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A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Soil and Water".

Deadline for manuscript submissions: 30 December 2024 | Viewed by 7530

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Dr. Wanjun Jiang

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Guest Editor

1. Tianjin Center, China Geological Survey, Tianjin 300170, China
2. North China Center for Geoscience Innovation, China Geological Survey, Tianjin 300170, China
Interests: hydrogeology; isotope hydrogeochemistry; groundwater circulation and evolution; groundwater environment

Prof. Dr. Yizhi Sheng

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Guest Editor

State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Beijing 100083, China
Interests: microbial biogeochemistry; microbe–mineral interaction; soil and groundwater contamination; microbial ecology; hydrogeochemistry
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Dear Colleagues,

Human activities, particularly in regions experiencing the development of industry and agriculture and the exploitation of mineral resources, pose increasing threats to terrestrial ecosystems and groundwater environments. This situation is critical in areas facing water scarcity, where groundwater serves as the primary source of drinking water. Such concerns center around the type, distribution, source, migration, transformation, and ecological health risks associated with various contaminants in soil–groundwater ecosystems. The concentrations of contaminants in these ecosystems are complex due to long-term water–rock interactions, diverse groundwater recharge patterns, hydrologic-biogeochemical processes, and intensive human exploitation. Notably, the threat extends to both traditional and emerging inorganic and organic pollutants, which find their way into human bodies via bioaccumulation, food chains, and drinking water, thus leading to health risks such as chemical toxicity, radiation exposure, and carcinogenic effects. In the face of escalating environmental challenges and the urgent need for sustainable land management, the assessment of soil quality and resources has never been more crucial. Given the pivotal role that soil and groundwater play in supporting agriculture, maintaining natural landscapes, extracting geothermal resources, and providing potable water, it is imperative that we deepen our understanding of these resources.

In response to these environmental challenges, we have established a Special Issue entitled “Soil and Groundwater Quality and Resources Assessment”. This collection of research articles aims to illuminate the critical processes at play and promote innovative approaches that protect our soil and groundwater ecosystems.

Dr. Wanjun Jiang
Prof. Dr. Yizhi Sheng
Guest Editors

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Keywords

multiple contaminants
source apportionment
migration–transformation
ecological health risks
soil–groundwater system

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Published Papers (11 papers)

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Research

18 pages, 10182 KiB

Open AccessArticle

Study on the Evolution Mechanism of Temporal Variability of Chloride Ions in Typical Districts of Ordos City

by Letian Si, Bing Zhang, Ruiqing Zhou, Ruirui Jiang, Wanggang Dong, Rong Ma and Sihang Liu

Water 2024, 16(20), 2935; https://doi.org/10.3390/w16202935 (registering DOI) - 15 Oct 2024

Viewed by 240

Abstract

The study of the temporal evolution of chloride ions in groundwater is important for identifying whether their sources are due to anthropogenic pollution or natural factors. Groundwater in the northern part of Dalat Banner, Ordos City, has high chloride ion content and exhibits strong temporal variability. To identify the source of chloride ions and reveal their evolution mechanisms, the fast Fourier transform (FFT) was used to determine the trend and cycle of chloride ion evolution, and the groundwater dynamics field combined with multivariate statistical analysis was used to identify the source of chloride ion pollution. Calculations show that the background value of chloride ions in groundwater in the study area is 195.17 mg/L, reaching a maximum of 459 mg/L under the influence of rainfall. The fluctuation of chloride ion concentration is mainly related to the total rainfall in the study area over 165 days, and a single rainfall of more than 15 mm affects the concentration of chloride ions in groundwater. The results of this study show that the background values of chloride ions are mainly influenced by the groundwater dynamical field, and the temporal volatility is mainly influenced by atmospheric rainfall. Full article

(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)

