HS1.2.1

Environmental monitoring programs carried out by expeditions or autonomous stations are expensive and only allow measurements for discrete times and locations. After data acquisition most of the data needs hand-operated validation and evaluation before being stored in databases.

For a higher local and temporal resolution on parameters of marine ecosystems, it is planned to extend monitoring programs by attaching a small-sized module, which combines a microcontroller with multiple sensors, to ships of opportunity or any other suitable platform. The modules design focuses on the usability, reliability and interoperability of the derived data by using metadata information and assessing in-situ which data is relevant to be measured and stored.

Using an ESP32, a popular microcontroller, to collect data from OEM sensors of different manufacturers enables a high flexibility in parameters and sensor types. The use of different OEM sensors also allows to experiment with unconventional hydrological sensors. The proposed open source module attempts to collect data as reliable as with conventional monitoring sensor systems.

This approach allows an event based data acquisition, e.g. by adjusting the sampling rate so that only as much data as necessary is measured. In order to provide precise spatio-temporal referencing, the system contains a real time clock and GPS positioning. Moreover, storing the raw data of the sensors alongside their calibration coefficients enables post-processing of the data. The ESP32 transmits the stored data to a server via WiFi or an external LTE module. From this point on, a machine-based validation, flagging of relevant data and basic visualization can assist the evaluation.

With such a module integrating multiple sensors and focusing on the interpretation and use of data starting at the measurement, reliable and pre-evaluated data from hard to access areas can be obtained and contribute to the assessment of dynamic and heterogeneous ecosystems.

How to cite: Björner, M., Naumann, M., Furkert, F., Stepputtis, D., Hermann, A., Gag, M., Eilek, S., and Wagner, R.: Using an open source approach to remotely collect reliable environmental data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2722, https://doi.org/10.5194/egusphere-egu22-2722, 2022.

Measurements of greenhouse gas (GHG) emissions such as carbon dioxide (CO_­­2) play an important role in finding solutions to mitigate the global climate crises. In case of direct treatment comparisons, dynamic manual closed chamber systems are often used to measure the CO₂ exchange and determine the treatment corresponding net ecosystem C balance (NECB). These measurements are commonly accompanied by records of non-destructive spectral vegetation indices such as RVI and NDVI, which can be used to validate obtained CO₂ flux dynamics, to improve the accuracy and precision of determined CO₂ exchange during gap-filling, and for up-scaling purposes. However, commercially available systems for both measurements of CO₂ exchange and spectral vegetation indices are usually cost-intensive, which resulted in a long-term focus in GHG research on the northern hemisphere and the fact that studies on agroecosystems in sub-Saharan Africa as well as Southeast Asia are still being underrepresented.

We present two portable, inexpensive, open source devices to measure in situ 1) CO₂ fluxes using the manual closed chamber method; and 2) vegetation spectral indices, such as NDVI and RVI. The CO₂ flux measurement device consists of a combination of multiple low-cost sensors, such as a NDIR-based CO­₂ sensor (K30FR; 0-10,000 ppm, ± 30 ppm accuracy), a DHT-22 (humidity and temperature) and a BMP280 (air pressure). Sensors are connected to a bluetooth enabled, battery powered, compact microcontroller based logger unit for data visualization and storage.  The handheld, NDVI measurement device consist of a combination of two faced up and two faced down visible (AS7262) and IR (AS7263) sensors, as well as a CCS811 and BME280 for parallel measurements of relevant environmental parameters (e.g., ambient temperature and relative humidity). Sensor control, data visualization and storage is implemented using again a bluetooth enabled, battery powered, compact microcontroller based logger unit. Here, we present the design, and first results of both low-cost devices. Results were validated against results of customized CO₂ and NDVI measurement systems using regular scientific sensors (LI-COR 850 and SKR 1840(ND) and data logger components (CR1000). 

Keywords: CO₂ exchange measurements, closed chamber, NDVI, low-cost open source DIY device

How to cite: Macagga, R., Antonijevic, D., Monzon, R., Bayot, R., Lueck, M., Asante, M., Sossa, L. G., Sanchez, P., Augustin, J., and Hoffmann, M.: Portable low cost devices for in situ measurements of CO2 exchange and vegetation spectral indices: Design and first results., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3517, https://doi.org/10.5194/egusphere-egu22-3517, 2022.

Analyses of the relationships between climate, air substances and health usually concentrate on urban environments due to increased urban temperatures, high levels of air pollution and the exposure of a large number of people compared to rural environments. Ongoing urbanization, demographic aging and climate change lead to an increased vulnerability with respect to climate-related extremes and air pollution. However, systematic analyses of the specific local-scale characteristics of health-relevant atmospheric conditions and compositions in urban environments are still scarce due to the lack of high-resolution monitoring networks. In recent years low-cost sensors became available, which potentially provide the opportunity to monitor atmospheric conditions with a high spatial resolution and which allow monitoring directly at exposed people.

