Selective binding of polychlorinated biphenyl congeners by a monoclonal antibody: analysis by kinetic exclusion fluorescence immunoassay

A previously described monoclonal antibody, S2B1, was highly selective for coplanar (non-ortho-chlorinated) PCB congeners in enzyme immunoassays that measured binding at equilibrium. In the present study, kinetic exclusion fluoroimmunoassay (KinExA) was used to determine the dissociation constants (Kd) and on and off rates (k(on), k(off)) for binding of various PCB congeners to affinity-purified S2B1 IgG and Fab fragments in solution. This method revealed that mono- and di-ortho-chlorinated PCBs were bound by S2B1, but the on rates were slower, and the off rates faster by 6-60-fold, than with congeners that had no ortho chlorines. Although the sensitivity of immunoassays may be improved by using competing haptens that S2B1 binds more weakly than the parent PCB, the KinExA results demonstrate that congener specificity is an intrinsic property of S2B1 and does not require weaker binding haptens. KinExA also provided new information on the percentage of active binding sites, valence, and effects of buffer, solvent, and biotinylation on S2B1. The advantages and drawbacks of KinExA for measuring antibody-ligand binding are described.     

Comparative analysis of polychlorinated biphenyl decomposition processes in air or argon (+oxygen) thermal plasma

Thermal plasmas may solve one of the biggest toxic waste disposal problems. The disposal of polychlorinated biphenyls (PCBs) is a long standing problem which will get worse in the coming years, when 180000 tons of PCB-containing wastes are expected to accumulate in Europe (Hot ions break down toxic chemicals, New Scientist, 16 April 1987, p. 24.). The combustion of PCBs in ordinary incinerators (at temperature T approximately 1100 K, as measured near the inner wall of the combustion chamber (European Parliament and Council Directive on Incineration of Waste (COM/99/330), Europe energy, 543, Sept. 17, 1999, 1-23.)) can cause more problems than it solves, because highly toxic dioxins and dibenzofurans are formed if the combustion temperature is too low (T<1400 K). The paper presents a thermodynamic consideration and comparative analysis of PCB decomposition processes in air or argon (+oxygen) thermal plasmas.     

Characterization and distribution of polycyclic aromatic hydrocarbon in surface water and sediment from Qiantang River, China

The spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) has been investigated in Qiantang River, an important drinking water resource in Yangzi River Delta, China. A total of 218 samples, including 180 water and 38 sediment samples were collected in January, April, July and October, 2005. The concentrations of total PAHs in water ranged from 70.3 to 1844.4ng/L with the mean value of 283.3ng/L, which were predominated by two- and three-ring PAHs. The concentration of total 15 PAHs in sediment ranges from 91.3 to 614.4ng/g dry weight with the mean value of 313.1ng/g dry weight, and three- and four-ring PAHs were dominant species. The ratios of AN/(AN+Phen) and Flur/(Flur+Pye) were calculated to evaluate the possible sources of PAHs. These ratios reflected a pattern of petrogenic input of PAHs in Qiantang River. The contents of PAHs in city zones were much higher than those in rural areas. It may be concluded that the urbanization and industrialization are causing some negative effect on the drinking water resource. As a drinking water resource, there existed certain potential health risks to drinking water consumers and organism in Qiantang River Basin.     

Influence of initial dopant distribution in fiber core on refractive index distribution of thermally expanded core fibers

We investigate the process of dopant diffusion of a thermally expanded core fiber by solving the corresponding diffusion equation using the explicit finite-difference method. We compare our numerical solution with analytical solution of diffusion equation for two different initial dopant concentrations in the core. The conclusions reached provide a guideline for the accurate modeling of dopant diffusion of thermally expanded core fibers, which is important for the prediction of the mode field enlargement.     

