Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 21
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Environ Monit Assess ; 192(2): 79, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31897735

RESUMO

This study proposed a multi-criteria evaluation system for arable land resources by combining the soil integrated fertility index (IFI) with a soil cleanliness index (based on heavy metals and metalloid content). A total of 16 typical arable land units in Chongming District, China, were evaluated using the proposed evaluation system based on 104 collected soil samples in 16 towns. The comprehensive soil evaluation scores of arable lands in 16 towns were in the range of 90.7 to 99.2 with a mean of 96.2, indicating that the arable land in all 16 towns was at the level of excellent (≥ 90.0). Lower cleanliness indices had a significant impact on the final evaluation score. In comparison with single-index evaluation systems (i.e., the IFI or soil cleanliness index), the proposed multi-criteria system better reflects the quality of the soil. In the practice of arable land requisition and subsidy policy, the proposed multi-criteria evaluation system not only encourages farmers to preserve arable lands during farming but also helps agricultural authorities make effective and reliable management decisions.

2.
Sci Total Environ ; 708: 134833, 2020 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-31796276

RESUMO

The spatial variation of chlorophyll a in the Southern Ocean (SO) was of great significance. Sea surface chlorophyll a concentrations was measured by Ferry Box monitoring system on the Chinese polar research vessel Xue Long, which circumnavigated the Antarctic continent in a clockwise direction during the austral summer 2013-2014 (November 2013-April 2014). The concentrations of chlorophyll a indicated a relatively uniform distribution of 0.049-11.647 mg m-3 (mean 0. 869 mg m-3, n = 152,751). The highest chlorophyll a concentrations (mean 1.847 mg m-3) was found in the Ross sea (RS). In addition, six high-chlorophyll a hot spots were recognized. Analysis revealed that phytoplankton bloom could be controlled by multiple factors in different regions, and the chlorophyll a bloom is attributed to the combined effect of surface and subsurface processes such as, continental shelf, sea ice melting, Circumpolar Deep Water (CDW) upwelling, suitabletemperature, and nutrient injection from subsurface to the surface. The topographic effects, sea ice melting and CDW upwelling may play a major role in controlling primary productivity in the SO. Among of all, CDW upwelling may be the most important role improving primary productivity. This study presented the phytoplankton distribution patterns and the relation with potential growth-controlling factors in the SO, which will provide more insight in the mechanisms that control global warming to reduce global CO2 the atmosphere into the ocean interior.

3.
Environ Pollut ; 253: 1-10, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31301531

RESUMO

Organic pollutants in the Arctic seas have been of concern to many researchers; however, the vast dynamic marine water poses challenges to their comprehensive monitoring within appropriate spatial and temporal scales in the Arctic. In this study, on-board passive sampling of organic pollutants using a self-developed device coupled with triolein-embedded cellulose acetate membranes (TECAMs) was performed during an Arctic cruise. The TECAM extracts were used for target analysis of organophosphorus flame retardants (PFRs), and non-target screening of persistent, bioaccumulative, and toxic (PBT) contaminants using two-dimensional gas chromatography with time-of-flight mass spectrometry (GC × GC-TOFMS). Sixteen chemicals were screened out as PBT contaminants from the 1500 features in the non-target analysis and further identified. Consequently, two chlorinated PFRs (tris(chloroisopropyl)phosphate and tris(1,3-dichloroisopropyl)phosphate) and four PBT contaminants (4-tert-butylphenol, 2-isopropylnaphthalene, 1,1,3-trimethyl-3-phenylindane, and 1-phenylnonan-1-one) were accurately quantified, with the temporally and spatially integrated concentrations ranging from 0.83 ng L-1 to 20.82 ng L-1 in the seawaters. Sources and transport of the contaminants were studied, and ocean current transport (West Spitsbergen Current, WSC) and local sources (human settlement, Arctic oil exploitation, and petroleum fuel emissions) were found to contribute to the presence of the different contaminants. Finally, annual transport fluxes of the contaminants from the North Atlantic to the Arctic Ocean by WSC were estimated, and the results indicate that their hazard to the Arctic should be concerned.


