Genotoxic effects of metals on human salivary gland tissue and lymphocytes as detected by the Comet assay

The etiology of salivary gland malignancies still remains unclear. Metal compounds are of special interest since they show ubiquitous presence in the environment, are present in many working places, and are accepted (co-)carcinogens in some other malignancies. Metals enter the body as xenobiotics by inhalation or ingestion. This study investigated the genotoxic potential of sodium dichromate (Na₂Cr₂O₇), nickel sulfate (NiSO₄), cadmium sulfate (CdSO₄) and zinc chloride (ZnCl₂) on human salivary gland cells and lymphocytes. Macroscopically healthy tissue of salivary glands was harvested from 46 patients during surgery and isolated to single cells by enzymatic digestion. The cells were incubated with Na₂Cr₂O₇, NiSO₄, CdSO₄ or ZnCl₂. Na₂Cr₂O₇ was also incubated in combination with the other metal compounds listed. Carcinogenic and co-carcinogenic effects of cadmium were tested by incubation with Na₂Cr₂O₇ and consecutive repair intervals. DNA damage and repair were evaluated by the Comet assay, determining DNA-strand breaks. The extent of damage was quantified using a digital analysis system. Na₂Cr₂O₇ produced significantly enhanced DNA-strand breaks in human salivary gland tissue and lymphocytes. All other metal compounds exerted no damaging effect on both cell types. Co-incubation of Na₂Cr₂O₇ with the other metals revealed a significant additive effect only for CdSO₄. Specific analysis of the influence of cadmium showed a reduction of DNA-repair after Na₂Cr₂O₇-induced strand breaks in salivary gland cells. This study provides evidence that exposure to distinct metals may significantly contribute to malignant salivary gland tumors. In consequence, further studies as epidemiological and toxicological data are warranted to determine the role of distinct metals as potential (co-) carcinogens.     

Mercury pollution in the Sonbhadra district of Uttar Pradesh,India, and its health impacts

The Sonbhadra district in the Singrauli area of Uttar Pradesh, India, has many coal mines and thermal power plants and is a critically polluted area. Many residents of this area reported adverse health conditions which may be linked to metal pollution, especially of mercury investigated here.

In May 2012, samples of water (23), soil (7), blood, hair, and nails from persons showing adverse health conditions selected at random were collected and analyzed for total mercury by atomic absorption spectrometry.

Twenty percent drinking water samples contained mercury from 3 to 26 μg L^?1 (3–26 times the permissible limit). Soil samples had 0.5–10.1 mg kg^?1 Hg.

The average concentrations of mercury in human blood, hair, and nails were found to be 34 μg L^?1, 7.4 mg kg^?1, and 0.8 mg kg^?1, respectively. Mercury concentrations in the blood of these persons were 45 and 28 μg L^?1 on average in the case of men and women. This is much higher than the safe level of 5.8 μg L^?1 set by the United States Environmental Protection Agency (USEPA).

It was concluded that all residents of Sonbhadra sampled could be suffering from mercury toxicity as the area is polluted by Hg released from the coal-fired thermal power plants.     

The cytotoxicity of nici2 for mammalian cells in culture†

The effects of NiCl₂ were studied in two human cell lines, HeLa and diploid embryonic fibroblasts as well as in V79 Chinese hamster cells and in L‐A mouse fibroblasts. NiCl₂ produces a dose‐dependent depression of proliferation, mitotic rate, and viability, accompanied by an increasing release of lactic dehydrogenase and stimulation of lactic acid production. The plating efficiency is reduced, as are DNA and protein synthesis and, to a lesser degree, RNA synthesis.

The cytotoxicity of NiCl₂ is comparable in degree to those of PbCl₂ and MnCl₂, but is weaker than those of HgCl₂ and CdCl₂. However, the different sensitivities of different cell lines must also be considered.

NiCl₂ effects are more severe in serum‐free medium than in medium containing serum or serum albumin indicating that serum constituents, notably albumin, bind the metal effectively and inhibit cellular uptake; this confirms earlier reports on the serum binding and slow uptake of NiCl₂.

Synchronized cells are most sensitive in the Gl and early S phases of the cell cycle. In the Painter test the depression of DNA synthesis persists following cessation of exposure to NiCI₂. These findings contribute an explanation for the known genotoxic effects of nickel.     

辛置煤矿水力压裂卸压增透影响半径数值模拟研究

随着开采深度的增加,辛置煤矿瓦斯涌出量显著增大。为了提高瓦斯抽采效率,拟采用水力压裂卸压增透技术。理论分析了水力压裂对煤层的卸压增透作用,基于此利用RFPA模拟软件对辛置煤矿2-559回采工作面水力压裂卸压增透进行了数值模拟。研究表明,水力压裂主要在以下3个方面对煤体起到增透作用:使煤体卸压、提高煤层透气性;湿润煤体,增加塑性;改善瓦斯抽放环境。辛置煤矿2-559回采工作面水力压裂所需压力约为15MPa,压裂半径为5-6m,以此可以初步确定现场施工过程中水力压裂钻孔间距以不大于10m为宜。     

