Kriging and PAH pollution assessment in the topsoil of Tianjin area.
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Air Pollutants, Occupational↗
Biomedical subjects
S Tao
Publications and source records attributed to S Tao.
Changes of copper speciation in maize rhizosphere soil.
Chemical forms of copper in the rhizosphere and bulk soil of maize were investigated using rhizobox cultivation and sequential extraction techniques. The copper accumulations were also determined. The results demonstrated that there were continuous changes in copper fractionation within the maize rhizosphere. Initially, the amount of exchangeable copper increased before dropping below the initial level after 40 days or so. Carbonate associated copper followed a similar trend of change, but with a slower pace than the exchangeable copper. The increase in carbonate associated copper only become evident after 30 days, with the net loss occurring after 60 days. There were also initial increases in oxide bound copper as well as decreases in the organic matter associated copper, both followed by a turnover after 40-50 days. The accumulation of copper in the maize plant was found to be biomass dependent. The amount of accumulated copper absorbed in the plant material exceeded the initial quantity of the exchangeable copper in the soil, revealing a transformation from less bioavailable to more bioavailable fractions. During cultivation, decreases in redox potential and increases in pH, dissolved organic carbon (DOC), and microbial activity in the maize rhizosphere were observed. The change in copper speciation may result from root-induced changes in DOC, redox potential, and microbial activity in the rhizosphere.
Agriculture↗
Medium scale spatial structures of Polycyclic Aromatic Hydrocarbons in the topsoil of Tianjin area.
The spatial distribution patterns of Polycyclic Aromatic Hydrocarbons (PAHs) in soil are important to regional environmental assessment. In this paper, the spatial structural features of sixteen prior PAH compounds in the topsoil of Tianjin area, as well as soil properties, were studied. Results shown that medium scale spatial autocorrelations were well revealed. Spherical models with sills could be used to fit all experimental variograms. The spatial structures of PAHs contents demonstrated significant anisotropy. Air precipitation caused by the combustion of coal was the key factor in the formation of the spatial structural patterns of PAHs in the topsoil of Tianjin area.
China↗
Copper speciation and accumulation in the gill microenvironment of carp ( Cyprinus carpio) in the presence of kaolin particles.
Carp were exposed to copper adsorbed on kaolin particles at various concentrations (0-2.4 mg/L), and net accumulation due to elevated adsorbed copper in the surrounding water was observed. Copper speciation in the water and fish gill microenvironment was modeled in the presence and absence of kaolin using a chemical speciation program (MINTEQA2). The adsorption affinity constants of kaolin for copper at various pH values used in the speciation calculations were experimentally determined, and the quantitative relationship between the affinity constant and pH was modeled. Copper accumulations in fish gills exposed to kaolin-adsorbed copper was then observed. The results indicate that desorption occurred in the fish gill microenvironment due to both mucus competition of copper and slight increase in water pH. Furthermore, the available copper species increased as a result of desorption, causing a net accumulation of Cu by the gills.
Adsorption↗
Characterizing and comparing risks of polycyclic aromatic hydrocarbons in a Tianjin wastewater-irrigated area.
A probability risk assessment was conducted to characterize the ecotoxicity of three polycyclic aromatic hydrocarbons (PAHs), including benzo[a]pyrene, fluoranthene, and phenanthrene, to various species in a wastewater-irrigated area of Tianjin, China. The relative risk of these chemicals was investigated using joint risk probability distribution curves, which were generated based on the distributions of exposure and acute toxicity data. Risk at various exposure levels was discussed. The results indicated that among the three PAHs studied, the overall risk of phenanthrene was the highest, with that of benzo[a]pyrene the lowest, due mainly to their exposure concentrations. For lower exposure levels at which the percentage of species affected was less than 20%, the risk associated with benzo[a]pyrene was clearly higher than that of the other two chemicals.
China↗
A QSAR model for predicting toxicity (LC50) to rainbow trout.
A fragment constant method for prediction of toxicity (LC50) to rainbow trout was developed based on the experimental LC50 values of 258 chemicals obtained from the literature. The dataset was randomly divided into a training set and a validation set for purposes of model development and validation. The final model was established using all of the experimental LC50 values by pooling the two sets together. The coefficient of the determination for the final model was 0.9495 with a mean residual of 0.42 log-units. The model's robustness was tested using jackknife tests.
Animals↗
Determination of PAHs in wastewater irrigated agricultural soil using accelerated solvent extraction.
