Ilona Riipinen, Sini Talvinen, Anouck Chassaing
et al.
In honour of the memory of Prof. Astrid Kiendler-Scharr and her contributions to atmospheric science Uncertainty in estimations of the net contribution of anthropogenic aerosol particles, particularly of aerosol-cloud interactions (ACIs) to the Earth’s radiation budget, limits our ability to understand past and project future climate change. Earth System Models (ESMs) are among the key tools for assessing the magnitude and impacts of changes in various forcing agents on the global climate system. Hence, improving aerosol and cloud descriptions in ESMs is an important way forward to increase the confidence in estimates of climate impacts of aerosol perturbations in the past, present and future. In the framework of the FORCeS project, experimental and theoretical approaches were combined to bridge the current key gaps in the fundamental understanding of essential aerosol and cloud processes and their descriptions in selected European ESMs. Regarding aerosol types and processes, we focused on organic aerosol, particulate nitrate, absorbing aerosols, and ultrafine aerosol sources including new particle formation and growth. In terms of cloud processes, we targeted cloud droplet activation, hydrometeor growth and evaporation, ice formation and multiplication as well as aerosol processing and scavenging by clouds. The selection was made based on the identified knowledge gaps in the scientific understanding of these processes and/or their current representation in ESMs, as well as a novel perturbed parameter ensemble approach to detecting potential structural deficiencies in an ESM. Here, we review the state-of-the-art, outline our approach for arriving at recommendations for improving the representation of key aerosol and cloud processes within ESMs, and then provide such recommendations applicable in models operating at the Earth system scale. The limitations of the recommendations, applicability, as well as alternative approaches and future research directions are discussed. Overall, the findings highlight the need for continuous efforts towards smart ways for representing the aerosol number size distribution as well as consistent representations of key parameters (e.g., liquid water content and cloud droplet number concentration). Furthermore, we provide guidance for future ESM evaluation emphasising, in particular, the need for exploring the consistency of key parameters, process-based (as opposed to parameter-based), and the complementarity of in-situ and remote-sensed measurements for model evaluation.
Oussama Khemis, Gabriel Racovițeanu, Elena Vulpașu
The presence of pharmaceutical micropollutants from different families in water has become a serious environmental and human health problem. The treatment processes used to eliminate pharmaceutical pollutants are limited, and only some areeffective in removing certain pharmaceutical substances. Our study focused on reducing the pharmaceutical substance acetylsalicylic acid intended for human consumption at various concentrations (1.6 mg/l, 0.8 mg/l, and 0.4 mg/l organic matter (TOC)). The study was developed on two treatment processes (ozonation process (O3) and adsorption process with granular actif carbon) and two different flow rates (1.25 l/min with an EBCTof 6 min, 2.5 l/min with an EBCT of 3 min) applied in a large-scale drinking water treatment pilot.
The O3/AC process obtained good results at a flow rate of 1.25 l/min (EBCT of 6 min) with total elimination at a concentration of 0.4 mg/L and 98.73% and 99.96% for higher concentrations of 1.6 mg/l and 0.8 mg/l respectively, which means that this processis capable of degrading and removing the pharmaceutical substance acetylsalicylic acid.
Wassila Saiah, Amal Rabahi, Messaouda Boumaaza
et al.
