Groundwater geochemistry and microbial community structure in the aquifer transition from volcanic to alluvial areas

Groundwaters may act as sinks or sources of organic and inorganic solutes, depending on the relative magnitude of biochemical mobilizing processes and groundwater-surface water exchanges. The objective of this study was to link the lithological and hydrogeological gradients to the aquatic microbial...

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Bibliographic Details
Published in:	Water research (Oxford) 2014-11, Vol.65, p.384-394
Main Authors:	AMALFITANO, S, DEL BON, A, ZOPPINI, A, GHERGO, S, FAZI, S, PARRONE, D, CASELLA, P, STANO, F, PREZIOSI, E
Format:	Article
Language:	eng
Subjects:	Alluvial deposits Animal and plant ecology Animal, plant and microbial ecology Aquifers Archaea - isolation & purification Bacteria - isolation & purification Biological and medical sciences Communities Concentration (composition) Enterobacteriaceae - isolation & purification Escherichia coli Estimating Freshwater Fundamental and applied biological sciences. Psychology Geochemistry Geologic Sediments - chemistry Groundwater Groundwater - chemistry Groundwater - microbiology Italy Microbial ecology Microorganisms Particular ecosystems Synecology Various environments (extraatmospheric space, air, water) Water Movements
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Summary:	Groundwaters may act as sinks or sources of organic and inorganic solutes, depending on the relative magnitude of biochemical mobilizing processes and groundwater-surface water exchanges. The objective of this study was to link the lithological and hydrogeological gradients to the aquatic microbial community structure in the transition from aquifer recharge (volcanic formations) to discharge areas (alluvial deposits). A field-scale analysis was performed along a water table aquifer in which volcanic products decreased in thickness and areal extension, while alluvial deposits became increasingly important. We measured the main groundwater physical parameters and the concentrations of major and trace elements. In addition, the microbial community structure was assessed by estimating the occurrence of total coliforms and Escherichia coli, the prokaryotic abundance, the cytometric and phylogenetic community composition. The overall biogeochemical asset differed along the aquifer flow path. The concentration of total and live prokaryotic cells significantly increased in alluvial waters, together with the percentages of Beta- and Delta-Proteobacteria. The microbial propagation over a theoretical groundwater travel time allowed for the identification of microbial groups shifting significantly in the transition between the two different hydrogeochemical facies. The microbial community structure was intimately associated with geochemical changes, thus it should be further considered in view of a better understanding of groundwater ecology and sustainable management strategies.
ISSN:	0043-1354 1879-2448