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16 pages, 5515 KiB

Open AccessArticle

Field Demonstration of In Situ Slow-Release Oxygen Chemicals Coupled with Microbial Agents for Injection to Remediate BTEX Contamination

by Shuai Yang, Shucai Zhang, Shici Ma, Sheng Zhao and Zhengwei Liu

Water 2024, 16(19), 2815; https://doi.org/10.3390/w16192815 - 3 Oct 2024

Viewed by 520

Abstract

The global concern for risk control of organic contaminated sites is becoming more and more prominent. Traditional ex situ remediation techniques are costly and damage the site, seriously destroying the soil structure and ecological functions. Therefore, in situ means of combining material injection and microbial remediation have become a potential pathway for the green, economical, and efficient remediation of contaminated sites. In this work, a 200 m² test block was selected for the coupled injection of slow-release oxygen materials and microbial agents, and long-term monitoring of groundwater was carried out. The results showed that the slow-release materials could release oxygen for a period of 90 days, which provided an oxidizing environment for microorganisms to rapidly degrade BTEX. For the pre-adapted indigenous degradation bacterial agent test group, the degradation degree of BTEX was up to 98% after 40 days of injection. The results of the application on the field scale proved the feasibility of reinforcing biostimulation for remediation of underground organic contamination through the coupled injection of slow-release oxygen materials and microbial agents. The results provided theoretical and technical support for the in situ remediation of petroleum hydrocarbon-contaminated sites. Full article

(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)

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19 pages, 4569 KiB

Open AccessArticle

Comprehensive Study on Hydrogeological Conditions and Suitability Evaluation of In Situ Leaching for Sandstone-Hosted Uranium Deposit in Erlian Basin

by Lishan Meng, Hang Ning, Wanjun Jiang, Yizhi Sheng, Wei Wang and Chao Tang

Water 2024, 16(19), 2785; https://doi.org/10.3390/w16192785 - 30 Sep 2024

Viewed by 402

Abstract

As a strategic mineral and energy resource, the enrichment and metallogenic mechanism of sandstone-hosted uranium deposits are highly dependent on hydrogeological conditions. However, the relationship between sandstone uranium mineralization and hydrogeological conditions has not received sufficient attention yet. The pumping test, hydrogeological parameters and hydrochemical characteristics were employed to analyze the change characteristics of hydrogeological conditions and evaluate the suitability of in situ leaching (ISL). The results showed that the study area in the Inner Mongolia Autonomous Region could be divided into two groundwater subsystems, namely Quanzha-Engeriyin and Luhai-Zhendai. The latter with relatively high water richness is confined and a main ore-bearing aquifer, which consists of four orebodies. The well discharge (Q) and hydraulic conductivity (K) of Orebody II ranged from 98.40 to 867.36 m³/d and 0.25 to 5.64 m/d, respectively, indicating the aquifer is suitable for the migration, enrichment and mineralization of uranium due to relatively high permeability and fast flow rate. The water storage of Orebodies III-IV gradually deteriorated from east to west in a stepped pattern. And the highest values of Q and K in Orebodies III-IV decreased from 1200 m³/d to 120 m³/d and 1.75 m/d to 0.035 m/d, respectively, suggesting these were conducive to a reduction in and accumulation of uranium under poor hydrodynamic conditions. Additionally, the study area would be defined as three grades, including favorable, relatively favorable and unfavorable areas of ISL according to a comprehensive evaluation. This study provided a scientific basis for evaluating the possibility of in situ leaching for sandstone-hosted uranium deposit. Full article

(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)

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19 pages, 6463 KiB

Open AccessArticle

Biogeochemical Fe-Redox Cycling in Oligotrophic Deep-Sea Sediment

by Di Zhan, Qingyin Xia, Gaoyuan Li, Xinyu Li, Yang Li, Dafu Hu, Jinglong Hu, Ziqi Zhou and Yizhi Sheng

