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1.
Environ Monit Assess ; 192(2): 103, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31915995

RESUMO

Solar ultraviolet (UV) radiation exhibits a significant degradation for dissolved organic matter (DOM) in natural water ecosystems. However, research on photodegradation process of terrestrial components (e.g., humic-like substances) of DOM are limited due to drastic water dilution and rapid degradation. Here, photochemical degradation of terrestrial soil DOM with abundant humic-like substances from different land use were investigated by utilizing spectral technologies. Simulated UV radiation caused obvious losses on concentration, component structures, and fluorescence characteristic of soil DOM samples. The correlations between absorption specific parameters (a280, SUVA254, and SR) and dissolved organic carbon (DOC) were especially pronounced (p < 0.05), which could be used as valid indicators to determine changes in DOM composition and molecular size during photobleaching process. The decreases of DOM fluorescence intensity were corresponded to first-order kinetic and half-life reactions. The greatest reduction on fluorescence intensity (31.56-81.97%) belonged to peak C (i.e., humic-like substances). Overall, DOM from forest and grass soil ecosystems was more easily photochemical degraded than anthropogenic soil DOM. Enhancive contribution of fresh DOM formed by photodegradation increased autochthonous characteristic and bioavailable nutrition by increasing biological index (BIX) values and ammonia nitrogen (NH4+-N) concentration. The slight microbial decomposition effects on DOM happened in unsterilized dark condition. Our findings provided insights for understanding the rapid photodegradation processes of composition and structure of terrestrial DOM. Graphical abstract.


Assuntos
Substâncias Húmicas/efeitos da radiação , Compostos Orgânicos/efeitos da radiação , Solo/química , Raios Ultravioleta , Ecossistema , Monitoramento Ambiental , Fluorescência , Substâncias Húmicas/análise , Compostos Orgânicos/química , Fotólise
2.
Chemosphere ; 242: 125251, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31896185

RESUMO

A novel nano-composite material (CMC-FeS@HA) combining the advantages of humic acid (HA) and FeS was synthesized to remediate hexavalent chromium (Cr(VI)) contaminated soil along with chromium (Cr) resistant microflora. The characteristic analysis confirmed the successful synthesis of the nano-composite, which provided further mechanism evidence of its detoxification effect on polluted soil. Energy Dispersive System analysis proved the adsorption of the microbe consortium (MC) for Cr. After remediation, Cr(VI) in all treatments was dramatically reduced and the leachable Cr in soil treated by CMC-FeS@HA and MC decreased 89.14% compared with control. The result of BCR sequential extraction showed that Cr was stabilized, whose form changed to oxidizable and residual from HOAC-extractable. Besides, CMC-FeS@HA, as a sustained-release acid with high biocompatibility, could continuously decrease the pH of strongly alkaline soil and created a suitable micro-ecological environment for soil microorganisms. Moreover, CMC-FeS@HA dramatically improved soil physicochemical property, soil microbial activity (dehydrogenase, hydrolase, urease, and invertase activities), and soil microecological diversity. In total, this study provided a useful technology for soil remediation, which innovatively combined chemical remediation and microbial-remediation with a positive effect on soil quality, providing a good approach for the multiple technology combination in the environmental cause.


Assuntos
Cromo/análise , Recuperação e Remediação Ambiental/métodos , Poluentes do Solo/análise , Adsorção , Poluição Ambiental/análise , Substâncias Húmicas/análise , Oxirredução , Solo/química
3.
Chemosphere ; 242: 125227, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31704522

