Specifications_2.pdf

Technical Specification: Automated Soil CO2 Flux system with multiple chambers

Description:

The U.S. Geological Survey, Southwest Biological Science Center, Canyonlands Research Station (CRS), is conducting a series of biological soil crust-CO2 efflux-soil water relation studies that we hope to combine in analyses to evaluate regional trends and climate-plant-soil interactions. To conduct this research we require an automated Soil CO2 Flux system with multiple chambers to take unattended, long-term sequential CO2 and CH4 measurements at up to 8 locations. The system should have the capacity to investigate soil moisture, soil temperature, precipitation events, and photosynthetically active radiation that affect soil CO2 rates. In addition, 8 clear long-term chambers that run with the system, extension cables and an adapter kit that allows us to do trace gases in addition to carbon dioxide are needed. This powerful tool will allow CRS to collect a highly resolved timeline of data that would be impossible without this equipment.

Specifications:

Weatherproof multiplexer with operating temperature range of -20 °C to 45 °C, a relative humidity range of 0% to 95%, barometric pressure sensor range of 20 kPa to 110 kPa, pressure sensor accuracy of ±0.4 kPa from 50 to 110 kPa, a flow rate of ~2.0 lpm. Space of 8 GB user data storage.

Trace Gas Analyzer that measures CO2 or H2O at a rate of one sample per second using Optical Feedback Cavity Enhanced Absorption Spectroscopy. For CO2 the measurement range should be 1 ppm to 10,000 ppm with a precision of 0.01 - 0.04 ppm at 400 ppm with 1 – 5 second averaging. For H2O the measurement range should be 0 ppm to 60,000 ppm with a precision of 20 - 45 ppm at 10,000 ppm with 1 – 5 second averaging. The analyzer should operate under normal operating conditions at a temperature range of -20 °C to 45 °C, a humidity range of 0% to 85%, and a pressure range of 70 kPa to 110 kPa

Weatherproof clear chamber with a minimum volume of 3900 cm3 covering a minimum soil area of 300 cm2. Chamber should allow organisms inside to continue to receive light throughout the measurement. Associated air temperature thermistor should have an operating range of -20 to 50 °C with an accuracy of ±0.3 °C and light sensor with a range of 0 to 100 µA. Minimum cable length of 15 m.