Effects of N-acetyl-L-cysteine on fish hepatoma cells treated with mercury chloride and ionizing radiation

Organisms are exposed to natural radiations from cosmic or terrestrial origins. Furthermore the combined action of radiation with various chemicals is an inevitable feature of modern life. Radiation is known to cause cell death, mainly due to its ability to produce reactive oxygen species in cells. N-acetyl-l-cysteine (NAC) is a well-known sulfhydryl-containing antioxidant whose role in radioprotection has been reported. Synergistic effects of radiation and mercury chloride on human cells was previously reported by the authors. Based on the previous report, this study was designed to assess the synergistic effects of radiation and mercury chloride on fish hepatoma cells, as well as to investigate the protective effects of NAC on the cells. The cytotoxicity of radiation was enhanced in the presence of mercury chloride. NAC in lower concentrations prevented cells from death after irradiation with lower doses (<300 Gy) while it did not prevent cells from radiation-induced death after irradiation with higher doses (300, 500 Gy). The intracellular glutathione (GSH) levels significantly decreased after irradiation while the combined treatment of NAC and radiation alleviated the decrease in the GSH levels. The investigations give a clue for the action mechanism of synergistic or protective effects of NAC on the cells. Due to their high resistance to ionizing radiation, the PLHC-1 cells can be effectively used as a screening tool for assessing the combined effects of radiation with toxic chemicals.     

巨型减振结构体系风振效应的参数影响研究

巨型结构风激振动特性非常复杂,其动力性能受多种参数的影响。为合理考虑这些因素的影响,以某48层巨型钢结构为研究对象,针对无控、设置粘滞阻尼器和粘弹性阻尼器三种分析工况,系统研究了其在平均风和脉动风荷载共同作用下的动力响应。通过结构顺风向侧移响应、构件内力响应及顶层加速度响应等一系列数据,揭示了风速攻角、基本风压、附加阻尼比及二阶效应等对此类结构体系风振控制动力性能的影响规律与变化趋势,并依据分析结果对其抗风分析与设计提出了相应的建议,因而具有实用参考价值。     

工业经济结构、经济增长对环境污染的非线性影响

本文从生产要素投入端将环境污染引至索洛增长模型,理论考察工业经济结构、经济增长对环境污染的非线性影响机制,基于1999—2014年我国30个省份的面板数据,以SO_2排放量作为环境污染水平的代理变量,采用面板平滑迁移回归(PSTR)模型检验全国及分区域工业经济结构、经济增长对环境污染的非线性影响效应及区域差异性。研究结果表明:随着工业化进程的不断加快,工业产出及污染排放均呈现不断上升的趋势,但由于资本边际收益递减规律使得这种增长趋势逐渐减弱,最终导致经济增长和环境污染增长趋于稳态,当污染排放增长率降低为负时,经济增长对环境污染的影响作用由正向转变为负向。实证表明我国工业经济结构、经济增长与SO_2排放具有显著的产出水平门槛效应,随着经济产出水平由低区制平滑的过渡到高区制,经济增长对SO_2排放的影响由正向促进作用转变为负向减排效应,但工业经济结构对SO_2排放呈现逐渐增强正向促进作用,可见工业经济结构、经济增长对SO_2排放具有显著的非线性影响。此外,研究发现工业经济结构、经济增长对SO_2排放的非线性影响存在显著的区域差异性,东部地区经济增长与SO_2排放呈现显著的倒"U"型曲线关系,而在中西部地区表现出逐渐增强的促进作用,中部地区的工业经济结构对SO_2排放的促进作用最大,西部其次,东部最弱,研究还表明,减排技术水平以及环境治理投资增加对SO_2污染排放具有遏制作用,能源投资的增加加速了SO_2的排放。在未来经济发展中,应摒弃传统"高投入、高消耗"的工业化模式,政府应实施创新管理,完善环境保护立法,鼓励企业发展环境污染治理方面的技术,避免以环境容量过渡为代价,追求工业经济高质量、可持续发展模式。     