A procedure was developed for determination of 16 polycyclic aromatic hydrocarbons (PAHs) in heavily contaminated paddy soil from wastewater irrigated farmland near Tianjin. The sample was distilled with accelerated solvent extraction (ASE), purified by a silica gel column, and measured with GC/MS. The optimal conditions for the distillation were at 140 degrees C (1500 psi) with a 1:1 mixture of dichloromethane and acetone for 5 min. Application of cyclohexane for extract transfer improved the recovery when the ASE extraction was followed by a silica gel cleanup procedure. Recoveries from the method for 16 PAHs ranged from 57-140% with the coefficients of variation of the results ranging from 0.35% to 5.75%. The total 16 PAHs in a composite sample collected from a wastewater irrigated paddy field near Tianjin was 3.90 mg/kg.
China↗
Serum cholesterol changes from 1983-1984 to 1993-1994 in the People's Republic of China.
BACKGROUND AND AIM: Increasing cardiovascular disease (CVD) mortality in the People's Republic of China (PRC) led to the 1981 establishment of the PRC-USA Study of Cardiovascular and Cardiopulmonary Epidemiology which, among other objectives, is concerned with the correlates of CVD morbidity and mortality in Chinese populations among other objectives. This report describes changes in total cholesterol (TC) levels in four PRC populations from 1983 to 1993 and identifies factors related to the changes. METHODS AND RESULTS: Population screenings carried out in 1983-1984, 1987-1988 and 1993-1994 involved the collection of demographic data, specimens (including blood), medical history and physical examination data. The data from cohort and independent samples were used to assess TC changes in urban and rural men and women over the decade, with and without adjustment for age and body mass index (BMI) changes. For Guangzhou men and women, the cohort analyses (aged 35-54 at baseline) showed increases in TC of 10-20 mg/dL after adjustment for age and changes in BMI; the independent sample analyses (aged 35-44) also showed higher average TC levels in 1993-1994 than in 1983-1984. For the Beijing cohorts, the results showed decreases in TC during the decade in men, an increase in TC in urban women and no change in rural women; the independent sample analyses indicated declines in TC for Beijing men and women. Possible reasons for the Guangzhou TC increases are economic growth, and dietary and BMI changes. The mean age-adjusted BMI significantly increased (5-10%) over the 10-year period in all of the studied groups. CONCLUSIONS: TC increased 10-20 mg/dL in Guangzhou men and women, probably as a result of socioeconomic development during the decade. The inconsistent patterns of TC changes in Beijing require further study.
Adult↗
Lake ecosystem health assessment: indicators and methods.
A set of ecological indicators including structural, functional, and system-level aspects were proposed for a lake ecosystem health assessment, according to the structural, functional, and system-level responses of lake ecosystems to chemical stresses including acidification, eutrophication and copper, oil and pesticide contamination. The structural indicators included phytoplankton cell size and biomass, zooplankton body size and biomass, species diversity, macro- and micro-zooplankton biomass, the zooplankton phytoplankton ratio, and the macrozooplankton microzooplankton ratio. The functional indicators encompassed the algal C assimilation ratio, resource use efficiency, community production, gross production/respiration (i.e. P/R) ratio, gross production standing crop biomass (i.e. P/B) ratio, and standing crop biomass unit energy flow (i.e. B/E) ratio. The ecosystem-level indicators conisisted of ecological buffer capacities, energy, and structural energy. Based on these indicators, a direct measurement method (DMM) and an ecological modeling method (EMM) for lake ecosystem health assessment were developed. The DMM procedures were designed to: (1) identify key indicators; (2) measure directly or calculate indirectly the selected indicators; and, (3) assess ecosystem health on the basis of the indicator values. The EMM procedures were designed to: (1) determine the structure and complexity of the ecological model according to the lake's ecosystem structure; (2) establish an ecological model by designing a conceptual diagram, establishing model equations, and estimating model pararmeters; (3) compare the simulated values of important state variables and process rates with actual observations; (4) calculate ecosystem health indicators using the ecological model; and, (5) assess lake ecosystem health according to the values of the ecological indicators. The results of a case study demonstrated that both methods provided similar results which corresponded with the lake's actual trophic state.
