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1.
J Environ Qual ; 49(5): 1359-1369, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33016446

RESUMO

Cadmium concentrations in cacao (Theobroma cacao L.) beans from South America often exceed trade limits. Liming soil is advocated as a remediation option, but amendments cannot be incorporated into the entire root zone without harming the trees. An experiment was set up to identify how Cd uptake varies within the root zone when surface and subsurface soil layers are either limed or not. The experiment used 22-cm-height pots with top and bottom layers using surface and subsurface soil samples from a cacao field. The potted soils were either surface limed or not or fully limed and layers spiked with stable 108 Cd isotope in various combinations to trace the plant Cd provenance. The root distribution was neither affected by liming nor by soil source; 70% of the root biomass was present in the top layer. Plants grown on the fully limed surface soil had 1.7 times lower Cd concentrations in leaves than the unlimed treatments, whereas this concentration was 1.2 times lower when only the top layer was limed (surface soil used in both layers). The isotope dilution data showed that surface soil liming enhanced Cd uptake from the unlimed bottom layer compared with the unlimed soil, suggesting compensating mechanisms. The pots containing surface soil over subsurface soil also showed that compensating effect but, due to lower phytoavailable Cd in the subsurface soil, surface liming still effectively reduced foliar Cd. We conclude that liming might be a feasible mitigation strategy, but its effectiveness is limited when Cd phytoavailability remains untreated in the subsurface layer.


Assuntos
Cacau , Poluentes do Solo/análise , Cádmio/análise , Plântula/química , Solo
2.
J Environ Qual ; 49(4): 1054-1061, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33016482

RESUMO

Cadmium (Cd) can accumulate in soil from the application of phosphorus fertilizer. However, there is little information on what happens to soil Cd concentrations when Cd inputs stop. This study used soil and pasture samples collected from a long-term field trial to measure changes in Cd concentrations in soil for 22 yr after Cd inputs from fertilizer had stopped and assessed whether the application of nitrogen (N) (50 kg ha-1  yr-1 ) could increase plant uptake of Cd and reduce soil Cd concentrations. It was found that there was no significant change in total or labile soil Cd (1 M CaCl2 extractable) concentrations after Cd inputs stopped. The application of N did not significantly (P < .05) increase dry matter yield or increase Cd solubility. As a result, N did not enhance plant uptake of Cd. A mass balance that included Cd loss via plant uptake and Cd leaching confirmed they were insufficient to result in a detectable decrease in soil Cd concentration over the 22-yr interval of the trial. It appears that even an acid soil with low amounts of carbon (2.67%), iron/aluminum oxides, and clay can still strongly retain Cd, preventing Cd depletion from the soil, despite stopping Cd inputs and trying to enhance plant uptake of Cd from the application of N fertilizer.


Assuntos
Fertilizantes/análise , Poluentes do Solo/análise , Cádmio/análise , Fósforo , Solo
3.
Ecotoxicol Environ Saf ; 203: 110961, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888621

RESUMO

Cadmium (Cd), which seriously affects plant growth and crop production, is harmful to humans. Previous studies revealed ryegrass (Lolium multiflorum Lam.) exhibits Cd tolerance, and may be useful as a potential hyperaccumulator because of its wide distribution. In this study, the physiological and transcriptional responses of two ryegrass cultivars [i.e., high (LmHC) and low (LmLC) Cd tolerance] to Cd stress were investigated and compared. The Cd tolerance of LmHC was greater than that of LmLC at various Cd concentrations. The uptake of Evans blue dye revealed that Cd-induced root cell mortality was higher in LmLC than in LmHC after a 12-h Cd treatment. Furthermore, the content and influx rate of Cd in LmLC roots were greater than in LmHC roots under Cd stress conditions. The RNA sequencing and quantitative real-time PCR data indicated that the Cd transport regulatory genes (ABCG37, ABCB4, NRAMP4, and HMA5) were differentially expressed between the LmLC and LmHC roots. This expression-level diversity may contribute to the differences in the Cd accumulation and translocation between LmLC and LmHC. These findings may help clarify the physiological and molecular mechanisms underlying ryegrass responses to Cd toxicity. Additionally, ryegrass may be able to hyperaccumulate toxic heavy metals during the phytoremediation of contaminated soil.


