Soil and Water Pollution Process and Remediation Technologies

Topic Information

Dear Colleagues,

Since the twentieth century, large amounts of toxic organic and inorganic pollutants were released to pedosphere, hydrosphere, and biosphere from irrational anthropogenic socioeconomic activities, resulting in serious hazards to ecological environment and public health. Particularly, a large amount of pollutants were emitted into soil and water, causing extremely threats to food supply and water safety. Nevertheless, the pollutants source apportionment, migration, transformation of contaminants in soil and water are not well understood and security utilization of the polluted soil and water requires proper remediation technology.

At present, the remediation of polluted soil and water is upon on the degree of environmental risk. The first and foremost issue of carrying out environmental remediation is to clarify the source apportionment and migration route of pollutants. Through various physical, chemical, and biological remediation technologies, the polluted soil and water can be reused as agricultural land, construction land, domestic water, industrial water and etc. Meanwhile, the quality transformation of soil and water before and after remediation and its microbiological mechanism have received little attention. Therefore, it is urgent to seek novel remediation technologies and study how to reuse the natural resources. 

Herein, the toxic pollutants in this Topic “Soil and water pollution process and remediation technologies” focuses on the heavy metals, excess nutrient elements, pesticides, antibiotics, environmental hormones, antibiotics resistance genes, pathogens, microplastics, microbial communities and etc. We are pleased to invite you to contribute a manuscript to this Topic in the Journals International Journal of Environmental Research and Public Health (IJERPH), Water, Agronomy, Environments, Pollutants. Contributors are welcome to submit reviews and original research articles, including but not limited to the following topics:

• The source apportionment, pollution process, migration, transformation, and environmental risk of inorganic and organic pollutants in soil and water.
• Remediation technologies of the polluted soil and water.
• Environmental quality transformation and microbiological remedying mechanism in the polluted soil and water.

We are looking forward to receiving your contributions.

Dr. Hongbiao Cui
Prof. Dr. Yu Shi
Prof. Dr. Haiying Lu
Dr. Lin Chen
Dr. Ru Wang
Topic Editors

Participating Journals

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Agronomy agronomy	3.7	5.2	2011	15.8 Days	CHF 2600
Environments environments	3.7	5.9	2014	23.7 Days	CHF 1800
International Journal of Environmental Research and Public Health ijerph	-	5.4	2004	29.6 Days	CHF 2500
Pollutants pollutants	-	-	2021	21.7 Days	CHF 1000
Water water	3.4	5.5	2009	16.5 Days	CHF 2600

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Published Papers (29 papers)

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Supplementary material:
Supplementary File 1 (ZIP, 219 KiB)

19 pages, 2902 KiB  

Open AccessArticle

Effect of Different Livestock Manure Ratios on the Decomposition Process of Aerobic Composting of Wheat Straw

by Tingyu Fan, Xuemiao Zhang, Yi Wan, Ruilai Deng, Houhong Zhu, Xihao Wang, Shun Wang and Xingming Wang

Agronomy 2023, 13(12), 2916; https://doi.org/10.3390/agronomy13122916 - 27 Nov 2023

Cited by 2 | Viewed by 931

Abstract

Aerobic composting is an effective method of resource treatment for agricultural and forestry solid waste; however, while wheat straw is usually used as a conditioner and is not the main body as in aerobic composting, wheat straw is abundant in annual production, and [...] Read more.

Aerobic composting is an effective method of resource treatment for agricultural and forestry solid waste; however, while wheat straw is usually used as a conditioner and is not the main body as in aerobic composting, wheat straw is abundant in annual production, and fertilization is one of the main ways of resource utilization of wheat straw, how to use wheat straw as the main body of aerobic composting for efficient treatment is, therefore, a meaningful research direction. In this paper, to achieve the efficient and economic resource utilization of wheat straw and livestock manure, aerobic composting was carried out with wheat straw as the main body, and pig manure and cow manure were mixed with wheat straw crops at ratios of 20%, 30%, and 40%, respectively, for barrel suspension composting. The changes in pH, EC, NH₄⁺-N, NO₃⁻-N, TN, TP, organic matter and seed germination index, and shoot length inhibition rate before and after composting were compared between treatment groups using different material ratios in the aerobic composting process. The changes in the physicochemical properties and nutrient elements of compost products were studied. The results show that the co-composting of livestock manure and wheat straw can promote the decomposition of the pile, and the addition of 40% cow manure and 30% pig manure has the best effect in promoting decay. In contrast, the addition of excessive pig manure inhibits the decomposition of the pile. Organic matter degradation in the treatment groups using cow manure was more effective than in those using pig manure, and the best results were obtained with 40% cow manure. The pile was alkaline at the end of each treatment, and the wheat straw compost treated with 40% cow manure had the best nitrogen and phosphorus retention. The wheat straw compost treated with 40% cow manure had the highest integrated degree of decomposition, which promoted the deterioration of the pile and provided a research basis for the use of wheat straw as an efficient resource. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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Supplementary File 1 (ZIP, 396 KiB)

12 pages, 6514 KiB  

Open AccessArticle

Impacts of Modified Fly Ash on Soil Available Lead and Copper and Their Accumulation by Ryegrass

by Hongbiao Cui, Xue Sheng, Shaojun Hu, Shuai Li, Shiwen Zhang and Jun Zhou

Agronomy 2023, 13(9), 2194; https://doi.org/10.3390/agronomy13092194 - 22 Aug 2023

Viewed by 834

Abstract

Fly ash (FA) is promising for environmental remediation, but how to modify the FA with high remediation efficiency through an environmentally friendly and low-cost modification method is scare. A modified FA (MFA) was prepared through a one-step hydrothermal modification with Ca(OH)₂ and [...] Read more.

Fly ash (FA) is promising for environmental remediation, but how to modify the FA with high remediation efficiency through an environmentally friendly and low-cost modification method is scare. A modified FA (MFA) was prepared through a one-step hydrothermal modification with Ca(OH)₂ and KH₂PO₄. Results indicated that irregular agglomerates occurred on the surface of the MFA and that the specific surface area increased by 1.94 times compared to that of FA. Compared to FA, glassy compositions in MFA were destroyed and amorphous Si/Al and alkaline aluminosilicate gels were formed. The soil application of 0.2–0.6% MFA significantly increased soil pH by 0.23–0.86 units compared to FA and decreased available lead (Pb) and copper (Cu) by 25–97.1% and 13.5–75%, respectively. MFA significantly decreased exchangeable Pb and Cu by 12.5–32% and 11.4–35.2%, respectively, compared to FA. This may be due to the high pH and specific surface area of MFA, which promoted to the formation of amorphous Si/Al, metal–phosphate precipitation, and complexation with functional groups. In addition, MFA slightly increased the biomass of shoots and roots and decreased the uptake of Pb and Cu by ryegrass. This study provides a new modification method for the utilization of FA in the heavy metal-contaminated soils. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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13 pages, 1229 KiB  

Open AccessArticle

Denitrification Assays for Testing Effects of Xenobiotics on Aquatic Denitrification and Their Degradation in Aquatic Environments

by Kristína Pániková, Gabriele Weigelhofer, Zuzana Bílková and Jitka Malá

Water 2023, 15(14), 2536; https://doi.org/10.3390/w15142536 - 11 Jul 2023

Cited by 1 | Viewed by 999

Abstract

We developed, tested, and optimized two laboratory denitrification assays for both managers and scientists to assess the effects of xenobiotics on the denitrification process over 7 days (short batch assay, SBA) and 28 days (long semi-continuous assay, LSA). The assays facilitate (1) measuring [...] Read more.

