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Selenium is a potent reproductive and teratogenic environmental contaminant and there are concerns over possible reproductive effects of selenium on the Sacramento splittail (Pogonichthys macrolepidotus) population, a threatened species, in California, USA. In this study, the teratogenic effects of selenium were examined in splittail embryos exposed to 0.0, 5.0, and 15.0 mg l(-1) sodium selenite for 48-h at 18.0 degrees C under static conditions, with renewal every 12 h. Embryo development was evaluated daily for abnormalities from initiation of exposure (stage 27) to initiation of exogenous feeding. At the end of evaluation, prelarvae were preserved for histological analysis. There were no significant differences in mortality or hatching success between control and exposed embryos. Exposed fish had pericardial edema and deformities of skeletal tissues (loss of tail, lordosis, scoliosis, and kyphosis). Other histological alterations were limited to dysplasia, hyperplasia and metaplasia of skeletal tissues in the deformed fish. This study showed that a short exposure of embryos during somite development has significant effects on the musculoskeletal development. 相似文献
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Krishnan KP Fernandes SO Chandan GS Loka Bharathi PA 《Marine pollution bulletin》2007,54(9):1427-1433
The Mandovi and Chapora are two tropical estuaries lying in close geographic proximity on the west coast of India. Seasonal changes in down core variation of Fe, Mn and Total Organic Carbon (TOC) in the mangrove sediments adjoining these estuaries were studied to assess their influence on some of the representative benthic bacteria belonging to heterotrophic and autotrophic groups. Heterotrophic bacteria (HB) cultured on different nutrient concentrations (0.01%, 0.1% and 25%) together with nitrifiers (NtB; representating autotroph) were chosen to assess the influence of the above-mentioned abiotic parameters on the former. The experimental site located along the Mandovi is under the influence of extensive ferromanganese ore mining, while the control site at Chapora is relatively free from such influences. Geoaccumulation index computed for Mandovi showed that sediments (0-10cm) were 'uncontaminated to moderately contaminated' by Fe during the pre monsoon and monsoon seasons, while in the post monsoon season the 4-10cm fraction was almost completely restored from contamination. Similar computations for Mn showed that in pre monsoon, sediments fell in the 'moderately contaminated' and 'moderately to strongly contaminated' categories, while in the monsoon and post monsoon seasons all the sections were 'Uncontaminated'. The difference observed in correlation between Fe and Mn with the various fractions of heterotrophs and nitrifiers indicated that though these two elements shared a similar chemistry in the environment, microbes involved in biogeochemical processes might prefer them differentially. The relationship between TOC and HB enumerated on 0.01% dilute nutrient agar remained at r=0.50, p<0.05 throughout the year. Hence, it could be apparently linked to their preferred concentration of organic carbon requirement. A relationship of r=0.61, p<0.01 between manganese concentration and heterotrophs recovered on different strengths of nutrient agar is suggestive of their response to the metal enrichment. They could thus contribute towards maintaining the level of Mn at par with reference levels at Chapora. A positive correlation between Mn with NtB (n=10, p<0.05, r=0.58) at the experimental site during the non-monsoon months is suggestive of the latter's contribution to regulation of the metal concentration in the sediment probably through anaerobic nitrification at the expense of manganese. The study therefore supports our hypothesis that both autochthonous autotrophs and heterotrophs work in tandem to mitigate concentration of Mn and related metals in mangrove sediments. 相似文献
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The Sinuiju Formation in Paekto-dong, Sinuiju City in the Democratic People's Republic of Korea has yielded Mesozoic nonmarine bivalve fossils, which is the first occurrence of such in the DPRK. Based on these fossil specimens, a new Cretaceous bivalve assemblage, the Arguniella yanshanensis-Sphaerium anderssoni Assemblage is erected. This assemblage includes Arguniella yanshanensis, A. lingyuanensis and Sphaerium anderssoni and can be compared with the Jehol Biota. The age of the Sinuiju Formation is also clarified and on the basis of the bivalves and the presence of a Eosestheria–Ephemeropsis–Lycoptera(E–E–L) assemblage, the formation is not Upper Jurassic, but Lower Cretaceous in age. 相似文献
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Ｈｗａｎｇｇａｎｇｒｉ成矿区位于汉城东南大约１３０ｋｍ的南韩古生代Ｏｇｃｈｅｏｎ带之内。此矿区中的Ｊｕｎｇｂｏ矿、Ｓｕｒｉ矿和Ｄｅｏｇｍａｎ矿产于晚白垩世Ｓｕｓａｎ花岗岩周围并位于含Ｗ－Ｍｏ的石英矿脉中。这些矿脉育填了花岗岩中的裂隙，其母岩包括早古生代的富含灰岩的沉积岩。 相似文献
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区域可持续发展指标的相关性分析及降维模型研究——以中国省级区域为例 总被引：12，自引：0，他引：12
增大指标的覆盖面与减少指标的信息重复是可持续发展指标选取中面临的一对矛盾。在通常情况下指标数量越多，指标的覆盖面就越大，但指标的信息重复就越多。分析了近年来有关文献通常采用的指标，并结合中国省级区域可持续发展指标的可获取性，选取46个指标对其相关性进行分析。分析结果表明这些指标之间绝大多数呈现不同程度的相关关系，即指标间含有大量的重复信息。应用统计分析技术建立基于主成分分析的指标降维模型，得到 8个彼此独立的综合指标。根据综合指标得分，对中国31个省级区域（不包括港澳台）的可持续发展状况进行了排序。 相似文献
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