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1.
Environ Pollut ; 254(Pt B): 113112, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31479811

RESUMO

Antimony, as the Sb(V) species, often occurs in oxic soils and sediments as coprecipitates with poorly-crystalline Fe(III)-bearing minerals. It is common for these Sb(V)-Fe(III) coprecipitates to also contain varying quantities of co-occurring humic acid (HA). When exposed to reducing conditions, the production of Fe(II) may cause the initial metastable HA-Sb(V)-Fe(III) phases to undergo rapid transformations to more stable phases, thereby potentially influencing the geochemical behavior of coprecipitated Sb(V). However, little is known about the impacts of this transformation on the mobility and speciation of Sb. In this study, we reacted synthetic HA-Sb(V)-Fe(III) coprecipitates (Fe:Sb ratio = 4, and C:Fe molar ratios = 0, 0.3, 0.8 and 1.3) with 0, 1 or 10 mM Fe(II) under O2-free conditions at pH 7.0 for 15 days. Fe K-edge EXAFS spectroscopy revealed that solid-phase Fe(III) in the initial coprecipitates contained a mixture of ∼4/5 ferrihydrite (Fe10O14(OH)2) and ∼1/5 tripuhyite (FeSbO4), regardless of the corresponding amount of coprecipitated HA. Tripuhyite persisted throughout the full experiment duration, while ferrihydrite was partially replaced by goethite (FeOOH) when either 1 or 10 mM Fe(II)aq was added to the coprecipitates. The greatest level of goethite formation (∼55% of solid-phase Fe) was observed in the HA-free/10 mM Fe(II)aq treatment, with ferrihydrite transformation being partially attenuated at higher levels of HA. Mobilisation of aqueous Sb was the greatest for 1 mM Fe(II) treatments at high HA:Fe ratios. Sb K-edge XANES spectroscopy showed that the largest reduction of Sb(V) to Sb(III) (∼37%) and the greatest repartitioning of Sb to the mineral surface (∼7.9-9.8%) occurred in the coprecipitates with the highest HA contents in the presence of 10 mM Fe(II). The results indicate that the amount of HA in HA-Sb(V)-Fe(III) coprecipitates can greatly influence mobility and speciation of Sb in Fe(II)-rich conditions. The results of this study provide new insights into alterations in Sb mobility and retention in response to Fe cycling under organic matter-rich reducing conditions.


Assuntos
Antimônio/química , Compostos Férricos/química , Compostos Ferrosos/química , Substâncias Húmicas , Poluentes do Solo/química , Compostos de Ferro/química , Minerais/química , Oxirredução , Espectroscopia por Absorção de Raios X
2.
Ying Yong Sheng Tai Xue Bao ; 30(9): 3245-3251, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31529900

RESUMO

Biochar, with high degree of carbon stability, is considered as a kind of carbon sequestration material that can effectively alleviate the greenhouse effect. It is of great significance for carbon sequestration and mitigation to develop biochar with high carbon retention and stability. Mineral modification can regulate the stability of biochar. However, the relevant research has not received enough attention, and the underlying mechanism is not very clear. Firstly, the evaluation indices of biochar stability were summarized, mainly including H/C atomic ratio, O/C atomic ratio, coefficient of stability R50, volatile-matter content, thermal weight loss rate of carbon, carbon (chemical) oxidation loss rate, and cumulative CO2 emission of microbial mineralization. Then, based on the analysis of impact factors of biochar stability (such as raw material type, carbonization condition, external environment, etc.), we reviewed research progress about the effects of mineral modification on biochar stability. Furthermore, possible mechanisms of both enhancement and weakening effects on biochar stability were put forward. Enhancement is mainly due to the effects of physical barrier of minerals and the organic mineral complex formed by the interaction of mineral and biochar. While weakening effect is mainly due to special mineral composition, such as the Fe-bearing mineral composition, which promotes the thermal decomposition of biochar at high temperature. Finally, future research directions were proposed, in order to promote the development of carbon sequestration technology of biochar and provide technical support and theoretical basis for obtaining more stable biochar.


