scholarly journals Transformation of organic micropollutants along hyporheic flow in bedforms of river-simulating flumes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anna Jaeger ◽  
Malte Posselt ◽  
Jonas L. Schaper ◽  
Andrea Betterle ◽  
Cyrus Rutere ◽  
...  
Keyword(s):  
Microbial Community ◽  
Hydrodynamic Model ◽  
Reactive Transport ◽  
Water Quality Management ◽  
River Sediments ◽  
Small Scale ◽  
Organic Micropollutants ◽  
Specific Behavior ◽  
Hyporheic Flow ◽  
Scale Heterogeneity

AbstractUrban streams receive increasing loads of organic micropollutants from treated wastewaters. A comprehensive understanding of the in-stream fate of micropollutants is thus of high interest for water quality management. Bedforms induce pumping effects considerably contributing to whole stream hyporheic exchange and are hotspots of biogeochemical turnover processes. However, little is known about the transformation of micropollutants in such structures. In the present study, we set up recirculating flumes to examine the transformation of a set of micropollutants along single flowpaths in two triangular bedforms. We sampled porewater from four locations in the bedforms over 78 days and analysed the resulting concentration curves using the results of a hydrodynamic model in combination with a reactive transport model accounting for advection, dispersion, first-order removal and retardation. The four porewater sampling locations were positioned on individual flowpaths with median solute travel times ranging from 11.5 to 43.3 h as shown in a hydrodynamic model previously. Highest stability was estimated for hydrochlorothiazide on all flowpaths. Lowest detectable half-lives were estimated for sotalol (0.7 h) and sitagliptin (0.2 h) along the shortest flowpath. Also, venlafaxine, acesulfame, bezafibrate, irbesartan, valsartan, ibuprofen and naproxen displayed lower half-lives at shorter flowpaths in the first bedform. However, the behavior of many compounds in the second bedform deviated from expectations, where particularly transformation products, e.g. valsartan acid, showed high concentrations. Flowpath-specific behavior as observed for metformin or flume-specific behavior as observed for metoprolol acid, for instance, was attributed to potential small-scale or flume-scale heterogeneity of microbial community compositions, respectively. The results of the study indicate that the shallow hyporheic flow field and the small-scale heterogeneity of the microbial community are major controlling factors for the transformation of relevant micropollutants in river sediments.

A Multiscale Finite Element Framework for Reactive Contaminant Transport in Heterogeneous Porous Media

2008 ◽  
Author(s):  
K. B. Nakshatrala ◽  
A. J. Valocchi
Keyword(s):  
Reactive Transport ◽  
Chemical Species ◽  
Interfacial Area ◽  
Heterogeneous Porous Media ◽  
Major Influence ◽  
Small Scale ◽  
Full Resolution ◽  
Scale Heterogeneity ◽  
Reactive Pollutant ◽  
Reservoir Description

Mixing of chemical species across plume boundaries has a major influence upon the fate of the reactive pollutant in the subsurface. Small-scale heterogeneity leads to irregular plume boundaries which enhances mixing-controlled reactions through increasing the interfacial area of the plume. Therefore, it is crucial to capture this small-scale heterogeneity in order to properly model reactive transport. Unfortunately, computational limitations do not permit full resolution of the smallest scales of heterogeneity as the size of geomodels used for reservoir description typically exceeds by several orders of magnitude the capabilities of conventional reservoir simulators. Thus, it is necessary to use a coarse numerical grid, particularly for the cases with a large number of reactive species.

Habitat Heterogeneity and Associated Microbial Community Structure in a Small-Scale Floodplain Hyporheic Flow Path

2009 ◽  
Vol 58 (3) ◽  
pp. 611-620 ◽  
Author(s):  
Jennifer L. Lowell ◽  
Nathan Gordon ◽  
Dale Engstrom ◽  
Jack A. Stanford ◽  
William E. Holben ◽  
...  
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Community Structure ◽  
Habitat Heterogeneity ◽  
Flow Path ◽  
Small Scale ◽  
Hyporheic Flow

Small-scale heterogeneity in carbon dioxide, nitrous oxide and methane production from aggregates of a cultivated sandy-loam soil

2008 ◽  
Vol 40 (9) ◽  
pp. 2468-2473 ◽  
Author(s):  
Benjamin K. Sey ◽  
Ameur M. Manceur ◽  
Joann K. Whalen ◽  
Edward G. Gregorich ◽  
Philippe Rochette
Keyword(s):  
Carbon Dioxide ◽  
Nitrous Oxide ◽  
Methane Production ◽  
Sandy Loam ◽  
Sandy Loam Soil ◽  
Small Scale ◽  
Scale Heterogeneity ◽  
Loam Soil

scholarly journals Identification of candidate soil microbes responsible for small-scale heterogeneity in strawberry plant vigour

