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Advances in Remediation of Contaminated Sites: Volume II
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Advances in Remediation of Contaminated Sites: Volume II

A special issue of Processes (ISSN 2227-9717). This special issue belongs to the section "Environmental and Green Processes".

Deadline for manuscript submissions: 31 July 2024 | Viewed by 25298

Special Issue Editors

Prof. Dr. Guining Lu

E-Mail Website
Guest Editor
School of Environment and Energy, South China University of Technology, Guangzhou 510006, China
Interests: pollution control; soil remediation; e-waste; mining area; heavy hetals; persistent organic pollutants; polybrominated diphenyl ethers
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Zenghui Diao

E-Mail Website
Guest Editor
College of Resources and Environment, Zhongkai University of Agriculture and Engineering, Guangzhou 510225, China
Interests: soil remediation; photoelectrochemical catalysis; catalytic degradation; acid mine drainage; biochar; heavy metals
Prof. Dr. Yaoyu Zhou

E-Mail Website
Guest Editor
College of Resources and Environment, Hunan Agricultural University, Changsha 410128, China
Interests: decontamination of aqueous effluents and waste management; ionizing radiation in environmental application; fundamental soil science and remediation of various contaminants in soils
Special Issues, Collections and Topics in MDPI journals
Dr. Kaibo Huang

E-Mail Website
Guest Editor
School of Ecology and Environment, Hainan University, Haikou 570228, China
Interests: soil washing; photo-transformation; surfactant; e-waste; polychlorinated biphenyls; bi-metal; emerging contaminants
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

With the development of social economy, the population has increased sharply, and the land area involved in people's production and lives has also gradually increased. To meet the production and development needs of society, land resources have been damaged and polluted synchronously due to human activity. Indeed, most site contaminations result from past and present human activities. As land resources are non-renewable, the development of efficient land restoration and improvement approaches is an important approach for achieving the sustainable development of human society.

The remediation of contaminated sites has been one of the most rapidly developing environmental research subjects. The process of the remediation of contaminated sites is a site-specific phased approach comprising site characterization, risk assessment and remediation technology selection and application. Site remediation technology has developed rapidly in recent years, and has brought hope for environmental remediation. However, site remediation technology has also encountered bottlenecks, and new breakthroughs are urgently required.

With the success of the previous Special Issue, “Advances in Remediation of Contaminated Sites: Volume I” (see details in website: www.mdpi.com/si/92730), we decided to organize a second Special Issue on this subject: “Advances in Remediation of Contaminated Sites: Volume II”, which aims to collect the latest progress in the remediation of contaminated sites, in order to help in solving the bottleneck in the development of site remediation technology. We invite researchers to contribute original research papers, review articles, and communications on related subjects to this Special Issue. Topics of interest include but are not limited to:

  • Survey and assessment of contaminated sites;
  • Environmental processes and effects of pollutants;
  • Remediation technology and its application in contaminated sites;
  • Remediation strategy and management in contaminated sites.

We look forward to receiving your contributions.

Prof. Dr. Guining Lu
Prof. Dr. Zenghui Diao
Prof. Dr. Yaoyu Zhou
Dr. Kaibo Huang
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Processes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • site contamination
  • survey and assessment
  • remediation technology
  • remediation strategy
  • site management
  • heavy metals
  • organic pollutants
  • emerging contaminants
  • soils and groundwater
  • water and sediments
  • environmental processes
  • environmental behaviors
  • environmental effects
  • environmental engineering

Published Papers (11 papers)

