{"title":"The role of hydropedology when aiming for the United Nations Sustainable Development Goals","authors":"J. Bouma","doi":"10.1002/vzj2.20269","DOIUrl":"https://doi.org/10.1002/vzj2.20269","url":null,"abstract":"","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43238502","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
On the cover: A 3D data visualization of the elevation in the Schöfertal catchment (Germany). The digital elevation data are the primary source of information to quantify the data-related uncertainty of spatial soil moisture patterns estimated using an unsupervised multiple regression approach. See Paasche et al., “Quantification of data-related uncertainty of spatially dense soil moisture patterns on the small catchment scale estimated using unsupervised multiple regression,” https://doi.org/10.1002/vzj2.20258. Photo credit: Ingmar Schröter (CC-BY-SA 4.0).
{"title":"Cover Image, Volume 22, Issue 4","authors":"","doi":"10.1002/vzj2.20271","DOIUrl":"https://doi.org/10.1002/vzj2.20271","url":null,"abstract":"<b>On the cover</b>: A 3D data visualization of the elevation in the Schöfertal catchment (Germany). The digital elevation data are the primary source of information to quantify the data-related uncertainty of spatial soil moisture patterns estimated using an unsupervised multiple regression approach. See Paasche et al., “Quantification of data-related uncertainty of spatially dense soil moisture patterns on the small catchment scale estimated using unsupervised multiple regression,” https://doi.org/10.1002/vzj2.20258. Photo credit: Ingmar Schröter (CC-BY-SA 4.0).","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":"61 5","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138505131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Maintaining the editorial standards of a scientific journal is the primary task of the journal editors. Their task is made much easier with the help of colleagues who are invited to review manuscripts. Through their critical comments and helpful suggestions, these volunteer reviewers have done much to maintain and further the quality of research reported in Vadose Zone Journal. The members of the VZJ Editorial Board express their appreciation to the following individuals who reviewed one or more manuscripts during the past year. Every effort was made to compile an accurate list from our records. We extend our apologies and thanks to any reviewers whose names have not been included.
{"title":"Thanks to Reviewers, Vadose Zone Journal, 2022","authors":"","doi":"10.1002/vzj2.20261","DOIUrl":"https://doi.org/10.1002/vzj2.20261","url":null,"abstract":"Maintaining the editorial standards of a scientific journal is the primary task of the journal editors. Their task is made much easier with the help of colleagues who are invited to review manuscripts. Through their critical comments and helpful suggestions, these volunteer reviewers have done much to maintain and further the quality of research reported in Vadose Zone Journal. The members of the VZJ Editorial Board express their appreciation to the following individuals who reviewed one or more manuscripts during the past year. Every effort was made to compile an accurate list from our records. We extend our apologies and thanks to any reviewers whose names have not been included.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45246436","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Bromide is a frequently used conservative tracer in soil leaching studies, including studies on contaminant leaching from arable topsoils. However, bromide often does not behave conservatively. Biogeochemists have known for many years that in natural soils, bromide is converted into organic bromine in a process known as bromination. However, bromination is seldom used as an explanation of non‐conservative leaching behavior by soil hydrologists. In a controlled small‐scale lysimeter study with arable soil we demonstrate such nonconservative behavior of bromide in opposition to control columns with fine gravel/coarse sand. By combining a literature review with the lysimeter study, we demonstrate the potential importance of bromination in topsoil and that bromination cannot be ignored, when interpreting bromide tracer experiments in arable soils. We also highlight the need for further studies on the processes of bromination and remineralization, to be able to account for these when conducting bromide leaching assessments.
{"title":"Bromide reactivity in topsoil: Implications for use as a “conservative” tracer in assessing quantity and quality of water","authors":"C. Albers, A. Rosenbom","doi":"10.1002/vzj2.20260","DOIUrl":"https://doi.org/10.1002/vzj2.20260","url":null,"abstract":"Bromide is a frequently used conservative tracer in soil leaching studies, including studies on contaminant leaching from arable topsoils. However, bromide often does not behave conservatively. Biogeochemists have known for many years that in natural soils, bromide is converted into organic bromine in a process known as bromination. However, bromination is seldom used as an explanation of non‐conservative leaching behavior by soil hydrologists. In a controlled small‐scale lysimeter study with arable soil we demonstrate such nonconservative behavior of bromide in opposition to control columns with fine gravel/coarse sand. By combining a literature review with the lysimeter study, we demonstrate the potential importance of bromination in topsoil and that bromination cannot be ignored, when interpreting bromide tracer experiments in arable soils. We also highlight the need for further studies on the processes of bromination and remineralization, to be able to account for these when conducting bromide leaching assessments.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46313786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Newell, Emily B. Stockwell, Jessica Alanis, D. Adamson, Kenneth L. Walker, R. Anderson
Soil‐to‐groundwater contaminant mass discharge (Md) is the authoritative metric defining source strength at sites impacted by per‐ and polyfluoroalkyl substances (PFAS) and is increasingly being reported. Accurate estimates of groundwater recharge at representative spatial scales, however, is critical to quantitatively estimating Md, which to date has received comparatively little attention relative to PFAS‐specific partitioning and retention processes within unsaturated zone source areas despite a plethora of available literature. The objective of this review is to summarize the concept of Md as it applies to PFAS‐impacted sites, present standardized terminology, and collate published literature on groundwater recharge for a practitioner‐level summary of practical methods. Critically, the primary aim is to reduce uncertainty in recharge (and, thus, Md) estimates commensurate to a given site management application (i.e., the data quality objective process). Therefore, we propose a tiered system of increasing cost, complexity, and certainty depending on specific project requirements and site conditions and recommend applicable recharge methods for each tier based on these factors. Ultimately, a framework is presented for the assessment of PFAS‐impacted source areas based on the concept of Md.
