The National Ecological Observatory Network Aquatic Sampling: Dissolved Gas Concentrations, Stratification Conditions In Lakes, And Reaeration Rates In Streams
Cawley, Kaelin M 1 ; Goodman, Keli 2
1 National Ecoloogical Observatory Network (NEON)
2 National Ecological Observatory Network (NEON)
The National Ecological Observatory Network (NEON) is deploying instrumentation and collecting samples on a continental spatial scale planned to operate for 30 years starting in 2018. There are five components of NEON: Airborne Observation Platform (AOP), Terrestrial Instrument System (TIS), Terrestrial Observation System (TOS), Aquatic Instrument System (AIS), and Aquatic Observation System (AOS). Collocation of measurements associated with each of these components will allow for linkage and comparison of data related to physical, chemical, and biological parameters. The NEON Aquatic subsystem, comprised of AOS and AIS, will quantify the impacts of climate change, land use, and biological invasions on freshwater populations and processes through standardized sampling, including organismal community composition, surface and groundwater chemistry, and habitat structure, in addition to deploying instrumentation in and around water bodies. The standardization of protocols across all sites is a key to the success of NEON (and its novelty) and will be maintained at all sites through time. Additionally, data processing is standardized, and quality-controlled data products derived from NEON measurements are freely available through the data portal.
As part of the AOS sub-system, samples will be collected bi-weekly from 24 streams and 3 rivers and monthly from 7 lakes for analysis of greenhouse gas (CO2, N2O, and CH4) concentrations. At the same time depth profiles for temperature, conductivity, and dissolved oxygen will be collected in the 7 lake and 3 river sites. From these depth profiles, stratification conditions at the lakes and rivers can be discerned. At stream sites, reaeration tracer experiments (simultaneous conservative and gas tracer injection) will be performed about 8 times per year. The reaeration rates will be related to discharge values to develop a rating curve from which temporally interpolated reaeration rates can be derived from high frequency discharge data. Based off of dissolved gas concentrations and physical parameters, estimates of GHG fluxes can be made and the relationship between fluxes and physical characteristics of inland waters, such as lake mixing and stratification or stream reaeration rates, can be elucidated.