RESUMO

It is crucial to explore the source, formation process and interdependence of disinfection byproducts (DBPs) to reduce their risk on public health. In this investigation, a source water was chlorinated to evaluate the initial formation rates and the maximum yields of trichloromethane (TCM), dichloroacetic acid (DCAA), and trichloroacetic acid (TCAA) based on a hyperbola model. The results showed that TCM achieved the highest initial formation rate and maximum theoretical concentration compared with DCAA and TCAA. The TCM yield can be used to forecast the yields of DCAA and TCAA throughout the whole reaction process, and the yields of chloral hydrate (CH), dichloroacetonitrile (DCAN) and 1,1,1-trichloropropanone (1,1,1-TCP) within the initial reaction stage. Besides, the raw water, settled water and filtered water collected from a drinking water treatment plant were divided into five fractions, respectively, by ultrafiltration membranes to evaluate their DBP formation after chlorination. Compared with the medium molecular weight species, high and low molecular weight organic matters exhibited relatively high specific regulated and unregulated DBP yields (expressed as µg/mg C), respectively. Humic acid-like compositions predominantly contributed to regulated DBP yields, while soluble microbial by-product-like compounds preferentially generated DCAN. The correlation study revealed that the TCM could also serve as an indicator for the measured DBPs from chlorination of sample fractions with different molecular weight. Finally, it was found that the theoretical cytotoxicity was enhanced during chlorination of filtered water compared with chlorination of settled water.


Assuntos
Desinfetantes/química , Desinfecção/métodos , Água Potável/química , Halogenação , Purificação da Água/métodos , Acetonitrilos/análise , Clorofórmio/análise , Ácido Dicloroacético/análise , Desinfetantes/análise , Água Potável/análise , Substâncias Húmicas/análise , Ácido Tricloroacético/análise , Ultrafiltração/efeitos adversos , Poluentes Químicos da Água/análise
4.
Chemosphere ; 242: 125256, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31704524

RESUMO

Ultraviolet-quenching substances (UVQS), recently identified pollutants in landfill leachate, can interfere with ultraviolet disinfection when landfill leachate is co-treated with municipal sewage. This study investigated the elimination of UVQS in mature landfill leachates through a membrane bioreactor (MBR) and a semi-aerobic aged refuse biofilter (SAARB). Humus (i.e., fulvic and humic acids) was the main component of organic matter in both MBR- and SAARB-treated landfill leachates, while there was a more stable chemical structure of humus in the MBR-treated leachate. The concentration of UVQS in MBR-treated mature landfill leachate was higher than that of SAARB-treated leachate. Ozonation can degrade UVQS effectively, especially for landfill leachate containing a high concentration UVQS (i.e., MBR-treated landfill leachate). However, a large accumulation of small molecule acid might be caused by ozonation for highly concentrated UVQS in landfill leachate, leading to the delayed degradation of total organic carbon. Moreover, ozonation degraded both fulvic acid and humic acid; and degraded humic acid more effectively. For instance, 88.0% removal (MBR-CP2) and 96.0% removal (SAARB-CP2) of humic acid was higher than those (83.3% for MBR-CP1 and 92.3% for SAARB-CP1) of fulvic acid. The destruction of UV-quenching functional groups of organics (such as CC) by ozone was the main UVQS degradation mechanism of ozonation applied to MBR- and SAARB-treated landfill leachates. Therefore, the ozonation process can efficiently decrease UV absorption intensity in both MBR- and SAARB-treated landfill leachates.


Assuntos
Reatores Biológicos , Filtração , Ozônio/química , Poluentes Químicos da Água/química , Benzopiranos/química , Resíduos de Alimentos , Substâncias Húmicas/análise , Eliminação de Resíduos , Esgotos , Raios Ultravioleta , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/efeitos da radiação
5.
Chemosphere ; 242: 125062, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31704527

RESUMO

Removing dissolved organic matter (DOM) is of great concern due to its adverse effects on water supplies. Great effort has been given to studying DOM removal by coagulation, while the mechanism of DOM removal and the changes in its properties during coagulation have not been clearly illustrated due to the limitations of detection methods under practical environmental conditions. In this paper, the changes in DOM during coagulation were quantified using differential UV-Visible absorbance spectroscopy, and the differential spectra of DOM in the wavelength range of 200-600 nm could be deconvoluted into six Gaussian bands with maxima at approximately 200, 240, 276, 316, 385, and 457 nm after coagulation, respectively. The intensity of these maxima decreased with the type and dosage of coagulants. These observations should reflect the difference in the removability of DOM by coagulation, and this perspective was further confirmed by examining the deprotonation-protonation properties of DOM before and after coagulation. The affinity sites of DOM in coagulated waters, quantified by spectra parameter DlnA400 (differential log-transformed spectra at wavelength 400 nm) in combination with the revised NICA model, increased as the coagulant dosage, which indicates that coagulation is inclined to remove the DOM fraction with fewer functional groups. Polyaluminum chloride (PAC) and Al-aggregate (Al13) were more efficient than Alum for removing DOM due to their high efficiency for removing DOM fractions with fewer functional groups. The residual dissolved Al concentration depended on the total amount of reactive binding sites in DOM, and there was a strong linear correlation between residual dissolved Al and the total amount of reactive binding sites in DOM for Alum, while a weaker correlation was presented for PAC and Al13. This indicates that Ala was the dominant species to bind with the affinity sites in DOM to form residual dissolved Al.