Water 2024, 16(19), 2740; https://doi.org/10.3390/w16192740 - 26 Sep 2024

Viewed by 437

Abstract

Biogeochemical redox cycling of iron (Fe) essentially governs various geochemical processes in nature. However, the mechanistic underpinnings of Fe-redox cycling in deep-sea sediments remain poorly understood, due to the limited access to the deep-sea environment. Here, abyssal sediment collected from a depth of 5800 m in the Pacific Ocean was characterized for its elemental, mineralogical, and biological properties. The sedimentary environment was determined to be oligotrophic with limited nutrition, yet contained a considerable amount of trace elements. Fe-redox reactions in sediment progressed through an initial lag phase, followed by a fast Fe(II) reduction and an extended period of Fe(III) oxidation before achieving equilibrium after 58 days. The presence of an external H₂ electron donor significantly increased the extent of Fe(III) bio-reduction by 7.73% relative to an amendment-free control under high pressure of 58 MPa. A similar enhancement of 11.20% was observed following lactate amendment under atmospheric pressure. Fe(II) bio-oxidation occurred after 16 days’ anaerobic culturing, coupled with nitrate reduction. During Fe bio-redox reactions, microbial community composition was significantly shaped by the presence/absence of an electron donor, while the hydrostatic pressure levels were the controlling factor. Shewanella spp. emerged as the primary Fe(III)-reducing microorganisms, and were stimulated by supplemented lactate. Marinobacter hydrocarbonoclasticus was the predominant Fe(II)-oxidizing microorganism across all conditions. Our findings illustrate continuous Fe-redox reactions occurring in the deep-sea environment, with coexisting Fe-redox microorganisms determining the oscillation of Fe valence states within the abyssal sediment. Full article

(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)

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20 pages, 12465 KiB

Open AccessArticle

Status, Sources, and Risks of Heavy Metals in Surface Sediments of Baiyangdian Lake and Inflow Rivers, North China

by Hongwei Liu, Yaonan Bai, Yihang Gao, Bo Han, Jinjie Miao, Yanchao Shi and Fengtian Yang

Water 2024, 16(19), 2723; https://doi.org/10.3390/w16192723 - 25 Sep 2024

Viewed by 593

Abstract

Baiyangdian Lake, recognized as the largest freshwater body in northern China, plays a vital role in maintaining the regional eco-environment. Prior studies have pointed out the contamination of sediments with heavy metals, raising concerns about eco-environmental challenges. Therefore, it is imperative to evaluate the current pollution levels and ecological threats related to heavy metals found in the sediments of Baiyangdian Lake as well as in its inflow rivers. In May 2022, surface sediments with a depth of less than 20 cm were analyzed for Cu, Zn, Pb, Cr, Ni, As, Cd, and Hg to determine the pollution status, identify sources of pollution, and evaluate potential ecological risks. A range of evaluation methods used by predecessors such as geo-accumulation index (I_geo), enrichment factor (EF), ecological risk index (RI), sediment quality guidelines (SQGs), positive matrix factorization (PMF), absolute principal component score-multiple linear regression model (APCS-MLR), chemical mass balance (CMB), and UNMIX model were analyzed. After comparison, multi-methods including the geo-accumulation index (Igeo), absolute principal component score-multiple linear regression model (APCS-MLR), ecological risk index (RI), and sediment quality guidelines (SQGs) were utilized this time, leading to a better result. Findings reveal that pollution levels are generally low or non-existent, with only 1.64% of sampling sites showing close to moderate pollution levels for Cu, Pb, and Zn, and 4.92% and 1.64% of sites exhibiting close to moderate and moderate pollution levels for Cd, respectively. The main contributors to heavy metal presence are pinpointed as industrial wastewater discharge, particularly Cu, Zn, Pb, Cd, and Hg. The ecological risks are also relatively low, with 4.92%, 1.64%, and 1.64% of sampling sites demonstrating close to moderate, moderate, and strong risks in the inflow rivers, respectively. Additionally, only one site shows moderate potential biological toxicity, while the rest display non-toxicity. These findings will update our cognition and offer a scientific basis for pollution treatment and ecosystem enhancement for government management. Full article

(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)

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17 pages, 13310 KiB

Open AccessArticle

Spatiotemporal Dynamics and Drivers of Coastal Wetlands in Tianjin–Hebei over the Past 80 Years

by Feicui Wang, Fu Wang, Ke Zhu, Peng Yang, Tiejun Wang, Yunzhuang Hu and Lijuan Ye

