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104. Scaling down hyporheic exchange flows: from catchments to reaches.

Author

Magliozzi, Chiara, Grabowski, Robert, Packman, Aaron I., and Krause, Stefan

Abstract

Rivers are not isolated systems but continuously interact with the subsurface from upstream to downstream. In the last few decades, research on the hyporheic zone (HZ) from many perspectives has increased appreciation of the hydrological importance and ecological significance of connected river and groundwater systems. Although recent reviews, modelling and field studies have explored hydrological, biogeochemical and ecohydrological processes in the HZ at relatively small scales (bedforms to reaches), a comprehensive understanding of the factors driving the hyporheic exchange flows (HEF) at larger scales is still missing. To date, there is fragmentary information on how hydroclimatic, hydrogeologic, topographic, anthropogenic and ecological factors interact to drive hyporheic exchange flows at large scales. Further evidence is needed to link hyporheic exchange flows across scales. This review aims to conceptualize interacting factors at catchment, valley and reach scales that control spatial and temporal variations in hyporheic exchange flows. The implications of these drivers are discussed for each scale, and co-occurrences across scale are highlighted in a case of study. By using a multi-scale perspective, this review connects field observations and modelling studies to identify broad and general patterns of HEF in different catchments. This multi-scale perspective is useful to devise approaches to interpret hyporheic exchange across multiscale heterogeneities, to infer scaling relationships, and to inform watershed management decisions. [ABSTRACT FROM AUTHOR]

Published
2017
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105. Biomineralization strongly modulates the formation of Proteus mirabilis and Pseudomonas aeruginosa dual-species biofilms.

Author

Xiaobao Li, Nanxi Lu, Brady, Hannah R., and Packman, Aaron I.

Subjects
BIOMINERALIZATION, PROTEUS (Bacteria), PSEUDOMONAS aeruginosa, BIOFILMS, URINARY tract infections
Abstract

Proteus mirabilis and Pseudomonas aeruginosa are common pathogens that often form biofilms together in catheter-associated urinary tract infections (CAUTI). However, the interactions between these two species in biofilms are largely unknown. Proteus mirabilis induces ureolytic biomineralization that substantially modifies key biofilm properties including morphology, persistence and recalcitrance to antimicrobial therapy. These processes are well known to complicate CAUTI, but the consequences for colonization and persistence of P. mirabilis in polymicrobial biofilms have not been explored. Here, we characterized the role of biomineralization in regulating the development of P. mirabilis and P. aeruginosa dual-species biofilms. Time-series observations revealed that the dominance of P. mirabilis was synchronized with mineral formation in the biofilm. After 24 h of development, the dual-species biofilm was dominated by P. mirabilis, and the distribution of P. mirabilis biomass was strongly correlated with the mineral fraction of the biofilm. Conversely, dual-species growth without biomineralization yielded strikingly different patterns in the biofilm, with P. aeruginosa dominating the biofilm biomass. These results show that biomineralization is responsible for the increased success of P. mirabilis in the polymicrobial biofilm. Since biofilm biomineralization commonly occurs in diverse clinical, natural and engineered systems, these findings imply that biomineralization could broadly influence the microbial ecology of multispecies biofilms. [ABSTRACT FROM AUTHOR]

Published
2016
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108. A multiscale model for integrating hyporheic exchange from ripples to meanders

Author

Stonedahl, Susa H., Harvey, Judson W., Worman, Anders, Salehin, Mashfiqus, Packman, Aaron I., Stonedahl, Susa H., Harvey, Judson W., Worman, Anders, Salehin, Mashfiqus, and Packman, Aaron I.

Abstract

It is necessary to improve our understanding of the exchange of dissolved constituents between surface and subsurface waters in river systems in order to better evaluate the fate of water-borne contaminants and nutrients and their effects on water quality and aquatic ecosystems. Here we present a model that can predict hyporheic exchange at the bed-form-to-reach scale using readily measurable system characteristics. The objective of this effort was to compare subsurface flow induced at scales ranging from very small scale bed forms up to much larger planform geomorphic features such as meanders. In order to compare exchange consistently over this range of scales, we employed a spectral scaling approach as the basis for a generalized analysis of topography-induced stream-subsurface exchange. The spectral model involves a first-order approximation for local flow-boundary interactions but is fully three-dimensional and includes the lateral hyporheic zone in addition to the flow directly beneath the streambed. The primary model input parameters are stream velocity and slope, sediment permeability and porosity, and detailed measurements of the stream channel topography. The primary outputs are the distribution of water flux across the stream channel boundary, the resulting pore water flow paths, and the subsurface residence time distribution. We tested the bed-form-exchange component of the model using a highly detailed two-dimensional data set for exchange with ripples and dunes and then applied the model to a three-dimensional meandering stream in a laboratory flume. Having spatially explicit information allowed us to evaluate the contributions of both gravitational and current-driven hyporheic flow through various classes of stream channel features including ripples, dunes, bars, and meanders. The model simulations indicate that all scales of topography between ripples and meanders have a significant effect on pore water flow fields and residence time distributions. F, QC 20110501

Published
2010
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111. The Hospital Microbiome Project: Meeting report for the 2nd Hospital Microbiome Project, Chicago, USA, January 15th, 2013

Author

Shogan, Benjamin D., primary, Smith, Daniel P., additional, Packman, Aaron I., additional, Kelley, Scott T., additional, Landon, Emily M, additional, Bhangar, Seema, additional, Vora, Gary J., additional, Jones, Rachael M., additional, Keegan, Kevin, additional, Stephens, Brent, additional, Ramos, Tiffanie, additional, Kirkup, Benjamin C., additional, Levin, Hal, additional, Rosenthal, Mariana, additional, Foxman, Betsy, additional, Chang, Eugene B., additional, Siegel, Jeffrey, additional, Cobey, Sarah, additional, An, Gary, additional, Alverdy, John C., additional, Olsiewski, Paula J., additional, Martin, Mark O., additional, Marrs, Rachel, additional, Hernandez, Mark, additional, Christley, Scott, additional, Morowitz, Michael, additional, Weber, Stephen, additional, and Gilbert, Jack, additional

Published
2013
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