Assuntos
Adaptação Biológica , Cádmio/metabolismo , Lolium/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Poluentes do Solo/metabolismo , Transcrição Genética/efeitos dos fármacos , Adaptação Biológica/efeitos dos fármacos , Adaptação Biológica/genética , Biodegradação Ambiental , Cádmio/análise , Cádmio/toxicidade , Genes de Plantas , Lolium/química , Lolium/genética , Raízes de Plantas/química , Raízes de Plantas/genética , Poluentes do Solo/análise , Poluentes do Solo/toxicidade
4.
Chemosphere ; 254: 126799, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957268

RESUMO

Enrichment of cadmium (Cd) during weathering and pedogenesis of carbonate rocks has resulted in large areas of lands with soil Cd concentrations exceeding the official guidelines in China and other countries. However, it is reported in many studies that the risk of soil contamination by Cd from this natural process can be neglected as most of the Cd is not bioavailable. Noticing that the previous studies focused only on eluvial areas but not on lowland alluvium, where Cd from the eluvial areas can be transported and accumulated, we selected the Qingyang county in Anhui province, where there are two small drainage basins developed wholly on carbonate bedrock, to compare the Cd speciation and activity between eluvium and alluvium, and to evaluate the risk of Cd pollution to the latter. By the application of systematic sampling and analysis of the bedrock, soil, and rice grain samples, and in comparison with the previously acknowledged "high background with low mobility" area in Guizhou, it was found that soil developed from alluvium has both higher total Cd and higher mobile Cd proportion than soil from the upland eluvium. A very high percentage of rice grain samples (51%) grown on the alluvial soil exceeded the food standard for Cd (0.2 mg kg-1). Therefore, the spatial division of alluvium and eluvium should be the first step in the assessment of the Cd risk in carbonate regions, and special attention should be given to soil developed from alluvium.


Assuntos
Cádmio/análise , Poluentes do Solo/análise , Carbonatos/análise , China , Poluição Ambiental/análise , Poluição Ambiental/estatística & dados numéricos , Oryza , Solo , Tempo (Meteorologia)
5.
Environ Monit Assess ; 192(10): 651, 2020 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-32964290

RESUMO

Cadmium (Cd) pollution in plastic shed soils has become increasingly severe, posing a great threat to human health and social stability. Phytoremediation of cadmium pollution is an environmentally friendly and inexpensive remediation method. In this study, maize (Zea mays L.) was selected as the phytoremediation crop by a potted method, and the bioavailability of cadmium was investigated by adding exogenous elemental sulfur. The relationships among the sulfur content, maize growth, cadmium accumulation, and soil parameters were systematically studied. The results showed that, with the supplement of sulfur, the soil pH and activities of soil enzymes (urease, catalase, and sucrase) decreased gradually, and the available heavy metals (Cd, Cr, Zn, and Cu) in soil showed an upward trend. The optimal cadmium enrichment was achieved under T2 by increasing both the biomass of the maize plant and the cadmium concentration in roots and stems. However, T3 and T4 significantly inhibited the growth of maize roots and shoots, leading to a much lower plant biomass compared with that of CK (sulfur-free treatment) and T2. In addition, the cumulative cadmium was not increased because of the low accumulation of cadmium in some parts of the plant. Correlation analyses showed that the sulfur content was negatively correlated with soil pH and maize biomass (P < 0.01), and the cadmium content of whole maize was positively correlated with the dry weight of maize (P < 0.05) and the cadmium content in roots and stems (P < 0.01). In summary, to optimize cadmium phytoremediation of the plastic shed soil, an appropriate concentration of sulfur should be selected in practical applications to ensure that the biomass of the maize is maximized, and the cadmium concentration in different parts of the maize is increased or stabilized.


Assuntos
Cádmio/análise , Poluentes do Solo/análise , Biodegradação Ambiental , Biomassa , Monitoramento Ambiental , Humanos , Raízes de Plantas/química , Plásticos , Solo , Enxofre , Zea mays
6.
Bull Environ Contam Toxicol ; 105(4): 639-644, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32955595

RESUMO

Arsenic (As) and cadmium (Cd) are common soil pollutants whose opposing geochemical behaviors must be taken into account in the development of cost-effective, environmentally friendly remediation strategies. In this study, a pot experiment with lettuce and a field experiment with wheat were performed to examine the impacts of zeolite, biochar, MnO2, zero-valent iron (ZVI) individually and in binary combinations thereof on As-Cd pollution. The results of the pot experiment showed that biochar, MnO2 and ZVI had good passivation effects on As and Cd when provided individually, but the effects of a combination of 0.2% ZVI/0.5% biochar or 0.2% MnO2/0.5% ZVI were even better. These amendments were further investigated in a field experiment, which confirmed the positive effect of 0.2% MnO2/0.5% ZVI. Therefore, ZVI/biochar and MnO2/ZVI mixtures may offer effective solutions to the remediation of farmland soil contaminated with both As and Cd.