Assuntos
Monitoramento Ambiental/métodos , Retardadores de Chama/análise , Organofosfatos/análise , Água do Mar/química , Poluentes Químicos da Água/análise , Regiões Árticas , Poluentes Ambientais/análise , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Svalbard
5.
Environ Sci Pollut Res Int ; 25(10): 9311-9320, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29249034

RESUMO

We examined per- and polyfluoroalkyl substances (PFASs) in air from eight cities, and in water from six drinking-water treatment plants (DWTPs), in central eastern China. We analyzed raw and treated water samples from the DWTPs for 17 ionic PFASs with high-performance liquid chromatography/negative-electrospray-ionization tandem mass spectrometry (HPLC/(-)ESI-MS/MS), and analyzed the gas and particle phases of atmospheric samples for 12 neutral PFASs by gas chromatography-mass spectrometry (GC-MS). Perfluorooctanoic acid (PFOA) and perfluorohexanoic acid (PFHxA) were the dominant compounds in drinking water, and fluorotelomer alcohols (FTOHs) dominated in atmospheric samples. Of all the compounds in the treated water samples, the concentration of PFOA, at 51.0 ng L-1, was the highest. Conventional treatments such as coagulation (COA), flocculation (FOC), sedimentation (SED), and sand filtration (SAF) did not remove PFASs. Advanced treatments, however, including ultrafiltration (UF) and activated carbon (AC), removed the majority of PFASs except for shorter-chain PFASs such as perfluorobutanoic acid (PFBA) and perfluoropentanoic acid (PFPA). We also investigated human exposure to PFASs via drinking water and the atmosphere and found that the mean daily intake of PFASs was 0.43 ng kg-1 day-1.


Assuntos
Atmosfera/análise , Caproatos/química , Caprilatos/química , Água Potável/química , Fluorcarbonetos/análise , Caproatos/análise , China , Cromatografia Líquida de Alta Pressão , Cidades , Fluorcarbonetos/química , Humanos , Medição de Risco , Espectrometria de Massas em Tandem
6.
Mar Pollut Bull ; 125(1-2): 481-486, 2017 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-28800911

RESUMO

We investigated the distribution of 17 individual per- and polyfluoroalkyl substances (PFASs) in 42 surface water samples collected from the East and South China Seas (7.0-36.0°N, 110.0°N-123.0°E). Concentrations of 7 individual PFASs, including perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), perfluoropentanoic acid (PFPA), perfluorohexanoate (PFHxA), perfluoroheptanoate (PFHpA), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonamide (FOSA), were quantified in the East China Sea, but only concentrations of PFOA and FOSA were quantified in the South China Sea. The total concentrations of the 17 PFASs ranged from 181 to 2658pg/L in the East China Sea and from 62 to 494pg/L in the South China Sea. We also show that river fluxes and ocean currents had a strong influence on the distribution of PFASs in the East China Sea. Using ArcGIS 10.1, we show how ocean currents control the spatial distribution of PFOA in the central South China Sea.


Assuntos
Fluorcarbonetos/análise , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental , Ácidos Graxos/análise , Oceanos e Mares , Rios , Movimentos da Água
7.
Environ Pollut ; 219: 528-536, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27318541

RESUMO

This paper reports the concentrations of polycyclic aromatic hydrocarbons (PAHs) in marine sediments sampled from Prydz Bay, East Antarctica. Total PAH concentrations ranged from 12.95 to 30.93 ng/g, with a mean of 17.99 ± 5.57 ng/g. Two- and three-ring PAHs were the most abundant compounds found at the majority of the sampling stations of Prydz Bay. Long-range atmospheric transportation was found to play an important role in determining the spatial distribution of PAHs in the sediments sampled here. However, transport by ocean currents and release from melting glaciers were also found to influence PAH distributions in the sediments of East Antarctica. The vertical migration of PAHs in sediments showed a decreasing trend with depth, with higher concentrations in the relatively shallow-water regions (<500 m) found on the Fram and Four Ladies banks compared with those of the intermediate-depth (500-1000 m) and deep-water regions (>1000 m) of the Amery Basin and associated Canyons, respectively. A Pearson correlation analysis between PAH concentrations and sediment parameters demonstrated that PAHs has poor correlations with grain size, but has positive correlation with total organic carbon, indicated complex processing during transfer to remote environments. The results of qualitative and quantitative analyses indicate that the PAHs sampled here were derived mainly from a mixture of biomass combustion, traffic emissions, and petrogenic sources.


