Biodegradation in Contaminated Aquifers: Incorporating Microbial/Molecular Methods

Abstract

In order to evaluate natural attenuation in contaminated aquifers, there has been a recent recognition that a multidisciplinary approach, incorporating microbial and molecular methods, is required. Observed decreases in contaminant mass and identified footprints of biogeochemical reactions are often used as evidence of intrinsic bioremediation, but characterizing the structure and function of the microbial populations at contaminated sites is needed. In this paper, we review the experimental approaches and microbial methods that are available as tools to evaluate the controls on microbially mediated degradation processes in contaminated aquifers. We discuss the emerging technologies used in biogeochemical studies and present a synthesis of recent studies that serve as models of integrating microbiological approaches with more traditional geochemical and hydrogeologic approaches in order to address important biogeochemical questions about contaminant fate.

Description and Verification of the Contaminat Transport Models in Groundwater (Theory And Practice)

“…This above-mentioned remark can be noticed by Spitz and Moreno [9], Zheng and Wang [14], Chiang [3], Javadi and AL-Najjar [4], Weiss and Cozarelli [12], Joekar-Niasar et al [5], Zhang et al [13]. So, taking into consideration the above-mentioned remarks and substituting equation (12) into equation (11), equation (11) can be rearranged and written as: k the fi rst-order reaction rate for the kinetically-controlled biodegradation process (biological denitrifi cation) for both the dissolved (aqueous) and the sorbed (solid) phases [s -1 ] .…”

“…This regularity is related even to the similar (but never the same) contaminants moving in ground media (Spitz and Moreno [9], Chiang [3], Javadi and AL-Najjar [4], Weiss and Cozzarelli [12], Kraft et al [7], Aniszewski [1], Taniguchi and Holman [11], Aniszewski [2]). This is connected, among other things, with negative or positive charging of the solid phase of natural soils (as an "anionic" or "cationic" exchange) (Spitz and Moreno [9], Chiang [3], Javadi and AL-Najjar [4], Weiss and Cozzarelli [12], Kraft et al [7], Taniguchi and Holman [11]). It should also be noted that in various climatic and ground conditions, physico-chemical and biological properties of moving groundwater differ considerably one from another, impacting on all the major processes (parameters) used in the transport models and presented here.…”

“…It should also be noted that in various climatic and ground conditions, physico-chemical and biological properties of moving groundwater differ considerably one from another, impacting on all the major processes (parameters) used in the transport models and presented here. The climatic and ground conditions selected for the presented transport models are described in greater detail by Spitz and Moreno [9], Chiang [3], Weiss and Cozzarelli [12], Kraft et al [7], Aniszewski [1], Taniguchi and Holman [11] and Aniszewski [2].…”

Subsurface Cycling of Nitrogen and Anaerobic Aromatic Hydrocarbon Biodegradation Revealed by Nucleic Acid and Metabolic Biomarkers

“…Whenever possible, strategies for documenting biogeochemical change involve mass balance approaches that quantitatively link materials subject to a given metabolic process (e.g., consumption of carbon substrates) to formation of metabolic by-products (e.g., CO 2 ). However, owing to the open nature of many natural systems (including ocean water, rivers, and soils), convergent lines of evidence obtained using a variety of approaches (e.g., model incubations, analytical chemistry of metabolites, and molecular biology of genes and mRNA) are often needed to understand site biogeochemistry (40,46,71). Direct detection of mRNA in environmental samples has increasingly become an effective approach for documenting the in situ biogeochemical activity of microbial communities in field sites (33,34,42).…”

In Silico Geobacter sulfurreducens Metabolism and Its Representation in Reactive Transport Models

“…Their activities affect the physicochemical nature of the local environment, drive elemental cycling, and determine the fate of many contaminants (9,49). Effects can be direct (for example, by altering the local chemical composition through the utilization of substrates and terminal electron acceptors for energy production and growth or cometabolism) or indirect (for example, by affecting the presence and the chemical nature of solid iron phases, which determines sorption and coprecipitation of transition metals and contaminants) (4,6,17,51).…”