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1.
Chemosphere ; 244: 125626, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32050356

RESUMO

The aquatic plants Iris pseudacorus L., Canna indica L. and Lythrum salicaria L. have been proved to be potential choices for nitrogen removal. However, little is known about microbial diversity for the improvement of nitrogen removal (nitrification and denitrification) in stormwater bioretention cells with the above plants. In this study, batch experiments were conducted to investigate nitrogen removal, substrate layer status, and bacterial community structure to understand microbial diversity and evaluate its effects on performances of nitrogen removal. Ammonia nitrogen removal in the bioretention cell with Lythrum salicaria L. was the highest (88.1%), which was consistent with oxidation reduction potential (ORP) in the bioretention cells. Whilst, removals for both total nitrogen and nitrate were the highest in the bioretention cell with Canna indica L., which was in line with urease activity in the mentioned cells. The used plants had different impact on top 11 dominant microflora at phylum level in the used bioretention cells. Ramlibacter and Nitrosomonadaceaea were both responsible for the difference of nitrogen removal in the bioretention cells with three aquatic plants, suggesting the enhancement of the above dominant microflora could strengthen nitrogen removal in the used bioretention cells.

2.
Huan Jing Ke Xue ; 40(9): 4238-4243, 2019 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854890

RESUMO

This study tested a strategy in simulated column systems to control methane emissions from algal bloom waters using the combined technology of algae sedimentation and sediment capping. The results demonstrated that the synergy of algal sedimentation and sediment capping can effectively improve the water environment and reduce methane emissions; however, the improvement rate differed among capping materials. The use of activated carbon yielded better performance on the water environment improvement and methane emission control than soil and zeolite. Compared with the control system, the dissolved oxygen and redox potential in the water were increased from<2.5 mg·L-1 to 3.1 mg·L-1 and from<100 mV to 174 mV, respectively. In addition, the redox potential in the surface sediment was reversed from -125 mV to 168 mV after algal sedimentation with subsequent activated carbon capping. As a result, methane emissions in the algal sedimentation-activated carbon capping systems were decreased by 90.2% over the incubation period relative to the control system. This study provides useful insights into methane emission control in eutrophic waters.


Assuntos
Eutrofização , Lagos , Metano , Sedimentos Geológicos , Oxigênio , Solo
3.
Artigo em Inglês | MEDLINE | ID: mdl-31520385

RESUMO

Inland waters are considered hotspots of greenhouse gas (GHG) emissions and have been extensively researched. Static chamber (STAT) and thin boundary layer (BLE) are two commonly used methods for analyzing diffusive GHG emissions from inland waters. However, the STAT method is often disturbed by GHG bubbles; meanwhile, many kinds of headspace gas are used in the BLE method, but the differences between their diffusive GHG emission analysis results are not understood. In this study, the chamber in the STAT method was modified to combat the disturbances from GHG bubbles, and the typically used gases for the BLE method, namely, pure nitrogen, air, and filtered air, were comparatively studied. Results demonstrated that the modified chamber could effectively prevent the invasion of GHG bubbles; it increased the success rate from 67 to 90% in the field test, with no obvious impacts on the results of the GHG emission analyses. The use of air and filtered air in the BLE method yielded the lower values of GHG emissions relative to pure nitrogen, and this finding was potentially attributed to the inhibition effects of the residual GHGs and high humidity in air and filtered air on the extraction of diffusive GHGs from the surface water. This study improved the commonly used methods for diffusive GHG emission analysis, and the current findings are beneficial to the study of GHG emissions from inland waters.

4.
Sci Total Environ ; 676: 447-454, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31048174

RESUMO

Recently, both sand and fly ash have been used for nutrient removal in bioretention systems. However, the improvement in nutrient removal was hampered by a lack of data about of microbial diversity and metabolism effects in the mentioned materials based bioretention systems. Therefore, a mixture with sand, soil and fly ash (1:1:1) was selected as the base in bioretention systems. The investigation of microbial diversity implied that 11 dominant microflora were found, which changed weakly at phylum level but significantly at genus level. The analysis for both urease and extracellular polymer (EPS) showed that urease levels increased with the increase of submerged zone height, which was in line with nitrogen removal, while EPS had the opposite situation. Overall evaluation of microbial role suggested that the enhancement of dominant microflora in the used bioretention systems, like Chloroflexi and Nitrospirae, could strengthen nitrogen removal.


