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1.
Nature ; 583(7814): 66-71, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32612224

RESUMO

Dental enamel is a principal component of teeth1, and has evolved to bear large chewing forces, resist mechanical fatigue and withstand wear over decades2. Functional impairment and loss of dental enamel, caused by developmental defects or tooth decay (caries), affect health and quality of life, with associated costs to society3. Although the past decade has seen progress in our understanding of enamel formation (amelogenesis) and the functional properties of mature enamel, attempts to repair lesions in this material or to synthesize it in vitro have had limited success4-6. This is partly due to the highly hierarchical structure of enamel and additional complexities arising from chemical gradients7-9. Here we show, using atomic-scale quantitative imaging and correlative spectroscopies, that the nanoscale crystallites of hydroxylapatite (Ca5(PO4)3(OH)), which are the fundamental building blocks of enamel, comprise two nanometric layers enriched in magnesium flanking a core rich in sodium, fluoride and carbonate ions; this sandwich core is surrounded by a shell with lower concentration of substitutional defects. A mechanical model based on density functional theory calculations and X-ray diffraction data predicts that residual stresses arise because of the chemical gradients, in agreement with preferential dissolution of the crystallite core in acidic media. Furthermore, stresses may affect the mechanical resilience of enamel. The two additional layers of hierarchy suggest a possible new model for biological control over crystal growth during amelogenesis, and hint at implications for the preservation of biomarkers during tooth development.


Assuntos
Amelogênese , Esmalte Dentário/química , Ácidos/química , Cálcio/química , Carbonatos/química , Cristalização , Teoria da Densidade Funcional , Esmalte Dentário/ultraestrutura , Durapatita/química , Fluoretos/química , Humanos , Magnésio/química , Microscopia Eletrônica de Transmissão e Varredura , Sódio/química , Tomografia , Difração de Raios X
2.
Chemosphere ; 257: 127140, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32526467

RESUMO

The recent increase in municipal sludge worldwide has led to a great deal of interest in developing an efficient and environmentally friendly sludge treatment method. In the paper, the treatment of municipal sludge by hydrothermal oxidation (HTO) process with H2O2 as the oxidant was proposed. The impacts of HTO temperature and H2O2 mass fraction on the distribution of products, the moisture content, the migration behaviors of the heavy metals (HMs) of the resulted solid products, the concentration of volatile fatty acids (VFAs) and NH3-N contained in the resulted aqueous phase products and the pH value were investigated. The results indicated that the sludge reduction was achieved by HTO treatment, the increasing H2O2 mass fraction and HTO temperature can significantly improve the dewatering performance of the sludge. The potential toxicity fraction of Pb and Cd contained in the resulted solid residual increased with the increasing HTO severity and the potential toxicity fraction of solid residues was still lower than that of raw material. Acetic acid was the main VFAs produced from HTO treated sludge, and its concentration reached to the maximum value of 2923.41 mg/L at 230 °C under H2O2 mass fraction of 15%. The change in the pH of the resulted aqueous phase products was caused by the competition between the acidic (VFAs or CO2) or alkaline (NH3-N) substances derived from the sludge during HTO process. The HTO process was expected to be an efficient method for municipal sludge treatment due to its mild conditions and high heavy metal safety.


Assuntos
Eliminação de Resíduos Líquidos , Ácidos , Peróxido de Hidrogênio , Governo Local , Metais Pesados/química , Oxidantes , Oxirredução , Esgotos/química , Temperatura
3.
Bioresour Technol ; 313: 123604, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32540693

RESUMO

Metabolic potential of two different cultures, facultative (FB) and strict anaerobes (AB) under two microenvironments [anoxic (ANOX) and anaerobic (ANA)] was evaluated to understand acidogenic fermentation in a self-induced electrofermentation (EF) system for the production of short-chain fatty acids (SCFA: C2-C4) and biogas. ANA condition positively influenced FB and AB metabolism towards higher acetic (C2:2390 mg/L) and propionic acid (C3: 717 mg/L) production, while butyric acid (C4:1481 mg/L) favored ANOX microenvironment (AB). ANOX microenvironment showed a better self-induced potential compared to ANA metabolism (0.46 V (FBANOX); 0.45 V (ABANOX)). An improved H2 (>30%) fraction was noticed with FB while CH4 production was found favourable with AB. The study illustrated the role of system microenvironment in association with metabolic function towards regulating electrofermentation towards specific products synthesis.