This study investigates four novel iminocoumarin derivatives (3–6), previously synthesized and characterized, for their antioxidant, anti-inflammatory, and antidiabetic properties at different concentrations (12.5, 25, 50, 100, 200, 400, 800, and 1600 g/mL). Artificial neural network (ANN) approaches and response surface methodology (RSM) were used in a two-variable process that comprised iminocoumarins and concentrations to determine the impact of these compounds on the parameters that were monitored. The results indicated that the 2.2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay investigated the antioxidant activity of the synthesized compounds. The compounds expressed a remarkable DPPH inhibitory effect with IC₅₀ values in the range of 45.04 and 108.61 μg/ml. The anti-inflammatory activity was evaluated using an in vitro heat-induced hemolysis method. At 400 μg/ml, the percentage of erythrocyte hemolysis inhibition of these compounds ranged from 18.23 ± 0.18 % to 64.52 ± 0.13 %. The antidiabetic activity was determined in vitro by the alpha-glucosidase and alpha-amylase inhibitory effects. The synthesized compounds were found to be potent inhibitors of alpha-glucosidase with IC₅₀ values ranging between 111.25 μg/ml and 337.2 μg/ml and alpha-amylase with IC₅₀ values ranging between 101.84 μg/ml and 339.81 μg/ml. Additionally, the synthesized compounds underwent a molecular docking study against alpha-amylase. Moreover, there is a good correlation between experimental data and the ANN and RSM models. The R2 values for the inhibition of DPPH, alpha-glucosidase, alpha-amylase, and inflammation are 99.50 %, 98.96 %, 99.69 %, and 99.84 %, respectively; it is demonstrating the artificial neural network model's notable better accuracy and excellent agreement with the experimental findings. Thereby, the prepared molecules could serve as potential agents for the development of more powerful and effective antioxidants, anti-inflammatories, and antidiabetic compounds.
<p>Commercial microwave links (CMLs) are opportunistic rainfall sensors that provide indirect rainfall estimates from attenuation data. This is achieved by separating raindrop path attenuation from observed total loss and converting it to rainfall intensity using the <span class="inline-formula"><i>k</i>−<i>R</i></span> formula. Various methods have been proposed for CML rainfall retrieval using either attenuation data alone or additional environmental variables. However, most studies evaluate CML rainfall estimates deterministically and do not reveal how individual processing steps and variables affect rainfall estimation uncertainty. This study proposes to evaluate CML processing using an information-theoretic framework and demonstrates this probabilistic concept on two particular problems. The first analysis reveals the reduction of uncertainty in CML rainfall estimates by measuring the information content of individual variables and their combinations. Both quantitative and qualitative predictors are used, including sensor variables such as CML signal attenuation, and environmental variables such as temperature, or synoptic types. The rainfall intensity derived from the <span class="inline-formula"><i>k</i>−<i>R</i></span> formula and combined with synoptic type forms an informative combination of sensor and environmental variables for reducing uncertainty regarding reference rainfall intensity. The second analysis demonstrates the application of information theory for classifying wet and dry periods using signal attenuation data and other environmental variables. In a limited single-link evaluation, a non-parametric model indicated better performance than the reference approaches suggesting the potential of information theory in CML processing. The proposed framework enables the identification of informative sensor and environmental variables, the evaluation of the effects of different processing steps on the estimated rainfall intensity, or the development of a wet-dry classification model calibrated in a probabilistic manner ultimately facilitating the improvement of CML rainfall estimates.</p>
Asaad M. Armanuos, Martina Zeleňáková, Hany F. Abd-Elhamid
et al.
Abstract Seawater intrusion (SWI) poses a continuing threat to the sustainability of groundwater resources in coastal aquifers, especially in areas where demand for freshwater is high. Among the various engineering approaches, underground dams as physical barriers are commonly used to restrict the inland migration of seawater into coastal aquifers. However, their effectiveness can be significantly affected by structural design and groundwater extraction practices. This research implements the SEAWAT numerical code to investigate the performance of a double-fractured underground dam across changing hydrological conditions. The analysis emphasises the influence of fracture aperture and height, underground dam depth and location and the abstraction well depth, location and abstraction rate. Two representative case studies were analysed: the Henry problem, serving as a benchmark, and the Akrotiri coastal aquifer in Cyprus, demonstrating a real-world case study. The outcomes show that dam efficiency decreases significantly when underground dams are located closer to the seawater boundary, or when dam fractures are positioned close to the base of the aquifer. High pumping rates and a location of the well near the seawater-freshwater interface increase the loss of efficiency, while high saltwater density exacerbates these impacts. The study also demonstrates that dam location has a greater effect on efficiency than its depth. Overall, the outcomes highlight the lack of specific design criteria and strategies for carefully considering groundwater abstraction and the long-term importance of underground dams for coastal groundwater management. The findings provide practical insights for coastal aquifer management, offering guidance for more sustainable utilisation of groundwater resources in vulnerable coastal regions.