Assuntos
Compostos de Alúmen/química , Substâncias Húmicas/análise , Espectrofotometria Ultravioleta/métodos , Poluentes da Água/isolamento & purificação , Adsorção , Sítios de Ligação , Distribuição Normal , Solubilidade
6.
Sci Total Environ ; 704: 135415, 2020 Feb 20.
Artigo em Inglês | MEDLINE | ID: mdl-31791775

RESUMO

Dissolved organic matter (DOM) plays a crucial role in terrestrial and aquatic carbon and biogeochemical cycles; however, molecular transformations between aquatic and terrestrial systems remain poorly understood due to the complexity and heterogeneity of DOM. In this study, we investigated the molecular diversity of aquatic DOM and adjacent soil derived water extractable organic matter (WEOM) from seven locations on Akimiski Island, Nunavut using a combination of absorbance spectroscopy and Fourier transform ion cyclotron mass spectrometry (FT-ICR-MS). Assigned elemental formula and Van Krevelen compositional analysis reveal compositional similarities in river, inland ponds and coastal pool sites for aquatic DOM and WEOM. More aromatic, oxygenated polyphenolic carbon rich molecules were found in aquatic DOM whereas WEOM was abundant in highly unsaturated aliphatic material. A total of 276 phenolic, unsaturated aliphatic, and vascular plant-derived polyphenolic molecules were identified as being conserved between WEOM and aquatic DOM at one river and two inland pond locations suggesting similar CHO sources from adjacent soils. Moreover, contributions of polyphenolic compounds in aquatic DOM and WEOM were greater at inland ponds than coastal pools, congruent with a greater aromaticity at inland sites. Our results highlight the similarities and differences in WEOM to aquatic DOM composition and how they range across surrounding watersheds that provide insight into the biogeochemical dynamics across a Canadian subarctic terrestrial-aquatic-continuum.


Assuntos
Monitoramento Ambiental , Substâncias Húmicas/análise , Compostos Orgânicos/análise , Nunavut , Solo/química
7.
Chemosphere ; 241: 125038, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31610455

RESUMO

The use of humic acid (HA) and fulvic acid (FA) as reinforcing agents to improve the efficiency of electrokinetic remediation (EKR) were investigated for the first time using an artificially contaminated soil. A series of soil leaching tests and bench-scale EKR experiments were performed to elucidate the mechanisms of As removed from artificially contaminated soil. The characterization of total reducing capacity (TRC) and functional group were carried out to reveal the difference of HA and FA. The observations demonstrated that with 0.1 M NaOH and KCl as the anolyte, using both HA and FA enhanced the efficiency of EKR. After 25 days of EKR, the removal efficiency of TAs in HA/FA-enhanced EKR was about 2.0-3.0 times greater than when unenhanced. Compared to HA, more As was removed in EKR with FA, which has more TRC and oxygen-containing groups. These EKR experimental results, with the support of data obtained from soil leaching test, indicate that competitive adsorption, reductive dissolution and complexation were the reasons why HA and FA promoted the release of As in the soil and further enhanced the remediation efficiency.


