Accumulation and distribution of polycyclic aromatic hydrocarbons in rice (Oryza sativa)

Various tissues of rice plants were sampled from a PAH contaminated site in Tianjin, China at different growth stages of the ripening period and analyzed for PAHs. PAHs were much higher in roots than in the exposed tissues. Grains and internodes accumulated much smaller amounts of PAHs than leaves, hulls or ear axes. No specific gradient trends along roots, stem, ear axes, and grains were observed, suggesting that systematic translocation among them is unlikely. Over the ripening period, PAH concentrations were increased in rice roots and decreased in most above-ground tissues. Significant correlations between PAH and lipid contents can only be observed during full mature stage. The spectra of individual PAH compounds in rice organs including roots were similar to those in air, rather than those in soil. There was also a significant correlation between bioconcentration factor (BCF, plant over air) and octanol/air partitioning coefficient (Koa).

Uptake of vapor and particulate polycyclic aromatic hydrocarbons by cabbage

Polycyclic aromatic hydrocarbons (PAHs) in cabbage (aerial part), air (gas and particles) and soil samples collected from two sites in Tianjin, China were measured. Although the levels of PAHs in all samples from the heavily contaminated site B were higher than those from the less contaminated site A, the PAH profiles were similar, suggesting the similarity in source type. PAH concentrations in cabbages were positively correlated to either gas or particle-bound PAHs in air. A multivariate linear regression with cabbage PAH as a function of both gas and particle-bound PAHs in air was established to quantitatively characterize the relationship between them. Inclusion of soil PAH concentrations would not improve the model, indicating that the contribution of soil PAHs to cabbage (aerial part) accumulation was insignificant.

Particle size distributions of polycyclic aromatic hydrocarbons in rural and urban atmosphere of Tianjin, China

The size distributions of 16 polycyclic aromatic hydrocarbons (PAHs) and particle mass less than 10 microm in aerodynamic diameter (Dp) were measured using a nine-stage low-volume cascade impactor at rural and urban sites in Tianjin, China in the winter of 2003-2004. The particles exhibited the trimodal distribution with the major peaks occurring at 0.43-2.1 and 9.0-10.0 microm for both urban and rural sites. The concentrations of the total PAH (sum of 16 PAH compound) at rural site were generally less than those of urban site. Mean fraction of 76.5% and 63.9% of the total PAH were associated with particles of 0.43-2.1 microm at rural and urban sites, respectively. Precipitation, temperature, wind speed and direction were the important meteorological factors influencing the concentration of PAHs in rural and urban sites. The distributions of PAHs concentration with respect to particle size were similar for rural and urban samples. The PAHs concentrations at the height of 40 m were higher than both of 20 and 60 m at urban site, but the mass median diameter (MMD) of total PAH increased with the increasing height. The mid-high molecular weight (278 >or= MW >or= 202) PAHs were mainly associated with fine particles (Dp <or= 2.1 microm), whereas low molecular weight (128 >or=MW >or=178) PAHs were distributed in both of fine and coarse particle. The fraction of PAHs associated with coarse particles (Dp>2.1 microm) decreased with increasing molecular weight. The relatively consistent distribution of PAHs seemed to indicate the similar combustion source of PAHs at both of rural and urban sites. The fine differences of concentration and distribution of PAHs at different levels at urban site suggested that the different source and transportation path of particulate PAHs.

Modeling the dynamic changes in concentrations of gamma-hexachlorocyclohexane (gamma-HCH) in Tianjin region from 1953 to 2020

A level IV fugacity model was used to simulate the dynamic changes of gamma-hexachlorocyclohexane (gamma-HCH) concentrations in environmental media in Tianjin, China. A similar model (level III) was previously used and validated under steady state conditions; this paper explores its dynamic behavior. Application of the level IV fugacity model has been validated using independently observed gamma-HCH concentrations in various media during the early 1980s and during 2001. Sensitivity analysis was conducted using coefficient-of-variation normalized sensitivity coefficients. The model was also subject to uncertainty analysis using Monte Carlo simulation. It was found that concentrations of gamma-HCH reached within 95% of their steady-state levels in all media after less than 15 years. Around one order-of-magnitude decreases in gamma-HCH concentrations in various media occurred between 1993 and 2001. We project that gamma-HCH concentrations will decrease another 1.7-1.9 orders of magnitude to reach 1.1 (0.9-1.2) x 10(-14), 2.7 (2.5-3.0) x 10(-10), 1.2 (1.1-1.3) x 10(-7), and 6.1 (5.4-6.8) x 10(-8) mol/m(3), in air, water, soil, and sediment, respectively, by 2020. The sensitivities and true uncertainty of the model are discussed.

