作者机构：
[Haodong Zhang; Ning Su; Zhi Peng; Xizhe Luo; Sihai Qin; Mengjiao Huang; Jun Xie] College of Resources, Hunan Agricultural University, Changsha 410128, China;Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Changsha 410128, China;National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, Changsha 410128, China;[Gongwen Luo; Chang Tian; Xiangmin Rong; Guixian Xie] College of Resources, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Changsha 410128, China<&wdkj&>National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, Changsha 410128, China
通讯机构：
[Guixian Xie] C;College of Resources, Hunan Agricultural University, Changsha 410128, China<&wdkj&>Hunan Provincial Key Laboratory of Farmland Pollution Control and Agricultural Resources Use, Changsha 410128, China<&wdkj&>National Engineering Laboratory for Efficient Utilization of Soil and Fertilizer Resources, Changsha 410128, China
关键词：
N and P fertilizer;Rice-oilseed rape rotation;Soil properties;Runoff loss;Grain yield
摘要：
To address environmental pollution from agricultural non-point sources, it is feasible to reduce nitrogen (N) or phosphorus (P) inputs in farmland ecosystems. However, the combined effects of simultaneously reducing both N and P fertilizers remain unclear. Hence, we carried out a two-year field experiment (2020–2022) in the Dongting Lake region, China, to examine the impact of decreasing N and P fertilizer inputs on the soil properties, N and P runoff losses, and grain yields under rice-oilseed rape rotation in southern China. Compared to traditional management (rice, 210 kg N ha −1 and 105 kg P 2 O 5 ha −1 ; oilseed rape, 180 kg N ha −1 and 90 kg P 2 O 5 ha −1 ), the 10–30 % reduction in N and P inputs decreased total N runoff losses by 19.2–48.7 % (rice seasons; 3.12–7.92 kg ha −1 ) and 26.1–58.1 % (oilseed rape seasons; 1.17–2.61 kg ha −1 ), and total P losses by 35.5–59.7 % (rice seasons; 0.95–1.59 kg ha −1 ) and 30.3–58.5 % (oilseed rape seasons; 0.20–0.38 kg ha −1 ). Moreover, grain yields were maintained despite nutrient input reductions. The partial least square structural equation model showed that the soil total N, soil available N, and soil available P positively affected the grain yields, while the N and P runoff losses had a significant negative effect on the grain yields. In conclusion, the reduction of N and P fertilizer by 30 % achieved optimal outcomes, effectively reducing environmental risks while maintaining agricultural productivity.
To address environmental pollution from agricultural non-point sources, it is feasible to reduce nitrogen (N) or phosphorus (P) inputs in farmland ecosystems. However, the combined effects of simultaneously reducing both N and P fertilizers remain unclear. Hence, we carried out a two-year field experiment (2020–2022) in the Dongting Lake region, China, to examine the impact of decreasing N and P fertilizer inputs on the soil properties, N and P runoff losses, and grain yields under rice-oilseed rape rotation in southern China. Compared to traditional management (rice, 210 kg N ha −1 and 105 kg P 2 O 5 ha −1 ; oilseed rape, 180 kg N ha −1 and 90 kg P 2 O 5 ha −1 ), the 10–30 % reduction in N and P inputs decreased total N runoff losses by 19.2–48.7 % (rice seasons; 3.12–7.92 kg ha −1 ) and 26.1–58.1 % (oilseed rape seasons; 1.17–2.61 kg ha −1 ), and total P losses by 35.5–59.7 % (rice seasons; 0.95–1.59 kg ha −1 ) and 30.3–58.5 % (oilseed rape seasons; 0.20–0.38 kg ha −1 ). Moreover, grain yields were maintained despite nutrient input reductions. The partial least square structural equation model showed that the soil total N, soil available N, and soil available P positively affected the grain yields, while the N and P runoff losses had a significant negative effect on the grain yields. In conclusion, the reduction of N and P fertilizer by 30 % achieved optimal outcomes, effectively reducing environmental risks while maintaining agricultural productivity.
摘要：
Submerged macrophytes play a crucial role in lake ecosystems, and their survival is dependent upon their ability to cope with variable environmental stress. Therefore, studying the plastic response of submerged macrophytes' resource allocation and functional traits to the environment may provide insights helpful for ecological restoration practices. In September 2021, a field survey was conducted in the Erhai Lake, where samples of Ottelia acuminata, and functional traits and biomass allocation in relation to water depth were measured. The study found that O. acuminata exhibited large intraspecific variations to adapt to environmental stress, and the average intraspecific variation was 55.86%. In the current environment, this study suggested that the optimal growth depth for O. acuminata is moderate water depth (1-2m). The results of allometric growth analysis showed that the resource allocation of O. acuminata responded to the water depth with the synergistic effect of leaf area and shoot height. In shallow water, the resource allocation of O. acuminata was mainly used for leaf area growth, while in deep water, the increase of shoot height was mainly used to cope with stress. This research will provide us useful information for the ecological restoration and protection of this endemic and endangered submerged macrophyte.
摘要：
Plant growth regulators such as paclobutrazol are widely used in agriculture, but repeated applications can accumulate in soil and crops, negatively impacting the environment and microbial communities. This study conducted incubation and plant-growth experiments to evaluate the combined effects of nano zerovalent iron (nZVI) and urease inhibitor (NBPT) on paclobutrazol degradation, crop yields, and microbial communities. Sole nZVI reduced paclobutrazol residues and increased endophytic microbial diversity and functionality but destabilized soil microbial communities. The combination of nZVI and NBPT significantly reduced paclobutrazol residues in lettuce by 34.4% and in soil by 15.4% while improving the crop yield. NBPT mitigated the negative impact of nZVI on soil microbial stability and enhanced its effects on paclobutrazol degradation and yield stimulation. The combined treatment also improved the ecological functions of endophytic microbes and maintained the stable functional potentials of soil microbial communities, providing a basis for managing paclobutrazol residue risks and enhancing crop safety.
摘要：
As a dominant wetland species in Dongting Lake, Phragmites australis fueled China's papermaking industry for six decades (1960s-2018), driving regional growth but causing ecological harm through small mills' unregulated wastewater discharge. Policy shifts from 2007 restructuring to the 2018 pulping ban improved environmental conditions yet triggered socioeconomic challenges, notable post-ban reed disposal crises. This study employs a multidisciplinary framework to systematically examine Phragmites australis resource utilization patterns, environmental-economic trade-offs, and policy implementation impacts in Dongting Lake. Specifically, it conducts comprehensive analysis of the ecological value and multifunctional utilization pathways of Phragmites australis in the lake ecosystem, clarifies the rationale behind both “reapers” and “conservatives” stances, and proposes adaptive strategies via a zoning-based framework. By integrating ecological stewardship, value-chain optimization, and circular economy principles, the research advances solutions to balance sustainable wetland conservation with resource utilization.