Pierre Lechevallier, Günter Gruber, Vojtěch Bareš
et al.
Abstract A major challenge in wastewater and sewer system monitoring is the development of advanced sensing technologies to improve standard pollutant measurement and allow real-time online detection of emerging contaminants. This study presents a dataset from a 25-week measurement campaign comparing a novel hyperspectral imaging system to state-of-the-art ultraviolet-visible (UV-vis) sensors. The dataset includes 5801 hyperspectral images of raw wastewater, measurements of temperature, ammonium, flow, turbidity, pH, and UV-vis absorbance spectra, as well as 533 grab samples analyzed for conventional pollutants. We also gathered 86 samples after four rain events and analyzed them for twenty organic chemicals, providing insights into the impact of wet weather on pollutant levels. The data collection and processing methodologies are detailed, along with visualizations and analysis. Despite difficulties in the maintenance of some sensors, in particular the ion-selective electrode for ammonium measurement, the dataset’s high temporal resolution, the time span of 25 weeks, and the extensive range of analyzed pollutants make it a valuable resource for advancing the field of urban water management.
Ștefan-Dragoș Găitănaru, Iulian Iancu, Sanda-Carmen Georgescu
et al.
Due to the increased development of urban areas and climate change, water resource management is gaining more attention. Among the most important aspects under scrutiny is improving the reliability of water resources. In this paper, the focus is on the dynamic modelling of a well field in EPANET. By dynamic modelling, we mean that the numerical model can adjust the water levels in the wells with respect to the extracted flow rate, according to the results of the hydrogeological study of the area. The operation of a well field must sometimes be realized at partial loads. In this latter case, all the duty points of the pumps in operation change and the flow rates may exceed the maximum allowed values, leading to the rapid clogging of the wells. The model and results obtained for different operating scenarios will be presented in the paper.
A. Løkkegaard, A. Løkkegaard, K. D. Mankoff
et al.
<p>Here, we present a compilation of 95 ice temperature profiles from 85 boreholes from the Greenland ice sheet and peripheral ice caps, as well as local ice caps in the Canadian Arctic. Profiles from only 31 boreholes (36 %) were previously available in open-access data repositories. The remaining 54 borehole profiles (64 %) are being made digitally available here for the first time. These newly available profiles, which are associated with pre-2010 boreholes, have been submitted by community members or digitized from published graphics and/or data tables. All 95 profiles are now made available in both absolute (meters) and normalized (0 to 1 ice thickness) depth scales and are accompanied by extensive metadata. These metadata include a transparent description of data provenance. The ice temperature profiles span 70 years, with the earliest profile being from 1950 at Camp VI, West Greenland. To highlight the value of this database in evaluating ice flow simulations, we compare the ice temperature profiles from the Greenland ice sheet with an ice flow simulation by the Parallel Ice Sheet Model (PISM). We find a cold bias in modeled near-surface ice temperatures within the ablation area, a warm bias in modeled basal ice temperatures at inland cold-bedded sites, and an apparent underestimation of deformational heating in<span id="page3830"/> high-strain settings. These biases provide process level insight on simulated ice temperatures.</p>