Assuntos
Arsênico/isolamento & purificação , Benzopiranos/farmacologia , Técnicas Eletroquímicas/métodos , Recuperação e Remediação Ambiental/métodos , Substâncias Húmicas/análise , Poluentes do Solo/isolamento & purificação , Adsorção , Poluentes do Solo/análise , Temperatura Ambiente
8.
Chemosphere ; 241: 124971, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31590024

RESUMO

Organophosphate triesters (OPEs) have caused great concern as a class of emerging environmental contaminants due to their widespread use and their toxicity to organisms. However, the phototransformation behavior of OPE is still not fully understood, which is important for understanding their environmental fate. In the present study, the photodegradation of tricresyl phosphate (TCP), one of the most widely detected OPEs in aqueous environments, was investigated including the direct photolysis and in the presence of several natural water factors, NO2-, Fe3+ and humic acid. The degradation process followed the pseudo-first-order kinetics, with rate constant increasing slightly with increasing initial TCP concentration. The presence of NO2- and Fe3+ was observed to promote the photochemical loss of TCP, while humic acid played a negative role on TCP transformation. Electron spin resonance (EPR) analysis showed that carbon-centered radical was produced in the photolysis process of TCP, and hydroxyl radical contributed to the promotion of rate constant for Fe3+ and NO2-. Four photolysis products were tentatively identified by HPLC-LTQ-Orbitrap MS analysis, and the possible degradation pathways of TCP were proposed. These findings provide a meaningful reference for the fate and transformation of OPEs in natural water.


Assuntos
Fotólise , Tritolil Fosfatos/química , Poluentes Químicos da Água/química , Cloretos/química , Compostos Férricos/química , Substâncias Húmicas/análise , Radical Hidroxila/análise , Cinética , Nitrito de Sódio/química , Tritolil Fosfatos/análise , Tritolil Fosfatos/efeitos da radiação , Água/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/efeitos da radiação
9.
J Chromatogr A ; 1609: 460453, 2020 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-31445801

RESUMO

Mesoporous structured molecularly imprinted polymers combined with restricted access materials (RAM-M-MIPs) were synthesized in this work, then RAM-M-MIPs were used as adsorbents in matrix solid phase dispersion (MSPD) to extract chlorpyrifos residues from soil. The RAM-M-MIPs with mesoporous structure increased adsorptive capacity and accelerated adsorption rate. At the same time, the RAM-M-MIPs with restricted access function showed good exclusion effect toward humic acid in the soil. In addition, the characteristics of RAM-M-MIPs were measured and the optimal experimental conditions of MSPD were explored. In MSPD, the extraction and clean-up procedures can be finished simultaneously, which saved the extraction time. The analyte eluted from soil was determined by LC-MS/MS. The recoveries were in the range of 93.5-106.1% and the relative standard deviations were in the range of 2.8-5.7% at the spiked soil levels of 0.10-10.00 ng g-1, the detection limit was 0.015 ng g-1. Based on these analytical validation results, the developed method can be a useful method to determine chlorpyrifos in soil.


Assuntos
Clorpirifos/isolamento & purificação , Impressão Molecular/métodos , Polímeros/química , Solo/química , Adsorção , Cromatografia Líquida , Substâncias Húmicas/análise , Cinética , Limite de Detecção , Porosidade , Reprodutibilidade dos Testes , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Espectrometria de Massas em Tandem , Termodinâmica , Fatores de Tempo
10.
Environ Pollut ; 256: 113465, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31679870

