Toxics

Research

12 pages, 6614 KiB

Open AccessArticle

Screening of Profitable Chrysanthemums for the Phytoremediation of Cadmium-Contaminated Soils

by Xinzhe Lu, Yanfang Chen, Jinqiu Song, Jiayu Bao, Chunzheng Dai, Rui Sun, Jiacheng Liu, Chenjiang Jin, Nanchong Zhong, Chunlei Huang and Kokyo Oh

Toxics 2025, 13(5), 360; https://doi.org/10.3390/toxics13050360 (registering DOI) - 30 Apr 2025

Abstract

To explore the phytoremediation effect of ornamental chrysanthemums on cadmium (Cd)-contaminated farmland soil, a 2-year field trial was conducted on 23 chrysanthemum cultivars in Cd-contaminated soil in Zhejiang Province, China. The biomass yields, Cd content of the plants, Cd enrichment coefficient, and remediation [...] Read more.

To explore the phytoremediation effect of ornamental chrysanthemums on cadmium (Cd)-contaminated farmland soil, a 2-year field trial was conducted on 23 chrysanthemum cultivars in Cd-contaminated soil in Zhejiang Province, China. The biomass yields, Cd content of the plants, Cd enrichment coefficient, and remediation efficiency were evaluated. The aboveground biomass of the tested chrysanthemums was 67.10–166.08 g/plant, the aboveground Cd content was 1.97–5.92 mg kg⁻¹, and the Cd enrichment coefficient was 2.98–9.84. In a screening test of twenty-three chrysanthemum cultivars, six cultivars, such as marigolds, were characterized by high cadmium accumulation, with the average cadmium accumulation of chrysanthemums exceeding 0.6 mg per plant, and the remediation of rhizosphere-contaminated soils took only 4–5 years. Fourteen chrysanthemum cultivars have good multiple-cropping characteristics, and five multiple-cropping chrysanthemum cultivars, such as QX-yz, have high heavy metal tolerance. The multiple-cropping JL-yg cultivars with higher Cd accumulation could be recommended for the remediation of Cd-contaminated farmland. The application of bamboo vinegar to the chrysanthemum rhizosphere effectively promoted Cd absorption. After estimating the economic benefits of artificially planting five dominant varieties of chrysanthemums for polluted farmland remediation, it is concluded that the annual income of a worker can be slightly higher than the average annual income level of local residents. Full article

(This article belongs to the Special Issue Safe Utilization and Ecological Restoration of Heavy Metal Polluted Farmland)

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16 pages, 2645 KiB

Open AccessArticle

Source Apportionment of Potentially Toxic Elements in Agricultural Soils of Yingtan City, Jiangxi Province, China: A Principal Component Analysis–Positive Matrix Factorization Method

by Shaoting Chen, Hongmei Wang and Ruiming Han

Toxics 2025, 13(4), 267; https://doi.org/10.3390/toxics13040267 - 31 Mar 2025

Viewed by 175

Abstract

The increase in the concentration of potentially toxic elements in farmland soil attracts more and more attention. To identify the sources of potentially toxic elements in agricultural soils, 148 soil samples in Yingtan were selected as a case study, potentially toxic elements levels [...] Read more.

The increase in the concentration of potentially toxic elements in farmland soil attracts more and more attention. To identify the sources of potentially toxic elements in agricultural soils, 148 soil samples in Yingtan were selected as a case study, potentially toxic elements levels were analyzed, and principal component analysis (PCA) and positive matrix factorization (PMF) were employed. The results indicate that the average of Zn (89.62 mg·kg⁻¹ d.w.), Cu (76.30 mg·kg⁻¹ d.w.), Pb (35.56 mg·kg⁻¹ d.w.), Mo (0.66 mg·kg⁻¹ d.w.), and Cd (0.59 mg·kg⁻¹ d.w.) exceed the corresponding soil background values of Jiangxi Province. Moreover, the high spatial coefficient of variation (above 1.00) for these elements suggests a significant influence from long-term external inputs. Among all of the elements above, the soil Cu and Cd concentrations indicate a relatively high pollution ranked by Igeo. Further analysis of sources apportioned by PCA and PMF implies that the potentially toxic elements input into agricultural soil may be attributed to mining activity, natural sources, smelting, and agricultural activity. This study implies that PCA-PMF combined with the field survey may be helpful tools for discerning the pollutants^’ sources, and it addresses a view that the increasing Cu and Cd levels in farmland is concerning, as it is associated with the historical use of mixed fertilizers and a lack of supervision. Full article