Source diagnostics of polycyclic aromatic hydrocarbons based on species ratios: a multimedia approach

Often, the sources of polycyclic aromatic hydrocarbons (PAHs) in environmental media can be identified by comparing the ratios of concentrations of selected pairs of PAH congeners in the source emissions to the ratios in the contaminated environmental media. However, these ratios can be altered significantly due to differences in the transport of the PAH compounds in a multimedia environment. To examine such changes, a fugacity model was applied to PAH ratios in a model environment. A linear relationship between the rate of emission and the bulk media concentration was identified for each PAH compound in an environmental medium at steady state and was quantified by a receptor-to-source ratio (RRS). It was demonstrated that the RRS values of the two congeners usually differ significantly. Consequentially, PAH ratios changed remarkably from the source emissions to various environmental media. A site-specific rectification factor (RF) was defined as the ratio of the two RRS values of the paired congeners for a specific PAH ratio in a given medium, which can be applied to account for the ratio changes in a multimedia environment. The PAH ratio changes were further verified with the surface soil data collected from Tianjin, China, and the observed changes of PAH ratios were compared favorably with the model predictions. The sensitivity analysis revealed that PAH ratios of the low molecular weight compounds were less stable. The most influential parameters controlling PAH ratios were those pertaining to dry precipitation, surface-to-air diffusion, degradation in air and water, and exchange between water and sediment.

Health risks of heavy metals to the general public in Tianjin, China via consumption of vegetables and fish

Consumption of vegetables and fish contaminated with the heavy metals Cu, Zn, Pb, Cd, Hg, and Cr is the most likely route for human exposure in Tianjin, China. Health risks associated with these heavy metals were assessed based on the target hazard quotients (THQs), which can be derived from concentrations of heavy metals in vegetables and fish consumed in four districts (Dong Li, Xi Qing, Jin Nan, and Bei Chen) and the urban area of Tianjin, China. Individual metal THQ (<1) values indicate the relative absence of health risks associated with intake of a single heavy metal through consumption of either contaminated vegetables or fish only. However, consumption of both vegetables and fish would lead to potential health risks especially for children, since individual THQs for vegetables and fish would sum up to almost 1. If individual THQs resulting from crops consumption are considered, the health risks would be greater for children since the THQ values will always be >1. Risk contribution from Cr is minimal compared to the other elements. Hg is the major risk contributor for children in Bei Chen since the THQ contribution amounts to about 45% of the total THQ values due to vegetables and fish consumption. The health risk to adults in Ding Li is ascribed mainly to the intake of Cd by vegetables and fish consumption, which contributes a substantial fraction to the total THQ (about 51%).

Fractional optical vortex beam induced rotation of particles

We experimentally demonstrate optical rotation and manipulation of microscopic particles by use of optical vortex beams with fractional topological charges, namely fractional optical vortex beams, which are coupled in an optical tweezers system. Like the vortex beams with integer topological charges, the fractional optical vortex beams are also capable of rotating particles induced by the transfer of orbital angular momentum. However, the unique radial opening (low-intensity gap) in the intensity ring encompassing the dark core, due to the fractional nature of the beam, hinders the rotation significantly. The fractional vortex beam's orbital angular momentum and radial opening are exploited to guide and transport microscopic particles.

Human exposure and health risk of alpha-, beta-, gamma- and delta-hexachlorocyclohexane (HCHs) in Tianjin, China

The dynamic exposures to HCHs of individuals born between the years 1913 and 1993 in Tianjin have been simulated by connecting a fugacity model (IV) with a multimedia exposure model. Ingestion is the most important pathway for human beings to take up HCHs, and concentrations in the human body correlate with body weight changes. Accumulations of HCHs were derived assuming that the degradation in human body behaved linearly. The health risk of exposure to HCHs was measured using cancer risk and loss of life expectancy (LLE), and LLE was modified from its original definition to incorporate a dynamic calculation that takes variances in exposure into account. Monte-Carlo simulations were run to analyze the uncertainties of the model.

