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}
{"title":"Publisher's Report 2022: Vadose Zone Journal","authors":"","doi":"10.1002/vzj2.20254","DOIUrl":"https://doi.org/10.1002/vzj2.20254","url":null,"abstract":"","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48206633","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}
Martinus Th. (“Rien”) van Genuchten has been awarded the 2023 Wolf Prize in Agriculture. The Wolf Prize is awarded to “outstanding scientists and artists from around the world for achievements in the interest of humanity and friendly relations among people.” The prize is awarded in the disciplines of medicine, agriculture, mathematics, chemistry, and physics. For agricultural sciences, the Wolf Prize is widely considered one of the world’s most prestigious recognitions. Rien van Genuchten was born in 1945 in Vught, The Netherlands. He received his early education at the Agricultural University of Wageningen, The Netherlands, and his PhD at New Mexico State University in the United States. He then spent most of his career at the US Salinity Laboratory in Riverside, CA, before moving to the University of Rio de Janeiro, Brazil, and to Utrecht University, The Netherlands. One of his most influential publications describes a closed-form equation for predicting the hydraulic conductivity of unsaturated soils, known as the van Genuchten equation (van Genuchten, 1980). He was, together with Jirka Simunek, the developer of the widely used HYDRUS software package for simulating the movement of water, heat, and solutes in variably saturated media (Šimůnek et al., 2016). Early in his career, he also published a compendium on analytical solutions of the one-dimensional convection–dispersion equation (van Genuchten & Alves, 1982), a resource widely used to analyse solute transport at the column and field scale.
中国对外Th。(“Rien”)van Genuchten被授予2023年沃尔夫农业奖。沃尔夫奖授予“来自世界各地的杰出科学家和艺术家，以表彰他们为人类利益和人民之间的友好关系做出的成就”。该奖项颁发给医学、农业、数学、化学和物理等学科。在农业科学领域，沃尔夫奖被广泛认为是世界上最负盛名的奖项之一。1945年，Rien van Genuchten出生于荷兰的Vught。他在荷兰瓦赫宁根农业大学接受了早期教育，并在美国新墨西哥州立大学获得了博士学位。之后，他在加州河滨市的美国盐度实验室度过了大部分的职业生涯，之后又去了巴西里约热内卢大学和荷兰乌得勒支大学。他最具影响力的出版物之一描述了一个用于预测非饱和土壤水力导电性的封闭形式方程，称为van Genuchten方程(van Genuchten, 1980)。他与Jirka Simunek一起开发了广泛使用的HYDRUS软件包，用于模拟变饱和介质中水、热量和溶质的运动(Šimůnek et al.， 2016)。在他的职业生涯早期，他还出版了一维对流-色散方程解析解的概要(van Genuchten & Alves, 1982)，这是一种广泛用于分析柱级和场级溶质输运的资源。
{"title":"Wolf prize awarded to Rien van Genuchten","authors":"V. Lakshmi, M. Flury","doi":"10.1002/vzj2.20253","DOIUrl":"https://doi.org/10.1002/vzj2.20253","url":null,"abstract":"Martinus Th. (“Rien”) van Genuchten has been awarded the 2023 Wolf Prize in Agriculture. The Wolf Prize is awarded to “outstanding scientists and artists from around the world for achievements in the interest of humanity and friendly relations among people.” The prize is awarded in the disciplines of medicine, agriculture, mathematics, chemistry, and physics. For agricultural sciences, the Wolf Prize is widely considered one of the world’s most prestigious recognitions. Rien van Genuchten was born in 1945 in Vught, The Netherlands. He received his early education at the Agricultural University of Wageningen, The Netherlands, and his PhD at New Mexico State University in the United States. He then spent most of his career at the US Salinity Laboratory in Riverside, CA, before moving to the University of Rio de Janeiro, Brazil, and to Utrecht University, The Netherlands. One of his most influential publications describes a closed-form equation for predicting the hydraulic conductivity of unsaturated soils, known as the van Genuchten equation (van Genuchten, 1980). He was, together with Jirka Simunek, the developer of the widely used HYDRUS software package for simulating the movement of water, heat, and solutes in variably saturated media (Šimůnek et al., 2016). Early in his career, he also published a compendium on analytical solutions of the one-dimensional convection–dispersion equation (van Genuchten & Alves, 1982), a resource widely used to analyse solute transport at the column and field scale.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45493792","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}