(This article belongs to the Special Issue Safe Utilization and Ecological Restoration of Heavy Metal Polluted Farmland)

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15 pages, 1316 KiB

Open AccessArticle

The Tolerance Differences of Two Industrial Hemp Varieties Under Lead (Pb) Stress

by Yanping Xu, Anuwat Kumpeangkeaw, Xia An, Xuan Chen, Yuan Zhang, Pin Lv, Qingying Zhang, Rong Guo, Qingqing Ji and Ming Yang

Toxics 2025, 13(2), 90; https://doi.org/10.3390/toxics13020090 - 24 Jan 2025

Viewed by 929

Abstract

Industrial hemp is a crop with a high tolerance and accumulation of lead (Pb). Improving the Pb tolerance and accumulation capacity of industrial hemp is of great scientific and practical importance. This study utilized a pot with soil contaminated with Pb to investigate [...] Read more.

Industrial hemp is a crop with a high tolerance and accumulation of lead (Pb). Improving the Pb tolerance and accumulation capacity of industrial hemp is of great scientific and practical importance. This study utilized a pot with soil contaminated with Pb to investigate the differences in Pb tolerance between two industrial hemp varieties, Yunma1 (YM) and Shaanxi Industrial Hemp (SM), under Pb stress. The results indicated that Pb mainly accumulates in the roots of YM and SM (70–80%), with YM having a higher Pb accumulation than SM. It is worth nothing that under high Pb concentration conditions (5000 mg/kg), the Pb accumulation capacity of YM is twice that of SM. Accumulation characteristics of Pb in different plant tissues followed the pattern: roots > stems > leaves > fibers > seeds. In YM, approximately 70% of the absorbed Pb was fixed in the roots and 30% was transported to the above-ground parts. In contrast, SM transported more than 50% of absorbed Pb by roots to the above-ground areas, causing some degree of damage to stems and leaves. Even when Pb concentrations exceed 4000 mg/kg, YM exhibits strong tolerance (tolerance index greater than 90%), with normal growth and no signs of toxicity. However, SM showed a tolerance level of < 50% at high Pb concentrations, with significant heavy metal toxicity symptoms in the above-ground areas. These results provide important information for the remediation of Pb contaminated soils in mining areas. Full article

(This article belongs to the Special Issue Safe Utilization and Ecological Restoration of Heavy Metal Polluted Farmland)

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21 pages, 2558 KiB

Open AccessArticle

Rice Husk as a Sustainable Amendment for Heavy Metal Immobilization in Contaminated Soils: A Pathway to Environmental Remediation

by Riccardo Cecire, Aleandro Diana, Agnese Giacomino, Ornella Abollino, Paolo Inaudi, Laura Favilli, Stefano Bertinetti, Simone Cavalera, Luisella Celi and Mery Malandrino

Toxics 2024, 12(11), 790; https://doi.org/10.3390/toxics12110790 - 29 Oct 2024

Cited by 1 | Viewed by 1957

Abstract

Rice husk is a waste byproduct of rice production. This material has a moderate cost and is readily available, representing 20–22% of the biomass produced by rice cultivation. This study focused on the properties of rice husk in the remediation of soils contaminated [...] Read more.

Rice husk is a waste byproduct of rice production. This material has a moderate cost and is readily available, representing 20–22% of the biomass produced by rice cultivation. This study focused on the properties of rice husk in the remediation of soils contaminated by heavy metals. The effect of particle size, pH, and the presence of organic ligands on sorption efficiency was evaluated for Cd, Cu, and Mn. The continuous flow method was used to select suitable operative conditions and maximize the retention of heavy metals. Subsequently, pot experiments were carried out by growing two broadleaf plants, Lactuca sativa and Spinacia oleracea, in aliquots of soil collected in a Piedmont (Northwest Italy) site heavily contaminated by Cu, Cr, and Ni. Rice husk was added to the contaminated soil to evaluate its effectiveness in immobilizing heavy metals. The availability of Cr, Mn, Ni, Cu, Zn, Cd, and Pb in soil was studied using Tessier’s sequential extraction protocol. The content of the elements was also analyzed in plants and the uptake of heavy metals was evaluated in relation to the addition of rice husk. The growth of both plants was more efficient in the presence of rice husk due to its ability to reduce the mobility of heavy metals in the soil. The simplicity, cost-effectiveness, and scalability of its employment make the use of rice husk suitable for practical applications in soil remediation. Full article