Assuntos
Carvão Vegetal/química , Minerais/química , Solo , Sequestro de Carbono
3.
Environ Sci Pollut Res Int ; 26(25): 25945-25957, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31273653

RESUMO

During the operation of a mine, waste rock is often deposited in heaps and usually left under ambient conditions allowing sulfides to oxidize. To focus on waste rock management for preventing acid rock drainage (ARD) formation rather than ARD treatment could avoid its generation and reduce lime consumption, costs, and sludge treatment. Leachates from 10 L laboratory test cells containing sulfide-rich (> 60% pyrite) waste rock with and without the addition of lime kiln dust (LKD) (5 wt.%) were compared to each other to evaluate the LKD's ability to maintain near neutral pH and reduce the sulfide oxidation. Leaching of solely waste rock generated an acidic leachate (pH < 1.3) with high concentrations of As (21 mg/L), Cu (20 mg/L), Fe (18 g/L), Mn (45 mg/L), Pb (856 µg/L), Sb (967 µg/L), S (17 g/L), and Zn (23 mg/L). Conversely, the addition of 5 wt.% LKD generated and maintained a near neutral pH along with decreasing of metal and metalloid concentrations by more than 99.9%. Decreased concentrations were most pronounced for As, Cu, Pb, and Zn while S was relatively high (100 mg/L) but decreasing throughout the time of leaching. The results from sequential extraction combined with element release, geochemical calculations, and Raman analysis suggest that S concentrations decreased due to decreasing sulfide oxidation rate, which led to gypsum dissolution. The result from this study shows that a limited amount of LKD, corresponding to 4% of the net neutralizing potential of the waste rock, can prevent the acceleration of sulfide oxidation and subsequent release of sulfate, metals, and metalloids but the quantity and long-term stability of secondary minerals formed needs to be evaluated and understood before this method can be applied at a larger scale.


Assuntos
Compostos de Cálcio/química , Poeira/análise , Ferro/química , Metaloides/análise , Óxidos/química , Sulfatos/química , Sulfetos/análise , Concentração de Íons de Hidrogênio , Metaloides/química , Metais/análise , Metais/química , Minerais/análise , Minerais/química , Oxirredução , Sulfetos/química
4.
Orig Life Evol Biosph ; 49(1-2): 19-47, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31302843

RESUMO

Pyrite and organic matter closely coexist in some hydrothermally-altered gabbroic xenoliths from the Hyblean Plateau, Sicily. The representative sample consists of plagioclase, Fe-oxides, clinopyroxene, pyrite and minor amounts of many other minerals. Plagioclase displays incipient albitization, clinopyroxene is deeply corroded. Pyrite grains are widely replaced by spongy-textured magnetite, which locally hosts Ca-(and Fe-)sulfate micrograins and blebs of condensed organic matter. Whole-rock trace element distribution evidences that incompatible elements, particularly the fluid-mobile Ba, U and Pb, are significantly enriched with respect to N-MORB values. The mineralogical and geochemical characteristics of the sample, and its U-Pb zircon age of 216.9 ± 6.7 MA, conform to the xenolith-based viewpoint that the unexposed Hyblean basement is a relict of the Ionian Tethys lithospheric domain, mostly consisting of abyssal-type serpentinized peridotites with small gabbroic intrusions. Circulating hydrothermal fluids there favored the formation of hydrocarbons trough Fischer-Tropsch-type organic synthesis, giving also rise to sulfidization episodes. Subsequent variations in temperature and redox conditions of the system induced partial de-sulfidization, Fe-oxides precipitation and sulfate-forming reactions, also promoting poly-condensation and aromatization of the already-formed hydrocarbons. Here we show organic matter adhering to a crystal face of a microscopic pyrite grain. Pyrite surfaces, as abiotic analogues of enzymes, can adsorb and concentrate organic molecules, also acting as catalysts for a broad range of proto-biochemical reactions. The present data therefore may support established abiogenesis models suggesting that pyrite surfaces carried out primitive metabolic cycles in suitable environments of the early Earth, such as endolithic recesses in mafic rocks permeated by hydrothermal fluids.


