DEVELOPMENT AND TESTING OF A SENSOR ROD FOR CHEMICAL AND PHYSICAL MEASUREMENTS IN A TAI

The mission of the Biological and Environmental Research (BER) program is to support transformative science and scientific user facilities to achieve a predictive understanding of complex biological, earth, and environmental systems for energy and infrastructure security and resilience. Earth and Environmental Systems Sciences Division (EESSD) of the office of BER includes among its activities the promotion of fundamental science that enables major scientific developments and modelling of system-relevant earth ecosystems. Developing seasonal to multi-decadal predictive models of earth systems requires long-term field experiments drawing data from a range of sensors and environmental conditions. Some of the largest gaps in existing predictive capability occur at environmental interfaces such as terrestrial-aquatic interfaces (TAIs) in coastal systems. TAIs are subject to highly dynamic conditions and sharp physical, chemical, and biological gradients at a range of scales in both time and space. As such, it is frequently unclear how insight gained at the pore or core scale can be applied to landscape scales covering entire coastlines. One major contributor to this knowledge gap is a lack of data that crosses these scales. Concurrent measurements of a variety of physical, chemical, and biological data will help modelers to unravel the complex inter-dependence of factors that lead to predictive understanding of coastal systems. In order to address this need, this project will develop a sensor system that operates across a range of scales. The system will accomplish this through a network of sensor arrays. Each array consists of a series of individual hydrobiogeochemical sensors embedded in a sensor rod which will be partially driven into the sediment at coastal TAIs. Each node on the array will provide real-time in-situ measurements and together produce a time-resolved vertical profile of parameters from the sediment to the periodically-inundated open water region above the sediment. Low-power telemetry and light-weight communication protocols combined with a low-cost design will allow deployment of a network of rods across multiple microenvironments of a coastline thus bridging the gap from pore to landscape scale. Measurements will have to overcome a number of challenges including steep environmental gradients, highly dynamic conditions, and the challenging physical nature of coastal settings. Multi-cyclical (e.g. daily, seasonal and interannual) patterns are expected. In addition to these cyclical responses, spatially and temporally transient hot spots and hot moments will also be encountered. Capturing these transient events is of particular scientific interest and represents an important challenge for predictive modeling. During the first phase, the unique challenges associated with deploying chemical and physical sensors in a TAI will be evaluated by developing, packaging and deploying rods at a few test locations for several weeks. Data will be telemetrically transmitted to a centralized data server. In the second phase, additional sensors will be added and specific challenges identified in the first phase with regard to reliable autonomous operation will be resolved. Additional coastal field sites will be instrumented, extending from the ocean through tidal estuaries to fresh water marshes and inland riverine locations. The data system will be expanded to accommodate multi-site data as well as data drawn from available sources (meteorological, remote sensing, USGS river data, etc.) to provide a context-rich picture of the monitored regions. Sensors developed in this project will also have commercial application in other fields of study, expanding the commercial viability of the product beyond its primary scientific purpose.