{"title":"Determining groundwater recharge for quantifying PFAS mass discharge from unsaturated source zones","authors":"C. Newell, Emily B. Stockwell, Jessica Alanis, D. Adamson, Kenneth L. Walker, R. Anderson","doi":"10.1002/vzj2.20262","DOIUrl":"https://doi.org/10.1002/vzj2.20262","url":null,"abstract":"Soil‐to‐groundwater contaminant mass discharge (Md) is the authoritative metric defining source strength at sites impacted by per‐ and polyfluoroalkyl substances (PFAS) and is increasingly being reported. Accurate estimates of groundwater recharge at representative spatial scales, however, is critical to quantitatively estimating Md, which to date has received comparatively little attention relative to PFAS‐specific partitioning and retention processes within unsaturated zone source areas despite a plethora of available literature. The objective of this review is to summarize the concept of Md as it applies to PFAS‐impacted sites, present standardized terminology, and collate published literature on groundwater recharge for a practitioner‐level summary of practical methods. Critically, the primary aim is to reduce uncertainty in recharge (and, thus, Md) estimates commensurate to a given site management application (i.e., the data quality objective process). Therefore, we propose a tiered system of increasing cost, complexity, and certainty depending on specific project requirements and site conditions and recommend applicable recharge methods for each tier based on these factors. Ultimately, a framework is presented for the assessment of PFAS‐impacted source areas based on the concept of Md.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45916523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Evapotranspiration (ET) surface barriers store infiltrated precipitation during the recharge period and release the stored water to the atmosphere via ET. The primary purpose of a surface barrier is to reduce or eliminate drainage to the underlying waste zone. The objective of this study is to analyze the spatial and temporal dynamics of soil moisture within an ET surface barrier based on observed and simulated data. This study characterizes the water movement processes using contour plots of soil moisture content and flux rate in the depth‐time domain. Zero‐flux planes (ZFPs) divide the depth‐time domain into stored water, ET, and drainage zones. Some flow dynamics (e.g., flow rate and direction) that were not observed in the field were elaborated with simulation results to identify the depth of the recharge front of infiltrated water, the release front of stored water, and the bottom of the ET zone. The ET‐drainage divide marks the bottom of the ET zone and the top of the drainage zone. The results showed that the temporal analysis of soil moisture storage could indicate the degree of usage of the storage capacity of a surface barrier. The spatial‐temporal analyses of soil moisture content and flux rate can characterize the durations of the recharge/release processes and the depth of the stored water. Quantification of these processes and related zones provides beneficial understanding of the state and dynamics of soil moisture for a range of weather and vegetation conditions and is useful in optimizing the design of an ET surface barrier.