European forests are suffering considerably from the consequences of the droughts of recent years, and the exact reasons and influencing factors for this are still not fully understood. This study was conducted to characterize the changes and dynamics of soil moisture in a mixed forest in northern Bavaria within 1 year. Since electrical resistivity correlates well with soil water content, we used two‐dimensional electrical resistivity tomography (ERT) monitoring and time‐lapse analyses to supplement punctual measurements by sensors and soil analyses to show soil moisture changes throughout a whole year (2020–2021). While the topsoil dries out significantly from summer to autumn down to a depth of about 3 m, a clear increase in soil water content and a decrease in resistivity below 3 m can be observed during winter period. Anomalies in the topsoil (0–1 m) showing lower resistivities than the surrounding substrate could be related to tree positions by additional terrestrial laser scans. A significant relationship could be found between tree crown projection area and resistivity in 1–2 m depth. We found a trend that mean resistivity below pine is lower as below beech. ERT data were also used to estimate the soil water content via Archie's law and the results correlate strongly with the measured values, but the degree of correlation varies depending on the depth level. ERT as a noninvasive method, in combination with additional data, for example, on the vitality status of individual trees, could help to better understand root water uptake and water supply to trees, especially during periods of drought.
{"title":"Monitoring spatiotemporal soil moisture variability in the unsaturated zone of a mixed forest using electrical resistivity tomography","authors":"Julia S. Rieder, C. Kneisel","doi":"10.1002/vzj2.20251","DOIUrl":"https://doi.org/10.1002/vzj2.20251","url":null,"abstract":"European forests are suffering considerably from the consequences of the droughts of recent years, and the exact reasons and influencing factors for this are still not fully understood. This study was conducted to characterize the changes and dynamics of soil moisture in a mixed forest in northern Bavaria within 1 year. Since electrical resistivity correlates well with soil water content, we used two‐dimensional electrical resistivity tomography (ERT) monitoring and time‐lapse analyses to supplement punctual measurements by sensors and soil analyses to show soil moisture changes throughout a whole year (2020–2021). While the topsoil dries out significantly from summer to autumn down to a depth of about 3 m, a clear increase in soil water content and a decrease in resistivity below 3 m can be observed during winter period. Anomalies in the topsoil (0–1 m) showing lower resistivities than the surrounding substrate could be related to tree positions by additional terrestrial laser scans. A significant relationship could be found between tree crown projection area and resistivity in 1–2 m depth. We found a trend that mean resistivity below pine is lower as below beech. ERT data were also used to estimate the soil water content via Archie's law and the results correlate strongly with the measured values, but the degree of correlation varies depending on the depth level. ERT as a noninvasive method, in combination with additional data, for example, on the vitality status of individual trees, could help to better understand root water uptake and water supply to trees, especially during periods of drought.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2023-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45332630","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}
L. Banasiak, L. Weaver, B. Humphries, R. Dann, Martina Blaurock, M. Gosses, L. Pang, M. Close
The movement of bacterial and viral pathogens through soil and vadose zone and subsequently into groundwater is a major public health concern. There are relatively few studies on the transport and fate of microbes through variably saturated vadose zone media compared with their transport in the soil and saturated groundwater zones. In this study, we investigated the transport of Escherichia coli, F‐RNA bacteriophage MS2, and a conservative solute tracer bromide through three intact vadose zone cores, under saturated (discharge rate ∼100 mm h−1) and unsaturated (discharge rate 10 and 0.5 mm h−1) flow conditions. The vadose zone media were sandy gravel overlying a sand lens in core 1, a heterogeneous SG mix in core 2, and SG with an open framework gravel lens through the middle of the core in core 3. The three flow regimes resulted in different transport characteristics through each of the cores. As expected, microbial transport through all cores was higher under saturated conditions, compared with unsaturated conditions. Overall, E. coli removal was consistently greater than that of MS2 phage irrespective of core media or flow conditions. There were relatively minor removals (factors of 1–2.5) of both microbes under saturated conditions, reductions of 2–3 orders of magnitude under the high flow unsaturated conditions, and almost complete removal (4 to >5 orders of magnitude) under the low flow unsaturated conditions. The much greater removal of microbes under unsaturated conditions has significant implications and potential benefits for land management decisions.
