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3 pages, 142 KiB

Open AccessEditorial

River Ecological Restoration and Groundwater Artificial Recharge II

by Yuanzheng Zhai and Jin Wu

Water 2024, 16(10), 1328; https://doi.org/10.3390/w16101328 - 7 May 2024

Viewed by 953

Abstract

The depletion of rivers and groundwater caused by climate change and human activity is threatening water security and ecosystems [...] Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

Research

Jump to: Editorial, Review

22 pages, 7279 KiB

Open AccessArticle

Coupling Simulation and Prediction of Sustainable Utilization of Water Resources in an Arid Inland River Basin under Climate Change

by Xiaofan Qi, Wenpeng Li, Yuejun Zheng, Huqun Cui, Weidong Kang, Zhenying Liu and Xinmin Shao

Water 2023, 15(18), 3232; https://doi.org/10.3390/w15183232 - 11 Sep 2023

Viewed by 1182

Abstract

The arid endorheic basin of northwest China is characterized by rich land resources, water shortage, and a fragile ecological environment. The establishment of a credible coupling model of groundwater and surface water based on multi-source observation data is an effective means to study [...] Read more.

The arid endorheic basin of northwest China is characterized by rich land resources, water shortage, and a fragile ecological environment. The establishment of a credible coupling model of groundwater and surface water based on multi-source observation data is an effective means to study the change in basin water cycles and the sustainable utilization of water resources in the past and future. Based on the latest understanding of hydrogeological conditions, hydrology and water resource utilization data in the middle reaches of the Heihe River Basin (HRB), this paper constructs an up-to-date coupling model of surface water and groundwater to study the water balance change of the basin. The water resources data series under historical replay and CMIP5 climate model prediction are constructed to predict future changes in water resources. The study shows that, under the joint influence of natural conditions and human activities, the average annual recharge of groundwater in the study area from 1990 to 2020 is 17.98 × 10⁸ m³/a, the average annual discharge is 18.62 × 10⁸ m³/a, and the difference between recharge and discharge is −0.64 × 10⁸ m³/a. The total groundwater storage is −19.99 × 10⁸ m³, of which the groundwater storage from 1990 to 2001 was −17.52 × 10⁸ m³ and from 2002 to 2020 was −2.47 × 10⁸ m³. Abundant water from 2002 to 2020 in the basin significantly improved the loss of groundwater storage. Under the prediction of historical reappearance and the CMIP5 CNRM-CM5 model RCP4.5 and RCP8.5 pathways, the groundwater level of the Heihe River–Liyuanhe River inclined plain falls first because the HRB has just experienced a wet season and then rises according to future climate change. The groundwater level of the inclined plain east of the Heihe River and Yanchi basin decreases continuously because of the change in water cycle caused by human activities. The erosion accumulation plain is located in the groundwater discharge zone, and the water level is basically stable. Under the conditions of water resource development and utilization, the runoff of Zhengyixia hydrological station cannot meet the requirements of the “97 Water Dividing Plan” of the State Council in most years in the future, and the ecological and production water in the lower reaches of HRB cannot be effectively guaranteed. With the implementation of water-saving irrigation under the RCP4.5 and RCP8.5 scenarios, the runoff of Zhengyixia can meet the “97 Water Diversion Plan”. It is suggested to further improve the level of agricultural water savings in the middle reaches of the HRB and control the reasonable scale of cultivated land in order to reduce water consumption in the middle reaches of the HRB and implement sustainable utilization of water resources in the HRB. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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26 pages, 8544 KiB

Open AccessArticle

Hydro-Geochemical Characteristics of the Shallow Alluvial Aquifer and Its Potential Artificial Recharge to Sustain the Low Flow of the Garonne River

by Nazeer Asmael, Alain Dupuy, Paul McLachlan and Michel Franceschi

Water 2023, 15(16), 2972; https://doi.org/10.3390/w15162972 - 18 Aug 2023

Cited by 1 | Viewed by 1969

Abstract

The complex and interconnected water challenges linked to global climate change and natural and anthropogenic water resources pressure have become major challenges in the 21st century. The Garonne River and its accompanying alluvial aquifers are considered the most important source for agricultural activities [...] Read more.