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16 pages, 8910 KiB  
Article
Assessing Phytoremediation Potential: Dominant Plants in Soils Impacted by Polymetal(loid)lic Mining
by Boxin Wang, Juan Hou, Xueyong Wu, Xuekui Niu and Fengping Zhou
Processes 2024, 12(4), 833; https://doi.org/10.3390/pr12040833 - 19 Apr 2024
Abstract
Phytoremediation, an ecological approach aimed at addressing polymetal(loid)lic-contaminated mining soils, has encountered adaptability challenges. Dominant plant species, well-suited to the local conditions, have emerged as promising candidates for this purpose. This study focused on assessing the phytoremediation potential of ten plant species that [...] Read more.
Phytoremediation, an ecological approach aimed at addressing polymetal(loid)lic-contaminated mining soils, has encountered adaptability challenges. Dominant plant species, well-suited to the local conditions, have emerged as promising candidates for this purpose. This study focused on assessing the phytoremediation potential of ten plant species that thrived in heavy metal(loid)-contaminated mining soils. This investigation covered nine heavy metal(loid)s (As, Cu, Cd, Cr, Hg, Ni, Pb, Sn, and Zn) in both plants and rhizosphere soils. The results revealed a significant impact of mining activities, with heavy metal(loid) concentrations surpassing the Yunnan Province’s background levels by 1.06 to 362 times, highlighting a significant concern for remediation. The average levels of the heavy metal(loid)s followed the order of As (3.98 × 103 mg kg−1) > Cu (2.83 × 103 mg kg−1) > Zn (815 mg kg−1) > Sn (176 mg kg−1) > Pb (169 mg kg−1) > Cr (68.1 mg kg−1) > Ni (36.2 mg kg−1) > Cd (0.120 mg kg−1) > Hg (0.0390 mg kg−1). The bioconcentration factors (BCFs), bioaccumulation factors (BAFs), and translocation factors (TFs) varied among the native plants, indicating diverse adaptation strategies. Low BCFs and BAFs (ranging from 0.0183 to 0.418 and 0.0114 to 0.556, respectively) suggested a low bioavailability of heavy metal(loid)s. Among the species, both J. effusus and P. capitata showed remarkable abilities for As accumulation, while A. adenophora demonstrated a notable accumulation ability for various heavy metal(loid)s, especially Cd, with relatively high BCFs (1.88) and BAFs (3.11), and the TF at 1.66 further underscored the crucial role of translocation in preventing root toxicity. These findings emphasized the potential of these plant species in mine ecological restoration and phytoremediation, guiding targeted environmental rehabilitation strategies. Full article
(This article belongs to the Special Issue Advances in Remediation of Contaminated Sites: Volume II)
16 pages, 2018 KiB  
Article
Adsorption of Zinc(II) Ion by Spent and Raw Agaricus bisporus in Aqueous Solution
by Xiaoyu Zhang, Caiyi Zhao, Feng Xue, Beicheng Xia, Yuanyuan Lu, Rongrong Ying and Zhewei Hu
Processes 2024, 12(4), 717; https://doi.org/10.3390/pr12040717 - 01 Apr 2024
Viewed by 567
Abstract
A significant environmental concern globally is the pollution of water bodies as a result of heavy metals. To date, various attempts have been made to effectively remove heavy metals, such as those that use synthetic and biogenic materials to abate and control water [...] Read more.
A significant environmental concern globally is the pollution of water bodies as a result of heavy metals. To date, various attempts have been made to effectively remove heavy metals, such as those that use synthetic and biogenic materials to abate and control water pollution. The biological removal of pollutants from water is an efficient and environmentally friendly technique. In this study, we evaluated the biosorption characteristics of Zn2+ ions from aqueous solution by spent composed of raw Agaricus biosporium (RAB) and A. biosporium (SCAB). We added different biosorption doses, metal ions, and initial concentrations of pollutants to explore the adsorption of Zn2+ by RAB and SCAB. We applied pseudo-first- and second-order models to investigate the biosorption kinetics. According to our results, the rate of Zn2+ removal from the aqueous solution using raw biomass was significantly lower than that using sodium citrate-treated biomass of SCAB. When the Zn2+ concentration increased from 10 mg L−1 to 200 mg L−1, the rate of removal of RAB decreased from 73.9% to 38.4%, and that of Zn2+ by SCAB decreased from 99.9% to 75.9%. As we increased the biosorbent dose, the rate of Zn2+ removal by SCAB increased. Interestingly, Zn2 biosorption was inhibited by heavy co ions (Cu2+ and Pb2+) and light metals (e.g., Na+, Mg2+, K+, and Ca2+). When treating wastewater polluted with Zn2+, Pb2+, and Cu2+, SCAB showed good potential. The results of this study provide a scientific basis for an environmentally sound approach to controlling water pollution. Full article
