USE OF NEXT GENERATION SEQUENCING TO STUDY THE FEASIBILTY TO APPLY MONITORED NATURAL RECOVERY IN FRESHWATER SEDIMENTS AFFECTED BY ANCIENT HUMAN ACTIVITY

MADUEÑO L; COPPOTELLI B. M.; STAREVICH, V. A; TERADA C; NUCCETELLI D; VIDAL NC; ONETO ME; DEL PANNO M.T; MORELLI I. S.

Lyon

Congreso; 14th International Conference, Sustainable Use and Management of Soil, Sediment and Water Resources, AquaConSoil; 2017

The monitored natural recovery (MNR) is a remedial approach that relies on natural physical, chemical, and biological processes to reduce ecological and human health risks. MNR is a non-invasive technology which, carefully planned, allows remediation of sediment sites and can result in risk reduction in comparison with dredging and capping. The aim of this work was to evaluate the application of MNR from a freshwater course affected by human activity using sediments biological parameters and next generation sequencing methods (NGS) as potential indicators of biological processes. The studied sediments come from a freshwater course with history of involvement by oil pollution, and whose recovery began projecting over 20 years ago. 30 sediments cores distributed in 5 transects along the water channel were extracted using a Hammer Piston tool. Physicochemical variables (humidity, pH, depth, total sulfide, total nitrogen and phosphate), enzymatic activity (dehydrogenase, lipase, protease, phosphatase, protease and aril-sulfatase) and Total Petroleum (TNRCC 1005), Aliphatic and Aromatic Hydrocarbons (TNRCC 1006) were determined at the different horizons found in each core. The hydrocarbons concentration was also determined in the water samples corresponding to the each core site. The bacterial and archaea diversity was determined by NGS (Illumina). Canonical correspondence analysis (CCA) between biodiversity and environmental variables were performed using the software Canoco version 4.5. The water samples showed hydrocarbons concentration below de detection limit. In all studied cores could be differentiated a surface horizon, called H0, that showed the lowest or not detectable hydrocarbons concentrations and highest biodiversity index, dominated by Deltaproteobacteria, Actinobacteria, Anaerolinea and Methanobacteria classes. Hydrocarbons concentration increased and bacterial diversity decreased in deep horizons, characterized by a remarked dominance of Gammaproteobacteria and Bacilli classes.CCA axes between bacterial community composition and physicochemical variables or enzymatic activities, explained respectively 42.6% and 46.3% of the total variance in community composition and 72.1% and 73.6% of the cumulative variance of the species?environment relationship. Spatial distribution of the communities correlated significantly (P0.05, F=1.25). The bacterial community of H0 showed a positive correlation with total nitrogen, humidity and lipase, protease, urease and alkaline phosphatase activities, suggesting that these horizons were characterized by their activity in recycling nutrients.The great bacterial diversity and enzymatic activities detected in the H0 allow us to infer the presence of a natural ?biofilter? able to process the organic matter, contributing to the pollutant degradation, confining it to the deepest horizons and preventing the hydrocarbons reentry to the watercourse; indicating that MNR would be a sustainable option for the recovery of this site.