As a dominant wetland species in Dongting Lake, Phragmites australis fueled China's papermaking industry for six decades (1960s-2018), driving regional growth but causing ecological harm through small mills' unregulated wastewater discharge. Policy shifts from 2007 restructuring to the 2018 pulping ban improved environmental conditions yet triggered socioeconomic challenges, notable post-ban reed disposal crises. This study employs a multidisciplinary framework to systematically examine Phragmites australis resource utilization patterns, environmental-economic trade-offs, and policy implementation impacts in Dongting Lake. Specifically, it conducts comprehensive analysis of the ecological value and multifunctional utilization pathways of Phragmites australis in the lake ecosystem, clarifies the rationale behind both “reapers” and “conservatives” stances, and proposes adaptive strategies via a zoning-based framework. By integrating ecological stewardship, value-chain optimization, and circular economy principles, the research advances solutions to balance sustainable wetland conservation with resource utilization.
期刊：
Chemical Engineering Journal,2025年:167445 ISSN：1385-8947
通讯作者：
Shengguo Xue
作者机构：
[Xue Li; Feng Zhu; Yayuan Huang; Chuan Wu] School of Metallurgy and Environment, Central South University, Changsha 410083, PR China;[Jingpei Feng] Jiangxi Copper Corporation limited, Guixi 335400, PR China;[Wenshun Ke] College of Resources and Environment, Hunan Agricultural University, Changsha 410127, PR China;[Haixia Liang] College of Environmental and Ecology, Taiyuan University of Technology, Jinzhong 030600, PR China;Research Center for Ecological Remediation of Mining & Metallurgical Sites, Central South University, Changsha 410083, PR China
通讯机构：
[Shengguo Xue] S;School of Metallurgy and Environment, Central South University, Changsha 410083, PR China<&wdkj&>College of Environmental and Ecology, Taiyuan University of Technology, Jinzhong 030600, PR China<&wdkj&>Research Center for Ecological Remediation of Mining & Metallurgical Sites, Central South University, Changsha 410083, PR China
摘要：
Microbial-assisted functional materials are emerging for addressing heavy metal pollution in soils. However, the mechanisms underlying their enhanced performance remain insufficiently understood. Here, we elucidated the synergistic mechanisms by which a phosphate-solubilizing bacterium ( Ochrobactrum anthropi , 2 % v / w ) and iron-doped hydroxyapatite (Fe-HAP, 3 % w /w) enhance the immobilization of lead (Pb), cadmium (Cd), and arsenic (As) through experimental evaluation and theoretical modeling. This strategy achieved immobilization efficiencies of up to 90.00 % (Pb), 75.11 % (Cd), and 79.85 % (As). O. anthropi enhanced phosphorus availability (10.82 mg/kg) and facilitated the transformation of amorphous to crystalline Fe oxides (from 22.64 % to 18.67 %), thereby promoting heavy metals immobilization via pre-activation, re-precipitation, and mineral phase reconstruction. Kinetic modeling identified chemisorption as the dominant removal mechanism, with the Langmuir model best describing AsO 4 3− adsorption through ligand exchange and inner-sphere complexation on Fe-based materials. Pb 2+ and Cd 2+ immobilization involved both monolayer and multilayer adsorption. Competitive ternary-adsorption experiments revealed strong Pb 2+ /Cd 2+ competition and cooperative Pb 2+ /AsO 4 3− and AsO 4 3− /Cd 2+ removal driven by co-precipitation. Peak deconvolution of high-resolution XPS spectra revealed Pb(NO 3 ) 2 /PbCO 3 and Pb O complexes, Cd(OH) 2 and Cd-Fe-OH species, and AsO 4 3− /HAsO 4 2− coordinated to surface oxygen groups. SEM-EDS, XRD and FT-IR confirmed the formation of stable minerals such as Pb 5 (PO 4 ) 3 OH/Cl, Cd(PO 4 ) 2 , Ca 5-x Cd x (PO 4 ) 3 (OH), FeAs 3 O 9 ·4H 2 O and Fe 3 AsO 7 . Partial least squares path modeling (PLS-PM) further revealed that Fe-HAP, O. anthropi , and induced soil geochemical changes synergistically enhanced metal stabilization. This study advances the mechanistic understanding of microbial-assisted material remediation for field-scale applications.
Microbial-assisted functional materials are emerging for addressing heavy metal pollution in soils. However, the mechanisms underlying their enhanced performance remain insufficiently understood. Here, we elucidated the synergistic mechanisms by which a phosphate-solubilizing bacterium ( Ochrobactrum anthropi , 2 % v / w ) and iron-doped hydroxyapatite (Fe-HAP, 3 % w /w) enhance the immobilization of lead (Pb), cadmium (Cd), and arsenic (As) through experimental evaluation and theoretical modeling. This strategy achieved immobilization efficiencies of up to 90.00 % (Pb), 75.11 % (Cd), and 79.85 % (As). O. anthropi enhanced phosphorus availability (10.82 mg/kg) and facilitated the transformation of amorphous to crystalline Fe oxides (from 22.64 % to 18.67 %), thereby promoting heavy metals immobilization via pre-activation, re-precipitation, and mineral phase reconstruction. Kinetic modeling identified chemisorption as the dominant removal mechanism, with the Langmuir model best describing AsO 4 3− adsorption through ligand exchange and inner-sphere complexation on Fe-based materials. Pb 2+ and Cd 2+ immobilization involved both monolayer and multilayer adsorption. Competitive ternary-adsorption experiments revealed strong Pb 2+ /Cd 2+ competition and cooperative Pb 2+ /AsO 4 3− and AsO 4 3− /Cd 2+ removal driven by co-precipitation. Peak deconvolution of high-resolution XPS spectra revealed Pb(NO 3 ) 2 /PbCO 3 and Pb O complexes, Cd(OH) 2 and Cd-Fe-OH species, and AsO 4 3− /HAsO 4 2− coordinated to surface oxygen groups. SEM-EDS, XRD and FT-IR confirmed the formation of stable minerals such as Pb 5 (PO 4 ) 3 OH/Cl, Cd(PO 4 ) 2 , Ca 5-x Cd x (PO 4 ) 3 (OH), FeAs 3 O 9 ·4H 2 O and Fe 3 AsO 7 . Partial least squares path modeling (PLS-PM) further revealed that Fe-HAP, O. anthropi , and induced soil geochemical changes synergistically enhanced metal stabilization. This study advances the mechanistic understanding of microbial-assisted material remediation for field-scale applications.