Assuntos
Baías/química , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , Regiões Antárticas , Camada de Gelo/química
8.
PLoS One ; 10(3): e0119144, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25793925

RESUMO

To evaluate risk via inhalation exposure of polybrominated diphenyl ethers (PBDEs) in office environment, thirty-six pairs air samples including PM2.5 (particles with aerodynamic diameter less than 2.5 µm), PM10 (particles with aerodynamic diameter less than 10 µm), total suspended particles (TSP) with matching gas phase were collected in office environment in Shanghai, China. The average concentrations of PM2.5, PM10 and TSP were 20.4, 27.2 and 50.3 µg/m3, respectively. Σ15PBDEs mean concentrations in PM2.5, PM10, TSP and gas phase were 51.8, 110.7, 148 and 59.6 pg/m3, respectively. Much more PBDEs distributed in fine fractions than coarse ones. PBDEs congener profiles found in PM2.5, PM10 and TSP (dominated by BDE-209) were different from that in gas phase (dominated by the tri- to penta-BDEs). Approximately 3.20 pg/kg/d PM2.5 bound PBDEs can be inhaled into the lung; 3.62 pg/kg/d PM10-PM2.5(particles with aerodynamic diameter of 2.5-10 µm) bound PBDEs tended to be deposited in the upper part of respiratory system, and the intake of PBDEs via gas-phase was 2.74 pg/kg/d. The exposure of PBDEs was far below the minimal risk levels (MRLs), indicating lower risk from PBDEs via inhalation in the studied office in Shanghai.


Assuntos
Poluentes Atmosféricos/química , Poluição do Ar em Ambientes Fechados , Éteres Difenil Halogenados/química , Material Particulado/química , China , Exposição Ambiental , Monitoramento Ambiental , Medição de Risco
9.
Environ Pollut ; 198: 25-31, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25549864

RESUMO

This study evaluated the levels and spatial distribution of PBDEs in 9 typical offices in Shanghai, China through the sample analysis of air and settled dust (floor dust, desktop dust and dust in computer case). PBDEs in air ranged from 93 to 322 pg/m(3), while the PBDEs levels in dust varied from 247 to 3.3 × 10(4) ng/g. Spatial variability of PBDEs in office dust was evident and likely influenced by air exchange and the use of electronic devices. A significant positive linear correlation was observed between the power usage rate and PBDE levels in both office air (R(2) = 0.81) and settled dust (R(2) = 0.94). The PBDEs exposure via inhalation and dust ingestion were both analyzed to estimate the life-time cancer risk, which is 1.34 × 10(-22) to 7.16 × 10(-22), significantly lower than the threshold level (10(-6)). Non-cancer risk indicated by the hazard index (<1) is also low in current exposure conditions.


Assuntos
Poluição do Ar em Ambientes Fechados/análise , Monitoramento Ambiental , Éteres Difenil Halogenados/análise , Exposição Ocupacional/estatística & dados numéricos , Local de Trabalho , Ar/análise , Poluição do Ar em Ambientes Fechados/estatística & dados numéricos , China , Poeira/análise , Humanos
10.
Environ Sci Pollut Res Int ; 22(11): 8603-10, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25563828

RESUMO

The total mercury (THg) and methylmercury (MeHg) distributions in the surface sediments of Kongsfjorden, Svalbard, in the Norwegian Arctic were investigated in this study. The results showed that THg concentrations ranged from 9.11 to 86.73 ng g(-1), whereas MeHg concentrations had an average of only 0.11 ng g(-1). Factors that control the distribution and methylated transformation of mercury were examined, and the results suggested that the movements of ocean currents and glaciers affect the THg distribution. The total organic carbon (TOC) and N contents in the sediments were positively correlated with THg concentration, which indicated that the THg distribution at these stations was primarily controlled by organic matter in the sediments. A complex relationship was observed between the THg and S contents, possibly due to anthropogenic activities involved in the perennial scientific expedition. MeHg and THg exhibited similar correlations with the sediment chemical characteristics for all stations suggesting that MeHg may be produced locally through the microbial methylation of mercury.