Water 2024, 16(18), 2612; https://doi.org/10.3390/w16182612 - 14 Sep 2024

Viewed by 577

Abstract

Coastal wetland ecosystems are critical due to their diverse ecological and economic benefits, yet they have been significantly affected by human activities over the past century. Understanding the spatiotemporal changes and underlying factors influencing these ecosystems is crucial for developing effective ecological protection and restoration strategies. This study examines the Tianjin–Hebei coastal wetlands using topographic maps from the 1940s and Landsat satellite imagery from 1975, 2000, and 2020, supplemented by historical literature and field surveys. The aim is to analyze the distribution and classification of coastal wetlands across various temporal intervals. The findings indicate an expansion of the Tianjin–Hebei coastal wetlands from 7301.34 km² in the 1940s to 8041.73 km² in 2020. However, natural wetlands have declined by approximately 44.36 km²/year, while constructed wetlands have increased by around 53.61 km²/year. The wetlands have also become increasingly fragmented, with higher numbers of patches and densities. The analysis of driving factors points to human activities—such as urban construction, cultivated land reclamation, sea aquaculture, and land reclamation—as the primary contributors to these changes. Furthermore, the study addresses the ecological and environmental issues stemming from wetland changes and proposes strategies for wetland conservation. This research aims to enhance the understanding among researchers and policymakers of the dynamics and drivers of coastal wetland changes, as well as the major challenges in their protection, and to serve as a foundation for developing evidence-based conservation and restoration strategies. Full article

(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)

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17 pages, 17982 KiB

Open AccessArticle

Comprehending Spatial Distribution and Controlling Mechanisms of Groundwater in Topical Coastal Aquifers of Southern China Based on Hydrochemical Evaluations

by Jun He, Pan Wu, Yiyong Li, Min Zeng, Chen Chen, Hamza Jakada and Xinwen Zhao

Water 2024, 16(17), 2502; https://doi.org/10.3390/w16172502 - 3 Sep 2024

Viewed by 451

Abstract

Groundwater quality and availability in coastal aquifers have become a serious concern in recent times due to increased abstraction for domestic, agricultural and industrial purposes. (1) Background: Zhuhai city is selected as a representative coastal aquifer in Southern China to comprehensively evaluate the hydrochemical characteristics, spatial distribution and controlling mechanisms of groundwater. (2) Methods: A detailed study utilizing statistical analyses, a Piper diagram, Gibbs plots, and ion ratios was conducted on 114 surface water samples and 211 groundwater samples. (3) Results: The findings indicate that the pH of most groundwater is from 6.06 to 6.52, indicating a weakly acidic environment. The pH of surface water ranges from 5.35 to 9.86, with most values being weakly alkaline. The acidity in the groundwater may be related to the acidic atmospheric precipitation, an acidic unsaturated zone, oxidation of sulphide minerals and tidal action. The groundwater chemical types are predominantly mixed, followed by Ca-Mg-HCO₃ type. Surface water samples are predominantly Na-Cl-SO₄ type. The NO₃⁻ concentration in groundwater is relatively high, with a mean value of 17.46 mg/L. The NO₂⁻ and NH₄⁺ concentrations in groundwater are relatively low, with mean values of 0.46 mg/L and 7.58 mg/L. (4) Conclusions: The spatial distribution of the principal chemical constituents in the groundwater is related to the landform. The chemical characteristics of groundwater in the study area are mainly controlled by the weathering and dissolution of silicate and sulfate minerals, evaporation, seawater mixing and cation exchange. Nitrate in clastic fissure groundwater, granite fissure groundwater and unconfined pore groundwater primarily originates from atmospheric precipitation, agricultural activities of slope farmland and forest land. Nitrate in confined pore groundwater and karst groundwater primarily originates from domestic sewage and mariculture wastewater. Our findings elucidate the processes characterizing the hydrogeology and surface water interactions in Zhuhai City’s coastal system, which are relevant to other catchments with similar geological characteristics. Full article

(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)

