食电微生物是如何利用电子来还原二氧化碳的?(附原文) 诸平 据美国华盛顿大学( Washington University )2019年3月22日报道,该大学的一个研究小组展示了一种名为沼泽红假单胞菌 ( Rhodopseudomonas palustris ) 的光养微生物如何从金属氧化物或铁锈等导电物质中吸收电子来还原CO 2 。位于美国圣路易斯的华盛顿大学的一项新研究解释了这样一种细胞过程,即使喜爱阳光的微生物能够“吃掉”电子,从而再将电子转移来固定CO 2 ,为其生长提供燃料。 在华盛顿大学文理学院的生物学助理教授 Arpita Bose 和她实验室的博士生 Michael Guzman 的带领下,华盛顿大学的一个研究小组展示了一种天然产生的 沼泽红假单胞菌 ( Rhodopseudomonas palustris ) 是如何从金属氧化物或铁锈等导电物质中吸收电子的。这项研究发表在3月22日的《自然通讯》杂志上 —— Michael S. Guzman, Karthikeyan Rengasamy, Michael M. Binkley, Clive Jones, Tahina Onina Ranaivoarisoa, Rajesh Singh, David A. Fike, J. Mark Meacham Arpita Bose. Phototrophic extracellular electron uptake is linked to carbon dioxide fixation in the bacterium Rhodopseudomonas palustris. Nature Communications, 2019, Volume 10, Article number: 1355. ( Published:22 March 2019 ). s41467-019-09377-6.pdf 相关视频 : https://youtu.be/z5cyX0MUAiU 这项研究建立在 Arpita Bose 之前发现的基础上,即 R. palustris TIE-1可以消耗来自锈体代理如平衡电极( poised electrodes )等的电子,这个过程被称为细胞外电子摄取。 R. palustris 是光养性的,这意味着它利用光的能量进行某些代谢过程。这项新研究解释了这种微生物将其从电中摄取的电子转移倾倒在细胞的凹陷处。 研究微生物代谢及其对生物地球化学循环影响的 Arpita Bose 说:“这第一次清楚地表明,这种活动——生物体吃电的能力——与CO 2 固定有关。”这种知识可以帮助利用微生物的自然能力进行可持续能源储存或其他生物能源应用——这一潜力已经引起了美国能源部和国防部的注意。 Arpita Bose 说:“ 在野生和异国他乡都能找到 R. palustris 这种微生物菌株,比如马萨诸塞州伍兹·霍尔 (Woods Hole, Massachusetts) 的一座锈迹斑斑的桥上就可以找到,TIE-1就是从这座桥上分离出来的。”“真的,你到处都能找到这些生物。这表明细胞外电子吸收可能非常普遍。” Michael S. Guzman 补充说:“主要的挑战为它是一种厌氧菌,所以你需要在没有氧气的环境中生长,这样它才能获得光能。但另一方面,这些挑战在这种生物体中得到了许多其他生物体所没有的多功能性的满足。” 研究人员 在他们的新论文中表述,来自电的电子进入膜中的蛋白质,这对光合作用很重要。令人惊讶的是,当他们删除了这种微生物固定 CO 2 的能力后,他们发现这种微生物消耗电能的能力下降了90%。 Arpita Bose 说: “它真的想用这个系统来固定 CO 2 ,如果你把它拿走——这种与生俱来的能力——它根本就不想占据电子了。” 她说,这种反应在某些方面类似于可充电电池。 “这种微生物利用电力为其氧化还原池充电,储存电子,使其高度还原。”“为了释放它,细胞还原了 CO 2 。所有这些的能量都来自阳光。整个过程不断重复,让细胞只用电、 CO 2 和阳光就能制造出生物分子。” 一个全华盛顿大学的团队克服了许多技术障碍完成了这项研究。来自麦凯维工程学院(McKelvey School of Engineering)的马克·米查姆(Mark Meacham)帮助设计和制造了微流体设备,使研究人员能够专注于当此菌从电源获取电子时细胞内产生的活动。该团队还依赖于包括地球和行星科学系的大卫·菲克( David Fike )在内的合作者的支持,他们帮助 Arpita Bose 和 Michael S. Guzman 使用次级离子质谱来确定微生物如何利用 CO 2 。 这项新研究回答了基础科学问题,并为未来的生物能源应用提供了大量的机会。 Michael S. Guzman 说:“很长一段时间以来,人们已经知道微生物可以与环境中类似电极的物质相互作用,也就是带电的矿物质。”“但是没有人真正理解光自养生物是如何完成这一过程的,比如这些能够固定自身碳并利用光产生能量的生物。”这项研究填补了该领域一个人们知之甚少的空白。” Arpita Bose 的实验室正致力于利用这些微生物制造生物塑料和生物燃料。 Arpita Bose 说:“我们希望,将电力和照明结合起来减少CO 2 排放的能力,可能有助于为能源危机找到可持续的解决方案。” 更多信息请注意浏览相关报道或者原文 A shocking diet: Researchers describe microbe that 'eats' electricity ; Study shows how electricity-eating microbes use electrons to fix carbon dioxide Abstract Extracellular electron uptake (EEU) is the ability of microbes to take up electrons from solid-phase conductive substances such as metal oxides. EEU is performed by prevalent phototrophic bacterial genera, but the electron transfer pathways and the physiological electron sinks are poorly understood. Here we show that electrons enter the photosynthetic electron transport chain during EEU in the phototrophic bacterium Rhodopseudomonas palustris TIE-1. Cathodic electron flow is also correlated with a highly reducing intracellular redox environment. We show that reducing equivalents are used for carbon dioxide (CO 2 ) fixation, which is the primary electron sink. Deletion of the genes encoding ruBisCO (the CO 2 -fixing enzyme of the Calvin-Benson-Bassham cycle) leads to a 90% reduction in EEU. This work shows that phototrophs can directly use solid-phase conductive substances for electron transfer, energy transduction, and CO 2 fixation.