Assuntos
Monitoramento Ambiental/estatística & dados numéricos , Sedimentos Geológicos/química , Mercúrio/análise , Compostos de Metilmercúrio/análise , Carbono/análise , Cromatografia Gasosa , Monitoramento Ambiental/métodos , Nitrogênio/análise , Svalbard
11.
Chemosphere ; 119: 820-827, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25218980

RESUMO

Spatial distributions of perfluoroalkyl substances (PFASs) were investigated in surface waters in Shanghai, Jiangsu and Zhejiang Provinces of eastern China during 2011. A total of 39 samples of surface waters, including 29 rivers, 6 lakes and 4 reservoirs were collected. High performance liquid chromatography/negative electrospray ionization-tandem mass spectrometry (HPLC/(-)ESI-MS/MS) was used to identify and quantify PFASs. Concentrations of PFAS were greater in Shanghai than that in Zhejiang Province. Concentrations of the sum of PFASs (∑PFASs) in Shanghai and Kunshan ranged from 39 to 212 ng L(-1), while in Zhejiang Province, concentrations of ∑PFASs ranged from 0.68 to 146 ng L(-1). Perfluorooctanoic acid (PFOA) was the prevalent PFAS in Shanghai. In contrast, PFOA and perfluorohexanoic acid (PFHxA) were the prevalent PFASs in Zhejiang Province. Concentrations of perfluorooctane sulfonate (PFOS) ranged from <0.07 to 9.7 ng L(-1). Annual mass of ∑PFASs transported by rivers that flow into the East China Sea were calculated to be more than 4000 kg PFASs. Correlation analyses between concentrations of individual PFASs showed the correlation between PFHxA and PFOA was positive, while the correlation between PFHxA and perfluorooctane sulfonamide (FOSA) was negative in Shanghai, which indicated that PFHxA and PFOA have common sources. Principal component analysis (PCA) was employed to identify important components or factors that explain different compounds, and results showed that PFHxA and FOSA dominated factor loadings.


Assuntos
Monitoramento Ambiental , Fluorcarbonetos/análise , Lagos/química , Rios/química , Poluentes Químicos da Água/análise , China , Cromatografia Líquida de Alta Pressão , Estações do Ano , Espectrometria de Massas em Tandem
12.
Bioresour Technol ; 143: 10-7, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23774291

RESUMO

In this study, the biofilms formed in a vermifilter (VF) with earthworms and a conventional biofilter (BF) without earthworms were compared to investigate the effects of earthworms on the characteristics of biofilms during an excess sludge treatment period of 4months. Typical macrographs and micrographs of the biofilms showed that the feeding and casting actions of earthworms remarkably modified the VF morphology. Elemental analysis and fluorescence spectra indicated that earthworms enhanced the stabilization of organic matter by accelerating the mineralization and humification of organic materials during vermiconversion. In addition, bacterial communities inhabiting the VF biofilm showed that earthworms increased both bacterial diversity and metabolic activities in the film, as revealed by automatic testing bacteriology (ATB) expression and sequencing data. These results demonstrate that earthworms influence the structure and biochemical characteristics of biofilms and enhance their bacterial diversity and functions for improved sludge stabilization.