Animals↗
Simulation of acid-base condition and copper speciation in the fish gill microenvironment.
pH, alkalinity, and mucus content in the fish gill microenvironment of carp (Cyprinus carpio) were measured by exposing fish to copper at various water pH levels using an apparatus which separates inspired and expired water. The relationship between pH levels inside and outside of the gill microenvironment, between pH and alkalinity, and between mucus secretion, pH, and copper exposure concentration were modeled. Copper speciation in the surrounding water and in the fish gill microenvironment was simulated using MINTEQA2 chemical equilibrium calculation software. The results of the modeling for pH, alkalinity, and mucus calculation were then adopted as inputs for purposes of parameter identification in the speciation modeling. The differences observed in the copper species distribution between that of the fish gill microenvironment and the surrounding water were based on the speciation modeling. The change in copper bioavailability for fish uptake was also examined. The results indicate the presence of an experimental pH balance point at 6.9, where the pH in the fish gill microenvironment is identical to that of the surrounding water. The observed deviation range in pH levels between that found at the gills and that of the surrounding water varied from -0.4 to 0.8 units. A sinusoidal model was developed for calculation of gill pH based on the pH of the surrounding water. Models calculating alkalinity either in the gill microenvironment or in the surrounding water and for estimating mucus secretion were also developed. The results of the chemical equilibrium calculations demonstrate that, within a pH range of 6-9, the dominant species of copper in bulk solution shifted from free ions to that of the hydroxo complex. With respect to the fish gill microenvironment, the dominant species found under acidic conditions were the mucus copper complex and free ions. Because of the influence of mucus complexation and pH change, bioavailable copper species in the fish gill microenvironment were significantly lower than that in the bulk solution, especially under acidic conditions.
Acid-Base Equilibrium↗
Characteristic hydrogen concentrations for various redox processes in batch study.
The dissolved hydrogen concentrations under various redox processes were investigated based on batch experiments. Chloroethenes including tetrachloroethene (PCE), cis-dichloroethene (cis-DCE) and vinylchloride (VC) were respectively used as culture substrates. For each chloroethene, a series of bottles were prepared with the additions of different electron acceptors or donors such as nitrate, manganese oxide, ferrous iron, sulfate, carbondioxide and volatile fatty acids. Hydrogen concentrations as well as redox species were measured over time to ensure the achievements of characteristic hydrogen levels in various enrichment batches. The results showed that redox processes with nitrate, manganese oxide and ferric iron as the electron acceptors exhibited hydrogen threshold values close to PCE/TCE dechlorination, whereas cis-DCE and VC dechlorinations exhibited hydrogen threshold values in the range of sulfate reduction and methanogenesis, respectively. Characteristic hydrogen concentrations for various redox processes were as follows (nM): denitrification, 0.1-0.4; manganese reduction, 0.1-2.0; iron reduction, 0.1-0.4; sulfate reduction, 1.5-4.5; methanogenesis, 2.5-24; PCE/TCE dechlorination, 0.6-0.9; eis-DCE dechlorination, 0.1-2.5; and VC dechlorination, 2-24.
Biodegradation, Environmental↗
QSAR modeling of bioconcentration factors in fish based on fragment constants and structural correction factors.
The quantitative structure-activity relationship between the BCF and fragment constant of organic chemicals was studied using a database containing 337 experimental BCF values. The database covered a large variety of chemicals ranging from the very hydrophobic to the very hydrophilic with logKow values between 0.39 and 8.60. The structural features affecting the BCFs were identified and evaluated during a preliminary modeling. A final linear multivariate regression model was derived that was able to account for as much as 98.0% of the variation in the experimental BCF values. The mean absolute error for the final model was 0.315 log-units. In addition, the predictability and robustness of the model was also evaluated.
Animals↗
Multi-country comparison of plasma lipid relationship to years of schooling in men and women.
BACKGROUND: The association between coronary heart disease (CHD) and social status has differed among societies in strength and direction. As years of schooling is a major determinant of socioeconomic status and dyslipidaemia a major CHD determinant, the purpose of this investigation is to estimate the association of years of schooling with plasma lipids and lipoproteins among samples from five countries representing different cultures, socio-political systems and stages of economic development. METHODS: Men and women from Chinese, Polish, Russian, Israeli and US samples were studied. Years of schooling were analysed both as a multi-category ordinal variable and divided into two strata: less than the equivalent of high school and greater than or equal to high school equivalence. Fasting plasma cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol and triglycerides were compared across years of schooling strata within each country. Lipid levels were computed unadjusted and then adjusted for age and lipid risk factor variables. RESULTS: Total cholesterol, LDL cholesterol, and triglycerides varied directly with years of schooling in Chinese, Polish and Russian men, and in contrast varied inversely with years of schooling among US white men. The HDL cholesterol varied inversely with years of schooling for Chinese, Polish, and Russian men, but varied directly with years of schooling among US white men. The lipid differences between men of high versus low years of schooling were not explained by age, body mass index, smoking, alcohol consumption or blood pressure medication use. Findings were less consistent for women and for Israelis and US blacks of both genders. CONCLUSIONS: Lipid and lipoprotein levels consistent with atherogenicity varied directly with years of schooling in Chinese, Polish, and Russian samples. Opposite trends were present in US whites. These findings are consistent with a hypothesized influence of social status on CHD risk differing among populations in relation to stages in societal economic development.