据来自 哥德斯密特大会( Goldschmidt Conference )的消息,科学家发现了可以除去大气中CO 2 的成矿方法,更多信息请浏览原文: Scientists find way to make mineral which can remove CO 2 from atmosphere August 14, 2018, Goldschmidt Conference Natural magnesite crystal (4 microns wide). Credit: Ian Power Scientists have found a rapid way of producing magnesite, a mineral which stores carbon dioxide. If this can be developed to an industrial scale, it opens the door to removing CO 2 from the atmosphere for long-term storage, thus countering the global warming effect of atmospheric CO 2 . This work is presented at the Goldschmidt conference in Boston. Scientists are already working to slow global warming by removing carbon dioxide from the atmosphere, but there are serious practical and economic limits on developing the technology. Now, for the first time, researchers have explained how magnesite forms at low temperature, and offered a route to dramatically accelerating its crystallization. A tonne of naturally-occurring magnesite can remove around half a tonne of CO 2 from the atmosphere, but the rate of formation is very slow. Project leader, Professor Ian Power (Trent University, Ontario, Canada) said: Our work shows two things. Firstly, we have explained how and how fast magnesite forms naturally. This is a process which takes hundreds to thousands of years in nature at Earth's surface. The second thing we have done is to demonstrate a pathway which speeds this process up dramatically The researchers were able to show that by using polystyrene microspheres as a catalyst, magnesite would form within 72 days. The microspheres themselves are unchanged by the production process, so they can ideally be reused. Using microspheres means that we were able to speed up magnesite formation by orders of magnitude. This process takes place at room temperature, meaning that magnesite production is extremely energy efficient Magnesite sediments in a playa in British Columbia, Canada. Credit: Ian Power For now, we recognise that this is an experimental process, and will need to be scaled up before we can be sure that magnesite can be used in carbon sequestration (taking CO 2 from the atmosphere and permanently storing it as magnesite). This depends on several variables, including the price of carbon and the refinement of the sequestration technology, but we now know that the science makes it do-able. Commenting, Professor Peter Kelemen at Columbia University's Lamont Doherty Earth Observatory (New York) said It is really exciting that this group has worked out the mechanism of natural magnesite crystallization at low temperatures, as has been previously observed—but not explained—in weathering of ultramafic rocks. The potential for accelerating the process is also important, potentially offering a benign and relatively inexpensive route to carbon storage, and perhaps even direct CO 2 removal from air. Explore further: Scientists probe abandoned mine for clues about permanent CO2 sequestration
h-BN 泡沫吸收 C O 2 , 循环 2000 次,吸附量 340%(附原文) 诸平 据物理学家组织网( Phys.org ) 2017年8月16日转载美国化学会主办的杂志 ACS Nano 的消息,美国赖斯大学( Rice University )的科学家研究发现,氮化硼( boron nitride) 泡沫可以吸收CO 2 ,图1就是用聚乙烯醇进行处理之后的六方氮化硼 ( hexagonal- boron nitride简称h-BN)的 泡沫块,已经证明它能够吸附其自身 重量三倍多的CO 2 。 Fig. 1 Blocks of hexagonal-boron nitride foam treated with polyvinyl alcohol proved able to adsorb more than three times its weight in carbon dioxide. The reusable material was created at Rice University. Credit: Ajayan Research Group/Rice University 美国 赖斯大学的材料科学家已经从二维六方氮化硼( h-BN )薄片 创造出 一种可以吸收CO 2 的轻 泡沫。 他们发现冻干的h-BN在液体中分解后可以将其转变成大规模的泡沫。 