Polycyclic aromatic hydrocarbons in dustfall in Tianjin, China

Atmospheric dustfall samples from 23 locations in Tianjin, China, were collected and analyzed for 16 polycyclic aromatic hydrocarbons (PAHs) classified by the Environmental Protection Agency as priority pollutants from March 2002 to March 2003. SigmaPAH16 (sum of 16 PAH compounds) concentrations in the dustfall collected during heating season ranged from 2.5 to 85.5 mug/g, while that during the non-heating season varied from 1.0 to 48.2 microg/g dry weight. The dominant components in the heating season included naphthalene, phenanthrene, fluoranthene, and chrysene, while naphthalene, fluorene, phenanthrene, and fluoranthene were dominant during the non-heating season. Compared with the non-heating season, the heating season was characterized by a higher fraction of high-molecular-weight PAHs with four to six rings with exception of the samples from the east industrial area. The east industrial area had more significant correlations between individual PAH compounds, and more discrete triangular components of three-, four-, five- and six-ring PAHs. No significant correlations were observed between the PAHs concentrations and total organic carbon (TOC) in the dustfall samples. The deposition fluxes of sigmaPAH15 (sum of 15 PAHs except naphthalene), sigmaPAH6 (sum of 6 carcinogenic PAHs recommended by IARC) and benzo[a]pyrene (BaP) from atmospheric deposition to the whole area were estimated as 1911, 196, and 53 microg/m2/year, respectively. The deposition rates for PAH compounds in the east industrial area were higher than those in the urban and rural areas. Furthermore, the deposition contribution of PAHs during domestic heating season in winter was not significant relative to the annual inputs.

Organochlorine pesticides in agricultural soil and vegetables from Tianjin, China

Samples of eight types of vegetables, the rhizosphere soils, and bulk soils were collected from two sites (A and B) in Tianjin, China for the determination of hexachlorocyclohexane isomers (HCHs) and dichlorodiphenyltrichloroethane and metabolites (DDXs). The average concentrations of total HCHs and DDXs in the bulk soils were 3.6 and 80.1 ng/g for site A and 102 and 235 ng/g for site B, respectively. Relative accumulations of HCHs and DDXs in the rhizosphere soil from site A but not site B were demonstrated. The concentrations of total HCHs and DDXs in vegetable roots were 3.6-60 and 4.2-73 ng/g for site A and 15-152 and 7.1-136 ng/g for site B, respectively. Difference in bioaccumulation among various vegetables, especially between tuber and fibrous vegetables was significant. DDXs in spinach and cauliflower from site B and lindane (gamma-HCH) in cauliflower from both sites and violet from site B exceeded the maximum residual limits. Linear correlation of log-transformed HCHs and DDXs contents between the vegetable roots and the rhizosphere soils suggests the direct uptake of HCHs and DDXs.

The Biomolecular Interaction Network Database and related tools 2005 update

The Biomolecular Interaction Network Database (BIND) (http://bind.ca) archives biomolecular interaction, reaction, complex and pathway information. Our aim is to curate the details about molecular interactions that arise from published experimental research and to provide this information, as well as tools to enable data analysis, freely to researchers worldwide. BIND data are curated into a comprehensive machine-readable archive of computable information and provides users with methods to discover interactions and molecular mechanisms. BIND has worked to develop new methods for visualization that amplify the underlying annotation of genes and proteins to facilitate the study of molecular interaction networks. BIND has maintained an open database policy since its inception in 1999. Data growth has proceeded at a tremendous rate, approaching over 100 000 records. New services provided include a new BIND Query and Submission interface, a Standard Object Access Protocol service and the Small Molecule Interaction Database (http://smid.blueprint.org) that allows users to determine probable small molecule binding sites of new sequences and examine conserved binding residues.