Assuntos
Biocombustíveis , Ácidos Graxos Voláteis , Ácidos , Fermentação , Concentração de Íons de Hidrogênio
4.
Chemosphere ; 256: 127045, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32454350

RESUMO

Four different metal-contaminated calcareous soil types, Carbonati-Perudic Cambosols (CPC), Fe-accumuli-Stagnic Anthrosols (FSA), Ochri-Aquic Cambosols (OAC) and Calci-Orthic Aridosols (COA), were investigated. The acid buffering capacity and metal-releasing behaviors of the soils were explored using an acid extraction method. Soil incubation and pot experiments were conducted to investigate changes in soil metal speciation and the enhancement of phytoextraction by soil acidification. There were several to tens of times differences in acid buffering capacities between soils. Soil calcium content may represent the major buffering system as indicated by significant linear correlations between the amount of Ca2+ released and H+ addition, and metal release into solution with H+ addition showed three stages, i.e. little release, slow release and rapid release stages. Soil carbonate-bound and Fe/Mn oxide-bound Cd and Zn decreased with the addition of H+ to all four soils, but organic matter-bound and residual metals remained unchanged. Based on the intensity of acidification, the efficiency Cd and Zn phytoextraction increased substantially with the addition of H+ in the case of the CPC but not the FSA which had a higher acid buffering capacity than the CPC. Hence, it may be concluded that the acid buffering capacity and changes in soil metal fractions with acidification of contaminated calcareous soil types should be determined before phytoextraction of these soils is attempted.


Assuntos
Biodegradação Ambiental , Metais Pesados/análise , Poluentes do Solo/análise , Ácidos , Cádmio , Metais , Solo
5.
Chemosphere ; 252: 126570, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32443266

RESUMO

Hydrotalcite precipitation is a promising technology for the on-site treatment of acid mine drainage (AMD). This technology is underpinned by the synthesis of hydrotalcite that can effectively remove various contaminants. However, hydrotalcite precipitation has only limited capacity to facilitate sulfate removal from AMD. Therefore, the feasibility of coupling biological sulfate reduction with the hydrotalcite precipitation to maximize sulfate removal was evaluated in this study. AMD emanating from a gold mine (pH 4.3, sulfate 2000 mg L-1, with various metals including Al, Cd, Co, Cu, Fe, Mn, Ni, Zn) was first treated using the hydrotalcite precipitation. Subsequently, biological treatment of the post-hydrotalcite precipitation effluent was conducted in an ethanol-fed fluidized bed reactor (FBR) at a hydraulic retention time (HRT) of 0.8-1.6 day. The hydrotalcite precipitation readily neutralized the acidity of AMD and removed 10% of sulfate and over 99% of Al, Cd, Co, Cu, Fe, Mn, Ni, Zn. The overall sulfate removal increased to 73% with subsequent FBR treatment. Based on 454 pyrosequencing of 16S rRNA genes, the identified genera of sulfate-reducing bacteria (SRB) included Desulfovibrio, Desulfomicrobium and Desulfococcus. This study showed that sulfate-rich AMD can be effectively treated by integrating hydrotalcite precipitation and a biological sulfate reducing FBR.


Assuntos
Hidróxido de Alumínio/química , Hidróxido de Magnésio/química , Eliminação de Resíduos/métodos , Sulfatos/química , Ácidos , Reatores Biológicos/microbiologia , Concentração de Íons de Hidrogênio , Metais , Mineração , Oxirredução , RNA Ribossômico 16S
6.
Sci Total Environ ; 731: 138751, 2020 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-32413650

RESUMO

The conventional studies on the preparation of nanocellulose used a high concentration of sulfuric acid that is difficult to remove and recover. A biochar-based solid acid with magnetic properties was developed to hydrolyze cellulose to prepare nanocellulose in this work. Two different methods were selected to investigate the properties of the synthesized magnetic carbon-based solid acids. The synthesized catalysts were characterized by SEM, TEM, XRD, NH3-TPD and FT-IR. The experimental results showed that two solid acids by the microwave-assisted synthesis had good magnetic properties by a magnet adsorption. Analysis by SEM and TEM showed that the two solid acids had rich pore structures. According to mineral element analysis, both solid acids contained high sulfur content. The solid acid was an amorphous carbon structural material with a surface rich in active groups. The catalytic activity of the biochar-based solid acids in cellulose hydrolysis to prepare nano-scale cellulosic material was evaluated. It was found that magnetic biochar-based solid acid (MBC-SA1) could achieve a high yield, which produced up to 57.68% for hydrolyzing cellulose into nanometers.


