Are dominant microbial sub-surface communities affected by water quality and soil characteristics?

Abstract

Subsurface microorganisms must deal with quite extreme environmental conditions. 13The lack of light, oxygen, and potentially nutrients are the main environmental stresses 14 faced by subsurface microbial communities. Likewise, environmental disruptions 15 providing an unbalanced positive input of nutrients force microorganisms to adapt to 16 varying conditions, visible in the changes in microbial community diversity. In order to 17 test microbial community adaptation to environmental changes, we performed a study 18 in a surface Managed Aquifer Recharge facility, consisting of a settlement basin (two-19 day residence time) and an infiltration pond. Data on groundwater hydrochemistry, soil 20 texture, and microbial characterization was compiled from surface water, groundwater, 21 and soil samples at two distinct recharge operation conditions. 22Multivariate statistics by means of Principal Component Analysis (PCA) was the 23 technique used to map the relevant dimensionality reduced combinations of input 24 variables that properly describe the system behavior. The methodology selected allows 25 including variables of different nature and displaying very different range values. Strong 26 differences in the microbial assemblage under recharge conditions were found, 27 coupled to hydrochemistry and grain-size distribution variables. Also, some microbial 28 groups displayed correlations with either carbon or nitrogen cycles, especially showing 29 *Manuscript Click here to view linked References abundant populations of denitrifying bacteria in groundwater. A significant correlation 30 was found between Methylotenera mobilis and the concentrations of NO 3 and SO 4 , and 31 also between Vogesella indigofera and the presence of DOC in the infiltrating water. 32 Also, microbial communities present at the bottom of the pond correlated with 33 representative descriptors of soil grain size distribution. 34 , 2009). Actually, the unsaturated zone, and more specifically the topsoil, 39 supports the highest microbial activity and biomass of all compartments within the 40 subsurface environment (Lapworth et al., 2012). Likewise, microorganisms are 41 responsible for most biological processes in aquifers (Stein et al., 2010). 42 LuedersSeveral studies evidence microbial adaptation to groundwater extreme environments 43 (thermal or hypersaline) (e.g., Rothschild and Mancinelli, 2001) or disturbed by human 44 activities (Meckenstock et al., 2015). Human activities have caused disruption in 45 aquifer dynamics to some extent (Griebler and Lueders, 2009;, with 46 biological implications as indigenous microorganisms can acclimate (Pett-Ridge and 47Rodriguez-Escales and Sanchez-Vila, 2016), (2) determining the physical and 56 hydrochemical conditions that can govern the behavior of specific microbial groups 57

High diversity and heterogeneity define microbial communities across an active municipal landfill

“…In comparison, there were no significant differences among our samples, however, GW1 showed lower richness and overall phylogenetic distance than the other samples, but similar evenness with GW2. The alpha diversity of these groundwater wells is greater than has been reported for other groundwater aquifers, with Shannon Index values below 4 and as low as 0.47 having been reported for some [29,30]. The landfill leachate well and composite leachate cistern sample diversities are consistent with the findings of Stamps et al (2016), who showed high richness and evenness across the 19 U.S. landfills in their study.…”

Modeling the fate of UV filters in subsurface: Co-metabolic degradation and the role of biomass in sorption processes

“…In all cases, the biological processes are very active and many redox reactions are occurring simultaneously (Greskowiak et al, 2006). This phenomenon is enhanced in recharge applications, e.g., by the presence of a reactive layer of organic matter (Beganskas et al, 2018;Grau-Martínez et al, 2017;Valhondo et al, 2014), that could lead to biomass growth and bioclogging (Barba et al, 2019;Massmann et al, 2006;Perujo et al, 2018). Besides this, recharge processes are a relevant source of EOCs (here including UVFs) into aquifer systems (Kim et al, 2017;Laws et al, 2011;Maeng et al, 2011;Park and Lee, 2018).…”

What are the main factors influencing the presence of faecal bacteria pollution in groundwater systems in developing countries?

“…Multivariate statistics is a suitable technique to treat big datasets involving different sorts of variables, from quantitative to categorical, and thus amenable to be used to combine biochemical, hydraulic, geological and external conditions (such as design, drilling characteristics. and maintenance) of water points (Barba et al, 2019b). Principal Component Analysis (PCA) is a multivariate statistics method which involves the analysis of a number of parameters or variables, revealing associations between them, known as (vario)factors or components.…”

“…For this reason, some variables from the initial dataset were grouped, transformed and/or eliminated. Following Barba et al, (2019b), non-Gaussian hydrochemical variables were transformed to log concentrations, these being Alkalinity, Eh (a proxy for redox conditions), and the concentrations of SO4 2-, Na + , Cl -, and SiO2. On the other hand, TOC (Total Organic Carbon), DO (Dissolved Oxygen), and the concentrations of NO3and NH4 + , were added to the analysis as raw data without any transformation (mostly based on a trial and error basis).…”