{"title":"Delineating soil moisture dynamics within an evapotranspiration surface barrier using spatial‐temporal analysis","authors":"Z. Zhang, S. Mehta, M. Bergeron","doi":"10.1002/vzj2.20256","DOIUrl":"https://doi.org/10.1002/vzj2.20256","url":null,"abstract":"Evapotranspiration (ET) surface barriers store infiltrated precipitation during the recharge period and release the stored water to the atmosphere via ET. The primary purpose of a surface barrier is to reduce or eliminate drainage to the underlying waste zone. The objective of this study is to analyze the spatial and temporal dynamics of soil moisture within an ET surface barrier based on observed and simulated data. This study characterizes the water movement processes using contour plots of soil moisture content and flux rate in the depth‐time domain. Zero‐flux planes (ZFPs) divide the depth‐time domain into stored water, ET, and drainage zones. Some flow dynamics (e.g., flow rate and direction) that were not observed in the field were elaborated with simulation results to identify the depth of the recharge front of infiltrated water, the release front of stored water, and the bottom of the ET zone. The ET‐drainage divide marks the bottom of the ET zone and the top of the drainage zone. The results showed that the temporal analysis of soil moisture storage could indicate the degree of usage of the storage capacity of a surface barrier. The spatial‐temporal analyses of soil moisture content and flux rate can characterize the durations of the recharge/release processes and the depth of the stored water. Quantification of these processes and related zones provides beneficial understanding of the state and dynamics of soil moisture for a range of weather and vegetation conditions and is useful in optimizing the design of an ET surface barrier.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-05-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45985314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Rooting in deep regolith enables forests to withstand seasonal and annual precipitation shortfalls. Despite its ecological importance, spatial patterns in regolith thickness within forest ecosystems are scarcely documented. Regolith thickness was estimated at 66 sites throughout a 543‐ha watershed in the southern Sierra Nevada by hand auger to point of failure or a maximum depth of 7.5 m, describing a minimum thickness estimate. Regolith consists of 1–2 m of soil overlying thick and porous weathered granodiorite. Depth to auger failure ranged from 1.52 to an indeterminate depth beyond 7.5 m. A total of 27 points exceeded 7.5 m depth. Normal, lognormal, and gamma data distribution models were fitted to observations to extrapolate thickness across the watershed and estimate thicknesses beyond the measurement limitation. Predictions for the 95th percentile of regolith thickness varied substantially; 26.05 m for lognormal, 16.87 m for gamma, and 9.56 m for normal. Considering any best fit model, >55% of the watershed area was deeper than 5 m. Depth classes were formed to evaluate the extent to which topography is associated with spatial trends in regolith thickness. Spatial patterns were related to two covariate proxies (distance from stream channel and topographic wetness) with the general landscape trend of shallow depth classes (<3.3 m) in lowlands and deeper regolith classes (>7.5 m) in uplands. The normalized difference vegetation index signatures over the late stages of a 5‐year drought were greener in the lowlands. In contrast, upland forests displayed widespread tree die‐off, suggesting deep water storage does not maintain forests over long‐term drought.
{"title":"Trends in regolith thickness in a headwater catchment, Sierra Nevada, California","authors":"R. Ferrell, Scott M. Devine, A. O’Geen","doi":"10.1002/vzj2.20259","DOIUrl":"https://doi.org/10.1002/vzj2.20259","url":null,"abstract":"Rooting in deep regolith enables forests to withstand seasonal and annual precipitation shortfalls. Despite its ecological importance, spatial patterns in regolith thickness within forest ecosystems are scarcely documented. Regolith thickness was estimated at 66 sites throughout a 543‐ha watershed in the southern Sierra Nevada by hand auger to point of failure or a maximum depth of 7.5 m, describing a minimum thickness estimate. Regolith consists of 1–2 m of soil overlying thick and porous weathered granodiorite. Depth to auger failure ranged from 1.52 to an indeterminate depth beyond 7.5 m. A total of 27 points exceeded 7.5 m depth. Normal, lognormal, and gamma data distribution models were fitted to observations to extrapolate thickness across the watershed and estimate thicknesses beyond the measurement limitation. Predictions for the 95th percentile of regolith thickness varied substantially; 26.05 m for lognormal, 16.87 m for gamma, and 9.56 m for normal. Considering any best fit model, >55% of the watershed area was deeper than 5 m. Depth classes were formed to evaluate the extent to which topography is associated with spatial trends in regolith thickness. Spatial patterns were related to two covariate proxies (distance from stream channel and topographic wetness) with the general landscape trend of shallow depth classes (<3.3 m) in lowlands and deeper regolith classes (>7.5 m) in uplands. The normalized difference vegetation index signatures over the late stages of a 5‐year drought were greener in the lowlands. In contrast, upland forests displayed widespread tree die‐off, suggesting deep water storage does not maintain forests over long‐term drought.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49398873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Multiple regression analysis is a valuable method to reduce information gaps in a sparse soil moisture data set by fusing its information content with those of densely mapped data sets. Regression analysis utilizing uncertain data results in an indeterminate regression model and indeterminate soil moisture predictions when applying the regression model. We employ an unsupervised multiple regression approaches, taking optimally located sparse soil moisture measurements directly as coefficients in a linear regression model. We propagate data uncertainties into our probabilistic soil moisture estimation results by embedding the regression in a Monte Carlo approach. The computed uncertainty defines the quantitative limit for information retrieval from the resultant ensemble of soil moisture maps. This raises doubts on the true presence of some prominent channel‐like features of increased soil moisture that are clearly visible in a previously and deterministically derived soil moisture map ignoring the presence of data uncertainty. The approach followed in this work is computationally simple and could be applied routinely to databases of similar size. Insufficient uncertainty communication by the data provider became the biggest obstacle in our efforts and led us to the insight that the geoscientific community may need to revise their standards with regard to uncertainty communication related to measured and processed data.
