Biomedical subjects

Shu Tao

Publications and source records attributed to Shu Tao.

At least 55 records · Page 3Linked to original sources

PubMed2004

Influences of excessive Cu on photosynthesis and growth in ectomycorrhizal Pinus sylvestris seedlings.

Growth and photosynthesis responses were measured for Scots pine (Pinus sylvestris L. cv.) inoculated with ectomycorrhizal fungi (Suillus bovinus) under 6.5 and 25 mg/L Cu treatments to evaluate ectomycorrhizal seedlings' tolerance to heavy metal stress. Results showed that excessive Cu can significantly impair the growth and photosynthesis of pine seedlings, but such impairment is much smaller to the ectomycorrhizal seedlings. Under 25 mg/L Cu treatment, the dry weight of ectomycorrhizal seedlings is 25% lower than the control in contrary to 53% of the non-mycorrhizal seedlings, and the fresh weight of ectomycorrhizal roots was significantly higher than those of non-mycorrhizal roots, about 25% and 42% higher at 6.5 and 25 mg/L Cu treatments respectively. Furthermore, ectomycorrhizal fungi induced remarkable difference in the growth rate and pigment content of seedlings under excessive Cu stress. At 25 mg/L Cu, the contents of total chlorophyll, chlorophyll-a and chlorophyll-b were 30% higher in ectomycorrhizal plants than those in non-mycorrhizal plants. O2 evolution and electron transport of PSI and PSII were restrained by elevated Cu stress. However, no significant improvement was observed in reducing the physiological restraining in ectomycorrhizal seedlings over the non-mycorrhizal ones.

Chlorophyll↗

PubMed2004

[PAHs in airborne particles from Tianjin in winter season].

Total suspended particles (TSP) samples from 13 stations in Tianjin were collected and analyzed for polycyclic aromatic hydrocarbons (PAHs) during 2002 winter. There was significant difference in total PAH concentration among 13 samples. TSP samples from the east Economic Development Area and mid-north districts had the highest contents of PAHs, while Dagang Oil Field had the lowest PAH content. The urban area, south district, and Jixian county had the moderate contents of PAHs. Based on the measured concentration of the PAHs, BaP equivalent (BaPeq) were derived based on Toxicity Equivalent Factors (TEFs) of the PAHs. The total BaPeq values were similar among the samples. The contribution of PAHs with five or six rings contributed 90% of the total toxicity, while they accounted for only 50% of the total concentration.

Air Pollutants↗

PubMed2004

[Polycyclic aromatic hydrocarbons in plant leaves from Peking University campus and nearby in summer season].

Leaves of 6 plants were collected from two sites on and around Peking University campus in summer season of 2003. PAHs in the leaf-wax and tissues were determined simultaneously with leaf-wax content, tissue lipid, specific surface, and stomata density. The results were compared to investigate the possible sources of PAHs in the leaves. For both leaf-wax and tissue samples, levels of PAHs depended on plant species and were lower in the samples from campus than those from outside of campus in short distance to busy traffic, suggesting a significant influence of vehicle emission. The concentrations of PAHs in leaf-wax were 1-2 orders of magnitude higher than those in leaf tissues. While the PAH profiles in the leaf-wax and leaf tissues were similar in general, the relative contents of volatile compounds were higher in the tissues than in the wax. Negative correlations were identified between PAHs concentration in the leaf-wax and the wax content and between the tissue PAH content and stomata density.

Air Pollutants↗

PubMed2003

Interactions of organic contaminants with mineral-adsorbed surfactants.

Sorption of organic contaminants (phenol, p-nitrophenol, and naphthalene) to natural solids (soils and bentonite) with and without myristylpyridinium bromide (MPB) cationic surfactant was studied to provide novel insightto interactions of contaminants with the mineral-adsorbed surfactant. Contaminant sorption coefficients with mineral-adsorbed surfactants, Kss, show a strong dependence on surfactant loading in the solid. At low surfactant levels, the Kss values increased with increasing sorbed surfactant mass, reached a maximum, and then decreased with increasing surfactant loading. The Kss values for contaminants were always higher than respective partition coefficients with surfactant micelles (Kmc) and natural organic matter (Koc). At examined MPB concentrations in water the three organic contaminants showed little solubility enhancement by MPB. At low sorbed-surfactant levels, the resulting mineral-adsorbed surfactant via the cation-exchange process appears to form a thin organic film, which effectively "adsorbs" the contaminants, resulting in very high Kss values. At high surfactant levels, the sorbed surfactant on minerals appears to form a bulklike medium that behaves essentially as a partition phase (rather than an adsorptive surface), with the resulting Kss being significantly decreased and less dependent on the MPB loading. The results provide a reference to the use of surfactants for remediation of contaminated soils/sediments or groundwater in engineered surfactant-enhanced washing.