Assuntos
Celulose , Micro-Ondas , Ácidos , Hidrólise , Espectroscopia de Infravermelho com Transformada de Fourier
7.
Chemosphere ; 251: 126561, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32443240

RESUMO

In this study, low-temperature catalytic NO oxidation with H2O2 over Na- and H-exchanged Y and ZSM-5 zeolites was investigated at 140 °C which is the average exhaust temperature of coal-fired power plant. Fast catalytic NO oxidation rates were observed over H-zeolites, and catalytic activity was proportional to the amount of Brønsted acid sites. HZSM-5 and HY zeolites show 65% and 95% NO removal efficiency, respectively, but the catalytic stability of HY was lower than HZM-5 due to partial dealumination during the reaction. In-situ DRIFTS analysis showed that NO+ species coordinated at framework sites played a direct role in the catalytic NO oxidation. Moreover, the possible reaction pathway was proposed to elucidate the mechanism of NO oxidation with H2O2 catalyzed over Brønsted acid sites. The effect of reaction temperature, H2O2 concentration, H2O2 flow and SO2 concentration on NO oxidation were investigated over H-zeolites. The experimental results indicated that the NO removal efficiency was increased with the increase of H2O2 concentration, but decreased with the increase of SO2 concentration. The NO removal efficiency first increased and then decreased with the increase of H2O2 flow and reaction temperature.


Assuntos
Poluentes Atmosféricos/análise , Peróxido de Hidrogênio/química , Óxidos de Nitrogênio/análise , Zeolitas/química , Ácidos/química , Poluentes Atmosféricos/química , Catálise , Temperatura Baixa , Modelos Teóricos , Óxidos de Nitrogênio/química , Oxirredução , Centrais Elétricas
8.
Int J Syst Evol Microbiol ; 70(5): 3348-3354, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32375942

RESUMO

A novel acidophilic member of the phylum Actinobacteria was isolated from an acidic, metal-contaminated stream draining from an abandoned underground coal mine (Trongol mine), situated close to Curanilahue, Biobío Region, Chile. The isolate (USS-CCA1T) was demonstrated to be a heterotroph that catalysed under aerobic conditions the oxidation of ferrous iron and the reduction of ferric iron under anaerobic conditions, but not the oxidation of sulfur nor hydrogen. USS-CCA1T is a Gram-positive, motile, short rod-shaped, mesophilic bacterium with a temperature growth optimum at 30 °C (range 20-39 °C). It was categorized as an extreme acidophile growing between 1.7 and 4.5 and optimally at pH 3.0. The G+C content of the chromosomal DNA of the isolate was 74.1 mol%, which is highly related to Aciditerrimonas ferrireducens IC-180T , (the most closely related genus; 94.4 % 16S rRNA gene identity), and higher than other acidophilic actinobacteria. The isolate (USS-CCA1T) was shown to form a distinct 16S rRNA clade from characterized acidophilic actinobacteria, well separated from the genera Acidimicrobium, Ferrimicrobium, Ferrithrix, 'Acidithrix' and Aciditerrimonas. Genomic indexes (ANIb, DDH, AAI, POCP) derived from the USS-CCA1T draft genome sequence (deposited at DDBJ/ENA/GenBank under the accession WJHE00000000) support assignment of the isolate to a new species and a new genus within the Acidimicrobiaceae family. Isolate USS-CCA1T is the designated type strain of the novel species Acidiferrimicrobium australe (=DSM 106828T,=RGM 2506T).