但是向混合物中添加少量的聚乙烯醇( polyvinyl alcohol简称 PVA)之后,可以使其转变为一种更稳定和更有用的材料。根据赖斯大学进行此项研究的 材料科学家 普里克尔·阿杰安( Pulickel Ajayan )的介绍,此种 泡沫具有高度多孔,而且其属性可以 进行 调控,可以应用于 空气过滤器以及作为 气体吸收 材料。相关研究结果于2017年8月3日已经 在美国化学学会主办的杂志 ACS Nano 网站上发表—— Peter Samora Owuor , Ok-Kyung Park , Cristiano F. Woellner , Almaz S. Jalilov , Sandhya Susarla , Jarin Joyner , Sehmus Ozden , LuongXuan Duy , Rodrigo Villegas Salvatierra , Robert Vajtai , James M. Tour , Jun Lou , Douglas Soares Galvão , Chandra Sekhar Tiwary , Pulickel M. Ajayan . Lightweight Hexagonal Boron Nitride Foam for CO 2 Absorption .(点击可以下载原文) ACS Nano , Publication Date (Web): August 3, 2017 . DOI: 10.1021/acsnano.7b03291 . 参加此项研究的除了美国赖斯大学化学系、材料科学与纳米工程系的研究人员之外,还有韩国全北国立大学( Chonbuk National University )、美国洛斯阿拉莫斯国家实验室( Los Alamos National Laboratory )以及巴西 坎皮纳斯州立大学( State University of Campinas )的科学家。研究者指出, 聚乙烯醇在其中的作用其实就是一种粘合剂,它被加入到含有 h-BN薄片的溶液中进行混合,当将混合液 冻干时,聚乙烯醇与 h-BN微片 结合自排列成一种格子。此 步过程是可拓展的。此项研究的合作者、也是美国赖斯大学的 博士后研究者 钱德拉·谢卡尔·特瓦利( Chandra Sekhar Tiwary)说: “即使少量PVA发挥作用,也 有助于使 h-BN薄片之间连接在一起而导致 泡沫变得僵硬起来,但是,其 表面积并未受到影响, 几乎没有丝毫改变。” 在 分子动力学模拟( molecular dynamics simulations )过程 中,此泡沫会吸附其自身重量的340%的CO 2 。被吸附的CO 2 气体可以通过蒸发使其从吸附材料中解析出来,此吸附材料可以多次重复使用。 压缩试验结果表明,反复使用2000次此泡沫竟然变得更加坚硬。 Fig. 2 A microscope image shows the high surface area of hexagonal-boron nitride foam glued together with polyvinyl alcohol. The tough, light foam can be used to soak up carbon dioxide or as a material to shield biological tissues from lasers. Credit: Ajayan Research Group/Rice University 图2是显微镜图像显示出h-BN 泡沫 与聚乙烯醇粘在一起 的高表面积。 这种坚硬的、轻型泡沫可以用 来吸收CO 2 或作为一种材料来保护生物组织不受激光的影响。当采用另一种聚合物即 聚二甲基硅氧烷(Polydimethylsiloxane简称 PDMS)进行涂饰时,此 泡沫 成为一种有效的保护材料,可以免遭激光影响,因此它可以用于生物医学、电子产品以及一些其他应用。 最终,研究人员想要控制材料孔的大小,以便适宜于特定的应用,如从水中分离油品。 模拟工作是由合著者、巴西 坎皮纳斯州立大学 和美国赖斯大学 联合培养的 博士后研究者 克里斯蒂亚诺 ·沃尔勒( Cristiano Woellner )作为模拟实验的指导。 克里斯蒂亚诺 ·沃尔勒 说:“实验与理论计算相结合对于了解h-BN与粘合剂组成 的力学响应 是非常 重要的,通过模拟可以是实验研究者 提前了解他们将如何对其混合体系进行改进。” Fig.3 A molecular dynamics simulation shows polyvinyl alcohol molecules of carbon (teal), oxygen (red) and hydrogen (white) binding two-dimensional sheets of hexagonal-boron nitride (blue and yellow). The reusable material created at Rice University can sequester more than three times its weight in carbon dioxide. Credit: Ajayan Research Group/Rice University 图3的分子动力学模拟结果显示,聚乙烯醇分子的碳(青色)、氧(红色)和氢(白色)与h-BN( 蓝色和黄色 )的二维薄片结合在一起 。莱斯大学创建的可重用的材料可以吸收CO 2 ,吸附量使其吸附材料自重的三倍多。更多信息请注意浏览原文或者相关其他报道。 Graphene foam gets big and tough: Nanotube-reinforced material can be shaped, is highly conductive Boron nitride foam soaks up carbon dioxide Abstract Weak van der Waals forces between inert hexagonal boron nitride (h-BN) nanosheets make it easy for them to slide over each other, resulting in an unstable structure in macroscopic dimensions. Creating interconnections between these inert nanosheets can remarkably enhance their mechanical properties. However, controlled design of such interconnections remains a fundamental problem for many applications of h-BN foams. In this work, a scalable in situ freeze-drying synthesis of low-density, lightweight 3D macroscopic structures made of h-BN nanosheets chemically connected by poly(vinyl alcohol) (PVA) molecules via chemical cross-link is demonstrated. Unlike pristine h-BN foam which disintegrates upon handling after freeze-drying, h-BN/PVA foams exhibit stable mechanical integrity in addition to high porosity and large surface area. Fully atomistic simulations are used to understand the interactions between h-BN nanosheets and PVA molecules. In addition, the h-BN/PVA foam is investigated as a possible CO 2 absorption and as laser irradiation protection material. Keywords: CO 2 absorption ; h-BN ; MD simulation ; PVA ; three-dimensional materials