RESUMO

Fulvic acid (FA) significantly influences the bioavailability and fate of heavy metals in environments, while its acid-base characters and metal binding processes are still unclear. Here, spectroscopic techniques combined with multiple models (e.g., NICA-Donnan model) and two-dimensional correlation spectroscopy (2D COS) were applied to explore the proton and copper binding properties of FA sub-fractions (FA3-FA13). The charge densities, average contents of carboxylic and phenolic groups, average dissociation constants pKa1 and pKa2 of sub-fractions ranged 0-16 meq∙g∙C-1, 5.03-9.58 meq∙g∙C-1, 2.52-4.67 meq∙g∙C-1, 4.15-4.33 and 8.52-9.72, respectively. FA sub-fractions had a relatively narrow distribution of carboxyl group and a broad distribution of phenolic group. FA sub-fractions also exhibited roughly two phenolic hydroxyl groups per every 1-3 phenyl rings. Differential absorbance spectra (DAS) derived Gaussian bands were associated to the inter-chromophore interactions, the changes of molecular conformations and functional groups with copper addition. Differential spectra slopes (DSlope275-295&325-375) were more significant with higher copper concentration and copper amounts bonded to carboxylic groups. UV-Vis and fluorescence spectra with 2D heterospectral COS revealed the copper binding heterogeneities and sequential orders of chromophores and fluorophores, quantitatively confirming by the order of conditional stability constants (log KCu: 4.64-5.56). Salicylic-/polyhydroxyphenolic, hydroxyl and amino groups were strongly associated to the basic units for fluorophores. Sequential changes followed the order of humic-like→fulvic-like materials for FA3/FA5, humic-like→fulvic-like→tryptophan-like materials for FA7, and humic-like→tryptophan-like→fulvic-like→tyrosine-like materials for FA9/FA13. Spectroscopic techniques combined with various models (especially for 2D COS) are beneficial to elucidate the binding heterogeneity and sensitivity for metal-organic matters at the functional group level.


Assuntos
Benzopiranos/análise , Cobre/análise , Modelos Químicos , Cobre/química , Substâncias Húmicas/análise , Metais Pesados , Modelos Teóricos , Prótons , Espectrometria de Fluorescência
11.
Chemosphere ; 238: 124646, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31473523

RESUMO

Humic substances (HS) in the aqueous solutions can be considered as colloidal particles formed by amphiphilic units. HS form micelles-like structures at concentrations close to 5 g/L. However colloidal behavior of HS at concentrations below 100 mg/L is unknown. Using radiotracer assay we have shown that in this concentration range HS form rare adsorption layers at the liquid/liquid interface and penetrate into the organic phase with the distribution ratio close to 10-3. We found that pH and HS molecular weight strongly influence on the distribution ratio but do not significantly change the adsorption. Furthermore, colloidal properties of HS are strongly depending on its origin: the highest surface activity was shown for HS separated from peat and the least was observed for HS separated from soils. We anticipate our assay to be a helpful tool for detailed analysis and modeling HS and humic-like materials colloidal behavior in the environment.


Assuntos
Substâncias Húmicas/análise , Soluções/química , Adsorção , Coloides , Concentração de Íons de Hidrogênio , Micelas , Peso Molecular , Solo , Trítio/análise
12.
Chemosphere ; 239: 124703, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31526999

RESUMO

In recent years, precise environment supervision has gradually become vital in water pollution control, which requires the clear identification of dissolved organic matters (DOM) in wastewater. Metalworking fluid (MWF) is a type of wastewater with high toxicity. Over ten million m3 of MWF is discharged per year. However, its DOM characteristics have not yet been systematically investigated. Therefore, in this study, the fluorescent DOM (FDOM) of MWF was firstly characterized by excitation-emission matrix-parallel factor analysis (EEM-PARAFAC) and high-performance liquid chromatography (HPLC). Three fluorescent components (C1-C3) of the MWF from three metalworking plants (BO, TH, and YD) were identified. The peaks measured for C1 and C3 were attributed to tryptophan-like (Peak T) and humic/fulvic acid-like (Peak A + C) peaks, respectively, and the peaks at C2 were identified as humic-like (Peak A + M) or tryptophan-like (Peak T) peaks. There were differences in the C2 and C3 components of MWF from the three metalworking plants. The FDOM of MWF from the three metalworking plants exhibited similar polarity, but different apparent molecular weight distributions. In addition, the highest intensities of the three fluorescent peaks were sensitive to variations in the pH, humic acid (HA) concentrations, and metal ion levels (Cu2+, Fe3+, and Ni2+). The findings of this study not only indicate the FDOM characteristics of MWF, but also provide a promising method and valuable guidance for the practical monitoring of MWF in natural water bodies.