The complex and interconnected water challenges linked to global climate change and natural and anthropogenic water resources pressure have become major challenges in the 21st century. The Garonne River and its accompanying alluvial aquifers are considered the most important source for agricultural activities in the Garonne Valley, Nouvelle-Aquitaine Region, southwest France. The water is used for irrigation in summer and to reduce frost damage in spring. The alluvial shallow aquifer is recharged by rainfall, lateral inflow from the hillside, and seepage from the riverbed during the flood periods. The aquifer maintains the flow of the river during dry periods. Moreover, the potential recharge of this aquifer is particularly sensitive to annual climatic fluctuations and consequently affects surrounding ecosystems and related socio-economic activities. The increasing impacts of climate change have increased the concern about the availability of these resources. Various adaptation strategies have been considered to mitigate and adapt to the new situation in southwest France. The artificial recharge of the alluvial aquifer is one such regional adaptation strategy to adapt to climate change. The study has two main objectives: to assess the natural and anthropogenic influence on the groundwater chemistry, and to model water infiltration, and understand the aquifer response and, consequently, the effects on river baseflow. The TAG (Technopole Agen-Garonne) project aims to increase the economic wealth of the region while respecting the region’s agricultural traditions. Runoff water from the TAG zone is collected in retention basins and is a potential source to recharge the shallow alluvial aquifer. Sampling campaigns were carried out during the summer of 2019 to collect groundwater samples from several observation wells. Groundwater levels were measured in 132 wells/boreholes to determine the groundwater level fluctuations and create piezometric maps. Piper, spatial distribution, and ionic ratio plots were used to determine the dominant hydrochemical processes and to delineate the hydrochemical facies in the study area. The groundwater chemistry is controlled by silicate weathering and anthropogenic influence. Groundwater quality appears to be affected by the river water in the wells located in the low plain area. The measurements showed that the groundwater levels in the wells located near the river increase more than 2 m after a flood event. The artificial recharge has increased the groundwater level by more than 1 m close to the infiltration basin after a rainstorm. Similarly, a three-dimensional (3D) groundwater model shows a similar magnitude aquifer response to the induced infiltration. The modeling-obtained result shows that the infiltrated water would take about 4 months to reach the Garonne River, which is an appropriate time to maintain the river’s low-flow and thermal buffering capacity, and thus the functioning of its ecosystems during dry periods. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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14 pages, 2060 KiB

Open AccessArticle

Investigating the Change Pattern in Adsorption Properties of Soil Media for Non-Polar Organic Contaminants under the Impact of Freezing and Thawing

by Jingjing Huang, Rong Zhong and Hang Lyu

Water 2023, 15(14), 2515; https://doi.org/10.3390/w15142515 - 9 Jul 2023

Cited by 1 | Viewed by 1650

Abstract

The adsorption of petroleum hydrocarbons by soils in the unsaturated zone determines the amount that goes into the groundwater. However, the intricate behavior of petroleum hydrocarbon adsorption in soil media under the influence of freeze–thaw conditions in globally prevalent seasonally frozen regions remains [...] Read more.

The adsorption of petroleum hydrocarbons by soils in the unsaturated zone determines the amount that goes into the groundwater. However, the intricate behavior of petroleum hydrocarbon adsorption in soil media under the influence of freeze–thaw conditions in globally prevalent seasonally frozen regions remains unclear. Alkanes as a non-polar compound are an important part of petroleum hydrocarbons. We conducted field-scale seasonal freeze-thaw experiments using n-dodecane to quantify the dynamic patterns and influencing factors of the physicochemical properties of soil media and their adsorption capacity for petroleum hydrocarbons during different freeze–thaw cycles. Our findings demonstrated that, as the number of natural freeze–thaw cycles increased, the proportion of soil micro-agglomerates rose rapidly, thereby expanding the available adsorption sites and enhancing the adsorption capacity for non-polar organic pollutants. The rise in sorption capacity for the outdoor freeze–thaw experimental group surpassed that of the indoor room-temperature control group by an impressive 75.57%, showing the enhancement of the adsorption capacity for non-polar organic pollutants. Conversely, the decline in soil organic matter content during the later stages of the freeze–thaw process hampered its adsorption performance for non-polar organic pollutants. The decrease in sorption capacity for the outdoor freeze–thaw experimental group surpassed that of the indoor room temperature control group by 77.97%. By shedding light on the adsorption mechanisms of non-polar organic pollutants in soils subjected to freeze–thaw conditions, our research facilitated a comprehensive understanding and predictive modeling of this process. Furthermore, our study provided a scientific foundation for exploring the convergence and migration transformation patterns of other organic compounds in petroleum-contaminated areas within seasonally frozen regions. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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17 pages, 3743 KiB

