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1.
Chemosphere ; 283: 131304, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34467944

RESUMO

Herbicides are commonly used globally. However, residual herbicides in soils for ages often result in phytotoxicity and serious yield loss to subsequent crops. In this paper, the multi-walled carbon nanotubes (MWCNTs) were utilized to amend the herbicide polluted soil, and the adsorption performance of herbicides to MWCNTs amended soil was studied. Results indicate efficient alleviation of herbicide-induced phytotoxicity to rice and tobacco due to MWCNTs amendment. When 0.4% MWCNTs were applied, the concentration of sulfentrazone that inhibited the same rice height by 50% (IC50) increased to more than 3 times that of pure soil. When the MWCNTs were used to alleviate the phytotoxicity of quinclorac to tobacco, the MWCNTs not only alleviated the phytotoxicity of quinclorac but also promoted the growth of tobacco. The MWCNTs amended soil significantly increased the adsorption of herbicide to soil than biochar. The soil microbial analysis shows that MWCNTs had no significant effect on soil microbial community diversity, but the long-term exposure to MWCNTs could change the structure of the soil microbial community. Above all, our results highlighted the potential implication of the MWCNTs to ensure crop production by promoting crop growth and reducing the residual bioavailability of herbicides.


Assuntos
Herbicidas , Nanotubos de Carbono , Poluentes do Solo , Adsorção , Herbicidas/análise , Herbicidas/toxicidade , Nanotubos de Carbono/toxicidade , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
2.
Chemosphere ; 283: 131286, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470733

RESUMO

This study compares the differences between the distribution of trace elements and rare-earth elements (REEs) formed under reducing and oxidizing soil conditions during pedogenesis on carbonate bedrock. Terra rossa (TR) soils, representing pedogenesis under oxic conditions, and Cretaceous palaeosols (CP), representing pedogenesis under reducing conditions, were sampled on the Istrian peninsula. They were studied by ICP-MS, ICP-OES, XRF, XRD, sequential extraction and statistical analyses. The differences in trace-element behaviour between the TR and CP stem from different redox conditions, but the most remarkable difference was observed in the behaviour of the REEs. Statistical analyses revealed that in TR soils all the REEs showed a very positive correlation, while in CPs the light REEs and heavy REEs showed an internal, very positive correlation. TR soils have almost twice as much REEs as CPs. This difference is pedogenetic, as both materials have a very similar amount of REEs in the residual fraction. While TR soils have the same amount of REEs in fractions other than the residual fraction, CPs have almost no REEs in these fractions. Different REE patterns obtained from sequential extraction, such as a middle-REE enrichment and a positive Ce anomaly in TR soils and light-REE depletion, heavy-REE enrichment, positive Ce and Eu anomalies in CPs, contributed to an understanding of the redox and pedogenetic processes. This study successfully emphasized the influence of different redox conditions on the behaviour of trace and rare-earth elements during pedogenesis on a carbonate bedrock and the ability of the REEs to track pedogenetic processes.


Assuntos
Metais Terras Raras , Poluentes do Solo , Croácia , Metais Terras Raras/análise , Oxirredução , Solo , Poluentes do Solo/análise
3.
Sci Total Environ ; 792: 148411, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34465037

RESUMO

Biodegradation of soil contaminants may be promoted near plant roots due to the "rhizosphere effect" which may enhance microbial growth and activity. However, the effects of different plant cultivars within a single species on degradation remains unclear. Here, we evaluated the removal of soil total petroleum hydrocarbons (TPHs) by ten different cultivars of tall fescue grass (Festuca arundinacea L.) and their associated rhizosphere microbiomes. TPH removal efficiency across the ten different cultivars was not significantly correlated with plant biomass. Rhizing Star and Greenbrooks cultivars showed the maximum (76.6%) and minimum (62.2%) TPH removal efficiencies, respectively, after 120 days. Significant differences were observed between these two cultivars in the composition of rhizosphere bacterial and fungal communities, especially during the early stages (day 30) of remediation but the differences decreased later (day 90). Putative petroleum-degrading bacterial and fungal guilds were enriched in the presence of tall fescue. Moreover, the complexity of microbial networks declined in treatments with higher TPH removal efficiency. The relative abundances of saprotrophic fungi and putative genes alkB and C12O in bacetria involved in petroleum degradation increased, especially in the presence of Rhizing Star cultivar, and this was consistent with the TPH removal efficiency results. These results indicate the potential of tall fescue grass cultivars and their associated rhizosphere microbiomes to phytoremediate petroleum hydrocarbon-contaminated soils.