水培实验中不同粒径纳米TiO_2对芦苇种子发芽和植株生长和生理的影响

纳米二氧化钛(TiO_2-NPs)是目前应用最为广泛的纳米材料之一,进入到天然湿地和人工湿地中的TiO_2-NPs会在湿地生物、基质、水体之间进行迁移转化和归趋。目前针对TiO_2-NPs对湿地植物芦苇的毒性研究很少。本文采用水培实验方法,研究了不同粒径TiO_2对芦苇种子发芽和植株生长的影响,解析了TiO_2-NPs对芦苇的生态毒理效应。研究结果表明:几种粒径的TiO_2-NPs在较低浓度(≤200 mg·L~(-1))下对芦苇种子发芽均具有一定的促进作用,高浓度处理会抑制芦苇种子发芽;当TiO_2-NPs浓度为500 mg·L~(-1)时,处理后的芦苇种子的发芽指标较空白对照均出现显著降低,4 nm和20 nm的TiO_2-NPs对芦苇种子发芽的半数有效浓度(EC50)分别为1 075 mg·L~(-1)和1 680 mg·L~(-1)。TiO_2-NPs对芦苇植株的毒害作用表现为植株生长速度减缓甚至停滞、叶片失绿、植株萎焉或枯死、芦苇倒二叶面积增长率降低,并且TiO_2-NPs的粒径越小、浓度越高毒害作用越明显。随TiO_2-NPs浓度升高,处理后芦苇叶片的叶绿素含量和植株体内的Mg含量均降低,根系的超氧化物歧化酶(superoxide dismutase,SOD)活性、丙二醛(malondialdehyde,MDA)均升高,而且越小粒径的TiO_2-NPs对芦苇的处理效果越明显。3种粒径的TiO_2-NPs均能进入芦苇体内,粒径越小、浓度越高进入的量越多,但是TiO_2-NPs比较难以从根迁移转运至茎和叶。     

依据(代)生物体对化学品的反应预测对生态系统服务功能的影响

保护生态系统服务功能越来越多地被作为风险评估的目标,但是目前生态风险评估的终点和评估生态系统服务功能受到的潜在影响之间有很大的差距。作者提出了一个框架,将常用的生态毒理学终点与对种群和群落的影响以及生态系统的服务功能联系起来。这个框架建立在机制效应模型的长足进步上,这些模型旨在跨越多种生物组织,并解释各种生物相互作用和反馈。为了说明这一点,作者引入了2个研究案例,它们采用了已完善和已验证的机制效应模型：鱼种群的inSTREAM个体模型和AQUATOX生态系统模型。他们还展示了动态能量平衡理论可以为解释组织级毒性提供一种通用货币。他们认为,一个基于机制模型的框架,可以预测化学品暴露对生态系统服务的影响,再结合经济估值,可以为环境管理提供一种有用的方法。作者强调了使用这个框架的潜在好处以及未来工作中需要解决的挑战。
精选自Forbes, V. E., Salice, C. J., Birnir, B., Bruins, R. J.F., Calow, P., Ducrot, V., Galic, N., Garber, K., Harvey, B. C., Jager, H., Kanarek, A., Pastorok, R., Railsback, S. F., Rebarber, R. and Thorbek, P. (2017), A framework for predicting impacts on ecosystem services from (sub)organismal responses to chemicals. Environmental Toxicology and Chemistry, 36: 845–859. doi: 10.1002/etc.3720
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3720/full
     

农药内分泌干扰效应研究进展

农药作为农业生产过程中的一类重要生产资料,主要用作杀虫剂、杀菌剂和除草剂等。由于农药的大量使用,目前在各类农产品及各种环境介质中都能被检测到,对饮食健康和环境安全带来潜在危害。研究发现,许多农药为内分泌干扰物,其能够干扰人类和其他生物体的内分泌系统正常功能。本文在总结国内外相关研究的基础上,对农药内分泌干扰效应的作用机理及筛选模型进行总结,对有机氯、有机磷和拟除虫菊酯等各类农药的内分泌干扰效应研究进展进行综述,并提出深入探究农药致毒作用机制和低剂量下多种农药联合毒性是本领域的重要研究方向。     