La humanidad, es capaz de satisfacer sus necesidades aprovechando todos los recursos naturales renovables a su alcance. Los recursos naturales renovables tienen un valor actual y potencial, pues son componentes de la naturaleza. Los cuales son: Físicos: sol, aire y agua; Biológicos: suelo animales y plantas, de los cuales en algún grado depende la vida de los seres vivos, sin embargo en Guatemala cada día son más escasos, por el mal uso y aprovechamiento que hacemos de ellos. Esta investigación, pretende aprovechar en su totalidad el recurso agua, pues se plantea la reutilización de la misma, después de haber sido tratada por medio de una planta de tratamiento de aguas residuales, que dada su importancia requiere sistemas de canalización, tratamiento, descarga y reuso. Toda agua servida o residual debe ser tratada tanto para proteger la salud pública, como para preservar el medio ambiente, pues su tratamiento nulo o indebido genera graves problemas de contaminación. Las aguas residuales, constituyen un residuo que no se utiliza, proveniente del uso doméstico, en el presente caso. Están constituidas por todas aquellas aguas que son conducidas por el alcantarillado universitario e incluyen, a veces, las aguas de lluvia y las infiltraciones de agua del terreno en el que se encuentra la planta de tratamiento de la Universidad de San Carlos de Guatemala. Sin embargo se tiene la oportunidad de reciclar la materia prima que es el agua y reutilizarla en el riego de las áreas verdes de la Universidad de San Carlos de Guatemala, evaluando los beneficios que esto conlleva, beneficio económico y ambiental, sin comprometer la satisfacción de la necesidad de riego para las generaciones futuras. Para ello se hace necesario realizar un análisis de los parámetros de agua residual conforme la ley de Descargas vigente, Acuerdo gubernativo 236 – 2006 Reglamento de descargas y reuso de aguas residuales y disposición de lodos, para determinar la calidad del agua y sus posibles usos en la universidad, así como la propuesta para dicha reutilización.
Este artículo trata sobre la metodología utilizada para determinar el tiempo de retención del sistema lagunar de la planta piloto de la Escuela Regional de Ingeniería Sanitaria y Recursos Hidráulicos – ERIS- de la Universidad de San Carlos de Guatemala. El procedimiento utilizado para determinar el tiempo de retención de las lagunas se obtuvo por medio de la aplicación de Cloruro de Sodio (NaCl) o sal común como sustancia trazadora, la cual fue aplicada a la entrada de la laguna con una concentración conocida y medida en la salida con un conductivímetro cada 12 horas durante 44 días. Los valores obtenidos de concentraciones son procesados y graficados en función del tiempo transcurrido, y utilizando modelos matemáticos se obtienen las características hidráulicas de las lagunas, tipo de flujo, zonas muertas, y cortocircuitos. Con la prueba se obtuvo que el tiempo de retención de la laguna de estabilización es de 23 días y en la laguna de maduración es de 36 días. Comparando estos resultados con los valores de tiempos de retención teóricos se tiene una diferencia de 3 días más en la laguna de estabilización y 7 días más en la laguna de maduración, además que las dos lagunas funcionan con flujo pistón y flujo mezclado en una relación 1:4 respectivamente.
Debido al estrés hídrico que se atraviesa, pensar en el hecho del reaprovechamiento de las aguas residuales es imperativo. Este estudio caracterizó y valorizó el agua residual generada en el proceso de beneficiado húmedo. Se muestreó en uno de los beneficios exportadores de café de la comunidad de La Libertad, en el municipio de La Democracia, en el departamento de Huehuetenango, Guatemala. El objetivo fue determinar su calidad y el tratamiento adecuado para su reuso. Los resultados se compararon con los valores recomendados en el acuerdo gubernativo 236- 2006 del Ministerio de Ambiente de la República de Guatemala. Se determinó que no son aptas para poder ser descargada a cuerpos receptores. Por lo cual todas deben ser tratadas. Adicionalmente, se analizó la biodegradabilidad y como resultado se obtuvo que todas pueden ser tratadas por métodos biológicos. Se determinó que las aguas residuales provenientes del despulpado y lavado poseen potencialmente un valor agregado si son utilizadas en el riego de cultivos debido a su alta concentración de nutrientes. El agua residual de despulpado tiene 12 mg/L y 53 mg/L de fósforo total y nitrógeno total respectivamente. Por su parte, el agua residual de lavado por recirculado tiene, 3308 mg/L fósforo total y 117 mg/L de nitrógeno total.