Assuntos
Evolução Química , Ferro/química , Minerais/química , Compostos Orgânicos/química , Sulfetos/química , Sicília
5.
Chemosphere ; 235: 670-678, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31276880

RESUMO

Extracellular DNA (eDNA) is widely present in soil, with potential ecological impacts. Metal cations are naturally present on the surface of soil clay minerals, although the adsorption mechanism of eDNA on clay minerals saturated with metal cations is still not fully understood. The research investigated the adsorption of eDNA, using salmon sperm DNA as a representative, on metal cation (Na+, Ca2+, and Fe3+)-saturated montmorillonites (Mt). Metal cation-saturated Mt have higher adsorption capacities for DNA. Compared with Mt (3500 mg⋅kg-1), the amounts of DNA adsorption on metal cation-saturated Mt (pH = 7.0) were increased by 0.74-5.38 times, and followed the descending order of Fe-Mt > Na-Mt > Ca-Mt > Mt. A temperature of 25 °C was found to be more suitable than 15 and 35 °C for DNA adsorption, while an increasing pH value (3.0-9.0) reduced DNA adsorption on Mt and metal cation-saturated Mt. Microscopic and spectroscopic analyses, together with a model computation technique, confirmed that metal cations saturated on the surface of Mt work like a "cation bridge" linking oxygen atoms in the phosphate groups of DNA and the negatively charged moieties of Mt, which were predominantly bound through electrostatic forces, thus, facilitating DNA adsorption at pH > 5. The results of this investigation provide valuable insight into eDNA adsorption on soil clay minerals and the transport and fate of eDNA in the natural soil environment.


Assuntos
Bentonita/química , DNA/química , Metais/química , Poluentes do Solo/química , Adsorção , Silicatos de Alumínio/química , Cátions/química , Argila , Minerais/química , Fosfatos , Sódio , Solo
6.
Bull Environ Contam Toxicol ; 103(2): 330-335, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31263937

RESUMO

The immobilization effect and mechanism of nano-hydroxyapatite(NHAP) on Pb in the ryegrass rhizosphere soil were studied by root-bag experiment. The speciation analysis results revealed that the residual Pb concentrations in the rhizosphere soil significantly increased after NHAP application. The acid-soluble and reducible Pb concentrations significantly decreased, indicating that NHAP had obviously immobilized Pb. Meanwhile, NHAP significantly promoted the secretion of tartaric acid from ryegrass roots, resulting the rhizosphere soil pH had been below that of the control group. This helped to relieve the stress of Pb on ryegrass, also promoted the dissolution of NHAP, resulting the formation of stable precipitation with more Pb ions. NHAP increased the rhizosphere soil pH by 0.03 to 0.17, which promoted the conversion of Pb to non-utilizable bioavailability. The total Pb mass balance indicated only a very small proportion Pb transferred to the shoots through ryegrass roots. The formation of pyromorphite by Pband NHAP in soil was accordingly to interpret the dominant mechanism for Pb immobilization.


Assuntos
Durapatita/química , Chumbo/análise , Lolium/crescimento & desenvolvimento , Nanoestruturas/química , Rizosfera , Poluentes do Solo/análise , Adsorção , Disponibilidade Biológica , Concentração de Íons de Hidrogênio , Chumbo/metabolismo , Lolium/metabolismo , Minerais/química , Modelos Teóricos , Fosfatos/química , Raízes de Plantas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo , Solo/química , Poluentes do Solo/metabolismo , Tartaratos/metabolismo
7.
Environ Pollut ; 253: 171-180, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31306824

RESUMO

In order to exhaustively investigate the physical and chemical mechanisms of heavy metal immobilization in sludge incineration residue (SIR)-based magnesium potassium phosphate cement (MKPC), this work investigated the influence of Pb2+ and Zn2+ on the compressive strength and microstructure of SIR-based MKPC, and the efficiency of Pb and Zn immobilization. Taking the difference of Ksp (solubility product) of different heavy metal compounds as the entry point, the physical and chemical mechanisms of Pb and Zn immobilization, and the competitive mechanism between coexisting ions, were comprehensively analyzed. It was discovered that Pb2+ is in the form Pb3(PO4)2, and Zn2+ is immobilized in the form Zn2(OH)PO4 [Zn3(PO4)2 is preferentially formed, when the pH > 7, Zn3(PO4)2 is converted to Zn2(OH)PO4]. The low solubility of heavy metal phosphates is the main reason that Pb2+ and Zn2+ are well immobilized. The preferential formation of Pb3(PO4)2 (Ksp = 8 × 10-43) and Zn3(PO4)2 (Ksp = 9.0 × 10-33) reduced the amount of MgKPO4·6H2O (Ksp = 2.4 × 10-11), resulting in a decrease in compressive strength. Besides, coexisting Pb2+ and Zn2+ has a competitive effect: Pb2+ will weaken the immobilization efficiency of Zn2+. The new exploration of these mechanisms provide a theoretical basis for rationally adjusting the Magnesia/Phosphate ratio to enhance the compressive strength and improve the efficiency of heavy metals immobilization.