Assuntos
Festuca , Microbiota , Petróleo , Poluentes do Solo , Biodegradação Ambiental , Hidrocarbonetos , Solo , Microbiologia do Solo , Poluentes do Solo/análise
4.
Environ Monit Assess ; 193(10): 643, 2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34508279

RESUMO

The soil environment imposes a great influence on human health. Soil heavy metal pollution caused by human activities is an important part of environmental problems in urban areas. Due to an inadequate infrastructure, imperfect management, and intensive human activities, the sources of heavy metals in urban fringe areas are often more complicated than those in other areas, such as mining areas and agricultural irrigation areas. To solve this problem, the first step is to locate the source of pollution. However, the traditional methods of source analysis, such as principal component analysis and positive matrix factorization, always require correlations between elements. This study examined the Hg, Cd, Pb, and Cu contents in the Fengdong District of Xi'an, China, and found that these elements are not correlated in this area. Hence, traditional source analysis methods are not applicable in the study area. In response to this problem, this research proposed a new source analysis method based on Pearson's correlation analysis. The Nemerow index, geoaccumulation index, and ecological risk index were adopted to evaluate soil heavy metal pollution in the study area. Via comparison to the actual situation, it was concluded that the geoaccumulation index is more suitable for source analysis in this area. Through Pearson's correlation analysis, it was found that the geoaccumulation index is significantly correlated with the various land use types. Among them, transportation land exerted a greater impact on Pb pollution, and industrial land exerted a significant impact on the Hg distribution. The Cu distribution was related to construction land, while the Cd distribution was mainly related to urban land and cultivated land. In addition, the demolition of residential areas and abandoned farmlands imposed significant effects on Pb and Cd pollution, respectively.


Assuntos
Metais Pesados , Poluentes do Solo , China , Monitoramento Ambiental , Humanos , Metais Pesados/análise , Medição de Risco , Solo , Poluentes do Solo/análise
5.
Environ Monit Assess ; 193(9): 620, 2021 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-34476613

RESUMO

Potential toxic metals from natural and anthropogenic sources accumulate in soil and plants, and represent important environmental contamination challenges. The ecological and human health risks of the potential toxic metals in rice grain, paddy soil, and rice plants of Omor rice field were assessed. The total metal concentration from the four sampling sections (mg/kg) were soil-Zn (29.51 ± 2.23), Mn (55.27 ± 8.10), Cd (5.49 ± 2.24), Cu (2.94 ± 1.47), Pb (14.35 ± 6.54), and Cr (27.06 ± 8.31); rice grain-Zn (21.70 ± 5.44), Mn (3.30 ± 0.21), Cd (00.14 ± 0.11), Cu (2.80 ± 0.34), Pb (11.98 ± 0.58), and Cr (15.86 ± 2.79); and for rice plant-Zn (5.24 ± 1.93), Mn (4.68 ± 1.91), Cd (0.21 ± 0.11), Cu (4.88 ± 0.61), Pb (15.24 ± 6.16), and Cr (46.5 ± 6.05). The estimated daily intakes for adult showed that Cd and Pb exceeded the safe limit by 1% and 93%, respectively. The metal hazard quotients (Zn-0.0007, Mn-0.00019, Cd-0.16, Cu-0.19, and Cr-0.0000077) were less than 1 indicating no probable health risk originating from their exposure. The total hazard index (0.35) also suggests no probable health risk connected with the rice consumption. The metals' ecological risk indices of the soil showed low-risk (< 40), except Cd in some sections of the rice field which indicated moderate potential ecological risk (40-80).


Assuntos
Metais Pesados , Oryza , Poluentes do Solo , Adulto , China , Monitoramento Ambiental , Humanos , Metais Pesados/análise , Metais Pesados/toxicidade , Nigéria , Medição de Risco , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
6.
Chemosphere ; 282: 130897, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470145