Abstract. Plant hydraulics gains increasing interest in plant eco-physiology and vegetation modeling. However, the hydraulic properties and profiles are often improperly represented thus leading to biased results and simulations, e.g., the neglection of gravitational pressure drop results in overestimated water flux. We highlight the commonly seen ambiguities and/or misunderstandings in plant hydraulics, including (1) distinction between water potential and pressure, (2) differences among hydraulic conductance and conductivity, (3) xylem vulnerability curve formulations, (4) stomatal model representations, (5) bias from analytic estimations, (6) whole plant vulnerability, and (7) neglected temperature dependencies. We recommend careful thinking before using or modifying existing definitions, methods, and models.
Vertical concentration distributions of solids conveyed in Newtonian fluids can be modelled using Rouse-Schmidt type distributions. Observations of solids conveyed in turbulent low Reynolds number visco-plastic carriers, suggest that solids are more readily suspended than their Newtonian counterparts, producing higher concentrations in the centre of the pipe. A Newtonian concentration profile model was adapted to include typical turbulent viscosity distributions within the pipe and particle motion calculated using non-Newtonian sheared settling. Predictions from this and the unmodified model, using the same wall viscosity, are compared with the chord averaged profile extracted from tomographic data obtained using a 50 mm horizontal pipe.
<p>Opportunistic sensing of rainfall and water vapor
using commercial microwave links operated within cellular networks was
conceived more than a decade ago. It has since been further investigated
in numerous studies, predominantly concentrating on the frequency region
of 15–40 GHz. This article provides the first evaluation of rainfall
and water vapor sensing with microwave links operating at E-band frequencies
(specifically 71–76 and 81–86 GHz). These microwave links are increasingly being
updated (and are frequently replacing) older communication infrastructure.
Attenuation–rainfall relations are investigated theoretically on drop
size distribution data. Furthermore, quantitative rainfall estimates
from six microwave links, operated within cellular backhaul, are
compared with observed rainfall intensities. Finally, the capability to
detect water vapor is demonstrated on the longest microwave link
measuring 4.86 km in path length. The results show that E-band microwave
links are markedly more sensitive to rainfall than devices operating in
the 15–40 GHz range and can observe even light rainfalls, a feat
practically impossible to achieve previously. The E-band links are,
however, substantially more affected by errors related to variable drop
size distribution. Water vapor retrieval might be possible from long
E-band microwave links; nevertheless, the efficient separation of
gaseous attenuation from other signal losses will be challenging in
practice.</p>
Edwin Moisés Oviedo Acuña, Félix Alan Douglas Aguilar Carrera
El presente artículo evalúa el efecto que produce la carga hidráulica, sobre la remoción nitrógeno total y fósforo total en un fotobiorreactor (FB) instalado en la planta de tratamiento de aguas residuales de la Universidad de San Carlos de Guatemala. El FB fue alimentado por la fuente del filtro percolador de la etapa III y expuesto a radiación solar durante los meses de marzo a mayo, periodo del cual se reportan crecimientos de algas del tipo Chlorella. Se construyeron tres fotobiorreactores, los que trabajaron a cargas hidráulicas: baja (FBHB), media (FBHM), alta (FBHA), a condiciones de flujo continuo y batch. Las cargas hidráulicas evaluadas fueron de 1.32, 3.23, 5.32 m3/m2/día. El crecimiento máximo de algas del tipo Chlorella se obtuvo al séptimo día alcanzándose un valor de 3.2x106 cel/mL en el FBHM, en el FBHB un valor de 2.4x106 cel/mL y en el FBHA un valor de 2.56x106 cel/mL. La concentración promedio de nitrógeno total a la entrada de los FB trabajando a flujo continuo fue de 71.67 mg/L; en la salida del FBHB 65.67 mg/L; en las salida del FBHM, 63.00 mg/L; en el FBHA de 60.67 mg/L. La eficiencia de remoción de 8.37 %, 12.09 %, y 15.35 % respectivamente. El comportamiento del fotobiorreactor trabajando a flujo tipo batch mostró eficiencias similares, siendo estas de 17.65 % para el FBHB, 15.09 % para el FBHM, y 18.67 % para el FBHA. En el caso del fósforo total la concentración de entrada en los FB trabajando a flujo continuo fue de 14.77 mg/L; en la salidas del FBHB de 8.27 mg/L; para el FBHM de 5.00 mg/L; para el FBHA de 5.57 mg/L. Con eficiencias de remoción de 44.02 %, 66.14 % y 62.30 % respectivamente. La concentración de fósforo en la entrada de los FB trabajando con flujo tipo batch fue de 12.87 mg/L, en la salidas del FBHB fue de 13.87 mg/L, para el FBHM de 11.18 mg/L; para el FBHA de 10.15 mg/L, con eficiencias de remoción de -7.77 %, 13.08 % y 21.11 % respectivamente.
