Historical trends of PCBs and PBDEs as reconstructed in a lake sediment from southern Tibetan Plateau

High-altitude lake sediment can be used as a natural archive to reconstruct the history of pollutants. In this work, the temporal distribution of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) were determined using a high-resolution gas chromatography coupled with high-resolution mass spectrometer (HRGC/HRMS) in an alpine lake sediment core collected from the southern Tibetan Plateau (TP) to examine whether the expected decreasing trends due to the implementation of the international Conventions could be observed. The concentrations of PCBs and PBDEs in the sediment core were in the range of 11.8–142 pg/g dw and ND-457 pg/g dw, and their fluxes were in the range of 2.51–31.7 ng/(m²·yr) and ND-43.2 ng/(m²·yr), respectively. The prevalence of low-chlorinated (tri-CB) PCBs and low-brominated (tri- to tetra-) PBDEs in most sections of the sediment profiles was observed, suggesting that the light molecular weight PCBs and PBDEs have most likely reached lake sediments by long-range atmospheric transport from distant sources. Despite the restrictions on their applications, the sediment records for the concentrations and fluxes showed no corresponding decreasing trend with restrictions for PCBs, which suggested that these POPs (e.g., PCBs) were still emitted to the environment owing to the influence of primary or secondary emissions. To our knowledge, this is the first report on input history of atmospheric PCBs and PBDEs recorded in TP Lake sediment.     

云南稻核心种质苗期耐冷性及其地理生态差异

采用Nagamine等(1991)法研究了598份云南稻核心种质在稻作区划间、地州间苗期耐冷性强弱、变异程度及其地理生态差异。结果表明,稻作区划间苗期耐冷强弱差异较大,平均耐冷级别为:I(4.70)>II(4.78)>V(4.79)>III(5.34)>IV(5.36),40份强耐冷种质频率为II(45%)>I(25%)>III(22.5%)>V(5.0%)>IV(2.5%),其变异系数为II(32.22%)>I(31.28%)>V(29.65%)>III(19.66%)>IV(19.59%);揭示了苗期耐冷性与低温胁迫下水稻冬春育秧、冷泉水密切相关,其耐冷基因源是云南南部地区冬季育秧和滇中一带苗期倒春寒长期协同进化的结果;苗期耐冷种质广泛存在于热带、亚热带和温带地区,品种间苗期耐冷差异也明显。云南稻核心种质16个地州平均苗期耐冷强弱差异较大。根据气候、生态、云南稻种多样性及其苗期耐冷性等将云南稻作区划分为重冷害多样性贫乏区、冷害多样性中区和轻冷害区三部分。其中,曲靖、大理、楚雄、昆明和丽江5个地州平均耐冷级别3.65~4.32,0—2级苗期强耐冷种质占27.5%(2.5%~10%)和高海拔冷泉水苗期灌溉,属于重冷害多样性贫乏区;文山、红河、思茅、保山、德宏和临沧6个地州平均耐冷级别4.45~5.40,0—2级苗期耐冷种质占70%(5%~30%)和冬春育秧,属于冷害多样性中区;怒江、玉溪、昭通、迪庆和西双版纳5个地州平均耐冷级别5.05~5.87,0—2级苗期耐冷种质占2.5%(0~2.5%),属于轻冷害多样性扩散区。水稻冬春育秧和高海拔冷泉水灌溉在云南稻核心种质苗期耐冷基因源演化中起了重要作用。     

Use of Water Clarity to Monitor the Effects of Climate Change and other Stressors on Oligotrophic Lakes

We present evidence from studies oflakes in Killarney Park, Ontario, Canada that waterclarity is a key variable for monitoring theeffects of climate change, high UV exposure andacidification. In small oligotrophic lakes, thesestressors affect water clarity primarily byaltering the concentration of DOC in lake water. Clear lakes (<2 mg L^-1 DOC) proved to be highlysensitive indicators of stressors, exhibiting largethermal and optical responses to small changes inDOC. Extremely clear (<0.5 mg L^-1 DOC) acidic lakesshowed the effects of climate change and solarbleaching in recent decades. These lakes becamemuch clearer even though they were slowlyrecovering from acidification.     

中国边缘海柱样沉积物中239+240Pu的分布与时标价值

根据中国边缘海已研究的77根^239+240Pu柱样沉积物,分析了柱样沉积物中^239+240Pu的来源、分布和时标特征.结果表明理论上给出的利用²¹⁰Pb、¹³⁷Cs和^239+240Pu 3种核素进行定年可能出现的26种情况,与实际情况完全吻合.中国边缘海海陆交汇,柱样沉积物中不同来源的^239+240Pu沉积叠加使得近岸海域（尤其是河口区）柱样沉积物中^239+240Pu的峰型轮廓明显.从近岸到远海,受到沉积物来源方式、海水深度、黑潮混合、扩散效应和边界清除效应等综合因素的影响,柱样沉积物中^239+240Pu的分布可能出现双峰（多峰）、单峰和无峰的情况.其中,柱样中^239+240Pu呈现单峰分布时,与全球大气沉降的高峰年1963年相对应,时标价值可靠.不同海洋环境条件下²¹⁰Pb、¹³⁷Cs和^239+240Pu定年的可靠性,应根据具体海洋沉积环境进行分析;海水中¹³⁷Cs和^239+240Pu核素沉积性质的差异,可能导致沉积峰不一致而影响定年的判断.     

