Abstract. Soil CO₂ flux (F_s) is a carbon cycling metric crucial for assessing ecosystem carbon budgets and global warming. However, global F_s datasets often suffer from low temporal-spatial resolution, as well as from spatial bias. F_s observations are severely deficient in tundra and dryland ecosystems due to financial and logistical constraints of current methods for F_s quantification. In this study, we introduce a novel, low-cost sensor system (LC-SS) for long-term, continuous monitoring of soil CO₂ concentration and flux. The LC-SS, built from affordable, open-source hardware and software, offers a cost-effective solution (~USD700), accessible to low-budget users, and opens the scope for research with a large number of sensor system replications. The LC-SS was tested over ~6 months in arid soil conditions, where fluxes are small, and accuracy is critical. CO₂ concentration and soil temperature were measured at 10-min intervals at depths of 5 and 10 cm. The LC-SS demonstrated high stability and minimal maintenance requirements during the tested period. Both diurnal and seasonal soil CO₂ concentration variabilities were observed, highlighting the system's capability of continuous, long-term, in-situ monitoring of soil CO₂ concentration. In addition, F_s was calculated using the measured CO₂ concentration via the gradient method and validated with F_s measured by the flux chamber method using the well-accepted LI-COR gas analyzer system. Gradient method F_s was in good agreement with flux chamber F_s, highlighting the potential for alternative or concurrent use of the LC-SS with current methods for F_s estimation. Leveraging the accuracy and cost-effectiveness of the LC-SS (below 10 % of automated gas analyzer system cost), strategic implementation of LC-SSs could be a promising means to effectively increase the number of measurements, spatially and temporally, ultimately aiding in bridging the gap between global F_s uncertainties and current measurement limitations.

中文翻译：

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克服土壤 CO2 通量长期连续监测的障碍：一种低成本的传感器系统


摘要。土壤 CO₂ 通量 （F_s） 是评估生态系统碳收支和全球变暖的关键碳循环指标。然而，全球 F_s 数据集通常受到低时空分辨率和空间偏差的影响。由于当前 F_s 量化方法的财务和后勤限制，苔原和旱地生态系统的 F_s 观测严重不足。在本研究中，我们介绍了一种新型、低成本的传感器系统 （LC-SS），用于长期、连续监测土壤 CO₂ 浓度和通量。LC-SS 由经济实惠的开源硬件和软件构建而成，提供了一种经济高效的解决方案 （~700 USD），可供低预算用户使用，并通过大量传感器系统复制开辟了研究范围。LC-SS 在通量很小且准确性至关重要的干旱土壤条件下进行了 ~6 个月的测试。在 5 cm 和 10 cm 深度每隔 10 分钟测量一次 CO₂ 浓度和土壤温度。LC-SS 在测试期间表现出高稳定性和最低维护要求。观察到土壤_CO2 浓度的昼夜和季节性变化，突出了该系统对土壤 CO2_浓度进行连续、长期、原位监测的能力。此外，使用通过梯度法测得的 CO₂ 浓度计算 F_s，并使用广受认可的 LI-COR 气体分析仪系统通过通量室法测量的 F_s 进行验证。 梯度方法 F_s 与磁通量室 F_s 非常一致，突出了 LC-SS 与当前 F_s 估计方法替代或同时使用的潜力。利用 LC-SS 的准确性和成本效益（低于自动气体分析仪系统成本的 10%），战略性实施 LC-SS 可能是一种很有前途的手段，可以在空间和时间上有效增加测量次数，最终有助于弥合全球 F_s 不确定性与当前测量限制之间的差距。