Assuntos
Fluorescência , Substâncias Húmicas/análise , Águas Residuárias/toxicidade , Cromatografia Líquida de Alta Pressão , Análise Fatorial , Instalações Industriais e de Manufatura , Metais/análise , Espectrometria de Fluorescência/métodos , Águas Residuárias/análise
13.
Chemosphere ; 240: 124977, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31726600

RESUMO

In this study, Fe3O4 and microwave (MW) were combined to activate persulfate (PS) for the removal of organic matter, resulting in the enhanced degradation of p-nitrophenol (PNP) in solution. During the preparation of Fe3O4, the effect of sodium acetate was examined, and the results showed that the concentration of sodium acetate had little effect on the catalytic activity of the Fe3O4/PS/MW system but did have an effect on the Fe3O4 yield. In addition, with regards to the representative environmental factors, the degradation experiment showed that humic acid and the co-existing anions of chloride, sulfate, nitrate, and phosphate had little effects on p-nitrophenol removal; however, carbonate had a negative effect. In addition, the Fe3O4/PS/MW system performed well in the initial pH range of 3.0-9.0. According to the quenching experiment and electron paramagnetic resonance (EPR) detection, sulfate radicals and a minority of hydroxyl radicals play dominant roles in the degradation process. In addition, the role of Fe3O4 was confirmed to take part in the degradation process by X-ray photoelectron spectroscopy (XPS) analysis. Because of the good performance observed in the water matrices of tap water and the Songhua River, these results demonstrate the potential application of the Fe3O4/PS/MW system for wastewater treatment.


Assuntos
Compostos Férricos/química , Micro-Ondas , Nitrofenóis/química , Poluentes Químicos da Água/química , Catálise , Compostos Férricos/isolamento & purificação , Compostos Férricos/efeitos da radiação , Substâncias Húmicas/análise , Radical Hidroxila/química , Sulfatos/química , Água/química , Poluentes Químicos da Água/análise
14.
Chemosphere ; 240: 124808, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31546188

RESUMO

The aim of this study was to evaluate the long-term effect of urban and green waste compost exogenous organic matter (EOM) on soil dissolved organic matter (DOM). A luvic cambisol was amended 7 years before the study. DOM was investigated along a soil profile down to 1 m depth regarding seasonal variations (autumn and spring). DOM sampled by suction cups was characterized using dissolved organic carbon (DOC) content and excitation emission matrix (EEM) fluorescence. The variability of DOM concentrations was pronounced but no major change in composition was determined. The results obtained, reinforced by statistical analysis, showed that the DOM quality was mainly influenced by soil management (organic matter amendment) whereas the quantity mainly depended on the season (heavy precipitation event). DOM humic characteristics were strongly dependent on amendment and changed with depth but was not affected by the season. Long term effect of compost organic matter was highlighted after a 7-years amendment.


Assuntos
Monitoramento Ambiental , Substâncias Húmicas/análise , Poluentes do Solo/análise , Solo/química , Estações do Ano
15.
Sci Total Environ ; 698: 134133, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31505348

RESUMO

The series of breakthroughs that have occurred within the realm of nanotechnology have been the source of several new products and technological interventions. One of the most salient examples in this regard is the widespread employment of titanium dioxide (TiO2) nanoparticles across a range of consumer goods. Given that waste is generated at every stage of the consumer-product cycle (from production to disposal), many items with TiO2 nanoparticles are likely to end up being discarded into water bodies. In order to understand the interaction of TiO2 NPs with aquatic ecosystem, the ecological fate and toxicity of TiO2 NPs was studied by exposing zebrafish embryos to a combination of abiotic factors (humic acid and clay) to assess its effect on the development of zebrafish embryos. The physiological changes were correlated with genetic marker analysis to holistically understand the effect on embryos development. Derjaguin-Landau-Verwey-Overbeek (DLVO) theory was used to analyze the interaction energy between TiO2 NPs and natural organic matter (NOM) for understanding the aggregation behavior of engineered nanoparticles (ENPs) in media. The study revealed that combination of HA and clay stabilized TiO2 NPs, compared to bare TiO2 and HA or clay alone. TiO2 NPs and TiO2 NPs + Clay significantly altered the expression of genes involved in development of dorsoventral axis and neural network of zebrafish embryos. However, the presence of HA and HA + clay showed protective effect on zebrafish embryo development. The complete system analysis demonstrated the possible ameliorating effects of abiotic factors on the ecotoxicity of ENPs.