RESUMO

Mussel shell (MS) and biochar (BC) are commonly used for the remediation of metal contaminated soil. However, less research has been focused to examine the efficacy of their combinations to reduce metal toxicity in crop plants. This study was therefore conducted to investigate the effects of BC, MS and their activated concoctions on the soil properties, enzyme activities and nickel (Ni) immobilization in aged Ni contaminated soil. Moreover, the growth, photosynthetic pigments and anti-oxidative machnery of Brassica napus plants has also been investigated in order to determine amendments efficiency in reducing soil Ni toxicity for plants. The results showed that the application of Ni adversely affected soil health and trigged stress responses by inducing oxidative stress in B. napus. However, the incorporation of amendments reduced the bioavailability of Ni, and the concoctions of BC and MS showed promising results in the immobilization of Ni. Among various combinations of BC and MS, treatment with BC + MS (3:1) significantly reduced Ni uptake, decreased reactive oxygen species (ROS) and enhanced antioxidant defense of B. napus plants. Results showed that amendment's combinations stimulated the transcriptional levels of ROS scavenging enzymes and suppressed the expression level of Ni transporters. The morphological and physical characterization techniques (i.e. SEM, BET, EDS, FTIR and X-ray diffraction analyses) showed that amendment's combinations had relatively higher Ni adsorption capacity, indicating that BC and MS concoctions are efficient immobilizing agents for minimizing Ni availability, preventing oxidative toxicity and promoting growth and biomass production in rapeseed plants under metal stress conditions.


Assuntos
Bivalves , Brassica napus , Poluentes do Solo , Animais , Carvão Vegetal , Níquel/análise , Níquel/toxicidade , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
7.
Chemosphere ; 282: 131092, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34470156

RESUMO

Remediation of heavy metal contaminated soil with appropriate washing agents is crucial to the decline in the harmfulness of contaminated soil by heavy metals to the environment and human health. In this study, citric acid (CA) and water-soluble chitosan (WSCS) as natural and degradable washing agents were used to remove Zn in the soil by two-step washing method. Results indicated that the two-step washing with CA and WSCS were found to be suitable for the removal of Zn from the contaminated soils, which significantly decreased the total concentration of Zn in the soil. After the remediation process with two-step soil washing, the contents of Zn in different chemical species decreased, especially for the carbonate-bound fraction. Therefore, the two-step soil washing with CA and WSCS was advisable for the remediation of Zn-contaminated soils. The washing mechanism could include the acid dissolution, ion exchange and complexation reaction between zinc ions and functional groups such as hydroxyl, carboxyl, amine and amide groups. This study provided the theoretical support for the exploitation and application of suitable washing agents used for the remediation of contaminated soils by heavy metals.


Assuntos
Quitosana , Recuperação e Remediação Ambiental , Metais Pesados , Poluentes do Solo , Ácido Cítrico , Humanos , Metais Pesados/análise , Solo , Poluentes do Solo/análise , Água , Zinco
8.
J Hazard Mater ; 416: 125805, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492779

RESUMO

Heavy metal pollution is a worldwide problem affecting the quality of agricultural production and human health. In this study, spent mushroom substrate (SMS) and its compost (CSMS) were used to remedy black soil and red soil with simulated Pb contamination, aiming to discover their role in the improving rhizosphere environment and structuring rhizosphere bacterial community under lead stress. We designed an ultra-small-scale plot experiment to separate the rhizosphere from non-rhizosphere soil when planting water spinach (Ipomoea aquatica Forsk). The results showed that under 600 mg/kg of lead pollution, CSMS and SMS had no significant effect on the rhizosphere bacterial diversity in the black soil, but CSMS significantly increased the rhizosphere bacterial diversity in the red soil. The amendments significantly increased the percentage of Proteobacteria and Bacteroidetes in rhizosphere soil, and the relative abundance of some beneficial genera, such as Pseudoxanthomonas, Rhizomicrobium, Lysobacter etc., which subsequently restructured the bacterial community. The compositions of bacterial community of the red soil remediated by both amendments evolved to those of the black soil.


Assuntos
Rizosfera , Poluentes do Solo , Bactérias/genética , Humanos , Chumbo/toxicidade , Solo , Microbiologia do Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
9.
J Hazard Mater ; 416: 125837, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492794