We developed, tested, and optimized two laboratory denitrification assays for both managers and scientists to assess the effects of xenobiotics on the denitrification process over 7 days (short batch assay, SBA) and 28 days (long semi-continuous assay, LSA). The assays facilitate (1) measuring the efficiency of nitrate removal under the influence of xenobiotics, (2) determining the removal of the tested xenobiotics via adsorption or biotic decomposition, and (3) testing the influencing parameters for optimizing the denitrification process. The adsorption of the xenobiotics was assessed by inhibiting all biological processes through the addition of HgCl₂. Our tests demonstrate that the ratio of the initial nitrate concentration to the amount of bioavailable organic matter provided is essential to avoid organic carbon or nitrate limitation. While a pH < 7 resulted in decreased denitrification, a pH > 8 led to nitrite accumulation, indicating incomplete denitrification. Over durations of more than a week, weekly replenishments of the nitrate and HgCl₂ and weekly purging with argon gas to reduce the oxygen concentrations are needed. The assays provide information about the accumulation of xenobiotics in the bioreactors that is necessary for the environmentally friendly treatment of the bioreactor fillings and provide insight into the potential of the bioreactors to remove pesticides from polluted water resources. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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10 pages, 3174 KiB  

Open AccessCommunication

Biofilm Reactor with Permeable Materials as Carriers Archives Better and More Stable Performance in Treatment of Slightly Polluted Water during Long-Term Operation

by Zhichang Ren, Yangqi Zhou, Zichuan Lu, Xuechun Liu and Guoqiang Liu

Water 2023, 15(13), 2415; https://doi.org/10.3390/w15132415 - 29 Jun 2023

Viewed by 1076

Abstract

Biofilms in reactors usually grow on impermeable surfaces, and the mass transfer of nutrients in biofilms is mainly driven by diffusion, which is inefficient especially for thick biofilms. In this study, permeable materials (i.e., nylon meshes) were used as biocarriers in a biofilm [...] Read more.

Biofilms in reactors usually grow on impermeable surfaces, and the mass transfer of nutrients in biofilms is mainly driven by diffusion, which is inefficient especially for thick biofilms. In this study, permeable materials (i.e., nylon meshes) were used as biocarriers in a biofilm reactor, and their performance was evaluated and compared with the commercial biocarriers (PE08 and PE10) used for treating slightly polluted water. The results indicate that the mesh-based bioreactor achieved complete nitrification faster than the commercial biocarriers, with a more stable and better effluent quality during long-term operation. At a two-hour hydraulic retention time, the average effluent ammonia (NH₄⁺-N) and nitrite (NO₂⁻-N) concentrations during the stabilized phase were 0.97 ± 0.79 and 0.61 ± 0.32 mg-N, respectively, which are significantly lower than those with commercial carriers. The estimated specific surface area activities for the mesh, PE08, and PE10 carriers were 1620, 769, and 1300 mg-N/(m²·d)), respectively. The biofilms formed on the nylon mesh were porous, while they were compact and nonporous on the PE carriers. Water with substrates might pass through the porous biofilms formed on the meshes, which could enhance mass transfer and result in a better and more stable treatment performance. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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18 pages, 2601 KiB  

Open AccessArticle

Cadmium Accumulation and Immobilization by Artemisia selengensis under Different Compound Amendments in Cadmium-Contaminated Soil

by Huiyan Wang, Zhou Gao, Xun Li and Zengqiang Duan

Agronomy 2023, 13(4), 1011; https://doi.org/10.3390/agronomy13041011 - 29 Mar 2023

Viewed by 1464

Abstract

Cadmium (Cd) contamination is a global environmental challenge that threatens human food security. Lime combined with five different organic materials (rape seed cake, mushroom residue, straw, sawdust, and corn cobs) (LOM) at application ratios of 1:1 and lime sawdust combined with nitro-compound fertilizer [...] Read more.

Cadmium (Cd) contamination is a global environmental challenge that threatens human food security. Lime combined with five different organic materials (rape seed cake, mushroom residue, straw, sawdust, and corn cobs) (LOM) at application ratios of 1:1 and lime sawdust combined with nitro-compound fertilizer (Ca(NO₃)₂·4H₂O, KH₂PO₄, KNO₃) (LSF) at different application rates were applied to Cd-contaminated soil. The present study investigates the effects of these organic–inorganic compound amendments on Cd bioavailability in soil, and Cd uptake and accumulation by edible Artemisia selengensis parts. A. selengensis was cultivated for three consecutive seasons in Cd-contaminated soil. LOM and LSF treatments obviously reduced the uptake and accumulation of Cd. Compared with the control soil, contents of Cd in edible parts of A. selengensis decreased by 19.26–33.33% and 26.67–32.78% in the first season, 18.60–32.79% and 18.37–32.79% in the second season, and 20.45–40.68% and 34.32–37.27% in the third season, respectively. The addition of Lime + Mushroom Residue and 70% Nitro-compound Fertilizer + Lime + Sawdust most significantly reduced Cd concentrations in the edible parts of the third A. selengensis season. LOM and LSF application increased soil pH and improved soil fertility, including available nitrogen, available phosphorus, available potassium, organic matter, and cation exchange capacity. Lime + Mushroom Residue improved plant yield the most. In addition, Lime + Mushroom Residue and 70% Nitro-compound Fertilizer + Lime + Sawdust had the lowest Cd accumulation and health risk indices, respectively. In conclusion, the Lime + Mushroom Residue and 70% Nitro-compound Fertilizer + Lime + Sawdust amendments significantly reduced health risks, enhanced A. selengensis growth, and promoted sustainable development of arable land under Cd-contaminated soil remediation. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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14 pages, 3187 KiB  

Open AccessArticle

Remediation of Cd and Cu Contaminated Agricultural Soils near Oilfields by Biochar Combined with Sodium Humate-Wood Vinegar

by Junqi Wang, Weichun Gao, Junfeng Zhu, Yuxiao Yang and Yuhua Niu

Agronomy 2023, 13(4), 1009; https://doi.org/10.3390/agronomy13041009 - 29 Mar 2023

Cited by 2 | Viewed by 1293

Abstract

Soil contaminations by heavy metals near oilfields have been widely reported and are causing great concern. Thus, it is highly desirable to develop cost-effective materials and methods to avoid heavy metal residues contaminating soil and food. An effective, environmentally friendly, and inexpensive remediation [...] Read more.

Soil contaminations by heavy metals near oilfields have been widely reported and are causing great concern. Thus, it is highly desirable to develop cost-effective materials and methods to avoid heavy metal residues contaminating soil and food. An effective, environmentally friendly, and inexpensive remediation material for heavy metal-polluted soil was designed and prepared using biochar (BC) combined with humic acid (HA) resulting from sodium humate (NaHA) simply reacting with wood vinegar (BHW). After adding BHW, the chemical fractions of copper and cadmium in the soil undergo larger changes. Meanwhile, the availability of heavy metals decreases. The maximum adsorption capacity of copper and cadmium in the soil using the BHW is larger than that only using biochar. The adsorption kinetics ensures that the adsorption process of Cd²⁺ and Cu²⁺ ions on BHW is chemical adsorption, which is best fitted using the pseudo-second-order rate equation. The thermodynamics guarantees that the metal ions adsorb on the heterogeneous surface of BHW in multilayer, which is credited to the enhancement of oxygen-containing groups in the biochar combined with the humic acid. The remediation material BHW holds promise for the immobilization of heavy metal in the soils and could be recommended based on its economic feasibility, high efficacy, and environmental safety. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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17 pages, 4444 KiB  

Open AccessArticle

Impacts of Land Cover Change on the Spatial Distribution of Nonpoint Source Pollution Based on SWAT Model

by Zeshu Zhang, Hubert Montas, Adel Shirmohammadi, Paul T. Leisnham and Masoud Negahban-Azar

Water 2023, 15(6), 1174; https://doi.org/10.3390/w15061174 - 18 Mar 2023

Cited by 3 | Viewed by 1508

Abstract

Nonpoint source (NPS) pollution is a pressing issue worldwide, especially in the Chesapeake Bay, where sediment, nitrogen (N), and phosphorus (P) are the most critical water quality concerns. Despite significant efforts by federal, state, and local governments, the improvement in water quality has [...] Read more.

