Monitoring Atmospheric, Soil, and Dissolved CO2 Using a Low-Cost, Arduino Monitoring Platform (CO2-LAMP): Theory, Fabrication, and Operation

Abstract

Variability of CO 2 concentrations within the Earth system occurs over a wide range of time and spatial scales. Resolving this variability and its drivers in terrestrial and aquatic environments ultimately requires high-resolution spatial and temporal monitoring; however, relatively high-cost gas analyzers and data loggers can present barriers in terms of cost and functionality. To overcome these barriers, we developed a low-cost Arduino monitoring platform (CO2-LAMP) for recording CO 2 variability in electronically harsh conditions: humid air, soil, and aquatic environments. A relatively inexpensive CO 2 gas analyzer was waterproofed using a semi-permeable, expanded polytetrafluoroethylene membrane. Using first principles, we derived a formulation of the theoretical operation and measurement of PCO 2(aq) by infrared gas analyzers submerged in aquatic environments. This analysis revealed that an IRGA should be able to measure PCO 2(aq) independent of corrections for hydrostatic pressure. CO2-LAMP theoretical operation and measurement were also verified by accompanying laboratory assessment measuring PCO 2(aq) at multiple water depths. The monitoring platform was also deployed at two sites within the Springfield Plateau province in northwest Arkansas, USA: Blowing Springs Cave and the Savoy Experimental Watershed. At Blowing Springs Cave, the CO2-LAMP operated alongside a relatively greater-cost CO 2 monitoring platform. Over the monitoring period, measured values between the two systems covaried linearly (r 2 = 0.97 and 0.99 for cave air and cave stream dissolved CO 2 , respectively). At the Savoy Experimental Watershed, measured soil CO 2 variability capturing sub-daily variation was consistent with previously documented studies in humid, temperate soils. Daily median values varied linearly with soil moisture content (r 2 = 0.84). Overall, the CO2-LAMP captured sub-daily variability of CO 2 in humid air, soil, and aquatic environments that, while out of the scope of the study, highlight both cyclical and complex CO 2 behavior. At present, long-term assessment of platform design is ongoing. Considering cost-savings, CO2-LAMP presents a working base design for continuous, accurate, low-power, and low-cost CO 2 monitoring for remote locations.

Adapting Internet of Things to Arduino-based Devices for Low-Cost Remote Sensing in School Science Learning Environments

“…Various source codes are also shared on GitHub. There have been numerous academic studies conducted using low-cost sensors, focusing on temperature [12], humidity, carbon dioxide [13]- [17], methane [18], fine dust [19]- [28], soil moisture [29], [15], pH [30] and so on.…”

Low cost CO2 sensing: A simple microcontroller approach with calibration and field use

“…Single or dual band NDIR sensors are able to respond to concentration changes of a single gas while alternative sensors may use the change in the electrical resistance of a membrane to monitor concentrations of multiple gases, although using this method to monitor solely CO 2 is likely to create noisy data due to the confounding effect of other gases such as carbon monoxide or methane. There has been some development of low-cost CO 2 data loggers by other teams using microcontrollers and NDIR sensors [2] , [5] , [7] , [3] that demonstrate their accuracy and usefulness. These articles used temporary breadboard connections to connect components and while breadboards have the advantage of allowing multiple different designs to be created and parts easily reused, they are more prone to being physically dislodged or incorrectly setup by novice users.…”

A differential CO2 profile probe approach for field measurements of soil gas transport and soil respiration#

“…Several research groups (Jassal et al., 2005; Hirano, 2003; Tang et al., 2003) used compact non‐dispersive infrared (NDIR) CO 2 sensors to install them directly in the soil after this technology became available. The availability of low‐cost microcontrollers and NDIR sensors stimulates further applications in soil gas research (Blackstock et al., 2019; Heger et al., 2020).…”