滨海盐沼湿地有机碳的沉积与埋藏研究进展

滨海盐沼湿地有着较高的碳沉积速率和固碳能力,在缓解全球变暖方面发挥着重要作用,而盐渍土壤是滨海盐沼湿地碳收支研究中最大的有机碳库,研究其碳沉积与埋藏对于理解滨海湿地碳收支有着重要的意义.本文从滨海盐沼湿地土壤有机碳的来源、土壤有机碳库与沉积速率、盐沼湿地有机碳的埋藏机制、全球变化与滨海盐沼湿地碳封存等几方面对滨海盐沼湿地有机碳沉积与埋藏的相关研究进行综述.今后研究应侧重:1)加强对控制滨海盐沼湿地碳储存变异的基本因素的进一步研究;2)对测量滨海盐沼湿地沉积物碳储量和沉积碳埋藏速率的方法进行标准化;3)对潮汐影响下滨海盐沼湿地碳与邻近生态系统之间的横向交换通量进行量化;4)探明全球变暖的影响和生产力的提高是否可以抵消因呼吸增强而造成的有机碳降解速率的升高.确定固碳速率变化驱动因子,理解气候变化和人类活动对碳埋藏的影响机制,有助于提升我国滨海盐沼湿地的固碳能力.     

重金属污染对珠江口红树林表层沉积物碳含量的影响

湿地沉积物是红树林生态系统中重要的组成部分,其总有机碳储量的变化对红树林生态系统的固碳能力有着重要影响。现有对红树林湿地重金属的研究多集中于污染评价,鲜有涉及重金属含量对沉积物总有机碳（TOC）含量影响的研究。于2018-2019年期间4次前往珠江口典型红树林湿地,采集了0-30 cm表层土壤沉积物的样品,并测定其重金属含量和TOC含量,以探讨重金属含量变化对TOC的影响。结果表明,与广东地区的背景值相比,研究区沉积物重金属含量超标较为严重,重金属来源应是人类活动;沉积物的重金属含量能够显著影响TOC含量（P<0.01,R²=0.39）,间接对红树林湿地的固碳能力、甚至全球变暖产生一定影响;Cd、As、Zn含量高的沉积物环境有利于TOC的积累,Cu、Cr、Ni、Hg含量低的沉积物环境则不利于TOC的积累。沉积物的重金属对TOC的影响的机制是非常复杂的,它们可以通过影响土壤结构、土壤化学组分、土壤内微生物、上部植被群落的生长以及凋落物归还等一系列过程,导致沉积物TOC和固碳能力的变化。     

滨海盐沼湿地有机碳的沉积与埋藏研究进展

滨海盐沼湿地有着较高的碳沉积速率和固碳能力,在缓解全球变暖方面发挥着重要作用,而盐渍土壤是滨海盐沼湿地碳收支研究中最大的有机碳库,研究其碳沉积与埋藏对于理解滨海湿地碳收支有着重要的意义.本文从滨海盐沼湿地土壤有机碳的来源、土壤有机碳库与沉积速率、盐沼湿地有机碳的埋藏机制、全球变化与滨海盐沼湿地碳封存等几方面对滨海盐沼湿地有机碳沉积与埋藏的相关研究进行综述.今后研究应侧重:1)加强对控制滨海盐沼湿地碳储存变异的基本因素的迸一步研究;2)对测量滨海盐沼湿地沉积物碳储量和沉积碳埋藏速率的方法进行标准化;3)对潮汐影响下滨海盐沼湿地碳与邻近生态系统之间的横向交换通量进行量化;4)探明全球变暖的影响和生产力的提高是否可以抵消因呼吸增强而造成的有机碳降解速率的升高.确定固碳速率变化驱动因子,理解气候变化和人类活动对碳埋藏的影响机制,有助于提升我国滨海盐沼湿地的固碳能力.     