Open AccessArticle

Impacts of River Bank Filtration on Groundwater Hydrogeochemistry in the Upper of Hutuo River Alluvial Plain, North China

by Baoyun Zhang, Lining Chen, Yasong Li, Yaci Liu, Chao Li, Xiangke Kong and Yuanjing Zhang

Water 2023, 15(7), 1343; https://doi.org/10.3390/w15071343 - 30 Mar 2023

Cited by 3 | Viewed by 2812

Abstract

River bank filtration (RBF) under human supervision has been applied for groundwater recharge. This study clarified the characteristics of water composition and its origins during the reservoir water recharge RBF. The groundwater samples were collected during four periods: pre-recharge (June 2018), early recharge [...] Read more.

River bank filtration (RBF) under human supervision has been applied for groundwater recharge. This study clarified the characteristics of water composition and its origins during the reservoir water recharge RBF. The groundwater samples were collected during four periods: pre-recharge (June 2018), early recharge (November 2018), intermediate recharge (May 2019), and late recharge (October 2019). Hydrogeochemical methods (Piper diagram, chlor-alkali index, and ion correlation) and principal component analysis (PCA) were used to analyze the chemical evolution of groundwater in the aforementioned periods. TDS concentration tended to increase in the later stage due to the aggravation of carbonate rock dissolution and cation exchange adsorption. Results demonstrated a small, temporary influence of reservoir water on groundwater, characterized as the Ca–Mg–HCO₃–SO₄ and Ca–Mg–SO₄–HCO₃ types, both before and after the recharge. The research on water chemistry changes under different mixing ratios depicts that the continuation of the recharge process promotes mineral dissolution. Rock dissolution was the primary environmental control factor of groundwater components during the recharge period. This strengthened the water–rock reaction and caused potential risk impacts such as the increase of nitrate. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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14 pages, 2983 KiB

Open AccessArticle

Heavy Metals in Sediments of Hulun Lake in Inner Mongolia: Spatial-Temporal Distributions, Contamination Assessment and Source Apportionment

by Tong Liu, Dasheng Zhang, Weifeng Yue, Boxin Wang, Litao Huo, Kuo Liu and Bo-Tao Zhang

Water 2023, 15(7), 1329; https://doi.org/10.3390/w15071329 - 28 Mar 2023

Cited by 3 | Viewed by 2493

Abstract

The spatial and temporal distributions, contamination evaluation, and source apportionment of Cu, Zn, As, Pb, Cd, and Cr in the sediments of Hulun Lake were explored in this work. The pollution characteristics of six heavy metals were assessed by single factor pollution index [...] Read more.

The spatial and temporal distributions, contamination evaluation, and source apportionment of Cu, Zn, As, Pb, Cd, and Cr in the sediments of Hulun Lake were explored in this work. The pollution characteristics of six heavy metals were assessed by single factor pollution index (PI) and geo-accumulation index (Igeo). The sources of heavy metals in the surface sediments were analyzed by the positive definite matrix factorization (PMF) and Pearson correlation analysis. The sedimentary records of heavy metals in core sediments were reproduced by radioisotopes. The average concentrations of 6 heavy metals except Cd were lower than the corresponding background values. The spatial distributions of Cu, Zn, Cr, Cd and As were generally similar and showed higher abundances in the southwestern part of the lake. With the use and import of heavy metals, the concentration of heavy metals in core sediments increased with the fluctuation of years. The peak of heavy metal concentration was related to the high growth rate of gross domestic product in 2003-2008. The single factor pollution index and geo accumulation index results showed that the surface sediment was mainly polluted by Cd, followed by Zn and As. Natural parent material, agricultural activities and industrial activities were the main sources of heavy metal pollution in the sediments, accounting for 17.03%, 26.34%, and 56.63% of the total heavy metal accumulation, respectively. Pb was derived mainly from natural parent material. Cd and As were closely associated with agricultural activities. Cu and Zn were mainly attributed to industrial mining activities. Source apportionment of the ecological risks of heavy metals illustrated that industrial sources were the primary ecosystem risk sources (66.1%), followed by agricultural sources (23.75%) and natural sources (10.15%). The results will also provide reference data for future studies of heavy metals pollution in sediments from Hulun Lake and other lakes. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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16 pages, 2699 KiB