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21 pages, 11114 KiB

Open AccessArticle

Hydrogeochemical Characteristics and Health Risk Assessment of Groundwater in Grassland Watersheds of Cold and Arid Regions in Xilinhot, China

by Yubo Xia, Guangfang Chen, Futian Liu, Jing Zhang and Hang Ning

Water 2024, 16(17), 2488; https://doi.org/10.3390/w16172488 - 2 Sep 2024

Viewed by 763

Abstract

Xilinhot City is a significant pastoral city in China where groundwater serves as the primary water source for the cold and arid pastoral regions. The formation and evolution of material components in groundwater, as well as groundwater quality, are directly linked to the health of pastoral residents. This study is based on the physical and chemical test results of 22 groundwater samples collected from the Xilinhot River Basin in Inner Mongolia. Various statistical analyses, including Piper and Chadha diagrams, as well as hydrogeochemical simulation methods, were employed to assess the hydrogeochemical characteristics and material composition sources of groundwater, evaluate groundwater quality and non-carcinogenic risks, and comprehensively discuss the impact of macro- and microelements on human health. The findings indicate that igneous rocks containing minerals such as potassium feldspar, plagioclase, and pyroxene contribute Na⁺, Cl⁻, and K⁺ to the groundwater, while sedimentary rocks containing minerals like dolomite and calcite supply ions such as Ca²⁺, Mg²⁺, and HCO₃⁻. The groundwater quality is primarily classified as Class II–V, with F⁻ and NO₃⁻ exhibiting varying hazard quotients for children and adults in the study area, though they do not pose a non-carcinogenic risk. Additionally, the enrichment of hardness, Ca²⁺, Mg²⁺, Na⁺, SO₄²⁻, and other indicators in localized areas exceeds the recommended values for drinking water, potentially impacting the digestive and urinary systems of the human body. There is a risk of excessive fluoride in areas where F levels exceed 1 mg/L. Furthermore, the content of beneficial micronutrients such as selenium (Se), zinc (Zn), boron (B), and germanium (Ge) is relatively low. Based on the elemental abundance characteristics and a comparative analysis of the chemical properties of groundwater across five regions of China, this comparison facilitates a discussion on the definition of healthy groundwater, particularly in relation to safe consumption in cold and arid regions. This study aims to highlight the health issues associated with drinking groundwater in the cold and arid regions of Mongolia. The findings serve as a valuable reference for efforts aimed at reducing the incidence of endemic diseases and enhancing human lifespan. Full article

(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)

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16 pages, 3123 KiB

Open AccessArticle

Feasibility Research on Surface Water Reinjection into the Sandstone Geothermal Reservoir of the Guantao Formation in Tianjin Based on Laboratory Experiments

by Bing Wang, Yanting Zhao, Yun Cai, Sen Zhang, Baomei Yang and Fei Liu

Water 2024, 16(17), 2475; https://doi.org/10.3390/w16172475 - 30 Aug 2024

Viewed by 482

Abstract

Tianjin possesses abundant geothermal resources, and geothermal reinjection is an effective strategy for maintaining the sustainable development and utilization of these resources. However, several issues have arisen in the reinjection of sandstone geothermal reservoirs in the Tianjin area, including a mismatch between the reinjection capacity and effluent capacity, as well as challenges related to continuous reinjection. Therefore, it is crucial to investigate the reinjection of exogenous water into sandstone pore-type geothermal reservoirs. This study focuses on the geothermal reservoir of the Guantao Formation in the Binhai New Area. The surface water treatment process for reinjection into sandstone geothermal reservoirs was determined through water treatment simulation experiments. Additionally, experiments examining the interaction between the reinjected water and reservoir rock were conducted to assess the feasibility of using treated surface water for reinjection into sandstone geothermal reservoirs. The hydrogeochemical response mechanisms and the impact on the reservoir under reinjection conditions were also investigated. The results indicate that a nanofiltration module and tubular microfiltration membrane are essential to ensure the stability of the system. The pH and TDS of water samples decreased after reinjecting mixed water (HHS) into the sandstone reservoir. The hydrochemical type consistently remained Cl-Na. The conventional water chemistry components and trace elements were influenced by the corresponding water–rock reactions. The reservoir minerals exhibited minimal precipitation, primarily consisting of K-feldspar and Fe-dolomite. The minerals produced during the experiment accounted for only 0.08% of the total cuttings’ mass, indicating a negligible impact on the reservoir structure. PHREEQC was employed to simulate the changes in mineral saturation index before and after the reinjection of mixed water and geothermal water, respectively. Notably, similar hydrogeochemical changes were observed in the geothermal fluids. Thus, this study demonstrates the feasibility of reinjecting treated surface water into sandstone geothermal reservoirs from a hydrogeochemical perspective. This research provides valuable insights for the development of external water reinjection projects in hot spring health care units, contributing effectively to the achievement of carbon peaking and carbon neutrality goals. Full article