RESUMO

Paddy soils in southern China are heavily co-polluted by arsenic (As) and cadmium (Cd). The accumulation of these contaminants in rice grains may pose a high health risk. We evaluated the impact of adjusted water management practice (i.e., conventional irrigation and aerobic treatment after heading stage) and the application of two immobilization agents (i.e., CaO and Fe2O3) on the accumulation of As and Cd in rice grains of three rice varieties (i.e., Jinyou-463, Jinyou-268, and Mabayouzhan). The different schemes were tested via conducting a field experiment in paddy soil in Shaoguan, Guangdong Province, China. The results showed that the combined scheme (selecting Jinyou-268, aerobic water management after the heading stage, and 0.09% CaO and 0.5% Fe2O3 amendments) exhibited the best performance in the reduction of As and Cd accumulation in rice grains. This combined scheme decreased the grain As concentration by 26.19% and maintained the Cd at a low level (0.056 mg/kg) as compared to the use of local conventional irrigation patterns. Moreover, health risk assessment demonstrated that by applying the optimal scheme, neither As nor Cd content in rice had carcinogenic risk. However, the grain As remains at a high non-carcinogenic risk. We suggest that future field study design should fully incorporate the uncertainty of the natural environment to make the research conclusions more feasible for popularization and utilization. This study demonstrated an approach of utilizing the synergy effects of various measures for safe rice production in fields subjected to As and Cd contaminations.


Assuntos
Arsênio , Oryza , Poluentes do Solo , Arsênio/análise , Cádmio/análise , China , Solo , Poluentes do Solo/análise
10.
J Hazard Mater ; 416: 125855, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492804

RESUMO

The environment is being polluted in different many with metal and metalloid pollution, mostly due to anthropogenic activity, which is directly affecting human and environmental health. Metals and metalloids are highly toxic at low concentrations and contribute primarily to the survival equilibrium of activities in the environment. However, because of non-degradable, they persist in nature and these metal and metalloids bioaccumulate in the food chain. Genetically engineered microorganisms (GEMs) mediated techniques for the removal of metals and metalloids are considered an environmentally safe and economically feasible strategy. Various forms of GEMs, including fungi, algae, and bacteria have been produced by recombinant DNA and RNA technologies, which have been used to eliminate metal and metalloids compounds from the polluted areas. Besides, GEMs have the potentiality to produce enzymes and other metabolites that are capable of tolerating metals stress and detoxify the pollutants. Thus, the aim of this review is to discuss the use of GEMs as advanced tools to produce metabolites, signaling molecules, proteins through genetic expression during metal and metalloids interaction, which help in the breakdown of persistent pollutants in the environment.


Assuntos
Metaloides , Metais Pesados , Poluentes do Solo , Biodegradação Ambiental , Fungos , Humanos , Poluentes do Solo/análise
11.
J Hazard Mater ; 416: 125869, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492816

RESUMO

Heavy metals (HMs) accumulation in the soils poses risks towards the environment and health. Glomalin related soil protein (GRSP) produced by arbuscular mycorrhizal fungi (AMF) has metal-sorption and soil aggregation properties and is critical in the survival of plants and AMF. For the first time, this study attempted to examine the GRSP mediated bio-stabilization of HMs in soils contaminated with municipal solid wastes (MSW). The content and interrelationship of GRSP and HMs, along with soil physicochemical properties were studied in 20 different soil samples from the dumping site. Higher amount of GRSP indicated potential bio-stabilization of HMs at some sites. GRSP exhibited weak positive correlation with essential (Zn, Cu) and toxic HMs (Cd, Ni). Cr and Mn were possibly sequestered in AMF structures and thus found to be negatively correlated with GRSP. The positive correlation observed between GRSP and soil nutrients like N, P and soil organic carbon (SOC) indicating potential of AMF-GRSP in sustaining soil health. Results revealed that AMF residing at contaminated sites produced higher amount of GRSP potentially to bio-stabilize the HMs, and reduce their bioavailability and also facilitate SOC sequestration.


Assuntos
Metais Pesados , Micorrizas , Poluentes do Solo , Carbono , Resíduos Perigosos , Solo , Poluentes do Solo/análise , Resíduos Sólidos
12.
J Hazard Mater ; 416: 125884, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492822

RESUMO

The acid-extractable fraction Cd(II) in soil accumulates easily in organisms, migrates and transforms in the ecological environment, which has posed potential health risks to human. This study found that the acid-extractable fraction Cd(II) in soil could be released rapidly into water at very low Cd2+ concentration. Carboxylated polypropylene (PP-g-AA) fibers-ball with high selectivity as adsorbent was used in the Cd(II) contaminated soil-water system. It could remove promptly trace Cd2+ from water even in the presence of interfering metal ions. Moreover, Cd(II) desorbed from soil to water could be continuously adsorbed by PP-g-AA fibers-ball, which kept the Cd2+ concentration always at a low level. This forms a dynamic equilibrium of rapid release- selective adsorption toward the acid-extractable fraction Cd(II) in the soil-water system. Here, the migratory pathway for the acid-extractable fraction Cd(II) to be released from contaminated soil to water and adsorbed simultaneously on the surface of PP-g-AA fibers-ball was established. This work offers a novel protocol that can remove more than 90% of the acid-extractable fraction Cd(II) from contaminated soil within 12 h, thereby contributes better to mitigate the risk of Cd(II) from soil to the food chain without changing the physical and chemical properties of soil.