Open AccessArticle

A Multi-Dimensional Comprehensive Assessment (MDCA) Method for the Prioritization of Water Pollution Treatment Technologies in China

by Jiao Li, Yujiao Wen, Jinyuan Jiang, Wei Tan and Tianyi Zhang

Water 2023, 15(4), 751; https://doi.org/10.3390/w15040751 - 14 Feb 2023

Cited by 1 | Viewed by 2299

Abstract

Water pollution treatment technology assessment methods can be used to guide the selection of scientific and reasonable water pollution treatment technologies. At present, China has not yet established a standardized methodological system to scientifically evaluate these technologies, which makes it difficult to effectively [...] Read more.

Water pollution treatment technology assessment methods can be used to guide the selection of scientific and reasonable water pollution treatment technologies. At present, China has not yet established a standardized methodological system to scientifically evaluate these technologies, which makes it difficult to effectively screen water pollution treatment technologies suitable for specific watersheds or regions and restricts the sustainable development of local economy and society. In this study, an MDCA framework for water pollution treatment technologies was developed using a sustainable assessment approach. The framework begins with the definition of water pollution treatment technologies’ decision-making problems and then proceeds through the following: select potential water pollution treatment technologies; identify indicators; decision making; indicator scoring; indicator weighting; select appropriate assessment model; uncertainty analysis; and other steps to ultimately determine preferred options. To demonstrate the validity and applicability of the framework, typical urban wastewater treatment technologies were selected for case validation. The results showed that the comprehensive assessment results obtained by the multidimensional assessment model based on the ideal point method and weighted method were basically consistent. SBR and TAS can be used as recommended technologies for urban sewage treatment in the study area. However, these two technologies also have shortcomings, such as the unsatisfactory economic benefit of SBR, and the high sludge production and poor resistance to hydraulic shock loading of TAS. Among the six alternative technologies, CWS had the worst environmental benefit, mainly due to the low ammonia removal rate. A2/O has the worst economic and technical performance, mainly due to high investment and operation cost, relatively complex operation management, and poor resistance to hydraulic shock load. The method established in this study can not only select the technology, but also identify the shortcomings of the technology, therefore realizing the systematization and standardization. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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21 pages, 9908 KiB

Open AccessArticle

Effect of Ecological Water Supplement on Groundwater Restoration in the Yongding River Based on Multi-Model Linkage

by Tian Nan and Wengeng Cao

Water 2023, 15(2), 374; https://doi.org/10.3390/w15020374 - 16 Jan 2023

Cited by 4 | Viewed by 2678

Abstract

Evaluating the effect of ecological water supplement on groundwater restoration quantitatively could produce positive contributions to both water cycle theory and surface–groundwater conjunctive management. Therefore, in this paper, a groundwater flow numerical model has been established after calculating the river section seepage rate [...] Read more.

