Fractosphere, the Site of Hydrogeological-microbial Interaction: Current and Future Perspectives.

Abstract

Beneath the base of gas-hydrate stability (BGHS), gas-hydrate is disintegrated into gas and water that form an \"unsatd. zone\". Some gas-hydrate belts are located in the plate convergent margins, where fluid flows in the sub-BGHS unsatd. zones may have hydrogeol. relevance. The fluid flow in unsatd. zone has a complicated mechanism due to flows in both gas and liq. phases, and hydraulic interaction (exchange of water) between the fracture and matrix. Furthermore, the formation of biofilms on fracture surfaces possibly alters the hydraulic properties of fractured rock masses. For accurate evaluation of macroscopic hydraulic properties of an unsatd. fractured rock system, a lab. expt. was performed using two rock blocks with a single-fracture in-between. Absorption of a part of the water flowing through the fracture was exptl. measured and quant. evaluated by a single parameter, \"sorptivity\". Some microorganisms were cultured in the lab. to form biofilms on the rock surface and some colonized in intergrain micro-cracks. Based on theor. considerations, we also hypothesize the potential for biofilm-forming microorganisms to alter macroscopic hydraulic properties of unsatd. fractured rock masses. [on SciFinder (R)]