|Lozano, Nuria - UNIV OF MD|
|Ramirez, Mark - DC WASA, WASHINGTON|
|Torrents, Alba - UNIV OF MD|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 12, 2009
Publication Date: July 26, 2009
Citation: Lozano, N., Rice, C., Ramirez, M., Torrents, A. 2009. Fate of triclocarban and triclosan in soils receiving biosolids applications. Meeting Abstract. 491. Technical Abstract: Triclosan (5-chloro-2-[2,4-dichloro-phenoxy]-phenol (TCS) and triclocarban (N-(4-chlorophenyl)-N’-(3,4-dichlorophenyl)urea) (TCC) are bactericidal compounds that are added to a wide range of household and personal care products such as hand soap, dish washing products, laundry detergents, cleaning wipes, toothpaste, deodorants and plastics. There is a growing concern about the discharge of these compounds from wastewater treatment plants onto the environment. It has been postulated that land application of biosolids could be a possible source since it has been suggested that about 90% of these compounds get removed from the water stream and get accumulated onto the sludge. Once released into the environment, these compound may undergo degradations, and can be transformed into other potentially toxic compounds, including methyl triclosan, dioxins, chloroform, and other chlorinated compounds. While it has been established that TCS and TCC are present in the biosolids, to date, little information is available on their distribution within biosolids and their fate upon land application. This study examines the concentration of TCC and TCS in biosolids collected from a WWTP periodically for over two years and their presence in soil samples collected from commercial farms in the Mid-Atlantic region which received zero, single and multiples applications of biosolids from the same source. In the biosolids leaving the plant, TCS and TCC concentrations were measured at mg/Kg d.w., with TCC concentrations running a little higher than the TCS concentrations. Our results suggest very little temporal variability. Concentrations of these compounds in the soils were much lower, levels in the ng/g d.w. range. Fields receiving biosolids applications always resulted in higher levels of the compounds than in the non-treated sites with the TCC concentrations typically higher than TCS in all soils. In an effort to assess build up of these compounds upon multiple applications, we evaluated the compound’s soil half life. Our results suggest that levels of TCC were significant even two years after application, levels of TCS went to background levels and no buildup is expected upon multiple applications. While build-up is expected for TCC, our results also illustrated soil dissipation of this compound. Our results also illustrated the presence of MeTCS at levels higher than in the biosolids, suggesting that TCS is being biodegraded in the soil.