Assuntos
Actinobacteria/classificação , Processos Heterotróficos , Ferro/metabolismo , Mineração , Filogenia , Microbiologia da Água , Ácidos , Actinobacteria/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , Chile , DNA Bacteriano/genética , Ácidos Graxos/química , Concentração de Íons de Hidrogênio , Oxirredução , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
9.
Chemosphere ; 253: 126742, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32464754

RESUMO

This work deals with the distribution of rare earth elements (REE) in the abandoned Tharsis mines under different hydrological conditions. High concentrations of REE were observed; mean value of 1747 µg/L. The highest concentrations of REE were recorded during the dry period (DP, mean of 2220 µg/L) due to high evaporation and strong water-rock interactions. However, some sampling points showed the highest REE concentrations during the wet period (WP) due to the washing out of large dumps during intense rainfall. The concentration of REE shows a positive correlation with electrical conductivity (EC) and a negative correlation with pH because more acidic conditions enhance dissolution of minerals. However, the highest concentrations of REE occurred in samples with intermediate levels of metal pollution and EC values. The highest correlations of middle REE (MREE) and heavy REE (HREE) occurred with elements related to hydrothermal mineralisation of Mn and Ni, associated with sulphide deposits. The normalised patterns of the AMD sources showed an enrichment of MREE over light REE (LREE) and HREE in all samples. The use of REE patterns as geochemical tracers confirmed the conservative behaviour of REE in the fluvial network, that is, they are not affected by the precipitation of mineral phases. The quantification of REE released from AMD sources to water bodies reveals that, although the highest concentrations occur during the DP, the main load of REE occurs during the WP, due to the highest discharges, with 6.62 kg/day of LREE, 1.12 kg/day of MREE, and 0.54 kg/day of HREE.


Assuntos
Metais Terras Raras/análise , Mineração , Poluentes Químicos da Água/análise , Ácidos , Monitoramento Ambiental , Minerais , Estações do Ano , Espanha , Sulfetos
10.
Bioresour Technol ; 311: 123517, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32413643

RESUMO

To overcome the recalcitrance of residual lignins in acid-pretreated larch (AL), a combined acid and alkali pretreatment with in-situ lignin modification was developed in this study. The results showed that introducing in-situ lignin modification with 2-naphthol to acid pretreatment (160 and 180 oC) improved the enzymatic digestibility of AL by 12.7-14.4%, through suppressing lignin repolymerization. The obviously higher improvement (57.8-88.3%) was achieved by applying alkali post-treatment (90 oC) with poly (ethylene glycol) diglycidyl ether (PEGDE) on AL, mainly due to the function of in-situ lignin modification with PEGDE for reducing enzyme non-productive binding on lignins. More importantly, the synergism of 2-naphthol and PEGDE modification facilitated the enzymatic hydrolysis of AL more significantly. Its beneficial mechanism was explored by investigating the effects of in-situ lignin modification on lignin properties, including extraction yields, functional groups, and enzyme affinity of lignins. Results will give insights into establishing an efficient pretreatment of softwood biomass.


Assuntos
Larix , Lignina , Ácidos , Álcalis , Hidrólise
11.
Bioresour Technol ; 311: 123474, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32447227

RESUMO

In this study, chemoenzymatic conversion of Sorghum durra stalk (SDS) into furoic acid was developed by a sequential microwave-assisted solid acid conversion and immobilized whole-cells biocatalysis method. Dry dewaxed SDS (75 g/L) was catalyzed into furfural at 57.8% yield with heterogeneous Sn-argil (2.0 wt% dosage) in n-ethyl butyrate-H2O (1:1, v:v) biphasic system using a microwave (600 W) for 10 min at 180 °C. In this biphasic media (pH 6.5), SDS-derived furfural (125.0 mM) was biologically oxidized to furoic acid by immobilized Brevibacterium lutescens cells harboring furfural-oxidizing activity at 30 °C, and furfural was wholly transformed to furoic acid within 24 h. Finally, the recovery and reuse of the Sn-argil catalyst and immobilized biocatalysts were conducted for synthesizing furoic acid from SDS in the biphasic system. This chemoenzymatic route can be attractive for furoic acid production.