Assuntos
Incineração/métodos , Chumbo/química , Zinco/química , Materiais de Construção , Íons , Magnésio , Compostos de Magnésio , Metais Pesados/química , Minerais/química , Fosfatos/química , Potássio , Compostos de Potássio , Esgotos/química
8.
Environ Pollut ; 254(Pt A): 112924, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31362254

RESUMO

The long-term use of animal manure in agriculture has resulted in estrogen pollution, which poses risks to facility vegetable soils. Owing to the complex soil composition, estrogen may exhibit a variety of behaviors at the water/soil interface. This study demonstrated the role of humic acid (HA) on the 17ß-estradiol (E2) adsorption by clay minerals (montmorillonite, kaolinite, and hematite). The interfacial behaviors were investigated using adsorption kinetics and isotherms data. Then, the effects of temperature, pH, and bisphenol A (BPA) on the interactions between humic-mineral complexes and E2 were explored. The adsorption of E2 is an exothermic and spontaneous process, and the addition of HA to minerals significantly promoted their E2 adsorption capacities. Higher pH levels (>10) and the presence of BPA decreased the adsorption capacities of minerals and mineral complexes for E2. Moreover, intercalation, hydrophobic partitioning, π-π interactions and hydrogen bonding could dominate the E2 adsorption onto complexes. These results provided insight into the interfacial behaviors of E2 on the surfaces of humic-mineral complexes and promoted the understanding of the migration and transport of estrogens in soils.


Assuntos
Compostos Benzidrílicos/química , Estradiol/química , Fenóis/química , Adsorção , Bentonita/química , Argila , Substâncias Húmicas/análise , Concentração de Íons de Hidrogênio , Caulim/química , Cinética , Minerais/química , Solo , Temperatura Ambiente , Água/química
9.
Environ Sci Pollut Res Int ; 26(25): 25725-25732, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31267388

RESUMO

The tailings produce acid mine drainage (AMD) due to sulfide minerals, especially pyrite oxidation. AMD has caused serious pollution to the surrounding aquatic and terrestrial ecosystems because of its famous low pH value and high metal and sulfate concentration, which is an urgent environmental problem faced by the world's ore mining industry. Here, we show that silicic protective surface films can suppress the oxidation of pyrite-bearing tailings for AMD control at-source without pre-oxidation of pyrite and solution pH adjuster and buffer. We found that the silicic protective surface films formed by calcium silicate can inhibit the oxidation of pyrite-bearing tailings and reduce the production of AMD through chemical leaching tests. Fourier transform infrared (FTIR) analyses and scanning electron microscopy with energy-dispersive spectrometry (SEM/EDS) confirmed the presence of silicic protective surface films of calcium silicate on the surface of pyrite-bearing tailings.


Assuntos
Ácidos/química , Ferro/química , Metais/química , Minerais/química , Sulfatos/análise , Sulfetos/análise , Ecossistema , Mineração , Oxirredução , Sulfatos/química , Sulfetos/química
10.
Chemosphere ; 233: 896-904, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31340417

RESUMO

Understanding the distribution of PFOS isomers between the aqueous phase and goethite is crucial, since it is an abundant sorbent and thus may have a large influence on the mobility of PFOS. This study was conducted to understand the effects of pH, humic acid (HA), fulvic acid (FA) and sulfate on sorption of PFOS isomers. The results will increase the understanding about what parameters may control the fate and transport of PFOS in surface and ground water. The study was conducted by adding PFOS spiked water to a goethite slurry with different aqueous chemistry. Levels of total PFOS and PFOS isomers were quantified using an Ultra-Performance Liquid Chromatograph coupled to a triple quadrupole mass spectrometer. Results showed that sorption of PFOS was mainly dependent on pH; sorption decreased as pH increased. Presence of HA increased log Kd from 1.29 to 2.03, 1.76 to 1.92 and 1.51 to 1.96 at pH 5.50-7.50 for 3-/4-/4-PFOS, 6-/2-PFOS and L-PFOS, respectively. Changes in the aqueous chemistry also affected the behaviour of PFOS as the addition of Na2SO4 enhanced the sorption of PFOS. Results showed that L-PFOS was more readily sorbed to goethite at pH < 4.35 both in the presence and in the absence of humic or fulvic acids. At pH > 4.5 the 3-/4-/5-PFOS isomer group was more associated to goethite. Besides electrostatic interactions, which controlled the sorption of PFOS, this study indicate that the presence of dissolved humic substances in the aqueous phase enhances the sorption via hydrophobic mechanisms.


