浅析环境监测QC/QA过程的采样环节

对环境监测布点采样中的QC/QA以及由采样引起的误差来源做了简要分析,并对监测采样过程中QC/QA的操作提出了一些设想。     

False-negative prenatal exclusion of Wiskott-Aldrich syndrome by measurement of fetal platelet count and size

The study of the fetal platelet count and size can, according to the literature, be used for the prenatal diagnosis of the Wiskott-Aldrich syndrome (WAS). So far, no affected fetuses have been identified by this method. All pregnancies in which this method had been applied to resulted, as correctly predicted, in the birth of normal children. Here we report on a familial case of WAS where the haematological parameters failed to reveal the affected second child. Hence we assume that the platelet count and size of platelets remain normal in fetuses with WAS to the gestational age of 22 weeks and cannot be used for prenatal diagnosis.     

Submersible observations of the New England Seamounts

Plate tectonics has established the relationship of volcanism to constructional plate margins such as the Mid-Atlantic Ridge, to consuming plate boundaries such as the subduction zones comprising the Pacific “ring of fire,” and to leakage of magma along transform faults like St. Paul's Fracture Zone; however, mid-plate volcanism, which produces many oceanic islands and seamounts, is largely unexplained by plate tectonics. Studies of mid-plate volcanism have been mainly confined to oceanic islands which may be generically different from seamounts. To extend our knowledge of global tectonics and the nature of the underlying mantle source of mid-plate volcanism, we must direct our most advanced techniques to the study of seamounts and their lineaments. Herein we describe the first reported visual observations of the morphology and lithology of volcanoes comprising one such chain—the New England Seamounts.     

低浓度SO2长期暴露下菜豆的生长发育和气孔反应

本研究采用连续搅拌槽反应器系统(CSTR)对菜豆(Phaseolus vulgaris)进行低浓度SO_2长期暴露试验.结果表明,SO_2在植物可见伤害阈值以下抑制了莱豆生长,叶片气孔阻力随SO_2浓度的增加而增加.植物一旦脱离SO_2污染的环境,气孔就恢复到正常水平.切除子叶的菜豆生长明显受抑,但对SO_2敏感性和留子叶菜豆相同.     

Low Genetic Variability in the Hawaiian Monk Seal

The Hawaiian monk seal (   Monachus schauinslandi) is a critically endangered species that has failed to recover from human exploitation despite decades of protection and ongoing management efforts designed to increase population growth. The seals breed at five principal locations in the northwestern Hawaiian islands, and inter-island migration is limited. Genetic variation in this species is expected to be low due to a recent population bottleneck and probable inbreeding within small subpopulations. To test the hypothesis that small population size and strong site fidelity has led to low within-island genetic variability and significant between-island differentiation, we used two independent approaches to quantify genetic variation both within and among the principal subpopulations. Mitochondrial control region and tRNA gene sequences (359 base pairs) were obtained from 50 seals and revealed very low genetic diversity (0.6% variable sites), with no evidence of subpopulation differentiation. Multilocus DNA fingerprints from 22 individuals also indicated low genetic variation in at least some subpopulations (band-sharing values for "unrelated" seals from the same island ranged from 49 to 73%). This method also provided preliminary evidence of population subdivision (  F'_st estimates of 0.20 and 0.13 for two adjacent island pairs). Translocations of seals among islands may therefore have the potential to relieve local inbreeding and possibly to reduce the total amount of variation preserved in the population. Genetic variation is only one of many factors that determine the ability of an endangered species to recover. Maintenance of existing genetic diversity, however, remains an important priority for conservation programs because of the possibility of increased disease resistance in more variable populations and the chance that inbreeding depression may only be manifest under adverse environmental conditions.     

The Reliability of Using Population Viability Analysis for Risk Classification of Species

I examine whether or not it is appropriate to use extinction probabilities generated by population viability analyses, based on best estimates for model parameters, as criteria for listing species in Red Data Book categories as recently proposed by the World Conservation Union. Such extinction probabilities are influenced by how accurately model parameters are estimated and by how accurately the models depict actual population dynamics. I evaluate the effect of uncertainty in parameter estimation through simulations. Simulations based on Steller sea lions were used to evaluate bias and precision in estimates of probability of extinction and to consider the performance of two proposed classification schemes. Extinction time estimates were biased (because of violation of the assumption of stable age distribution) and underestimated the variability of probability of extinction for a given time (primarily because of uncertainty in parameter estimation). Bias and precision in extinction probabilities are important when these probabilities are used to compare the risk of extinction between species. Suggestions are given for population viability analysis techniques that incorporate parameter uncertainty. I conclude that testing classification schemes with simulations using quantitative performance objectives should precede adoption of quantitative listing criteria.