Nonpoint source (NPS) pollution is a pressing issue worldwide, especially in the Chesapeake Bay, where sediment, nitrogen (N), and phosphorus (P) are the most critical water quality concerns. Despite significant efforts by federal, state, and local governments, the improvement in water quality has been limited. Investigating the spatial distribution of NPS hotspots can help understand NPS pollutant output and guide control measures. We hypothesize that as land cover changes from natural (e.g., forestland) and agricultural to suburban and ultra-urban, the distribution of NPS pollution source areas becomes increasingly spatially uniform. To test this hypothesis, we analyzed three real watersheds with varying land cover (Greensboro watershed for agriculture, Watts Branch watershed for suburban, and Watershed 263 for ultra-urban) and three synthetic watersheds developed based on the Watts Branch watershed, which ranged from forested and agricultural to ultra-urban but had the same soil, slope, and weather conditions. The Soil and Water Assessment Tool (SWAT) was selected as a phenomenological model for the analysis, and SWAT-CUP was used for model calibration and validation. The hydrologic responses of the three real and synthetic watersheds were simulated over ten years (1993–2002 or 2002–2011), and calibration and validation results indicated that SWAT could properly predict the export of runoff and three target NPS pollution constituents (sediment, total nitrogen, and total phosphorus). The results showed that the distribution of NPS pollutant outputs becomes increasingly uniform as land cover changes from agriculture to ultra-urban across watersheds. This research suggests that the spatial distribution of NPS pollution source areas is a function of the major land cover category of study watersheds, and control strategies should be adapted accordingly. If NPS pollution is distributed unevenly across a watershed, hotspot areas output a disproportionate amount of pollution and require more targeted and intensive control measures. Conversely, if the distribution of NPS pollution is more uniform across a watershed, the control strategies need to be more widespread and encompass a larger area. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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17 pages, 6331 KiB  

Open AccessArticle

The Changes of Tolerance, Accumulation and Oxidative Stress Response to Cadmium in Tobacco Caused by Introducing Datura stramonium L. Genes

by Keqiang Wei and Tingting Guo

Agronomy 2023, 13(3), 882; https://doi.org/10.3390/agronomy13030882 - 16 Mar 2023

Viewed by 1293

Abstract

Whether it is possible to create suitable plants for cadmium phytoremediation by introducing Datura stramonium L. genes into tobacco (Nicotiana tabacum L.) remains unclear. Hydroponic experiments were performed on N. tabacum L. var. MTLY, a newly developed hybrid variety, and the parents. [...] Read more.

Whether it is possible to create suitable plants for cadmium phytoremediation by introducing Datura stramonium L. genes into tobacco (Nicotiana tabacum L.) remains unclear. Hydroponic experiments were performed on N. tabacum L. var. MTLY, a newly developed hybrid variety, and the parents. Seedlings at the six-leaf stage were treated with 0 (control), 10 µM, 180 µM and 360 µM CdCl₂ for 7 days, and their differences in Cd tolerance and accumulation and physiological and metabolic responses were evaluated. When subjected to 360 µM Cd, the growth of “MTLY”, in terms of the dry weight, plant height and root length, was obviously better than N. tabacum L. var. LY2 (female parent). In contrast to D. stramonium (male parent) and “LY2”, “MTLY” accumulated more Cd in shoots (127.6–3837.1 mg kg⁻¹) and roots (121.6–1167.7 mg kg⁻¹). Moreover, unlike “LY2”, “MTLY” could accumulate more Cd in its shoots than roots. Its bioconcentration factor (BCF) and translocation factor (TF) values reached 95.9–149.7 and 1.0–3.5, respectively, which were far greater than those of “LY2”. High-dose Cd stress significantly increased reactive oxygen species (ROS) and malondialdehyde (MDA) levels and decreased chlorophyll contents in tobacco seedlings, especially in “LY2”. Various enzymatic and non-enzymatic antioxidants in the three materials showed different responses to Cd stress. The change of the phenolic compounds and alkaloids in “MTLY” was basically similar to that in D. stramonium, but their levels were apparently higher than those in “LY2”. Results indicated that distant hybridization could be one of the effective methods for introducing metal-hyperaccumulator genes into a high biomass species, which contributed to enhancing the Cd tolerance, accumulation and detoxification in tobacco. This study has great significance in obtaining elite germplasm for phytoremediation. The exact mechanisms in molecules and genetics and the practical effectiveness in cadmium-contaminated soil remain to be further elucidated. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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19 pages, 4030 KiB  

Open AccessArticle

Ions Transport in Seasonal Frozen Farmland Soil and Its Effect on Soil Salinization Chemical Properties

by Yawen Liu, Jingwei Wu, Hang Zhao, Changsen Li, Jun Mao, Rui Zhang, Jie Liu and Qiang Zhao

Agronomy 2023, 13(3), 660; https://doi.org/10.3390/agronomy13030660 - 24 Feb 2023

Viewed by 1082

Abstract

The salinization of farmland soil is exacerbated during the freeze–thaw (FT) process, endangering agricultural production. The change of soil salt ions results in the formation and development of soil salinization. The objectives of this study were to investigate the migration characteristics of salt [...] Read more.

The salinization of farmland soil is exacerbated during the freeze–thaw (FT) process, endangering agricultural production. The change of soil salt ions results in the formation and development of soil salinization. The objectives of this study were to investigate the migration characteristics of salt ions during the FT process, identify the effects of inconsistencies in ions transport on the development of soil salinization chemical properties. A six-month field observation was conducted from November 2020 to April 2021 in the Hetao Irrigation District, China, a typical seasonally frozen soil area affected by salinization. Soil salt ions, soil moisture content (SMC), soil temperature, and pH were measured. Soil salt content (SSC), sodium adsorption ratio (SAR) were calculated. The ions accumulated in the frozen soil layer during the freezing period in the order of Cl⁻ > Mg²⁺ > Ca²⁺ > Na⁺ > SO₄²⁻, and accumulated in the topsoil during the thawing period in the order of Cl⁻ > Na⁺ > Mg²⁺ > Ca²⁺ > SO₄²⁻, while the change in HCO₃⁻ was mostly the opposite. The FT process changed the main salt anions from sulfate to chloride. After the FT process, the topsoil was endangered by high salinization, excess Cl⁻ toxicity, and a potential alkalization threat. This study has great guiding significance for the management and control of soil salinization before spring sowing in saline areas. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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10 pages, 1565 KiB  

Open AccessCommunication

Effects of Solids Accumulation on Greenhouse Gas Emissions, Substrate, Plant Growth and Performance of a Mediterranean Horizontal Flow Treatment Wetland

by Alessandro Sacco, Liviana Sciuto, Feliciana Licciardello, Giuseppe L. Cirelli, Mirco Milani and Antonio C. Barbera

Environments 2023, 10(2), 30; https://doi.org/10.3390/environments10020030 - 13 Feb 2023

Cited by 1 | Viewed by 2173

Abstract

In treatment wetlands (TWs), solids accumulation can result in hydraulic malfunction, reducing the operation life, and it could enhance biological activity by favoring biofilm development. It is still unknown whether the solids accumulation can affect greenhouse gas (GHG) emissions. This study aims to [...] Read more.

In treatment wetlands (TWs), solids accumulation can result in hydraulic malfunction, reducing the operation life, and it could enhance biological activity by favoring biofilm development. It is still unknown whether the solids accumulation can affect greenhouse gas (GHG) emissions. This study aims to evaluate the solid concentration along a horizontal flow (HF) TW, and its role in GHG emissions, hydraulics, treatment performance, and vegetation development (Phragmites australis (Cav.) Trin. ex Steud.). The study was carried out in an eight-year-old full-scale HF-TW located in the Mediterranean region (Sicily, Italy). To collect data inside the HF unit, nine observation points (besides the inlet and the outlet) along three 8.5-m-long transects (T1, T2, and T3) were identified. The first transect (close to the inlet zone) showed a hydraulic conductivity (Ks) reduction approximately one order of magnitude higher than the other two. Results highlighted that GHG emissions increased during the summer, when the temperature and solar radiation were higher than in the rest of the year, matching the macrophyte growth rate. Theoretical methane (CH₄) emissions followed the trend of volatile solids (VS), which was around 3.5 and 4 times in T1 to T2 and T3. Pore clogging affected carbon dioxide (CO₂) emissions, which decreased from T1 to T3, with maximum monthly values in T1 (21.4 g CO₂·m⁻²·d⁻¹) being approximately double with respect to T2 (12.6 g CO₂·m⁻²·d⁻¹) and T3 (10.7 g CO₂·m⁻²·d⁻¹) observed in July. The same trend for chemical oxygen demand (COD) removal efficiency, decreasing from T1 to T3, was observed. Notwithstanding this behavior, the final effluent quality was very satisfactory, with an average value of COD removal efficiency above 90%. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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Supplementary File 1 (ZIP, 7137 KiB)

12 pages, 4326 KiB  

Open AccessArticle

Slow-Release Lanthanum Effectively Reduces Phosphate in Eutrophic Ponds without Accumulating in Fish

by Callie McCright, Jenna McCoy, Natalie Robbins and Steve Comfort

Environments 2023, 10(2), 20; https://doi.org/10.3390/environments10020020 - 27 Jan 2023

Cited by 1 | Viewed by 3383

Abstract

Nutrient runoff is a major water quality issue affecting water resources. Excess nutrients such as nitrate (NO₃⁻) and phosphate (PO₄³⁻) entering surface waters promote eutrophication. Recent research showed that floating treatment wetlands combined with slow-release lanthanum composites [...] Read more.