Assuntos
Microbiologia Ambiental , Eliminação de Resíduos Líquidos/métodos , Adsorção , Biodiversidade , Cinza de Carvão , Nitrogênio , Fósforo , Dióxido de Silício , Solo
5.
Environ Geochem Health ; 41(6): 2697-2708, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31140134

RESUMO

Road-deposited sediment (RDS) has been identified as both the source and sink of various pollutants. In this study, the highway-deposited sediment (HDS) in Spring, Summer, Autumn and Winter was characterized. On average, the mass proportions of particles with the size of 830-4750 µm, 500-830 µm, 250-500 µm, 150-250 µm, 63-150 µm and < 63 µm were 23.6 ± 8.6%, 16.9 ± 3.4%, 28.4 ± 3.5%, 10.0 ± 4.3%, 15.7 ± 5.8% and 5.3 ± 2.0%, respectively, wherein the HDS of 63-830 µm accounted for 71% of the total mass load. It was observed that the particle size distribution of HDS could be described using the gamma distribution function based on gravimetric and cumulative basis (R2 (determination coefficient) = 0.9960-0.9995). The bulk pollutant contents of HDS showed seasonal variation with the mean of COD (chemical oxygen demand), nitrogen, phosphorus, Zn (zinc), Pb (lead) and Cd (cadmium) as 57 g/kg, 839 mg/kg, 97 mg/kg, 627 mg/kg, 110 mg/kg and 1.00 mg/kg and the highest COD of 83 g/kg in Autumn, nitrogen 1164 mg/kg Autumn, phosphorus 133 mg/kg Winter, Zn 801 mg/kg Summer, Pb 133 mg/kg Spring and the highest Cd of 1.36 mg/kg in Summer, respectively. The contents of Zn, Pb and Cd in HDS were significantly above their local soil background values. Moreover, the size fractional pollutant contents overall increased as particles' size increased. Averagely, 40-52% pollutant loads were associated with the particles < 250 µm, which can be moved easily by runoff. This study suggests that the behaviors of HDS different from city RDS should be considered as nonpoint source pollution control is performed.


Assuntos
Poluentes Ambientais/análise , Sedimentos Geológicos/análise , Análise da Demanda Biológica de Oxigênio , China , Cidades , Monitoramento Ambiental , Poluentes Ambientais/química , Sedimentos Geológicos/química , Nitrogênio/análise , Tamanho da Partícula , Fósforo/análise , Estações do Ano
6.
Sci Total Environ ; 676: 823-833, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31076206

RESUMO

Biotic and abiotic pathways for the transformation of phosphorus (P) in the sediment of Taihu Lake, a eutrophic shallow freshwater lake in southeastern China, were studied using the oxygen isotope ratios of phosphate (δ18OP) along with sediment chemistry, X-ray diffraction, and 57Fe-Mössbauer spectroscopic methods. The results showed that δ18OP values of sediment P pools significantly deviated from equilibrium and thus allowed distinguishing potential P sources or pathways of transformation. Isotope values of authigenic P being lighter than equilibrium suggests the re-mineralization of organic matter and subsequent precipitation of apatite as the major pathway of formation of authigenic P. The δ18OP values of the Al-bound P pool (18.9-23.5‰) and ferric Fe-bound P (16.79-19.86‰) could indicate potential terrestrial sources, but the latter being closer to equilibrium values implies partial overprinting of potential source signature, most likely due to reductive dissolution and release of P and followed by partial biological cycling before re-sorption/re-precipitation with newly formed ferric Fe minerals. Oxic/anoxic oscillation and dissolution/re-precipitation reactions and expected isotope excursion are corroborated by sediment chemistry and Mössbauer spectroscopic results. These findings provide improved insights for better understanding the origin and biogeochemical cycling of P associated with eutrophication in shallow freshwater lakes.