Evaluating the effect of ecological water supplement on groundwater restoration quantitatively could produce positive contributions to both water cycle theory and surface–groundwater conjunctive management. Therefore, in this paper, a groundwater flow numerical model has been established after calculating the river section seepage rate using a fuzzy mathematical method in the Yongding River channel. The simulated results show that the model could accurately reflect the real groundwater dynamic features. Then, a data-driven random forest(RF) model has been established to quantitatively evaluate the contributions of the factors which influence the groundwater level variation. The Nash-Sutcliffe efficiency coefficient(NSE) of the RF model is 0.93. It shows excellent ability to identify the rising zone of groundwater level. The study shows that the infiltration capacity is strong in the upstream area of the Yongding River, and the seepage rate is over 0.7. The lowest seepage rate is 0.19 at the downstream end, while the seepage rate in the middle area is basically between 0.4 and 0.7. From 2018 to 2019, the ecological water supplement of the Yongding River has played a significant role in raising the groundwater level along the river channel. Additionally, its contribution analyzed by the RF model to the change of groundwater level is 25%. Groundwater exploitation is the most important variable affecting the groundwater level variation. The impact depth of groundwater level fluctuation reaches about 10 m. The impact range where the groundwater level average uplifts 1.86 m is 502.13 km². The influence direction gradually changes from around the ecological water supplement section to along the Yongding River channel. The groundwater level variation along the tangential direction of the Yongding River is slowing down. The groundwater level would entirely uplift with 170 × 10⁶ m³/year ecological water supplement of the Yongding River and 35.77 × 10⁶ m³/year groundwater mining reduction in the downstream area until 2035. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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12 pages, 2681 KiB

Open AccessArticle

Effects of Ammonium and COD on Fe and Mn Release from RBF Sediment Based on Column Experiment

by Xuelian Xia, Yanguo Teng and Yuanzheng Zhai

Water 2023, 15(1), 120; https://doi.org/10.3390/w15010120 - 29 Dec 2022

Cited by 2 | Viewed by 1805

Abstract

Riverbank filtration (RBF) is an important part of the surface water–groundwater cycle, and it intercepts and retains many pollutants in rivers. However, RBF affects the biogeochemical process which enables aquifer sediments to release iron (Fe) and manganese (Mn). In this study, column experiments [...] Read more.

Riverbank filtration (RBF) is an important part of the surface water–groundwater cycle, and it intercepts and retains many pollutants in rivers. However, RBF affects the biogeochemical process which enables aquifer sediments to release iron (Fe) and manganese (Mn). In this study, column experiments were performed to investigate the effects of ammonium ions and organic matter on Fe and Mn release from anaerobic RBF sediments. In addition, high-throughput sequencing technology was used to characterize the microbial community. The results showed that the ammonium ions (NH₄⁺) and organic matter (COD) in groundwater promote the release of Fe and Mn from aquifer sediments. The trends of Fe and Mn release were similar during the leaching process. The maximum concentrations of Fe and Mn were 0.32 and 40 μg/L, respectively. The structural diversity and abundance of the microbial communities in the groundwater were closely related to the Fe/Mn content. Actinobacteriota, Proteobacteria, Acidobacteriota, Bacteroidota, and Chloroflexi were the dominant phyla, while Rhodococcus, Ochrobactrum, and Pseudarthrobacter were the dominant genera. These functional microbes are actively involved in the biogeochemical cycling of Fe, Mn, and N. In summary, contaminants and the microbial-community structure have dual effects on the release of Fe and Mn from RBF aquifers. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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13 pages, 2203 KiB

Open AccessArticle

Distribution and Ecological Risk Assessment of Pharmaceuticals and Personal Care Products in Sediments of North Canal, China

by Shasha Pei, Binghua Li, Boxin Wang, Jingchao Liu and Xuanying Song

Water 2022, 14(13), 1999; https://doi.org/10.3390/w14131999 - 22 Jun 2022

Cited by 8 | Viewed by 2746

Abstract

The pollution of water bodies by pharmaceuticals and personal care products (PPCPs) has attracted widespread concern due to their widespread use and pseudo-persistence, but their effects on sediments are less known. In this study, solid-phase extraction-high performance liquid chromatography–tandem mass spectrometry (SPE-LC/MSMS) was [...] Read more.

