Open AccessDissolved oxygen sensor in an automated hyporheic sampling system reveals biogeochemical dynamics
Author(s) -
Matt Kaufman,
Ruby N. Ghosh,
Jay W. Grate,
D. Shooltz,
Michael Freeman,
Terry M. Ball,
R. Loloee,
Charles W. McIntire,
Jacqueline Wells,
Chris Strickland,
Vince R. Vermeul,
Kenton A. Rod,
Rob D. Mackley,
Xinming Lin,
Huiying Ren,
Amy Goldman,
James Stegen
Publication year - 2022
Publication title -
plos water
Language(s) - English
Resource type - Journals
ISSN - 2767-3219
DOI - 10.1371/journal.pwat.0000014
Subject(s) - biogeochemical cycle , biogeochemistry , hyporheic zone , hydrology (agriculture) , environmental science , sampling (signal processing) , streams , hydraulic head , tracer , geology , surface water , ecology , oceanography , environmental engineering , engineering , computer network , geotechnical engineering , physics , nuclear physics , filter (signal processing) , computer science , electrical engineering , biology
Many river corridor systems frequently experience rapid variations in river stage height, hydraulic head gradients, and residence times. The integrated hydrology and biogeochemistry of such systems is challenging to study, particularly in their associated hyporheic zones. Here we present an automated system to facilitate 4-dimensional study of dynamic hyporheic zones. It is based on combining real-time in-situ and ex-situ measurements from sensor/sampling locations distributed in 3-dimensions. A novel dissolved oxygen (DO) sensor was integrated into the system during a small scale study. We measured several biogeochemical and hydrologic parameters at three subsurface depths in the riverbed of the Columbia River in Washington State, USA, a dynamic hydropeaked river corridor system. During the study, episodes of significant DO variations (~+/- 4 mg/l) were observed, with minor variation in other parameters (e.g., <~+/-0.15 mg/l NO 3 ). DO concentrations were related to hydraulic head gradients, showing both hysteretic and non-hysteretic relationships with abrupt (hours) transitions between the two types of relationships. The observed relationships provide a number of hypotheses related to the integrated hydrology and biogeochemistry of dynamic hyporheic zones. We suggest that preliminary high-frequency monitoring is advantageous in guiding the design of long term monitoring campaigns. The study also demonstrated the importance of measuring multiple parameters in parallel, where the DO sensor provided the key signal for identifying/detecting transient phenomena.