关键词：
Dendrocalamus brandisii;microbial communities;nutritional quality of bamboo shoots;soil microorganisms;soil nutrients
摘要：
OBJECTIVE: To explore the effects of soil nutrients and microbial communities on the quality of Dendrocalamus brandisii shoots in different regions, providing a scientific basis for their development and utilization. METHODS: Using seven different geographic sources of D. brandisii from Yunnan Province as research subjects, this study employs chemical analysis and high-throughput sequencing to reveal the relationship between soil nutrients, microbial functional groups, and the nutritional quality of bamboo shoots. RESULTS: The results indicate that there are significant differences in soil nutrient content among the regions (p < 0.05), with bamboo shoots from Baoshan Changning (CN) exhibiting the best overall nutritional quality. The key factors influencing bacterial community changes include pH, available phosphorus (AP), and available potassium (AK). In contrast, the main factors affecting fungal community changes are pH, soil organic matter (SOM), available potassium (AK), and total nitrogen (TN). This version maintains clarity and logical flow, making it easier for readers to understand the different factors influencing bacterial and fungal community changes. The diversity indices of soil microbial communities among different sources of Dendrocalamus brandisii show significant differences (p < 0.05). The dominant groups in the seven regions include Proteobacteria, Acidobacteriota, Actinobacteriota, Chloroflexi, Ascomycota, and Basidiomycota. The soil microbial community in Baoshan Changning (CN) shows significant structural differences compared to the other six regions, with the highest relative abundances of Chloroflexi and Acidobacteriota. In contrast, the highest relative abundance of Proteobacteria is found in Honghe Shiping (SP), while Actinobacteriota has the highest relative abundance in Yuxi Xinping (XP). RDA analysis indicates that soil nutrients (SOM, pH, AP, TN) affect the water content, soluble sugar, and crude fat of bamboo shoots. Additionally, the bacterial communities including Actinobacteriota, Chloroflexi, Patescibacteria, GAL15, and Cyanobacteria influence the water content, soluble sugar, ash content, protein, and lignin of bamboo shoots. DISCUSSION: In the fungal community, Basidiomycota, Kickxellomycota, Mucoromycota, unclassified-k-Fungi, and Glomeromycota affect the water content and tannin levels in bamboo shoots. In summary, soil nutrients and soil microorganisms are interconnected and work together to influence the quality of bamboo shoots.
关键词：
Bamboo-derived biochar;Dicyandiamide;Urease kinetics;Mineral nitrogen;Microbial community diversity
摘要：
Soil urease kinetics reflects the affinity and catalytic reaction rate of urease. However, an incomplete understanding on soil urease kinetic hampered the optimisation of soil N management practices for agricultural and forestry ecosystems. In the present study, different soils from farmland and forest land were subjected to the following four treatments: (1) blank control (CK), (2) bamboo-derived biochar application (BC), (3) DCD application (DC), and (4) combined application of bamboo-derived biochar and DCD (CBAD). In the forest soil, the urease kinetic half-saturation constant ( K m ) values decreased significantly by 28 %, 73 % and 45 % in the BC, DC and CBAD treatments, respectively. Similarly, in the agricultural soil, these values decreased by 46 %, 29 %, and 46 %, respectively. However, no significant difference in urease decomposition rates at saturated substrate concentrations ( V max ) was observed among the four treatments. The contribution percentages of soil abiotic and biotic (the composition of bacterial and fungal community) properties to the variability in K m were 58.6 % and 41.4 %, respectively. Biochar and DCD application improved the catalytic potential of urease in the agricultural and forest soils, which would not be conducive to the retention of nitrogen in soils. The increases in the catalytic potential of urease were associated with the increased content of mineral N and fungal community diversity under the application of biochar or DCD. Abiotic factors outweighed the microbial community composition in altering urease kinetics in various soils. These findings highlighted the necessity of nitrogen-fixing measures in soils amended with biochar or DCD and advanced our comprehension of how abiotic and biotic factors influence the urease kinetics in agricultural and forest soils.
Soil urease kinetics reflects the affinity and catalytic reaction rate of urease. However, an incomplete understanding on soil urease kinetic hampered the optimisation of soil N management practices for agricultural and forestry ecosystems. In the present study, different soils from farmland and forest land were subjected to the following four treatments: (1) blank control (CK), (2) bamboo-derived biochar application (BC), (3) DCD application (DC), and (4) combined application of bamboo-derived biochar and DCD (CBAD). In the forest soil, the urease kinetic half-saturation constant ( K m ) values decreased significantly by 28 %, 73 % and 45 % in the BC, DC and CBAD treatments, respectively. Similarly, in the agricultural soil, these values decreased by 46 %, 29 %, and 46 %, respectively. However, no significant difference in urease decomposition rates at saturated substrate concentrations ( V max ) was observed among the four treatments. The contribution percentages of soil abiotic and biotic (the composition of bacterial and fungal community) properties to the variability in K m were 58.6 % and 41.4 %, respectively. Biochar and DCD application improved the catalytic potential of urease in the agricultural and forest soils, which would not be conducive to the retention of nitrogen in soils. The increases in the catalytic potential of urease were associated with the increased content of mineral N and fungal community diversity under the application of biochar or DCD. Abiotic factors outweighed the microbial community composition in altering urease kinetics in various soils. These findings highlighted the necessity of nitrogen-fixing measures in soils amended with biochar or DCD and advanced our comprehension of how abiotic and biotic factors influence the urease kinetics in agricultural and forest soils.
通讯机构：
[Liu, S ; Peng, XH ] C;Chinese Acad Sci, Inst Soil Sci, State Key Lab Soil & Sustainable Agr, Nanjing 211135, Peoples R China.;Chinese Acad Agr Sci, Inst Agr Resources & Reg Planning, State Key Lab Efficient Utilizat Arid & Semiarid A, Beijing 100081, Peoples R China.
