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971.
Bivalves are often used as sentinel organisms in monitoring programmes for trace organic contaminants. the animal's physiological state may be important in interpreting trends in contaminant body burden. Simultaneous evaluation of physiological state and organic contaminant concentration in bivalves typically involves removal of a lipid-rich cross-section of the body mass for histopathological and/or gonadal analysis.
In this study, the bias introduced by this technique in the final trace organic concentrations, e.g. of polynuclear aromatic hydrocarbons, chlorinated pesticides and polychlorinated biphenyls, are evaluated on five different size groups of oysters. As a test case, we evaluated the use of this method in the NOAA's Status & Trends Mussel Watch (NS&T) Programme. the average biases introduced by this technique in the final trace organic concentrations in Gulf of Mexico oysters have been increasing since 1986 as a consequence of a continuous decrease in the size of the individuals sampled. 相似文献
In this study, the bias introduced by this technique in the final trace organic concentrations, e.g. of polynuclear aromatic hydrocarbons, chlorinated pesticides and polychlorinated biphenyls, are evaluated on five different size groups of oysters. As a test case, we evaluated the use of this method in the NOAA's Status & Trends Mussel Watch (NS&T) Programme. the average biases introduced by this technique in the final trace organic concentrations in Gulf of Mexico oysters have been increasing since 1986 as a consequence of a continuous decrease in the size of the individuals sampled. 相似文献
972.
973.
A study of the seasonal dynamics of cell proliferation in the digestive tract epithelia of the mussel Crenomytilus grayanus (Bivalvia) collected in the Sea of Japan between 1971 and 1984 revealed two opposite states so far unknown for marine molluscan tissues: proliferative resting in winter and a following outburst of cell division in spring. In winter and early spring (at water temperatures below or near 0°C), mitotic figures in the lining epithelia of labial palps and intestine strongly reduced in number and later almost disappeared (February-March); DNA-synthesizing cells in these epithelia on thymidine radioautographs became sparse and only a restricted number of new cells entered the cell cycle. A proliferation block was relieved at the beginning of April (at a temperature of 2 to 4°C): an initiation of a many-fold increase in the mitotic index and some increase in the 3H-T-labelled nuclei index and their advance to the maximum in late April to May (up to more than 0.2 and 5 to 6%, accordingly) were found. In late spring (at temperatures of 5 to 10°C), a striking rise in the number of cells entering the cell cycle was observed with a probable acceleration of the cycle proper. Both seasonal states of cell proliferation — a deep depression and outburst, established in the winter-spring period are interpreted as essential events in the life cycle of the mussel studied. 相似文献
974.
Nanocrystals were prepared by acid hydrolysis of bacterial cellulose microfibrils. These were topochemically trimethylsilylated, in an attempt to reduce their hydrophilicity. Composites were made by dispersing either native or silylated crystals in cellulose acetatebutyrate matrixes and solution casting of the dispersions. Particles were characterized by transmission electron microscopy. The composites were characterized by differential scanning calorimetry and dynamic mechanical analysis. The unmodified cellulose crystals exhibited better reinforcement characteristics than the trimethylsilated crystals. 相似文献
975.
Marine Biology - Little is known about the effect of commercial rockweed (Ascophyllum nodosum) harvest on intertidal community structure, and on interactions among species. Using predator-exclusion... 相似文献
976.
977.
Dennis J. Paustenbach Tibor T. Sarlos Brent L. Finley David A. Jeffrey Michael J. Ungs 《Chemosphere》1991,23(11-12)
Conservative models were used to estimate the airborne concentrations of 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) vapor and particulates originating from soil containing 100 ppb TCDD. The upper-bound estimates were 3.25 pg/m3 of airborne TCDD vapor on-site and 0.51 pg/m3 for TCDD vapor 100 meters downwind. The TCDD air concentration on-site due to suspended particulate is estimated to be 1.4 pg/m3, based on a TSP level of 0.07 mg/m3. Assuming 70 years of continuous exposure to these concentrations, the upper-bound cancer risks determined from the Jury model were estimated to be 9.4 × 10−6 to 1.1 × 10−4 and 1.5 × 10−6 to 1.7 × 10−5 for inhalation of on- and off-site vapor, respectively, and 4.1 × 10−6 to 4.6 × 10−5 for dust inhalation. Since few sites have average soil concentrations as high as 100 ppb TCDD, this worst-case analysis indicates that inhalation will rarely, if ever, be a significant route of exposure to TCDD-contaminated soil. Experimental results support this claim and point to much lower risk estimates (8.4 × 10−9 to 9.9 × 10−8), suggesting that the parameters used in the Jury model are likely to overestimate the actual airborne levels of TCDD at contaminated sites. 相似文献
978.
Martha E. Rode Michael T. Mennuti Rose M. Giardine Elaine H. Zackai Deborah A. Driscoll 《黑龙江环境通报》2001,21(7):575-580
We report the mid-trimester prenatal diagnosis of Neu–Laxova syndrome (NLS) in two at risk families utilizing serial sonographic examinations. Ultrasound and pathologic findings from seven affected pregnancies, the largest case series of NLS to date, are presented. One fetus had anencephaly and incomplete rachischisis, an anomaly that has not been previously reported in association with NLS. Ultrasonographic detection of severe intrauterine growth restriction (IUGR), abnormally postured limbs, microcephaly, and edema allowed prenatal diagnosis of NLS in five of these at risk pregnancies during the mid-trimester. Growth curves derived from serial sonograms reveal abnormalities of all standard biometric measurements. The growth discrepancy was most pronounced in the measurements of the biparietal diameter, which were consistently less than two standard deviations below the mean across all gestational ages. This case series confirms that aberrant growth and anomalies may be detected sufficiently early in gestation to permit prenatal diagnosis of NLS. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
979.
Janus T Kirkeby Harpa Birgisdottir Trine Lund Hansen Thomas H Christensen Gurbakhash Singh Bhander Michael Hauschild 《Waste management & research》2006,24(1):16-26
A new computer based life cycle assessment model (EASEWASTE) was used to evaluate a municipal solid waste system with the purpose of identifying environmental benefits and disadvantages by anaerobic digestion of source-separated household waste and incineration. The most important processes that were included in the study are optical sorting and pre-treatment, anaerobic digestion with heat and power recovery, incineration with heat and power recovery, use of digested biomass on arable soils and finally, an estimated surplus consumption of plastic in order to achieve a higher quality and quantity of organic waste to the biogas plant. Results showed that there were no significant differences in most of the assessed environmental impacts for the two scenarios. However, the use of digested biomass may cause a potential toxicity impact on human health due to the heavy metal content of the organic waste. A sensitivity analysis showed that the results are sensitive to the energy recovery efficiencies, to the extra plastic consumption for waste bags and to the content of heavy metals in the waste. A model such as EASEWASTE is very suitable for evaluating the overall environmental consequences of different waste management strategies and technologies, and can be used for most waste material fractions existing in household waste. 相似文献
980.