Effect of different nutrient sources in the bioremediation of soils chronically contaminated with hydrocarbons at Carlini station, Isla 25 de mayo, South Shetland Islands, Antarctica

VILLALBA PRIMITZ JER; VAZQUEZ S.; RUBERTO L.; HERNANDEZ E.; COLMAN D; LO BALBO A; MAC CORMACK W.

Congreso; XII Congreso Argentino de Microbiología General SAMIGE; 2017

The logistics involved in the operation of Antarcticstations and the development of scientific activities entail the risk ofcontamination by fuels. Previous studies have shown that biostimulation ofsoils chronically contaminated with Antarctic Gasoil (AGO) produces significantincreases in the removal of hydrocarbons (HC). In this work, we report on theeffect of amendment with N and P in different formulations: inorganic salts, NH4NO3y Na2HPO4, with (IN) and without (ANA) oxygenation by mixing; Nitrofoska® granularfertilizer (NPK) and OSEII® commercial product (CP), on the efficiency of HCremoval from soils with chronic contamination by gasoil, compared to a systemwithout nutrient addition (CC). The soil was collected from an area affected bythe dripping of a connection between two diesel fuel pipes. Treatments were donein triplicate, simulating biopiles containing 15 kg of soil, which were sampledover 50 days, analyzing the changes in the bacterial communities involved andthe quality and quantity of the remaining HC. Total heterotrophic aerobic (THAB)and hydrocarbon degrading bacteria (THDB) counts were performed on CPS agar andGasoil agar. The quantification of hydrocarbons was performed by infrared spectrophotometry(modified ASTM D066 method) and by GC-FID. The V3-V4 region (GC-341F and 518Rprimers) of the 16S rRNA gene was partially amplified in all soil samples toobtain a fingerprinting of the bacterial communities by DGGE (45% -60% denaturingurea/formamide gradient, gels run at 60V and 65 °C for 16h). Both the presence ofnumerous bacterial populations and changes in their relative proportions in thecommunity throughout the trial as well as the decrease in HC concentration inCC systems indicate that, even without nutrient aggregation, the nativemicrobiota can metabolize HC with just aerating the soil and at the expense ofthe few available nutrients. However, biostimulated systems resulted inmarkedly higher HC removal with respect to CC, with CP as the most efficient. Bacterialcounts supported these results, showing a greater proportion of degradingpopulations in biostimulated systems. With respect to the communities involved,although it is expected that any intervention in the microenvironment of microorganismswill influence its structure, particularly the aggregate of inorganic salts(IN, ANA) and granular fertilizer (NPK) selected communities less diverse thanin CC, while the addition of OSEII® (CP) product led to the development of morediverse communities. Although natural attenuation contributes to the removal ofHC in Antarctica, the activity of microorganisms plays a key role inaccelerating this process, which is important in Antarctica given the shortperiods in which the soils are thawed and accessible to carry out a treatment.The addition of nutrients to balance metabolism favors the biodegradation of HCand increases their removal in shorter times.