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Remediation of Contaminated Soil and Wastewater Treatment

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A special issue of Sustainability (ISSN 2071-1050). This special issue belongs to the section "Resources and Sustainable Utilization".

Deadline for manuscript submissions: closed (31 October 2023) | Viewed by 18939

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Special Issue Editors

Prof. Dr. Shengsen Wang

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Guest Editor

College of Environmental Science and Engineering, Yangzhou University, Yangzhou 225127, China
Interests: biochar preparation and charterization; soil and water remediation; tunable preparation and optimization of zerovalent iron; soil geochemistry of toxic metals; advanced oxidation technology; metal-free catalysts; environmental soil chemistry

Prof. Dr. Jun Wang

E-Mail Website
Guest Editor

College of Resources and Environment, Key Laboratory of Agricultural Environment in Universities of Shandong, Shandong Agricultural University, Taian 271018, China
Interests: soil remediation; geochemical process of heavy metals in soil; environmental toxicology

Special Issue Information

Dear Colleagues,

Soil and water contamination mainly results from improper discharge of heavy metals and organic pollutants such as pesticides, herbicides, antibiotics and etc. This was even aggregated by the high background level in soil and groundwater. The long-term exposure to these hazardous sustances is associated with serious chronic and acute diseases to humankind and causes concern to sustainability of ecological system. This has occurred in many regions across the world over the past few decades. Despite enmorous efforts for pollution abatement, the situation has been complicated by the newly-polluted sites and new synthetic organic compounds. Thus, there is an urgent need to understand the biogeochemical processes of these pollutants in soil and wastewater and then propose effective practices to abate the contamination.

This special issue aims to demonstrate the recent research advances on mitigation of environmental pollution for the sake of environmental sustainablity. In this special issue, original research articles and reviews are welcome. Research areas may include (but not limited to) the following:

Biogeochemical processes of heavy metals and fate of organics in soil and water, including the transformation of contaminants under changing environmental conditions (e.g., pH, redox), interactions of contamiannts with soils components as well as particles and sedments in water, and role of microbes;
Environmental nanotechnology for soil and water remediation, including the preparation methodology, performance, and reaction mechanisms with contaminants of state-of-art functional materials, such as carbonaceous materials and their derivatives (e.g., biochar, graphene-based materials, nitrogen-doped carbon materials and etc), metal-based nanoparticles (e.g., zerovalent iron and etc), organic polymers (e.g., hydrogels and etc) and carbon-metal composites (metal organic Framework (MOFs), carbon-supported metal nanoparticles, etc);
Detoxification techniques of polluted soil and wastewater, including (chemical, biological, thermal) immoblization, biological remediation such as phytoremediation and microbe-based techniques, advanced oxygen technology and other practices which could reduce the health risks of the contamiants in environment;
The adverse aspects or toxicology of contaminants to plants, animals, microbes and ecosystem.

We look forward to receiving your contributions.

Prof. Dr. Shengsen Wang
Prof. Dr. Jun Wang
Guest Editors

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Keywords

biochar
metal oxides
zerovalent iron
adsorption
degradation
environmental nanotechnology
soil and water remediation
heavy metals
advanced oxidation technology
metal-free catalysts

Published Papers (11 papers)

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Research

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17 pages, 1571 KiB

Open AccessArticle

Effects of Fertilizers and Conditioners on Chromium Uptake of Maize in Chromium-Polluted Farmland

by Jing Zheng, Xiaotian Zhou, Yuxin Gao, Chi Cao, Hanxiu Hu, Wenling Ye and Youhua Ma

Sustainability 2023, 15(17), 13011; https://0-doi-org.brum.beds.ac.uk/10.3390/su151713011 - 29 Aug 2023