7.
Environ Sci Pollut Res Int ; 26(7): 6898-6910, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30635880

RESUMO

In order to control nitrogen (N) pollution of Lake Taihu, China, we studied the spatial and temporal distribution characteristics of inorganic N in inflowing rivers polluted by industry, agriculture, and domestic sewage during low, moderate, and high flow periods. The results showed that dissolved total nitrogen (DTN) was the main fraction of total nitrogen (TN) input from these rivers. Inflowing rivers had distinct impacts on TN, DTN, ammonium N (NH4+), and nitrate N (NO3-) concentrations of Lake Taihu during the low flow period. Particulate nitrogen (PN) had an impact on Lake Taihu during the three flow periods and all the three types of rivers would increase PN concentration in the lake. Rivers polluted by agriculture had the greatest impact on Lake Taihu's TN, DTN, NO3-, and dissolved inorganic N (DIN) concentrations, while rivers polluted by industry had the greatest impact on NH4+ concentration. Therefore, agriculture and industry should be key targets for nutrient reductions. The in-lake N concentrations were higher than those of inflowing rivers during moderate and high flow periods.


Assuntos
Monitoramento Ambiental , Nitrogênio/análise , Poluentes Químicos da Água/análise , Agricultura , China , Poluição Ambiental , Eutrofização , Lagos , Nitratos , Rios/química , Esgotos
8.
Environ Technol ; : 1-10, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30382010

RESUMO

Constructed wetlands (CWs) are natural-friendly method to eliminate the pollutants stormwater pollutants. For this study, a pilot-scale treatment system consisting of a sedimentation tank (ST) and five recirculated fill-and-drain wetlands (namely CW-1, CW-2, CW-3, CW-4 and CW-5) were constructed to treat the first-flush from the impervious road. From bottom to top, the main substrates of CWs were selected as 0 cm woodchip + 60 cm pumice for CW-1, 15 cm woodchip + 45 cm pumice for CW-2, 30 cm woodchip + 30 cm pumice CW-3, 45 cm woodchip + 15 cm pumice CW-4 and 60 cm woodchip + 0 cm pumice for CW-5. During the operational period, the reduction efficiencies of TSS, total COD, total nitrogen and total phosphorus were 89-100%, 52-100%, 31-87% and 72-100% by CW-1, 92-100%, -27% to 78%, 8-85%, 49-94% by CW-2, 89-100%, -97% to 77%, -29% to 86%, -46% to 94% by CW-3, 89-100%, -115 to 69%, -21% to 99%, 35-94% by CW-4 and 59-100%, -342%to 88%, -20% to 88%, -77% to 99% by CW-5, respectively. Overall, the reduction efficiency, except for nitrogen, declined as the amount of woodchip increased. As excepted, the employment of woodchip improved denitrification via providing with carbon sources, resulting in low NO3-N but unfavourable COD concentrations in the effluent. And the combination use of woodchip and pumice as CW-3 or CW-4 is suggested, whereas the specific amount of woodchip and pumice should be determined based on the regional environmental goal.

9.
Chem Commun (Camb) ; 54(96): 13579-13582, 2018 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-30444509

RESUMO

A new class of 2D fewer-layer π-conjugated conductive metal-organic nanosheets was developed via the Langmuir-Blodgett method, exhibiting ultrahigh mass activity (64.63 A mg-1, 1.7 V vs. RHE) and stability for electrochemical oxygen evolution reactions (OER).

