Biomedical subjects

Shu Tao

Publications and source records attributed to Shu Tao.

At least 19 recordsLinked to original sources

PubMed2007

Simulating the temporal changes of OCP pollution in Hangzhou, China.

A dynamic fugacity model was applied to simulate the changes of contents and transfer fluxes of hexachlorocyclohexane (HCHs) and dichloro-diphenyl-trichloroethane (DDTs) from 1950s in the environment of Hangzhou, China. The receptors are composed of air, surface water, soils, sediment and biota compartments. The model provides a method to combine loadings of HCHs and DDTs from various sources with a series of physical-chemical processes to estimate concentrations and transport fluxes of HCHs and DDTs. Model results suggested that the calculated concentrations were in line with the observed ones. The highest contents of HCH and DDT in the environment of study area were 523 t and 471 t before 1983, among which about 80.7% HCHs and 93.2% DDTs remained in the soil compartment. From 1984 to now, contents of HCHs and DDTs had decreased to about 0.07% and 0.40% of their highest amount (before 1983), and only about 0.001% and 0.014% will expect to be left in 2020 in the study area according to the model prediction. Before 1983, the main transfer fluxes of HCHs were deposition from air to soil, runoff from soil to water and diffusion from soil to air, but for DDTs the main transfer fluxes were deposition from air to soil and water, and transfer from water to sediment. From 1984 to now, runoff from soil to water and transfer from water to sediment became the dominant processes. Although a large amount of HCHs and DDTs had been applied to the study area, their residue levels in the soils were much lower than those in North China (had lesser HCHs and DDTs application than in South China) at present time, and close to other locations of South China (had similar HCHs and DDTs application level). It can be attributed to the high precipitation and temperature that enhances the processes of wet deposition, evaporation and degradation of OCPs. Sensitivities of the input parameters to the calculated concentrations were evaluated using coefficient-of-variation normalized sensitivity coefficients. The model was also subjected to uncertainty analyses using a Monte Carlo simulation.

Air Pollutants↗

PubMed2006

Sorption of organic contaminants by biopolymers: role of polarity, structure and domain spatial arrangement.

Sorption behavior of hydrophobic organic contaminants (HOCs) (i.e., pyrene, phenanthrene and naphthalene) by native and chemically modified biopolymers (lignin, chitin and cellulose) was examined. Lignins (native and treated) showed nonlinear sorption for all compounds studied, emphasizing their glassy character. Chitins and celluloses had linear isotherms for phenanthrene and naphthalene, illustrating the dominance of partitioning, while pyrene yielded nonlinear isotherms. Sorption capacity (K(oc)) of HOCs was negatively correlated with the polarity [(O+N)/C] of the biopolymers. Aromatic and alkyl+aromatic C percentages, rather than alkyl C content, demonstrated a better correlation with K(oc) values, indicating the importance of aromatic structures for HOC affinity. Hydrophobicity (K(ow))-normalized K(oc) values decreased sharply with increasing percentage of O-alkyl C versus total aliphatic C (O-alkyl C/total aliphatic C) or with polar C/(alkyl+aromatic C) ratio of the biopolymers until their values reached 80% and 4, respectively, illustrating the effect of surrounding polar groups on reducing affinity for HOCs. Overall, the results of this study highlight the role of spatial arrangement of domains within biopolymers in sorption of HOCs, and point to sorbent properties, such as functionality, polarity and structure, jointly regulating the sorption of HOCs in biopolymers.

Adsorption↗

PubMed2006

Characterization of TSP-bound n-alkanes and polycyclic aromatic hydrocarbons at rural and urban sites of Tianjin, China.

Total suspended particle (TSP) was collected and analyzed at rural and urban sites in Tianjin, China during the domestic heating season (from 15 November to 15 March) of 2003/4 for n-alkanes and 16 polycyclic aromatic hydrocarbons (PAHs). The normalized distribution of n-alkanes with the peak at C22, C23, C24 or C25 suggested that fossil fuel utilization was the major source of particulate n-alkanes at both sites. PAHs normalized distribution for each sample was similar and the higher molecular weight PAH dominated the profile (around 90%) indicating a stronger combustion source at both sites. Precipitation and wind were the most important meteorological factors influencing TSP and PAHs atmospheric concentrations. In the urban area the emission height had significant influence on PAHs levels at different heights under the relative stable atmospheric conditions. Coal combustion was the major source for TSP-bound PAHs at both sites based on some diagnostic ratios.