Viewed by 752

Abstract

Using agronomic measures to remediate heavy metal chromium (Cr) on farmland is the main measure to achieve the safe utilization of crops. This study was conducted under field trial conditions using locally formulated fertilizers (urea–ammonium phosphate–potassium chloride) as the control. Different fertilizer-type treatments such as ammonium sulfite, calcium magnesium phosphate, and diammonium phosphate were set up. Biochar and soil conditioner PX5B were chosen to compare the impacts of each to study the effects of different fertilizer types on maize yield, Cr content in each part, the bioconcentration factor, the translocation factor, and the available content of Cr in the soil. The results show that, compared with the formulated fertilizer, all treatments improved pH and soil organic matter and reduced the effective state of Cr content in the soil by 15.05% to 42.66%. The Cr content of maize grains under biochar and soil conditioner PX5B treatments were 0.80 mg·kg⁻¹ and 0.88 mg·kg⁻¹ with a 39.95% and 33.83% reduction, respectively, whereas the Cr content of maize grains under various fertilizer treatments was in the range of 0.82~1.32 mg·kg⁻¹ with a 0.75%~38.19% reduction, respectively. Among the different fertilizer treatments, urea–calcium magnesium phosphate–potassium chloride, urea–diammonium phosphate–potassium chloride, ammonium sulfite–calcium magnesium phosphate–potassium chloride, and ammonium sulfite and urea–calcium magnesium phosphate–potassium chloride treatments reduced the Cr content of maize grains to within the range of the national food safety standard of China (1.0 mg·kg⁻¹). The best reductions in the effective state Cr content of the soil and the Cr content of maize grains were achieved by ammonium sulfite–calcium magnesium phosphate–potassium chloride treatment, which was able to achieve similar reductions to the two conditioners. It also had a reduction effect on the Cr content of maize roots and straws, the aboveground bioconcentration factor (BCF), and the primary translocation factor (PTF). Therefore, the combination of ammonium sulfite and calcium magnesium phosphate is the best fertilizer combination to block the absorption of Cr by maize and has some implications for the fertilization of farmland under acidic soil conditions of Cr contamination. Full article

(This article belongs to the Special Issue Remediation of Contaminated Soil and Wastewater Treatment)

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15 pages, 1699 KiB

Open AccessArticle

Effects of Formula Fertilizer and Biochar on Cadmium and Plumbum Absorption in Maize (Zea mays L.)

by Zhongwen Ma, Ronghao Tao, Jingyi Hu, Chi Cao, Zhaoyun Hu, Yong Chen, Hongxiang Hu and Youhua Ma

Sustainability 2023, 15(6), 4696; https://0-doi-org.brum.beds.ac.uk/10.3390/su15064696 - 7 Mar 2023

Cited by 4 | Viewed by 1322

Abstract

Effective, economical and feasible remediation technology of heavy metal pollution in farmland is an important research concentration in the field of farmland soil remediation. In order to investigate the remediation effects of formula fertilizer and biochar on cadmium (Cd)–plumbum (Pb) contaminated farmland, blank (CK), lime (SH), biochar (SWT), formula fertilizer (FL), and biochar + formula fertilizer (FS) were set up in Cd–Pb contaminated farmland. The results demonstrated the following: (1) Compared with CK, SWT and FS increased the yield by 11.21% and 15.00%, respectively, which was significantly higher than other treatments. (2) The concentrations of Cd and Pb in maize kernels under all treatments were lower than the limited value stipulated by GB 2762-2022 in China. Compared with CK, FS reduced the concentration of Cd and Pb in maize kernels by 24.96% and 31.46%, respectively, which were the most significant. All the treatments can reduce the concentrations of Cd and Pb in maize cob and straw and inhibit the transfer of Cd and Pb from the lower part of the maize field to the overground part. (3) FL, SWT, and FS increased soil pH by 0.17, 0.10, and 0.19 units, respectively. FS can reduce the concentrations of available cadmium (DTPA-Cd) and available lead (DTPA-Pb) significantly, which are 31.05% and 38.57% lower than CK, respectively. (4) Each treatment can reduce the extraction state and reducible state of weak acid Cd and Pb in soil, while increasing the proportion of oxidizable state and residual state. FL and FS significantly increased the percentage of residual Cd and Pb by 18.00% and 24.32%, respectively, and 33.33% and 37.76%, respectively. (5) FL (1.747) and FS (1.679) were relatively higher than CK in input/output. In conclusion, the combined application of biochar and formula fertilizer in Cd/Pb polluted farmland can effectively reduce the concentration of Cd and Pb in maize and has high economic benefits and practicability. Full article

(This article belongs to the Special Issue Remediation of Contaminated Soil and Wastewater Treatment)

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13 pages, 2041 KiB

Open AccessArticle

Effect of Leaf Surface Regulation of Zinc Fertilizer on Absorption of Cadmium, Plumbum and Zinc in Rice (Oryza sativa L.)