2016 ◽  
Vol 15 (9) ◽  
pp. 2049-2058 ◽  
Author(s):  
Feng WEI ◽  
Rong FAN ◽  
Thomas Passey ◽  
Xiao-ping HU ◽  
Xiangming Xu
Keyword(s):  
Soil Microbes ◽  
Small Scale ◽  
Strawberry Plant ◽  
Plant Vigour ◽  
Scale Heterogeneity

Metagenomic and Metatranscriptomic Responses of Chemical Dispersant Application during a Marine Dilbit Spill

2022 ◽  
Author(s):  
Yiqi Cao ◽  
Baiyu Zhang ◽  
Charles W. Greer ◽  
Kenneth Lee ◽  
Qinhong Cai ◽  
...  
Keyword(s):  
Microbial Community ◽  
Late Stage ◽  
Large Scale ◽  
Community Dynamics ◽  
Early Stage ◽  
Small Scale ◽  
Rrna Gene ◽  
Shotgun Metagenomics ◽  
Microcosm Studies ◽  
Over Time

The global increase in marine transportation of dilbit (diluted bitumen) can increase the risk of spills, and the application of chemical dispersants remains a common response practice in spill events. To reliably evaluate dispersant effects on dilbit biodegradation over time, we set large-scale (1500 mL) microcosms without nutrients addition using low dilbit concentration (30 ppm). Shotgun metagenomics and metatranscriptomics were deployed to investigate microbial community responses to naturally and chemically dispersed dilbit. We found that the large-scale microcosms could produce more reproducible community trajectories than small-scale (250 mL) ones based on the 16S rRNA gene amplicon sequencing. In the early-stage large-scale microcosms, multiple genera were involved into the biodegradation of dilbit, while dispersant addition enriched primarily Alteromonas and competed for the utilization of dilbit, causing depressed degradation of aromatics. The metatranscriptomic based Metagenome Assembled Genomes (MAG) further elucidated early-stage microbial antioxidation mechanism, which showed dispersant addition triggered the increased expression of the antioxidation process genes of Alteromonas species. Differently, in the late stage, the microbial communities showed high diversity and richness and similar compositions and metabolic functions regardless of dispersant addition, indicating the biotransformation of remaining compounds can occur within the post-oil communities. These findings can guide future microcosm studies and the application of chemical dispersants for responding to a marine dilbit spill. Importance In this study, we employed microcosms to study the effects of marine dilbit spill and dispersant application on microbial community dynamics over time. We evaluated the impacts of microcosm scale and found that increasing the scale is beneficial for reducing community stochasticity, especially in the late stage of biodegradation. We observed that dispersant application suppressed aromatics biodegradation in the early stage (6 days) whereas exerting insignificant effects in the late stage (50 days), from both substances removal and metagenomic/metatranscriptomic perspectives. We further found that Alteromonas species are vital for the early-stage chemically dispersed oil biodegradation, and clarified their degradation and antioxidation mechanisms. The findings would help to better understand microcosm studies and microbial roles for biodegrading dilbit and chemically dispersed dilbit, and suggest that dispersant evaluation in large-scale systems and even through field trails would be more realistic after marine oil spill response.

Quantifying microplastic particle transport and retention in an experimental flume environment

2021 ◽  
Author(s):  
Jan-Pascal Boos ◽  
Benjamin Gilfedder ◽  
Sven Frei
Keyword(s):  
Particle Transport ◽  
Solid Phase ◽  
River Sediments ◽  
Time Resolved ◽  
Fluvial Systems ◽  
Particle Mobility ◽  
Hyporheic Flow ◽  
Scale Experiment ◽  
Streambed Sediments ◽  
Experimental Flume

<p>Rivers and streams are the dominant transport vectors for microplastic (MP) input into marine environments. During transport, complex physicochemical interactions between particles, water and river sediments influence particle mobility and retention. The specific transport mechanisms of MP in fluvial systems are not yet fully understood, and the main reason lies in the limitation in reliable data derived from experimental analysis.</p><p>In our subproject of the ‘CRC 1357 Microplastics’, we investigate the hydrodynamic mechanisms that control the transport and retention behavior of MP in open channel flows and streambed sediments. In an experimental flume environment, we create realistic hydrodynamic and hyporheic flow conditions by using various porous media (e.g. glass beads or sand) and bedform structures (e.g. riffle-pool sequences, ripples and dunes), modelled from real stream systems.</p><p>The method developed here can quantitatively analyze the transport of pore-scale particles (1-40 µm) based on fluorometric techniques. Particle velocity distributions and particle transport are measured using Particle-Image-Velocimetry and Laser-Doppler-Velocimetry. With our setup, we can quantitatively investigate time-resolved MP transport and retention through the aqueous and solid phase in a flume scale experiment.</p>

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