全氟辛酸(PFOA)对菲律宾蛤仔体内酶活性的影响

采用半静态毒性实验方法,将菲律宾蛤仔(Ruditapes philippinarum)分别暴露于0.2、2、20μg·L-1的全氟辛酸(perfluorooctanoic acid,PFOA)中,在处理后第1、3、6、10、15、21天分别取样,测定整体组织中超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、谷胱甘肽-S-转移酶(GST)、7-乙氧基异吩噁唑酮脱乙基酶(EROD)活性和过氧化脂质(LPO)含量。酶活性分析结果显示:PFOA对菲律宾蛤仔组织SOD、CAT和POD活性均呈现先促进后抑制的作用;低浓度组SOD活性在暴露第1天达到最高,显著高于对照组(P<0.01);中高浓度组SOD活性在暴露第6天达到最低;暴露1~15 d,低浓度组CAT活性均显著高于对照组(P<0.05);高浓度组CAT活性在暴露第6天得到显著诱导,其余时间基本处于抑制状态;中浓度组POD活性在暴露第3天即达到最高,高浓度组POD活性基本一直处于抑制状态;随着PFOA暴露时间的延长,菲律宾蛤仔组织LPO含量呈现了先降低后升高的趋势;各浓度组中EROD的活力都显著被诱导(P<0.01),与处理浓度呈正相关;中高浓度组的GST活性在胁迫期间变化比较显著,呈现诱导-抑制的变化规律。研究表明,PFOA暴露能够引起菲律宾蛤仔组织抗氧化酶和生物转化酶的变化,可以与其他敏感性指标一起作为指示早期海洋PFOA污染的生物标志物。     

氯代阻燃剂得克隆对纤细裸藻的生态毒性效应

得克隆(Dechlorane Plus,DP)作为全球广泛使用的氯代阻燃剂,具有POPs特性和环境毒性,但其生物毒性数据非常有限。本文选择水生初级生产者纤细裸藻(Euglena gracilis)作为研究对象,通过检测藻细胞生长状况、光合色素水平、抗氧化酶活性、谷胱甘肽(GSH)和丙二醛(MDA)含量变化,研究了不同浓度DP对其生态毒性效应的影响。结果显示,低浓度DP对纤细裸藻生长具有一定促进作用,但差异不显著;DP浓度较低时(0.1和0.5 mg·L-1DP)类胡萝卜素含量受到轻微抑制;较高浓度DP暴露导致超氧化物歧化酶(SOD)、过氧化物酶(POD)和谷胱甘肽(GSH)水平显著增加,同时高浓度DP(8 mg·L-1)下MDA含量显著上升,提示膜结构受到损伤;表明较高实验浓度范围内,DP对纤细裸藻的生长及抗氧化系统均产生一定影响,结果将为DP的环境生态风险评价提供科学依据。     

Back-pedaling or continuing quietly? Assessing the impact of ICLEI membership termination on cities’ sustainability actions

Over the past decade, cities have emerged as leaders in sustainability and climate protection in the United States. ICLEI, a voluntary network of local governments, played an important role driving this trend. After years of steady growth, ICLEI became a target of political opposition and its membership dropped significantly from 2010 to 2012. This begs the question of whether cities’ termination of their ICLEI affiliation diminishes their implementation of sustainability actions. Two surveys administered in 2010 and 2014 provide data on cities’ implementation of an array of sustainability actions. Using a difference-in-differences (DiD) method, the impact of ICLEI termination on local governments’ administrative and policy commitments to sustainability is assessed. The results suggest that ending ICLEI membership does not significantly impact local sustainability actions, and also indicate that the durability of policy actions may be only loosely linked to the policies that justify them.     

Media Use and Public Perceptions of Global Warming in India

Media plays a vital role in informing the public about environmental threats. Although climate change is a global problem, developing countries such as India are often more vulnerable to the impacts due to poverty, illiteracy, and low public awareness. Using data from a nationally representative survey in India, this paper explores the relationships between media use, issue attention, and trust in informational sources on one hand and science-based climate change beliefs, risk perceptions, and policy support on the other. Results suggest that the Indian media, through consistent and accurate coverage of global warming using trusted sources, can play a positive role in increasing public engagement among a largely unaware population. Implications for climate change communication in India are discussed.