关键词：
SOC fractions;Straw return;Underground water table;C-13 NMR
摘要：
Various groundwater table levels in paddy soil aggravate the complexity of soil organic carbon (SOC) sequestration under redox conditions. We investigated a long-term experimental field consisting of two groundwater tables (SWT, shallow groundwater table; DWT, deep groundwater table) and three straw application rates (NPK, without straw return; LOM, low rate of straw return; HOM, high rate of straw return). Soil samples from 0–10, 10–20 and 20–40 cm soil layers were collected and analyzed. Results revealed that SOC fraction contents significantly decreased with increasing soil depth, while SOC stability showed an opposite trend ( P < 0.05). In the 0–20 cm soil layer, straw return increased SOC fraction concentrations, resulting in higher C stocks. In the 20–40 cm soil layer, a significant decrease in SOC was explained by remarkable MOC reduction with straw addition under SWT ( P < 0.05), whereas no significant changes were observed under DWT. Relative to NPK, straw application notably increased the proportions of O-alkyl C and Carbonyl C under SWT and DWT in topsoil layer, respectively ( P < 0.05). In the deep soil layer, straw addition increased Aromatic C but decreased O-alkyl C proportions under SWT, resulting in higher aromaticity and hydrophobicity ( P < 0.05), while contrasting changing patterns were observed under DWT when compared to NPK. Hierarchical clustering analysis indicated that soil properties and SOC dynamics were primarily determined by straw return under SWT, while mainly driven by soil depth under DWT. This study highlights the importance of understanding the dynamics of SOC throughout the whole profile to groundwater table management. A preferable straw return strategy is proposed for different groundwater management based on the trade-off between economic and environmental benefits. A lower straw return amount was suggested under SWT from an economic perspective, whereas a higher straw return amount was recommended under DWT treatment for the higher increase of SOC.
Various groundwater table levels in paddy soil aggravate the complexity of soil organic carbon (SOC) sequestration under redox conditions. We investigated a long-term experimental field consisting of two groundwater tables (SWT, shallow groundwater table; DWT, deep groundwater table) and three straw application rates (NPK, without straw return; LOM, low rate of straw return; HOM, high rate of straw return). Soil samples from 0–10, 10–20 and 20–40 cm soil layers were collected and analyzed. Results revealed that SOC fraction contents significantly decreased with increasing soil depth, while SOC stability showed an opposite trend ( P < 0.05). In the 0–20 cm soil layer, straw return increased SOC fraction concentrations, resulting in higher C stocks. In the 20–40 cm soil layer, a significant decrease in SOC was explained by remarkable MOC reduction with straw addition under SWT ( P < 0.05), whereas no significant changes were observed under DWT. Relative to NPK, straw application notably increased the proportions of O-alkyl C and Carbonyl C under SWT and DWT in topsoil layer, respectively ( P < 0.05). In the deep soil layer, straw addition increased Aromatic C but decreased O-alkyl C proportions under SWT, resulting in higher aromaticity and hydrophobicity ( P < 0.05), while contrasting changing patterns were observed under DWT when compared to NPK. Hierarchical clustering analysis indicated that soil properties and SOC dynamics were primarily determined by straw return under SWT, while mainly driven by soil depth under DWT. This study highlights the importance of understanding the dynamics of SOC throughout the whole profile to groundwater table management. A preferable straw return strategy is proposed for different groundwater management based on the trade-off between economic and environmental benefits. A lower straw return amount was suggested under SWT from an economic perspective, whereas a higher straw return amount was recommended under DWT treatment for the higher increase of SOC.
摘要：
This study aimed to systematically investigate the effects of low-temperature pyrolysis on the physicochemical properties and their internal connection. This work evaluated the influences of low-temperature pyrolysis on proximate analysis, element composition, stability, and structural features of prepared straw biochar from two feedstocks pyrolyzed at 225 °C to 600 °C. The different indicators, including yield, pH, fixed carbon (FC), volatile matter (VM), ash, C, H, O, N, P, K, Mg, Zn, and stability indexes, all followed exponential function with temperature ( R 2 > 0.82). As the pyrolysis temperature increased from 225 °C to 400 °C, most physicochemical properties of straw biochar demonstrated a rapid change. Additionally, 400°C was a crucial turning point, all biochar physicochemical indicators showed a slowly changing trend at temperatures above 400 °C. Factor and hierarchical clustering analyses yielded identical results. The physicochemical properties can be classified into two groups of intrinsically connected properties: (1) yield, O, H, VM, VM/FC, H/C, and O/C, and (2) N, Zn, Mg, P, K, FC, pH, ash, and C. The quantitative relationships between ash and other properties of the tobacco and rice straw biochar revealed that ash was positively and exponentially associated with pH, FC, C, P, K, Mg, and Zn ( R 2 = 0.73–0.96). Conversely, negative exponential relationships were found with yield, VM, H, O, VM/FC, H/C, and O/C ( R 2 = 0.83–0.96). This work supplies data support for a better understanding of the intrinsic characteristics of straw biochar, especially in scientific preparation and utilization.
This study aimed to systematically investigate the effects of low-temperature pyrolysis on the physicochemical properties and their internal connection. This work evaluated the influences of low-temperature pyrolysis on proximate analysis, element composition, stability, and structural features of prepared straw biochar from two feedstocks pyrolyzed at 225 °C to 600 °C. The different indicators, including yield, pH, fixed carbon (FC), volatile matter (VM), ash, C, H, O, N, P, K, Mg, Zn, and stability indexes, all followed exponential function with temperature ( R 2 > 0.82). As the pyrolysis temperature increased from 225 °C to 400 °C, most physicochemical properties of straw biochar demonstrated a rapid change. Additionally, 400°C was a crucial turning point, all biochar physicochemical indicators showed a slowly changing trend at temperatures above 400 °C. Factor and hierarchical clustering analyses yielded identical results. The physicochemical properties can be classified into two groups of intrinsically connected properties: (1) yield, O, H, VM, VM/FC, H/C, and O/C, and (2) N, Zn, Mg, P, K, FC, pH, ash, and C. The quantitative relationships between ash and other properties of the tobacco and rice straw biochar revealed that ash was positively and exponentially associated with pH, FC, C, P, K, Mg, and Zn ( R 2 = 0.73–0.96). Conversely, negative exponential relationships were found with yield, VM, H, O, VM/FC, H/C, and O/C ( R 2 = 0.83–0.96). This work supplies data support for a better understanding of the intrinsic characteristics of straw biochar, especially in scientific preparation and utilization.
摘要：
Cadmium (Cd) contamination is a major concern due to its toxicity and bioaccumulation in crops. The study researched the impact of rape (Brassica campestris) cultivation and influence of straw management on Cd accumulation in rice (Oryza sativa L.) under rape-rice rotation system. Field experiments were set in moderately Cd-contaminated farmlands, with treatments including rape-rice rotation with straw removal (NR), rape-rice rotation with straw return (RR), and single cropping rice (SR). In contrast with SR, the NR effectively reduced 6.67-19.59% soil available Cd and the 37.18-39.10% rice grains Cd accumulation during 3 years. Compared with the RR, SR significantly decreased 17.17-27.78% soil available Cd concentrations and 33.30-53.84% rice grain Cd accumulation. Soil physical and chemical properties were influenced by rape cultivation and straw return, further affecting Cd mobility. This study underscores that rape-rice rotation with straw removal can be an effective tactic for reducing the Cd contamination in rice grains and improve soil environment. This research provides critical insights into sustainable agricultural practices for Cd-contaminated soils, offering practical solutions for mitigating Cd risk in rice, while highlighting the importance of straw management in crop rotations.