Nutrient runoff is a major water quality issue affecting water resources. Excess nutrients such as nitrate (NO₃⁻) and phosphate (PO₄³⁻) entering surface waters promote eutrophication. Recent research showed that floating treatment wetlands combined with slow-release lanthanum composites deployed through airlift pumps can reduce NO₃⁻ and PO₄³⁻ concentrations, minimize algae and weeds, and increase dissolved oxygen concentrations. While water quality improves following this biological and chemical approach, questions remain about the toxicity and potential accumulation of lanthanum in lentic organisms. We addressed this concern by analyzing flesh and liver of fish exposed to the slow-release lanthanum following two years of treatment and compared results to fish harvested from a control, untreated pond. We also conducted an aquarium fish study that used higher lanthanum concentrations than those observed in the field. The field study confirmed that under the concentrations of lanthanum released to treat eutrophic ponds (109 µg L⁻¹), no adverse effects were observed in harvested fish. We also observed no significant differences between lanthanum-exposed and -unexposed fish (α = 0.05) in our controlled tank study. Given the laboratory tank lanthanum concentrations were approximately nine times higher (916 µg L⁻¹) than the observed field concentrations, we conclude the slow-release lanthanum composites used to treat eutrophic ponds are effective in improving water quality and do not lead to significant lanthanum accumulation in fish. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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13 pages, 3109 KiB  

Open AccessArticle

Application of Pb Isotopes and REY Patterns in Tracing Heavy Metals in Farmland Soils from the Upper-Middle Area of Yangtze River

by Yongqiang Ning, Bizheng Yang, Shaochen Yang, Jiaxin Ye, Junjie Li, Limin Ren, Zhifu Liu, Xiangyang Bi and Jinling Liu

Int. J. Environ. Res. Public Health 2023, 20(2), 966; https://doi.org/10.3390/ijerph20020966 - 05 Jan 2023

Cited by 2 | Viewed by 1248

Abstract

Farmland heavy metal pollution—caused by both human activity and natural processes—is a major global issue. In the current study, principal component analysis (PCA), cluster analysis (CA), rare earth elements and yttrium (REY) analysis, and isotope fingerprinting were combined to identify sources of heavy [...] Read more.

Farmland heavy metal pollution—caused by both human activity and natural processes—is a major global issue. In the current study, principal component analysis (PCA), cluster analysis (CA), rare earth elements and yttrium (REY) analysis, and isotope fingerprinting were combined to identify sources of heavy metal pollution in soil from different farmland types in the upper-middle area of the Yangtze River. The concentrations of Zn and Cu were found to be higher in the vegetable base and tea plantation soil compared with their concentrations in the orangery soil. On the other hand, greater accumulation of Cd and Pb was observed in the orangery soil versus the vegetable base and tea plantation soils. Influenced by the type of bedrock, REY was significantly enriched in the orangery soil and depleted in the vegetable base soil, as compared with the tea plantation soil. The Pb isotopic compositions of the tea plantation (1.173–1.193 for ²⁰⁶Pb/²⁰⁷Pb and 2.070–2.110 for ²⁰⁸Pb/²⁰⁶Pb) and vegetable base (1.181–1.217 for ²⁰⁶Pb/²⁰⁷Pb and 2.052–2.116 for ²⁰⁸Pb/²⁰⁶Pb) soils were comparable to those of coal combustion soil. The compositions of ²⁰⁶Pb/²⁰⁷Pb (1.149–1.170) and ²⁰⁸Pb/²⁰⁶Pb (2.121–2.143) in the orangery soil fell between those observed in soils obtained from coal combustion and ore smelting sites. Using the IsoSource model, the atmospheric Pb contributions of the vegetable base, tea plantation, and orangery soils were calculated to be 66.6%, 90.1%, and 82.0%, respectively, and the bedrock contributions of Pb were calculated to be 33.3%, 9.90%, and 18.1%, respectively. Based on the PCA, CA, and REY results, as well as the Pb isotope model, it appears that heavy metals in the orangery soil may be derived from atmospheric deposition and bedrock weathering, while heavy metals in the vegetable base and tea plantation soils may be derived from mining and the use of fertilizer. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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16 pages, 5536 KiB  

Open AccessArticle

Enhancing Mechanisms of the Plant Growth-Promoting Bacterial Strain Brevibacillus sp. SR-9 on Cadmium Enrichment in Sweet Sorghum by Metagenomic and Transcriptomic Analysis

by Xiao-Qi Li, Yong-Qi Liu, Ying-Jun Li, Hui Han, Hao Zhang, Ming-Fei Ji and Zhao-Jin Chen

Int. J. Environ. Res. Public Health 2022, 19(23), 16309; https://doi.org/10.3390/ijerph192316309 - 06 Dec 2022

Cited by 6 | Viewed by 1561

Abstract

To explore the mechanism by which the plant growth-promoting bacterium Brevibacillus sp. SR-9 improves sweet sorghum tolerance and enriches soil cadmium (Cd) under pot conditions, the effect of strain SR-9 inoculation on the microbial community of sorghum rhizosphere soil was analyzed by metagenomics. [...] Read more.

To explore the mechanism by which the plant growth-promoting bacterium Brevibacillus sp. SR-9 improves sweet sorghum tolerance and enriches soil cadmium (Cd) under pot conditions, the effect of strain SR-9 inoculation on the microbial community of sorghum rhizosphere soil was analyzed by metagenomics. Gene expression in sweet sorghum roots was analyzed using transcriptomics. The results showed that strain SR-9 promoted the growth of sweet sorghum and improved the absorption and enrichment of Cd in the plants. Compared with the uninoculated treatment, the aboveground part and root dry weight in strain SR-9 inoculated with sorghum increased by 21.09% and 17.37%, respectively, and the accumulation of Cd increased by 135% and 53.41%, respectively. High-throughput sequencing showed that strain SR-9 inoculation altered the rhizosphere bacterial community, significantly increasing the relative abundance of Actinobacteria and Firmicutes. Metagenomic analysis showed that after inoculation with strain SR-9, the abundance of genes involved in amino acid transport metabolism, energy generation and conversion, and carbohydrate transport metabolism increased. KEGG functional classification showed that inoculation with strain SR-9 increased the abundance of genes involved in soil microbial metabolic pathways in the rhizosphere soil of sweet sorghum and the activity of soil bacteria. Transcriptome analysis identified 198 upregulated differentially expressed genes in sweet sorghum inoculated with strain SR-9, including those involved in genetic information processing, biological system, metabolism, environmental information processing, cellular process, and human disease. Most of the annotated differentially expressed genes were enriched in the metabolic category and were related to pathways such as signal transduction, carbohydrate metabolism, amino acid metabolism, and biosynthesis of other secondary metabolites. This study showed that plant growth-promoting bacteria can alter the rhizosphere bacterial community composition, increasing the activity of soil bacteria and upregulating gene expression in sweet sorghum roots. The findings enhance our understanding of the microbiological and botanical mechanisms by which plant growth-promoting bacterial inoculation improves the remediation of heavy metals by sorghum. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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13 pages, 2542 KiB  

Open AccessFeature PaperArticle

Immobilization of Pb and Zn in Contaminated Soil Using Alumina–Silica Nano-Amendments Synthesized from Coal Fly Ash

by Chang Lei, Hao Huang, Haoxin Ye, Zhiping Fu, Peipei Peng, Shaoqing Zhang and Laishou Long

Int. J. Environ. Res. Public Health 2022, 19(23), 16204; https://doi.org/10.3390/ijerph192316204 - 03 Dec 2022

Cited by 1 | Viewed by 1183

Abstract

To apply coal fly ash to the remediation of heavy-metal-contaminated soil, an alumina–silica nano-amendment (ASNA) was synthesized from coal fly ash and was used for the immobilization of lead and zinc in contaminated soil. The investigation on the synthesis of the ASNA shows [...] Read more.