Nat.: 铁 催化 + 阳光将 CO 2 转化为甲烷 诸平 前文 介绍了将CO 2 转化为碳纳米管的新技术 —— 清理 CO 2 排放可创造价值数十万亿美金的利润 。 本文再介绍来自 《自然》( Nature )杂志网站的另一则新成果。 法国( Université Paris Diderot )和阿根廷( Universidad Nacional de Córdoba , Argentina )的研究人员合作,利用铁配合物(作为催化剂)和太阳光可以将 CO 2 转化为甲烷。详见 Heng Rao , Luciana C. Schmidt , Julien Bonin , Marc Robert . Visible-light-driven methane formation from CO 2 with a molecular iron catalyst . Nature , 2017 , DOI: 10.1038/nature23016 . 图 1 就是来自《自然》杂志发表的论文中 利用铁化合物(作为催化剂)和太阳光可以将 CO 2 转化为甲烷 机理图示。 Fig. 1 Sketch of the proposed mechanism for CO 2 reduction to CH 4 by catalyst 1. Credit: Nature (2017). DOI: 10.1038/nature23016 来自 法国巴黎狄德罗大学 ( Université Paris Diderot ) 和 来自 阿根廷 的 科尔多瓦 国立大学( Universidad Nacional de Córdoba ) 研究 人员合作,已经 发现 了一种 可以用来将 CO 2 转换成甲烷 的化学 反应过程。他们的论文 于 2017 年 7 月 17 日已 在《自然》杂志 网站 上 发表 , 该 研究小组描述了他们的技术是怎样工作的 以及 他们 对其进行改进 的 一些 想法。 随着人类 的 活动 持续 不断 地向 大气中引入 CO 2 , 导致 全球变暖 , 世界各地的科学家寻求替代方法来减少 CO 2 气体 的 排放 ,并设法降低大气中已经存在的 CO 2 含量 。在 法国和阿根廷科学家联合完成的 这 项 新 研究中 , 研究人员已经开发出一种化学过程 , 此化学过程具有一箭双雕的作用,不仅可以减少 CO 2 排放, 同时 也可以降低现有大气中 CO 2 的水平,使其 转化为可以 作为 绿色能源 使用的 甲烷 。 此 技术 涉及到对于 CO 2 乙腈 ( CH 3 CN )溶液 的 照射, CH 3 CN 具有 可以提供的 单电子 , 一种 光敏剂和 一种四苯基铁 卟啉 配合物( iron tetraphenylporphyrin ) 催化剂 。此 铁 配合物是用 四苯基卟啉 基团功能化的一种配合物 。被阳光照射持续几个小时,此过程会导致甲烷(CH 4 )、 CO及 H 2 产生 。 研究人员承认 , 这个过程是非常低效的 , 因为生产 的 产品 中 实际上CO 含量占 82% 。 而且此过程 也非常慢 , 产生 CH 4 的速度为 12 g/h 。但是 该研究 团队认为 , 使用修改后的两步过程 即可得到 更高效 率 。 研究人员指出 , 他们还使用纯洁 的 CO 2 进行了相关 研究。 研究 团队还计划更好地了解 在反应过程中 实际究竟发生了 什么反应,他们 知道 在此 过程 的 第一 步就是 铁 与 CO 2 结合 , 但它 究竟是如何 发生加氢 反应的 仍然 并 不清楚。 更多信息请注意浏览原文或者相关报道 Converting carbon dioxide to methane using iron and sunlight New photocatalyst speeds up the conversion of carbon dioxide into chemical resources Abstract Converting CO 2 into fuel or chemical feedstock compounds could in principle reduce fossil fuel consumption and climate-changing CO 2 emissions. One strategy aims for electrochemical conversions powered by electricity from renewable sources, but photochemical approaches driven by sunlight are also conceivable. A considerable challenge in both approaches is the development of efficient and selective catalysts, ideally based on cheap and Earth-abundant elements rather than expensive precious metals. Of the molecular photo- and electrocatalysts reported, only a few catalysts are stable and selective for CO 2 reduction; moreover, these catalysts produce primarily CO or HCOOH, and catalysts capable of generating even low to moderate yields of highly reduced hydrocarbons remain rare. Here we show that an iron tetraphenylporphyrin complex functionalized with trimethylammonio groups, which is the most efficient and selective molecular electro- catalyst for converting CO 2 to CO known, can also catalyse the eight-electron reduction of CO 2 to methane upon visible light irradiation at ambient temperature and pressure. We find that the catalytic system, operated in an acetonitrile solution containing a photosensitizer and sacrificial electron donor, operates stably over several days. CO is the main product of the direct CO 2 photoreduction reaction, but a two-pot procedure that first reduces CO 2 and then reduces CO generates methane with a selectivity of up to 82 per cent and a quantum yield (light-to-product efficiency) of 0.18 per cent. However, we anticipate that the operating principles of our system may aid the development of other molecular catalysts for the production of solar fuels from CO 2 under mild conditions.