(This article belongs to the Special Issue Advances in Remediation of Contaminated Sites: Volume II)
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20 pages, 6483 KiB  
Article
Comparing the Aging Processes of PLA and PE: The Impact of UV Irradiation and Water
by Xucheng Wang, Jinxin Chen, Wenhao Jia, Kaibo Huang and Yini Ma
Processes 2024, 12(4), 635; https://doi.org/10.3390/pr12040635 - 22 Mar 2024
Viewed by 486
Abstract
The aging processes of microplastics (MPs) are prevalent in natural environments. Understanding the aging mechanisms of MPs is crucial for assessing their environmental behavior and potential risks. In this study, we selected polylactic acid (PLA) and polyethylene (PE) as representatives of biodegradable and [...] Read more.
The aging processes of microplastics (MPs) are prevalent in natural environments. Understanding the aging mechanisms of MPs is crucial for assessing their environmental behavior and potential risks. In this study, we selected polylactic acid (PLA) and polyethylene (PE) as representatives of biodegradable and conventional plastics, respectively, to examine changes in their physicochemical properties induced by water and UV light exposure. Laboratory aging resulted in significant fragmentation, characterized by cracks and pores on the surfaces, for both types of MPs, with PLA MPs exhibiting more severe changes, particularly under combined UV and water exposure. Notably, PLA MPs tended to become progressively smaller after aging, whereas PE MPs did not show significant size changes. Chemical analyses of aged MPs using micro-Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) revealed a substantial increase in the carbonyl index (CI) and oxygen content for PE, suggesting surface oxidation during photo-oxidation. Conversely, PLA MPs displayed a CI decrease, along with an oxygen content increase, indicating the breakdown of ester linkages in PLA and the formation of other oxidation products. Furthermore, we developed and optimized pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) methods to identify potential chemical degradation products of PE and PLA, considering their differing thermal stabilities. We observed a distinct trend regarding the peaks in the chromatogram of aged MPs and identified the typical oxidation and crosslinking products for PLA. Additionally, after the aging process, both PE and PLA exhibited a significant increase in organic carbon content, with the eluate containing submicron/nano-sized particles. This study provides a scientific foundation for a deeper understanding of the environmental aging mechanisms of various MPs, particularly in regards to the effects of UV irradiation and water exposure. Full article
(This article belongs to the Special Issue Advances in Remediation of Contaminated Sites: Volume II)
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14 pages, 2135 KiB  
Article
Utilizing Machine Learning Models with Molecular Fingerprints and Chemical Structures to Predict the Sulfate Radical Rate Constants of Water Contaminants
by Ting Tang, Dehao Song, Jinfan Chen, Zhenguo Chen, Yufan Du, Zhi Dang and Guining Lu
Processes 2024, 12(2), 384; https://doi.org/10.3390/pr12020384 - 14 Feb 2024
Viewed by 750
Abstract
Sulfate radicals are increasingly recognized for their potent oxidative capabilities, making them highly effective in degrading persistent organic pollutants (POPs) in aqueous environments. These radicals excel in breaking down complex organic molecules that are resistant to traditional treatment methods, addressing the challenges posed [...] Read more.
Sulfate radicals are increasingly recognized for their potent oxidative capabilities, making them highly effective in degrading persistent organic pollutants (POPs) in aqueous environments. These radicals excel in breaking down complex organic molecules that are resistant to traditional treatment methods, addressing the challenges posed by POPs known for their persistence, bioaccumulation, and potential health impacts. The complexity of predicting interactions between sulfate radicals and diverse organic contaminants is a notable challenge in advancing water treatment technologies. This study bridges this gap by employing a range of machine learning (ML) models, including random forest (DF), decision tree (DT), support vector machine (SVM), XGBoost (XGB), gradient boosting (GB), and Bayesian ridge regression (BR) models. Predicting performances were evaluated using R2, RMSE, and MAE, with the residual plots presented. Performances varied in their ability to manage complex relationships and large datasets. The SVM model demonstrated the best predictive performance when utilizing the Morgan fingerprint as descriptors, achieving the highest R2 and the lowest MAE value in the test set. The GB model displayed optimal performance when chemical descriptors were utilized as features. Boosting models generally exhibited superior performances when compared to single models. The most important ten features were presented via SHAP analysis. By analyzing the performance of these models, this research not only enhances our understanding of chemical reactions involving sulfate radicals, but also showcases the potential of machine learning in environmental chemistry, combining the strengths of ML with chemical kinetics in order to address the challenges of water treatment and contaminant analysis. Full article