by Jingyi Hu, Ronghao Tao, Chi Cao, Junhao Xie, Yuxin Gao, Hongxiang Hu, Zhongwen Ma and Youhua Ma

Sustainability 2023, 15(3), 1877; https://0-doi-org.brum.beds.ac.uk/10.3390/su15031877 - 18 Jan 2023

Cited by 4 | Viewed by 1384

Abstract

The accumulation of heavy metals in rice is bound to affect human health and safety. In order to ensure food security, this study explores the effect of leaf surface regulation of zinc (Zn) fertilizer on the safety of rice in cadmium (Cd)-plumbum (Pb) polluted farmland. Through field experiments, the leaf surface control treatment of zinc fertilizer was set up, and the effects of leaf surface control of zinc fertilizer on rice yield, Cd and Pb concentration in different parts and zinc, nitrogen, phosphorus and potassium concentration in brown rice were studied in the growing period of rice. The results showed as follows: (1) Spraying twice or more in the growth stage of rice could increase the yield by 6.77–7.29% compared with the blank, which was significantly higher than that of single spraying in a certain growth stage. (2) After spraying zinc fertilizer on the leaf surface, Cd and Pb concentration in brown rice decreased by 29.52–56.01% and 11.10–28.34%, respectively, compared with CK. Two or more times of spraying can make Cd concentration in brown rice meet the Chinese standard GB 2762-2022, and one time of spraying can make Pb concentration in brown rice meet the standard. (3) Leaf surface control of zinc fertilizer could reduce the Cd enrichment ability of rice plant parts, and the Cd enrichment coefficient of brown rice was significantly reduced by 28.18–55.02%. Leaf surface control of zinc fertilizer can reduce Cd and Pb concentration in brown rice by reducing the transport ability of heavy metal Cd and Pb in rice roots to straw and then to brown rice. (4) The zinc concentration in brown rice was 18.16–20.68 mg·kg⁻¹, which was 18.21–34.64% higher than that in CK, and the zinc enrichment effect was the most significant after spraying three times. Meanwhile, the nitrogen, phosphorus and potassium concentration in brown rice also increased with the increase of spraying times. By comprehensive analysis, the leaf surface control of zinc fertilizer can reduce the Cd and Pb concentration in rice, and the Cd and Pb concentration in brown rice can meet the Chinese standard GB 2762-2022 by spraying twice. At the same time, it can improve the concentration of zinc, nitrogen, phosphorus and potassium in brown rice, is feasible and has high economic benefits. Full article

(This article belongs to the Special Issue Remediation of Contaminated Soil and Wastewater Treatment)

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16 pages, 1962 KiB

Open AccessArticle

Effectiveness of Passivator Amendments and Optimized Fertilization for Ensuring the Food Safety of Rice and Wheat from Cadmium-Contaminated Farmland

by Hanxiu Hu, Linlin Gao, Huimin Zhang, Xiaotian Zhou, Jing Zheng, Jingyi Hu, Hongxiang Hu and Youhua Ma

Sustainability 2022, 14(22), 15026; https://0-doi-org.brum.beds.ac.uk/10.3390/su142215026 - 14 Nov 2022

Viewed by 1138

Abstract

The effect of various soil amendments on cadmium (Cd)-contaminated farmland was evaluated in terms of effectiveness, safety, economics, and simplicity. Experiments were conducted in May 2020, on Cd-contaminated land in Tong Ling, An Hui, China. The efficacy of optimized fertilization and heavy metal passivators—gypsum, bamboo charcoal, lime, and a compound passivator (mixture of bamboo charcoal, silicon fertilizer, gypsum, furfural residue, plant ash, and chicken manure)—was evaluated as amendments to reduce the uptake of Cd in rice. The results indicate that all treatments reduced the Cd bioavailability in Cd-contaminated soil and rice grain Cd accumulation to levels that meet national food safety standards. Moreover, the rice yield increased by 4.80 to 14.27% and the Cd content in rice grains decreased by 23.53 to 36.83%. The efficacy of Cd reduction in rice was as follows: optimized fertilization > lime > compound passivator > bamboo charcoal > gypsum powder. Wheat was planted after the rice season to test the effect of the soil amendment measures implemented during the rice season on crop growth in the next season. Wheat yield improved by 3.46 to 10.96%, and the grain Cd content decreased by 6.47 to 41.03%. The efficacy of Cd reduction in wheat was as follows: lime > compound passivator > optimized fertilization > gypsum powder > bamboo charcoal. Following the lime treatment, the wheat grain Cd content met national food safety standards. A comprehensive comparison was conducted to evaluate the safe utilization and economic effect of the passivator and optimized fertilization. The results reveal that optimized fertilization was the most effective treatment. The findings from this study provide a scientific basis for safe rice–wheat rotation systems on mildly Cd-contained farmland (0.3 mg/kg < Cd < 1.0 mg/kg) in the Yangtze River Basin. Full article