Assuntos
Arsênico/química , Cádmio/química , Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/química , Arsênico/análise , Cádmio/análise , Carvão Vegetal , Poluição Ambiental , Fazendas , Ferro , Alface , Compostos de Manganês , Óxidos , Solo , Poluentes do Solo/análise , Triticum
7.
Environ Monit Assess ; 192(9): 583, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32803620

RESUMO

In this study, a new analytical strategy was developed to determine trace cadmium in aqueous samples with high sensitivity and accuracy. A combination of magnetic nickel nanoparticles (Ni-MNPs) based dispersive solid-phase extraction (DSPE) and flame atomic absorption spectrometry fitted with a slotted quartz tube (SQT-FAAS) lowered the detection limit of cadmium. The magnetic Ni nanoparticles were synthesized, characterized, and thoroughly optimized in a stepwise approach. The quartz tube was custom cut in the laboratory to suit the specifics of the flame burner. Using the optimized conditions, a limit of detection value of 0.58 µg/L and limit of quantification value of 1.93 µg/L were obtained. To demonstrate accuracy and applicability of the developed method, well water samples were analyzed for their Cd content, and matrix effect on the extraction yield was investigated. The percent recovery results calculated ranged from 93.8 to 108.2%, with corresponding standard deviation values ranging from 1.7 to 7.7. These results established the developed method as sensitive, accurate, and precise for determination of cadmium at trace levels.


Assuntos
Microextração em Fase Líquida , Poluentes Químicos da Água/análise , Cádmio/análise , Monitoramento Ambiental , Fenômenos Magnéticos , Quartzo , Extração em Fase Sólida , Espectrofotometria Atômica
8.
Sci Total Environ ; 738: 140339, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-32806342

RESUMO

Studies have demonstrated the role of acanthocephalan as environmental bioindicators. The dynamics in the parasite-host relationship that define the patterns of distribution of trace metals in parasites and, in its host, are extremely variable. In addition, the neotropical region, which is a major maintainer of the biodiversity of fish and parasites, remains little explored in this subject. Therefore, our objective was to analyze and compare the concentration of Cadmium (Cd) in the tissues of Prochilodus lineatus and Serrasalmus marginatus collected from Baía and Paraná rivers, as well as to assess the use of acanthocephalan as environmental bioindicators of pollution and their Cd bioaccumulation capacity. We collected 53 fish, 20 specimens of Prochilodus lineatus from Paraná River and 17 from Baía River, in addition to 16 specimens of Serrasalmus marginatus from Baía River, in September 2017 and March 2018. Tissues of the fish along with their parasites were subjected a Cd concentration analysis by Atomic Absorption Spectroscopy. The results revealed that the parasites had higher concentrations than all the tissues of S. marginatus, P. lineatus from Baía River and Paraná River. The high Cd concentrations in these parasites derived from their bioaccumulation capacity, because of the absorption of nutrients directly from the intestinal content of the fish through the tegument, as well as for the presence of Cd on the surface waters of Praná River floodplain. Besides that, the Coefficient of Spearman Rank Correlation showed that the infrapopulation size seems to affect Cd bioaccumulation in the parasites, smaller infrapopulations demonstrate a higher accumulation capacity compared to the larger ones. With that, we concluded that the two acanthocephalans species analyzed in this study have a good capacity for Cd accumulation, and can be used as accumulation indicators of trace-metal pollution. Accumulation indicators provide important information on the biological availability of pollutants.