Assuntos
Biodegradação Ambiental , Biofilmes , Filtração/métodos , Oligoquetos/metabolismo , Esgotos , Animais , Bactérias/genética , Bactérias/isolamento & purificação , Sequência de Bases , Primers do DNA , Microbiologia do Solo , Espectrometria de Fluorescência
14.
Environ Geochem Health ; 35(2): 257-69, 2013 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22965895

RESUMO

Trace metal contents (Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb and Zn) have been measured in 27 surface sediment samples collected from Kongsfjorden, Svalbard, Norwegian Arctic. The analyses yielded concentration values (in mg kg(-1)) of 0.13-0.63 for Cd, 11.89-21.90 for Co, 48.65-81.84 for Cr, 21.26-36.60 for Cu, 299.59-683.48 for Mn, 22.43-35.39 for Ni, 10.68-36.59 for Pb, 50.28-199.07 for Zn and 8.09-65.34 for Hg (in ng g(-1)), respectively. Relative cumulative frequency method has been used to define the baseline values of these metals, which (in mg kg(-1)) were 0.14 for Cd, 13.56 for Co, 57.86 for Cr, 25.14 for Cu, 364.08 for Mn, 26.22 for Ni, 17.46 for Pb, 70.49 for Zn and 9.76 for Hg (in ng g(-1)), respectively. The enrichment factor analysis indicated that Hg showed some extent of anthropogenic pollution, while Pb, Zn and Cd showed limited anthropogenic contamination in the study areas.


Assuntos
Poluentes Ambientais/análise , Sedimentos Geológicos/química , Metais Pesados/análise , Regiões Árticas , Monitoramento Ambiental , Poluentes Ambientais/química , Metais Pesados/química , Noruega
15.
Bioresour Technol ; 117: 214-21, 2012 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22613898

RESUMO

Previous studies have shown that the stabilization of excess sludge by vermifiltration can be improved significantly through the use of earthworms. To investigate the effect of earthworms on enhancing sludge stabilization during the vermifiltration process, a vermifilter (VF) with earthworms and a conventional biofilter (BF) without earthworms were compared. The sludge reduction capability of the VF was ∼85% higher than that of the BF. Specifically, elemental analysis indicated that earthworms enhanced the stabilization of organic matter. Furthermore, earthworm predation strongly regulated microbial biomass while improving microbial activity. Denaturing gradient gel electrophoresis (DGGE) analysis showed that the most abundant microbes in the VF biofilms and earthworm casts were Flavobacterium, Myroides, Sphingobacterium, and Myxococcales, all of which are known to be highly effective at degrading organic matter. These results indicate that earthworms can improve the stabilization of excess sludge during vermifiltration, and reveal the processes by which this is achieved.


Assuntos
Filtração/instrumentação , Oligoquetos/metabolismo , Esgotos/microbiologia , Purificação da Água/instrumentação , Purificação da Água/métodos , Animais , Sequência de Bases , Biodegradação Ambiental , Biofilmes , Análise por Conglomerados , Eletroforese em Gel de Gradiente Desnaturante , Elementos , Dados de Sequência Molecular , Oxirredutases/metabolismo , Filogenia , RNA Ribossômico 16S/genética
16.
J Hazard Mater ; 209-210: 335-42, 2012 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-22305203

RESUMO

The multi-matrices samples from snow (n=4), lake water (n=4), surface runoff water (SRW) (n=1) and coastal seawater (n=10) were collected to investigate the spatial distribution and the composition profiles of per- and polyfluoroalkyl substances (PFASs) in Fildes Peninsula, King George Island, Antarctica in 2011. All samples were prepared by solid-phase extraction and analyzed by using high performance liquid chromatography/negative electrospray ionization-tandem mass spectrometry (HPLC/(-)ESI-MS/MS). 14 PFASs in snow, 12 PFASs in lake water, 9 PFASs in SRW and 13 PFASs in coastal seawater were quantified, including C(4), C(7), C(8), C(10) PFSAs, C(4)-C(9), C(11)-C(14), C(16) PFCAs, and FOSA. PFOA was detected in all samples with the highest concentration (15,096 pg/L) in coastal seawater indicating a possible influence of local sewage effluent. High concentration and mostly frequency of PFBA occurred in snow (up to 1112 pg/L), lake water (up to 2670 pg/L) and SRW (1431 pg/L) while detected in the range of method detection limited (MDL) in the coastal seawaters indicate that PFBA is mainly originated from atmospheric dust contamination and also affected by the degradation of their precursors. No geographical differences in PFOS concentrations (n=8, 18 ± 3 pg/L) were measured in all snow and lake water samples also suggests that PFOS could be originated from the degradation of their precursors which can transported by long-range atmospheric route, but in a very low level.