We develop a measurement system for several air substances like ozone, nitrogen oxides, carbon monoxide and particulate matter as well as meteorological variables like temperature and relative humidity, based on low-cost sensors. This involves the assembly of compact, weatherproof boxes with 3D-printed parts. They contain a control unit based on Arduino hardware to gather the sensor data as well as self-designed printed circuit boards (PCBs). A Pycom microcontroller is used for low-power, high-temporal data transmissions by Long-Term Evolution Cat-M1 (LTE-M). These Atmospheric Exposure Low-cost Monitoring units (AELCM) include digital and analogue sensors for air substances and meteorological variables, LCD display, RTC module, uninterruptible power supply, active ventilation, a SD Module as a data black box in addition to an optional internally running FTP server and optional GPS module. A computational fluid dynamics (CFD) simulation is used to evaluate the air flow inside the AELCM units. Sensors are selected based on own analyses as well as according to evaluation and performance in other projects. The measurement equipment is extensively tested using the high-quality measurement unit for meteorology and air substances (Atmospheric Exposure Monitoring System, AEMS) of our research group, located at the Augsburg University Hospital.

How to cite: Gäbel, P., Koller, C., and Hertig, E.: Development of air quality boxes based on low-cost sensor technology, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3719, https://doi.org/10.5194/egusphere-egu22-3719, 2022.

How to cite: Diederen, D.: Global surface and groundwater levels - hand measurements with a mobile app., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5446, https://doi.org/10.5194/egusphere-egu22-5446, 2022.

Stable water isotopes (δ¹⁸O, δ²H) are used as tracers in hydrology to study the components of the terrestrial water cycle. The stable water isotopes of precipitation are affected by the passage of rainfall through tree canopy, resulting in a change of the tracer signal. Several processes within the canopy are thought to be responsible for this, including evaporation, liquid-vapor equilibration, redistribution, and legacy effects. However, it is currently not clear which processes dominate under which conditions, and predictions of these changes are not yet possible. This is partly due to a lack of high resolution throughfall data, as previous studies usually sampled throughfall in evaporation-reducing bulk containers placed under canopy. Here we propose to hang commonly available cotton products in tree canopy, let them soak up rainfall water, and subsequently measure the stable water isotopes directly from the wet cotton products using the direct liquid-vapor equilibration method in the laboratory. First, four products (two types of tampons, two types of cotton pads) were evaluated in terms of the minimum amount of water drops necessary for a reliable measurement, their price, and ease of handling. Cotton pads had the overall best rating and were therefor hung in a coniferous tree placed in a rainfall simulator. With a fixed rainfall intensity, we tested how long the cotton pads can be left hanging before significant isotopic changes due to evaporation occurred. While cotton pads that were on the outer edge of the canopy showed significant deviations after only half an hour, cotton pads inside the canopy as well as close to the stem could be left hanging for one hour. As a comparison, throughfall was also collected using a bulk sampler under the canopy, and this sample showed no significant changes even after four hours. It can thus be assumed that due to the comparatively low amount of water in the cotton pads (even if soaking wet), evaporative changes of isotope values had a stronger impact on the remaining water compared to the bulk throughfall sampler. This study presents first laboratory results and further tests, in the laboratory or in the field, are called for.

How to cite: Stockinger, M., Ziesel, G., and Stumpp, C.: Using cotton pads to sample the stable water isotopes of throughfall inside tree canopies, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3888, https://doi.org/10.5194/egusphere-egu22-3888, 2022.

Efficient water use is a must for sustainable agriculture, driving the need for affordable soil moisture sensors to guide irrigation timing. Sensors are limited by cost, maintenance and the need for wires for data capture and charging.  We are developing low-cost, long-life, wireless in-situ soil sensing networks, which can potentially enable a much higher sensor density for large farmland or intense research plot monitoring. This custom soil sensor is made from off-the-shelf electronics and consumes approximately 10x less energy per measurement, compared to commercially available sensors. Here we present our new sensor technology, while also investigating its repeatability and accuracy in controlled conditions and comparing it to that of commercially available soil moisture sensors. The final application of the custom soil moisture sensor is an underground in-situ sensing network, which will be enabled through wireless powering and telemetry systems implemented on autonomous vehicles, both ground and aerial.

How to cite: Marin, M., Elsakloul, F., Sanchez, J., Arteaga Saenz, J. M., Boyle, D., O’Keeffe, J. H., Goel, R., Hallett, P. D., Mitcheson, P. D., Norton, G. J., Yeatman, E., Young, D. J., Zesiger, C., and Roundy, S.: Low energy and cost soil moisture sensor technology, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5620, https://doi.org/10.5194/egusphere-egu22-5620, 2022.

Plant physiologists have used microscopy to study how leaf anatomy is related to photosynthetic performance and how this relation is affected by environmental conditions. However, leaf anatomy is not invariant over time: small pores on the leaf surface (stomata) open and close within minutes in response to the availability of water, CO₂ and light. Within tens of minutes following a water deficit, cells in many leaves also shrink significantly in volume and the leaf undergoes structural changes as a result of wilting. Gas-exchange setups can monitor changes in photosynthesis and transpiration under such conditions, but classical microscopy techniques are not well-suited to capture the concomitant changes in leaf anatomy for two main reasons. First, available non-destructive microscopy techniques are limited in resolution and imaging depth, making it difficult to analyze changes in anatomy to the required detail. Second, using sectioned fixated samples is known to be associated with tissue shrinkage, swelling or deformation, making estimates of cellular volumes and surfaces prone to artifacts. Moreover, the destructive nature of these techniques makes it impossible to monitor changes in leaf anatomy during ongoing gas-exchange measurements. These limitations hinder advancing our understanding of the relation between leaf anatomy and photosynthesis or transpiration.