Assuntos
Caraciformes , Parasitos , Animais , Brasil , Cádmio/análise , Biomarcadores Ambientais , Monitoramento Ambiental , Rios
9.
Sci Total Environ ; 738: 139832, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-32806361

RESUMO

Labile soil Cd is susceptible to changes over space and time due to the physical and chemical properties of the soil as well as biological processes. In this study, non-disruptive, in situ monitoring was used to explore these changes. We analyzed the mechanism(s) by which Cd is morphologically transformed and its migration patterns, with the goal of preventing soil Cd from becoming labile. The results showed that the concentration of labile Cd in the soil exhibited spatiotemporal variability throughout the rice growth period. Over time, it increased and then declined, while over space, the concentration of labile Cd in rhizosphere is higher than that in non-rhizosphere. As the depth increased, the concentration of Cd increased and then declined, especially during the flowering stage. The change of soil labile Cd concentration showed significant negative correlation with the change in soil pH and easy dynamic S(II) and Fe(II) content. It was also found that root action changed the pH of the soil during rice growth, thereby affecting the morphologies of S(II) and Fe(II), which governed the transformation of Cd and its soil mobility.


Assuntos
Oryza , Poluentes do Solo/análise , Cádmio/análise , Rizosfera , Solo
10.
Sci Total Environ ; 738: 140311, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-32806385

RESUMO

Trace element concentrations in the rhizosphere were quantified to better understand why soil liming often fails to reduce cadmium (Cd) uptake by plants. Maize seedlings were grown on a soil with natural background levels of Cd and zinc (Zn). Soil liming increased soil pH from 4.9 to 6.5 and lowered the soil solution free ion activities by factor 7 (Cd) and 9 (Zn). In contrast, shoot Cd concentrations were unaffected by liming while shoot Zn concentrations were lowered by factor 1.9. Mapping of labile soil trace elements using diffusive gradients in thin films (DGT) in combination with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) revealed an almost complete depletion of Cd in the rhizosphere in all soil treatments, showing that Cd uptake is controlled by diffusion. The flux of Cd from soil to the DGT, with direct contact between the soil and the binding gel, was unaffected by liming whereas it decreased by factor 3 for Zn, closely mimicking the contrasting effects of liming on Cd and Zn bioavailability. This evidence, combined with additional flux data of freshly spiked Cd and Zn isotopes in soil and with modelling, suggests that the diffusive transport of Cd in unsaturated soil is more strongly controlled by the labile adsorbed metal concentration than by its concentration in solution. This is less the case for Zn because of its inherently slower desorption compared to Cd.


Assuntos
Poluentes do Solo/análise , Oligoelementos , Cádmio/análise , Rizosfera , Solo , Zea mays , Zinco/análise
11.
Environ Pollut ; 265(Pt B): 115029, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32806453

RESUMO

Environmental complexity leads to differences in the spatial distribution of heavy metal pollution in soil and rice. Such spatial differences will seriously affect the safety of planted rice and can impact regional management and control. How to scientifically reveal these spatial differences is an urgent problem. In this study, the spatial mismatch relationship between Cd pollution in soil and rice grains (brown rice) was first explored by the interpolation method. To further reveal the causes of these, the specific recognition rules of the spatial relationship of Cd pollution were extracted based on a decision tree model, and the results were mapped. The results revealed a spatial mismatch in Cd pollution between the soil and rice grains in the study area, and the main results are as follows: (i) slight soil pollution and safe rice accounted for 68.88% of the area; (ii) slight soil pollution and serious rice pollution accounted for 13.39% of the area and (iii) safe soil and serious rice pollution accounted for 11.63% of the area. In addition, 11 recognition rules of Cd spatial pollution relationship between soil and rice were proposed, and the main environmental factors were determined: SOM (soil organic matter), Dis-residence (distance from residential area), soil pH and LAI (leaf area index). The average accuracy of rule recognition was 75.90%. The study reveals the spatial mismatch of heavy metal pollution in soil and crops, providing decision-making references for the spatial accurate identification and targeted prevention of heavy metal pollution spaces.


Assuntos
Oryza , Poluentes do Solo/análise , Cádmio/análise , Árvores de Decisões , Monitoramento Ambiental , Poluição Ambiental/análise , Solo
12.
Ecotoxicol Environ Saf ; 202: 110913, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800248