Assuntos
Ácidos Alcanossulfônicos/química , Benzopiranos/química , Fluorcarbonetos/química , Água Subterrânea/química , Substâncias Húmicas/análise , Compostos de Ferro/química , Minerais/química , Sulfatos/química , Poluentes Químicos da Água/química , Adsorção , Concentração de Íons de Hidrogênio , Interações Hidrofóbicas e Hidrofílicas
11.
Plant Dis ; 103(9): 2367-2373, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31318645

RESUMO

Sugarcane yellow leaf virus (SCYLV), the causal agent of yellow leaf, is widespread in Florida. Two field trials were set up, one on organic soil and one on mineral soil, to investigate the rate and timing of sugarcane infection by SCYLV under field conditions and the effect of the virus on yield. Each trial consisted of plots planted with healthy or SCYLV-infected seed cane of two commercial cultivars. Virus prevalence varied from 83 to 100% in plots planted with infected seed cane regardless of cultivar, location, and crop season. On organic soil, plants of virus-free plots became progressively infected in plant cane and first ratoon crops. On mineral soil, healthy sugarcane became initially infected in the first ratoon crop. After three crop seasons, the highest SCYLV prevalence rates were 33 and 7% on organic and mineral soils, respectively. No significant negative effect of SCYLV on yield was found in plant cane crop regardless of cultivar and soil type. However, yield reductions in ratoon crops varied from nonsignificant to 27% depending on cultivar and soil type. Low virus prevalence observed after three crop seasons suggested that planting virus-free seed cane should limit the impact of SCYLV on sugarcane production in Florida.


Assuntos
Luteoviridae , Saccharum , Solo , Florida , Luteoviridae/fisiologia , Minerais/química , Doenças das Plantas/virologia , Saccharum/virologia , Solo/química
12.
Nat Commun ; 10(1): 2670, 2019 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-31209248

RESUMO

Illitisation requires potassium incorporation into a smectite precursor, a process akin to reverse weathering. However, it remains unclear whether microbes facilitate K+ uptake to the sediments and whether illitisation was important in the geological past. The 2.1 billion-year-old Francevillian Series of Gabon has been shown to host mat-related structures (MRS) and, in this regard, these rocks offer a unique opportunity to test whether ancient microbes induced illitisation. Here, we show high K content confined to illite particles that are abundant in the facies bearing MRS, but not in the host sandstone and black shale. This observation suggests that microbial biofilms trapped K+ from the seawater and released it into the pore-waters during respiration, resulting in illitisation. The K-rich illite developed exclusively in the fossilized MRS thus provides a new biosignature for metasediments derived from K-feldspar-depleted rocks that were abundant crustal components on ancient Earth.


Assuntos
Bactérias/metabolismo , Sedimentos Geológicos/química , Potássio/metabolismo , Água do Mar/química , Tempo (Meteorologia) , Biofilmes , Terra (Planeta) , Fósseis , Gabão , Sedimentos Geológicos/análise , Minerais/análise , Minerais/química , Potássio/análise , Silicatos/química
13.
Int J Nanomedicine ; 14: 3929-3941, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31213809

RESUMO

Introduction: Hierarchical nanofibrous scaffolds are emerging as a promising bone repair material due to their high cell adhesion activity and nutrient permeability. However, the existing method for hierarchical nanofibrous scaffolds fabrication is complicated and not perfectly suitable for further biomedical application in view of both structure and function. In this study, we constructed a hierarchical nanofibrous poly (l-lactic acid)/poly(ε-caprolactone) (PLLA/PCL) scaffold and further evaluated its bone healing ability. Methods: The hierarchical PLLA/PCL nanofibrous scaffold (PLLA/PCL) was prepared by one-pot TIPS and then rapidly mineralized at room temperature by an electrochemical deposition technique. After electrode-positioning at 2 V for 2 hrs, a scaffold coated with hydroxyapatite (M-PLLA/PCL) could be obtained. Results: The pore size of the M-PLLA/PCL scaffold was hierarchically distributed so as to match the biophysical structure for osteoblast growth. The M-PLLA/PCL scaffold showed better cell proliferation and osteogenesis activity compared to the PLLA/PCL scaffold. Further in vivo bone repair studies indicated that the M-PLLA/PCL scaffold could accelerate defect healing in 12 weeks. Conclusion: The results of this study implied that the as-prepared hydroxyapatite coated hierarchical PLLA/PCL nanofibrous scaffolds could be developed as a promising material for efficient bone tissue repair after carefully tuning the TIPS and electrodeposition parameters.