Assuntos
Sorghum , Ácidos , Biocatálise , Furaldeído , Micro-Ondas
12.
Sci Total Environ ; 729: 139005, 2020 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-32361456

RESUMO

Phenomics is originally a biological concept. In the most recent years, the studies of plant and human phenomics have started, and show a strong momentum and trend of development. In this paper, based on the related research on bioleaching/acid mine drainage (AMD), we put forward the relevant concepts and methodology of phenomics of microbe-mineral interaction (MMI) in bioleaching/AMD environments. It refers to the systematic study on phenotypes of MMI on both levels of microbiome and mineralome under various environmental conditions, by which it gives the relationship between microbial/mineral genome and phenome of MMI responding to the varying environmental conditions. The pertinent methodology is of mainly (meta)-omics, synchrotron radiation-based techniques and supercomputing-based density function theory (DFT) calculation.


Assuntos
Mineração , Fenômica , Ácidos , Humanos , Minerais
13.
Chemosphere ; 254: 126861, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32348925

RESUMO

The remediation of cadmium-pyrene co-contaminated soil by electrokinetic (EK) and the influence factors were investigated in this study. The artificial contaminated soils were treated for 20 days in EK experimental setups without electrolyte solution reservoirs, to simulate in-situ remediation of unsaturated soil. The results indicated that polarity-reversing electric field had maintained soil pH in the range of 7.27-7.67. Cadmium (Cd) contaminant would aggregate near electrodes, and the average Cd concentration in these areas had reached 72.21 mg/kg (original 51.6 mg/kg), while the value in soil farthest away from electrodes was 33.58 mg/kg. The reasons for Cd aggregated were: the insoluble hydroxide formations attribute to the frequently alternation of acid-base environment, and the decrease of pH and water holding capacity in soil away from electrodes would promote the dissolved Cd movement by electro-osmosis flow. Although the applied electric field could promote the growth and activity of pyrene-degrading microorganisms (PDM), the soluble Cd would be the restriction factor, especially in soil near electrodes. However, the highest (56.38%) pyrene removal efficiency (PRE) was achieved near electrodes due to the synergistic effect of electric filed and PDM, and PRE was positively correlated with the PDM number in soil away from electrodes.


Assuntos
Cádmio/análise , Recuperação e Remediação Ambiental , Poluentes do Solo/análise , Ácidos , Eletricidade , Eletrodos , Poluição Ambiental , Concentração de Íons de Hidrogênio , Pirenos , Solo/química
14.
Mar Pollut Bull ; 155: 111147, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32310103

RESUMO

The surface sediments from the Bohai Sea (BS) and the northern Yellow Sea (NYS) were analyzed for acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) to assess the sediment quality. The results indicated that >60% of the samples were found to have possible adverse effects on aquatic life in the BS based on the difference between the concentrations of AVS ([AVS]) and SEM ([SEM]), and the corresponding percentage in the NYS was <25%. Nevertheless, there was no indication of adverse effects for all the BS and the NYS samples when the total organic carbon (TOC) concentration was introduced in the sediment quality evaluation with [AVS] and [SEM]. The grain size composition, TOC, water content and pH all had significant influence on the distribution of [SEM] and the [SEM]/[AVS] ratios; while, in contrast, the distribution of [AVS] could be mainly determined by the redox condition of sediment.


Assuntos
Metais Pesados/análise , Poluentes Químicos da Água/análise , Ácidos , Monitoramento Ambiental , Sedimentos Geológicos , Metais/análise , Sulfetos/análise
15.
Nat Commun ; 11(1): 1817, 2020 04 14.
Artigo em Inglês | MEDLINE | ID: mdl-32286311

RESUMO

Dendritic cells (DCs) constitute a specialized population of immune cells that present exogenous antigen (Ag) on major histocompatibility complex (MHC) class I molecules to initiate CD8 + T cell responses against pathogens and tumours. Although cross-presentation depends critically on the trafficking of Ag-containing intracellular vesicular compartments, the molecular machinery that regulates vesicular transport is incompletely understood. Here, we demonstrate that mice lacking Kif5b (the heavy chain of kinesin-1) in their DCs exhibit a major impairment in cross-presentation and thus a poor in vivo anti-tumour response. We find that kinesin-1 critically regulates antigen cross-presentation in DCs, by controlling Ag degradation, the endosomal pH, and MHC-I recycling. Mechanistically, kinesin-1 appears to regulate early endosome maturation by allowing the scission of endosomal tubulations. Our results highlight kinesin-1's role as a molecular checkpoint that modulates the balance between antigen degradation and cross-presentation.