Radiation dose in the high background radiation area in Kerala, India

A systematic radiological survey has been carried out in the region of high-background radiation area in Kollam district of Kerala to define the natural gamma-radiation levels. One hundred and forty seven soil samples from high-background radiation areas and five samples from normal background region were collected as per standard sampling procedures and were analysed for (238)U, (232)Th and (40)K by gamma-ray spectroscopy. External gamma dose rates at all sampling locations were also measured using a survey meter. The activities of (238)U, (232)Th and (40)K was found to vary from 17 to 3081 Bq kg(-1), 54 to 11976 Bq kg(-1) and BDL (67.4 Bq kg(-1)) to 216 Bq kg(-1), respectively, in the study area. Such heterogeneous distribution of radionuclides in the region may be attributed to the deposition phenomenon of beach sand soil in the region. Radium equivalent activities were found high in several locations. External gamma dose rates estimated from the levels of radionuclides in soil had a range from 49 to 9244 nGy h(-1). The result of gamma dose rate measured at the sampling sites using survey meter showed an excellent correlation with dose rates computed from the natural radionuclides estimated from the soil samples.     

Quantitative enzyme-linked immunosorbent assay for determination of polychlorinated biphenyls in environmental soil and sediment samples

An enzyme-linked immunosorbent assay (ELISA) for the quantitative determination of Aroclors 1242, 1248, 1254, and 1260 in soil and sediments was developed and its performance compared with that of gas chromatography (GC). The detection limits for Aroclors 1242 and 1248 in soil are 10.5 and 9 ng/g, respectively. The assay linear dynamic range is 50-1333 ng/g. Cross-reactivity of the assay with 37 structurally related potential cocontaminants in environmental soil samples was examined; none of the chlorinated anisoles, benzenes, or phenols exhibited >3% cross-reactivity, with <0.1% cross-reactivity being the norm. Soil spike recoveries of 107% and 104% were obtained for Aroclors 1242 and 1248, respectively, for a spike level of 5 mg/kg, with corresponding relative standard deviations of 14% and 17%. One hundred forty-eight environmental soil, sediment, and paper pulp samples, obtained from two EPA listed Superfund sites, were analyzed by ELISA and standard GC methods. Samples were extracted for ELISA analysis by shaking with methanol. Additional extractions of the same samples were performed either with supercritical carbon dioxide or by Soxhlet extraction with methanol. ELISA results for both the supercritical fluid and the Soxhlet extracts were in close agreement with the GC results, while the ELISA results for the methanol shake extracts were not. The data for the environmental samples demonstrated the capability of the ELISA to provide accurate results and reinforced the dependence of any detection method, including ELISA, on appropriate extraction procedures.     

Background radiation and individual dosimetry in the costal area of Tamil Nadu, India

South coast of India is known as the high-level background radiation area (HBRA) mainly due to beach sands that contain natural radionuclides as components of the mineral monazite. The rich deposit of monazite is unevenly distributed along the coastal belt of Tamil Nadu and Kerala. An HBRA site that laid in 2×7 m along the sea was found in the beach of Chinnavillai, Tamil Nadu, where the maximum ambient dose equivalent reached as high as 162.7 mSv y(-1). From the sands collected at the HBRA spot, the high-purity germanium semi-conductor detector identified six nuclides of thorium series, four nuclides of uranium series and two nuclides belonging to actinium series. The highest radioactivity observed was 43.7 Bq g(-1) of Th-228. The individual dose of five inhabitants in Chinnavillai, as measured by the radiophotoluminescence glass dosimetry system, demonstrated the average dose of 7.17 mSv y(-1) ranging from 2.79 to 14.17 mSv y(-1).     

Transfer factor of the radionuclides in food crops from high-background radiation area of south west India

It is necessary to obtain the transfer factor (TF) of long-lived radionuclides because soil type and vegetation can affect TF. We studied the food crops commonly consumed by the general public of Kanyakumari district of south India. The main focus was on rice, fruits, vegetables and tapioca because the consumption of these is high. The soil to rice TF for the radionuclides, (226)Ra, (232)Th, (238)U and (40) K are 8.8×10(-2), 14.2×10(-2), 5.8×10(-2) and 6.3×10(-2), respectively. The TF of tapioca for (226)Ra, (232)Th, (238)U and (40) K are 6.2×10(-2) , 11×10(-2), 1.9×10(-2) and 8.9×10(-2), respectively. For fruits and vegetables, the TFs are low. In the majority of the crops the non-edible parts accumulate more radionuclides than the edible parts.     