Air Pollutants↗

PubMed2006

A method for determining pyrene in mucus using synchronous fluorimetry with multiple standard additions.

A new method was proposed to determine pyrene in mucus, which combined the synchronous fluorimetry with the multiple standard addition method (SFMSA). The method was used to determine pyrene in mucus directly without pretreatment. The method detection limit (MDL) for pyrene in mucus was measured as 0.47 ng/ml with a relative standard deviation of 12.7% (n = 7). The standard addition graph was linear in the range 0.05-50.00 ng/ml (r(2) = 0.9989). SFMSA was validated using a GC/MS method as a reference method, and nice agreement was found. The pyrene in mucus can be directly monitored by SFMSA without solvent extraction of samples. This indicates that SFMSA is more timesaving, less laborious and cheaper than the GC/MS method with solvent extraction. SFMSA has lower MDL and higher average recovery than the GC/MS method.

Animals↗

PubMed2006

Residual concentrations of micropollutants in benthic mussels in the coastal areas of Bohai Sea, North China.

Studies of heavy metals and organic pollutants in different benthic mussel species from Bohai Sea show that concentrations of Cd in mussels commonly exceed national biological quality standards. In addition, a site located in Laizhou Bay exhibits higher average concentrations of As, Hg and Pb with respect to the other sites. Residual levels of petroleum hydrocarbons at several sites in Liaodong Bay also exceed quality guidelines. Contents and compositional characteristics of DDT and its metabolites in mussels suggest the probability of recent inputs and potential ecological risks to the local benthic environment.

Animals↗

PubMed2006

Dispersion modeling of polycyclic aromatic hydrocarbons from combustion of biomass and fossil fuels and production of coke in Tianjin, China.

A USEPA, procedure, ISCLT3 (Industrial Source Complex Long-Term), was applied to model the spatial distribution of polycyclic aromatic hydrocarbons (PAHs) emitted from various sources including coal, petroleum, natural gas, and biomass into the atmosphere of Tianjin, China. Benzo[a]pyrene equivalent concentrations (BaPeq) were calculated for risk assessment. Model results were provisionally validated for concentrations and profiles based on the observed data at two monitoring stations. The dominant emission sources in the area were domestic coal combustion, coke production, and biomass burning. Mainly because of the difference in the emission heights, the contributions of various sources to the average concentrations at receptors differ from proportions emitted. The shares of domestic coal increased from approximately 43% at the sources to 56% at the receptors, while the contributions of coking industry decreased from approximately 23% at the sources to 7% at the receptors. The spatial distributions of gaseous and particulate PAHs were similar, with higher concentrations occurring within urban districts because of domestic coal combustion. With relatively smaller contributions, the other minor sources had limited influences on the overall spatial distribution. The calculated average BaPeq value in air was 2.54 +/- 2.87 ng/m3 on an annual basis. Although only 2.3% of the area in Tianjin exceeded the national standard of 10 ng/m3, 41% of the entire population lives within this area.

Air Movements↗

PubMed2006

A chemical extraction method for mimicking bioavailability of polycyclic aromatic hydrocarbons to wheat grown in soils containing various amounts of organic matter.

In this study, we have evaluated the extent to which organic matter contents in soils influence the accumulation of PAHs by the roots of wheat plants and have developed a rapid chemical method for determining the bioavailability of PAH. Four polycyclic aromatic hydrocarbons (PAHs), naphthalene, acenaphthylene, fluorene, and phenanthrene, were added to natural soil samples with different amounts of organic matterfor pot experiments to evaluate apparent bioavailability of PAHs to wheat roots (Triticum aestivum L.). The extractabilities of PAHs in the soil were tested by a sequential extraction scheme using accelerated solvent extraction with water, n-hexane, and a mixture of dichloromethane and acetone as solvents. The water or n-hexane-extractable PAHs were positively correlated to dissolved organic matter (DOM) and negatively correlated to total organic matter (TOM), indicating mobilization and immobilization effects of DOM and TOM on soil PAHs, respectively. The apparent accumulation of PAHs by wheat roots was also positively and negatively correlated to DOM and TOM, respectively. As a result, there are positive correlations between the amounts of PAHs extracted by water or n-hexane and the quantities accumulated in plant roots, suggesting the feasibility of using water- or n-hexanes-extractable fractions as indicators of PAH availability to plants.