(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)

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17 pages, 7508 KiB

Open AccessArticle

A Risk Assessment of the Vegetation Ecological Degradation in Hunshandake Sandy Land, China: A Case Study of Dabusennur Watershed

by Peng Chen, Rong Ma, Letian Si, Lefan Zhao, Ruirui Jiang and Wanggang Dong

Water 2024, 16(16), 2258; https://doi.org/10.3390/w16162258 - 10 Aug 2024

Viewed by 987

Abstract

In the context of climate change, it is essential for sustainable development to assess the risks associated with climate change and human-induced vegetation degradation. The Hunshandake Sandy Land provides a variety of ecosystem services and is a substantial ecological security barrier in the Beijing–Tianjin–Hebei area of China. This study used the Normalized Difference Vegetation Index (NDVI) to analyze the spatiotemporal variation trend in vegetation in the Dabusennur Watershed using linear trend analysis and the GeoDetector model to identify the main drivers of vegetation change in the watershed. Finally, the study assessed the risk of ecological degradation in the vegetation of the watershed. The results show that the NDVI in the study area has had a fluctuating trend in the last 22 years, and the change has been small. Precipitation and groundwater depth are the key factors affecting vegetation change. The NDVI reaches its maximum value when the groundwater depth is at 2.75 m. The vegetation ecology of the basin is relatively fragile, mainly with medium risk and large risk. To cope with the ecological risk of vegetation degradation caused by climate change, appropriate water use strategies should be formulated to ensure ecological water use. The present study’s outcomes provide the basis for developing ecological engineering solutions in the arid and semi-arid parts of northern China. Full article

(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)

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20 pages, 11380 KiB

Open AccessArticle

Changing Soil Water Content: Main Trigger of the Multi-Phase Mobilization and Transformation of Petroleum Pollution Components—Insights from the Batch Experiments

by Mingxing Yang, Bing Wang, Yubo Xia, Yan Qiu, Chunling Li and Zhendong Cao

Water 2024, 16(13), 1775; https://doi.org/10.3390/w16131775 - 22 Jun 2024

Viewed by 951

Abstract

Soil moisture content continuously alters the types and forms of petroleum organic pollutants in the soil through processes such as dissolution, convection, and dilution, forming complex migration and transformation in a water–air–soil–NAPL system. Field investigations and traditional indoor simulation experiments have difficulty in terms of accurately diagnosing the state of different petroleum pollutants due to the influence of environmental factors and the difficulty of controlling single factors. Batch experiments were conducted to simulate the mobilization and differentiation processes of petroleum pollutants under the influence of soil water content. The results show that (1) the residual content of components is the lowest in coarse sand and the highest in clay, which is mainly affected by soil particles; meanwhile, the residual saturation value of octanoic acid is the largest, and that of toluene is the smallest, as determined in terms of their viscosity and volatility. (2) The infiltration processes of the components are affected by their properties and medium characteristics. Due to its small particle size and strong adsorption, clay has the highest residual saturation of petroleum pollutants (28.8%). This can even be more than twice that of coarse sand (13.3%). For different components, the residual saturations of octanoic acid and toluene are the highest and lowest, respectively (taking fine sand as an example: 25.3% and 13.2%), with a relatively large difference, as determined in terms of viscosity and solubility. (3) As the free phase can migrate freely, it is transformed most rapidly in the pores. The changes in the dissolved phase of each component are relatively small and tend to be gentle. The changes in the residual phase are mainly affected by volatility, viscosity, soil particles, and pore and cosmid content; the degree of change is ordered as follows: toluene > cyclohexane > hexadecane > octanoic acid. Full article

(This article belongs to the Special Issue Soil and Groundwater Quality and Resources Assessment)

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