Chemical signatures of the Anthropocene in the Clyde estuary, UK: sediment-hosted Pb, (207/206)Pb, total petroleum hydrocarbon, polyaromatic hydrocarbon and polychlorinated biphenyl pollution records

The sediment concentrations of total petroleum hydrocarbons (TPHs), polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), Pb and (207/206)Pb isotope ratios were measured in seven cores from the middle Clyde estuary (Scotland, UK) with an aim of tracking the late Anthropocene. Concentrations of TPHs ranged from 34 to 4386 mg kg(-1), total PAHs from 19 to 16,163 μg kg(-1) and total PCBs between less than 4.3 to 1217 μg kg(-1). Inventories, distributions and isomeric ratios of the organic pollutants were used to reconstruct pollutant histories. Pre-Industrial Revolution and modern non-polluted sediments were characterized by low TPH and PAH values as well as high relative abundance of biogenic-sourced phenanthrene and naphthalene. The increasing industrialization of the Clyde gave rise to elevated PAH concentrations and PAH isomeric ratios characteristic of both grass/wood/coal and petroleum and combustion (specifically petroleum combustion). Overall, PAHs had the longest history of any of the organic contaminants. Increasing TPH concentrations and a concomitant decline in PAHs mirrored the lessening of coal use and increasing reliance on petroleum fuels from about the 1950s. Thereafter, declining hydrocarbon pollution was followed by the onset (1950s), peak (1965-1977) and decline (post-1980s) in total PCB concentrations. Lead concentrations ranged from 6 to 631 mg kg(-1), while (207/206)Pb isotope ratios spanned 0.838-0.876, indicative of various proportions of 'background', British ore/coal and Broken Hill type petrol/industrial lead. A chronology was established using published Pb isotope data for aerosol-derived Pb and applied to the cores.     

Surface area, pore size distribution and microstructure of vacuum getter

An effective getter is necessary in vacuum technology. In order to obtain the adsorption mechanism of the getter, its microstructure information must be studied. Surface area, pore size distribution and microstructure of vacuum getter were studied with XRD, SEM and N₂ adsorption technique.Vacuum getter is composed of the different proportions of PdO and Ag₂O. The crystalline size of 3^# vacuum getter that includes W₂AgO = 22% and W_PdO = 78% is the maximum among all the vacuum getters. SEM images showed that vacuum getters expose a large number of nanometer-size pores. The adsorption isotherms of the vacuum getters are typical of type Ⅳ, characteristic of mesoporous material, and a type H₂ hysteresis loop is observed. Langmuir model describes N₂ adsorption at low pressure region. At the medium pressure, N₂ adsorption can be modeled by BET model. The pore size distributions of the vacuum getters are calculated by applying BJH method to the adsorption branch of N₂ isotherms at 77 K. With percentage of Ag₂O elevation, Langmuir surface area, BET specific surface area, the adsorption capacity and the pore volume become larger. But the average pore diameter becomes smaller. However, above Ag₂O content of 22%, an inverse behavior is observed. 3^# vacuum getter has the highest surface area and pore volume among all the vacuum getters. The experimental results and related analysis can be adopted in the later design of the vacuum tank.     

