Practical guidelines for reproducible N 2 O flux chamber measurements in nutrient-poor ecosystems

<p>The atmospheric concentration of nitrous oxide (<span class="inline-formula">N₂O</span>) has increased significantly since 1800, mainly due to agricultural activities. However, due to their large area, nutrient-poor natural soils, including those in the (sub-) Arctic, also play a crucial role in <span class="inline-formula">N₂O</span> emissions and consumption. Despite their importance, these soils have been understudied, due to methodological limitations in detecting low fluxes. Our study addresses this knowledge gap by testing a fast-responding portable gas analyser (PGA; Aeris MIRA Ultra <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow class="chem"><msub><mi mathvariant="normal">N</mi><mn mathvariant="normal">2</mn></msub><mi mathvariant="normal">O</mi><mo>/</mo><msub><mi mathvariant="normal">CO</mi><mn mathvariant="normal">2</mn></msub></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="50pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="1198afae3fddbeac3f158918b70874bb"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-18-3407-2025-ie00001.svg" width="50pt" height="14pt" src="amt-18-3407-2025-ie00001.png"/></svg:svg></span></span>) combined with manual chambers (height and diameter: 25 <span class="inline-formula">cm</span>) for measuring <span class="inline-formula">N₂O</span> fluxes from a nutrient-poor, sub-Arctic peatland. Our results show that this setup can detect and quantify low <span class="inline-formula">N₂O</span> flux rates, with a mean and standard error of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">0.61</mn><mo>±</mo><mn mathvariant="normal">0.08</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="64pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="0f4baef41c35e0eea360c1f54aff0e6d"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-18-3407-2025-ie00002.svg" width="64pt" height="10pt" src="amt-18-3407-2025-ie00002.png"/></svg:svg></span></span> <span class="inline-formula">µg</span> <span class="inline-formula">N₂O</span>-<span class="inline-formula">N</span> <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M13" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><msup><mi mathvariant="normal">m</mi><mrow><mo>-</mo><mn mathvariant="normal">2</mn></mrow></msup><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">h</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="39pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="7d5f1ff3744b20a3bbdaae9d67d679c1"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-18-3407-2025-ie00003.svg" width="39pt" height="13pt" src="amt-18-3407-2025-ie00003.png"/></svg:svg></span></span> for a 5 <span class="inline-formula">min</span> closure time, as observed in our study. More than 70 <span class="inline-formula">%</span> of the measured <span class="inline-formula">N₂O</span> fluxes exceeded the minimum detectable flux (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M17" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">0.027</mn><mo>±</mo><mn mathvariant="normal">0.0002</mn><mspace width="0.125em" linebreak="nobreak"/><mrow class="unit"><mi mathvariant="normal">µ</mi><mi mathvariant="normal">mol</mi><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">m</mi><mrow><mo>-</mo><mn mathvariant="normal">2</mn></mrow></msup><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">h</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="138pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="cf70b445337f7eb6552e485c9b4d1631"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-18-3407-2025-ie00004.svg" width="138pt" height="15pt" src="amt-18-3407-2025-ie00004.png"/></svg:svg></span></span>), which varied according to chamber closure time. Our study highlights the importance of using fast-responding analysers to measure low <span class="inline-formula">N₂O</span> fluxes and improve our understanding of diverse <span class="inline-formula">N₂O</span> flux dynamics. For nutrient-poor soils, we recommend a chamber closure time of approximately 5 <span class="inline-formula">min</span>. We also found that a non-linear flux calculation model yielded better results and was broadly applicable, including cases where data were linearly distributed. Overall, our study demonstrates the potential of fast-responding analysers to improve our understanding of <span class="inline-formula">N₂O</span> flux dynamics in nutrient-poor soils.</p>

Abstract licence: CC BY

A person counts once a day per paper. We keep no cookie and no address: a reader is a hash that changes every day. Any month under five reads shows no number.