Asia↗
[Computer simulation of HA influence on copper bioavailability to the fish gills].
Copper speciation in the gill microenvironment of neon terris (Paracheirodon innesi) and the influence of humic acid and pH on copper bioavailability were investigated using exposure experiment and chemical equilibrium calculation. It was found that the copper speciation was changed because of the influence of the humic acid. With the existence of humic acid, the dominant species of copper in the bulk solution was humic acid complexed copper. However, humic acid complexed copper along with mucus complexed copper dominated the fish gill microenvironment. Consequently, the bioavailable copper species both in the bulk solution and in the fish gill microenvironment were significantly reduced by humic acid. The result of the modeling also indicated that the influence of pH was more significant under alkaline condition.
Animals↗
[Estimation of LC50 of chemicals to rainbow trout by fragment constant method].
A fragment constant model for prediction of 96 h LC50 of chemicals to rainbow trout was developed based on measured experimental data of 258 chemicals collected from the literature. The accuracy and the robustness of the model were discussed. The coefficient of determination of the model is 0.9495 and the mean residual is 0.42 log-unit. The model is robust for both individual chemical or chemical class.
Animals↗
Excessive Cu and Zn affecting on distribution of the metals and activities of glycolytic and nitrogen incorporating key enzymes in mycelia of ectomycorrhizal fungi Suillus bovinus.
Concentration of copper and zinc in isolated Suillus bovinus mycelia, used nutrient solution and 0.5 mol/L EDTA mycelia washing solution were measured to investigate the distribution of heavy metals in mycelia growth in excess copper or zinc nutrient solution. Treated with zinc, most of added zinc maintained in used solution, and 9.8%/14.6% was in/on mycelia in treatment, and in treatment 2 was 3.9%/8.0% in/on mycelia. In the copper applications, copper stimulated in more than on mycelia, i.e., 25.9%/4.5% in/on mycelia in treatment, and 7%/18.8% in/on mycelia while most of copper retained in used nutrient solution. Certain amount of copper or zinc uptake by mycelia led to pronounced influence on glycolysis and nitrogen incorporating process of Suillus bovinus, while the tested enzymes kept constant in treatment. In crude extracts of copper treatment 2 mycelia, activities of HK, PFK and GS were inhibited and decrease to 63%, 48% and 38% and GIDH increased by 68% of the control, respectively. The behaviors of these tested enzymes toward zinc corresponded in general with that towards copper. The potential protection of Suillus bovinus for its host plant under excess copper or zinc threaten was discussed.
Basidiomycota↗
[A new method of bone defect repairing after bone cyst curettage].
OBJECTIVE: To introduce a new method of bone defect repairing after bone cyst curettage. METHODS: Eight cases with bone cyst were treated with this new method. The pieces of autogenous periosteum were implanted into the hematoma within the enveloped bone defect created after the bone cyst curettage. Among these patients, there were 5 males and 3 females, aged from 14 to 36 years old. All the lesions located in the upper of femur except one being located in humerus. The results were evaluated through the postoperative radiological findings with the preoperative ones and analysis of clinical functions. RESULTS: All the patients were followed up for 2 to 11 years. X-ray films showed that osteogenesis developed well and that the enveloped bone defects had been repaired. No recurrence was found and the function of the affected limbs were maintained. CONCLUSION: Autogenous periosteum grafting is effective in the treatment of solitary bone cyst.
Adolescent↗
Effect of vapor-flame treatment on plasma sprayed hydroxyapatite coatings.
A vapor-flame treatment was developed to modify the crystallinity of the as-sprayed hydroxyapatite (HA) coatings. The effects of the treatment on composition, structure, and properties of HA coatings were investigated. Results showed that the vapor-flame treatment is simple and efficient to adjust the crystallinity of as-sprayed HA coating. Its crystallinities can be raised from 53.5 to 98.7% in 3-7 min. The porosities of coatings increased with an increase in the vapor-flame treating time. The microhardness of coating decreased as a result of this treatment. It may be explained in terms of the extent of microcracks caused by recrystallization of amorphous HA and relaxation of stress of the coating. The porosity, bonding strength, and hardness of HA coatings treated for 7 min were 15.7%, 32.0 MPa (300 microm thickness), and 1.9 GPa, respectively.
Coated Materials, Biocompatible↗