期刊：
Separation and Purification Technology,2025年361:131592 ISSN：1383-5866
通讯作者：
Leng, Lijian;Zhan, Hao;Li, HL
作者机构：
[Zheng, Huihui; Peng, Haoyi; Leng, Lijian; Li, HL; Zhan, Hao; Li, Hailong] Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Peoples R China.;[Xiong, Ting; Leng, Lijian] Xiangjiang Lab, Changsha 410205, Peoples R China.;[Wu, Zhibin; Shen, Tian] Hunan Agr Univ, Coll Resources & Environm, Changsha 410128, Hunan, Peoples R China.;[Xiong, Ting] Hunan Univ Technol & Business, Sch Adv Interdisciplinary Studies, Changsha 410205, Peoples R China.;[Liu, Shengqiang] Aerosp Kaitian Environm Technol Co Ltd, Changsha 410100, Peoples R China.
通讯机构：
[Leng, LJ; Li, HL ; Zhan, H] C;Cent South Univ, Sch Energy Sci & Engn, Changsha 410083, Peoples R China.
关键词：
Cation exchange capacity;Heavy metal removal;Bio-char;Pyrogenic carbon material;Machine learning
摘要：
The application of biochar in heavy metal removal has attracted significant attention due to its characteristics. However, engineering biochar materials through trial-and-error methods is traditionally applied, but it is time-consuming and labor-intensive. Applying machine learning (ML) promises to substantially enhance the efficiency of engineering biochar with desired properties. Here, ML was employed for the first time to predict multiple properties of biochar that are critical to heavy metal adsorption, such as cation exchange capacity (CEC). Previous studies have focused on correlations between the CEC and application performance of biochar, but no study has reported the direct prediction of heavy metal adsorption capacity (qe) from biomass. Therefore, a biomass—production—application hybrid ML model (test R 2 0.996) was constructed by integrating the biomass—production—biochar-properties ML model (test R 2 0.941) and the biochar-properties—application (heavy metal adsorption) ML model (test R 2 0.960). This innovative hybrid model facilitated the screening of biomass feedstock and the optimization of pyrolysis conditions, using only elemental composition data of biomass. With nine biomass feedstocks in the lab, the hybrid ML model effectively provided the optimum solution for producing biochar with the highest q e (e.g., predicted q e of ∼0.60 mmol/g for Cd 2+ ). Finally, the experimental verification of the optimum solution showed that the adsorption capacities of the as-produced optimum biochar were comparable with the hybrid model-predicted ones (validation R 2 0.859), and the adsorption mechanism study echoed the dominant role of cation exchange, showing the great potential of such hybrid ML models to promote the production of designer biochar.
The application of biochar in heavy metal removal has attracted significant attention due to its characteristics. However, engineering biochar materials through trial-and-error methods is traditionally applied, but it is time-consuming and labor-intensive. Applying machine learning (ML) promises to substantially enhance the efficiency of engineering biochar with desired properties. Here, ML was employed for the first time to predict multiple properties of biochar that are critical to heavy metal adsorption, such as cation exchange capacity (CEC). Previous studies have focused on correlations between the CEC and application performance of biochar, but no study has reported the direct prediction of heavy metal adsorption capacity (qe) from biomass. Therefore, a biomass—production—application hybrid ML model (test R 2 0.996) was constructed by integrating the biomass—production—biochar-properties ML model (test R 2 0.941) and the biochar-properties—application (heavy metal adsorption) ML model (test R 2 0.960). This innovative hybrid model facilitated the screening of biomass feedstock and the optimization of pyrolysis conditions, using only elemental composition data of biomass. With nine biomass feedstocks in the lab, the hybrid ML model effectively provided the optimum solution for producing biochar with the highest q e (e.g., predicted q e of ∼0.60 mmol/g for Cd 2+ ). Finally, the experimental verification of the optimum solution showed that the adsorption capacities of the as-produced optimum biochar were comparable with the hybrid model-predicted ones (validation R 2 0.859), and the adsorption mechanism study echoed the dominant role of cation exchange, showing the great potential of such hybrid ML models to promote the production of designer biochar.
摘要：
Abundant evidences have demonstrated that below-ground feedback mediated by crop diversification is essential for enhancing crop productivity. However, there is a knowledge gap about the mechanism underlying intercropping-driven productivity gain from the perspective of interactive scenarios of root traits and arbuscular mycorrhizal fungi (AMF). Herein, a ten-year field experiment was employed to reveal the differences of rhizosphere AMF community and root functional traits between maize monocropping and intercropping systems (maize-peanut, maize-soybean, maize-gingelly, and maize-sweet potato), as well as their relationships with maize productivity. AMF community traits were identified by high-throughput sequencing combined with bioinformatics and ecological analysis. Plant biomass, carbon (C) and nutrient content and accumulation were considered as productivity indicators, and root activity and morphology were considered as root functional traits. Compared with monocropping system, intercropping systems showed higher maize biomass, C accumulation and nutrient uptake (P < 0.05), and the intercropping advantage varied at different growth stages. Monocropping and intercropping systems showed a significant difference in maize root activity and morphology. AMF colonization significantly increased in all systems as maize developed, with the maize-peanut and maize-soybean consistently keeping higher colonization than other systems. The AMF communities of all systems except maize-gingelly were with greater force governed by deterministic assembly processes (MST < 50 %), in which monocropping system presented the lowest stochasticity ratio. AMF community composition in maize-soybean system was most deterministically driven and most diffusion-limited in neutral model. Compared with monocropping system, AMF community network showed a higher robustness in intercropping systems. And the ASVs of AMF community enriched by intercropping systems mainly belonged to genus Paraglomus, Glomus, and Claroideoglomus. The colonization, Shannon index, community composition, and core taxa (Glomus) of rhizosphere AMF influenced plant biomass and C and nutrient accumulation directly or indirectly by regulating root activity and morphology. Root activity also affected these maize productivity indicators directly or indirectly by regulating AMF community composition and core taxa (Claroideoglomus and Paraglomus). This work highlights the benefits of rhizosphere AMF in productivity gain of intercropping systems, and meanwhile, underscores the importance of AMF and root interactions in crop production.
