Environ. Sci. Technol. 2004, 38, 632-637
Combined Bioaugmentation and Biostimulation To Cleanup Soil Contaminated with High Concentrations of Atrazine ELISABETE SILVA,† ARSE ´ NIO M. FIALHO,† ISABEL SA ´ -CORREIA,† R I C H A R D G . B U R N S , ‡ A N D L I Z J . S H A W * ,‡ Biological Sciences Research Group, Centre for Biological and Chemical Engineering, Instituto Superior Te´cnico, Lisbon, Portugal, and Research School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, U.K.
We developed a joint bioaugmentation and biostimulation approach for the clean up of soil contaminated with high (168.7 and 337.4 µg g-1) concentrations of the herbicide atrazine (2-chloro-4-(ethylamino)-6-isopropylamino-striazine). Pseudomonas sp. strain ADP (P. ADP) was used for bioaugmentation (∼107 cells g-1 soil), and citrate (concentration range 5.8-40 mg g-1 soil) and succinate (6.230.8 mg g-1) were used for biostimulation. The study soil had indigenous potential for atrazine mineralization (54.4 ( 2% of 168.7 µg g-1 mineralized after 67 day), but rapid mineralization only took place after a prolonged acclimation phase (∼28 days). Inoculation with P. ADP alone resulted in a limited improvement in mineralization (e.g., 30.6 ( 1% mineralization of 168.7 µg g-1 of atrazine in inoculated soil cf. 95%, radiochemical purity > 98%, specific activity ) 558.7 MBq mmol-1), trisodium citrate (>99%), and sodium succinate (>99%) were purchased from Sigma Chemical Co. Soil. A silty clay loam soil (pH 5.3; organic matter content 2.8%; cation exchange capacity 23.4 meq 100 g-1 (33)) was used for all experiments. Microbial properties (biomass C and enzyme activities) for this soil have been reported elsewhere (33). Soil had been tilled conventionally and cropped with annual rotations of soybean and maize. Soil was collected from the surface (0-30 cm), sieved (