10.
Exp Ther Med ; 16(2): 847-855, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30116338

RESUMO

Injury of hippocampal neurons in status epilepticus (SE) SD rats kindled by pentylenetetrazol (PTZ) were studied, and the changes of apoptosis neurons, protein expression of Bad and Bcl-2 alone and combined application of phosphatidyl inositol 3-kinase (PI3K) inhibitor LY294002 and recombinant human erythropoietin (rHuEpo) were evaluated for the possible mechanisms of rHuEpo. The SE rats kindled by the PTZ were randomly divided into normal control group [normal saline (NS)], model group (PTZ + NS), rHuEpo treated group (PTZ + rHuEpo), LY294002 treated group (PTZ + LY294002 + rHuEpo) and LY294002 control group (rHuEpo + PTZ + DMSO). Apoptosis of hippocampal neurons was detected by TUNEL method; expression of phosphorylation protein kinase B (p-PKB/p-Akt), Bcl-2 and Bad were detected by immunohistochemistry; the expression of Bcl-2 mRNA, Bad mRNA in hippocampal neurons of rats were detected through reverse transcription polymerase chain reaction (RT-PCR); the expression of Akt, p-Akt and Bcl-2, Bad protein in hippocampal neurons of rats were detected by western blotting. The amount of apoptotic neurons was less in the rHuEpo treated group and the LY294002 control group than in the LY294002 treated group (P<0.05). The expression of p-Akt protein and Bcl-2 protein increased while the Bad protein decreased significantly in the rHuEpo treated group and the LY294002 control group compared with the LY294002 treated group (P<0.05). The expression of Bad protein and Bad mRNA in hippocampus increased while the p-Akt, Bcl-2, Bcl-2 mRNA decreased significantly in the LY294002 treated group compared with the rHuEpo treated group (P<0.05). The PI3K/Akt signaling pathway is one of the pathways of rHuEpo neuroprotective effects and was confirmed from both the of positive and negative aspects. rHuEpo regulates the expression of mitochondrial apoptotic pathway related factors Bad and Bcl-2 to inhibit apoptosis and promotes neuronal survival.

11.
Onco Targets Ther ; 11: 4339-4344, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30100739

RESUMO

Purpose: In this paper, the association between polymorphisms of IFN-γ +874T/A (rs2430561), IFN-γR1 -56 T/C (rs2234711), IFN-γR1 +95 C/T (rs7749390), and IFN-γR1 -611A/G (rs 1327474) and human papillomavirus (HPV) susceptibility was investigated in rural women from Luohe, Henan, China. Patients and methods: A total of 520 rural women were enrolled from Luohe, including 260 with HPV infection and mild dysplasia or less and 260 without HPV infection. Single-nucleotide polymorphisms (SNPs) of IFN-γ +874T/A, IFN-γR1 -56 T/C, IFN-γR1 +95 C/T and IFN-γR1 -611A/G were genotyped using TaqMan Pre-Designed SNP Genotyping Assays. Serum IFN-γ levels were measured using Human IFN-γ Quantikine ELISA Kit. Multivariate logistic regression analysis was performed to identify the SNPs associated with HPV susceptibility. Serum IFN-γ levels were compared between different genotypes. Results: The polymorphism of IFN-γ +874T/A was associated with HPV susceptibility and +874A carriers had an increased risk. Moreover, the odds ratio was higher in +874 AA carriers than in +874 AT carriers (1.672 vs 2.874). Serum IFN-γ levels were highest in IFN-γ +874 TT carriers, intermediate in AT carriers, and lowest in AA carriers (2.86±1.14 vs 1.57±0.79 vs 0.41±0.22 pg/mL, all P<0.05). Conclusion: The polymorphism of IFN-γ +874T/A was associated with HPV susceptibility in rural women from Luohe, Henan, China, and +874A carriers had an increased risk. The possible mechanism was that +874A carriers had a low production of IFN-γ.

12.
Environ Sci Pollut Res Int ; 25(9): 8943-8950, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29332273

RESUMO

Surface-deposited sediment in urban areas is an essential environmental medium for assessing nutrient contamination. The total nitrogen (TN) and total phosphorus (TP) pollution associated with surface-deposited sediments can be transported into urban water bodies by runoff and can cause eutrophication of those water bodies. By analyzing the samples collected on roof surfaces and road surfaces, this study provides a comparison of the differences in TN and TP pollution loading in sediments on these two different impervious surface materials. Also, an assessment of the ecological risk of nutrients in surface-deposited sediments with respect to grain size fraction was performed. The results indicate that the TN and TP pollution loading in both road-deposited sediments and roof-deposited sediments indicated an asymmetric "W" trend along with grain size fraction, and both road-deposited sediments and roof-deposited sediments had the highest TN and TP pollution contribution when the particle size is between 250 and 500 µm. TN in roof-deposited sediments has high ecological risk when the particle size is less than 250 µm. These findings help to provide guidance for the management of surface-deposited sediment pollution.