(This article belongs to the Special Issue Advances in Remediation of Contaminated Sites: Volume II)
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17 pages, 5508 KiB  
Article
Quantitative Analysis of Soil Cd Content Based on the Fusion of Vis-NIR and XRF Spectral Data in the Impacted Area of a Metallurgical Slag Site in Gejiu, Yunnan
by Zhenlong Zhang, Zhe Wang, Ying Luo, Jiaqian Zhang, Xiyang Feng, Qiuping Zeng, Duan Tian, Chao Li, Yongde Zhang, Yuping Wang, Shu Chen and Li Chen
Processes 2023, 11(9), 2714; https://doi.org/10.3390/pr11092714 - 11 Sep 2023
Viewed by 679
Abstract
Vis-NIR and XRF spectroscopy are widely used in monitoring heavy metals in soil due to their advantages of being fast, non-destructive, cost-effective, and non-polluting. However, when used individually, XRF and vis-NIR may not meet the accuracy requirements for Cd determination. In this study, [...] Read more.
Vis-NIR and XRF spectroscopy are widely used in monitoring heavy metals in soil due to their advantages of being fast, non-destructive, cost-effective, and non-polluting. However, when used individually, XRF and vis-NIR may not meet the accuracy requirements for Cd determination. In this study, we focused on the impact area of a non-ferrous metal smelting slag site in Gejiu City, Yunnan Province, fused the pre-selected vis-NIR and XRF spectra using the Pearson correlation coefficient (PCC), and identified the characteristic spectra using the competitive adaptive reweighted sampling (CARS) method. Based on this, a quantitative model for soil Cd concentration was established using partial least squares regression (PLSR). The results showed that among the four fusion spectral quantitative models constructed, the model combining vis-NIR spectral second-order derivative transformation and XRF spectral first-order derivative transformation (D2(vis-NIR) + D1(XRF)) had the highest coefficient of determination (R2 = 0.9505) and the smallest root mean square error (RMSE = 0.1174). Compared to the estimation models built using vis-NIR and XRF spectra alone, the average computational time of the fusion models was reduced by 68.19% and 63.92%, respectively. This study provides important technical means for real-time and large-scale on-site rapid estimation of Cd content using multi-source spectral fusion. Full article
(This article belongs to the Special Issue Advances in Remediation of Contaminated Sites: Volume II)
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16 pages, 3671 KiB  
Article
Effects of Lead Pollution on Photosynthetic Characteristics and Chlorophyll Fluorescence Parameters of Different Populations of Miscanthus floridulus
by Jianqiao Qin, Xueding Jiang, Jianhua Qin, Huarong Zhao, Min Dai, Hao Liu and Xi Chen
Processes 2023, 11(5), 1562; https://doi.org/10.3390/pr11051562 - 19 May 2023
Cited by 1 | Viewed by 1304
Abstract
This study was conducted in order to study the effect of different concentrations of lead pollution on the photosynthetic characteristics and growth of Miscanthus floridulus, and to reveal its photosynthetic adaptability to lead stress. The differences of gas exchange parameters, chlorophyll fluorescence [...] Read more.
This study was conducted in order to study the effect of different concentrations of lead pollution on the photosynthetic characteristics and growth of Miscanthus floridulus, and to reveal its photosynthetic adaptability to lead stress. The differences of gas exchange parameters, chlorophyll fluorescence characteristics and photosynthetic pigment of two Miscanthus floridulus populations, one population from Boluo an uncontaminated site, and another population from Dabaoshan, a mine site, were compared and studied through nutrient solution culture experiments treated with heavy metal lead (Pb) in green house. The results showed that (1) under Pb stress, the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), intercellular carbon dioxide concentration (Ci), and chlorophyll content (Chl) of the leaves of the two populations decreased in different amplitude. Under moderate and severe Pb stress (80 mg·L−1, 120 mg·L−1, 240 mg·L−1), the plant biomass of non-mining population and