(This article belongs to the Special Issue Remediation of Contaminated Soil and Wastewater Treatment)

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16 pages, 873 KiB

Open AccessArticle

Effect of LMWOAs on Maize Remediation of Cadmium and Plumbum Pollution in Farmland

by Ronghao Tao, Jingyi Hu, Chi Cao, Jing Zheng, Xiaotian Zhou, Hongxiang Hu, Youhua Ma, Wenling Ye, Zhongwen Ma and Hongjuan Lu

Sustainability 2022, 14(21), 14580; https://0-doi-org.brum.beds.ac.uk/10.3390/su142114580 - 6 Nov 2022

Cited by 5 | Viewed by 1509

Abstract

Plant extraction is a thorough remediation method to remove heavy metals from soil. Chelating agents can enhance the extraction effect of heavy metals from soil by plants. In this study, low molecular weight organic acids (LMWOAs), such as citric acid (CA), tartaric acid (TA) and polyaspartate (PASP), were added to the farmland soil contaminated with Cd and Pb and combined with corn to enhance the absorption and extraction of Cadmium (Cd) and Plumbum (Pb). The effects of LMWOAs on the growth and yield of maize, Cd and Pb concentrations in each part of maize, rhizosphere soil pH, total cadmium and lead content and DTPA-Cd and Pb concentrations were studied. The enrichment, transport and extraction ability of maize were analyzed, and calcium chloride (CaCl₂) was compared. The results showed that: (1) Exogenous LMWOAs increased the biomass and yield of maize compared with no material added (CK), and CA increased the yield of maize by 6.33%. (2) Exogenous LMWOAs promoted the uptake of Cd and Pb in all parts of maize, and the distribution of Cd and Pb in all organs was as follows: straws > roots > maize cobs > kernels and roots > straws > maize cobs > kernels. The Cd and Pb concentrations in maize kernels were in line with GB 13078-2017 in China, which could be used as feed maize. (3) Exogenous LMWOAs enhanced the enrichment of Cd and Pb in maize straws and roots. PASP had a good enrichment effect on Cd and Pb. CA and CaCl₂ could enhance the transport capacity of Cd and Pb from maize roots to straw. (4) Compared with CK, the total amount of Cd and Pb in rhizosphere soil decreased by 6.93–26.99% and 2.74–6.79%, respectively. LMWOAs could promote the concentration of DTPA-Cd and Pb in rhizosphere soil, and PASP had the most significant increase in DTPA-Cd and Pb in rhizosphere soil. Compared with CK, the soil pH value decreased by 0.03–0.14 units. LMWOAs can enhance the removal of heavy metals from maize, and PASP has the most significant comprehensive effect. Full article

(This article belongs to the Special Issue Remediation of Contaminated Soil and Wastewater Treatment)

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20 pages, 3905 KiB

Open AccessArticle

Activated Biochar Is an Effective Technique for Arsenic Removal from Contaminated Drinking Water in Pakistan

by Iftikhar Ahmad, Abdul Ghaffar, Ali Zakir, Zia Ul Haq Khan, Muhammad Farhan Saeed, Atta Rasool, Aftab Jamal, Adil Mihoub, Simone Marzeddu and Maria Rosaria Boni

Sustainability 2022, 14(21), 14523; https://0-doi-org.brum.beds.ac.uk/10.3390/su142114523 - 4 Nov 2022