{"title":"Quantification of data‐related uncertainty of spatially dense soil moisture patterns on the small catchment scale estimated using unsupervised multiple regression","authors":"H. Paasche, Ingmar Schröter","doi":"10.1002/vzj2.20258","DOIUrl":"https://doi.org/10.1002/vzj2.20258","url":null,"abstract":"Multiple regression analysis is a valuable method to reduce information gaps in a sparse soil moisture data set by fusing its information content with those of densely mapped data sets. Regression analysis utilizing uncertain data results in an indeterminate regression model and indeterminate soil moisture predictions when applying the regression model. We employ an unsupervised multiple regression approaches, taking optimally located sparse soil moisture measurements directly as coefficients in a linear regression model. We propagate data uncertainties into our probabilistic soil moisture estimation results by embedding the regression in a Monte Carlo approach. The computed uncertainty defines the quantitative limit for information retrieval from the resultant ensemble of soil moisture maps. This raises doubts on the true presence of some prominent channel‐like features of increased soil moisture that are clearly visible in a previously and deterministically derived soil moisture map ignoring the presence of data uncertainty. The approach followed in this work is computationally simple and could be applied routinely to databases of similar size. Insufficient uncertainty communication by the data provider became the biggest obstacle in our efforts and led us to the insight that the geoscientific community may need to revise their standards with regard to uncertainty communication related to measured and processed data.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49657459","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jelte G. H. de Bruin, V. Bense, M. J. van der Ploeg
Permafrost regions are experiencing increasing air temperatures, accelerating the thawing process, and thickening the active layer in summer. This can accelerate the release of greenhouse gasses into the atmosphere from the organic carbon stored in the permafrost. The long‐term thawing rates of permafrost below the active layer are governed by the soil thermal properties, the heat capacity, and thermal conductivity, which vary due to differences in grain sizes and distribution and organic matter content. Using nine column experiments comprised of fully saturated synthetic permafrost samples exposed to freeze–thaw cycles, the relative contributions of a range of soil grain sizes and organic matter contents on the soil thermal properties were investigated. The columns were subjected to a freeze and thaw cycle while soil temperatures were recorded in profiles. To infer the thermal properties from these experimental data, a numerical heat transfer model was used. The best fit between the observations and a batch of 5544 numerical models was used to find optimum values for permafrost thermal properties. The optimized heat capacity varied between 500 and 650 (J/m3 K) and thermal conductivity between 2.45 and 3.55 (W/m K). These optimized parameters were subsequently used to model a 100‐year permafrost active layer thaw scenario under warming air temperatures. Variations in the optimized thermal properties resulted in a time difference in thawing depth of 10–15 years and thawing depths varied between 9 and 10 m between the different optimized thermal properties at the end of the 100‐year scenario.
{"title":"Soil thermal properties during freeze–thaw dynamics as function of variable organic carbon and grain size distribution","authors":"Jelte G. H. de Bruin, V. Bense, M. J. van der Ploeg","doi":"10.1002/vzj2.20252","DOIUrl":"https://doi.org/10.1002/vzj2.20252","url":null,"abstract":"Permafrost regions are experiencing increasing air temperatures, accelerating the thawing process, and thickening the active layer in summer. This can accelerate the release of greenhouse gasses into the atmosphere from the organic carbon stored in the permafrost. The long‐term thawing rates of permafrost below the active layer are governed by the soil thermal properties, the heat capacity, and thermal conductivity, which vary due to differences in grain sizes and distribution and organic matter content. Using nine column experiments comprised of fully saturated synthetic permafrost samples exposed to freeze–thaw cycles, the relative contributions of a range of soil grain sizes and organic matter contents on the soil thermal properties were investigated. The columns were subjected to a freeze and thaw cycle while soil temperatures were recorded in profiles. To infer the thermal properties from these experimental data, a numerical heat transfer model was used. The best fit between the observations and a batch of 5544 numerical models was used to find optimum values for permafrost thermal properties. The optimized heat capacity varied between 500 and 650 (J/m3 K) and thermal conductivity between 2.45 and 3.55 (W/m K). These optimized parameters were subsequently used to model a 100‐year permafrost active layer thaw scenario under warming air temperatures. Variations in the optimized thermal properties resulted in a time difference in thawing depth of 10–15 years and thawing depths varied between 9 and 10 m between the different optimized thermal properties at the end of the 100‐year scenario.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46992854","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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