Assuntos
Fluorcarbonetos/análise , Poluentes Químicos da Água/análise , Regiões Antárticas , Cromatografia Líquida de Alta Pressão , Espectrometria de Massas por Ionização por Electrospray
17.
Environ Monit Assess ; 184(11): 7013-21, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22160386

RESUMO

Metal contents (Al, Ca, Cd, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, Ti, and Zn) have been measured in 30 surface soils on Fildes Peninsula, King George Island, Antarctica, yielding values (in milligrams kilogram(-1)) of 41.57-80.65 (Zn), 2.76-60.52 (Pb), 0.04-0.34 (Cd), 7.18-25.03 (Ni), 43,255-70,534 (Fe), 449-1,401 (Mn), 17.10-64.90 (Cr), 1,440-25,684 (Mg), 10,941-49,354 (Ca), 51.10-176.50 (Cu), 4,388-12,707 (Ti), 28,038-83,849 (Al), and for Hg (in nanograms gram(-1)) 0.01-0.06. Relative cumulative frequency analysis was used to determine the baseline values for the 13 metals. Compared with adjacent areas in Antarctica, Mg and Ni are significantly lower, but Cu is significantly higher than that of McMurdo Station. Enrichment factor analysis and the geo-accumulation index method were applied in order to determine the extent of anthropogenic contamination, and both show that Pb, Cd, and Hg have been significantly increased by human activities. Principal component analysis was used to identify the sources of metals in these soil samples.


Assuntos
Monitoramento Ambiental , Metais/análise , Poluentes do Solo/análise , Solo/química , Regiões Antárticas , Coleta de Dados , Poluição Ambiental/estatística & dados numéricos , Humanos , Metais/normas , Poluentes do Solo/normas
18.
Bioresour Technol ; 101(1): 98-104, 2010 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-19729302

RESUMO

Laboratory experiments were conducted in a continuous plug-flow anaerobic/aerobic (A/O) process to kinetically investigate the long-term effect of the different carbon sources (i.e., acetate, acetate/propionate, propionate and glucose) on the competition between polyphosphorus accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs). It was found that propionate was more benefit than acetate for PAOs even in the A/O process, and PAOs enriched with acetate were readily able to metabolize propionate without the requirement of adaptation. Glucose gave GAOs metabolic advantage in the PAOs-GAOs competition, which thereby worsened the EBPR performance. Nevertheless, the EBPR capacity could recover by returning carbon to acetate, with the acclimation time of approximately 2-SRTs. This suggests that the varying of carbon can be an effective approach to provide PAOs a competitive advantage over GAOs. Additionally, MLVSS/MLSS could indicate the shift of the microorganism between GAOs and PAOs, but it was not as precise as the biomass-P content.


Assuntos
Bactérias Aeróbias/metabolismo , Bactérias Anaeróbias/metabolismo , Carbono/metabolismo , Glicogênio/metabolismo , Fósforo/metabolismo , Poluentes Químicos da Água/metabolismo , Purificação da Água/métodos , Biodegradação Ambiental , Reatores Biológicos/microbiologia
19.
J Hazard Mater ; 168(1): 331-7, 2009 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-19286316