Cited by 5 | Viewed by 2267

Abstract

Arsenic (As), the silent poison, is a widespread environmental pollutant which finds its way into drinking water supplies from natural or man-made sources and affects over 200 million people worldwide, including in Pakistan. It has been demonstrated that As causes serious health complications as well as social and economic losses. A quick, cost-effective, and simple method for efficiently filtering As from drinking water is urgently needed. The present study evaluates the ability of chemical treatment solutions to activate the sorption capacity of biochar derived from cotton stalks. The surface characteristics of CSB (cotton stalk biochar), HN-CSB (treated with nitric acid: HNO₃), and Na-CSB (treated with sodium hydroxide: NaOH) were investigated for their As sorption capacities and efficiency in removing As from contaminated drinking water. The chemical modification of biochar significantly increased the surface area and pore volume of CSB, with a maximum observed in HN-CSB (three times higher than CSB). Fourier-transform infrared spectroscopy (FTIR) analysis revealed several functional groups (OH⁻, −COOH, C=O, N-H) on CSB, though the chemical modification of biochar creates new functional groups on its surface. Results showed that the maximum sorption capacity of CSB was (q = 90 µg g⁻¹), of Na-CSB was (q = 124 µg g⁻¹) and of HN-CSB was (q = 140 µg g⁻¹) at an initial As concentration of 200 µg L⁻¹, an adsorbent dose of 1 g L⁻¹, with 4 h of contact time, a pH of 6 and a temperature of 25 ʰC. However, As removal was found to be 45–88% for CSB, 62–94% for Na-CSB and 67–95% for HN-CSB across all As concentrations. An isotherm model showed that As sorption results were best fitted to the Langmuir isotherm model in the case of CSB (Q_max = 103 µg g⁻¹, R² = 0.993), Na-CSB (Q_max = 151 µg g⁻¹, R² = 0.991), and HN-CSB (Q_max = 157 µg g⁻¹, R² = 0.949). The development of the largest surface area, a porous structure, and new functional groups on the surface of HN-CSB proved to be an effective treatment for As removal from contaminated drinking water. Both HN-CSB and Na-CSB are clearly cost-effective adsorbents under laboratory conditions, but HN-CSB is cheaper and more efficient in As removal than Na-CSB, allowing it to be used as a powerful and promising adsorbent for the removal of pollutants like Arsenic from aqueous solution. Full article

(This article belongs to the Special Issue Remediation of Contaminated Soil and Wastewater Treatment)

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10 pages, 1757 KiB

Open AccessArticle

Study on Chromium Uptake and Transfer of Different Maize Varieties in Chromium-Polluted Farmland

by Xiaotian Zhou, Hanxiu Hu, Chunyang Ying, Jing Zheng, Fuhong Zhou, Haoyong Jiang and Youhua Ma

Sustainability 2022, 14(21), 14311; https://0-doi-org.brum.beds.ac.uk/10.3390/su142114311 - 2 Nov 2022

Cited by 3 | Viewed by 1128

Abstract

The objective of this research was to study the differences in the enrichment and transport capacity of heavy metal chromium in farmland soil by different maize cultivars, and it is of great significance to screen out the maize varieties that meet the food safety standards and repair the heavy metal chromium in farmland soil. To complete the experiment, under the conditions of field experiments, 72 maize cultivars were selected to study the growth of maize in chromium-polluted arable land and the differences in Cr accumulation and transshipment of different maize cultivars. From the experiment, we found that among 72 maize varieties, 49 of them, accounting for 68.06% of the total, had kernel chromium content lower than the China kernel limit standard value of 1.0 mg kg⁻¹. There were significant differences in Cr content in the kernels, stems, leaves and roots of all cultivars, with Cr content in root > stems > kernels. The contents of Cr in roots and stems and kernels were 4.06–93.09 mg kg⁻¹ and 5.54–24.13 mg kg⁻¹ and 0.46–2.61 mg kg⁻¹, respectively, and the coefficients of variation were 51.21%, 36.36% and 46.11%. By cluster analysis, maize varieties were divided into five groups according to kernel chromium content, and the maize varieties were also divided into three categories according to the content of chromium in stem and leaf. At the same time, we found that the low accumulation of kernel, high accumulation of stem and leaf, seven varieties: Nongyu662, HongyuNO.9, Wankenyu125, Shuxinyu228, Kewei702, Liyu16, JinchengNo.6. The enrichment coefficients (BCF) of each maize cultivar ranged from 0.026 to 0.194, the transport coefficients TF (kernel/stem) and TF (stem/root) were between 0.028 and 0.064, and 0.064 and 0.864, and the enrichment coefficient and transport coefficient were less than 1. In the end, according to the comprehensive evaluation of the maize growth status, kernel Cr content, enrichment coefficient, transport coefficient and other indicators, it is believed that Nongyu662, HongyuNo.9, Wankenyu125, ShuXinYu228, Weike702, Liyu16, and JinchengNo.6 could be promoted as Cr maize cultivars with low kernel and high stem–leaf accumulation; also, planting these seven varieties can achieve the goal of restoring the heavy metal chromium in farmland soil while ensuring maize food security. Full article