The pollution of water bodies by pharmaceuticals and personal care products (PPCPs) has attracted widespread concern due to their widespread use and pseudo-persistence, but their effects on sediments are less known. In this study, solid-phase extraction-high performance liquid chromatography–tandem mass spectrometry (SPE-LC/MSMS) was used to investigate the occurrence and ecological risks of five typical pharmaceuticals and personal care products (PPCPs) in thirteen key reservoirs, sluices, dams, and estuaries in the Haihe River Basin. At the same time, the PPCP exchanges of surface water, groundwater, and sediments in three typical sections were studied. Finally, the PPCP’s environmental risk is evaluated through the environmental risk quotient. The results showed that the five PPCPs were tri-methoprazine (TMP), sinolamine (SMX), ibuprofen (IBU), triclosan (TCS), and caffeine (CAF). The average concentration of these PPCPs ranged from 0 to 481.19 μg/kg, with relatively high concentrations of TCS and CAF. The relationship between PPCPs in the surface sediments was analyzed to reveal correlations between SMX and TMP, CAF and IBU, CAF and TCS. The risk quotients (RQ) method was used to evaluate the ecological risk of the five detected PPCPs. The major contributors of potential environmental risks were IBU, TCS and CAF, among which all the potential environmental risks at the TCS samples were high risk. This study supplemented the research on the ecological risk of PPCPs in sediments of important reaches of the North Canal to reveal the importance of PPCP control in the North Canal and provided a scientific basis for pollution control and risk prevention of PPCPs. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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17 pages, 4993 KiB

Open AccessArticle

Mining Scheme for Small Rivers near Water Sources—A Case Study of Liuan River in Linquan County, China

by Zhenyu He, Bo Kang, Yuezan Tao and Li Qin

Water 2022, 14(12), 1921; https://doi.org/10.3390/w14121921 - 15 Jun 2022

Viewed by 1858

Abstract

During dry seasons or years, the runoff processes from small rivers influence the safety of riverside groundwater source fields. Water source exploitation has a considerable effect on river runoff. In this study, the riverside source field of the Liuan River in the Linquan [...] Read more.

During dry seasons or years, the runoff processes from small rivers influence the safety of riverside groundwater source fields. Water source exploitation has a considerable effect on river runoff. In this study, the riverside source field of the Liuan River in the Linquan County, Anhui Province, was analyzed. The effect of mining on the ecological flow of the river under river runoff conditions in different typical dry years was quantified. This was undertaken using numerical simulations of the groundwater flow to provide guidance for the establishment of mining schemes for riverside source fields. In 95% of typical dry years, the water supply of small rivers is insufficient. The improved 7Q10 method used to calculate the ecological flow in different dry years revealed that mining water had little effect on the ecological flow. However, during the pumping process, the groundwater level of the water source area decreased greatly. The establishment of riverside source fields can aid in reducing excessive development and use of deep groundwater. The planning, construction, and implementation of the “Divert water from the Yangtze River to the Huaihe River” project can effectively reduce the economic losses that have occurred due to severe drought in the local area. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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17 pages, 4120 KiB

Open AccessFeature PaperArticle

Microbial Community Structure of Arsenic-Bearing Groundwater Environment in the Riverbank Filtration Zone

by Shuai Lu, Yimeng Yang, Hanling Yin, Xiaosi Su, Kaining Yu and Chao Sun

Water 2022, 14(10), 1548; https://doi.org/10.3390/w14101548 - 12 May 2022

Cited by 13 | Viewed by 2570

Abstract

Arsenic (As) contamination of groundwater is a global public health problem. Microorganisms have a great effect on the migration and transformation of arsenic. Studying the effect of microbial community structure and function on arsenic release in the groundwater environment of the riverbank filtration [...] Read more.

Arsenic (As) contamination of groundwater is a global public health problem. Microorganisms have a great effect on the migration and transformation of arsenic. Studying the effect of microbial community structure and function on arsenic release in the groundwater environment of the riverbank filtration zone has important theoretical and practical significance. In this paper, in-situ monitoring technology and molecular biology technology were used to study the microbial community in the process of river water infiltration in the Shenyang Huangjia water source, China. The results showed that the structure, diversity and abundance of the microbial community in groundwater were closely related to the arsenic content. Proteobacteria was the dominant phylum in groundwater of the study area, and Acinetobacter, Pseudomonas, Sulfuritalea, Sphingomonas and Hydrogenophaga etc. were the main dominant bacterial genera. In addition to reducing and oxidizing arsenic, these functional microorganisms also actively participated in the biogeochemical cycle of elements such as iron, manganese, nitrogen and sulfur. There was a significant correlation between dominant bacteria and environmental factors. Fe/Mn had a significant positive correlation with As, which brought potential danger to the water supply in high iron and manganese areas. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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17 pages, 5034 KiB

Open AccessArticle

Groundwater Pollution Model and Diffusion Law in Ordovician Limestone Aquifer Owe to Abandoned Red Mud Tailing Pit

by Yueming Qi, Pei Zhou, Junping Wang, Yipeng Ma, Jiaxing Wu and Chengzhi Su

Water 2022, 14(9), 1472; https://doi.org/10.3390/w14091472 - 4 May 2022

Cited by 6 | Viewed by 2091

Abstract

Red mud is a strong alkaline solid waste pollutant produced in the process of aluminum smelting, which causes great pollution to the regional groundwater environment due to its high content of fluorine and aluminum and high concentration of strong alkali. In this study, [...] Read more.