Contamination of rivers in Tianjin, China by polycyclic aromatic hydrocarbons

Tianjin urban/industrial complex is highly polluted by some persistent organic pollutants. In this study, the levels of 16 priority polycyclic aromatic hydrocarbons (PAHs) were tested in sediment, water, and suspended particulate matter (SPM) samples in 10 rivers in Tianjin. The total concentration of 16 PAHs varied from 0.787 to 1943 microg/g dry weight in sediment, from 45.81 to 1272 ng/L in water, and from 0.938 to 64.2 microg/g dry weight in SPM. The levels of PAHs in these media are high in comparison with values reported from other river and marine systems. Variability of total concentrations of PAHs in sediment, water, and SPM from nine different rivers is consistent with each other. No obvious trends of total PAHs concentration variations were found between upstream and downstream sediment, water, and SPM samples for most rivers, which indicate local inputs and disturbances along these rivers. The spatial distributions of three-phase PAHs are very similar to each other, and they are also similar to those found in topsoil. However, their chemical profiles are significantly different from that of topsoil. The change of profiles is consistent with the different aqueous transport capability of 16 PAHs. Low molecular weight PAHs predomination suggests a relatively recent local source and coal combustion source of PAHs in the study area.

Transfer of 'pure' on-axis spin angular momentum to the absorptive particle using self-imaged bottle beam optical tweezers system

Optical tweezers system has aggrandized the understanding of the light-matter interaction and is used frequently to transfer angular momentum of light to microscopic particles. Here we demonstrate experimentally, for the first time to our knowledge the use of self-imaged bottle beam in an optical tweezers system and we report the mechanical transfer of 'pure' on-axis spin angular momentum to an absorptive particle. The self-imaged bottle beam has embedded optical bottles or null intensity points where the absorptive particles are trapped and the transfer of spin angular momentum is accomplished without the default transfer of orbital angular momentum of a singular beam, which are used conventionally to trap absorptive particles.

Treatment of atrazine by integrating photocatalytic and biological processes

This research examines the degradation of atrazine by photocatalytic oxidation (PCO) under different experimental conditions. Deisopropylatrazine, deethylatrazine and deethyldeisopropylatrazine were formed as major intermediates based on gas chromatography-mass spectrometry. The reaction mixture was found to be toxic towards two bioassays, i.e. the Microtox and amphipods survival tests even when atrazine was completely degraded by PCO within 2 h under optimized conditions. The results indicate that adding H2O2 could significantly enhance the degradation of atrazine by PCO. Ammeline, ammelide and cyanuric acid (CA) became the major intermediates/products as detected by high performance liquid chromatography from 6th to the 40th h of PCO treatment. After 72 h PCO treatment, only CA was detectable in the reaction mixture. Further degradation of CA was carried out by a newly isolated CA-degrading bacterium, Sphingomonas capsulata. The photochemical pretreatment integrated with microbial degradation lead to the complete degradation and detoxification of atrazine.

Optimization of photocatalytic oxidation of 2,2',3,3'-tetrachlorobiphenyl

Polychlorinated biphenyls (PCBs) are wide spread environmental pollutants. This research focused the optimum physico-chemical conditions under which photocatalytic oxidation (PCO) can be used to degrade 2,2',3,3'-tetrachlorobiphenyl (tetra-CB). Among the optimal physico-chemical conditions studied were UV intensity, hydrogen peroxide (H2O2) and titanium dioxide (TiO2) concentrations, initial pH, and possible reaction intermediates were also determined. The results indicate that the optimal physico-chemical conditions necessary for the degradation of tetra-CB by PCO were UV intensity at 3.16 mW/cm2, 30 mM of H2O2 and 100 mg/l of TiO2. In contrast to the results of PCO studies on other organic compounds, the optimum pH for PCO degradation of tetra-CB was 5.5. The removal efficiency was also higher under acidic conditions than alkaline conditions. Although degradation intermediates such as 1,3-bis(1,1-dimethylethyl)benzene, 2,4-bis(1,1-dimethylethyl)phenol, and 3,5-di-tert-butyl-4-hydroxybenzaldehyde were identified at an early stage in the reaction process, they were not completely degraded even after 7h of PCO reaction.