RESUMO

A mixture of converter slag and coal cinder as adsorbent for the removal of phosphorous and other pollutants was studied in the paper. The maximum P adsorption capacity, pH of solution, contact time and initial phosphate concentration were evaluated in batch experiments for the two materials firstly. The data of P sorption were best fitted to Langumir equation, and the maximum adsorption capacities of converter slag and coal cinder were 2.417 and 0.398 mg P/g, respectively. The pH of solutions with converter slag and coal cinder changed dramatically with time and closed to 8 in 8h, and the influence of initial pH on phosphate removal by coal cinder was more significant than by converter slag. Phosphate removal rate by converter slag decreased with increase of initial phosphate concentrations. Subsequently, two flow-through columns (Column 1#, V(converter slag):V(coal cinder)=1:5; Column 2#, V(converter slag):V(coal cinder)=1:3) were operated for the removal of phosphorous and other pollutants from the effluents of a vermifilter for nearly eleven months. Results indicated the average removal efficiency of total phosphorus, dissolved phosphorus, COD and NH(4)(+)-N by Column 1# were 44%, 56%, 31% and 67%, and by Column 2# were 42%, 54%, 24% and 57%, respectively. Column 1# had higher removal efficiency for P and other pollutants.


Assuntos
Carvão Mineral , Fósforo/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Concentração de Íons de Hidrogênio , Resíduos Industriais , Cinética , Purificação da Água/métodos
20.
Circ Res ; 103(3): 269-78, 2008 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-18599872

RESUMO

p90 ribosomal S6 kinase (p90RSK) is activated in cardiomyopathies caused by conditions such as ischemia/reperfusion injury and diabetes mellitus in which prolongation of cardiac repolarization and frequent arrhythmias are common. Molecular mechanisms underlying the electric remodeling in cardiac diseases are largely unknown. In the present study, we determined the role of p90RSK activation in the modulation of voltage-gated K+ channel activity determining cardiac repolarization. Mice with increased cardiac p90RSK activity due to transgenic expression of p90RSK (p90RSK-Tg) had prolongation of QT intervals and of ventricular myocyte action potential durations. Fast transient outward K+ current (I(to,f)), slow delayed outward K+ current (I(K,slow)), and steady-state K+ current (I(SS)) were significantly decreased in p90RSK-Tg mouse ventricular myocytes. mRNA levels of Kv4.3, Kv4.2, Kv1.5, Kv2.1, and KChIP2 from ventricles between p90RSK-Tg and nontransgenic littermate control mice were similar, as assessed by quantitative reverse transcriptase-polymerase chain reaction, indicating that p90RSK regulates voltage-gated K+ channels through posttranslational modification. Kv4.3- and Kv1.5- rather than Kv4.2- and Kv2.1-encoded channels in HEK 293 cells were inhibited by p90RSK. In vitro phosphorylation analysis showed that Kv4.3 was phosphorylated by p90RSK at 2 conserved sites, Ser516 and Ser550. p90RSK expression significantly inhibited Kv4.3- and Kv4.3 and KChIP2-encoded channel activities in HEK 293 cells, whereas p90RSK's effects were blocked by amino acid mutation(s) at phosphorylation site(s) in Kv4.3. Hydrogen peroxide, a mediator of induced cardiac p90RSK activation in ischemia/reperfusion injury and diabetes mellitus, had effects similar to those of p90RSK on Kv4.3- or Kv4.3- and KChIP2-encoded channels. Fluoromethylketone, a specific p90RSK inhibitor, abolished hydrogen peroxide effects. These findings indicate that p90RSK activation is critical for reactive oxygen species-mediated inhibition of voltage-gated K+ channel activity and leads to prolongation of cardiac repolarization.


Assuntos
Coração/fisiologia , Canais de Potássio de Abertura Dependente da Tensão da Membrana/metabolismo , Espécies Reativas de Oxigênio/farmacologia , Proteínas Quinases S6 Ribossômicas 90-kDa/fisiologia , Potenciais de Ação , Animais , Ativação Enzimática/efeitos dos fármacos , Ventrículos do Coração/citologia , Peróxido de Hidrogênio/farmacologia , Síndrome do QT Longo , Potenciais da Membrana , Camundongos , Camundongos Transgênicos , Miócitos Cardíacos/fisiologia , Canais de Potássio de Abertura Dependente da Tensão da Membrana/antagonistas & inibidores , Proteínas Quinases S6 Ribossômicas 90-kDa/metabolismo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA