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341.
Low bone density and renal dysfunction following environmental cadmium exposure in China 总被引:1,自引:0,他引:1
This paper presents the main findings of a study on health effects of environmental cadmium pollution in China, performed in 1998, i.e. approximately 25 years after the first warnings of such effects were published in Ambio. Forearm bone mineral density (BMD) and renal dysfunction were assessed in population groups exposed to cadmium via rice. Decreased BMD was found in postmenopausal women with elevated urinary cadmium (CdU) or cadmium in blood (CdB) and among men with elevated CdB. Also, clear and statistically significant dose-effect and dose-response relationships were found between CdB or CdU and renal dysfunction (increased excretion of retinol-binding protein). This is the first report of bone effects among Cd-exposed population groups in Asia outside Japan. The report is also of interest since it demonstrates that bone effects, a comparatively severe adverse health effect of Cd, in combination with renal dysfunction, still occurs in environmentally exposed population groups in Asia. Recent reports on bone effects in Cd-exposed population groups in Europe are discussed. 相似文献
342.
An emulsion stabilized by colloidal suspensions of finely divided solids is known as a Pickering emulsion. The potential for polychlorinated biphenyls (PCBs) to form Pickering emulsions ex situ when in contact with powdered solids, such as clays and metal oxides, is investigated here. Bentonite, iron oxide and magnesium oxide dispersions proved to be robust Pickering emulsion stabilizers, whereas manganese oxide dispersions were not. Batch experiments revealed that emulsions can be formed using a moderately low energy input and can be stabilized with solid concentrations as low as 0.5 wt.%. For the base conditions (volumetric oil fraction (phi(oil))=30 vol.%; solid concentration (chi)=2 wt.%), the formed emulsions were indefinitely stable and the initial average droplet diameters varied from 80 to 258 mum, depending on the solid used in the colloidal dispersion. The average droplet size varied at early time, but for most conditions stabilized to a steady-state value 1 week after preparation. The effect of Ostwald ripening was limited. At greater than 0.5 wt.% concentration, the efficiency of the solid dispersion as a stabilizer was dependant on the volumetric oil fraction but not on the solid concentration. Generally, systems with volumetric oil fractions outside of the 20-70 vol.% range were unstable. The emulsions' droplet stability, average droplet size and size distribution were observed to vary as a function of the amount of energy provided to the system, the volumetric oil fraction, and the concentration of the solid in the aqueous dispersion. It is hypothesized that drilling through fractured rock in the immediate vicinity of dense, non-aqueous phase liquid (DNAPL) PCBs may provide both the energy and solid material necessary to form Pickering emulsions. 相似文献
343.
Jason H. Peterson Bernard D. Roitberg J. H. Peterson 《Behavioral ecology and sociobiology》2006,59(5):589-596
Fisher's theoretical prediction of equal investment in each sex for a panmictic population (The genetical theory of natural selection. Clarendon, Oxford, 1930) can be altered by a number of factors. For example, the sex ratio theory predicts variation in
equal investment in each sex when the maternal fitness gains from increased investment differ between sexes. Changing sex
allocation because of changing payoffs may result from different ecological situations, such as foraging conditions. We investigated
the impact of foraging travel cost on relative investment in sons vs daughters. Field studies were carried out with the central-place-foraging
leafcutter bee Megachile rotundata (Fabricius), which has smaller males than females. Therefore, less investment is required to produce a viable son compared
with a daughter. We found that with increased flight distance to resources, females produced a greater proportion of sons.
Females also invested fewer resources in individual sons and daughters and produced fewer offspring with increased flight
distance. 相似文献
344.
Peggy?Gunkel Estelle?Roth Bernard?FabreEmail author 《Environmental Chemistry Letters》2004,2(2):99-103
We studied copper uptake by maize grown on soils that have been contaminated with CuSO4. In soil the total copper level ranged from 24 to 135 mg kg–1. The copper distribution in soil fractions was assessed by sequential extraction, showing that anthropogenic copper is mainly concentrated in oxides fractions. The copper concentration of maize at the maturity stage reached values from 36.3 to 65.9 mg kg–1 compared to copper levels usually found in non-contaminated crops (5–30 mg kg–1). Here we demonstrate that copper can be accumulated by maize and that copper concentration in maize can be predicted by equations including copper concentration of soil fractions. 相似文献
345.