(This article belongs to the Special Issue Remediation of Contaminated Soil and Wastewater Treatment)

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15 pages, 3866 KiB

Open AccessArticle

The Evaluation and Key-Factor Identification of the Influence of Tourism on the Soil of Mount Tai

by Fang Li, Kailai Wang, Xin Li, Haodong Zhang and Ying Li

Sustainability 2022, 14(21), 13929; https://0-doi-org.brum.beds.ac.uk/10.3390/su142113929 - 26 Oct 2022

Cited by 1 | Viewed by 1180

Abstract

Tourism has been proven to disturb the soil environments and stimulate heavy metal accumulation in scenic areas. Currently, research on the driving mechanisms of the impact of tourism on soil quality degradation is limited. Therefore, the aim of this study was to introduce a complex network method to comprehensively depict the impact of tourism on soil quality. To explore the key influencing factors, we collected 10 topsoil samples and 10 corresponding control samples from representative scenic areas in Mount Tai. Soil physicochemical properties (organic matter (OM), alkali dispelled nitrogen (AN), total nitrogen (TN), available phosphorus (AP), available potassium (AK), electrical conductivity (EC)), heavy metal (Cr, Cd, Pb, Hg, As, Cu) content, and microbial community diversity (by Eco-plate method) were analyzed. Additionally, complex networks of soil quality variables were established based on Pearson correlation coefficients. The results show that the OM, AN, and AP contents of scenic areas are 1.2, 1.03 and 1.18 times higher, while the AK content is 0.97 times lower, than those of the control sites, respectively (mean values of samples from scenic area vs. contorl sites). The single factor index of Hg, As, Pb, Cd, Cu, and Cr are increased from 3.65, 0.53, 0.85, 1.25, 0.78 and 0.58 to 3.69, 0.57, 1.24, 1.75, 0.97, 0.63 and 3.19, respectively, which means that tourism significantly exacerbates soil heavy metal accumulation. Additionally, the soil microbial activity and diversity are slightly reduced due to tourism. In general, the difference in the mean value of each soil quality variable between the scenic spot and the control site is not significant. However, tourism significantly reduced the connectivity and integrity of soil quality variables, which ultimately destabilized the soil, inferred from the comparison of the network’s topological parameters. Therefore, raising the content of soil OM and AN and controlling Cd pollution should be given more priority in soil ecosystem protection to counteract the negative impact of tourism on Mount Tai. It was the major limitation of the study that few typical scenic spots were selected as sampling points on Mount Tai. However, this study is sufficient to show that the complex network approach can be extended to other similar studies of soil quality degradation driving mechanisms. Full article

(This article belongs to the Special Issue Remediation of Contaminated Soil and Wastewater Treatment)

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11 pages, 2010 KiB

Open AccessArticle

Effects of the Combined Application of Chinese Milk Vetch (Astragalus sinicus L.) and Red Mud to Remediate the Cadmium-Polluted Acidic Paddy Soil

by Meirong Fan, Xin Liu, Yaoyu Zhou, Avelino Núñez-Delgado, Lin Luo, Shiping Long, Huang Huang, Li Hu and Yulin Liao

Sustainability 2022, 14(20), 13192; https://0-doi-org.brum.beds.ac.uk/10.3390/su142013192 - 14 Oct 2022

Viewed by 1368

Abstract

In this study, we conducted field experiments to assess the effects of the combined application of Chinese milk vetch (Astragalus sinicus L., CMV) and red mud (RM) to remediate the cadmium-polluted acidic paddy soil. The results showed that the combined application increased the yield component index and improved the grain yields, compared with the control, RM1, RM2, and CMV treatments. However, the increased range of soil pH values in the CMV-RM1 and CMV-RM2 treatments was smaller than that of the RM1 and RM2 treatments at the different rice growth stages. The soil organic matter (SOM) contents of the RM-only treatments did not differ throughout the whole period, but were significantly different (p < 0.05) between CMV-RM2 and the control. Compared with the control, the combined application decreased the concentration of exchangeable Cd in the early rice soil. The combined application of CMV and RM substantially decreased the rice uptake of Cd. However, we found no significant difference (p < 0.05) between the CMV-RM1 and CMV-RM2 treatments. Therefore, compared with remediation with RM or CMV alone, we recommend the combined application of CMV and RM as an economical, highly effective, and replicable amendment for remediating acidic, Cd-polluted paddy soil. Considering the restorative effect and proper use of RM, we recommend CMV-RM1 treatment. Full article