mining population plants were 54.5%, 39.7%, 29.4% and 70.4%, 54.7%, 50.9% of the control, respectively. (2) Stomatal restriction was the main factor for the Pn’s decrease in the leaves of the non-mine population under light Pb stress, while the non-stomatal restriction was the main factor for Pn’s decrease in the leaves of the non-mine population under middle and high Pb stresses. (3) Under Pb stress, the maximum photochemical efficiency (Fv/Fm) and potential activity (Fv/Fo) of PS II reaction centers in the two populations of M. floridulus decreased. However, Fv/Fm and Fv/Fo showed a smaller decrease, but the capability to utilize light and the potential to activate PSII of the mine population remained higher than that of the non-mine population. The changes of photochemical quenching coefficient (qP) and non-photochemical quenching coefficient (NPQ) of PSⅡ showed that qP value decreased and NPQ value increased in the two populations under Pb stress. On the whole, the resistance mining area population had a low qP reduction and a large increase in NPQ. Electronic transfer rate (ETR) and PSII actual fluorescence efficiency (ΦPSII) of the mine population changed slightly under Pb stress. These results indicated that when under Pb stress, the electron transport activity and photosynthetic apparatus were damaged less in the mine population with high resistance than in the non-mine population with low resistance. Conclusion: the mining population of M. floridulus has strong tolerance to Pb, which is suitable for the pioneer species of gramineae in vegetation restoration construction in metal mining area. Full article
(This article belongs to the Special Issue Advances in Remediation of Contaminated Sites: Volume II)
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12 pages, 2693 KiB  
Article
Performance and Bacteria Communities of a Full-Scale Constructed Wetland Treating the Secondary Effluent after Multi-Years’ Operation
by Siyuan Song, Baogui Wang, Tangwu Yang, Yumei Gu, Sheng Sheng, Dehua Zhao, Shuqing An and Aimin Li
Processes 2023, 11(5), 1469; https://doi.org/10.3390/pr11051469 - 12 May 2023
Cited by 1 | Viewed by 873
Abstract
Constructed wetlands (CWs) had been widely used to treat the tailwater from sewage treatment plants. However, the enduring effectiveness of CWs was still unclear. Therefore, this study aimed to investigate the chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), and total [...] Read more.
Constructed wetlands (CWs) had been widely used to treat the tailwater from sewage treatment plants. However, the enduring effectiveness of CWs was still unclear. Therefore, this study aimed to investigate the chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), and total phosphorus (TP) removal efficiencies (RE) of the Hongze CW (HZ-CW) after multi-years’ operation. The average COD RE were 7.6% and 15.14% in the 4th and 5th year, respectively. The NH4+-N RE was 78.33% and 46.04% in the 4th and 5th year, respectively, while the TP RE remained high at 66.86% and 64.68%. The high-throughput sequencing analysis revealed that the bacterial community of HZ-CW at the end of the 5th year exhibited a substantial abundance and diversity, and Proteobacteria and Bacteroidota were the dominant phyla with a relative abundance of 33.75–71.8% and 11.28–24.53% in different zones of HZ-CW. Ammonia oxidizing organisms (AOMs) presented much higher relative abundance (0.43–0.79%) in aerated pond (AP) and four free water surface flow CWs (FWS1–FWS4) than those of anammox bacteria, indicating the dominant role of nitrification in NH4+-N removal. Full article
(This article belongs to the Special Issue Advances in Remediation of Contaminated Sites: Volume II)
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11 pages, 2145 KiB  
Article
Analysis of Hydrochemical Characteristics and Causes of Drinking Water Sources in South China: A Case Study in Zhanjiang City
by Hang Wei, Qi Zou, Zhiliang Chen, Yingjie Cao, Shuang Wang, Fen Zhu and Xulong Liu
Processes 2023, 11(4), 1196; https://doi.org/10.3390/pr11041196 - 13 Apr 2023
Cited by 1 | Viewed by 868
Abstract
The evaluation of groundwater environmental quality and the identification of recharge sources are very important for groundwater utilization. In this study, hydrochemistry and isotope analysis methods are used to investigate the recharge sources and hydrochemical processes of groundwater in Zhanjiang City. The results [...] Read more.