A national critical loads framework for atmospheric deposition effects assessment: I. Method summary
Timothy C. Strickland George R. Holdren Jr. Paul L. Ringold David Bernard Katie Smythe William Fallon 《Environmental management》1993,17(3):329-334
The United States Environmental Protection Agency (EPA), with the assistance of the US Department of Energy (DOE) and the
National Oceanographic and Atmospheric Administration (NOAA) is examining the utility of a critical loads approach for evaluating
atmospheric pollutant effects on sensitive ecosystems. A critical load has been defined as, “a quantitative estimate of an
exposure to one or more pollutants below which significant harmful effects on specified sensitive elements of the environment
do not occur according to present knowledge.” Working in cooperation with the United Nations Economic Community for Europe’s
(UN-ECE) Long Range Transboundary Air Pollution (LRTAP) Convention, the EPA has developed a flexible, six-step approach for
setting critical loads for a range of ecosystem types. The framework is based on regional population characteristics of the
ecosystem(s) of concern. The six steps of the approach are: (1) selection of ecosystem components, indicators, and characterization
of the resource; (2) definition of functional subregions; (3) characterization of deposition within each of the subregions;
(4) definition of an assessment end point; (5) selection and application of models; and (6) mapping projected ecosystem responses.
The approach allows for variable ecosystem characteristics and data availability. Specific recognition of data and model uncertainties
is an integral part of the process, and the use of multiple models to obtain ranges of critical loads estimates for each ecosystem
component in a region is encouraged. Through this intercomparison process uncertainties in critical loads projections can
be estimated.
The research described in this article has been funded by the US Environmental Protection Agency. This document has been prepared
at the EPA Environmental Research Laboratory in Corvallis, Oregon, through contract #68-C8-0006 with Man Tech Environmental
Technology, Inc. It has been subjected to the agency’s peer and administrative review and approved for publication. Mention
of trade names or commercial products does not constitute endorse ment or recommendation for use. 相似文献
346.
Gertjan de Koning Michele Kellerhals Cisca van Meurs Bernard Witholt 《Journal of Polymers and the Environment》1996,4(4):243-252
Poly[(R)-3-hydroxyalkanoates] (PHAs) are biopolymers stored by bacteria, which are currently receiving much attention because of their potential as renewable and biodegradable plastics. Most well-known representatives are poly[(R)-3-hydroxybutyrate] and its copolymers with 3-hydroxyvalerate, which have been commercialized under the trademark Biopol. In addition to these rigid materials, the elastomeric medium-chain length PHAs (mcl-PHAs) produced by fluorescent Pseudomonads are now emerging. The present review aims to survey the important developments concerning research and application prospects of mcl-PHAs. 相似文献
347.
348.
349.
Françoise Muller Didier Thibaud Françoise Poloce Marie-Christine Gelineau Marguerite Bernard Christine Brochet Christine Millet Jean-Yves Réal Marc Dommergues 《黑龙江环境通报》2002,22(11):1036-1039
In routine obstetrical practice, prior to offering invasive prenatal diagnosis, it is crucial to weigh the risks attendant on amniocentesis against the individual's risk of aneuploidy. We took advantage of a policy of follow-up of patients undergoing Down syndrome maternal serum screening to compare the rates of fetal loss before 24 weeks and of early premature delivery at 24–28 weeks between women who underwent amniocentesis and women who did not. A total of 54 902 patients entered the study, of whom 4039 (7.35%) were lost to follow-up and 387 were excluded because of a severe fetal abnormality. Of the 50 476 remaining patients, 3472 had an amniocentesis whereas 47 004 had not and served as controls. In the amniocentesis group, the fetal loss rate before 24 weeks was 1.12% (95% CI=1.08–1.15) and the 24–28 weeks premature delivery rate was 0.40% (95% CI=0.39–0.41) which was significantly higher than in controls (0.42% with 95% CI 0.41–0.43 and 0.24% with 95% CI 0.23–0.25, respectively). The 0.86% difference in adverse outcome rates between the amniocentesis and control groups may be attributable to amniocentesis and compares favourably with the positive predictive value of maternal serum markers (1.70%) observed in the present study. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
350.