纳米银和银离子对2种微藻的急性毒性效应

为了探讨AgNPs对典型微藻的急性毒性效应及其机制,采用柠檬酸钠还原法制备AgNPs,以摇瓶实验法评估了不同浓度的AgNPs和Ag+对铜绿微囊藻和普通小球藻叶绿素a含量、形态结构和叶绿素荧光参数的影响。实验结果表明:AgNPs对普通小球藻和铜绿微囊藻的96 h-EC50分别为1.113 mg·L-1和0.697 mg·L-1,而Ag+对2种藻的96 h-EC50分别为0.106 mg·L-1和0.032 mg·L-1。扫描电镜结果表明:AgNPs处理使普通小球藻细胞表面出现褶皱,细胞变形甚至向内塌陷。对铜绿微囊藻部分细胞出现变形变得不规则,且出现某些胞外物质使细胞粘附在一起。透射电镜观察发现,高浓度Ag+处理使2种藻的细胞均发生质壁分离,部分细胞转变为孢子。而AgNPs处理使普通小球藻细胞蛋白核增大,蛋白核与类囊体区无明显连接通道。铜绿微囊藻拟核区膨大,类囊体和色素体被推向四周,部分类囊体断裂,同时,发现该藻可以分泌胞外物质在细胞周围吸附AgNPs颗粒。对于普通小球藻,0.6 mg·L-1AgNPs处理后细胞光系统Ⅱ的最大光化学量子产率ΦP0相对于CK没有显著差异,但0.09 mg·L-1Ag+处理使ΦP0显著增加。在高浓度AgNPs或Ag+处理时,ΦP0均显著降低。AgNPs未对普通小球藻光系统II性能参数PI_Abs造成影响,但不同浓度Ag+处理均使得该参数显著升高。对于铜绿微囊藻,2种毒物均使其ΦP0显著降低。而PI_Abs仅在2种毒物的最高浓度处理时显著降低。综上,AgNPs对2种藻的急性毒性远小于Ag+,而两者对铜绿微囊藻的毒性均大于普通小球藻。AgNPs胁迫使2种藻叶绿素a含量显著降低,并诱导2种藻在形态结构和光合生理方面发生了显著变化,造成不同程度的损伤,但与Ag+的毒性效应存在一定的差异。提高光吸收能通量补偿耗散能量和分泌胞外物质结合Ag+是微藻2种重要的解毒机制。     

Subcellular Mn compartation, anatomic and biochemical changes of two grape varieties in response to excess manganese

To explore the underlying mechanism for the high tolerance to excess manganese stress in the grape species (Vitis vinifera Linn), we observed the subcellular compartment of Mn element, anatomic and biochemical responses of two grape cultivars (Combier and Shuijin) under excess Mn stress in semi-controlled environmental condition. Grape species exhibited typical detoxifying or tolerant mechanism as following: first, majority of Mn element accumulated in leaf was excluded into cell wall or comparted into cell vacuole to avoid cellular Mn-toxicity; Mn and other elements were also secreted into leaf surface or deposited in vascular wall; second, only small amount of Mn was located in cellular organ, and excess Mn in chloroplast was detoxified by depositing in starch granule, which serve as a novel detoxifying strategy; additionally, the cellular Mn was further chelated by phytochelatins; third, to quench the toxic oxygen radicals, the total phenolic compounds and polyamine (putrescine and spermidine) were enhanced. Although the obvious symptom of Mn-toxicity was not detected, we observed the dessication symptom under high level of Mn treatment in the two cultivars, such as sunk stomata, thickened palisade tissue, enhanced palisade/spongy tissue ratio and abscisic acid concentration. The growth inhibition and dessication symptom in the two grape cultivars could be largely associated with osmotic stress resulted from high concentration of leaf Mn.     

低碳旅游概念辨识及其实现途径

随着节能减排、应对气候变化等概念的实践和推广,低碳旅游也越来越多的被提及和实践。低碳旅游由于其新,无国际经验可循,在概念、内涵以及实现途径等方面认识还不够深入,甚至形成了一些认识的误区,实践中可能因为认识的偏误,阻碍旅游业的发展,而忽略了"低碳发展"所特有的协同发展与控制温室气体排放的积极意义。本文认为,低碳发展是异于传统旅游业发展模式的一种转型发展方式,具有明确的保护气候环境的目的。同时,旅游业是主张消费和体验的行业,低碳旅游不应该以刻意减少或约束消费和体验为手段来实现,低碳旅游的实现途径是多样的,不仅仅有节能减排,还可以根据不同地区的资源条件,选择以成本最低的方式实现低碳发展。我国正处于经济和旅游业的快速发展期,实践低碳旅游发展必然会面临更多挑战,但尽早实现低碳旅游发展转型,不仅对发展低碳经济、保障气候安全做出贡献,也能为改善生态环境,保障能源安全,实现可持续发展做出贡献。     

Carbon productivity convergence club and its initial conditions: China’s construction industry

A three-stage method is proposed to study the convergence clubs for the dynamic total factor carbon productivity (DCP) and the initial conditions. The first stage is to measure the DCP that reflects the initial difference. The second stage is to identify the convergence club of DCP. The last stage is to examine the initial factors that may affect the formation of the convergence club. Construction industry data from 30 provinces in mainland China from 2005 to 2016 were adopted to conduct an empirical study. The empirical results showed that (1) the arithmetic mean value of China’s provincial DCP showed an upward trend and the standard deviation showed an expanding trend. (2) There are five convergence clubs, but 13 provinces failed to converge to any club. (3) The higher the degree of construction industry marketization in 2005, the greater the probability that the provinces belong to a club with higher DCP. To improve the DCP, the effective diffusion of low-carbon construction technologies and the market-oriented reform of state-owned construction companies should be promoted. The three-stage method can also be applied to study different industries in different countries or regions.     

离子色谱法测定海水中的铵离子

采用新型柱填料的阳离子色谱柱,改善了铵离子与钾离子,钠离子的分离度,消除了大量钾离子和钠离子对铵离子测定的干扰。在硫酸和甲烷磺酸两种分离体系中,铵离子的检出限分别达到０．１ｍｇ．ｌ＾－１和０．０５ｍｇ．ｌ＾－１,线性范围分别为０．２－５０ｍｇ．ｌ＾－１和０．１－５０ｍｇ．ｌ＾－１。在两种淋洗条件下测定复杂基体海水中的铵离子,所得结果一致,该方法简便易行,灵敏度高。     

Potential distribution of Blumea balsamifera in China using MaxEnt and the ex situ conservation based on its effective components and fresh leaf yield

Environmental Science and Pollution Research - Blumea balsamifera is a famous Chinese Minority Medicine, which has a long history in Miao, Li, Zhuang, and other minority areas. In recent years, due...