(This article belongs to the Special Issue Safe Utilization and Ecological Restoration of Heavy Metal Polluted Farmland)

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17 pages, 3202 KiB

Open AccessArticle

Quantitative Soil Characterization for Biochar–Cd Adsorption: Machine Learning Prediction Models for Cd Transformation and Immobilization

by Muhammad Saqib Rashid, Yanhong Wang, Yilong Yin, Balal Yousaf, Shaojun Jiang, Adeel Feroz Mirza, Bing Chen, Xiang Li and Zhongzhen Liu

Toxics 2024, 12(8), 535; https://doi.org/10.3390/toxics12080535 - 24 Jul 2024

Viewed by 1637

Abstract

Soil pollution with cadmium (Cd) poses serious health and environmental consequences. The study investigated the incubation of several soil samples and conducted quantitative soil characterization to assess the influence of biochar (BC) on Cd adsorption. The aim was to develop predictive models for [...] Read more.

Soil pollution with cadmium (Cd) poses serious health and environmental consequences. The study investigated the incubation of several soil samples and conducted quantitative soil characterization to assess the influence of biochar (BC) on Cd adsorption. The aim was to develop predictive models for Cd concentrations using statistical and modeling approaches dependent on soil characteristics. The potential risk linked to the transformation and immobilization of Cd adsorption by BC in the soil could be conservatively assessed by pH, clay, cation exchange capacity, organic carbon, and electrical conductivity. In this study, Long Short-Term Memory (LSTM), Bidirectional Gated Recurrent Unit (BiGRU), and 5-layer CNN Convolutional Neural Networks (CNNs) were applied for risk assessments to establish a framework for evaluating Cd risk in BC amended soils to predict Cd transformation. In the case of control soils (CK), the BiGRU model showed commendable performance, with an

R^{2}

value of 0.85, indicating an approximate 85.37% variance in the actual Cd. The LSTM model, which incorporates sequence data, produced less accurate results (

R^{2} = 0.84)

, while the 5-layer CNN model had an R² value of 0.91, indicating that the CNN model could account for over 91% of the variation in actual Cd levels. In the case of BC-applied soils, the BiGRU model demonstrated a strong correlation between predicted and actual values with

R^{2}

(0.93), indicating that the model explained 93.21% of the variance in Cd concentrations. Similarly, the LSTM model showed a notable increase in performance with BC-treated soil data. The

R^{2}

value for this model stands at a robust

R^{2} (0.94)

, reflecting its enhanced ability to predict Cd levels with BC incorporation. Outperforming both recurrent models, the 5-layer CNN model attained the highest precision with an

R^{2}

value of 0.95, suggesting that 95.58% of the variance in the actual Cd data can be explained by the CNN model’s predictions in BC-amended soils. Consequently, this study suggests developing ecological soil remediation strategies that can effectively manage heavy metal pollution in soils for environmental sustainability. Full article

(This article belongs to the Special Issue Safe Utilization and Ecological Restoration of Heavy Metal Polluted Farmland)

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18 pages, 3413 KiB

Open AccessArticle

Evaluating the Response of the Soil Bacterial Community and Lettuce Growth in a Fluorine and Cadmium Co-Contaminated Yellow Soil

by Mei Wang, Xiangxiang Chen, Yasir Hamid and Xiaoe Yang

Toxics 2024, 12(7), 459; https://doi.org/10.3390/toxics12070459 - 25 Jun 2024

Cited by 2 | Viewed by 1308

Abstract

The impact of cadmium (Cd) and fluorine (F) on plant and human health has provoked significant public concern; however, their combined effects on plant and soil bacterial communities have yet to be determined. Here, a pot experiment was conducted to evaluate the effects [...] Read more.

The impact of cadmium (Cd) and fluorine (F) on plant and human health has provoked significant public concern; however, their combined effects on plant and soil bacterial communities have yet to be determined. Here, a pot experiment was conducted to evaluate the effects of exogenous F, Cd, and their combination (FCd) on lettuce growth and soil bacterial communities. The results revealed that F and Cd concentrations in lettuce ranged from 63.69 to 219.45 mg kg⁻¹ and 1.85 to 33.08 mg kg⁻¹, respectively, presenting lower values in shoots than in the roots. Moreover, low contamination levels had no discernable influence on lettuce growth, but showed a synergistic negative on plant biomass when exogenous F and Cd exceeds 300 and 1.0 mg kg⁻¹, respectively. The results of 16S rRNA gene sequencing indicated that the most abundant bacterial community at the phylum level was Proteobacteria, with the relative abundance ranging from 33.42% to 44.10% across all the treatments. The contaminants had little effect on bacterial richness but impacted the structure of bacterial communities. The PCoA showed that compartment and contaminants were the primary contributors to the largest source of community variation, while the VPA indicated that F and Cd synergistically affected the bacterial communities. In turn, lettuce plants could enhance the resistance to the combined stress by increasing the relative abundance of Oxyphotobacteria, Subgroup 6, Thermoleophilia, and TK10 classes in the rhizosphere. Full article