RESUMO

Soil is considered as a sink for heavy metals. Human health is severely affected by the continuous intake of toxic heavy metals even in a very low concentration. In the present experiment, we determined the influence of nutritional status including control (fasted condition), glucose (fed state), plant protein (fed state), animal protein (fed state) and calcium (fed state) on soil cadmium (Cd) and copper (Cu) bioaccessibility using physiologically-based extraction test (PBET) method together with simulator of the human intestinal microbial ecosystem (SHIME) model. The bioaccessibility of Cd was 1.06-73.58%, 0.44-54.79% and 0-17.78% and Cu was 3.81-67.32%, 4.98-71.14%, and 0-17.54% in the phase-I, phase-II and Phase-III respectively (in this study gastric phase, small intestinal phase and colon phase were considered as phase-I, phase-II and Phase-III respectively). The outcomes showed that, the average Cd bioaccessibility was higher with animal protein addition compared with other treatments in different phases. So, the effect of animal protein on Cd bioaccessibility was higher than other treatments in the phase-I, phase-II and phase-III. Due to the addition of plant protein, the higher average bioaccessibility of Cu was noticed in phase-I and phase-II in comparison to other treatments. However, in phase-III, the higher average bioaccessibility of Cu was found due to control treatment comparing with other treatments. Therefore, the influence of plant protein was higher than other nutrients on Cu bioaccessibility in the phase-I and phase-II. Moreover, other nutrients showed variable influence on Cd and Cu bioaccessibility. So, nutritional status has a significant effect on bioaccessibility as well as human health risk assessment.


Assuntos
Cádmio/análise , Cobre/análise , Poluentes do Solo/análise , Ecossistema , Monitoramento Ambiental/métodos , Poluição Ambiental , Humanos , Intestinos/química , Metais Pesados , Nutrientes , Solo
13.
Bull Environ Contam Toxicol ; 105(2): 283-290, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32734360

RESUMO

The current study investigated the efficiency of sepiolite (SE), sodium humate (HS), microbial fertilizer (JF) and SE combined with JF/HS in a ratio of 2:1 (w/w) (JF-2SE and HS-2SE) on Cd, Pb and As bioavailability in field trials with rice (Oryza sativa L.). The results showed that all the amendments remarkably decreased (p < 0.05) the contents of available Cd and available Pb in soil. Only JF-2SE treatment reduced available As concentration in soil. All the amendments were found to effectively reduce (p < 0.05) the contents of As in brown rice. Both JF-2SE and HS-2SE co-applications reduced the concentrations of Cd in brown rice to 0.108 and 0.135 mg kg-1, and that of Pb reduced to 0.2 and 0.175 mg kg-1, which met the national standard limit of China. Thus, the co-application of JF/HS-2SE can be a promising remediation strategy in Cd, Pb and As co-contaminated paddy soil.


Assuntos
Cádmio/química , Recuperação e Remediação Ambiental/métodos , Chumbo/química , Poluentes do Solo/química , Disponibilidade Biológica , Cádmio/análise , China , Poluição Ambiental , Fertilizantes , Chumbo/análise , Silicatos de Magnésio , Oryza , Solo/química , Poluentes do Solo/análise
14.
Environ Pollut ; 266(Pt 2): 115196, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32771840

RESUMO

The characterization of DOM and its effect on heavy metal solubility in soils have been widely concerned, while few concerns on the phytostabilization of multi-metal contaminated soils. A pot experiment was performed to characterize dissolved organic matter (DOM) in the rhizosphere of the mining ecotype (ME) and non-mining ecotype (NME) of Athyrium wardii (Hook.) when exposed to Cd and Pb simultaneously, and investigate its effect on Cd and Pb solubility in soils. The ME presented more DOM in the rhizosphere when exposed to Cd and Pb simultaneously than that exposed to single Cd or Pb, and also than the NME. The acid fractions (hydrophilic acid, hydrophobic acid) and hydrophilic fractions (hydrophilic acid, hydrophilic neutral, and hydrophilic base) were the dominant parts of DOM in the ME rhizosphere. The ME presented more acid and hydrophilic fractions in the rhizosphere when exposed to Cd and Pb simultaneously. Meanwhile, there were more O-H, C-O, N-H and C-H, assigned to carboxylic groups, phenolic groups, hydroxyl groups, and/or amino groups, present in DOM from the rhizosphere of ME when exposed to Cd and Pb simultaneously. These results highlighted the acid characteristics of DOM in the rhizosphere of ME when exposed to Cd and Pb simultaneously. DOM in the rhizosphere of ME thereby showed greater complexation degree for Cd (68%) and Pb (77%), thus showing greater ability to enhance Cd and Pb solubility in soils when exposed to Cd and Pb simultaneously. This is thereby considered to be one of the key processes for enhancing Cd and Pb uptake by the ME when exposed to Cd and Pb simultaneously.