Adsorption↗

PubMed2003

Fate modeling of phenanthrene with regional variation in Tianjin, China.

A multimedia fate model with spatially resolved air and soil phases was developed and evaluated. The model was used for calculation of phenanthrene concentrations in air, water, soil, and sediment in Tianjin area and transport fluxes between the adjacent bulk phases under steady-state assumption. Both air and soil phases were divided into 3113 individual compartments of 4 km2 each to assess the spatial variation of phenanthrene concentrations and fluxes. Independently measured phenanthrene concentrations in air, water, and soil were used for model validation. The spatial variation in soil was validated using a set of measured phenanthrene concentrations of 188 surface soil samples collected from the area. Most data used either for model calculation or for model validation were collected during the last 5 years. As the results of the model validation, the calculated mean values for phenanthrene concentrations in various bulk phases are in fair agreement with those independently observed and are very close to those calculated using the model without spatial variation. The absolute difference between the calculated and the measured mean concentrations are 0.14, 0.48, and 0.13 log-units (mol/m3) for air, water, and soil, respectively. The spatial distribution patterns of phenanthrene in both air and soil were well modeled. Spatially, however, the model overestimated the soil phenanthrene level at low concentration range and underestimated it at high concentration range. The calculated distribution of phenanthrene in the air matches well with the emission from fossil fuel combustion, while the calculated distribution pattern in the soil is similar to that observed.

China↗

PubMed2003

[Evaluating the fate of gamma-HCH using fugacity model in Tianjin environment].

This study taking Tianjin as the study area calculated the concentration and transfer flux of gamma-HCH in all bulks using Matlab based on the assumption of steady state fugacity model. The calculated values agree well with the observed values, the concentrations of gamma-HCH in air, water, soil, sediment, fish, crop, and vegetable were 1.57 x 10(-11), 7.95 x 10(-7), 1.17 x 10(-4), 4.58 x 10(-4), 6.03 x 10(-4), 1.60 x 10(-4), 6.42 x 10(-5) mol/m3 respectively. The result indicated that the main source of gamma-HCH was agricultural application and wastewater from pesticide industries, the biggest bulk sinks were soil and sediment (accounting for 99% of total amount in the environment). Among all transfer processes deposition and diffusion on the water-sediment and air-soil interface were the primary, and mineralization was the key route for gamma-HCH to disappear in the environment.

China↗

PubMed2003

[Enhanced sorption of naphthalene into bentonites in water containing myristylpyridinium bromide and its mechanism].

The influence of myristylpyridinium bromide (MPB) on sorption behavior of naphthalene into two bentonites in aqueous solution and its mechanism were investigated. The apparent sorption coefficients (Kd*) of naphthalene on two bentonites with surfactant was dependent on MPB equilibrium concentration (X). When X was less than 1/10CMC, the Kd* value increased rapidly with increasing MPB primary concentration (X0) that was mainly contributed to increasing the organic carbon contents (foc) of bentonites for partitioning naphthalene. The Kd* value decreased slowly with increasing X0 when X was intermediate 1/10CMC and 1 CMC, because the adding MPB increased foc for sorption naphthalene was less than MPB monomer for enhancement solubility of naphthalene. Then The Kd* value decreased sharply with increasing X0 when X was larger than 1 CMC, which resulted from that the addition of MPB only increased micelle concentration for enhancement solubility of naphthalene. The mechanism was explained by apparent partition coefficient normalized by foc(i. e. Koc*) for the first time. The relationship of 1/Koc* and X was linear. The value of Koc, Kmn and Kmc can be calculated from the intercept and slope of the linear, which will provide theoretical gist for organobentonite applied on organic contaminant remediation.

Adsorption↗

PubMed2003

[Multimedia fate modeling with spatial resolution for phenanthrene in Tianjin].

Behavior and fate of phenanthrene in various phases in Tianjin were calculated using a multimedia model with spatial resolution under steady-state assumption. Spatial variation of two parameters, namely soil organic carbon content and emission from fossil fuel combustion, were taken into consideration. Both soil and air phases were further divided into 3113 sub-compartments and 6226 equations in total were solved simultaneously under mass-balance assumption. A number of output parameters, therefore, were generated and were used for mapping of phenanthrene concentrations in soil and air, as well as transfer fluxes between compartments. The model was evaluated in two ways. 1. Comparison between the calculated and the observed average concentrations in bulk compartments, and 2. Comparison of spatial distribution of the calculated and the observed phenanthrene concentrations in surface soil. In both cases, the predicted results are in fair agreement with the independently measured values. As the results of the modeling, it was demonstrated that soil and sediment, especially the later, is the primary sink of phenanthrene in the area over 70% of the chemical accumulated in sediment. The spatial distribution pattern of phenanthrene in surface soil depends on content of soil organic matter which prevent the degradation of the material by bacteria. For distribution in ambient air, the dominant controlling factor is the emission.