Biological Availability↗

PubMed2006

Organochlorine pesticides in soil profiles from Tianjin, China.

Soil cores were collected from soils at five sites in Tianjin area for the determination of hexachlorocyclohexane isomers (HCHs, including alpha-HCH, beta-HCH, gamma-HCH and delta-HCH), dichlorodiphenyltrichloroethane and metabolites (DDXs, including p,p'-DDT, p,p'-DDE and p,p'-DDD) and total organic carbon (TOC). The levels and vertical distributions of HCHs and DDXs are studied. Results show that the application of pesticides in the past years was the major contributor of HCHs and DDXs accumulation in the sampling areas. Significant positive correlations were seen between the residual and application amounts of HCHs and DDXs. Wastewater irrigation did not bring a significant contribution of HCHs or DDXs into the soils. HCHs and DDXs concentrations peak at the surface and decline in soil profile with depth, while fluctuations were observed in the plow layers of some cultivated soils caused by frequent cultivation activities and batch irrigation. Positive correlations were observed between the contents of TOC and HCHs and DDTs. Although the amounts of HCHs application in all sampling sites are larger than DDXs, at surface and near surface layers of most sampling sites, the concentrations of summation operatorHCHs are lower than summation operatorDDXs. The composition of DDXs in the applied pesticides and sampled soils indicates that there is no recent DDT input at the sample areas.

China↗

PubMed2006

Emission of polycyclic aromatic hydrocarbons in China.

Emission of 16 polycyclic aromatic hydrocarbons (PAHs) listed as U.S. Environmental Protection Agency (U.S. EPA) priority pollutants from major sources in China were compiled. Geographical distribution and temporal change of the PAH emission, as well as emission profiles, are discussed. It was estimated that the total PAH emission in China was 25,300 tons in 2003. The emission profile featured a relatively higher portion of high molecular weight (HMW) species with carcinogenic potential due to large contributions of domestic coal and coking industry. Among various sources, biomass burning, domestic coal combustion, and coking industry contributed 60%, 20%, and 16% of the total emission, respectively. Total emission, emission density, emission intensity, and emission per capita showed geographical variations. In general, the southeastern provinces were characterized by higher emission density, while those in western and northern China featured higher emission intensity and population-normalized emission. Although energy consumption in China went up continuously during the past two decades, annual emission of PAHs fluctuated depending on the amount of domestic coal consumption, coke production, and the efficiency of energy utilization.

Air Pollutants↗

PubMed2006

Restoration of marine coastal ecosystem health as a new goal for integrated catchment management in Tolo Harbor, Hong Kong, China.

This article demonstrates why it is necessary to have the restoration of marine coastal ecosystem health as a new goal for integrated catchment management in the coastal area of Tolo Harbor. The present goal of integrated catchment management (ICM) in the Tolo Harbor is based on water quality objectives. The performance of the ICM plan, the Tolo Harbor Action Plan (THAP), was evaluated using marine coastal ecosystem health indicators including both stress and response indicators. Since the implementation of THAP in 1988, some significant reductions in pollution loading have been observed: reduction of 83% of biological oxygen demand load and 82% of total nitrogen between 1988 and 1999. There has also been an improvement in the health of Tolo Harbor's marine coastal ecosystem as evidenced by trends in physical, chemical, and biological indicators, although reverse fluctuations in some periods exist. However, such improvement can only be considered as the first sign of complete ecosystem health restoration, because ecosystem health covers not only physical, chemical, and biological aspects of an ecosystem, but also ecosystem service functions. The findings support the need to take the restoration and protection of marine coastal ecosystem health as a new goal rather than using water quality objectives. Steps necessary to further improve Tolo Harbor's marine coastal ecosystem health are also discussed.