Este artículo presenta un procedimiento de aislamiento e identificación de bacterias con actividad lipolítica aisladas de la planta de tratamiento de aguas residuales (PTAR) de la Universidad de San Carlos de Guatemala. Las muestras fueron tomadas en cinco puntos diferentes durante los meses de julio, agosto y septiembre de 2016. Se aislaron treinta y cinco cepas con actividad lipolítica utilizando tributirina como sustrato. Se evidenció la actividad lipolítica en agar tributirina de estas cepas, de las cuales se identificaron veinte. Las especies bacterianas identificadas corresponden a dieciocho cepas Gram negativo y dos cepas Gram positivo. Entre las especies identificadas se encuentran: Serratia marcescens, Acinetobacter baumannii/calcoaceticus, Acinetobacter junii/johnsonii, Comamonas testosteroni, Pseudomonas aeruginosa, Pseudomonas alcaligenes, Pseudomonas putida, Pseudomonas fluorescens, Aeromonas sobria, Aeromonas hydrophila/caviae, Pasteurella aerogenes, Pasteurella spp., Chromobacterium violaceum, Bacillus subtillis/amyloliquefaciens y Bacillus coagulans.
Esta investigación tuvo como fin establecer una relación entre los períodos de sequía meteorológica en el corredor seco hondureño y los eventos de El Niño de las últimas cinco décadas, para pronosticar futuros períodos de sequía. Para ello se hizo una revisión y selección de las series de datos de lluvia mensual de 13 estaciones pluviométricas disponibles en el área de estudio. Posteriormente, se utilizó el método de índice normalizado de precipitación (SPI) y se obtuvieron los eventos de sequía mensuales para 16 años en los cuales se asumió que el régimen de lluvia se vio afectado debido a un evento de El Niño, entre mayo de 1972 y abril de 2017. Se estableció una relación entre los años en donde se registró un evento de El Niño en el mes de enero y los períodos de sequía que le siguieron en el mismo año. A partir de esta relación se concluye que es 68 % probable que exista un período de sequía en el año, si se pronostica para el mes de enero, un evento de El Niño.