Assuntos
Cádmio , Poluentes do Solo , Adsorção , Cádmio/análise , Humanos , Solo , Poluentes do Solo/análise , Água
13.
J Hazard Mater ; 416: 125886, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492824

RESUMO

In many urban areas, elevated soil lead (Pb) concentrations are indicators of community-level Pb exposure. Here, we examine the spatial distribution and speciation of legacy soil Pb contamination in East Chicago, Ind., an industrial center with a wide range of Pb sources including a former lead smelter. In situ X-ray fluorescence spectroscopy (n = 358) revealed widespread soil Pb contamination above the Environmental Protection Agency regulatory limit for soils. This soil contamination was heterogenous across all neighborhoods, and mostly uncorrelated with distance from the former smelting site. Soil Pb levels increased with decreasing median household income in East Chicago's nine neighborhoods (r = -0.73, p = 0.03). Extended X-ray absorption fine structure spectroscopy (n = 44) indicated that the soil Pb was primarily adsorbed to iron and manganese oxides or humic acids, and as Pb hydroxycarbonate regardless of contamination levels. Crystalline insoluble forms of Pb, like pyromorphite, were not detected in significant concentrations. Thus, the unique chemical forms of potential Pb sources to soil, such as paint, ore and slag are not persistent and instead are extensively repartitioned into acid-soluble forms of Pb with greater bioavailability. These findings have implications for remediation efforts and human health as blood Pb levels in this community are significantly elevated.


Assuntos
Metais Pesados , Poluentes do Solo , Disponibilidade Biológica , Monitoramento Ambiental , Humanos , Chumbo , Metais Pesados/análise , Solo , Poluentes do Solo/análise
14.
J Hazard Mater ; 416: 125894, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492832

RESUMO

The chemistry of root cell wall of rice could be changed by inoculation of arbuscular mycorrhizal fungi (AMF). Hydroponic experiments were conducted to investigate the roles of such changes on cadmium (Cd) uptake and distribution in rice. Results showed that inoculation of AM fungus Rhizophagus intraradices (RI) significantly enhanced (p < 0.05) shoot biomass, plant height and root length of rice, and decreased Cd concentration in shoot and root under Cd stress. Moreover, Cd in root was mainly found in pectin and hemicellulose 1 (HC1) components of root cell wall. Inoculation of RI increased the levels of pectin, HC1 and lignin content, accompanied by the increments of L-phenylalanine ammonia-lyase (PAL) and pectin methylesterase (PME) activities. Results of Fourier transform infrared spectroscopy further showed that more hydroxyl and carboxyl groups in root cell wall were observed in mycorrhizal treatment, compared with control. This study demonstrates that cell wall components could be the locations for Cd fixation, which reduced Cd transportation from root to shoot. Inoculation of AMF may remodel root cell wall biosynthesis and affect the characteristics of Cd fixation. The entering and fixing mechanisms should be further studied.


Assuntos
Micorrizas , Oryza , Poluentes do Solo , Cádmio/análise , Parede Celular/química , Fungos , Raízes de Plantas/química , Poluentes do Solo/análise
15.
J Hazard Mater ; 416: 125898, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492836

RESUMO

Moso bamboo is considered a potential species for heavy metal (HM) phytoremediation; however, the effect of intercropping on rhizosphere and phytoextraction remains to be elucidated. We comparatively investigated rhizobacteria, soil properties, and phytoextraction efficiency of monoculture and intercropping of Moso bamboo and Sedum plumbizincicola in Cu/Zn/Cd-contaminated soil. Compared with monocultures, intercropping increased the bacterial α-diversity indices (Shannon, Chao1) and the number of biomarkers. Intercropping reduced the contents of soil organic matter (SOM), available nutrients, and Cd and Cu in rhizosphere soils, and reduced the Cd and Zn contents in tissues of sedum. By contrast, Cd and Zn contents in tissues of bamboo increased, and the increase of organic acid in root exudates from intercropping could facilitate the HM absorption. The total amount of Cu, Zn, and Cd removed from the soil in intercropping system was 1.2, 1.9, and 1.8 times than those in monoculture bamboo, respectively. The abundances of Proteobacteria, Acidobacteria, Verrucomicrobia and Actinobacteria were higher in intercropping, playing an important role in soil nutrient cycles and HM remediation. These bacterial communities were closely correlated (P < 0.01) with SOM, available nitrogen, available phosphorus, and HMs. The results suggested this intercropping pattern can increase HM removal efficiency from polluted soils.