JACS: 化学家创建分子“叶片”,将 CO 2 有效 转化为 CO(附原文) 诸平 据物理学家组织网( Phys.org )2017年3月8日报道,美国印第安纳大学( Indiana University )的化学家已经创建了一种分子“叶片”,其功能像普通的植物叶片一样,利用太阳光就可以将大气中的温室效应气体CO 2 ,转化为具有广泛应用前景的CO。众所周知,CO被氧化形成CO 2 会产生大量的能力,而要想将CO 2 再转化为CO同样需要大量能量,然而,植物叶片的光合作用则轻而易举地将 CO 2 还原为CO,并释放出氧气。 印第安纳大学( Indiana University )的 乔潇潇(Xiaoxiao Qiao音译)等人,他们利用纳米石墨烯-铼(Re)形成的配合物 分子与二吡啶(bipyridine)连接,可以使 CO 2 的还原反应高效顺利进行,将其转换成CO 。其实, 此“叶片”主要由2部分组成,其中纳米石墨烯部分就是太阳能捕获器,吸收太阳能;而其中的 铼 原子就是产生CO的“引擎”。纳米石墨烯捕获到的太阳能来驱动 铼 原子 的 电子 流向CO 2 ,使其转化为稳定的CO。更多信息请浏览下面的相关报道或者浏览原文。 Chemists create molecular 'leaf' that collects and stores solar power without solar panels March 8, 2017 An international team of scientists led by Liang-shi Li at Indiana University has achieved a new milestone in the quest to recycle carbon dioxide in the Earth's atmosphere into carbon-neutral fuels and others materials. The chemists have engineered a molecule that uses light or electricity to convert the greenhouse gas carbon dioxide into carbon monoxide —a carbon-neutral fuel source—more efficiently than any other method of carbon reduction. The process is reported today in the Journal of the American Chemical Society . If you can create an efficient enough molecule for this reaction, it will produce energy that is free and storable in the form of fuels, said Li, associate professor in the IU Bloomington College of Arts and Sciences' Department of Chemistry. This study is a major leap in that direction. Burning fuel—such as carbon monoxide—produces carbon dioxide and releases energy. Turning carbon dioxide back into fuel requires at least the same amount of energy. A major goal among scientists has been decreasing the excess energy needed. This is exactly what Li's molecule achieves: requiring the least amount of energy reported thus far to drive the formation of carbon monoxide. The molecule—a nanographene-rhenium complex connected via an organic compound known as bipyridine—triggers a highly efficient reaction that converts carbon dioxide to carbon monoxide. The ability to efficiently and exclusively create carbon monoxide is significant due to the molecule's versatility. Carbon monoxide is an important raw material in a lot of industrial processes, Li said. It's also a way to store energy as a carbon-neutral fuel since you're not putting any more carbon back into the atmosphere than you already removed. You're simply re-releasing the solar power you used to make it. The secret to the molecule's efficiency is nanographene—a nanometer-scale piece of graphite, a common form of carbon (i.e. the black lead in pencils)—because the material's dark color absorbs a large amount of sunlight. Li said that bipyridine-metal complexes have long been studied to reduce carbon dioxide to carbon monoxide with sunlight. But these molecules can use only a tiny sliver of the light in sunlight, primarily in the ultraviolet range, which is invisible to the naked eye. In contrast, the molecule developed at IU takes advantage of the light-absorbing power of nanographene to create a reaction that uses sunlight in the wavelength up to 600 nanometers—a large portion of the visible light spectrum. Essentially, Li said, the molecule acts as a two-part system: a nanographene energy collector that absorbs energy from sunlight and an atomic rhenium engine that produces carbon monoxide. The energy collector drives a flow of electrons to the rhenium atom, which repeatedly binds and converts the normally stable carbon dioxide to carbon monoxide. The idea to link nanographene to the metal arose from Li's earlier efforts to create a more efficient solar cell with the carbon-based material. We asked ourselves: Could we cut out the middle man—solar cells—and use the light-absorbing quality of nanographene alone to drive the reaction? he said. Next, Li plans to make the molecule more powerful, including making it last longer and survive in a non-liquid form, since solid catalysts are easier to use in the real world. He is also working to replace the rhenium atom in the molecule—a rare element—with manganese, a more common and less expensive metal. Explore further: Scientists solve puzzle of converting gaseous carbon dioxide to fuel More information: Xiaoxiao Qiao, Qiqi Li, Richard N. Schaugaard, Benjamin W. Noffke, Yijun Liu , Dongping Li, Lu Liu, Krishnan Raghavachari , and Liang-shi Li. Well-Defined Nanographene–Rhenium Complex as an Efficient Electrocatalyst and Photocatalyst for Selective CO 2 Reduction (点击可以免费下载原文) . Journal of the American Chemical Society . (2017). DOI:10.1021/jacs.6b12530 Abstract Improving energy efficiency of electrocatalytic and photocatalytic CO 2 conversion to useful chemicals poses a significant scientific challenge. We report on using a colloidal nanographene to form a molecular complex with a metal ion to tackle this challenge. In this work, a well-defined nanographene–Re complex was synthesized, in which electron delocalization over the nanographene and the metal ion significantly decreases the electrical potential needed to drive the chemical reduction. We show the complex can selectively electrocatalyze CO 2 reduction to CO in tetrahydrofuran at −0.48 V vs NHE, the least negative potential reported for a molecular catalyst. In addition, the complex can absorb a significant spectrum of visible light to photocatalyze the chemical transformation without the need for a photosensitizer.