Assuntos
Argila/química , Nanopartículas Metálicas/toxicidade , Titânio/toxicidade , Animais , Embrião não Mamífero , Desenvolvimento Embrionário/efeitos dos fármacos , Substâncias Húmicas/análise , Nanopartículas Metálicas/química , Titânio/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/toxicidade , Peixe-Zebra
16.
Chemosphere ; 238: 124679, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524617

RESUMO

Biochar amendment for compost stabilization of divergent biowastes is gaining considerable attention due to environmental, agronomic and economic benefits. Research to date exhibits its favorable physico-chemical characteristics, viz. greater porosity, surface area, amount of functional groups, and cation exchange capacity (CEC), which allow interface with main nutrient cycles, favor microbial activities during composting, and improve the reproduction of earthworms during vermicomposting. Biochar amendment during composting and vermicomposting of biowastes boosts physico-chemical properties of compost mixture, microbial activities and organic matter degradation; and reduces nitrogen loss and emission of greenhouse gases (GHGs). It also improves the quality of final compost by increasing concentration of plant available nutrients, enhancing maturity, decreasing composting duration and reducing the toxicity of compost. Due to these characteristics, biochar could be considered a beneficial additive for the stabilization of different biowastes during composting and vermicomposting processes. Hence, good quality vermicompost, efficient recycling and management of biowastes could be achieved by addition of biochar through composting and vermicomposting.


Assuntos
Carvão Vegetal/química , Substâncias Húmicas/análise , Substâncias Húmicas/microbiologia , Solo/química , Resíduos Sólidos/análise , Animais , Compostagem/métodos , Nitrogênio/análise , Oligoquetos
17.
Chemosphere ; 238: 124683, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524620

RESUMO

The combination of the filtration capacity of zooplankton (e.g. Daphnia) with the nutrient removal capacity of bacterial/algal biofilm in a zooplankton-containing reactor could provide a natural-based alternative for wastewater treatment. A laboratory-scale zooplankton-based reactor was tested at different HRTs resulting in a significant reduction in nutrient concentrations in wastewater when the system was operated at HRTs longer than 1.1 days (preferably of between 2 and 4 days). However, the presence of high concentrations of organic matter (>250 mg COD L-1) in the wastewater inhibited zooplankton activity, limiting its use to tertiary treatment. Therefore, in combination with other natural treatments that can perform primary and secondary treatments, zooplankton may provide a solution for wastewater clarification and nutrient polishing. The effect of a common metal such as copper on the filtration capacity of Daphnia was also evaluated. Daphnia, as well as the whole zooplankton-based reactor, adapted to copper concentrations of up to 70 µg Cu L-1 but an overload of 380 µg Cu L-1 for two-weeks severely affected the biological system.


Assuntos
Bactérias/metabolismo , Reatores Biológicos , Daphnia/metabolismo , Águas Residuárias/química , Zooplâncton/metabolismo , Animais , Biofilmes/crescimento & desenvolvimento , Cobre/análise , Filtração/métodos , Substâncias Húmicas/análise
18.
Chemosphere ; 238: 124691, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524626

RESUMO

In recent years, forward osmosis (FO) has represented numerous potential applications in safe water production. In this study, we improved the performance of FO thin film composite (TFC) membranes for the removal of trace organic compounds (TOrCs) by tuning the chemistry of its top active layer. The TFC membranes were synthesized by interfacial polymerization (IP) reaction between amine-containing monomers, e.g., meta-phenylene diamine (MPD) or para-phenylenediamine (PPD), and an acid chloride monomer, e.g., trimesoyl chloride (TMC). Owing to three free amine functionals over main core, melamine was used in the amine monomers solution to increase cross-linking among polyamide chains. Chemical and morphological characterization of the prepared membranes confirmed that melamine was successfully incorporated into the chemical structure of the top PA layer. Two agricultural toxic materials (atrazine and diazinon) were used to investigate the capability of the newly fabricated membranes in the removal of TOrCs. The obtained results showed that melamine-improved FO membranes provided higher atrazine and diazinon rejections in two different FO membrane configurations, including active layer facing feed solution (ALF) and active layer facing draw solution (ALD). The highest rejections of both diazinon (99.4%) and atrazine (97.3%) were achieved when the melamine modified MPD-based membrane served in ALF mode with 2 M NaCl as a draw solution.