Assuntos
Regeneração Óssea/fisiologia , Galvanoplastia/métodos , Minerais/química , Nanofibras/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico/farmacologia , Tecidos Suporte/química , Fosfatase Alcalina/metabolismo , Animais , Adesão Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Eletricidade , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Células-Tronco Mesenquimais/ultraestrutura , Osteogênese/efeitos dos fármacos , Porosidade , Ratos Sprague-Dawley , Crânio/diagnóstico por imagem , Crânio/efeitos dos fármacos , Crânio/patologia , Fatores de Tempo , Engenharia Tecidual/métodos , Microtomografia por Raio-X
14.
J Sci Food Agric ; 99(14): 6227-6233, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31250922

RESUMO

BACKGOUND: Potato peels are usually discarded before consumption of the tubers. However, it could be expected that red- and purple-fleshed potato peels contain more minerals. Therefore, the purpose of the study was to evaluate and compare the proximate and mineral composition in flesh and peels of six coloured potato cultivars. Five proximate compositions (dry matter, total soluble solids, protein, fibre, and ash) and nine minerals [phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), iron (Fe), zinc (Zn), copper (Cu), Boron (B), manganese (Mn)] content were determined. The data obtained were evaluated employing the multivariate analysis techniques: principal component analysis and hierarchical cluster analysis. RESULTS: The results show that proximate and mineral composition depends on potato tissue and cultivar. Potato peels have significantly higher levels of protein, fibre, ash and minerals (except Mg) than the flesh. However, flesh contains the highest contents of dry matter and total soluble solids. Of the studied elements, K has the highest content in both parts of the potato tuber followed by P, Mg, Ca, Fe, Zn, B, Mn, and Cu. Violetta peels had the highest contents of ash, K and Mg, and Highland Burgundy Red peels had the highest protein, fibre, Ca, Mn contents. The flesh of the Highland Burgundy Red cultivar shows the highest contents of dry matter and total soluble solids. CONCLUSION: Based on the present study, it can be concluded that the investigated red and purple potato peels showed significantly higher protein, fibre, ash and element (K, Ca, Mg, P, Fe, Cu, Zn, Mn, B) contents compared to the flesh. © 2019 Society of Chemical Industry.


Assuntos
Minerais/química , Tubérculos/química , Cor , Cobre/análise , Ferro/análise , Magnésio/análise , Manganês/análise , Fósforo/análise , Potássio/análise , Solanum tuberosum/metabolismo , Zinco/análise
15.
Environ Sci Pollut Res Int ; 26(24): 24922-24932, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31243660

RESUMO

The effects of low-molecular-weight organic acids (LMWOAs) on the transport of graphene oxide nanoparticles in saturated kaolinite- and goethite-coated sand columns were studied. Acetic acid, glycolic acid, malonic acid, and tartaric acid were chosen in the experiments. LMWOAs enhanced the mobility of GO by electrostatic/steric repulsion. In addition, they competed with GO for limited deposition sites on grain surfaces. The effects of organic acids on the transport of GO strongly depended on organic acid species. In general, the transport enhancement effects followed the order of tartaric acid > malonic acid > glycolic acid > acetic acid; this difference may be related to the number and type of functional groups of organic acids. Different LMWOAs enhanced the transport of GO in goethite-coated sand to a larger extent than did in kaolinite-coated sand under the test conditions; this was likely related to the differences of physicochemical characteristics between goethite and kaolinite. Organic acids significantly inhibited the deposition of GO at 0.5 mM Ca2+; this was possible that Ca2+ enhanced adsorption of organic acids by complexing with the surface O-functionalities of both LMWOAs and sand grain. Consequently, more organic acid molecules competed with GO for deposition sites on grain surfaces. Additionally, a two-site transport model was used to fit the transport data. Our findings have important implications for the understanding of the deposition and fate of GO in soil especially in rhizosphere environments where various low-molecular-weight organic acids are active.