This ClimateWire story was sent to you by: cliu.info@gmail.com Personal message: Dear Prof. Jiang -- Thanks again for your kind support. Please see the organic farming story below. Looking forward to learn your new studies on climate change issue in the future. All the best, Coco AN EE PUBLISHING SERVICE AGRICULTURE: Organic farming will help China cut emissions without compromising crop production -- study Coco Liu, EE Asia correspondent Published: Monday, May 11, 2015 HONG KONG -- Agriculture is known as a major contributor to greenhouse gas emissions, but a new study finds that organic farming can reverse the agriculture ecosystem from a carbon source to a carbon sink. In a paper published in Science Bulletin , a group of scientists estimated that more than 1 billion tons of excess carbon dioxide can be stored in China's farmlands annually through regenerative organic farming, ranching and land use. Meanwhile, crop yields can also increase as the soil fertility is improved by the use of organic manure. To mitigate greenhouse gas emissions and retain soil fertility, organic agriculture might be a wise choice for decreasing the intensive use of synthetic fertilizers, protecting environments, and further improving crop yields, the scientists said. They demonstrated how to do so by integrating organic farming with cattle breeding in a rural area of eastern China's Shandong province. The majority of nutrient inputs in farmlands there traditionally came from chemical fertilizer. During the experimental run, the scientists fed cattle with crop residues, collected and composted cattle manure, and used it to replace chemical fertilizer for crop production. The study's finding shows that although cattle breeding causes higher emissions of methane and other type of greenhouse gases, the new practice still sequesters more carbon, thanks to crop residue recycling and chemical reduction. Putting that into numbers, the study notes, farmlands using cattle manure absorb greenhouse gas emissions equivalent to 8.8 tons of carbon dioxide per hectare every year. By contrast, the farmland using chemical fertilizer releases greenhouse gas emissions equivalent to 2.7 tons of carbon dioxide. Besides that, turning crop residues into animal feed helps make full use of agricultural waste. According to the scientists' estimation, China produces about 630 million tons of crop residues annually, with more than two-thirds of them being abandoned or burned -- causing air pollution and driving up greenhouse gas emissions. World's biggest agricultural emitter has options Unlike ranchers in Brazil who have cleared forests to build facilities for cattle, most farmers in eastern China enclose part of their existing agricultural land as cattle pasture. As a result, emissions from land-use change are barely a concern there. A 2011 report from the Food and Agriculture Organization of the United Nations says that agriculture causes about one-third of global greenhouse gas emissions when direct energy use; emissions from livestock; the production of fertilizers, pesticides, machinery and equipment; as well as soil degradation and land-use change for feed production are taken into account. An analysis by the Washington, D.C.-based think tank World Resources Institute shows that in 2011, China generated more agriculture-related emissions than any other nation. Jiang Gaoming, one of the study's authors and a professor at the Chinese Academy of Sciences' Institute of Botany, said that using organic manure can significantly reduce greenhouse gas emissions from crop production. If the country completely replaces chemical fertilizer with organic manure, the potential should be 1.38 billion tons of carbon dioxide for the whole China's farmland per year, Jiang said. However, there are barriers to making such a switch. For one, according to Jiang, farms in China are reluctant to use organic fertilizer as this requires more labor, and labor costs have increased greatly in recent years. In addition, the country may not be able to find enough organic fertilizer to use if all the farmlands are replaced with organic fertilizer, Jiang said. Jiang and his team suggested that the Chinese government could encourage farmers to use half the amount of chemical fertilizer while the rest is replaced with organic ones. A combination of organic manure and chemical fertilizer demonstrated the best result in improving soil quality and crop yields, while decreasing greenhouse gas emissions, the scientists said. Want to read more stories like this? Click here to start a free trial to EE -- the best way to track policy and markets. ABOUT CLIMATEWIRE – The politics and business of climate change ClimateWire is written and produced by the staff of EE Publishing, LLC. It is designed to provide comprehensive, daily coverage of all aspects of climate change issues. From international agreements on carbon emissions to alternative energy technologies to state and federal GHG programs, ClimateWire plugs readers into the information they need to stay abreast of this sprawling, complex issue.