Assuntos
Poluentes do Solo/análise , Traqueófitas , Cádmio/análise , Chumbo , Rizosfera , Solo
15.
Environ Pollut ; 266(Pt 1): 115371, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32818669

RESUMO

Soil contamination with cadmium (Cd) has become a serious problem, adversely affecting food safety and human health. Effective methods are urgently needed to alleviate toxicity of Cd in plants. In this study, a nine-week continuous pot experiments was conducted to explore the effectiveness of the different nano iron oxide (α-Fe2O3, γ-Fe2O3, Fe3O4) alone and combined with biochar in muskmelon grown on a Cd-contaminated soil. The antioxidant system, chlorophyll, soluble protein, other physiological indexes of muskmelon leaves and the distribution of Cd in matrix soil, leaves and fruit were detected. The results showed that Cd was readily absorbed by plants and caused oxidative stress on plants, while biochar, α-Fe2O3 nanoparticles (NPs) and their mixture group (BFe1 group) could significantly improve it. Specifically, the three treatments reduced the Cd content of the fruit by 19.51-78.86%, reduced the Cd content of leaves by 15.44-36.23% and 22.36-31.77% in weeks 3 and 5, respectively. For the activity of enzymes, three treatments decreased superoxide dismutase (SOD) activity and catalase (CAT) activity by 3.41-38.57% and 24.27-30.33% in week 7, respectively. So BFe1 group application immobilized Cd in soil and reduced Cd partitioning in the aboveground tissues. Overall the combination of biochar and α-Fe2O3 NPs can alleviate Cd toxicity in muskmelon and can protect human beings from Cd exposure.


Assuntos
Cádmio/análise , Poluentes do Solo/análise , Carvão Vegetal , Óxidos , Solo
16.
Environ Pollut ; 266(Pt 1): 115408, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32829173

RESUMO

Phytoextraction using Celosia argentea Linn. can potentially decontaminate Cd-contaminated soils. However, most earlier studies have been conducted at laboratory scale and for a relatively short remediation period. To evaluate the phytoextraction efficiency of C. argentea combined with different soil amendments (ammonium chloride, Bacillus megaterium, and citric acid), an 18-month field experiment was carried out in a farmland soil contaminated with 3.68 mg kg-1 Cd by mine tailings in southern China. Soil Cd concentrations were decreased by 6.34 ± 0.73% after the three harvestings (with no amendments), which was 2.27 times that of the no-planting control (p < 0.05). Application of ammonium chloride, B. megaterium, and citric acid increased the overall Cd reduction rate in soil by 40.5%, 46.1%, and 105%, respectively. The application of citric acid decreased total Cd in soil by up to 16.9% in the rhizosphere soil and 13.0% in the bulk soil. The highest annual shoot biomass yield and Cd extraction amount reached 8.79 t ha-1 and 273 g ha-1. Acid-soluble Cd fraction in the rhizosphere was significantly lower compared to that in the bulk soil (p < 0.05), which indicates that mobile Cd in the rhizosphere was taken up by the roots vastly. C. argentea phytoextraction also improved soil metabolic functions by increasing the activities of soil enzymes (urease, invertase, phosphatase, and catalase). These findings demonstrate that Cd phytoextraction using C. argentea with the application of soil amendments can greatly improve the quality of Cd-contaminated soils.


Assuntos
Celosia , Poluentes do Solo/análise , Biodegradação Ambiental , Cádmio/análise , China , Solo
17.
Bull Environ Contam Toxicol ; 105(3): 428-432, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32740744

RESUMO

The accumulation of Cd and Pb in rice grains poses a potential threat to human health, which is a subject of increasing concern across the globe. We examined the effect that foliar spraying of Zn-ethylenediaminetetraacetate (Zn-EDTA) (0.3% and 0.5% w/v) during the early-grain filling stage has on rice grain yield and Cd, Pb, Zn and Fe contents in rice tissues via a field experiment. The grain yield significantly decreased with the foliar application of 0.5% Zn-EDTA. In rice grain, foliar spraying of 0.5% Zn-EDTA significantly decreased the Cd and Pb contents, but increased the Zn and Fe contents. The main reasons for the decrease in the Cd and Pb content in grain were the inhibition of Cd and Pb by roots and the increased Fe content in grain via Zn-EDTA application. The foliar spraying of Zn-EDTA decreased the grain yield and Cd and Pb contents, while increased the Zn and Fe contents in grains.


