Cook, Sarah, Price, Oliver, King, Andrew, Finnegan, Chris, van Egmond, Roger, Schäfer, Hendrik, Pearson, Jonathan M., Abolfathi, Soroush and Bending, G. D. (2020) Bedform characteristics and biofilm community development interact to modify hyporheic exchange. Science of The Total Environment . doi:10.1016/j.scitotenv.2020.141397 (In Press)

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Abstract

The physical and biological attributes of riverine ecosystems interact in a complex manner which can affect the hydrodynamic behaviour of the system. This can alter the mixing characteristics of a river at the sediment-water interface. Research on hyporheic exchange has increased in recent years driven by a greater appreciation for the importance of this dynamic ecotone in connecting and regulating river systems. An understanding of process-based interactions driving hyporheic exchange is still limited, specifically the feedbacks between the physical and biological controlling factors. The interplay between bed morphology and sediment size on biofilm community development and the impact on hyporheic exchange mechanisms, was experimentally considered. Purpose built recirculating flume systems were constructed and three profiles of bedform investigated: i) flat, ii) undulating λ = 1 m ii) undulating λ = 0.2 m, across two different sized sediments (0.5 mm and 5 mm). The influence of biofilm growth and bedform interaction on hyporheic exchange was explored, over time, using discrete repeat injections of fluorescent dye into the flumes. Hyporheic exchange rates were greatest in systems with larger sediment sizes (5 mm) and with more bedforms (undulating λ = 0.2). Sediment size was a dominant control in governing biofilm growth and hyporheic exchange in systems with limited bedform. In systems where bedform was prevalent, sediment size and biofilm appeared to no longer be a control on exchange due to the physical influence of advective pumping. Here, exchange rates within these environments were more consistent overtime, despite greater microbial growth. As such, bedform has the potential to overcome the rate limiting effects of biotic factors on hyporheic exchange and sediment size on microbial penetration. This has implications for pollutant and nutrient penetration; bedforms increase hydrological connectivity, generating the opportunity to support microbial communities at depth and as such, improve the self-purification ability of river systems.

Item Type:	Journal Article
Subjects:	Q Science > QH Natural history Q Science > QR Microbiology T Technology > TA Engineering (General). Civil engineering (General) T Technology > TC Hydraulic engineering. Ocean engineering T Technology > TD Environmental technology. Sanitary engineering
Divisions:	Faculty of Science > Life Sciences (2010- ) > Biological Sciences ( -2010) Faculty of Science > Engineering Faculty of Science > Life Sciences (2010- )
Library of Congress Subject Headings (LCSH):	Hyporheic zones , Stream ecology , Biofilms, Sedimentation and deposition
Journal or Publication Title:	Science of The Total Environment
Publisher:	Elsevier Science BV
ISSN:	0048-9697
Official Date:	7 August 2020
Dates:	Date Event 7 August 2020 Available 29 July 2020 Accepted
Date of first compliant deposit:	13 August 2020
DOI:	10.1016/j.scitotenv.2020.141397
Status:	Peer Reviewed
Publication Status:	In Press
Access rights to Published version:	Restricted or Subscription Access
Grant number:	(Grants and and
RIOXX Funder/Project Grant:	Project/Grant ID RIOXX Funder Name Funder ID NE/H018980/1 [NERC] Natural Environment Research Council http://dx.doi.org/10.13039/501100000270 NE/R003645/1 [NERC] Natural Environment Research Council http://dx.doi.org/10.13039/501100000270 UNSPECIFIED Unilever http://dx.doi.org/10.13039/100007190

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