Louis Agassiz James D. Dana 17世纪,欧洲大陆和英国地表的松散堆积是和诺亚洪水完美交织在一起的。一直到18世纪末,苏格兰的James Hutton在其著作中提到,源自阿尔卑斯的冰川可能是砾石到处散落的推手,但认为气候没有变化,只是阿尔卑斯山更高而已。 现代意义上的冰期思想是由瑞士Louis Agassiz提出的。这位也是个传奇。职业生涯初期因为研究鱼类化石成为第三位Wollaston Medal得主(1836)。获得奖章的第二年的夏天,30岁的Agassiz在一个会议论文中提出了冰期思想,并随后进行全面论述:我们生活在相对温暖的时期,但地球温度曾经反复波动,更冷的气候可能再次来临。冰期学说解释了欧洲普遍存在的漂砾、冰碛,预言了欧洲北部存在统一的冰盖。1840年,他在格拉斯哥的会议上遇见了Lyell,当时Lyell还主张均变论观点。在苏格兰的野外工作中Agassiz向Lyell等介绍冰蚀地貌和冰川作用的微观证据,促使Lyell接受了冰期思想。再后来,1846年,Agassiz前往美国,作为博物学家在康奈尔和哈佛终老。不足10年,他就开创了一个让无数后来者呕心沥血的方向。 很快,探索冰期成因走上历史舞台。1842年,有两件事对后来影响深远。法国Adhémar尝试用岁差解释冰期成因,美国MacLaren在介绍Agassiz的冰期理论时提出冰川对海平面的影响,——它们分别成为后来轨道尺度Milankovitch假说和构造尺度抬升-风化假说的源头。 今年的Wollaston Medal得主Maureen Raymo在这两个方向上都有杰出表现。 。今天的Science文章对她的抬升-风化理论是一个有力补充,重点说这个。 在美国东部阿巴拉契亚造山带的研究中,已经注意到海平面(侵蚀基准面)变化(Suess 1883)以及地壳均衡(Hall 1857)反弹之间复杂的联系。James D. Dana(1856)首先注意到了构造抬升和 CO 2 消耗的关系。北美四次冰期证据的发现者、USGS负责人Thomas Chamberlin(1898, 1899)结合沉积证据,将碳循环与冰期旋回联系起来。 20世纪的前80年里,横扫全球四次冰期从1955年开始多旋回理论所取代,地球轨道影响冰期的Milankovitch假说从理论走向实证。但构造尺度上,冰期成因似乎毫无进展。 历史在召唤。
记得上几周我在温景嵩老师的博文“退休之乐(5):亮出了批判IPCC错误论断的旗帜”评论里面支持全球变暖,温老师举了北大钱维宏教授得到的一个例子,认为“在年际和年代际的气温实际变化和人类活动排放出的二氧化碳的实际变化呈现出一种反相关的关系”,后来我去查看cctv2“面对面”对钱教授的采访,好像是举得1970年到2000年的温度数据(具体忘了,差不多这么多)。我现在说的这篇文章,恰好可以部分解释这个反例。 这篇我们组的题为“ The Hindcast Skill of the CMIP Ensembles for the Surface Air Temperature Trend ”( http://www.agu.org/pubs/crossref/2012/2012JD017765.shtml )的文章刚刚发表在JGR-Atmospheres上,论文的第一作者Koichi(和我合作了两篇文章,还未发表)分析了大概50个IPCC的实验结果,从不同时间(10年~100年)和空间(10°到半球尺度)尺度分析了模式对过去温度趋势的模拟能力,结果证明在洲际以上地理尺度和30年以上的时间尺度上模式表现出了很好的模拟能力,但在地区尺度和时间小于30年的范围内,模式的结果不是很可靠(相关报道见 http://uanews.org/story/ua-climate-scientists-put-predictions-test )。 回到最开始的争论,钱老师的结果是正确的,前提是在一定的时空尺度下。现在IPCC的实验大概都是30年到100年(或者300年)尺度,虽然CO 2 导致的增温的强度不可能十分精确,但是模式告诉我们地球在未来100年在CO 2 增长的情况下的确会变暖,即使某些地区某个时间段(小于30年)会呈现出降温的趋势。
It's only 73F in my living room at 7:23 am. I have to put socks on. So, I would say it's a cold winter day in Hawaii. However, I will never agree with those people who think burning oil, gas, and coal is ok. It is NOT ok. One third of the CO2 we release into the atmosphere is absorbed by the world ocean. So, the ocean is becoming more acid. Read about ocean acidification, and you will be as worried as most oceanographers about the future of the Earth.