Red mud is a strong alkaline solid waste pollutant produced in the process of aluminum smelting, which causes great pollution to the regional groundwater environment due to its high content of fluorine and aluminum and high concentration of strong alkali. In this study, fluoride ion was selected as the model contaminant, and a numerical model of the groundwater flow field and solute transport was developed using GMS software to simulate and analyze the migration patterns of fluoride contaminants caused by the red mud pit for the fractured karst geohydrological conditions. The results demonstrated that the groundwater model and flow pattern were mainly controlled by atmospheric precipitation recharge, given flow boundary conditions and leakage of rivers and drains. When the concentration of fluorine pollutants in the red mud yard was 60.0 mg/L, the maximum migration distance of F⁻ in the groundwater of the ordovician limestone aquifer was 473, 1160, 1595 and 1750 m after 1, 5, 10 and 15 years of bottom leakage, and the additional transport distances were 687, 435 and 155 m every 5 years, respectively. The range of F⁻ pollution plume was 0.37 km², 1.15 km², 1.95 km² and 2.14 km², respectively and the range of newly added pollution plume was 0.78 km², 0.80 km² and 0.19 km², respectively, every five years. Both indicated that with the extension of time, the migration and diffusion rate of pollutants slow down, and the diffusion volume increased first and then decreased. The F⁻ pollution plume spread from the red mud pit to the northeast, which was consistent with the flow of groundwater. The high-concentration pollution plume was mainly distributed in the Ordovician limestone fractured aquifer in the northeast. This study revealed the migration law of red mud pollutants, and provided a scientific decision-making basis for the prevention and control of red mud groundwater pollution in the future. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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15 pages, 3266 KiB

Open AccessArticle

Migration Law of LNAPLs in the Groundwater Level Fluctuation Zone Affected by Freezing and Thawing

by Jing Zhou, Minghao Pan, Chuping Chang, Ao Wang, Yongqi Wang and Hang Lyu

Water 2022, 14(8), 1289; https://doi.org/10.3390/w14081289 - 15 Apr 2022

Cited by 4 | Viewed by 2279

Abstract

Freezing and thawing can cause dynamic fluctuations of the groundwater level, resulting in the migration and retention of LNAPLs. However, this process is difficult to observe visually, and a suitable simulation method for its quantitative calculation is lacking. In this study, a numerical [...] Read more.

Freezing and thawing can cause dynamic fluctuations of the groundwater level, resulting in the migration and retention of LNAPLs. However, this process is difficult to observe visually, and a suitable simulation method for its quantitative calculation is lacking. In this study, a numerical simulation is established by coupling the HYDRUS-1D software and the TOUGH program to realize dynamic simulation of the entire process of soil temperature changes, water migration, water level fluctuation, and redistribution of LNAPLs during the freeze–thaw process. The results of the study show that the process of soil freezing and thawing causes water migration, which in turn causes groundwater level fluctuation, leading to the migration and redistribution of LNAPLs within the water level fluctuation zone. In this process, the soil particle size and porosity control the response degree and speed of the water level under freezing and thawing and the spatiotemporal distribution of LNAPLs by affecting the soil temperature, capillary force, and water migration. The migration ability of free LNAPLs is determined by their own density and viscosity; the retention of residual LNAPLs is affected by soil porosity and permeability as well as LNAPL viscosity. The results of this study can not only be used to develop a simulation method for the migration and retention mechanism of LNAPLs in cold regions but also serve as a scientific and theoretical basis for LNAPL pollution control in seasonal frozen soil regions. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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Review