Assuntos
Nitrogênio/análise , Fósforo/análise , China , Ecologia , Poluição Ambiental , Eutrofização , Sedimentos Geológicos , Nitrogênio/química , Tamanho da Partícula , Fósforo/química , Medição de Risco
13.
Curr Eye Res ; 43(2): 266-272, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29135355

RESUMO

PURPOSE: To evaluate the effects of carotid artery angioplasty and stenting (CAAS) on patients who were diagnosed with ocular ischemic syndrome (OIS). METHODS: Sixty-four eyes of 64 OIS patients with ipsilateral internal carotid artery stenosis ≥70% were included in the study. The study eyes were divided into two groups according to the presence of iris neovascularization: NVI-absent group and NVI-present group, with 32 eyes, respectively. All patients received ocular treatment modality according to the presence of non-perfusion area (pan-retinal photocoagulation) and intraocular pressure (medical treatment included timolol maleate eye drops combined with brinzolamide eye drop; trabeculectomy and cyclophotocoagulation). All patients went through CAAS surgery for treatment of internal carotid artery stenosis. Best-corrected visual acuity (BCVA); intraocular pressure (IOP), slit lamp examination, iris fluorescence angiography, fundus fluorescein angiography and color Doppler ultrasound of the internal carotid artery (ICA), ophthalmic artery (OA), central retinal artery (CRA), and short posterior ciliary arteries (PCA) were performed pre-operatively and 1 month, 3 months, 6 months, and 12 months post-operatively. RESULTS: There was no significant BCVA change postoperatively in the NVI-absent group, while postoperative BCVA in the INV-present group decreased significantly. There was no significant BCVA difference at pre-operative and 1month post-operative follow-up between the two groups. However, post-operative BCVA of NVI-present group starting from 3-months follow-up was significantly worse than NVI-absent group. Arm-retinal artery circulation time and arteriovenous circulation time decreased significantly in NVI-absent group, while showed no statistical difference in NVI-present group during the 12-months follow-up. Postoperative peak systolic velocity (PSV) of the ophthalmic artery, the central retinal artery, and short posterior ciliary artery showed significant increases at 1 month, 3 months, 6 months and 12 months follow-up in both groups. CONCLUSION: CAAS can greatly improve ocular blood in OIS patients with and without iris neovascularization. However, CAAS improved BCVA only in patients without iris neovascularization.


Assuntos
Angioplastia com Balão , Artéria Carótida Interna/fisiopatologia , Estenose das Carótidas/terapia , Olho/irrigação sanguínea , Isquemia/fisiopatologia , Artéria Oftálmica/fisiologia , Stents , Antagonistas Adrenérgicos beta/uso terapêutico , Idoso , Velocidade do Fluxo Sanguíneo/fisiologia , Inibidores da Anidrase Carbônica/uso terapêutico , Artéria Carótida Interna/diagnóstico por imagem , Estenose das Carótidas/diagnóstico por imagem , Estenose das Carótidas/fisiopatologia , Quimioterapia Combinada , Feminino , Humanos , Pressão Intraocular/efeitos dos fármacos , Iris/irrigação sanguínea , Fotocoagulação a Laser , Masculino , Neovascularização Patológica/fisiopatologia , Estudos Prospectivos , Vasos Retinianos/fisiologia , Sulfonamidas/uso terapêutico , Tiazinas/uso terapêutico , Timolol/uso terapêutico , Ultrassonografia Doppler em Cores , Acuidade Visual
14.
Environ Sci Pollut Res Int ; 24(14): 12871-12881, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28364209

RESUMO

Surface-deposited sediment in urban area is an essential environmental medium for assessing heavy metal contamination. A total of 10 sampling trips were conducted to collect road-deposited and roof-deposited sediments for the comparison of nickel (Ni), copper (Cu), cadmium (Cd), lead (Pb), zinc (Zn), and chromium (Cr) contamination characteristics. Results indicated that roof sediment appeared to have a finer size distribution than road sediments. Roof sediment indicated higher metal concentration and lower surface loading than road sediment. The impact of particle size on heavy metal contamination was quantified by using the developed pioneering term of finer particle effect factor; it differed according to surface types and grain size fraction. Particles in individual grain size fraction showed different contribution to the surface loading for bulk sediments. No consistent trend was found for the grain size fraction loading along with grain size for the studied heavy metals for road sediments. In contrast, an asymmetric "W" trend was observed for the roof sediments, and it had the following results: Fraction of <63 and 250-500 µm showed higher loading, while fraction of 90-125 and >850 µm indicated the smaller loading. Findings above facilitated the appropriate management practice selection for the treatment of surface-deposited sediments.