Abundant evidences have demonstrated that below-ground feedback mediated by crop diversification is essential for enhancing crop productivity. However, there is a knowledge gap about the mechanism underlying intercropping-driven productivity gain from the perspective of interactive scenarios of root traits and arbuscular mycorrhizal fungi (AMF). Herein, a ten-year field experiment was employed to reveal the differences of rhizosphere AMF community and root functional traits between maize monocropping and intercropping systems (maize-peanut, maize-soybean, maize-gingelly, and maize-sweet potato), as well as their relationships with maize productivity. AMF community traits were identified by high-throughput sequencing combined with bioinformatics and ecological analysis. Plant biomass, carbon (C) and nutrient content and accumulation were considered as productivity indicators, and root activity and morphology were considered as root functional traits. Compared with monocropping system, intercropping systems showed higher maize biomass, C accumulation and nutrient uptake (P < 0.05), and the intercropping advantage varied at different growth stages. Monocropping and intercropping systems showed a significant difference in maize root activity and morphology. AMF colonization significantly increased in all systems as maize developed, with the maize-peanut and maize-soybean consistently keeping higher colonization than other systems. The AMF communities of all systems except maize-gingelly were with greater force governed by deterministic assembly processes (MST < 50 %), in which monocropping system presented the lowest stochasticity ratio. AMF community composition in maize-soybean system was most deterministically driven and most diffusion-limited in neutral model. Compared with monocropping system, AMF community network showed a higher robustness in intercropping systems. And the ASVs of AMF community enriched by intercropping systems mainly belonged to genus Paraglomus, Glomus, and Claroideoglomus. The colonization, Shannon index, community composition, and core taxa (Glomus) of rhizosphere AMF influenced plant biomass and C and nutrient accumulation directly or indirectly by regulating root activity and morphology. Root activity also affected these maize productivity indicators directly or indirectly by regulating AMF community composition and core taxa (Claroideoglomus and Paraglomus). This work highlights the benefits of rhizosphere AMF in productivity gain of intercropping systems, and meanwhile, underscores the importance of AMF and root interactions in crop production.
作者机构：
[Quan Zhang; Bo Li; Qihong Zhu; Daoyou Huang; Chao Xu; Hanhua Zhu] Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China;University of Chinese Academy of Sciences, Beijing 100049, China;[Haifei Chen; Qiren Wen] School of Resources and Environment, Hunan Agricultural University, Changsha 410125, China;[Tianyi Yan; Jingheng Zhou] Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China<&wdkj&>University of Chinese Academy of Sciences, Beijing 100049, China
通讯机构：
[Quan Zhang; Hanhua Zhu] K;Key Laboratory of Agro-Ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha 410125, China
摘要：
Manganese (Mn) is widely used to control cadmium (Cd) and arsenic (As) uptake by rice, but the effects of different Mn forms and concentrations on Cd/As movement in the soil-rice system are unclear. The study investigated the mechanisms by which three Mn compounds affected the accumulation of Cd/As in rice under different application rates. MnO 2 , MnSO 4 , and MnCO 3 treatments significantly reduced grains Cd levels by 27.6 %, 30.2 %, and 28.1 %, respectively, while As levels were less consistently affected. Three forms of Mn fertilizers enhanced the conversion of exchangeable to carbonate bound-Cd, which closely related to the increase of soil pH. MnO 2 and MnCO 3 reduced Cd translocation by increasing Cd/As adsorption on iron plaques, and MnSO 4 and MnCO 3 decreased Cd translocation by boosting root SOD and Cys levels. Transcriptome analysis revealed that Mn 2+ upregulated genes involved in the antioxidant defense system, limited Cd transport by enhancing OsABCC1 and OsHMA3 expression, and promoted As translocation by increasing OsLsi2 expression. Overall, different forms of Mn fertilizers effectively reduced Cd toxicity by fixing Cd in soil carbonate and iron plaques, and restricting Cd transport. Although Mn fertilizers reduced As availability in soil and affected As absorption in rice, they have certain limitations and need to be further explored. These findings reveal the mechanism by which different forms of Mn regulate the fixation and migration behavior of Cd and As, providing new ideas and theoretical basis for reducing the environmental risk of Cd and As.
Manganese (Mn) is widely used to control cadmium (Cd) and arsenic (As) uptake by rice, but the effects of different Mn forms and concentrations on Cd/As movement in the soil-rice system are unclear. The study investigated the mechanisms by which three Mn compounds affected the accumulation of Cd/As in rice under different application rates. MnO 2 , MnSO 4 , and MnCO 3 treatments significantly reduced grains Cd levels by 27.6 %, 30.2 %, and 28.1 %, respectively, while As levels were less consistently affected. Three forms of Mn fertilizers enhanced the conversion of exchangeable to carbonate bound-Cd, which closely related to the increase of soil pH. MnO 2 and MnCO 3 reduced Cd translocation by increasing Cd/As adsorption on iron plaques, and MnSO 4 and MnCO 3 decreased Cd translocation by boosting root SOD and Cys levels. Transcriptome analysis revealed that Mn 2+ upregulated genes involved in the antioxidant defense system, limited Cd transport by enhancing OsABCC1 and OsHMA3 expression, and promoted As translocation by increasing OsLsi2 expression. Overall, different forms of Mn fertilizers effectively reduced Cd toxicity by fixing Cd in soil carbonate and iron plaques, and restricting Cd transport. Although Mn fertilizers reduced As availability in soil and affected As absorption in rice, they have certain limitations and need to be further explored. These findings reveal the mechanism by which different forms of Mn regulate the fixation and migration behavior of Cd and As, providing new ideas and theoretical basis for reducing the environmental risk of Cd and As.
关键词：
economic benefits;growth;nutrient use efficiency;silicon;tobacco
摘要：
Silicon (Si) is widely used in agricultural crop practices. However, the effects of varying Si application rates on tobacco growth and quality remain unclear. Therefore, this study applied four different Si concentrations, i.e., 0, 750, 1500 and 3000 kg/ha of Si (S0, S50, S100 and S200), examined the impact of different Si concentrations on tobacco (Nicotiana tabacum L. 'Yunyan 87') growth, nutrient utilization, and economic quality under field conditions. The results demonstrated that Si application significantly improved tobacco growth, the biomass significantly increased by 19.5%-26.53%; during button stage, the plant height significantly increased by 15.38%-19%. Si also enhanced nutrient use efficiency, particularly for nitrogen and potassium. The utilization efficiency of N and K fertilizer were significantly increased by 27.42%-43.71% and 40.25% - 44.63%, respectively. Furthermore, Si improved leaf physical properties, enhancing single-leaf weight and leaf area, while reducing leaf density and midrib ratio, optimizing leaf quality by improving the sugar-alkali ratio and potassium-chloride balance. Notably, the reducing sugar content in upper leaves increased by 15.21% with S50 treatment, while the chlorine content in middle leaves was decreased by 11.11% with S100. Additionally, among all treatments, S50 achieved the highest proportion (94.75%) of medium and high-quality tobacco leaves, along with a 15.70% increase in yield and a 30.76%boost in output value compared to S0. However, excessive Siapplication (3000 kg/ha) negatively affected quality, increasing nicotine levels and disrupting the sugar-alkali ratio, which elevate leaf irritancy. In conclusion, moderate Si application (750-1500 kg/ha) is an effective strategy for enhancing tobacco yield and quality, offering a sustainable approach to optimize cultivation practices.