完善与发展重大突发事件情景构建技术方法的核心问题

重大突发事件情景构建是近年在我国兴起的支撑应急准备能力建设的一种方法和思路,广泛应用于公共安全领域的预案体系管理、应急演练设计、应急体系规划等应急准备行动。但是,随着相关研究和应用的逐年深入,如何将其进一步总结、凝练,进而发展成为突破层级和业务领域的标准化风险管理方法是当前应急管理领域急需解决的问题之一。首先,从重大突发事件情景构建的重要性与必要性入手,总结回顾目前国内外情景构建相关的研究与应用现状;其次,在情景构建理论体系和应用实践总结的基础上,围绕“综合风险评估和专家观点的情景主题筛选”“基于专业知识和真实案例支撑的‘故事化’表达”“基于通用应急任务清单支撑的任务梳理”和“基于任务驱动的风险沟通机制”4个核心理念进行深入分析和讨论;最后,结合目前我国应急管理机构改革的情况,从情景构建标准体系的建立和基于标准的情景构建实践工作出发,提出针对性建议。研究结果可为重大突发事件情景构建标准体系的建立与推广提供理论基础和参考借鉴。     

高层建筑安全核区域防排烟技术探讨

本文在某高层安全核区域设计了一系列现场实验,通过送风系统和机械排烟的不同开启、关闭组合方式,定性判断送风与排烟的相互作用。结果显示：在送风量略大于排烟量的前提下,烟气层能够稳定在一定的高度,对人员的安全疏散是最有利的。因此,本文提出在满足楼梯间及其前室足够正压值的前提下,改造现有的送风系统,利用多余的正压值进行补气,以优化高层建筑内的防排烟效果。     

核心期刊确认及其应有中的问题

核心期刊的确认工作有着重要的理论和现实意义,本文从核心期刊的作用、国内外核心期刊鉴定工作现状、筛选核心期刊的理论方法等三方面进行了综述,分析了其确认和应用中存在的问题,并提出相应的建议。     

苏北盆地里下河地区30~15 cal ka BP期间地球化学元素变化特征及古气候意义

应用因子分析法对苏北盆地里下河地区SG剖面中的地化元素和氧化物进行分析,提取出相关古气候信息,重建了苏北盆地里下河地区30~15cal ka BP期间的古气候环境演化序列:30.3~26.0cal ka BP为相对暖湿期;26.0~17.8cal ka BP较为显著的冷干期;17.8~15.0cal ka BP以升温为主,冷暖波动剧烈,整体相对暖湿期;另外,在这些大的气候演变背景条件下,也存在着多次明显的气候波动事件。这一研究结果不仅与国内大量的研究资料相一致,而且与深海氧同位素和北半球太阳辐射等曲线也有着很好的对应,表明苏北地区的气候变化具有全球性特征。     

厦门西港潮间带柱状沉积物重金属赋存形态与污染评价

采用改进的BCR四步提取法研究厦门西港潮间带柱状沉积物中12种重金属元素(Ba、Co、Cr、Cu、Fe、Mn、Zn、Ni、Pb、Sr、V和Ti)不同形态的分布特征,并利用次生相和原生相比值法进行重金属污染评价。结果表明:在1975~2013年所对应的沉积柱中,Fe、Zn、Ba、Ti、Co、Cr、Ni、V和Cu主要以残渣态为主,Sr和Mn主要以弱酸溶态赋存,Pb以可还原态和残渣态为主。次生相和原生相比值法评价结果表明,Pb在1981~1983年、1991~2003年处于轻度到中度污染水平,作为生物成因元素的Sr和Mn不适于用本法评价,其他金属均未受到污染。     

Characteristics of heavy metals and Pb isotopic signatures in sediment cores collected from typical urban shallow lakes in Nanjing, China

To investigate the contamination levels and sources for heavy metals that have occurred during the development of cities, sediment cores collected from typical urban shallow lakes (Xuanwu Lake and Mochou Lake) in Nanjing, China were analyzed for Cu, Pb, Zn, Cd, Cr, Ni, and for Pb stable isotopic ratios. No significant differences were found in the concentrations of Cu, Ni and Cd among sediment layers from Xuanwu or in the levels of Cr and Ni among sediment layers from Mochou. However, there were significant differences among the layers in the concentrations of Cr, Zn and Pb in Xuanwu and Cu, Zn, Cd and Pb in Mochou. Based on geoaccumulation indexes and enrichment factors, Cd was the primary pollutant at all depths in the sediment cores. The ratios of (206)Pb/(207)Pb and (208)Pb/(206)Pb differ significantly among sediment layers in Xuanwu. No significant differences were found on the ratios of (208)Pb/(206)Pb in Mochou, but the ratios of (206)Pb/(207)Pb differ significantly among some of the sediment layers in Mochou. The range of (208)Pb/(206)Pb and (206)Pb/(207)Pb ratios was found to be 2.098-2.106 and 1.170-1.176, respectively, for sediment cores from Mochou Lake and 2.091-2.104 and 1.168-1.183, respectively, for cores from Xuanwu Lake. The differences in heavy metal concentrations and the Pb isotopic ratios with depth for the cores from Xuanwu and Mochou confirmed that the contamination sources changed during the formation of the different sediment layers. Furthermore, the ratios of (206)Pb/(207)Pb demonstrated that gasoline and vehicular Pb were not the primary sources of Pb contamination at different depths in the sediment cores in Xuanwu Lake and Mochou Lake.