The evaluation of groundwater environmental quality and the identification of recharge sources are very important for groundwater utilization. In this study, hydrochemistry and isotope analysis methods are used to investigate the recharge sources and hydrochemical processes of groundwater in Zhanjiang City. The results show that all samples of groundwater were drawn on the left of the global meteoric water line (GMWL: δD = 8δ18O + 10) and local meteorological water lines (LMWL1: δD = 8.17δ18O + 11.74 and LMWL2: δD = 7.50δ18O + 6.18), indicating that the groundwater was mainly recharged by meteoric precipitation and influenced by the effect of evaporation. In the middle and deep confined aquifers, the isotope data depleted with the depth, indicating that there is a relatively weak hydraulic connection between them. In addition, compared with unconfined groundwater, the isotope data of confined groundwater showed relative depletion, indicating that the confined aquifer may be partially recharged from other confined aquifers. The main chemical types in the groundwater were Na*Ca-HCO3. There are three major natural hydrochemical processes controlling the source of groundwater ions: silicate weathering, carbonate dissolution, and the cation exchange reaction. In addition, the differences in physical and chemical properties between unconfined groundwater and confined groundwater are significant. Due to the differences in anthropogenic activities and land-use types, the nitrate of the unconfined groundwater exceeds the groundwater standards. Due to the geological background of Zhanjiang City, iron and manganese exceed the third standard of groundwater in confined groundwater. Due to groundwater exploitation, TDS levels in confined groundwater have been increasing. Closed groundwater extraction is not sustainable, and it is depleting ancient water reserves. This study highlights the effectiveness of hydrochemistry and isotope analysis methods for identifying the recharge area and recharge mode of groundwater, andit is significant for fully understanding groundwater hydrochemistry and scientifically managing and protecting groundwater. Full article
(This article belongs to the Special Issue Advances in Remediation of Contaminated Sites: Volume II)
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15 pages, 4579 KiB  
Article
Analysis of Natural Groundwater Flowing into the Flow Field of In Situ Leaching Mining
by Qinci Li, Zhaokun Li, Tingting Xie, Ye Ding, Nan Gan, Yahui Tan and Chong Zhang
Processes 2023, 11(2), 471; https://doi.org/10.3390/pr11020471 - 03 Feb 2023
Cited by 1 | Viewed by 3629
Abstract
This paper aims to quantitatively analyze the influence of natural groundwater flowing into the flow field of in situ leaching mining. The computational method was built to evaluate the effect of natural groundwater on the production efficiency of pumping wells for the in [...] Read more.
This paper aims to quantitatively analyze the influence of natural groundwater flowing into the flow field of in situ leaching mining. The computational method was built to evaluate the effect of natural groundwater on the production efficiency of pumping wells for the in situ leaching of uranium, and the “flow ratio of groundwater” and related formulas were defined. C1 and C2 mining areas of an in situ leaching uranium mine in Inner Mongolia were taken as an example, and the effect on the “flow ratio of groundwater” when changing the flow quantity of injection wells and the position and length of the filter in the pumping and injection wells were compared. The results show that the variation in the “flow ratio of groundwater” of a whole mining area or a single pumping well in different production stages can be obtained by the neutral solution concentration value from the mining area’s numerical simulation. Regulating the position, length of the filter, and mode of fluid injection in an in situ leaching mine can control the quantity of natural groundwater flowing into the mining area and reduce the fluid exchange between the flow field of in situ leaching uranium mining and natural groundwater. Full article
(This article belongs to the Special Issue Advances in Remediation of Contaminated Sites: Volume II)
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16 pages, 2727 KiB  
Article
Differences in Physiological Metabolism and Antioxidant System of Different Ecotypes of Miscanthus floridulus under Cu Stress
by Jianqiao Qin, Zhiqiang Yan, Xueding Jiang, Huarong Zhao, Shasha Liu, Min Dai, Dexin Xiong and Xi Chen
Processes 2022, 10(12), 2712; https://doi.org/10.3390/pr10122712 - 15 Dec 2022
Viewed by 5809
Abstract
To reveal the similarities and differences in the resistance mechanisms of different ecotypes to Cu stress, a pot experiment was used to systematically compare the physiological responses of non-mining ecotype Miscanthus floridulus (collected from Boluo County, Huizhou City) and mining ecotype Miscanthus floridulus [...] Read more.