Evaluation of factors influencing root-induced changes of copper fractionation in rhizosphere of a calcareous soil

Major factors influencing the root-induced copper fractionation changes within the rhizosphere of maize, wheat, pea, and soybean seedlings were evaluated using a contaminated calcareous soil. The effects of acidification, alkalization, and introduction of root exudates were investigated by addition of acid, alkaline and root exudates from solution cultures, prior to incubation and copper fractionation. Raw and sterilized soils were compared for changes of copper fractionation in the rhizosphere using rhizoboxes with maize, wheat, pea and soybean seedlings. The results indicated that the general trend in considerable changes was similar among the plant species studied. The rhizosphere experienced a depletion of carbonate associated and organic bound copper along with an accumulation of exchangeable and Fe-Mn oxide bound copper. The resulting significant influence of root exudates on copper fractionation appears to have been produced through complexation rather than acidification or alkalization. The increase in exchangeable copper in rhizosphere was strengthened by microorganisms.

Residues of hexachlorocyclohexane isomers and their distribution characteristics in soils in the Tianjin area, China

Hexachlorocyclohexane (HCH) has a history of use in China. This paper presents the results of an investigation of HCH residue isomers and their distribution characteristics in soils near Tianjin, China. One hundred eighty-eight soil samples were collected from the Tianjin area. Four HCH isomers-alpha-HCH, beta-HCH, gamma-HCH, and delta-HCH-were detected using gas chromatography for all samples. Concentrations of the sum HCH ranged from 1.3 to 1095 ng g(-1), among which beta-HCH accounted for 52.5%. In addition, residues of HCH within Tianjin's urban areas were found to be higher. No significant differences were found between the residues of HCH in soils from waste irrigation areas and those in other areas. Total organic carbon content was determined to impact the residue levels of HCH in soils, while pH value and clay content were not related to concentrations of HCH. In general, all HCH isomers in soil samples had abnormally high residue levels, possibly the result of continuous use of HCH in this area.

Sample purification for analysis of organochlorine pesticides in sediment and fish muscle

The methods of sample purification for determinations of organochlorine pesticides (OCPs) in sediment and fish muscle were investigated in this study. A two-step procedure with preliminary cleanup and florisil column fraction was adopted. The working conditions of florisil column were firstly optimized. As to preliminary cleanup, liquid-liquid extraction by mixture of dimethyl formamide (DMF) and hexane and sulphonation by concentrated sulfuric acid were applied respectively and compared for the studied samples. The results indicated that liquid-liquid distribution could effectively separate lipids from fish muscle extracts, while failed in elimination of chlorophyll extracted from the relicts of hydrophytes in the sediment sample. In view of the sample appearance and clarity of gas chromatogram, sulphonation was more suitable to purify the sediment sample, however, the recoveries of the spiked standards were poor. The use of eluting solvent with stronger polarity could improve the corresponding recoveries significantly. Due to complete loss of Dieldrin, Endrin, and Endrin aldehyde after sulphonation, this pretreatment was improper to the three components. Sulfur, as the particular disturbing element in sediment, could be removed sufficiently by addition of activated copper powder. The relevant detection limits of the selected methods for OCPs in the studied substrates were also provided.

Uncertainty analysis of parameters for modeling the transfer and fate of benzo(a)pyrene in Tianjin wastewater irrigated areas

A Monte Carlo simulation for uncertainty analysis of three key parameters (local coal consumption rate Q(1L), dry deposition velocity of aerosol particulate Kp and biodegradation rate of benzo(a)pyrene in soil and sediment K(R3)) was conducted in this study. Results of the simulation indicate that the three parameters were influenced by uncertainty and that all equilibrium concentrations in the four bulk compartments and various sub-compartments were log-normally distributed. However, the results also indicated that among the six primary transfer fluxes, erosion associated with solids in soil and deposition associated with solids in water, along with output from sewers were also log-normally distributed, while deposition from air to soil and biodegradation in soil and sediment followed normal distributions. The effect of uncertainty on the model results of the three key parameters was derived using a comparison of upper and lower of confidence interval boundaries at the 95% level of confidence. The results reveal that uncertainty in the key parameters had a more significant influence on equilibrium concentrations of the chemical in the bulk compartments of soil and sediment than on concentrations in the other two bulk compartments, various sub-compartments and the six predominant transfer fluxes.

