXPERIMENT

Digested sludge was applied to plowed arable and pasture grassland plo ts and losses of specific volatile organic compounds (VOCs), polychlor inated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), po lychlorinated dibenzofurans (PCDFs), and chlorophenols (CPs) monitored over 260 d, Sludge addition increased soil concentrations of all comp ounds in the plowed plot, VOCs, PCBs, and CPs concentrations declined to control plot values within 128 d of sludge amendment, Volatilizatio n and biodegradation were considered important loss processes for thes e compounds. However, PCDD/F and of non-o-PCB 77 concentrations did no t change consistently and remained elevated above control plot concent rations throughout the monitoring period. At Day 260 410 +/- 53 ng Sig ma PCDD kg(-1) and 250 +/- 10 ng Sigma PCDF kg(-1) was detected in the sludged plot compared to 68 +/- 9 ng Sigma PCDD kg(-1) and 170 +/- 7 ng Sigma PCDF kg(-1) in the control plot, Data from the pasture plot h as highly variable and differences between most contaminant concentrat ions in the sludged and control plots were insignificant, This was att ributed to adherence of much of the applied sludge to vegetation rathe r than direct application to the soil surface and has important implic ations for elevated dietry intake of certain persistent organic compou nds such as the PCDD/Fs, Further research is needed to evaluate the im portance of sludge adherence to vegetation for human exposure to a ran ge of contaminants detected in sludge, Contaminant movement to depth ( 20 cm) was not detected within 260 d for compounds monitored (VOCs and PCDD/Fs).