Assuntos
Ácidos Carboxílicos/química , Grafite/análise , Nanopartículas/análise , Poluentes do Solo/análise , Adsorção , Grafite/química , Compostos de Ferro/química , Caulim/química , Minerais/química , Peso Molecular , Nanopartículas/química , Dióxido de Silício/química , Solo/química , Poluentes do Solo/química , Eletricidade Estática
16.
Environ Sci Pollut Res Int ; 26(23): 23292-23304, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31197671

RESUMO

Improving soil quality, reducing waste, and mitigating climate change require an understanding of the balance between soil organic carbon (SOC) accumulation and depletion after the application of different quantities of fungal residue and chemical fertilizers. We evaluated the mineralized carbon (MC) content and mineralization rate (MR) after nine applications of chemical fertilizers (C) and fungal residue (F) in paddy fields, at rates of 0, 50, and 100%. A double exponential model was used to calculate the potential rates of MC and SOC turnover. The combined application of fungal residue and chemical fertilizers led to significantly higher MC and MR, by 24.97-100.05 and 24.36-98.07%, respectively, during 57 days of incubation than that of the control. The MC and MR values were highest with the C50F100 treatment. Simulations with the double exponential model showed that both the active SOC pools (C1) and potential SOC mineralization flux C1 + C2 were highest with C50F100, and the MR constants, k1 and k2, were highest with C100F100. The potential SOC MR [(C1 + C2) / SOC] was highest with C50F100. The application of fungal residue and chemical fertilizers to paddy fields effectively alleviated soil acidification caused by chemical fertilizers and increased the nutrient content, MC, MR, C1, and C1 + C2 of soils. However, the over-use of fungal residue or chemical fertilizers produces the reverse effects. Therefore, appropriate quantities of chemical fertilizers and fungal residue need to be applied to enhance the carbon sequestration capacity of soils while improving the MC and MR.


Assuntos
Agricultura/métodos , Sequestro de Carbono , Carbono/química , Fertilizantes/análise , Minerais/química , Solo/química , China , Oryza/crescimento & desenvolvimento
17.
Environ Sci Pollut Res Int ; 26(23): 23923-23936, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31222654

RESUMO

This paper determines the impact of two clay minerals (kaolinite and montmorillonite) and three oxides (goethite, δ-MnO2, and bayerite) on the elemental composition and FTIR spectra of humic-like acid (HLA) extracted from microbial-mineral residue formed from the microbial utilization of lignin in liquid shake flask cultivation. Goethite, bayerite, and δ-MnO2 showed higher enrichment capabilities of C and O + S in the HLA than kaolinite and montmorillonite. Goethite showed the highest retention of organic C, followed by bayerite, but kaolinite exhibited the least exchangeability. Kaolinite and montmorillonite enhanced microbial consumption of N, resulting in the absence of N in HLA. A few aliphatic fractions were preferentially gathered on the surfaces of kaolinite and montmorillonite, making the H/C ratios of HLA from the clay mineral treatments higher than those of HLA from the oxide treatments. δ-MnO2 was considered the most effective catalyst for abiotic humification, and goethite and bayerite ranked second and third in this regard. This trend was proportional to their specific surface areas (SSAs). However, comparing the effects of different treatments on the promotion of HLA condensation by relying solely on the SSA of minerals was not sufficient, and other influencing mechanisms had to be considered as well. Additionally, Si-O-Al and Si-O of kaolinite participated in HLA formation, and Si-OH, Si-O, and Si-O-Al of montmorillonite also contributed to this biological process. Fe-O and phenolic -OH of goethite, Mn-O of δ-MnO2, and Al-O of bayerite were all involved in HLA formation through ligand exchange and cation bridges. Lignin was better protected from microbial decomposition by the kaolinite, bayerite, and δ-MnO2 treatments, which caused lignin-like humus (HS) formation. Under the treatments of δ-MnO2, goethite, and bayerite, HLA showed a greater degree of condensation compared to HLA precipitated by kaolinite and montmorillonite. Contributions from Si-O, and Si-O-Al of clay minerals, and Fe-O, Mn-O, and Al-O of oxides were the mechanisms by which minerals catalyzed the formation of HS from lignin.