Air↗

PubMed2002

[Comparison of ISE, ASV and FQ for complexation characterization of river water DOC with copper].

Condition stabilization constants of complexation between naturally occurring organic ligand in river water and copper were measured lgk and compared by using ISE, ASV and FQ methods. The measured lgk results were 2.29-6.47 by ISE, 2.61-6.91 by ASV, and 3.52-4.71 by FQ, respectively. The constants went up with the raise of pH, the decrease of copper content, and the increase of ligand concentration.

Copper↗

PubMed2002

Copper speciation in the gill microenvironment of carp (Cyprinus carpio) at various levels of pH.

The fish gill microenvironment of Cyprinus carpio under stress of copper exposure was investigated. pH and other parameters including free copper activity, alkalinity, and inorganic and organic carbons in the surrounding water (inspired water) and in the gill microenvironment (expired water) were measured or calculated at various levels of pH and varying total copper concentrations. The chemical equilibrium calculation (from MINEQA2) and complexation modeling (mucus-copper) were coupled to calculate both species distribution. The results indicate that the pH in the fish gill microenvironment was different from that in the surrounding water with a balance point around 6.9. The secretion of both CO(2) and mucus was affected in both linear and nonlinear ways when the fish were exposed to elevated concentrations of copper. The complexation capacity of the gill mucus was characterized by a conditional stability constant (logk(Cu-mucus)) of 5.37 along with a complexation equivalent concentration (L(Cu-mucus)) of 0.96 mmol Cu/mg C. For both the fish microenvironment and the surrounding water, the dominant copper species shifted from Cu(2+) to CuCO(3)(0) and to Cu(OH)(2)(0) when the pH of the surrounding water changed from 6.12 to 8.11. The change in copper speciation in the gill microenvironment is smaller than that in the surrounding water due to the pH buffering capacity of the fish gills.

Animals↗

PubMed2002

Uptake of copper complexed to EDTA, diaminoethane, oxalic acid, or tartaric acid by neon tetras (Paracheirodon innesi).

Uptake of copper complexes by fish was studied by exposing neon tetras (Paracheirodon innesi) to solutions containing different concentrations of copper complexed to EDTA, diaminoethane, oxalic acid, or tartaric acid, while other copper species were kept at low and constant levels. The distribution of the copper species in the solution was quantified using chemical equilibrium modeling. It was found that the presence of the organic ligands studied could reduce, but not totally eliminate, the uptake of copper by fish. The rate of the additional uptake besides the contribution of free copper depended on the conditional stability constant of the copper complexes.

Animals↗

PubMed2002

System-level responses of lake ecosystems to chemical stresses using exergy and structural exergy as ecological indicators.

This paper presents the system-level responses of experimental lake ecosystems to three chemical stresses (acidification, copper and pesticide contamination) using exergy and structural exergy as ecological indicators. The results indicate that the doses or toxicity of the three chemical stressors contributed to changes in both exergy and structural exergy. Remarkable changes in exergy and structural exergy occurred under acidic conditions and in the presence of Dursban, 24D-DMA, permethrin, bifenthrin, Carbaryl, TCP, PCP, trichlorethylene, benzene, and high doses of Cu, oil, and hexazinone. This seemed to indicate that the subject ecosystems were seriously contaminated by these chemical stressors. For low doses of Cu, oil, atrazine, HCBP, and hexazinone, exergy and structural exergy were either unchanged or only slightly changed, suggesting that the lake ecosystems were not significantly impacted by these chemical stressors. Discussion of the relationships between ecosystem-level changes and structural and functional changes in stressed lake ecosystems indicates that the above-mentioned ecosystem-level changes were in accordance with the changes in structure and function. The observed changes in exergy and structural exergy were also consistent with Odum's predictions of shortened food chains, reduced resource use efficiency, poor stability, low information, and high entropy in stressed aquatic ecosystems. The findings lead the authors to conclude that it is feasible for exergy and structural exergy to serve as ecological indicators when characterizing the system-level responses of experimental lake ecosystems to chemical stress. These results for experimental lake ecosystems would be extrapolated to actual lakes.

Animals↗

PubMed2002

A fragment constant QSAR model for evaluating the EC50 values of organic chemicals to Daphnia magna.

