Automatic system for long-term monitoring of soil N_2O isotope flux at high temporal and spatial resolution.

摘要

Measuring soil N_2O flux accurately is a major challenge. Most investigations rely on laborious manual measurement campaigns, which despite the large effort required, often do not provide data with high enough spatial and temporal resolution to capture peak flux events. We have developed a novel measurement system that is able to accurately measure isotopes of N_2O in soil trace gas flux with high temporal resolution and from multiple chambers. The system comprises a set of automatic chambers, circulating gas paths and a laser spectroscopy-based N_2O isotopic analyzer. Sampling sequence, deployment time and time between chamber samplings are easy to modify for up to 8 soil chambers. Optional sampling interruption during rain events is customizable at different rain intensities and with different delay options. The system has been deployed to measure soil N_2O emissions during three different campaigns in Columbia County (WI). These campaigns include a full growing season (7 months) and two year-round studies during which the system provided on average 10 daily high-resolution flux measurements for each of four chambers. This measurement system provides precise flux measurements over extended periods, enabling capture of peak events and providing unique insights into microbiological processes governing soil N_2O evolution.