Assuntos
Apresentação do Antígeno/imunologia , Células Dendríticas/metabolismo , Endossomos/metabolismo , Cinesina/metabolismo , Ácidos/metabolismo , Animais , Antígenos/metabolismo , Antígenos CD/metabolismo , Células da Medula Óssea/citologia , Proliferação de Células , Endocitose , Antígenos de Histocompatibilidade Classe I/metabolismo , Cinesina/deficiência , Camundongos Knockout , Camundongos Transgênicos , Microtúbulos/metabolismo , Neoplasias/patologia , Ovalbumina/imunologia , Solubilidade
16.
J Chromatogr A ; 1621: 461066, 2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32299623

RESUMO

The ion-exchange and complex forming equilibria were quantitatively described and demonstrated in order to understand major factors in the control of selectivity in the analytical separation of carboxylic acids and inorganic anions in cryptand based ion chromatography. A complex retention model has been developed for the separation on a non-conventional IC column. Changes in retention are treated both theoretically and experimentally. Retention mechanism is employed on a macrocycle-based (cryptand n-decyl-[2.2.2]) ion-exchange chromatographic phase to improve the selectivity for a mixture of model analytes. We introduced an alternative internal gradient method by mixed eluent (i.e. eluents formed by combination of two alkali hydroxide with different molar ratio). The effect of binary mixed eluent (Li/Na, Li/K) on the retention behavior and peak shape of carboxylic acids are also discussed in view of the proposed theory. It was shown that the effects of binary aqueous mobile phases, held isocratically behave very similar to the step gradient mode. The "internal gradient" separation system has advantages over traditional step gradient mode. Twenty-six anions of widely varying chemical character (mono-, di-, tri-valent inorganic anions, mono-, di-, tri-valent aliphatic carboxylic acids, aromatic- and haloacetic carboxylic acids) were investigated on the cryptand-based (D222) stationary phase using different methods by LiOH, NaOH and KOH eluent. The predicted vs measured retention data are in rather good agreement. High degree of linearity was obtained for inorganic anions, multivalent carboxylic acids, and for aromatic and haloacetic acids R2 = 0.992, 0.969, and 0.980, respectively.


Assuntos
Ácidos Carboxílicos/análise , Cromatografia por Troca Iônica/métodos , Éteres Cíclicos/química , Bases de Schiff/química , Ácidos/química , Ânions/química , Ácidos Carboxílicos/isolamento & purificação , Troca Iônica
17.
Sci Total Environ ; 718: 137394, 2020 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-32325624

RESUMO

Sulfate-reducing biofilters operated in semi-passive or passive modes constitute an approach of choice for treatment of acidic mining effluents. The aim of the present study involved examining the behavior of biofilters after use based on two modes of management, namely in unsaturated and saturated media. Two acidophilic biofilters were investigated following their mixing with different alkaline industrial residues (i.e., 25% fly ash biomass or 30% aluminum red mud, or 10% kiln dust). Percolation column tests for a 330-d period indicated that aluminum red mud and lime kiln dust (to a lesser extent) are efficient materials for maintaining the pH neutrality of biofilter leachate and to reduce release of metals (i.e., Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) in spent biofilters. The storage of biofilters in saturated mode also makes it possible to preserve the reducing conditions of the environment and neutrality of the pH and to limit the dissolution of the solution of cadmium, nickel and zinc. Conversely, increased iron release is noted under saturated conditions. Finally, the results indicated that a mixture of biofilters and lime kiln dust is preferable to surface addition of these to reduce the loss of metals in leachates.


Assuntos
Mineração , Ácidos , Concentração de Íons de Hidrogênio , Metais , Sulfatos
18.
PLoS One ; 15(4): e0231589, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32320411

RESUMO

The Arctic Ocean is an early warning system for indicators and effects of climate change. We use a novel combination of experimental and time-series data on effects of ocean warming and acidification on the commercially important Northeast Arctic cod (Gadus morhua) to incorporate these physiological processes into the recruitment model of the fish population. By running an ecological-economic optimization model, we investigate how the interaction of ocean warming, acidification and fishing pressure affects the sustainability of the fishery in terms of ecological, economic, social and consumer-related indicators, ranging from present day conditions up to future climate change scenarios. We find that near-term climate change will benefit the fishery, but under likely future warming and acidification this large fishery is at risk of collapse by the end of the century, even with the best adaptation effort in terms of reduced fishing pressure.