Animal Husbandry↗

PubMed2006

Two-compartment sorption of phenanthrene on eight soils with various organic carbon contents.

Sorption characteristics of phenanthrene (PHE) were studied on eight soils with organic carbon contents spanning over an order of magnitude using phase distribution relationships (PDRs) at 1 h, 48 h, and 720 h contact times. A new algebraic method was employed to describe the sorption characteristics at different time intervals (between 1 h and 48 h, and 1 h and 720 h). It was found that nonlinearity increased with increasing contact time and sorption that occurred in the subsequent time interval following the initial 1 h exhibited stronger isotherm nonlinearity. Sorption coefficients were positively correlated with the organic carbon contents of the soils. Detailed sorption dynamics were also examined on these soils. A two-compartment, first-order model was used to describe the sorption dynamics. The rate constants of the two compartments differed 18-170 times, suggesting the dissimilar sorption behaviors of the mathematically separated compartments. These two compartments were labeled fast and slow sorption compartment according to the rate constants. Calculation showed that the fast compartment accounted for over 80% of the overall sorption at the initial 1 h, while the slow compartment predominated the total sorption in the following 47 h. By combining the discussion of PDRs and sorption dynamics, the contributions of the two compartments to linear and nonlinear sorption were differentiated. The slow sorption compartment made a major contribution to nonlinear sorption and possibly to sequestration of organic pollutants by these soils.

Adsorption↗

PubMed2006

An approach to assess ecological risk for polycyclic aromatic hydrocarbons (PAHs) in surface water from Tianjin.

Three approaches were applied and compared to evaluate additive toxic effects of eight PAHs to aquatic organisms in rivers in the Tianjin area. Although the toxicity of the studied PAH compounds did not significantly increase the risk to aquatic organisms, the results of all three approaches indicated that the additive effect of the eight PAHs was significantly stronger than any individual compound acting alone, which indicated the applicability of the approaches. Further, of the compounds studied, anthracene was the major contributor to the overall toxic effect of the mixture. The calculated geometric means of the hazard quotient for the additive effect varied from 0.00055 to 0.00062, compared to the hazard quotient of individual PAHs which ranged from 5.1 x 10-6 to 0.00053. The hazard quotient distribution geometric mean was 0.00058, with 95% of the quotient between 6.6 x 10-5 and 0.051. Overlapping areas varied from 0.00015 to 0.02 for individual PAHs and was 0.03 for additive toxicity.

Animals↗

PubMed2006

[Effect of surfactants on biodegradation of PAHs by white-rot fungi].

The impacts of surfactants (Tween80, Trition X-100, LAS and SDS) on PAHs degradation by white-rot fungi in aqueous system and soil-water system were studied. Results show that the type and concentration of surfactants, PAHs statues, pH value of the systems and temperature have impacts on the degradation of PAHs. In aqueous system, all the four surfactants restrained the degradation of PAHs. In soil-water system, Trition X-100 and SDS restrained the degradation of PAHs, while the impacts of Tween80 and LAS on PAHs degradation were influenced by the concentration of the surfactants. Low concentration Tween80 and LAS didn't promote the degradation of PAHs, and even played minor effects of restrain. But the degradation of PAHs could be enhanced with the increasing of the concentrations of Tween80 and LAS to certain levels. However, Tween80 and LAS with significant higher concentrations didn't show higher abilities on the promotion of PAHs degradation.

Biodegradation, Environmental↗

PubMed2006

[Exposure of traffic police in Haidian district to PAHs].

Personal samplers were used for measurement of exposure of traffic policeman in Beijing in summer 2004. The total exposed concentrations were (1,520 +/- 759) ng/m3 and (148 +/- 118) ng/m3 for gaseous and particle phases PAHs, which were significantly higher than those measured at control site away from the street. The total exposed concentration of carcinogenic PAHs were (14.9 +/- 5.9) ng/m3 for policeman and (6.7 +/- 3.6) ng/m3 for control, which were primarily contributed by particle phase PAHs. The daily variation of the exposure was under influences of temperature and humidity. Positive correlation between gaseous PAHs and humidity and negative correlations between both gaseous and particle PAHs and temperature were revealed.