Cadmium distribution in sediment profiles of the six main rivers in southern Taiwan

Dynamic cadmium distribution has been studied in six main rivers flowing through the largest, most highly developed and polluted area of southern Taiwan. Sediment profile samples were also analyzed for Cu, Cr, Zn, Ni, Pb, Co, Mn, Fe, carbonates, Mn-oxides, Fe-oxides and organic matter in order to characterize the geochemical environment and to identify the pollutant sources. Higher Cd concentrations (about 3.5 mg/kg) at depths of 0-10 cm have been detected in the samples of Yenshui, Ell-ren and Potzu rivers, associated to the history of industrial activity in their catchments. According to the linear correlation coefficient (r) between Cd and the geochemical components, carbonates are the primary Cd binding phase in the Ell-ren river (r=0.85), and Cd comes from the same pollutant sources of those containing Cr, Ni, Cu and Zn (r>0.80). Cadmium concentration in the Potzu and Peikang river sediments is probably due to waste deposits rich in Cr and Cu (0.54相似文献   

Electrodialytic extraction of Cd and Cu from sediment from Sisimiut Harbour, Greenland

A previous study showed that the sediment of Sisimiut Harbour, Greenland is polluted with Cu and Cd to an extent where toxicological effects must be expected. This study was aimed at evaluating the possibility for removing Cu and Cd from this sediment by an electrodialytic method and also to evaluate the removal rate of the two heavy metals. The sediment was suspended in distilled water during application of current. Both heavy metals were removed successfully. The Cu concentration was reduced from 97 to 16mg/kg and the Cd concentration was reduced from 0.55 to 0.03mg/kg after 28 days with an applied current density of 1.2mAcm(-2). However, it was seen that the removal rate decreased considerably after 3 days with an applied current density of 0.5mAcm(-2) and the major part of the two heavy metals was removed during the first 3 days (the Cu concentration was reduced with 74% and the Cd concentration with 80%). Thus a large reduction in concentrations can be obtained relatively fast. During the process of electrodialytic treatment the sediment suspension is acidified and reaches pH 2 after about 3 days (with 0.5mAcm(-2)), where it stabilizes. A comparison with chemical extraction in HNO(3) at about the same pH showed that 50-70% more Cu and 11% more Cd was removed during the electrodialytic treatment.     

Impact assessment of chromite mining on groundwater through simulation modeling study in Sukinda chromite mining area, Orissa, India

The pre-Cambrian chromites ore deposits in Sukinda valley, Jajpur District, Orissa, India, are well known for chromite ore deposits. The exploitation of the ore is carried out through open cast mining method since the last few decades. In the process, the overburden and ore dumps are stored on ground surface, where leaching of chromite and other toxic element takes place particularly during monsoon seasons. This leachate may cause threat to groundwater in the vicinity. An integrated approach has been adopted to evaluate possibility of pollution due to mine seepage and leachate migration on groundwater regime. The approach involves geophysical, hydrogeological, hydro-chemical and aquifer modeling studies. The investigation has the significance as many habitats surround the mining area facing groundwater problems.     

Distribution of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) and dioxin-like polychlorinated biphenyls (dioxin-like PCBs) in the soil in a typical area of eastern China

The distribution and concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dioxin-like PCBs, also called co-PCBs) in a typical area of eastern China were evaluated by analysis of 21 soil and 6 sediment samples. The range of WHO-TEQ values for the PCDD/Fs and dioxin-like PCBs in 17 soil samples representing the background investigation in the study area was 0.017-5.04 pg g(-1) (dry weight, dw), with a mean value 0.967(+/-1.361)pg g(-1) and medium value 0.348 pg g(-1), which indicates that the levels of PCDD/Fs and dioxin-like PCBs over the major part of this district were low. However, the WHO-TEQ values (6.52-16.7 pg g(-1) dw) for PCDD/Fs and dioxin-like PCBs in soil samples to the leeward of a known contaminated disassembly industrial park were much higher than that of the background investigation, and the levels of sediment samples downstream of this area were in the range 2.25-34.6 pg g(-1) (dw). The levels of WHO-TEQ in soil and sediment samples decreased with an increase in distance from the researched pollution source. The principal component analysis demonstrated that the PCDD/Fs and dioxin-like PCBs in major part of contaminated sediment and soil samples derived from the correlative matrix. Yet the different distribution patterns of them in part of sediment samples strongly indicate that other potential sources may be exist, further researches should be done to get more information about the sources and the distributions of the PCDD/Fs and PCBs.