The quantitative relationship between the median effective concentration (EC50) of organic chemicals to Daphnia magna and the number of molecular fragments was investigated based on experimental EC50 values for 217 chemicals derived from the literature. A fragment constant model was developed based on a multivariate linear regression between the number of fragments and the logarithmically transformed reciprocal values of EC50. Functional correction factors were introduced into the model. The model was verified using an independent set of randomly selected data. The mean residual of the final model was 0.4 log-units. The robustness of the model was discussed based on the results of three jackknife tests.

Animals↗

PubMed2002

Estimation of conditional stability constant for copper binding to fish gill surface with consideration of chemistry of the fish gill microenvironment.

Binding-site concentration and conditional stability constants for copper and fish gill surface interactions were calculated based on the data from the literature. Six scenarios were modeled by including or excluding pH and alkalinity differences between the fish gill microenvironment and the bulk solution and the presence of free mucus in the calculation. We demonstrate that changes in pH or alkalinity, or both, for model input had only a slight influence on the calculated results because of the small difference in pH and alkalinity between the gill microenvironment and the bulk solution under the specific experimental conditions. Inclusion of free mucus in the model, however, led to a large change in the final results. For example, with consideration of free mucus and changes in pH and alkalinity in the model, the calculated site concentration and the stability constant were 0.022 micromol/g wet tissue and log K=8.77, respectively, compared to 0.026 micromol/g wet tissue with log K=7.78 without free mucus and pH/alkalinity change.

Animals↗

PubMed2002

Speciation and bioavailability of EDTA complexed copper in the microenvironment of fish gills.

Carp were exposed to a synthetic solution with varied concentrations of Cu-EDTA and constant levels of other copper species and the amount of copper accumulated in the fish gills was measured. The distributions of copper species in both the bulk solution and the fish gill microenvironment were modeled using MINTEQA2. Under experimental conditions without EDTA, Cu(OH)2 was the most dominant species in the bulk solution while Cu-mucus dominated the gill microenvironment. When Cu-EDTA was added to the solution, copper accumulation in the fish gills increased significantly, suggesting a change in copper speciation. The amount of copper accumulated in the fish gills correlated positively to the concentration of Cu-mucus, rather than to free copper.

Animals↗

PubMed2002

Volatile fatty acids as electron donors for the reductive dechlorination of chloroethenes.

Uses of a mixture of six volatile fatty acids (VFAs) including acetic, propionic, butyric, isobutyric, valeric and isovaleric acids as electron donors for the reductive dechlorination of chloroethenes have been investigated by both microcosm and column studies. The fates of tetrachloroethene (PCE), cis-dichloroethene (cis-DCE) and vinyl chloride (VC) in the presence of VFAs and in the absence of VFAs were respectively documented. The results showed that VFAs stimulated complete reductive dechlorination of chloroethenes, either as direct substrates for the dechlorinating bacteria or via H2 formed during VFAs-degradation. There were sequential utilizations of different VFAs by fermenting bacteria. In the microcosm, propionic acid was the first to be used, followed by acetic, butyric, isobutyric, valeric, and isovaleric acids, and their mean first-order degradation rates obtained were 0.128, 0.048, 0.016, 0.027, 0.025 and 0.003 day(-1), respectively. In the column, propionic acid was the first to be used, followed by butyric and valeric acids, and their calculated first-order degradation rates were 0.833, 0.403 and 0.260 day(-1), respectively.

Carcinogens↗

PubMed2002

Concurrency: a system design approach to environmental management and sustainability.

The lessons of history indicate that mismanagement of natural resources and the environment often leads to potentially adverse consequences. The increasing interest in economic development, particularly in the developing countries of the world coupled with increasing population pressures and the globalization of economic activity is placing noticeable stresses on the ultimate sustainability of both human and environmental systems. Sustainable development is not a new concept. It has been an area of concern for different elements of society for some time. Yet efforts to understand the implications of sustainable development have not, until recently, been formalized. We have focused singularly on economic development and environmental quality as if they were mutually exclusive. This paper focuses on the concept of concurrency as both a conceptual framework and practicable method of understanding and implementing the ecology and economy of sustainability.

Conservation of Natural Resources↗

PubMed2002

[pH of the gill micro-environment of Cyprinus carpio and its effect on the desorption of adsorbed Cu].

pH and CO2 content differences between fish(Cyprinus carpio) gills micro-environment and the ambient environment were investigated using the technique developed by Playle. The effect of the pH change on elutriation of copper sorbed on gibbsite was also studied in view of possible desorption of the metal within the gill micro-environment. It was found that there was no pH difference around pH 8.0 and 0.2-0.4 unit difference was observed between the gills' inspired and the expired water when the ambient pH varied from 8 up to 9.5 or from 8 down to 7.0. Similar trend was detected for CO2. More Cu adsorbed on the gibbsite can be removed by the acidified expired water from the fish gill micro-environment, comparing to the inspired water.

Absorption↗