Coregionalization analysis of heavy metals in the surface soil of Inner Mongolia

Due to potential problems associated with their deficiencies or toxicities, heavy metals in soils are of great environmental concern. To evaluate heavy metal contents and their relationships in the surface soil of Inner Mongolia, soil samples were collected from 344 sites and contents of copper, lead, zinc, cadmium, nickel, chromium, mercury, cobalt, vanadium and manganese were determined. In this article, coregionalization of these ten heavy metals is investigated using factorial kriging. Vegetation type, parent material type and soil pH, with respective characteristic ranges of 200, 400 and over 1000 km, are identified as the primary factors that control the spatial distribution of soil heavy metals. At the scale of 200 km, heavy metal relationships mainly reflect the result of biocycling. Their relationships at the intermediate scale (400 km) are thought to be derived from the atomic substitution of metals in the parent materials. Effects of soil pH on the adsorption of heavy metals by soil organic materials could explain their relationships at the large spatial scale (over 1000 km).

Polycyclic aromatic hydrocarbons (PAHs) in agricultural soil and vegetables from Tianjin

Several types of vegetables were collected from two contaminated sites in Tianjin, China. The bulk soil and the rhizosphere soil samples were also collected from the same plots. Sixteen PAHs in the samples were measured. The total concentrations of PAH16 in the bulk soil from the two sites were 1.08 and 6.25 microg/g, respectively, with similar pattern. The concentrations of PAH16 and individual compounds in the rhizosphere were significantly higher than those in the bulk soil with mean values of 2.25 and 7.82 microg/g for the two sites, respectively. The contents of both total and dissolved organic matter in the rhizosphere were also higher than those in the bulk soil. Almost all PAH compounds studied were detected in both roots and aerial parts of the vegetables studied. Abundance of higher molecular weight PAHs in vegetable, however, was lower than that in soil. Concentrations of PAH16 in vegetable were higher than those reported in the literature for other areas. It appears that agricultural soils and vegetables in Tianjin, especially those from the site located immediately next to an urban district and irrigated with wastewater for several decades, are severely contaminated by PAHs. Among the eight types of vegetable studied, the highest concentration of PAHs was found in cauliflower. By average, the concentration of PAH16 in the aerial part of vegetables was 6.5 times higher as that in vegetable root, suggesting that foliar uptake is the primary transfer pathway of PAHs from environment to vegetables.

Use of sequential ASE extraction to evaluate the bioavailability of DDT and its metabolites to wheat roots in soils with various organic carbon contents

An accelerated solvent extraction (ASE) procedure using water, n-hexane and a mixture of n-hexane and acetone as solvents in sequence was developed and tested to evaluate the bioavailability of DDT and its metabolites including p,p'-DDT, o,p'-DDT, p,p'-DDE, and p,p'-DDD (SigmaDDTs) to wheat uptake from soils characterized by varied organic carbon contents. Results indicated that the extractability of SigmaDDTs with water was enhanced considerably in the presence of water soluble organic carbon (WSOC), while the amount of SigmaDDTs extracted with n-hexane was negatively correlated to the content of water insoluble organic carbon (WIOC). The interaction between SigmaDDTs and WIOC also reduced the bioavailability of the pesticides to wheat roots during uptake. There was a good positive correlation between the amount of SigmaDDTs extracted by n-hexane and the amount of SigmaDDTs accumulated in wheat roots, suggesting some potential for the use of the n-hexane ASE-extracted fraction as an indicator of SigmaDDTs' bioavailability to plant uptake. As such, the three sequentially extracted fractions may be viewed as representing the mobile, bioavailable, and fixed pools of SigmaDDTs in the soil.

Level and distribution of DDT in surface soils from Tianjin, China

One hundred and eighty eight surface soil samples were collected from the Tianjin area to study the contamination of DDT and its metabolites. Measurements were taken for p,p'-DDE, p,p'-DDD, p,p'-DDT, o,p'-DDE, o,p'-DDD and o,p'-DDT for all samples. The results indicated that p,p'-DDT and p,p'-DDE were the predominant contaminant compounds in the surface soil samples, with mean concentrations of 27.5 and 18.8 ng g(-1) respectively. No significant differences in DDT concentrations were found between the soils from wastewater treated irrigated areas and other areas, suggesting that wastewater irrigation is not an important source of DDT in the area. However, the spatial distribution of soil DDTs levels in the area did correlate well with early direct application rates of pesticides. In addition, both pH level and organic carbon content are also known factors affecting the level of DDT and its metabolites. Although it was assumed that the use of these chemicals was banned in the early 1980s, the current concentration levels appear to be too high to be mere residuals after 20 years degradation.