Assuntos
Metais Pesados , Poluentes do Solo , Biodegradação Ambiental , Cádmio/análise , Metais Pesados/análise , Rizosfera , Solo , Poluentes do Solo/análise
16.
Environ Monit Assess ; 193(10): 646, 2021 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-34518941

RESUMO

To explore the spatial heterogeneity of pH and cadmium (Cd) content in the soils of the tea gardens in the plateau mountain regions as well as its driving factors, the pH values, Cd content and other physical and chemical indicators from 423 soil samples were examined. A coefficient of variation method and a semivariance function model was adopted to explore the soils' spatial heterogeneity, and a random forest approach was applied to evaluate the factors influencing environmental Cd under different pH values. The results show that the pH values of the soils of the tea gardens in the plateau mountain regions were within the appropriate range for the growth of tea plants, and soil samples with pH values falling between 4.5 and 6.0 account for 74% of all samples. A comparison against the criteria of risk screening values for the contamination of agricultural land, a component of quantifying soil environmental quality in China, was preformed; it was determined that the content of heavy metal Cd in the soil of the tea gardens did not exceed the limit. The content of soil pH in the research area gradually declined from southwest to northeast, exhibiting two distinct parallel distribution zones running along the southwest-northeast direction. The spatial distribution of the heavy metal Cd content in the soil showed a gradually decreasing trend from north to south, with low-value polygons dominantly appearing in the southeasternmost area and high-value polygons concentrated in the north. When the soil pH ≤ 5.5, it had the largest effect on the Cd content; when 5.5 < pH ≤ 6.5, the physical indicators in soil had a relatively larger impact on the Cd content.


Assuntos
Metais Pesados , Poluentes do Solo , Cádmio/análise , China , Monitoramento Ambiental , Concentração de Íons de Hidrogênio , Metais Pesados/análise , Solo , Poluentes do Solo/análise , Chá
17.
Environ Monit Assess ; 193(10): 655, 2021 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-34532779

RESUMO

Heavy metals' pollution of agricultural soil is an environmental problem of widespread concern, especially in China, but, how to accurately identify their sources is still a great challenge. Here, we implemented a high-density sampling strategy (2194 samples collected) and combined correlation analysis (CA), principal component analysis (PCA), positive matrix factorization (PMF) modeling, and geostatistical analyses to identify and quantify the source contributions of heavy metals in agricultural soil in a key commodity grain base of China. The results showed that the excess risk rate of Cd was the highest (4.3%), and contributing to 42.7% of the total potential ecological risk in the region. Hence, Cd is the most important ecological risk factor. Heavy metals in the region mainly originated from oil extraction and smelting (7.5%), parent materials and traffic emissions (59.2%), coal-related industrial activities (11.6%), and agricultural sources (21.7%). Cd was mainly derived from oil extraction and smelting (90.1%). As (73.6%), Cr (90.3%), and Pb (67.1%) were closely associated with parent materials and traffic emissions. Hg (87.7%) was mainly originated from coal-related industrial sources. In addition, As (25.6%) and Pb (24.3%) were also from agricultural sources (such as fertilizer, pesticides, and manure). This study confirms that the combination of these methods can accurately identify the sources of heavy metals in agricultural soil. These findings can assist governmental agencies in implementing targeted control strategies to prevent the spread of heavy metals.