Assuntos
Cádmio/análise , Ácido Edético/química , Chumbo/análise , Oryza/fisiologia , Poluentes do Solo/análise , Grão Comestível/química , Humanos , Oryza/efeitos dos fármacos , Folhas de Planta/química , Raízes de Plantas/química , Solo , Zinco/análise
18.
Bull Environ Contam Toxicol ; 105(3): 397-404, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32747993

RESUMO

Sensitivity of tropical freshwater microalgae (Mesotaenium sp., Chlorococcum sp. and Scenedesmus sp.) to environmentally relevant concentrations of hexavalent chromium (Cr6+) and cadmium (Cd2+) was compared individually in three growth media viz. Bold's Basal Medium (BBM), Test Medium 1 (TM1) and Test Medium 2 (TM2) based on fluorescence reduction. Free metal content of growth media was determined by Visual MINTEQ (version 3.1). After 24 h, relative fluorescence of microalgae in the three media decreased with increased metal concentration showing a concentration dependent graded toxicity response. All microalgae were more sensitive to the metals when grown in TM1, when compared, more sensitive to Cr6+ than Cd2+. Metal speciation indicated that TM1 and TM2 media have higher percentage of bioavailable Cd2+ than BBM, and chromium was present mainly as CrO42- and HCrO4-. The results suggest that the TM1 medium is more suitable under short term exposure of microalgae to metals in environmental monitoring.


Assuntos
Cádmio/toxicidade , Cromo/toxicidade , Microalgas/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Cádmio/análise , Cromo/análise , Meios de Cultura , Monitoramento Ambiental/métodos , Água Doce , Scenedesmus , Poluentes Químicos da Água/análise
19.
Sci Total Environ ; 746: 141248, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32745865

RESUMO

There are large areas of moderately Cd-contaminated rice paddies (Cd content was less than risk intervention value) in southwest China, under natural conditions, the effect of irrigation water system's distribution on the Cd contamination in soil and rice is still less accurate. In this study, a survey of paired soil-rice (n = 1520) samples was conducted in a large paddy of about 7000 ha in southwest China that originated from the same parent material and grew with the same rice varieties. Specially, three representative characteristic regions (area A, B, C) were selected from north to south to thoroughly investigate the reasons for pollution characteristics. Background soil, irrigation water and sediment, atmospheric deposition, fertilizer were sampled to study the causes of pollution. Results showed the biological accumulation factor (BAF = C (rice Cd)/C (soil Cd)) of area C in the south reached 1.34, which was about 8 times higher than that of area A in the north. The uneven distribution of irrigation water due to geographical reasons was the most important factor leading to this pollution characteristics. The Cd content in soil of north was much higher than that in the south due to the history of Cd-contaminated irrigation and background content of Cd. During farmland formation, river impinges resulted in a gradual decrease in both Cd content and pH in the background soil from north to south. Both of historical polluters and major irrigation systems were distributed in area A. However, when sewage irrigation stopped about 30 years ago, long-term weakly alkaline irrigation increased the pH of the soil from acidic to neutral in area A. Meanwhile, flooding irrigation in area A reduced the absorption of Cd by roots compared area C where was rarely flooded during the rice planting process due to the lack of irrigation water.


Assuntos
Oryza , Poluentes do Solo/análise , Cádmio/análise , China , Solo
20.
Bull Environ Contam Toxicol ; 105(2): 325-331, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32647963

RESUMO

The objectives of this study was to diagnose Cd and Pb contamination in soil and to identify the main factors that contribute to the transfer of these elements to tomato plants and fruits and contamination levels of the fruits in tropical mountain conditions. Contamination of the study area soils by Cd and Pb was verified. This contamination stemmed from the intensive use of agricultural inputs, mainly organic fertilizers and soluble mineral fertilizers. The relief of the terrain and inadequate soil management influenced the spatial distribution of these two metals. The Cd concentration in tomato fruits was very low, but the Pb contamination detected in approximately 80% of the fruit samples was considerably higher than the limits that pose a danger to human health. The translocation of Pb to the tomato fruits was associated with the use of organic fertilizer, mainly poultry litter.


Assuntos
Cádmio/análise , Chumbo/análise , Lycopersicon esculentum/química , Poluentes do Solo/análise , Agricultura , Fertilizantes/análise , Frutas/química , Humanos , Metais Pesados/análise , Minerais , Solo , Fator de Transferência
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