(This article belongs to the Special Issue Remediation of Contaminated Soil and Wastewater Treatment)

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14 pages, 2618 KiB

Open AccessArticle

Biofilm Structural and Functional Features on Microplastic Surfaces in Greenhouse Agricultural Soil

by Yue Chen, Xiaobing Wang, Xiaoli Wang, Tong Cheng, Kuankuan Fu, Zhentian Qin and Ke Feng

Sustainability 2022, 14(12), 7024; https://0-doi-org.brum.beds.ac.uk/10.3390/su14127024 - 8 Jun 2022

Cited by 20 | Viewed by 3346

Abstract

Microplastics (MPs) enter the soil through a variety of pathways, including plastic mulching, sludge, and organic manure application. In recent years, domestic and foreign experts and scholars have been concerned about the residues and contamination of MPs in the soil of greenhouse agriculture. In this investigation, five types of MPs including low-density polyethylene (LDPE), high-density polyethylene (HDPE), polystyrene (PS), polypropylene (PP), and polyethylene terephthalate (PET), and two concentrations (1% and 5%, w/w) were used in a 30-day external exposure test. Evidence of microbial enrichment was found on the surface of the MPs. The total amount of biofilm on the surface of MPs increased dramatically with increasing exposure time and MP concentrations. The polysaccharide content of extracellular polymers (EPS) in biofilms was significantly different, and the maximum PS1 (1% (w/w) PS) concentration was 50.17 mg/L. However, EPS protein content did not change significantly. The dominant bacteria on the surface of MPs with different types and concentrations were specific, and the relative abundance of Patescibacteria was significantly changed at the phylum level. At the genus level, Methylophaga, Saccharimonadales, and Sphingomonas dominated the flora of LDPE1 (1% (w/w) LDPE), PS1, and PET5 (5% (w/w) PET). The dominant bacteria decompose organic materials and biodegrade organic contaminants. According to the FAPROTAX functional prediction study, chemoheterotrophy and aerobic chemoheterotrophyplay a role in ecosystem processes such as carbon cycle and climate regulation. The application of LDPE1 has a greater impact on the carbon cycle. Plant development and soil nutrients in greenhouse agriculture may be influenced by the interaction between MPs and microorganisms in the growing area, while MP biofilms have an impact on the surrounding environment and pose an ecological hazard. Full article

(This article belongs to the Special Issue Remediation of Contaminated Soil and Wastewater Treatment)

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Review

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11 pages, 1561 KiB

Open AccessReview

Advances in the Effects of Biochar on Microbial Ecological Function in Soil and Crop Quality

by Yaming Zhao, Xiangjun Wang, Guangwei Yao, Zhizhong Lin, Laiyuan Xu, Yunli Jiang, Zewen Jin, Shengdao Shan and Lifeng Ping

Sustainability 2022, 14(16), 10411; https://0-doi-org.brum.beds.ac.uk/10.3390/su141610411 - 22 Aug 2022

Cited by 13 | Viewed by 2207

Abstract

Biochar, a late-model environmental functional material, has been widely applied in environmental remediation, agricultural production, and energy utilization due to its excellent characteristics such as porosity and high specific surface area. In recent years, many studies on the effects of biochar on agricultural soil and crop quality have been performed. The application of biochar can influence soil microbial status directly or indirectly by changing the physicochemical properties of soil. Apart from increasing soil pH, biochar can also increase soil organic matter and nutrient elements, which ultimately affect crop yield and quality. This review summarizes and overviews the recent research advances on the influence of biochar application on soil microbial community diversity, microbial ecological functions, soil enzymes and their functional genes, and on crop quality and yield from the perspective of soil microorganisms. This review provides guidance and references for further research into biochar applications. Full article

(This article belongs to the Special Issue Remediation of Contaminated Soil and Wastewater Treatment)

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