To reveal the similarities and differences in the resistance mechanisms of different ecotypes to Cu stress, a pot experiment was used to systematically compare the physiological responses of non-mining ecotype Miscanthus floridulus (collected from Boluo County, Huizhou City) and mining ecotype Miscanthus floridulus (collected from Dabaoshan mining area) under different Cu concentrations. The results showed that chlorophyll a, chlorophyll b and total chlorophyll in the leaves of the two ecotypes of M. floridulus were negatively correlated with Cu stress concentration (p < 0.01), but the extent of decrease for the ecotypes in the mining area was lower than that for the ecotypes in the non-mining area. The values of chlorophyll a/b for both ecotypes increased with increasing Cu treatment concentration, indicating that Cu is more harmful to chlorophyll b than to chlorophyll a for M. floridulus. Cu stress can lead to the accumulation of malondialdehyde (MDA) in the leaves of M. floridulus with the amount of MDA accumulation observed being greater in the non-mining ecotype than in the mining ecotype (p < 0.05). The content of antioxidant substances (ascorbic acid and reduced glutathione) in the mining ecotype M. floridulus was significantly higher than that in the non-mining ecotype. The activity of SOD in the leaves of non-mining ecotypes was inhibited by Cu stress and the activity of POD was increased by Cu stress. However, the increase in POD in the mining ecotypes was greater than that in the non-mining ecotypes and the activities of the two enzymes in the mining ecotypes were significantly higher than those in the non-mining ecotypes at the highest concentration of Cu. Cu had different effects on PPO activity in the leaves of the two ecotypes of M. floridulus. The plant leaves of the non-mining ecotype at 400 and 800 mg·kg−1 were significantly fewer than those of the control group (p < 0.05), which were 87.1% and 65.2% of the control group, respectively. The PPO activity in the plant leaves of the mining ecotype was higher than that in the leaves of the non-mining ecotype and was significantly higher at 400 and 800 mg·kg−1 than that of the control group (p < 0.05), at 226.5% and 268.1% of the control group, respectively. These results indicate that the mining ecotype M. floridulus is more resistant to copper stress, that resistant ecotypes have been formed, and that small-molecule antioxidant substances play an important role in increasing resistance levels. Full article
(This article belongs to the Special Issue Advances in Remediation of Contaminated Sites: Volume II)
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16 pages, 3166 KiB  
Article
A Computational Framework for Design and Optimization of Risk-Based Soil and Groundwater Remediation Strategies
by Xin Wang, Rong Li, Yong Tian, Bowei Zhang, Ying Zhao, Tingting Zhang and Chongxuan Liu
Processes 2022, 10(12), 2572; https://doi.org/10.3390/pr10122572 - 02 Dec 2022
Cited by 1 | Viewed by 6795
Abstract
Soil and groundwater systems have natural attenuation potential to degrade or detoxify contaminants due to biogeochemical processes. However, such potential is rarely incorporated into active remediation strategies, leading to over-remediation at many remediation sites. Here, we propose a framework for designing and searching [...] Read more.
Soil and groundwater systems have natural attenuation potential to degrade or detoxify contaminants due to biogeochemical processes. However, such potential is rarely incorporated into active remediation strategies, leading to over-remediation at many remediation sites. Here, we propose a framework for designing and searching optimal remediation strategies that fully consider the combined effects of active remediation strategies and natural attenuation potentials. The framework integrates machine-learning and process-based models for expediting the optimization process with its applicability demonstrated at a field site contaminated with arsenic (As). The process-based model was employed in the framework to simulate the evolution of As concentrations by integrating geochemical and biogeochemical processes in soil and groundwater systems under various scenarios of remedial activities. The simulation results of As concentration evolution, remedial activities, and associated remediation costs were used to train a machine learning model, random forest regression, with a goal to establish a relationship between the remediation inputs, outcomes, and associated cost. The relationship was then used to search for optimal (low cost) remedial strategies that meet remediation constraints. The strategy was successfully applied at the field site, and the framework provides an effective way to search for optimal remediation strategies at other remediation sites. Full article
(This article belongs to the Special Issue Advances in Remediation of Contaminated Sites: Volume II)
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