摘要：
Nonmetallic doped biochar showed great potential for activating persulfates, gaining considerable attention in environmental remediation. However, its activating mechanism and phytotoxicity remain unclear. Herein, a novel B-doped biochar (BBC) was synthesized using waste tea residue and boric acid to activate ammonium persulfate (APS) for efficient degrade quinclorac (QC) in irrigation water. BBC exhibited remarkable catalytic performance for APS, achieving a QC removal efficiency of 91% within 30 min under optimal conditions (0.5 g·L -1 BBC and 0.5 mM APS). The QC degradation efficiency was closely correlated with the BC 2 O groups on BBC, which could enhance electron-transfer between BBC and APS. Quenching experiments and characterization tests confirmed that the electron transfer and 1 O 2 were the main approaches to degrade QC. Seven intermediates of the process of QC degradation were identified, generated mainly by the non-radical ways, and their toxicity was much lower than QC. Pot experiments confirmed that the BBC/APS system can not only alleviate the phytotoxicity of QC but also promote the growth of tobacco. This work provides a new idea and theoretical basis for the removal of herbicide residues using non-metallic biochar for APS activation in the agricultural environments.
Nonmetallic doped biochar showed great potential for activating persulfates, gaining considerable attention in environmental remediation. However, its activating mechanism and phytotoxicity remain unclear. Herein, a novel B-doped biochar (BBC) was synthesized using waste tea residue and boric acid to activate ammonium persulfate (APS) for efficient degrade quinclorac (QC) in irrigation water. BBC exhibited remarkable catalytic performance for APS, achieving a QC removal efficiency of 91% within 30 min under optimal conditions (0.5 g·L -1 BBC and 0.5 mM APS). The QC degradation efficiency was closely correlated with the BC 2 O groups on BBC, which could enhance electron-transfer between BBC and APS. Quenching experiments and characterization tests confirmed that the electron transfer and 1 O 2 were the main approaches to degrade QC. Seven intermediates of the process of QC degradation were identified, generated mainly by the non-radical ways, and their toxicity was much lower than QC. Pot experiments confirmed that the BBC/APS system can not only alleviate the phytotoxicity of QC but also promote the growth of tobacco. This work provides a new idea and theoretical basis for the removal of herbicide residues using non-metallic biochar for APS activation in the agricultural environments.
摘要：
In recent years, the excessive use of antibiotics has resulted in serious environmental pollution. The accumulation of antibiotics and their metabolites in soil and water not only exacerbates environmental stress, but also poses a direct threat to human health. While biochar-enhanced microbial remediation has emerged as a promising strategy, the targeted regulation of biochar–microbe interactions for optimized antibiotic removal remains underexplored. This study systematically dissects the effectiveness of biochar-regulated enhanced microorganisms for antibiotic removal. By integrating rationality characteristics with functionality features and considering their practical applications across various microorganisms, we have discovered that customized biochar modification can significantly enhance the degradation efficiency of antibiotics by microorganisms. The paper further identifies the targeted regulation measures of biochar as a microbial modulator enhancer, the role of biochar in microorganisms, and the potential application of biochar-regulated enhanced microorganisms in the environment. Finally, it also discusses the challenges and future prospects, providing new insights for addressing antibiotic pollution in the environment.
摘要：
The enrichment efficiency of cadmium (Cd) in biological crusts formed under different environmental conditions varies significantly. However, although extracellular polymeric substances (EPS) are key components in heavy metal removal, the mechanisms by which their content and composition influence the Cd removal capacity of different types of biological crusts remain unclear. Our study revealed distinct differences in EPS composition between mine crusts (MC) and paddy crusts (PC). The extracellular polysaccharide content in MC is 3.02 times higher than that in PC, and the extracellular protein content is 6.56 times higher than that of PC. Therefore, the adsorption capacity of MC for Cd is higher than that of PC in both acidic or neutral environments. The types of monosaccharides and proteins in EPS also varied notably between MC and PC, with the total concentration of monosaccharides in the EPS of MC is higher than that in PC. EPS removal markedly reduced Cd adsorption efficiency in both crust types. While exopolysaccharides in both MC and PC initially adsorb Cd faster, extracellular proteins exhibited greater adsorption capacity due to more available surface sites. Molecular docking simulations further demonstrate that MC extracellular proteins have a higher binding energy with Cd (−3.98 kcal/mol) compared to those in PC (−3.52 kcal/mol). These findings underscored the importance of EPS composition in Cd removal and provided a theoretical basis for optimizing biological crusts to facilitate environmental remediation in metal-contaminated mining and agricultural soils.
The enrichment efficiency of cadmium (Cd) in biological crusts formed under different environmental conditions varies significantly. However, although extracellular polymeric substances (EPS) are key components in heavy metal removal, the mechanisms by which their content and composition influence the Cd removal capacity of different types of biological crusts remain unclear. Our study revealed distinct differences in EPS composition between mine crusts (MC) and paddy crusts (PC). The extracellular polysaccharide content in MC is 3.02 times higher than that in PC, and the extracellular protein content is 6.56 times higher than that of PC. Therefore, the adsorption capacity of MC for Cd is higher than that of PC in both acidic or neutral environments. The types of monosaccharides and proteins in EPS also varied notably between MC and PC, with the total concentration of monosaccharides in the EPS of MC is higher than that in PC. EPS removal markedly reduced Cd adsorption efficiency in both crust types. While exopolysaccharides in both MC and PC initially adsorb Cd faster, extracellular proteins exhibited greater adsorption capacity due to more available surface sites. Molecular docking simulations further demonstrate that MC extracellular proteins have a higher binding energy with Cd (−3.98 kcal/mol) compared to those in PC (−3.52 kcal/mol). These findings underscored the importance of EPS composition in Cd removal and provided a theoretical basis for optimizing biological crusts to facilitate environmental remediation in metal-contaminated mining and agricultural soils.
作者：
Dai, Yu;Bostick, Benjamin C.;Du, Huihui;Gu, Xueyuan;Huang, Guopei;...