To apply coal fly ash to the remediation of heavy-metal-contaminated soil, an alumina–silica nano-amendment (ASNA) was synthesized from coal fly ash and was used for the immobilization of lead and zinc in contaminated soil. The investigation on the synthesis of the ASNA shows that the ASNA can be obtained under a roasting temperature of 700 °C, a ratio of alkali to coal fly ash of 1.2:1, and a molar ratio of silicon to aluminum of 1:1. The ASNA could increase the soil pH and cation exchange capacity (CEC) and decrease the bioavailability of Pb and Zn. When the ASNA addition increased from 0 to 2%, the bioavailability (extracted by CaCl₂) of Pb and Zn decreased by 47% and 72%, respectively. Moreover, the addition of the ASNA facilitated the transformation of Pb from a reducible fraction to oxidizable and residual fractions and Zn from an exchangeable fraction to a residual fraction. The correlation analysis and cluster analysis verify that the ASNA modulates the chemical speciation of heavy metals by increasing the soil’s CEC and pH, thereby immobilizing heavy metals. It is expected that this study can provide a new method for the remediation of Pb- and Zn-contaminated soil. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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20 pages, 8455 KiB  

Open AccessArticle

Water-Holding Properties of Clinoptilolite/Sodium Polyacrylate-Modified Compacted Clay Cover of Tailing Pond

by Xin-Po Sun, Ze-Hao Ding, Yu-Zhang Bi and Xin-Yi Wang

Int. J. Environ. Res. Public Health 2022, 19(23), 15554; https://doi.org/10.3390/ijerph192315554 - 23 Nov 2022

Cited by 1 | Viewed by 1676

Abstract

Clinoptilolite and sodium polyacrylate (Na-PAA) were used as water-retaining agents to improve the water-holding capacity of compacted clay cover (CCC). The optimum moisture content and Atterberg limits of the CCC modified by clinoptilolite and Na-PAA were studied. The soil–water characteristic curve (SWCC) of [...] Read more.

Clinoptilolite and sodium polyacrylate (Na-PAA) were used as water-retaining agents to improve the water-holding capacity of compacted clay cover (CCC). The optimum moisture content and Atterberg limits of the CCC modified by clinoptilolite and Na-PAA were studied. The soil–water characteristic curve (SWCC) of the CCC modified by clinoptilolite and Na-PAA was studied. The mesostructure of the CCC was analyzed by polarized light microscopy. The test results show that: (1) the optimum moisture content and liquid limit of the CCC modified by clinoptilolite and Na-PAA increased, while the maximum dry density decreased; (2) the SWCC of the CCC modified by clinoptilolite and Na-PAA shifts to the upper right, and the volume moisture content of modified CCC is higher than that of unmodified CCC under the same matrix suction; (3) compared with the unmodified CCC, the air-entry value (AEV) of the clinoptilolite-modified CCC increased by 65.18% at most, and the AEV of the further modified CCC with Na-PAA in-creased by about two times; and (4) the flocculation structure and porosity of modified CCC decreased, and the porosity was distributed uniformly. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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24 pages, 2783 KiB  

Open AccessArticle

Assessing a Large-Scale Sequential In Situ Chloroethene Bioremediation System Using Compound-Specific Isotope Analysis (CSIA) and Geochemical Modeling

by Giulia Casiraghi, Daniele Pedretti, Giovanni Pietro Beretta, Marco Masetti and Simone Varisco

Pollutants 2022, 2(4), 462-485; https://doi.org/10.3390/pollutants2040031 - 11 Nov 2022

Viewed by 1327

Abstract

Compound-specific isotopic analysis (CSIA) and geochemical modeling were applied to evaluate the effectiveness of an 800 m-long sequential in situ bioremediation (ISB) system in Northern Italy. The system was created for the clean-up of a polluted aquifer affected by chloroethenes. A hydraulically upgradient [...] Read more.

Compound-specific isotopic analysis (CSIA) and geochemical modeling were applied to evaluate the effectiveness of an 800 m-long sequential in situ bioremediation (ISB) system in Northern Italy. The system was created for the clean-up of a polluted aquifer affected by chloroethenes. A hydraulically upgradient anaerobic (AN)-biobarrier-stimulated reductive dichlorination (RD) of higher chloroethenes (PCE, TCE) and a downgradient aerobic (AE)-biobarrier-stimulated oxidation (OX) of lower chloroethenes (DCE, VC) were proposed. Carbon CSIA and concentration data were collected for PCE, TCE, cis-DCE and VC and interpreted using a reactive transport model that was able to simulate isotopic fractionation. The analysis suggested that the combination of CSIA and modeling was critical to evaluate the efficiency of sequential ISBs for the remediation of chloroethenes. It was found that the sequential ISB could reduce the PCE, TCE and cis-DCE concentrations by >99% and VC concentrations by >84% along the flow path. First-order RD degradation rate constants ($k_{RD}$) increased by 30 times (from $k_{RD}$= 0.2–0.3 y⁻¹ up to $k_{RD}$ = 6.5 y⁻¹) downgradient of the AN barrier. For cis-DCE and VC, the AE barrier had a fundamental role to enhance OX. First-order OX degradation rate constants ($k_{OX}$) ranged between $k_{OX}$= 0.7–155 y⁻¹ for cis-DCE and $k_{OX }$= 1.7–12.6 y⁻¹ for VC. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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18 pages, 1879 KiB  

Open AccessArticle

Fate of Saxitoxins in Lake Water: Preliminary Testing of Degradation by Microbes and Sunlight

by Niels O. G. Jørgensen, Raju Podduturi, Charlotte Frydenlund Michelsen, Thea Jepsen and Munique de Almeida Bispo Moraes

Water 2022, 14(21), 3556; https://doi.org/10.3390/w14213556 - 05 Nov 2022

Cited by 4 | Viewed by 1902

Abstract

The cyanobacterial toxin saxitoxin (STX) is mainly associated with the blooms of marine dinoflagellates, but it is also produced by several species of freshwater cyanobacteria. So far, the degradation of STX has only been demonstrated by physicochemical treatments, but in this study, we [...] Read more.

The cyanobacterial toxin saxitoxin (STX) is mainly associated with the blooms of marine dinoflagellates, but it is also produced by several species of freshwater cyanobacteria. So far, the degradation of STX has only been demonstrated by physicochemical treatments, but in this study, we demonstrated that natural factors, such as bacterioplankton and sunlight, had the capacity for degrading STX in the eutrophic Lake Arresø, Denmark. Natural lake bacterioplankton could reduce STX concentrations by 41–59%. A similar reduction was shown for four saxitoxin analogs. The exposure of the lake water to natural sunlight or simulated sunlight also reduced both intracellular and extracellular, dissolved STX. During 4–8 h exposure, natural sunlight reduced intracellular STX by 38–52% but increased extracellular, dissolved STX by 7–29%. Corresponding values for simulated sunlight were a reduction in intracellular STX by 16–45% and increased levels of extracellular STX by 10–33%. In particle-free lake water, the two types of sunlight reduced ambient, dissolved STX by 13–17%. The light exposure was observed to damage >94% of the sxtA gene involved in STX synthesis. This study demonstrated that lake water bacterioplankton and sunlight can modify STX by degradation and cell destruction, and that the biosynthesis of STX may be inhibited by exposure to sunlight. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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13 pages, 3099 KiB  

Open AccessArticle

The Removal of Cr(VI) from Aqueous Solutions with Corn Stalk Biochar

by Wenling Yang, Gao Lei, Shujing Quan, Longfei Zhang, Baitao Wang, Hong Hu, Liangliang Li, Huan Ma, Chaohui Yin, Fei Feng and Yanyan Jing

Int. J. Environ. Res. Public Health 2022, 19(21), 14188; https://doi.org/10.3390/ijerph192114188 - 30 Oct 2022

Cited by 5 | Viewed by 1375

Abstract

The discharge of wastewater containing hexavalent chromium (Cr(VI)) into the environment is very harmful to living things. Therefore, before effluent that contains Cr(VI) can be discharged into the environment, this toxin should be removed from the contaminated water. In this study, corn stalk [...] Read more.