Assuntos
Bentonita/química , Compostos de Ferro/química , Caulim/química , Lignina/química , Minerais/química , Argila , Substâncias Húmicas , Fenóis , Solo
18.
Environ Sci Pollut Res Int ; 26(23): 23505-23523, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31197673

RESUMO

Bacteria-derived biochars from Bucillus sp. biomass under different pyrolysis temperature (250 °C, 350 °C, 450 °C, and 550 °C, respectively) were prepared, forming polyptychial, mesoporous graphite-like structure. The adsorption and sequestration efficiencies of Cd2+ by these biochars were evaluated, and the underlying mechanisms were then discussed. Cd2+ sorption data could be well described by Langmuir mode while the pseudo-second-order kinetic model and Elovich model best fitted the kinetic data. The functional groups complexation, cation-π interactions, and interaction with minerals (including surface precipitation with phosphorus and ion exchange) jointly contributed to Cd2+ sorption and sequestration on biochar, but the interaction with minerals played a dominant role by forming insoluble cadmium salt composed by polycrystalline and/or amorphous phosphate-bridged ternary complex. The maximum sorption capacity of BBC350 in simulated water phase of soil for Cd2+ was 34.6 mg/g. Furthermore, the addition of bacteria-derived biochars (1%, w/w) decreased the fractions easily absorbed by plants for Cd in the test paddy soils by 1.9-26% in a 10-day time. Results of this study suggest that bacteria-derived biochar would be a promising functional material in environmental and agricultural application.


Assuntos
Cádmio/química , Carvão Vegetal/química , Poluentes Químicos da Água/química , Adsorção , Bacillus , Biomassa , Cádmio/análise , Cinética , Metais Pesados , Minerais/química , Solo , Água , Poluentes Químicos da Água/análise
19.
Environ Sci Pollut Res Int ; 26(23): 24143-24161, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31228066

RESUMO

This batch and column kinetics study of arsenic removal utilized copper-impregnated natural mineral tufa (T-Cu(A-C)) under three ranges of particle size. Non-competitive kinetic data fitted by the Weber-Morris model and the single resistance mass transfer model, i.e., mass transfer coefficient kfa and diffusion coefficient (Deff) determination, defined intra-particle diffusion as the dominating rate controlling step. Kinetic activation parameters, derived from pseudo-second-order rate constants, showed low dependence on adsorbent geometry/morphology and porosity, while the diffusivity of the pores was significant to removal efficacy. The results of competitive arsenic adsorption in a multi-component system of phosphate, chromate, or silicate showed effective arsenic removal using T-Cu adsorbents. The high adsorption rate-pseudo-second-order constants in the range 0.509-0.789 g mg-1 min-1 for As(V) and 0.304-0.532 g mg1 min1 for As(III)-justified further application T-Cu(A-C) in a flow system. The fixed-bed column adsorption data was fitted using empirical Bohart-Adams, Yoon-Nelson, Thomas, and dose-response models to indicate capacities and breakthrough time dependence on arsenic influent concentration and the flow rate. Pore surface diffusion modeling (PSDM), following bed-column testing, further determined adsorbent capacities and mass transport under applied hydraulic loading rates.


Assuntos
Arsênico/isolamento & purificação , Cobre/química , Minerais/química , Purificação da Água/métodos , Adsorção , Arsênico/química , Cromatos/química , Difusão , Cinética , Fosfatos/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/instrumentação
20.
Chemistry ; 25(55): 12740-12750, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31241793

RESUMO

The biological mediation of mineral formation (biomineralization) is realized through diverse organic macromolecules that guide this process in a spatial and temporal manner. Although the role of these molecules in biomineralization is being gradually revealed, the molecular basis of their regulatory function is still poorly understood. In this study, the incorporation and distribution of the model intrinsically disordered starmaker-like (Stm-l) protein, which is active in fish otoliths biomineralization, within calcium carbonate crystals, is revealed. Stm-l promotes crystal nucleation and anisotropic tailoring of crystal morphology. Intracrystalline incorporation of Stm-l protein unexpectedly results in shrinkage (and not expansion, as commonly described in biomineral and bioinspired crystals) of the crystal lattice volume, which is described herein, for the first time, for bioinspired mineralization. A ring pattern was observed in crystals grown for 48 h; this was composed of a protein-enriched region flanked by protein-depleted regions. It can be explained as a result of the Ostwald-like ripening process and intrinsic properties of Stm-l, and bears some analogy to the daily growth layers of the otolith.


Assuntos
Carbonato de Cálcio/química , Minerais/química , Membrana dos Otólitos/metabolismo , Proteínas Recombinantes/química , Animais , Peixes , Membrana dos Otólitos/química , Proteínas Recombinantes/metabolismo
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