(This article belongs to the Special Issue Safe Utilization and Ecological Restoration of Heavy Metal Polluted Farmland)

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12 pages, 2398 KiB

Open AccessArticle

Temporal and Spatial Variation of Toxic Metal Concentrations in Cultivated Soil in Jiaxing, Zhejiang Province, China: Characteristics and Mechanisms

by Mengzhuo Cao, Yanbo Jia, Xin Lu, Jinfa Huang, Yanlai Yao, Leidong Hong, Weijing Zhu, Weiping Wang, Fengxiang Zhu and Chunlai Hong

Toxics 2024, 12(6), 390; https://doi.org/10.3390/toxics12060390 - 26 May 2024

Cited by 1 | Viewed by 1067

Abstract

The toxic metal (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) pollution in 250 agricultural soil samples representing the urban area of Jiaxing was studied to investigate the temporal and spatial variations. Compared to the early 1990s, the pollution level has increased. [...] Read more.

The toxic metal (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) pollution in 250 agricultural soil samples representing the urban area of Jiaxing was studied to investigate the temporal and spatial variations. Compared to the early 1990s, the pollution level has increased. Industry and urbanization were the main factors causing toxic metal pollution on temporal variation, especially the use of feed containing toxic metals. The soil types and crop cultivation methods are the main factors causing toxic metal pollution on spatial variation. Although the single-factor pollution indices of all the toxic metals were within the safe limits, as per the National Soil Environmental Quality Standard (risk screening value), if the background values of soil elements in Jiaxing City are used as the standard, the pollution index of all the elements surveyed exceeds 1.0, reaching a level of mild pollution. The soil samples investigated were heavily contaminated with toxic metal compounds, and their levels increased over time. This situation poses potential ecological and health risks. Full article

(This article belongs to the Special Issue Safe Utilization and Ecological Restoration of Heavy Metal Polluted Farmland)

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16 pages, 5830 KiB

Open AccessArticle

A Modified Model for Quantitative Heavy Metal Source Apportionment and Pollution Pathway Identification

by Maodi Wang, Pengyue Yu, Zhenglong Tong, Xingyuan Shao, Jianwei Peng, Yasir Hamid and Ying Huang

Toxics 2024, 12(6), 382; https://doi.org/10.3390/toxics12060382 - 23 May 2024

Cited by 2 | Viewed by 1754

Abstract

Current source apportionment models have successfully identified emission sources and quantified their contributions. However, when being utilized for heavy metal source apportion in soil, their accuracy needs to be improved, regarding migration patterns. Therefore, this work intended to improve the pre-existing principal component [...] Read more.

Current source apportionment models have successfully identified emission sources and quantified their contributions. However, when being utilized for heavy metal source apportion in soil, their accuracy needs to be improved, regarding migration patterns. Therefore, this work intended to improve the pre-existing principal component analysis and multiple linear regression with distance (PCA-MLRD) model to effectively locate pollution pathways (traffic emissions, irrigation water, atmospheric depositions, etc.) and achieve a more precise quantification. The dataset of soil heavy metals was collected from a typical area in the Chang-Zhu-Tan region, Hunan, China in 2021. The identification of the contribution of soil parent material was accomplished through enrichment factors and crustal reference elements. Meanwhile, the anthropogenic emission was identified with principal component analysis and GeoDetector. GeoDetector was used to accurately point to the pollution source from a spatial differentiation perspective. Subsequently, the pollution pathways linked to the identified sources were determined. Non-metal manufacturing factories were found to be significant anthropogenic sources of local soil contamination, mainly through rivers and atmospheric deposition. Furthermore, the influence of irrigation water on heavy metals showed a more pronounced effect within a distance of 1000 m, became weaker after that, and then gradually disappeared. This model may offer improved technical guidance for practical production and the management of soil heavy metal contamination. Full article

(This article belongs to the Special Issue Safe Utilization and Ecological Restoration of Heavy Metal Polluted Farmland)

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