Assuntos
Monitoramento Ambiental , Sedimentos Geológicos , Cádmio , Metais Pesados , Poluentes Químicos da Água , Zinco
15.
Huan Jing Ke Xue ; 37(4): 1404-12, 2016 Apr 15.
Artigo em Chinês | MEDLINE | ID: mdl-27548962

RESUMO

Different forms of phosphorus from the upper reaches of river to lower reaches of river in nine rivers were analyzed to clarify the pollution characteristics of industrial effluent, agriculture effluent and sanitary wastewater to Lake Taihu in February (low water period), May (average water period) and August (abundant water period) of 2009. The results showed that total phosphorus (TP) dissolved total phosphorus (DTP) and soluble reactive phosphorus ( SRP) mass concentration all showed decreasing trend while enzymatic phosphorus (EHP) mass concentration increased with the increase of algal biomass from low water period to abundant water period. Mass concentrations of several forms of phosphorus were all the highest in the rivers impacted by sanitary wastewater, but sanitary wastewater's self-purification capabity from the upper reaches of river to lower reaches of river was the best, and the pollution to Lake Taihu was the lowest. Pollution from rivers impacted by industrial effluent was the highest. Mass concentration of EHP was higher than that of SRP in most cases, so EHP played an important role in Cyanbacterial harmful algal blooms events in Lake Taihu.


Assuntos
Monitoramento Ambiental , Fósforo/análise , Rios/química , Poluentes Químicos da Água/análise , Agricultura , China , Cianobactérias , Eutrofização , Resíduos Industriais , Lagos , Análise Espaço-Temporal , Águas Residuárias
16.
Environ Technol ; 37(5): 577-89, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26209268

RESUMO

This study was carried out to identify the filter performance of fibre filter module treating high-turbidity water at extremely high filtration rates (1000-2500 m/day). The effects of filter aid chemical (polyaluminium chloride (PAC)), filtration rate and particles size on filter performance were investigated. It was found that PAC was a crucial factor influencing the separation process. Even though the optimum PAC dose for the raw water with turbidity of 50 nephelometric turbidity units (NTU) was 0.5 mg/L, the turbidity removal efficiencies were similar as the raw water turbidity was no more than 50 NTU. As expected, the filter performance was negatively affected by the increased filtration rate. However, the turbidity removal efficiency at an extremely high filtration rate still was amazing and attractive (∼80% at 2500 m/day). Moreover, the D50 and uniformity coefficient of the particles in raw water were not the factors greatly affecting the filter performance. The empirical model for the filter processes of granular filters did not work; therefore, an empirical model towards fibre filters at a high flow rate was suggested, which can be used to predict the treatment performance.


Assuntos
Hidróxido de Alumínio/química , Filtração/métodos , Purificação da Água/métodos , Filtração/instrumentação , Nefelometria e Turbidimetria , Tamanho da Partícula , Porosidade , Purificação da Água/instrumentação
17.
Environ Sci Pollut Res Int ; 22(24): 19940-50, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26289339

RESUMO

In this research, the mobilization and distribution of lead originating in roof dust and wet deposition were investigated within a roof dust-rooftop-runoff system. The results indicated that lead from roof dust and wet deposition showed different transport dynamics in runoff system and that this process was significantly influenced by the rainfall intensity. Lead present in the roof dust could be easily washed off into the runoff, and nearly 60 % of the total lead content was present in particulate form. Most of the lead from the roof dust was transported during the late period of rainfall; however, the lead concentration was higher for several minutes at the rainfall beginning. Even though some of the lead from wet deposition, simulated with a standard isotope substance, was adsorbed onto adhered roof dust and/or retained on rooftop in runoff system, most of it (50-82 %) remained as dissolved lead in the runoff for rainfall events of varying intensity. Regarding the distribution of lead in the runoff system, the results indicated that it could be carried in the runoff in dissolved and particulate form, be adsorbed to adhered roof dust, or remain on the rooftop because of adsorption to the roof material. Lead from the different sources showed different distribution patterns that were also related to the rainfall intensity. Higher rainfall intensity resulted in a higher proportion of lead in the runoff and a lower proportion of lead remaining on the rooftop.


