Trace element distribution in the superficial deposits of Northern Derbyshire,England

In an area of marginal farming, trace element distribution associated with lead, fluorite and baryte mineralization is important to the farmer because of the high infertility rate of the livestock and contamination of plant produce leading to the subsequent failure of the farming economy. Therefore sampling of superficial sediments was undertaken over the mineralized Carboniferous Limestone of North Derbyshire above the medieval lead and the modern fluorite workings. Twenty-seven elements were analyzed using emission spectrophotometry and subsequently compared with the geochemistry of the underlying bedrock. Discrepancies which occur are attributed to the glacial and periglacial action during the Wolstonian and Devensian glacial episodes.     

Micromorphology and ultrastructure of Caribbean sclerosponges

Fine structural analysis of living tissue of the sclerosponges Ceratoporella nicholsoni (Hickson) and Stromatospongia norae Hartman, collected near Discovery Bay, Jamaica, between 1984 and 1986, was carried out using transmission and scanning electron microscopy (TEM and SEM). The thick dermal membrane of these sponges is covered by exopinacocytes having a T shape in sections perpendicular to the surface. A dense, complex glycocalyx is produced at the surface of these cells. Choanocyte chambers are diplodal and unusually small. The inhalant and exhalant canals of both species are characterized by the presence of valvules, made by transverse lamellipodial processes of the endopinacocytes lining them. An abundant and diversified bacterial community occupies almost 20% of the mesohyl. A single layer of active basopinacocytes lines the mesohyl at the interface between the living tissue and the aragonitic skeleton. Basopinacocytes are presumed to be precursors of the irregular fibrillar organic matrix found in the aragonitic skeleton. Sclerocytes and spongocytes are abundant in the vicinity of the siliceous spicules. Typical lophocytes releasing smooth collagen fibrils are common in the dermal membrane as well as in the choanosome where they can be grouped in bundles. Uniquely, C. nicholsoni elaborates rough intercellular fibrils characterized by periodically spaced thickenings. The endolithic algae Ostreobium sp. is present in the most apical zones of the aragonitic skeleton, but does not seem to interfere with its development. The striking micromorphological resemblances between both species are discussed and compared to demosponges.Contribution no. 472 from the Discovery Bay Marine Laboratory, University of the West Indies, Discovery Bay, Jamaica, West Indies     

The role of echinoderms as bioindicators of seawater pollution: A case study from patraicos and corinthiacos Gulf,N. Peloponnesus,Greece

To determine the role of echinoderms as bioindicators of seawater pollution we collected sea‐water and urchin samples from two sites in N. Peloponnesus, Greece. One site was in Patraicos gulf (Patras) and was influenced by point source pollution (urban sewage outfalls) while the second was in Korinthiacos gulf (Akoli) with no evident habitat pollution.

Three heavy metals (copper, nickel and zinc) have been measured in the gonads of two edible species of echinoderms, Arbacia lixula and Paracentrotus lividus.

Statistical treatment of the results showed statistically significant differences in bioaccu‐mulation related to the dry‐weight of gonads, to species, to sex of echinoderms, to season of sampling and to sampling station.

The concentrations of zinc were higher than those of Ni and Cu at in both sampling sites.

Microbiological analysis showed that contamination of the urchins was correlated to that of the surrounding seawater.

Finally both sampling sites seems to be influenced, directly or indirectly, by heavy metal and bacterial habitat pollution.     

Toxic equivalency factor approach for risk assessment of polycyclic aromatic hydrocarbons

The toxic equivalency factor (TEF) method has been developed to evaluate structurally related compounds, sharing a common mechanism of action. Because certain polycyclic aromatic hydrocarbons (PAHs) appear to fit this requirement and are ubiquitous environmental contaminants, these compounds are TEF candidates. Toxicity is often expressed relative to benzo[a]pyrene (BaP), the reference standard (e.g., TEF = EC50_BaP/EC50_PAH). BaP‐like toxicity or toxic equivalents (TEQs) can then be calculated: TEQ = S(PAH _i × TEF _i ), where PAH _i and TEF _i are the concentration and TEF, respectively, for individual PAH congeners. Representative TEFs for PAHs were compiled from studies measuring carcinogenic potency and surrogate biomarkers. This review examines the application of TEFs to PAHs with established criteria (i.e., demonstrated need, defined chemical grouping, broad toxicological database, endpoint consistency, additivity, common mechanism of action, consensus). Although all criteria are not satisfied (e.g., endpoint inconsistency, nonadditivity) and more rigorous validation studies are needed, the TEF method is useful when limitations are recognized. Refinements of the method might include incorporation of pharmacokinetic factors and segregation of TEFs derived from mammalian vs. nonmammalian systems to increase endopoint consistency. Probabilistic analysis may also prove useful to assess the range of TEF values reported both within and between human health and ecological risk assessments.     

Placental mosaicism in a case of 46,XY, −22, +t(22;22)(p11;q11) or i(22q) diagnosed at amniocentesis

46,XY, −22,+t(22;22)(p11;q11) or i(22q) was diagnosed in 15/15 cells from two cultures from the amniotic fluid culture of a 31-year-old patient whose fetus demonstrated cystic hygroma on ultrasound. Cytogenetic studies performed on fetal skin from the abortus revealed the same karyotype as that seen on amniocentesis, but the placenta demonstrated a 46,XY,46,XY, −22,+t(22;22) or i(22q) mosaicism, with 65 per cent of the cells being 46,XY. This case provides an example of placental mosaicism for a normal male karyotype, while the fetus demonstrated non-mosaic trisomy 22.     

Amniotic fluid levels of human chorionic gonadotropin and its alpha and beta subunits in second-trimester chromosomally abnormal pregnancies

Amniotic fluid from 135 pregnancies was assayed for human chorionic gonadotropin (hCG) and its free alpha (ahCG) and free beta (bhCG) subunits. Forty-six chromosomally abnormal pregnancies between 14 and 20 weeks' gestation were matched with 89 chromosomally normal samples. Compared with controls, trisomy 21 pregnancies exhibited significantly elevated levels of all three peptides, whereas trisomy 18 gestations gave rise only to significant elevation of ahCG. Female fetuses in both the trisomy 21 and trisomy 18 pregnancies provided significantly elevated levels of hCG and bhCG compared to their male counterparts. On converting the values to multiples of the median, it was determined that 6 of 7 trisomy 18 samples had abnormally elevated alpha/beta ratios, as did 6 of 21 Down's syndrome pregnancies. Further, 11 of 21 trisomy 21 gestations had abnormal amniotic fluid hCG levels. Using only ahCG, bhCG and their ratio, a 61 per cent sensitivity was found for these trisomies, with a 96 per cent specificity.     

安全科学基本理论规律研究

通过对事物发展过程中的安全与危险的矛盾运动过程分析,抽象出一些基本概念和事故从孕育到发生发展及结束和后效阶段的基本特征,并对部分事例进行了分析。提出了安全科学的统一规律——安全流变与突变论,并初步建立了安全流变论的数学模型