Jump to: Editorial, Research

24 pages, 10670 KiB

Open AccessReview

Geo-Environmental Models of In-Situ Leaching Sandstone-Type Uranium Deposits in North China: A Review and Perspective

by Fuxin Zheng, Yanguo Teng, Yuanzheng Zhai, Jingdan Hu, Junfeng Dou and Rui Zuo

Water 2023, 15(6), 1244; https://doi.org/10.3390/w15061244 - 22 Mar 2023

Cited by 6 | Viewed by 3779

Abstract

Since the 1990s, sandstone-type uranium in the northern basin of China has become the main target for mining. Uranium mining can cause a series of impacts on the environment. A conceptual model of the geo-environment for sandstone-type uranium in northern China was described, [...] Read more.

Since the 1990s, sandstone-type uranium in the northern basin of China has become the main target for mining. Uranium mining can cause a series of impacts on the environment. A conceptual model of the geo-environment for sandstone-type uranium in northern China was described, which covers the changes in the geo-environmental characteristics in the natural state, in the mining process, during decommissioning and after treatment. Sandstone-type uranium is mainly distributed in the Songliao, Erlian, Ordos, Turpan–Hami and Ili Basins, which have arid climates and poor stratum permeability. Pitchblende is the main uranium-bearing mineral and is associated with iron, copper, coal, organic matter and other minerals. The mineral often has a low ore grade (0.01–1.0%) and high carbonate content (2–25%). Uranyl carbonate accounts for more than 90% of the total uranium in groundwater. The uranyl content is closely related to the TDS. The TDS of groundwater in the eastern and central ore belts is usually lower than 2 g/L, while in the western region, such as Xinjiang, it can exceed 10 g/L. In situ leaching (ISL) is the main mining method that results in groundwater pollution. Acid leaching leads to a pH decrease (<3), and heavy metals represented by U and Fe exceed the background values by hundreds of times, resulting in groundwater pollution. CO₂ leaching is more environmentally friendly, and the excess ions are usually Ca²⁺, Mg²⁺, NO₃⁻ and HCO₃⁻. Soil chemical anomalies originate mostly from wind erosion and precipitation leaching of decommissioned tailings. Uranium pollution is mainly concentrated within 20 cm of the surface, and the exceedance generally varies from two to 40 times. During ISL, a series of environmental measures will be taken to prevent pollution from being exposed to the surface. After treatment, the decommissioned uranium mines will likely have no impact on the surrounding environment. In the future, the protection of groundwater should be strengthened during production, and remediation methods based on electrokinetic, microbial and permeable reactive barrier (PRB) technology should be further researched. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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19 pages, 1286 KiB

Open AccessReview

A Review of Advances in Groundwater Evapotranspiration Research

by Xianglong Hou, Hui Yang, Jiansheng Cao, Wenzhao Feng and Yuan Zhang

Water 2023, 15(5), 969; https://doi.org/10.3390/w15050969 - 2 Mar 2023

Cited by 8 | Viewed by 4326

Abstract

Groundwater evapotranspiration (ET_g) is an important component of the hydrological cycle in water-scarce regions and is important for local ecosystems and agricultural irrigation management. However, accurate estimation of ET_g is not easy due to uncertainties in climatic conditions, vegetation parameters, [...] Read more.

Groundwater evapotranspiration (ET_g) is an important component of the hydrological cycle in water-scarce regions and is important for local ecosystems and agricultural irrigation management. However, accurate estimation of ET_g is not easy due to uncertainties in climatic conditions, vegetation parameters, and the hydrological parameters of the unsaturated zone and aquifers. The current methods for calculating ET_g mainly include the WTF method and the numerical groundwater model. The WTF method often requires data supplementation from the numerical unsaturated model to reduce uncertainty; in addition, it relies on point-monitoring data and cannot solve the spatial heterogeneity of ET_g. The ET_g calculation module of the numerical groundwater model is set up too simply and ignores the influence from the unsaturated zone and surface cover. Subsequent research breakthroughs should focus on the improvement of WTF calculation theory and the setting up of an aquifer water-table fluctuation monitoring network. The numerical groundwater model should couple the surface remote sensing data with the unsaturated zone model to improve the accuracy of ET_g calculation. Full article

(This article belongs to the Special Issue River Ecological Restoration and Groundwater Artificial Recharge II)

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