Assuntos
Poluentes Atmosféricos/análise , Poeira/análise , Chumbo/análise , Adsorção , Poluentes Atmosféricos/química , Chumbo/química , Chuva/química
18.
Huan Jing Ke Xue ; 36(10): 3715-9, 2015 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-26841603

RESUMO

The ettect of natural organic matter (NOM) and electrolytes on the aggregation of G60 nanoparticles in aquatic systems was studied by using dynamic light scattering. The results showed that the concentration of C60 stable suspension prepared by toluene solvent-exchange method was about 20 mg x L(-1). The C60 nanoparticles in the suspension showed a high zeta potential and particle diameter was around 120 nm. Addition of simple electrolytes induced aggregation of C60 nanoparticles through acompressing electric double layer, which was consistent with the classic Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloidal stability. The critical coagulation concentration (CCC) values of MgCl2 and CaCl2 were 9.6 and 6.7 mmol x L(-1). In presence of humic acid, the addition of NaCl and MgCl2 reduced the attachment efficiency and aggregation rate of C60 and increased CCCs. Humic acid enhanced the stability of C60 in water due to steric repulsion. However, the complexation reaction between Ca2+ and humic acid caused adsorption bridging with C60, which increased the aggregation rate and led to enhanced aggregation. This was identified as the primary mechanism of such enhanced aggregation behaviour. The aggregation and dispersion of C60 in water was influenced by the characteristics of organic matters, electrolyte species and other complex factors.


Assuntos
Eletrólitos/química , Fulerenos/química , Substâncias Húmicas , Nanopartículas/química , Água/química , Adsorção , Cloreto de Cálcio , Cloreto de Magnésio , Cloreto de Sódio , Suspensões
19.
Environ Technol ; 34(9-12): 1429-37, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24191476

RESUMO

Performance of a synthetic-fibre mat was investigated for the treatment of high-turbidity runoff. The impact of different operating parameters, such as hydraulics (flow rate and exchange rate), density current due to temperature and turbidity differences, mat conditions (thickness and number) and particle size were studied. The experimental results showed that increasing the mat thickness and number enhanced turbidity removal. The density current showed significant inverse effect on mat performance. Turbidity removal decreased with the increasing flow rate and exchange rate. Particle size also indicated an influence on removal efficiency. Predictive correlations for turbidity removal efficiency and mat design were established using dimensionless groups based on the experiment. The simulation results indicated that the predicted values correlated with the experimental ones significantly. Finally, the application design process was demonstrated.


Assuntos
Modelos Teóricos , Reologia/métodos , Purificação da Água/instrumentação , Água/química , Nefelometria e Turbidimetria , Tamanho da Partícula , Polietileno/química , Polipropilenos/química
20.
Water Environ Res ; 85(7): 596-603, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23944142

RESUMO

A synthetic-fiber barrier for the removal of turbidity in water was developed and tested using a laboratory scale channel. The effects of hydraulics (flow rate and exchange rate); density current caused by temperature and turbidity difference; barrier conditions (thickness, number and shape); and particle size were analyzed. The experimental results indicated that removal efficiency was positively related to barrier thickness and number, was inversely related to the strength of the density current, and was also negatively affected by the flow rate and exchange rate. A wedged barrier was found to work better than a rectangular one when the same amount of fiber was used. Based on the experimental work, empirical models for the removal efficiency and barrier design were established using dimensionless groups. The modeling results indicated that the predicted values were consistent with the experimental work and the increases and decreases in the performance were suitably simulated.


Assuntos
Modelos Teóricos , Purificação da Água/métodos , Água/análise
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