The discharge of wastewater containing hexavalent chromium (Cr(VI)) into the environment is very harmful to living things. Therefore, before effluent that contains Cr(VI) can be discharged into the environment, this toxin should be removed from the contaminated water. In this study, corn stalk biochar was investigated to evaluate the Cr(VI) removal efficiency from an aqueous solution. The effects of pH (2–10), biochar concentration (0.5 to 10 g/L), Cr(VI) concentration (10–500 mg/L), and contact time (10–1440 min) were studied. The actual experimental value of the Cr(VI) removal efficiency was 28.67%, largely consistent with the predicted model value of 29.31%, under the optimal conditions of a Cr(VI) concentration of 60 g/L, pH 4, contact time of 270 min, and a biochar concentration of 4.5 g/L. A significant interaction between the Cr(VI) concentration and pH was observed, along with significance in the interaction between Cr(VI) concentration and biochar concentration, which had a greater impact on the removal of Cr(VI). Biosorption onto corn stalk biochar is an affordable and economical adsorption process to treat wastewater contaminated with Cr(VI). The aim of this study is to provide data to serve as a basis for future studies on the use of raw agricultural waste to remove Cr(VI). Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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10 pages, 2480 KiB  

Open AccessArticle

Efficiency Determination and Mechanism Investigation of Autotrophic Denitrification Strain F1 to Promote Low-Carbon Development

by Fang-Kai Qin, Si-Zhuo Wan, Bing-Yin Liu, Ru Wang and Ping Zheng

Water 2022, 14(21), 3353; https://doi.org/10.3390/w14213353 - 22 Oct 2022

Viewed by 1319

Abstract

Shewanella sp. strain F1, isolated from a lab-scale Fe(II)−dependent anaerobic denitrifying reactor, could reduce nitrate by oxidizing Fe(II). Its nitrate reduction rate and Fe(II) oxidation rate were 0.48 mg/(L·h) and 5.05 mg/(L·h) at OD₆₀₀ of 0.4786 with a five-fold diluent. Shewanella sp. [...] Read more.

Shewanella sp. strain F1, isolated from a lab-scale Fe(II)−dependent anaerobic denitrifying reactor, could reduce nitrate by oxidizing Fe(II). Its nitrate reduction rate and Fe(II) oxidation rate were 0.48 mg/(L·h) and 5.05 mg/(L·h) at OD₆₀₀ of 0.4786 with a five-fold diluent. Shewanella sp. was popular in Fe(III) reduction. Fewer studies about its ability for Fe(II) oxidation are available. The low pH was determined to be the switch for Shewanella sp. strain F1 to perform Fe(III) reduction or Fe(II) oxidation. Even under a low pH, the produced Fe(III) precipitated around cells from iron encrustation. By observation of the morphologies of strain F1, two corresponding microbial mechanisms were proposed. One was named Cyc 2−based Fe(II)-dependent denitrification, in which Fe(II) was oxidized by Cyc 2 in the outer cell membrane, and the produced Fe(III) precipitated on the cell wall surface to form tiled iron encrustation. The other was named Cyc 1−based Fe(II)−dependent denitrification, in which Fe(II) was oxidized on the existing iron precipitation on the cell wall surface to form towery iron encrustation, and the electron was transported to Cyc 1 in the periplasm. The efficiency determination and mechanism investigation of strain F1 will promote the development of autotrophic denitrification technology and meet the requirement of a low−carbon policy. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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18 pages, 2260 KiB  

Open AccessArticle

Differentiation between Impacted and Unimpacted Microbial Communities of a Nitrogen Contaminated Aquifer

by Justin G. Morrissy, Suzie M. Reichman, Matthew J. Currell, Aravind Surapaneni, Mallavarapu Megharaj, Nicholas D. Crosbie, Daniel Hirth, Simon Aquilina, William Rajendram and Andrew S. Ball

Environments 2022, 9(10), 128; https://doi.org/10.3390/environments9100128 - 09 Oct 2022

Viewed by 3283

Abstract

Nitrogen contamination is ubiquitous across the globe; as a result of this, the need to understand and predict the extent and effects of nitrogen contamination on microbial ecosystems is increasingly important. This paper utilises a dataset that provides a rare opportunity to observe [...] Read more.

Nitrogen contamination is ubiquitous across the globe; as a result of this, the need to understand and predict the extent and effects of nitrogen contamination on microbial ecosystems is increasingly important. This paper utilises a dataset that provides a rare opportunity to observe varying contamination conditions in a single aquifer and understand the differences between potential background bores and two different types of contamination spread across the other bores. Using physicochemical and microbiological community analysis, this paper aims to determine the impacts of the two contaminants, nitrate and ammonia, on the microbial communities and the differences between polluted and physicochemical background bores. Total nitrogen (N) varied by a factor of over 2000 between bores, ranging from 0.07 to 155 mg L⁻¹. Nitrate (NO₃⁻) concentrations ranged from 150 to <0.01 mg L⁻¹; ammonium (NH₄⁺) concentrations ranged from 26 to <0.1 mg L⁻¹. MANOVA analysis confirmed an overall significant relationship (p = 0.0052) between N variables and the physicochemical data (or status) of the three areas of contamination dubbed ‘contamination zones’. The contamination zones were defined by no known presence of contamination in the uncontaminated bores, the presence of NO₃⁻ contamination and the presence of NO₃⁻ and NH₄⁺ contamination. PERMANOVA analysis confirmed that there was an overall significant difference in the microbial communities between the three contamination zones (p = 0.0002); however, the presence of NH₄⁺ had a significant effect (p = 0.0012). In general, the nitrate-contaminated bores showed a decrease in the abundance of individual OTUs. We further confirmed that NH₄⁺ contamination had a significant relationship with an increased percentage of abundance occupied by the Planctomycetota phylum (specifically the Candidatus Brocadia genus). It was found that one of the two background bores (BS-004) was likely also representative of natural microbial background, and another (BS-002) showed characteristics that may be representative of past or intermittent contamination. This paper demonstrates a possible way to determine the microbial background and discusses the potential uses for this information. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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15 pages, 860 KiB  

Open AccessArticle

Zeolite-Assisted Immobilization and Health Risks of Potentially Toxic Elements in Wastewater-Irrigated Soil under Brinjal (Solanum melongena) Cultivation

by Zia Ur Rahman Farooqi, Iftikhar Ahmad, Ayesha Abdul Qadir, Ghulam Murtaza, Sana Rafiq, Aftab Jamal, Nukshab Zeeshan, Behzad Murtaza, Wasim Javed, Emanuele Radicetti and Roberto Mancinelli

Agronomy 2022, 12(10), 2433; https://doi.org/10.3390/agronomy12102433 - 08 Oct 2022

Cited by 5 | Viewed by 1642

Abstract

Application of wastewater to agricultural soils not only enhances economic benefits but is also considered as a safe disposal option by the administrators. Worldwide, peri-urban horticulture is a common practice for growing vegetables. When agricultural soils are irrigated with wastewater, numerous potentially toxic [...] Read more.

Application of wastewater to agricultural soils not only enhances economic benefits but is also considered as a safe disposal option by the administrators. Worldwide, peri-urban horticulture is a common practice for growing vegetables. When agricultural soils are irrigated with wastewater, numerous potentially toxic elements (PTEs) contained therein are bioaccumulated and pose health risks. The presented study aimed to reveal the PTEs, i.e., copper (Cu), cadmium (Cd), nickel (Ni) and lead (Pb) concentration in the agricultural soils irrigated with wastewater for longer times. Zeolite, a natural mineral was used to immobilize these in contaminated soils to reduce its availability to brinjal (Solanum melongena L.). During a pot study, zeolite was applied at four different levels, i.e., 0.25, 0.50, 1.00 and 2.00% in contaminated soil, keeping one control. The results revealed that growth as well as biochemical and physiological characters were found best with treatment receiving zeolite at 2.00%. In edible parts (fruit), PTE contents were found lowest in the same treatment. Relative to the control, ~121, 87, 120 and 140% less DTPA-extracted Cu, Cd, Ni and Pb in soil was found with this treatment. Based on the results, it was revealed that zeolite effectively immobilized Cu, Cd, Ni and Pb in the soil. Although all the applied levels of zeolite had positive potential to immobilize PTEs in wastewater-contaminated soil, zeolite applied at 2.00% proved most effective. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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13 pages, 1082 KiB  

Open AccessArticle

Evaluation of the Use of Lime and Nanosilica for the Improvement of Clay Soil Structure and Degradation of Hydrocarbons

by Adriana Muente, Isabel Cipriani-Ávila, Karina García-Villacís, Verónica Pinos-Veléz, Daniel Hidalgo-Lasso, Pablo Ruíz and Verónica Luna

Pollutants 2022, 2(4), 422-434; https://doi.org/10.3390/pollutants2040028 - 01 Oct 2022

Cited by 2 | Viewed by 1730

Abstract

Soil structure is an important key in the bioremediation process; for instance, clay soils tend to have high absorption of pollutants and low rates of bioremediation due to their high plasticity and oxygen restrictions. This work assesses seven different treatments for contaminated clay [...] Read more.