Air Pollutants↗

PubMed2006

[Desorption of polycyclic aromatic hydrocarbons from soil in presence of surfactants].

Four types of surfactant were used to study their effects on polycyclic aromatic hydrocarbons (PAHs) desorption from artificially contaminated and oil-contaminated soil. The results show that the desoption of PAHs from soil is affected by the type and concentration of surfactant and also by the character and state of PAHs. Surfactants don't improve PAHs desorption from soil when their concentrations are below or near their critical micelle concentration (CMC) values. While, surfactants could obviously enhance the desorption process when the concentrations exceeded the CMC values. The desorption ratios of PAHs were increasing with the increase of surfactant concentrations. Comparatively, lower hydrophile lipophile balance(HLB) can lead to more obvious surfactant solubilization. There were linear relationship between PAHs desorption ratio and PAHs lgKow value. The desorption ratio of PAHs in artificially contaminated soil was higher than in oil-contaminated soil.

Adsorption↗

PubMed2006

[Distribution behaviors of phenanthrene to humic fractions in natural soil].

After adsorption of phenanthrene by the natural soil under different concentrations initially added, the soil sample was extracted for humic acid fraction (including humic acid and fulvic acid), and the sorption amount of phenanthrene in humin fraction was calculated to investigate the adsorption/distribution kinetics in two soil organic fractions and the corresponding influence of original phenanthrene concentration. The experimental data were fitted using Freundlich equation. The results show that, distribution of phenanthrene in the soil exhibited a multi-stage property, i.e., from a first fast sorption to a breakthrough at about 48 h, then followed by a slow sorption procedure. In the fast sorption stage (before 48 h), there was an up-to-down fluctuation of phenanthrene sorption ratio (sorption amount/added amount) in humic acid fraction, possibly due to surface sorption by minerals and competitive sorption by humin fraction. In the slow sorption stage, variations in sorption ratio in humic acid fraction was very small, and the influence of original concentration of phenanthrene was slight; while for humin fraction, the sorption ratio of phenanthrene at lower initial concentration was significantly higher than at higher one, in addition, the sorption ratio showed a gradually increasing trend, indicated humin fraction as the main domain in charge of the slow sorption. The fitting results of model parameters demonstrated that, sorption nonlinearity of phenanthrene in the natural soil increased in the following order: humic acid fraction< whole soil< humin fraction, and enhanced gradually. Different characteristics of humic acid and humin fractions in the multi-stage kinetics of phenanthrene sorption/distribution further reflected the effects of heterogenerity of soil organic fractions on nonlinear sorption behaviors.

Adsorption↗

PubMed2006

[Sorption and absorption of PAHS to rice roots].

Intact rice roots, ambient air, soil and irrigation water samples were collected from two sites at Baodi and Xinli, Tianjin. The rice roots were separated into nodal roots and lateral roots, which were extracted individually using a three-step sequential extraction procedure to measure the sorbed, strongly sorbed and interior adsorbed fractions. The results show that remarkable difference of PAH contents between the samples from the two sites and relatively higher PAH contents in the lateral roots than those in the nodal roots, around 60% of the total PAHs detected were those absorbed in the root tissues. Specific surface area and lipid content of the roots are main factors influencing PAH contents.

Absorption↗

PubMed2006

Numerical simulation of PAHs sorption/desorption on soil with the influence of Tween80.

In this paper, the influences of inionic surfactant Tween80 on polycyclic aromatic hydrocarbons (PAHs) sorption/desorption on artificially contaminated soil were studied, and gamma model was applied to simulate the influences. Results showed that, with the use of Tween 80, the sorption behaviors of PAHs on soil altered significantly. Adsorbed Tween 80 increased the sorption amount of PAHs while the dissolved Tween80 increased the apparent solubility of PAHs. These two processes exert influences on the sorption coefficient of PAHs in soil-water system, which can be depicted by apparent sorption coefficient. The partition coefficients (the soil/water partition coefficient of PAHs and surfactants obtained from sorption experiments) and statistical parameters used in the amended gamma model were obtained in independent experiments. With these parameters, the gamma model could provide a satisfactory independent prediction of PAHs release from soil to aqueous phase at two surfactant concentrations.

Adsorption↗