Assuntos
Substâncias Húmicas/análise , Osmose/fisiologia , Purificação da Água/instrumentação , Purificação da Água/métodos , Atrazina/análise , Diazinon/análise , Membranas Artificiais , Nylons/química , Fenilenodiaminas/química , Polimerização , Cloreto de Sódio/química , Triazinas/química , Ácidos Tricarboxílicos/química , Água/química
19.
Sci Total Environ ; 700: 134360, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31629259

RESUMO

The characteristics of dissolved organic matter (DOM) in inflowing river, flowing into drinking water, have profound influences on the quality and safety of water. Here, ultraviolet-visible (UV-vis) spectroscopy and three-dimensional fluorescence (EEM) spectroscopy were combined to investigate the spatiotemporal variations of DOM in Nanfei River flowing into Chaohu Lake in China. 24 water samples and 24 surface sediments samples (including dry-to-wet transition season and wet season in 2018) were collected from different types of outlets. Parallel factor analysis (PARAFAC) model and correlation analysis were conducted to identify the primary sources of DOM. Two humic-like components (C1 235-250 nm/385-430 nm and C3 255-270 nm/455-510 nm) and one tryptophan-like component (C2 270-290 nm/320-350 nm) were effectively identified by PARAFAC model. The results showed DOM concentration presented significant spatiotemporal variations. The concentration was much lower in water than in surface sediments in dry-to-wet transition season, but higher in the wet season. Fluorescence index (FI), biological index (BIX) and humification index (HIX) were used to judge characteristic of DOM origination. These indexes indicated that, DOM in Nanfei River had both the characteristics of humus and autogenous, but neogene autogenic feature was stronger, which was largely due to mixture of water, resuspension and desorption of DOM in sediments and photochemical degradation. In addition, the characteristic parameter of molecular mass of DOM (the values of M) had an obvious linear relationship with the fluorescence intensity ratio of fulvic acid-like to humic acid-like (C1/C3), indicating that macromolecular substances could be removed by adding or improving membrane treatment. These provided technical support for improving quality and comprehensive treatment of drinking water sources.


Assuntos
Monitoramento Ambiental/métodos , Substâncias Húmicas/análise , Poluentes da Água/análise , Benzopiranos , China , Água Potável/química , Análise Fatorial , Fluorescência , Rios/química
20.
Ecotoxicol Environ Saf ; 188: 109834, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31683045

RESUMO

Monitoring dissolved organic matter (DOM) content in aquatic environments is crucial for not only understanding the dynamics of heavy metals but also predicting their bioavailability. Fluorescence spectroscopy is typically employed to characterise DOM. Here, the interaction between DOM and trace metals was investigated by combining excitation-emission matrix (EEM) quenching with two-dimensional Savitzky-Golay second-order differentiation (2D-SG-2nd-df) analysis. The 2D-SG-2nd-df analysis decomposed the EEM spectra of commercial humic acid (HA) samples into six separate fluorescence peaks, which agreed with the results obtained through conventional parallel factor (PARAFAC) analysis. Compared with PARAFAC modeling, the 2D-SG-2nd-df approach provided more valid and reliable results when the dataset contained distinct samples. Moreover, since the results obtained from 2D-SG-2nd-df for each sample are independent, shifts in the peak wavelength can be reproduced more efficiently using this method. Triplicate titration experiments showed clear differences in HA-copper interactions for samples with different HA composition and molecular weight. The binding strength between copper and low-molecular-weight DOM in water was weaker than that observed for high-molecular-weight DOM. The results obtained in this study will serve as a basis for applying 2D-SG-2nd-df not only to DOM but also to other samples studied using EEM measurements.


Assuntos
Cobre/química , Substâncias Húmicas/análise , Modelos Químicos , Oligoelementos/química , Poluentes Químicos da Água/química , Análise Fatorial , Íons , Peso Molecular , Solubilidade , Espectrometria de Fluorescência/métodos
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