Soil structure is an important key in the bioremediation process; for instance, clay soils tend to have high absorption of pollutants and low rates of bioremediation due to their high plasticity and oxygen restrictions. This work assesses seven different treatments for contaminated clay soil using lime, silica nanoparticles, and both components in combination. After a three-month treatment, the variation of the soil granulometry, pH, porosity, cation exchange capacity (CEC), humidity, organic matter, respirometry, and humic acids were measured in order to evaluate the improvements regarding soil structure. Furthermore, total petroleum hydrocarbon (TPH), polycyclic aromatic hydrocarbons (PAHs) and heavy metals were monitored before and after the treatments. The combined treatment using lime and nanosilica presented the best results, reducing the percentage of clays from 61% to 5% and showing a relationship between improved of soil structure and the reduction of pollutants, with a 35% removal for TPHs being the highest obtained with the seven treatments. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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15 pages, 1348 KiB  

Open AccessArticle

Effects of Sound Wave and Water Management on Growth and Cd Accumulation by Water Spinach (Ipomoea aquatica Forsk.)

by Su Wang, Yifan Shao, Jinsheng Duan, Huaidong He and Qingqing Xiao

Agronomy 2022, 12(10), 2257; https://doi.org/10.3390/agronomy12102257 - 21 Sep 2022

Cited by 4 | Viewed by 2097

Abstract

Vegetable contamination by cadmium (Cd) is of great concern. Water spinach (Ipomoea aquatica) is a common leafy vegetable in many countries and has a strong ability to accumulate Cd. The work was conducted to study the effects of sound wave, water [...] Read more.

Vegetable contamination by cadmium (Cd) is of great concern. Water spinach (Ipomoea aquatica) is a common leafy vegetable in many countries and has a strong ability to accumulate Cd. The work was conducted to study the effects of sound wave, water management, and their combination on Cd accumulation and growth of water spinach, using the following three experiments: a hydroponic trial with the treatment of a plant acoustic frequency technology (PAFT) generator in test sheds, a hydroponic trial with three music treatments (electronic music (EM), rock music (RM), and classical music (CM)) in artificial climate boxes, and a soil pot trial with treatments of PAFT and EM under non-flooded and flooded conditions. The results showed that the hydroponic treatments of PAFT and EM significantly reduced the Cd concentrations in roots and shoots (edible parts) of water spinach by 22.01–36.50% compared with the control, possibly due to sound waves decreasing the root tip number per unit area and increasing average root diameter, root surface area, and total root length. Sound wave treatments clearly enhanced water spinach biomass by 28.27–38.32% in the hydroponic experiments. In the soil experiment, the flooded treatment significantly reduced the Cd concentrations in roots and shoots by 43.75–63.75%, compared with the non-flooded treatment. The Cd decrease and the biomass increase were further driven by the PAFT supplement under the flooding condition, likely related to the alteration in root porosity, rates of radial oxygen loss, extractable soil Cd, soil Eh, and soil pH. Our results indicate that the co-application of plant acoustic frequency technology and flooded management may be an effective approach to reduce Cd accumulation in water spinach. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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20 pages, 2109 KiB  

Open AccessArticle

Pyrite-Based Autotrophic Denitrifying Microorganisms Derived from Paddy Soils: Effects of Organic Co-Substrate Addition

by Baokun Xu, Xiaoxia Yang, Yalong Li, Kejun Yang, Yujiang Xiong and Niannian Yuan

Int. J. Environ. Res. Public Health 2022, 19(18), 11763; https://doi.org/10.3390/ijerph191811763 - 18 Sep 2022

Cited by 3 | Viewed by 1622

Abstract

The presence of organic co-substrate in groundwater and soils is inevitable, and much remains to be learned about the roles of organic co-substrates during pyrite-based denitrification. Herein, an organic co-substrate (acetate) was added to a pyrite-based denitrification system, and the impact of the [...] Read more.

The presence of organic co-substrate in groundwater and soils is inevitable, and much remains to be learned about the roles of organic co-substrates during pyrite-based denitrification. Herein, an organic co-substrate (acetate) was added to a pyrite-based denitrification system, and the impact of the organic co-substrate on the performance and bacterial community of pyrite-based denitrification processes was evaluated. The addition of organic co-substrate at concentrations higher than 48 mg L⁻¹ inhibited pyrite-based autotrophic denitrification, as no sulfate was produced in treatments with high organic co-substrate addition. In contrast, both competition and promotion effects on pyrite-based autotrophic denitrification occurred with organic co-substrate addition at concentrations of 24 and 48 mg L⁻¹. The subsequent validation experiments suggested that competition had a greater influence than promotion when organic co-substrate was added, even at a low concentration. Thiobacillus, a common chemolithoautotrophic sulfur-oxidizing denitrifier, dominated the system with a relative abundance of 13.04% when pyrite served as the sole electron donor. With the addition of organic co-substrate, Pseudomonas became the dominant genus, with 60.82%, 61.34%, 70.37%, 73.44%, and 35.46% abundance at organic matter concentrations of 24, 48, 120, 240, and 480 mg L⁻¹, respectively. These findings provide an important theoretical basis for the cultivation of pyrite-based autotrophic denitrifying microorganisms for nitrate removal in soils and groundwater. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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29 pages, 3970 KiB  

Open AccessReview

The Potential of Constructed Wetland Systems and Photodegradation Processes for the Removal of Emerging Contaminants—A Review

by Marta Sánchez, Isabel Ruiz and Manuel Soto

Environments 2022, 9(9), 116; https://doi.org/10.3390/environments9090116 - 06 Sep 2022

Cited by 15 | Viewed by 5277

Abstract

The presence of emerging organic contaminants (EOCs) in the environment is increasing and requires the development of technologies for their effective removal. Therefore, a literature review on the behavior of EOCs during municipal wastewater treatment, both in major treatment systems and particularly in [...] Read more.

The presence of emerging organic contaminants (EOCs) in the environment is increasing and requires the development of technologies for their effective removal. Therefore, a literature review on the behavior of EOCs during municipal wastewater treatment, both in major treatment systems and particularly in constructed wetlands (CWs), was carried out. The study also reviewed the behavior of EOCs in anaerobic digesters (ADs) and advanced oxidation processes, particularly in TiO₂-based photocatalysis, which are being proposed as promising pre- and post-treatments for combination with CW. The following ten compounds were screened: acetaminophen (ACE), ofloxacin (OFL), caffeine (CAF), carbamazepine (CBZ), ketoprofen (KET), ibuprofen (IBU), diclofenac (DCL), clofibric acid (ACB), bisphenol A (BPA), and sotalol (SOT). The degradation pathways of the selected EOCs are largely influenced by their physicochemical and biochemical properties. Sorption and biodegradation are the main elimination mechanisms found in AD and CW treatment systems, where the combination of anaerobic and aerobic environments improves the elimination efficiency of EOCs. However, various contaminants appear recalcitrant. In this sense, in combination with CWs, TiO₂-based photocatalysis emerges as a promising post-treatment for advanced EOC removal from wastewater. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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18 pages, 4026 KiB  

Open AccessArticle

Synthesis of Functionalized Carboxylated Graphene Oxide for the Remediation of Pb and Cr Contaminated Water

by Sana Farooq, Humera Aziz, Shafaqat Ali, Ghulam Murtaza, Muhammad Rizwan, Muhammad Hamzah Saleem, Shahid Mahboob, Khalid A. Al-Ghanim, Mian N. Riaz and Behzad Murtaza

Int. J. Environ. Res. Public Health 2022, 19(17), 10610; https://doi.org/10.3390/ijerph191710610 - 25 Aug 2022

Cited by 4 | Viewed by 2511

Abstract

With the growing scarcity of water, the remediation of water polluted with heavy metals is the need of hour. The present research work is aimed to address this problem by adsorbing heavy metals ions (Pb (II) and Cr (VI)) on modified graphene oxide [...] Read more.

