Evaluating a bioremediation tool for atrazine contaminated soils in open soil microcosms: The effectiveness of bioaugmentation and biostimulation approaches

Abstract

A previously developed potential cleanup tool for atrazine contaminated soils was evaluated in larger open soil microcosms for optimization under more realistic conditions, using a natural crop soil spiked with an atrazine commercial formulation (Atrazerba FL). The doses used were 20x or 200x higher than the recommended dose (RD) for an agricultural application, mimicking over-use or spill situations. Pseudomonas sp. strain ADP was used for bioaugmentation (around 10(7) or 10(8) viable cells g(-1) of soil) and citrate for biostimulation (up to 4.8 mg g(-1) of soil). Bioremediation treatments providing fastest and higher atrazine biodegradation proved to differ according to the initial level of soil contamination. For 20x RD of Atrazerba FL, a unique inoculation with Pseudomonas sp. ADP (9 +/- 1 x 10(7) CFU g(-1)) resulted in rapid atrazine removal (99% of the initial 7.2 +/- 1.6 microg g(-1) after 8d), independent of citrate. For 200x RD, an inoculation with the atrazine-degrading bacteria (8.5 +/- 0.5 x 10(7) CFU g(-1)) supplemented with citrate amendment (2.4 mg g(-1)) resulted in improved biodegradation (87%) compared with bioaugmentation alone (79%), even though 7.8 +/- 2.1 microg of atrazine g(-1) still remained in the soil after 1 wk. However, the same amount of inoculum, distributed over three successive inoculations and combined with citrate, increased Pseudomonas sp. ADP survival and atrazine biodegradation (to 98%, in 1 wk). We suggest that this bioremediation tool may be valuable for efficient removal of atrazine from contaminated field soils thus minimizing atrazine and its chlorinated derivatives from reaching water compartments.

Biostimulation for the Enhanced Degradation of Herbicides in Soil

“…Lima et al [88] successfully transferred a previously examined "small-scale biostimulation strategy" of atrazine to a larger open soil conditions spiked with commercial formulation at doses, mimicking overuse or concentration "hot spots" that may arise from the uneven application and spill scenarios. In another field evaluation experiment, Strong et al [89] assessed a range of biostimulation supplements to optimize the nutritional additives and applied this information to the field to test systematically the ability of different bioremediation methods to remediate soil heavily contaminated with atrazine by an accidental spill.…”

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“…On the other study of Agrobacterium radiobactor strain J14a, the degradation rate of atrazine was enhanced in Sequential Batch Biofilm Reactor (SBBR) after the additional supply of carbon source (Protzman et al, 1999). Bioaugmentation of Pseudomonas strain was found to be an encouraging indigenous treatment for atrazine spilled at high concentrations in soil (Lima et al, 2009). Rousseaux et al (2003) observed a 3-fold increase in biodegradation capacity after the bioaugmentation of 10 4 CFU g -1 of Chelatobacter heintzii Cit1 in the soil.…”

Simultaneous Determination of Selected Insecticides and Atrazine in Soil by Mae–GC–ECD

“…The lowest value of LOD (0.188 ng/g) was obtained by means of LC -MS/MS by Jablonowski [20]. Gas chromatography with nitrogen -phosphorus detector provides limit of detection around 0.005 mg/L [35], 1.5 ng/g -2 ng/g [3,5,9,15,32] while with mass detector 0.3 μg/L, 4 ng/g -8,3 ng/g [ 9,23,24,25,33,36].…”