The effect of pH, ion strength and reactant content on the complexation of Cu2+ by various natural organic ligands from water and soil in Hong Kong

The complexation constants for copper associated with different natural organic ligands, including dissolved organic carbon (DOC) extracted from water, water soluble organic carbon (WSOC), fulvic acid (FA) and humic acid (HA) from soil, were determined and then compared based on discrete single site model. Both ion-selective electrode (ISE) and anodic stripping voltammetry were used to determine the content of free copper ions, while the relative number of complexation sites was estimated using a fluorescence quenching (FQ) at the same time. ISE proved to be the most applicable technique when the concentration of copper was above 10(-7) moll(-1). The logk values for two WSOC sample sites (Song Ziyuan and Xin Niangtan) were 4.64 and 4.66; higher than both the DOC and HA values yet lower than the FA values, which were unusually high due to unavoidable pollution from the cation exchange resin used during the purification process. Binding affinities between the copper ions and the organic ligands obtained from streams in Yong Wei (DOC) and Song Ziyuan (WSOC) were influenced by pH, ion strength, and reactant concentration. Values for logk increased with increases in pH (ion strength of 0.1 N). At pH 4, the logk values decreased with increases in the supporting electrolyte concentration and total copper ion additions.

Low-cost and efficient coupling technique using reflowed sol-gel microlens

In this paper, we present a novel reflow technique for the fabrication of an elliptical microlens array in sol-gel glass. The fabricated refractive microlens array has a very smooth surface, and structural and dimensional conformity with the designed parameters. It is shown that the microlens array can provide high coupling efficiency of a laser diode to a single mode fiber, and relax the lateral and axial misalignment tolerance. The microlens coupling technique has the advantages of low coupling loss, large misalignment tolerances, and small package volume.

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.

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.

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.

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.

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.

Modeling the fate of benzo[a]pyrene in the wastewater-irrigated areas of Tianjin with a fugacity model

A Level III fugacity model was applied to characterize the transfer processes and environmental fate of benzo[a]pyrene in wastewater-irrigated areas of Tianjin, China. The physical-chemical properties and transfer parameters of benzo[a]pyrene were used in the model and the concentration distribution of benzo[a]pyrene in sediment, soil, water, air, fish, and crop compartments, as well as transfer fluxes across the compartments, were then derived under steady-state assumptions. The calculated results were compared with monitoring data for air, soil, water, and sediment collected from the literature. The results indicate that there was generally good agreement and the differences were within an order of magnitude for air, soil, and sediment. The concentration of benzo[a]pyrene in the ambient air in the area was very low with a majority present sorbed to aerosol. In the water compartment, approximately 70% of benzo[a]pyrene dissolved in water phase. Relatively high concentrations of the compound were found in the soil and sediment, with the soil serving as the dominant sink in the area. Benzo[a]pyrene, with a slow metabolic rate, was found to accumulate in fish in the area.

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.

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.

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.

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.

[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.

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.

A comparison of the fragment constant and molecular connectivity indices models for normalized sorption coefficient estimation

Fragment constant and molecular connectivity indices models were developed based on the measured normalized sorption coefficient values of 592 chemicals. The two models were compared for precision in terms of their adjusted coefficients of determination and their mean residuals. Model robustness was evaluated and compared using jackknifed mean residuals derived from class-by-class deletion. Results indicated that a relatively greater precision could be achieved using the fragment constant approach compared with the molecular connectivity indices model. The adjusted coefficients of determination of the two models were 0.965 and 0.765 and the mean residuals were 0.366 and 0.440, respectively. Although there were a relatively small number of independent variables involved, the robustness of the molecular connectivity indices model was greater than that of the fragment constant method as far as extrapolation among chemical classes is concerned.

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.

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.

[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.

[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.

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.