With the growing scarcity of water, the remediation of water polluted with heavy metals is the need of hour. The present research work is aimed to address this problem by adsorbing heavy metals ions (Pb (II) and Cr (VI)) on modified graphene oxide having an excess of carboxylic acid groups. For this, graphene oxide (GO) was modified with chloroacetic acid to produce carboxylated graphene oxide (GO-COOH). The successful synthesis of graphene oxide and its modification has been confirmed using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray Diffraction (XRD), Scanning electron microscopy (SEM), Energy Dispersive X-ray Analysis (EDX) and Transmission electron microscopy (TEM). The increase in surface area of graphene oxide after treatment with chloroacetic acid characterized by BET indicated its successful modification. A batch experiment was conducted to optimize the different factors affecting adsorption of both heavy metals on GO-COOH. After functionalization, we achieved maximum adsorption capacities of 588.23 mg g⁻¹ and 370.37 mg g⁻¹ for Pb and Cr, respectively, by GO-COOH which were high compared to the previously reported adsorbents of this kind. The Langmuir model (R² = 0.998) and Pseudo-second-order kinetic model (R² = 0.999) confirmed the monolayer adsorption of Pb and Cr on GO-COOH and the chemisorption as the dominant process governing adsorption mechanism. The present work shows that the carboxylation of GO can enhance its adsorption capacity efficiently and may be applicable for the treatment of wastewater. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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33 pages, 19752 KiB  

Open AccessArticle

Prediction of Water-Blocking Capability of Water-Seepage-Resistance Strata Based on AHP-Fuzzy Comprehensive Evaluation Method—A Case Study

by Liqiang Ma, Yujun Xu, Ichhuy Ngo, Yangyang Wang, Jiangtao Zhai and Lixiao Hou

Water 2022, 14(16), 2517; https://doi.org/10.3390/w14162517 - 15 Aug 2022

Cited by 16 | Viewed by 1965

Abstract

Coal mining under the aquifer in Northwest China has brought a series of ecological problems, such as the decline of groundwater levels and the death of surface vegetation. The study of the impermeability of rock strata between coal seams and the overlying aquifers [...] Read more.

Coal mining under the aquifer in Northwest China has brought a series of ecological problems, such as the decline of groundwater levels and the death of surface vegetation. The study of the impermeability of rock strata between coal seams and the overlying aquifers is of great significance to solve these problems and realize water-preserving coal mining (WPCM). Based on mining-induced overburden damage and permeability deterioration, the concept of the “three seepage zones” of overburden is proposed, namely the pipe flow zone, water seepage zone and nominal water-seepage-resistance zone (NWSRZ). Meanwhile, the concept of water-seepage-resistance strata (WSRS) is put forward from the aspects of initial permeability, structural strength, swelling and the stratigraphic structure of the overlying strata. AHP-fuzzy comprehensive evaluation (AHPF) is employed to construct a model to evaluate the water-blocking capacity (WBC) of the WSRS. The model includes three secondary factors and nine tertiary indicators, and the weights and membership functions of the indicators are determined. Subsequently, the model is generalized and applied to the Yu-Shen mining area. The membership degrees are spatially visualized by means of thematic maps. The comprehensive evaluation values Φ of the WBCWSRS of 400 boreholes in the mining area under backfill mining, narrow strip mining, slice mining and longwall cave mining are calculated. Then, the Kriging method is employed to plot the zoning maps of Φ under four different mining methods. In view of different grades of WBCWSRS, three corresponding countermeasures, i.e., mining methods optimization, curtain grouting and underground reservoir construction, are put forward. The fluid–solid coupling embedded in FALC^3D software is employed to establish a numerical calculation model to simulate the water table fluctuation of the underground aquifer under the four mining methods, and the reliability of the model is verified indirectly. In this paper, mathematical theory is combined with WPCM to develop an evaluation model of WBCWSRS, which provides a reference for the coordinated development of coal extraction and water resource preservation in arid and semi-arid mining areas. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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15 pages, 2552 KiB  

Open AccessArticle

How Does Adjacent Land Use Influence Sediment Metals Content and Potential Ecological Risk in the Hongze Lake Wetland?

by Yanhui Guo, Yongfeng Xu, Chenming Zhu, Pingping Li, Yongli Zhu and Jiangang Han

Int. J. Environ. Res. Public Health 2022, 19(16), 10079; https://doi.org/10.3390/ijerph191610079 - 15 Aug 2022

Cited by 2 | Viewed by 1317

Abstract

Metal pollution in lake wetlands has become increasingly serious in China and worldwide due to the rapid growth of urbanization and agricultural activities. However, comprehensive assessments of metal pollution in lake wetland sediments that are associated with land use change have been limited [...] Read more.

Metal pollution in lake wetlands has become increasingly serious in China and worldwide due to the rapid growth of urbanization and agricultural activities. However, comprehensive assessments of metal pollution in lake wetland sediments that are associated with land use change have been limited from an international perspective. Metal concentrations (As, Cd, Cr, Cu, Hg, Mn, Pb, and Zn) were measured in the surface soils and surrounding sediments of five land use types in the eastern Hongze Lake wetlands, including Farmland (FL), Culture Ponds (CP), Reed Land (RL), Poplar Forests (PF), and Willow Forests (WF). The metal pollution status was assessed using the geo-accumulation index and the potential ecological risk index; The results showed that the average concentrations of As, Cd, Mn, and Zn in the surface soils and As, Cd, Cu, and Zn in the sediments, exceeded the background values of Jiangsu Province, China. The FL soils and surrounding sediments were moderately contaminated with As, whereas the sediments surrounding the CP were uncontaminated to moderately contaminated with Cd. Metal pollution in both soils and sediments was greater on farmland than on other types of land use. Furthermore, there were significant positive correlations between the values of the soil risk index and the values of the surrounding sediment risk index. Correlation analysis (CA) and principal component analysis (PCA) found that metals may be derived from agricultural activities such as the application of chemical and organic fertilizers, as well as domestic sewage, industrial wastewater, and geological anomalies. These findings shed new light on the quantitative impacts of adjacent land use practices on sediment metal pollution and provide a scientific foundation for wetland management decision-making. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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12 pages, 792 KiB  

Open AccessArticle

Removal of Zn²⁺ from Aqueous Solution Using Biomass Ash and Its Modified Product as Biosorbent

by Lei Xu, Xiangyu Xing and Jianbiao Peng

Int. J. Environ. Res. Public Health 2022, 19(15), 9006; https://doi.org/10.3390/ijerph19159006 - 24 Jul 2022

Cited by 1 | Viewed by 1745

Abstract

To study the removal effect of bottom ash of biomass power plants and its modified products on zinc (Zn²⁺) in aqueous solution, a series of indoor experiments is carried out. The aim of this work is to explore a method to [...] Read more.

To study the removal effect of bottom ash of biomass power plants and its modified products on zinc (Zn²⁺) in aqueous solution, a series of indoor experiments is carried out. The aim of this work is to explore a method to improve the ability of biomass ash to remove Zn²⁺ from aqueous solution and obtain its adsorption characteristics of Zn²⁺ in aqueous solution; on this basis, the feasibility of its application in the treatment of Zn²⁺-contaminated wastewater is analyzed. The mesoporous siliceous material is used to modify the biomass, and the modified material is functionalized with 3-aminopropyltriethoxysilane. The results show that the specific surface area of modified biomass ash is nine times that of the material before modification. The adsorption capacity of Zn²⁺ on the material increases with the increase of pH, and pH 6 is the optimum pH to remove Zn²⁺ from the aqueous solution. The Langmuir model and Freundlich model can show better fits for biomass ash and the modified material, respectively. Thermodynamic analysis results show that the adsorption of Zn²⁺ is spontaneous and endothermic in nature. The adsorption of Zn²⁺ onto biomass and modified biomass ash follow pseudo-first-order and pseudo-second-order kinetics, respectively. Full article

(This article belongs to the Topic Soil and Water Pollution Process and Remediation Technologies)

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