Assuntos
Metais Pesados , Poluentes do Solo , China , Monitoramento Ambiental , Metais Pesados/análise , Análise de Componente Principal , Medição de Risco , Solo , Poluentes do Solo/análise
18.
J Hazard Mater ; 416: 125916, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492849

RESUMO

Cadmium (Cd) pollution in paddy soil seriously endangers food safety production. To investigate the effects and microbiological mechanisms of calcium-magnesium-phosphate (CMP) fertilizer application on Cd reduction in rice, field experiments were conducted in Cd-contaminated paddy soil. Compared with conventional compound fertilizer, CMP fertilizer treatments inhibited Cd uptake through plant roots, significantly decreasing Cd content in rice grains from 0.340 to 0.062 mg/kg. Soil pH and total Ca, Mg and P contents increased after CMP fertilizer application, resulting in a further decrease in soil available Cd content from 0.246 to 0.181 mg/kg. Specific extraction analysis recorded a decrease in both available Fe content and the ratio of nitrate to ammonium nitrogen, indicating that the soil Fe-N cycle was affected by the addition of CMP fertilizer. This finding was also recorded using soil bacterial community sequencing, with CMP fertilizer promoting the progress of nitrate-dependent Fe-oxidation driven by Thiobacillus (1.60-2.83%) and subsequent dissimilatory nitrate reduction to ammonium (DNRA) driven by Ignavibacteriae (1.01-1.92%); Fe-reduction driven by Anaeromyxobacter (3.09-2.23%) was also inhibited. Our results indicate that CMP fertilizer application regulates the Fe-N coupling cycle driven by the soil microbial community to benefit remediation of Cd contaminated paddy soil.


Assuntos
Microbiota , Oryza , Poluentes do Solo , Cádmio/análise , Cádmio/toxicidade , Cálcio , Fertilizantes/análise , Ferro , Óxido de Magnésio , Nitrogênio , Fosfatos , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
19.
J Hazard Mater ; 416: 125921, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492853

RESUMO

In-situ stabilization has been considered an effective way to remediate metal contaminated soil. Thus, pot experiments were undertaken to investigate the effectiveness of multiple stabilization agents such as biochar (BC), mussel shell (MS), zeolite (ZE) and limestone (LS) on the immobilization of Ni, physicochemical features and enzyme activities in polluted soil. Results showed that the sole application of Ni adversely affected the rapeseed growth, photosynthetic pigments, and antioxidative defense. However, the addition of amendments to the contaminated soil significantly reduced Ni bioavailability. The XRD analysis confirmed the formation of Ni related ligands and FTIR showed the presence of hydroxyl, carboxyl and sulfur functional groups, as well as complexation and adsorption of Ni on amendments. Among multiple amendments, biochar significantly enhanced plant biomass attributes and total chlorophyll content. Moreover, addition of amendments also strengthened the antioxidant defense by decreasing Ni induced oxidative stress (H2O2 and O2.-), increased macronutrient availability, reduced Ni uptake and improved soil health. The qPCR analysis showed that the Ni transporters were significantly suppressed by amendments, which is correlated with the lower accumulation of Ni in rapeseed. The present study showed that immobilizing agents, especially biochar, is an effective amendment to immobilize Ni in soil, which restricts its entry into the food chain.


Assuntos
Brassica napus , Poluentes do Solo , Carvão Vegetal , Peróxido de Hidrogênio , Níquel/análise , Estresse Oxidativo , Solo , Poluentes do Solo/análise
20.
J Hazard Mater ; 416: 125942, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492869

RESUMO

A novel Ralstonia Bcul-1 strain was isolated from soil samples that was closest to Ralstonia pickettii. Broad-spectrum resistance was identified to a group of heavy metal ions and tolerance to concentrations of Cd2+ up to 400 mg L-1. Low concentrations of heavy metal ions did not have distinctive impact on heavy metal resistance genes and appeared to induce greater expression. Under exposure to Cd2+, cell wall components were significantly enhanced, and some proteins were also simultaneously expressed allowing the bacteria to adapt to the high Cd2+ living environment. The maximum removal rate of Cd2+ by the Ralstonia Bcul-1 strain was 78.97% in the culture medium supplemented with 100 mg L-1 Cd2+. Ralstonia Bcul-1 was able to survive and grow in a low nutrient and cadmium contaminated (0.42 mg kg-1) vegetable soil, and the cadmium removal rate was up to 65.76% in 9th growth. Ralstonia Bcul-1 mixed with biochar could maintain sustainable growth of this strain in the soil up to 75 d and the adsorption efficiency of cadmium increased by 16.23-40.80% as compared to biochar application alone. Results from this work suggests that Ralstonia Bcul-1 is an ideal candidate for bioremediation of nutrient deficient heavy metal contaminated soil.


Assuntos
Metais Pesados , Poluentes do Solo , Biodegradação Ambiental , Cádmio/toxicidade , Metais Pesados/toxicidade , Ralstonia , Solo , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
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