温度对烃类物质爆炸极限的影响及其预测模型研究

为研究温度对烃类气体爆炸极限的影响,利用爆炸极限测试仪对C1-C4烃类气体在20℃、60℃、100℃、140℃等初始温度条件下的爆炸极限进行了测试。结果表明:C1-C4烃类气体的爆炸下限在20-140℃范围内与温度呈线性关系,同一系列烃类物质,随着碳原子数的增加,同一温度下所对应的爆炸下限数值依次降低;对于相同碳原子数的烃类物质,相同温度下烷烃的爆炸下限数值高于烯烃的爆炸下限数值。此外,建立了高温条件下烃类物质爆炸极限的预测模型,为烃类物质爆炸极限的预测提供了一种方法。     

Natural and Anthropogenic Effects On Phytoplankton Primary Productivity in Mangroves

Abstract

Spatial and temporal variations and the factors influencing primary production have been studied in three different mangrove waters (Pichavaram, Ennore Creek and Adyar Estuary) of South India characterised by different anthropogenic impacts. the gross primary productivity in the unpolluted Pichavaram mangrove was 113 g Cm^?2yr^?1 exhibiting natural variability with the environmental forcing factors. Human activities have elevated primary productivity in the Ennore Creek mangrove (157g Cm^?2yr^?1) primarily through the direct discharge of fertilizer effluents. By contrast, a combination of domestic and industrial effluent discharges into the Adyar Estuary mangrove has considerably reduced phytoplankton primary productivity 83g Cm^?2yr^?1 the Redfield N: P ratio varies from 0.96 N: 1P at Ennore Creek, 1.75N: 1P at Adyar Estuary to 15.2 N: 1P at Pichavaram mangroves. This suggests that the Pichavaram mangroves represent a well equilibrated ecosystem with N: P ratio close to steady-state values in contrast to the anthropogenically altered mangrove ecosystems studied. Results show a significant temporal variability in nutrient concentration in the three mangrove areas. Distinct differences in nutrient concentrations between the dry and the wet seasons have been observed.     

Demonstrating a correlation between infrastructure and national development

This paper demonstrates a correlation between the extensiveness of infrastructure and national development. This was achieved by considering kilometres of paved roads, kilometres of rail, kilometres of paved runways, quality of shipping ports and quality of urban infrastructure. Data were collected from a variety of sources including the World Bank and the United Nations databases. Measures of the quantity or extensiveness of the infrastructures were normalized based on the populations of the various countries, transforming them into per capita measures, which were then logarithmically transformed to produce indices of the extensiveness of the infrastructures. These indices were then plotted against the national development indicator, the human development index (HDI). Of the infrastructures considered, paved roads per capita index showed the strongest correlation with HDI, while quality of port infrastructure index showed the weakest correlation. When the indices for the different infrastructures were combined into a single index the correlation with HDI appeared to be strongest, highlighting the synergistic effect of different infrastructures when working in tandem. Based on this, the findings of this study support the position of holistically managing a country's infrastructure assets.     

全氟及多氟类化合物在人体分布及其毒性研究进展

全氟和多氟烷酸类化合物(perfluoroalkyl and polyfluoroalkyl substances, PFASs)是一类新型持久性有机污染物,目前其在民用和工业产品中得到广泛应用。在环境样品、野生动物以及人类体内都检测到了这类物质。PFASs对哺乳动物和水生生物具有广泛的毒性,其对生态环境和人体健康的影响受到公众关注。目前,PFASs对人类健康的研究还多停留在流行病学研究和体外细胞毒性研究方面,由于人类有复杂的免疫和代谢系统,因此PPASs对人类健康影响的具体机制和安全剂量仍然需要进一步研究。本文针对PFASs在人体的分布、流行病学研究、毒理学效应和作用机制等热点问题进行了总结,并对目前PFASs研究存在的问题及今后的研究方向进行讨论和展望。     

森林净生态系统生产力及其生物影响因子研究进展

在全球大气二氧化碳浓度上升的背景下,陆地生态系统碳循环及碳汇功能研究得到了广泛的关注,日益成为今后的政治和外交的重大议题之一.净生态系统生产力(net ecosystem production, NEP)是生态系统光合固定的碳与生态系统呼吸损失的碳之间的差值;或者为生态系统净的碳积累速率.NEP 的研究整合生态系统地上和地下部分,把生态系统碳循环的影响因子有机地联系了起来.当NEP为正值时,说明生态系统为碳汇,NEP为负值则表明生态系统为碳源.随着植物和土壤相互联系及其对生态系统过程研究的深入,NEP已经成为生态系统碳循环研究的核心概念之一.以森林NEP为出发点,综述了国内外的最近的 NEP 研究进展,分析了 NEP 研究的科学意义;探讨了植物群落组成/生物多样性、土壤微生物群落、大型/土壤动物和人为的管理或干扰等生物因子对NEP的影响.根据综述研究提出未来研究应在:(1)土壤生物过程、土壤食物网及其与地上部分植物/动物相互作用对NEP的影响;(2)自然林生物多样性的竞争/共存机制与生态系统碳吸存稳定性;(3)人工林固碳潜力和不同植物功能群(灌草层)对生态系统碳动态影响等方面加强,以期为全面认识生物因子对森林生态系统系统固碳现状、机制和潜力提供理论基础.     

大气环境影响评价现状空气质量监测布点技术方法

基于HJ2.2—2008《环境影响评价技术导则-大气环境》的规定,结合某石化焦化扩建案例实践,对大气环境影响评价现状空气质量监测方案的制定、监测布点原则与技术要点进行了深入系统地研究,进一步探讨了在环评中执行的具体问题及解决方案。