Assuntos
Biomassa , Mudança Climática , Pesqueiros/tendências , Gadus morhua/fisiologia , Água do Mar/química , Ácidos/análise , Animais , Pesqueiros/economia , Pesqueiros/estatística & dados numéricos , Modelos Estatísticos
19.
Artigo em Inglês | MEDLINE | ID: mdl-32248046

RESUMO

The present study is the first report of in-situ growth and application of nanorods-flower like Co3O4 nanosorbent coated on the anodized aluminum substrate for thin film microextraction (TFME) approach. The flower like Co3O4 was successfully fabricated by conversion of Co-Al layered double hydroxide (LDH) precursor to Co3O4 using the simple calcinations process. The cheap and available aluminum foil was electrochemically anodized and used as a porous substrate. Response surface methodology (RSM) was explored for optimization step. Different acidic drugs, including: paracetamol, ibuprofen, aspirin and diclofenac were extracted from biological fluids in order to investigate the capability of the prepared sorbent. The extracted analytes were then analyzed using high performance liquid chromatography-ultraviolet detection (HPLC-UV). Under the optimized conditions, the limits of detection were between 0.2 and 1.7 µg L-1 in different selected matrices. The obtained limits of quantification were also calculated to be between 0.8 and 5.1 µg L-1 in the selected matrices. In addition the enrichment factors were also in the range of 105-169. Batch-to-batch reproducibility at 100 µg L-1 concentration level was also evaluated to be lower than 5.2% (n = 3). Finally, the method was successfully used for analysis of these compounds in the biological fluids.


Assuntos
Ácidos/urina , Alumínio/química , Cobalto/química , Nanotubos/química , Óxidos/química , Acetaminofen/urina , Adsorção , Adulto , Aspirina/urina , Cromatografia Líquida de Alta Pressão , Diclofenaco/urina , Técnicas Eletroquímicas , Eletrodos , Feminino , Humanos , Hidróxidos/química , Ibuprofeno/urina , Limite de Detecção , Masculino , Reprodutibilidade dos Testes , Microextração em Fase Sólida , Propriedades de Superfície
20.
Chemosphere ; 253: 126665, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32278191

RESUMO

Acid mine drainage (AMD) represents a major problem in the mining industry worldwide due to the risk of water and soil pollution. Its active treatment involves the addition of alkaline reagents such as NaOH or Ca(OH)2 to increase the pH and precipitate the dissolved metals, although substantial amounts of dissolved ions might persists. Under a remediation approach, the aim of this work was to assess the chemical and physical characteristics of treated effluent and to evaluate its ecotoxicological effects on zebrafish (Danio rerio) embryonic and larval stages, through developmental, functional, morphological, and behavioral end-points. The studied AMD sample, highly associated with pyrite, presented high sulfate and dissolved metal ions content and was submitted to the following treatment conditions: NaOH - pH 7.0 and 8.7, and Ca(OH)2 - pH 7.0 and 8.7. All neutralizing treatments resulted in a satisfactory reduction of the metals concentration, with best results achieved using Ca(OH)2 at pH 8.7; although Mn and As still remained above or very near the discharge maximum limits according to Brazilian legislation. Therefore, an additional step was employed to Mn and As adsorption by algal biomass. Regarding in-vivo toxicological assays, no significant lethality was recorded in all treated AMD groups, although adverse effects were observed in all endpoints analyzed. Ca(OH)2 groups performed closer to control than NaOH-treated groups. The additional polishing stage treatment with the algae Scenesmus sp. allowed tenuous improvements in terms of removal of residual amounts of As and Mn but not in the toxicological characteristics of treated AMD.


Assuntos
Mineração , Poluentes Químicos da Água/química , Ácidos/química , Adsorção , Animais , Brasil , Ecotoxicologia , Concentração de Íons de Hidrogênio , Ferro , Metais/análise , Sulfatos , Sulfetos , Água , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Peixe-Zebra/fisiologia
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