Este artículo presenta los resultados de un bioensayo realizado como prueba piloto para el proceso de recolección, tratamiento y aplicación de orina humana como fertilizante orgánico en plantas de maíz para determinar sus efectos. Los resultados y lecciones aprendidas del bioensayo indican que con el almacenamiento de la orina, alcanza valores de pH mayores a 8 lo que elimina la posible presencia de patógenos, y es una fuente de concentraciones de nitrógeno (N) de 3.00-7.00 g/L, fósforo (P) 0.20-0.50 g/L y potasio (K) de 0.90-4.88 g/L. Al separar la orina que corresponde al uno por ciento de las aguas residuales, se determinó el impacto de la orina sobre las mismas, al analizar los siguientes parámetros demanda bioquímica de oxígeno (DBO5), demanda química de oxígeno (DQO), nitrógeno (N), fósforo (P). La orina contribuye en un 7.11% en la demanda bioquímica de oxígeno (DBO5), 9.67% en la demanda química de oxígeno (DQO), 9.35% nitrógeno (N) y 16.37% fósforo (P) de las aguas residuales
Celia María Grajeda Figueroa, Adán Pocasangre Collazos
Este artículo trata sobre la determinación de impactos ambientales, producto de la operación de una planta de tratamiento de aguas residuales mediante el sistema lodos activados, la cual trata específicamente descargas provenientes de un sector residencial, mediante la metodología ACV (análisis de ciclo de vida) ambiental, con la finalidad de valorar los impactos potenciales al ambiente y la salud; contribuyendo los valores obtenidos, a la generación de base de datos para comparar alternativas de tratamiento. Las categorías de impacto abarcadas en la investigación son: agotamiento de recursos abióticos, cambio climático, eutrofización e índice de carga contaminante. Se obtuvo los siguientes resultados: índice de cambio climático (CCI) de 0.76 kg/m³ de CO₂ equivalente, potencial de eutrofización (PE) del afluente de 0.34 kg de PO₄ˉ³ equivalente, (PE) de efluente de 0.072 kg de PO₄ˉ³ equivalente, agotamiento de recursos abióticos (AR) de 3.46 MJ Sb equivalente por m³, e índice de carga contaminante (ICC) de 55.10, para la categoría de contaminación hacia el cuerpo receptor.
<p>For more than two decades, research groups in hydrology, ecology, soil
science, and biogeochemistry have performed cryogenic water extractions (CWEs) for
the analysis of <i>δ</i><sup>2</sup>H and <i>δ</i><sup>18</sup>O of soil water.
Recent studies have shown that extraction conditions (time, temperature, and
vacuum) along with physicochemical soil properties may affect extracted soil
water isotope composition. Here we present results from the first worldwide
round robin laboratory intercomparison. We test the null hypothesis that, with
identical soils, standards, extraction protocols, and isotope analyses,
cryogenic extractions across all laboratories are identical. Two standard
soils with different physicochemical characteristics along with deionized
(DI) reference water of known isotopic composition were shipped to 16
participating laboratories. Participants oven-dried and rewetted the soils to
8 and 20 % gravimetric water content (WC), using the deionized reference
water. One batch of soil samples was extracted via predefined extraction
conditions (time, temperature, and vacuum) identical to all laboratories; the
second batch was extracted via conditions considered routine in the
respective laboratory. All extracted water samples were analyzed for
<i>δ</i><sup>18</sup>O and <i>δ</i><sup>2</sup>H by the lead laboratory (Global
Institute for Water Security, GIWS, Saskatoon, Canada) using both a laser and an
isotope ratio mass spectrometer (OA-ICOS and IRMS, respectively). We rejected
the null hypothesis. Our results showed large differences in retrieved
isotopic signatures among participating laboratories linked to soil type and
soil water content with mean differences compared to the reference water ranging from
+18.1 to −108.4 ‰ for <i>δ</i><sup>2</sup>H and +11.8 to
−14.9 ‰ for <i>δ</i><sup>18</sup>O across all laboratories. In
addition, differences were observed between OA-ICOS and IRMS isotope data.
These were related to spectral interferences during OA-ICOS analysis that are
especially problematic for the clayey loam soils used. While the types of
cryogenic extraction lab construction varied from manifold systems to single
chambers, no clear trends between system construction, applied extraction
conditions, and extraction results were found. Rather, observed differences
in the isotope data were influenced by interactions between multiple factors
(soil type and properties, soil water content, system setup, extraction
efficiency, extraction system leaks, and each lab's internal accuracy). Our
results question the usefulness of cryogenic extraction as a standard for
water extraction since results are not comparable across laboratories. This
suggests that defining any sort of standard extraction procedure applicable
across laboratories is challenging. Laboratories might have to establish
calibration functions for their specific extraction system for each natural
soil type, individually.</p>