Here, we present a novel gas-exchange setup that combines synchrotron-based high-resolution computed tomography (microCT) with concurrent measurements of gas-exchange using an commercially available infra-red gas analyzer. We designed and constructed a novel gas-exchange cuvette with CO₂ and H₂O control that allows for non-invasive monitoring of leaf anatomy in a microCT setup. Custom-built sensors were used to measure light intensity and leaf temperature. At given time points during gas-exchange measurements, 300-500 X-ray projections (100 ms) were taken while the chamber rotated 180°. From this data, a leaf volume corresponding to 0.5 mm² leaf surface was reconstructed at high resolution (0.325 µm per voxel edge).

The setup provides 3D images that can be used to measure the aperture of multiple stomata and the volumes, shapes and surface areas of cells and airspaces within the leaf. We found that the same leaf section can be scanned several times without measurable radiation damage, allowing for the combination of three spatial dimensions with time to create a 4D analysis of the leaf structure. Using poplar, willow and Arabidopsis leaves we studied how leaf anatomy rapidly adjusts after limiting water availability and show that such effects are not limited to the stomatal pore alone. We discuss the issues and pitfalls with the methodology and suggest avenues for future improvement.

How to cite: Tholen, D., Scheffknecht, S., Voggeneder, K., Weiss, E., and Théroux-Rancourt, G.: Leaf Structure and Function in Four Dimensions: Non-invasive MicroCT Imaging During Gas-exchange Measurements, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9801, https://doi.org/10.5194/egusphere-egu22-9801, 2022.

An unknown source of methane (CH₄) was recently discovered under the Kangerlussuaq sector of the Greenland Ice Sheet (GrIS). CH₄ is transported dissolved in meltwater from the subglacial environment to the margin of the ice sheet, where it rapidly degasses to the atmosphere. Existing knowledge gaps concern the magnitude of emissions, seasonal patterns and spatial variations along the margin of the GrIS, which require long-term monitoring and large-scale measurement campaigns at multiple meltwater outlets. A limiting factor for such studies in remote areas is that CH₄ analysers (laser spectroscopy) are power-hungry, maintenance-intensive, and expensive. To overcome these obstacles, we are developing a low-cost, low power sensor for measuring dissolved CH₄ in subglacial meltwater systems in the MetICE project: the WaterWorm.

The WaterWorm is based on a metal oxide sensor (MOS) designed for CH₄ detection (Figaro TGS2611-E00), which is highly sensitive to variations in relative humidity (RH) and temperature. In the WaterWorm, the MOS is encased in a hydrophobic but gas-permeable silicone tube, ensuring a stable and fully saturated headspace (100% RH) during submergence. We calibrated the analogue output (in mV) of the submerged WaterWorm against a reference CH₄ analyser (μGGA, GLA-331, LGR Research) connected to a dissolved gas extraction system (DGES, LGR Research) in temperature-controlled laboratory experiments by stepwise enrichment of the water with CH4. These calibration tests showed that the sensor output (set at two readings per minute) is proportional to dissolved CH₄ at constant humidity and temperature.

During fieldwork near Kangerlussuaq, Greenland, in summer 2021, a field baseline calibration was performed in a meltwater stream on the surface of the GrIS at ambient CH₄ concentrations. WaterWorms were deployed for ten weeks in the meltwater of a small outlet of the Isunnguata Sermia glacier with known CH₄ export and stable meltwater temperatures (0.0 - 0.1°C) to test the sensor under field conditions. Throughout this period, the WaterWorms measured elevated dissolved CH₄ concentrations with diurnal variations that corresponded to similar diurnal variation in gaseous CH₄ measurements performed with the reference CH₄ analyser.

The WaterWorm is a promising and cost-efficient option for the seasonal monitoring of dissolved CH₄ in glacial meltwater. With material costs of only 150€, the WaterWorm can be left unattended in the field and positioned directly at the ice edge. This makes the sensor suitable for a large-scale CH₄ monitoring network along the margin of the GrIS. The next steps involve material tests to build WaterWorms for applications in other aquatic environments and at different water depths.

How to cite: Sapper, S. E., Christiansen, J. R., and Jørgensen, C. J.: The WaterWorm: a low-cost, low power sensor for the detection of dissolved CH4 in glacial meltwater, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9972, https://doi.org/10.5194/egusphere-egu22-9972, 2022.

How to cite: Vergara Niedermayr, B., Antonijevic, D., Monzón, O., and Hoffmann, M.: A novel, low-cost floating chamber design for semi-automatic measurements of CO2 and CH4 emissions from ponds and ditches, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10102, https://doi.org/10.5194/egusphere-egu22-10102, 2022.