3 June 2011 | By Stephen Harris Carbon dioxide is bad. That’s the common thread in public discourse. We’re constantly told of the need to reduce the amount of CO2 in the atmosphere and that it’s destroying the planet. Of course the reality is that carbon dioxide is a key part of the natural cycle of energy and vital to the survival of all life on this planet. It also has a wide range of commercial uses. So should we see CO2 as more of a resource than a problem? Our supplies of the gas are set to increase massively as carbon-capture power plants become a reality, and scientists and industry are increasingly looking for new ways to use and hopefully monetise it. Carbon dioxide is already used in food preparation and preservation, in drug and chemical processing, in water treatment, welding and pneumatics. None of these applications will soak up all the CO2 we’re going to produce in the next fifty years, though at least CCS power stations could become more cost-effective if they sell the gas on. But what if we could develop a use for carbon dioxides that actually helped the climate change cause and made a big impact on greenhouse gas emissions? Injecting CO2 into oil wells as they dry up keeps it out of the atmosphere but also helps get more oil out, meaning we have more fossil fuels to burn and even more CO2 to deal with. A different idea, as highlighted in our recent feature , is to mineralise CO2 to create products for use in the construction and food industries. If we can make it economical and energy efficient, we could even take the waste materials of existing cement-making processes – ash and carbon dioxide – and combine them to make a stronger form of cement. Nature, as so often is the case, could also provide a solution – photosynthesis. It gives plants their own wonderful use for CO2, but unless we literally go back to living in forests by covering the whole world in trees, there’s really only so much they can do for us. Instead, some scientists are hoping to deliver an artificial version of photosynthesis that effectively turns carbon dioxide into an energy storage medium. If we can efficiently use sunlight to power the reaction, we can transform the pesky gas (and water) into usable fuels. Of course, we are already turning plants into fuel with serious consequences for food prices. Around 40 per cent of corn grown in the US is now used to make ethanol instead of feeding humans and animals, according to the Department of Agriculture. Photosynthesising algae could provide one alternative to this. Another idea is to do the energy conversion ourselves. Scientists at MIT have already developed a ‘practical artificial leaf’ that uses solar energy and inexpensive catalysts to produce hydrogen from water with efficiencies much greater than those of real leaves. Find a way of efficiently adding carbon dioxide to this artificial process and we could create biofuels to use in our existing fuel infrastructure without the need to rely on growing plants (and impacting food production). Though all these ideas are still at the laboratory stage, the business world is taking notice. Spanish research institute MATGAS, which is majority-owned by industrial gas company Air Products, is coming to the end of a Though all these ideas are still at the laboratory stage, the business world is taking notice. Spanish research institute MATGAS, which is majority-owned by industrial gas company Air Products, is coming to the end of a
Ward began to study the effects of rising carbon dioxide levels on plant physiology and development as a graduate student at Duke University with Boyd Strain. “We would expose plants to high CO2 and measure what happened. CO2 is the substrate for photosynthesis, so with high CO2 you often see stimulation of photosynthesis and reproduction. But we also know that in the field, rising CO2 also causes warming. And as you warm plants up, they have higher respiration rates, which can actually reduce some of the gain in carbon they accumulated from the high carbon dioxide.” So the effects of CO2 can be positive and negative—and even unexpected. Ward conducted a study to examine how plants might evolve to adapt to conditions of elevated CO2. She grew Arabidopsis in concentrations of CO2 that were either as high as predicted for the future or as low as has been measured in the past. She then selected and bred the individuals that produced the most seeds. After five generations, she found that the plants that were most fecund under high-CO2 conditions had sped up their life cycle. As a result, they actually produced less biomass than plants that were picked from the population at random. “That was not what I expected,” says Ward. “I thought that plants selected for high seed number under high CO2 would be much larger. But they weren’t. That suggests that genetic change is possible even in a relatively short amount of time —and that the way plants respond to rising CO2 can be surprising.” Read more: Harvesting Ideas - The Scie ntist - Magazine of the Life Sciences http://www.the-scientist.com/article/display/58072/#ixzz1K6zSxO28
GRL Eitors Highlight Temporary acceleration of the hydrological cycle in response to a CO2 rampdown Peili Wu Met Office Hadley Centre, Exeter, UK Richard Wood Met Office Hadley Centre, Exeter, UK Jeff Ridley Met Office Hadley Centre, Exeter, UK Jason Lowe Met Office Hadley Centre, Exeter, UK Current studies of the impact of climate change mitigation options tend to scale patterns of precipitation change linearly with surface temperature. Using climate model simulations, we show a nonlinear hydrological response to transient global warming and a substantial side effect of climate mitigation. In an idealised representation of mitigation action, where we reverse the trend of global warming, the precipitation response shows significant hysteresis behaviour due to heat previously accumulated in the ocean. Stabilising or reducing CO2 concentrations in the atmosphere is found temporarily to strengthen the global hydrological cycle, while reducing rainfall over some tropical and subtropical regions. The drying trend under global warming over The Amazon, Australia and western Africa may intensify for decades after CO2 reductions. The inertia due to accumulated heat in the ocean implies a commitment to hydrological cycle changes long after stabilisation or reduction of atmospheric CO2 concentration. Received 26 April 2010; accepted 17 May 2010; published 23 June 2010. Citation: Wu, P., R. Wood, J. Ridley, and J. Lowe (2010), Temporary acceleration of the hydrological cycle in response to a CO2 rampdown, Geophys. Res. Lett., 37, L12705, doi:10.1029/2010GL043730.
Steven D. Allison, Matthew D. Wallenstein, Mark A. Bradford. Soil-carbon response to warming dependent on microbial physiology . Nature Geoscience , 2010; DOI: 10.1038/ngeo846 全球变暖的情况下,微生物的生理活动可能决定了土壤中向大气释放CO2的量。 多数生态系统模型都预测,随着全球温度的升高将会刺激微生物对土壤C的分解活动,从而形成一个正反馈。但是来自UC Irvine, Colorado State University and the Yale School of Forestry Environmental Studies 等单位的科学家发现随着全球温度的升高,土壤微生物在将土壤中的C转变为CO2的过程的效率将随时间的推移而降低。 以前的模型中都没有考虑到酶的活性的问题,而这些研究者的模型中考虑了酶活性在温度升高过程的变化情况。微生物产生的酶在土壤有机碳转变为CO2的过程中发挥着重要作用。