期刊：
Geochimica et Cosmochimica Acta,2025年394:393-404 ISSN：0016-7037
通讯作者：
Sun, J
作者机构：
[Liu, Shirong; Liu, Yizhang; Dai, Yu; Huang, Guopei; Ning, Zengping; Liu, Chengshuai; Sun, J; Song, Lei; Sun, Jing] Chinese Acad Sci, State Key Lab Environm Geochem, Inst Geochem, Guiyang 550081, Peoples R China.;[Bostick, Benjamin C.; Dai, Yu] Guizhou Med Univ, Sch Publ Hlth, Key Lab Environm Pollut Monitoring & Dis Control, Minist Educ, Guiyang 550025, Peoples R China.;[Bostick, Benjamin C.; Du, Huihui] Lamont Doherty Earth Observ, POB 1000,61 Route 9W, Palisades, NY 10964 USA.;[Gu, Xueyuan; Du, Huihui] Hunan Agr Univ, Coll Resources & Environm, Changsha 410127, Peoples R China.;[Gu, Xueyuan; Song, Lei] Nanjing Univ, Sch Environm, State Key Lab Pollut Control & Resource Reuse, Nanjing 210023, Peoples R China.
通讯机构：
[Sun, J ] C;Chinese Acad Sci, State Key Lab Environm Geochem, Inst Geochem, Guiyang 550081, Peoples R China.
关键词：
Iron oxides;Micropore;Oxyanionic metals;Polyoxyanions;Adsorption
摘要：
A high specific surface area (SSA) typically signifies a superior adsorption capacity. Nevertheless, minerals with high SSAs tend to possess tiny pores that may not be accessible to relatively large (poly)oxyanionic metals. Herein, we assessed the adsorption of (poly)oxyanionic metals on 2-line and 6-line ferrihydrite and goethite with distinct SSAs and pore geometries. SSA was estimated by BET isotherm using N 2 , while pore geometry was measured by N 2 adsorption isotherms and positron annihilation lifetime spectroscopy. Tungstate and its polymers were chosen as representative (poly)oxyanions. Adsorption experiments were performed with constant mineral surface area, but different contact time, pH, and tungsten concentrations. Unexpectedly, the Langmuir adsorption capacities per unit surface area on 6-line ferrihydrite and goethite were 2–6 and 3–11 times as high as those on 2-line ferrihydrite, respectively. Adsorption on 2-line ferrihydrite was also severely kinetically limited. The varying rates and magnitudes of adsorption were attributed to distinct mineral pore widths: (poly)tungstates could hardly fit within the abundant tiny pores in 2-line ferrihydrite formed by voids between the primary particles/aggregates, but could enter the larger pores in 6-line ferrihydrite and goethite. Consequently, significant decreases of mineral microporosity (<2 nm) were observed following (poly)tungstate adsorption. Tungstate and polytungstate with different hydrated ion radii exhibited similar adsorption behavior, most likely due to the formation of adsorbed polytungstate directly on mineral surface. Our data demonstrate that mineral pore geometry controls the solid-solution partitioning of (poly)oxyanionic metals, which is crucial to comprehend their environmental fate and to mitigate their contamination.
A high specific surface area (SSA) typically signifies a superior adsorption capacity. Nevertheless, minerals with high SSAs tend to possess tiny pores that may not be accessible to relatively large (poly)oxyanionic metals. Herein, we assessed the adsorption of (poly)oxyanionic metals on 2-line and 6-line ferrihydrite and goethite with distinct SSAs and pore geometries. SSA was estimated by BET isotherm using N 2 , while pore geometry was measured by N 2 adsorption isotherms and positron annihilation lifetime spectroscopy. Tungstate and its polymers were chosen as representative (poly)oxyanions. Adsorption experiments were performed with constant mineral surface area, but different contact time, pH, and tungsten concentrations. Unexpectedly, the Langmuir adsorption capacities per unit surface area on 6-line ferrihydrite and goethite were 2–6 and 3–11 times as high as those on 2-line ferrihydrite, respectively. Adsorption on 2-line ferrihydrite was also severely kinetically limited. The varying rates and magnitudes of adsorption were attributed to distinct mineral pore widths: (poly)tungstates could hardly fit within the abundant tiny pores in 2-line ferrihydrite formed by voids between the primary particles/aggregates, but could enter the larger pores in 6-line ferrihydrite and goethite. Consequently, significant decreases of mineral microporosity (<2 nm) were observed following (poly)tungstate adsorption. Tungstate and polytungstate with different hydrated ion radii exhibited similar adsorption behavior, most likely due to the formation of adsorbed polytungstate directly on mineral surface. Our data demonstrate that mineral pore geometry controls the solid-solution partitioning of (poly)oxyanionic metals, which is crucial to comprehend their environmental fate and to mitigate their contamination.
摘要：
Biological soil crusts (BSCs) widely exists in mudflat environment, which is known to be efficient in capturing heavy metals from aqueous solutions; However, their ability to adsorb cadmium (Cd(II)) is limited due to low capacity and selectivity. To address this limitation, manganese ethylenediamine phosphates (MEPs) nanomaterial were incorporated into the BSCs to enhance Cd(II) uptake. The MEPs nanomaterials attached to BSC significantly improved the adsorption capacity, rate, and selection for Cd(II). The adsorption kinetics of Cd(II) by BSCs and BSCs-MEPs was well described by a pseudo-second-order model, with BSCs-MEPs exhibiting a much higher adsorption capacity for Cd(II) (77.00 mg/g) compared to BSCs (55.44 mg/g). The Cd(II) removal by BSCs-MEPs has been accelerated to 2 stages, in which the film diffusion/intraparticle diffusion/chemical reaction participated in the 1st stage. And another stage was dynamic equilibrium process. The adsorption isotherm of BSCs-MEPs demonstrated superior performance for Cd(II) compared to BSCs across a pH range from 2 to 9. Most importantly, even in the presence of high concentration of Na+ or Ca2+ ions, BSCs-MEPs exhibited preferential adsorption for Cd(II), a result not observed with BSCs alone. Analysis of X-ray photoelectron spectroscopy spectra demonstrated that functional groups (-NH2/-COOH/-OH) played an important role in Cd(II) adsorption, while the MEPs attach to BSCs leading to the -NH3+ deprotonation, thus enhanced the BSCs' affinity toward Cd(II). Furthermore, molecular dynamics simulation clearly showed that diffusion coefficients (D) of Cd(II) were much higher than those of Ca2+ in EPS with abundant -NH2, which were responsible for selective adsorption. These findings might provide a valuable approach for treating Cd-contaminated water bodies.