细菌和病毒病原体通过土壤和渗透带并随后进入地下水是一个主要的公共卫生问题。相对于微生物在土壤和饱和地下水中的迁移，对微生物在变饱和气膜带介质中的迁移和命运的研究相对较少。在这项研究中，我们研究了大肠杆菌、F‐RNA噬菌体MS2和保守溶质示踪剂溴化物在饱和(放电速率~ 100 mm h−1)和不饱和(放电速率10和0.5 mm h−1)流动条件下通过三个完整的渗透带核心的运输。孔隙带介质为1号岩心上覆砂透镜体的砂砾石，2号岩心上覆非均质砾石混合物，3号岩心中部覆有开放框架砾石透镜体的砾石。这三种流动形式导致了通过每个岩心的不同输运特性。正如预期的那样，在饱和条件下，微生物通过所有岩心的运输比不饱和条件下更高。总的来说，无论核心介质或流动条件如何，大肠杆菌的去除率始终高于MS2噬菌体。两种微生物在饱和条件下的去除率相对较小(1-2.5)，在高流量不饱和条件下的去除率为2-3个数量级，在低流量不饱和条件下几乎完全去除(4 - 50个数量级)。在不饱和条件下微生物的大量去除对土地管理决策具有重要意义和潜在的好处。
{"title":"Microbial and solute transport through intact vadose zone cores of heterogeneous alluvial gravel under variably saturated conditions","authors":"L. Banasiak, L. Weaver, B. Humphries, R. Dann, Martina Blaurock, M. Gosses, L. Pang, M. Close","doi":"10.1002/vzj2.20250","DOIUrl":"https://doi.org/10.1002/vzj2.20250","url":null,"abstract":"The movement of bacterial and viral pathogens through soil and vadose zone and subsequently into groundwater is a major public health concern. There are relatively few studies on the transport and fate of microbes through variably saturated vadose zone media compared with their transport in the soil and saturated groundwater zones. In this study, we investigated the transport of Escherichia coli, F‐RNA bacteriophage MS2, and a conservative solute tracer bromide through three intact vadose zone cores, under saturated (discharge rate ∼100 mm h−1) and unsaturated (discharge rate 10 and 0.5 mm h−1) flow conditions. The vadose zone media were sandy gravel overlying a sand lens in core 1, a heterogeneous SG mix in core 2, and SG with an open framework gravel lens through the middle of the core in core 3. The three flow regimes resulted in different transport characteristics through each of the cores. As expected, microbial transport through all cores was higher under saturated conditions, compared with unsaturated conditions. Overall, E. coli removal was consistently greater than that of MS2 phage irrespective of core media or flow conditions. There were relatively minor removals (factors of 1–2.5) of both microbes under saturated conditions, reductions of 2–3 orders of magnitude under the high flow unsaturated conditions, and almost complete removal (4 to >5 orders of magnitude) under the low flow unsaturated conditions. The much greater removal of microbes under unsaturated conditions has significant implications and potential benefits for land management decisions.","PeriodicalId":23594,"journal":{"name":"Vadose Zone Journal","volume":"22 1","pages":"20 - 3"},"PeriodicalIF":2.8,"publicationDate":"2023-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46245131","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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