红树林湿地碳储量及碳汇研究进展

红树林是生长在热带和亚热带地区潮间带的特殊的湿地森林,在防风固田、促进淤泥沉积、抵御海啸和台风等自然灾害和保护海岸线方面起着重要的作用.全球约有红树林152000 km²,占陆地森林面积的0.4%,我国约有230 km².热带红树林湿地的碳储量平均高达1023 Mg C·hm^-2,全球红树林湿地的碳汇能力在0.18～0.228 Pg C·a^-1.影响红树林碳储量和碳汇能力的主要因子除了植物种类组成以外,气温、海水温度、海水盐度、土壤理化性质、大气CO₂浓度及人类干扰等均有着重要作用.红树林湿地碳储量、碳汇能力的研究方法以实测法为基础,包括异速方程、遥感反演和模型模拟等.研究红树林湿地碳储量及碳汇能力,有利于深入认识红树林湿地碳循环过程及其调控机制,对红树林湿地的保护和合理利用具有重要意义.     

湿地生态系统碳储量估算方法综述

湿地生态系统碳储量测算一直是湿地研究领域的难点。目前仅能粗略估算湿地生态系统碳储量,很难做到精确计算。本文对湿地生态系统各组成部分碳储量估算方法进行分析,指出湿地生态系统碳储量估算应当充分融合水域和陆域各碳储存库的估算方法。另外,对影响湿地生态系统碳储量估算精度的各种因素进行了总结,认为湿地面积、碳密度以及水体、土壤和沉积物的深度是影响区域尺度碳储量估算精度的主要因素。     

湛江高桥红树林湿地有机碳分布及埋藏特征

红树林是世界上单位生产力最高的生态系统之一,其能够持续地固定有机碳,对全球碳平衡和生物地球化学循环有着深远影响。以广东湛江国家级红树林自然保护区高桥核心区为研究区,旨在分析我国典型红树林湿地的固碳潜力,为红树林湿地碳计量提供依据。在垂直于海岸线的两条样线上选取6个不同潮位的样点进行沉积柱取样分析,通过重铬酸钾氧化-外加热法测定有机碳含量,基于放射性同位素~(210)Pb定年推演沉积率,并对湿地有机碳密度和埋藏率进行计算。结果表明:研究区红树林湿地有机碳含量2.14—36.94 g/kg,平均(12.79±9.91)g/kg。红树林湿地有机碳密度为(0.0100±0.0056)g/cm3,空间上差异显著显著,水平方向上两条样线均以中带样点的有机碳密度最大,近陆侧(内带)样点的有机碳密度高于近海侧(外带);垂直方向上,内带和外带样柱的有机碳密度均以表层最高,而且随深度增加而减小。研究区红树林湿地百年尺度上沉积率为6.5—11mm/a,且外带样点沉积速率显著快于内带样点。有机碳埋藏率空间差异大,外带样点为(34.58±7.67)g m-2a-1,而中带样点可达150.56 g m-2a-1。红树林湿地有机碳的分布受潮位的影响大,更高潮位点和表层的有机碳含量和密度更高,而处于低潮位的外带样点的有机碳沉积更快。研究区红树林湿地有机碳含量和密度比更低纬度带低,但均高于地带性陆地植被,且其能够通过持续的沉积过程来捕捉和固定有机碳,固碳潜力大。     

中国滨海盐沼湿地碳收支与碳循环过程研究进展

滨海盐沼湿地由于其较高的初级生产力和较缓慢的有机质降解速率而成为缓解全球变暖的有效蓝色碳汇,近年来引起全球范围内的热切关注.我国滨海盐沼湿地分布较广,国内学者对滨海盐沼湿地碳循环及碳收支研究取得了一定进展,深入研究滨海盐沼湿地碳循环有助于对全球碳循环及全球变化的理解,并为利用滨海湿地进行碳的增汇减排提供科学依据.主要从我国滨海盐沼湿地碳循环主要观测方法、碳收支与碳循环过程及特点、碳库的组成与影响因素、气态碳的输入输出、潮汐作用对其碳收支的影响这5个方面出发,对国内的滨海盐沼湿地碳循环与碳收支的研究进展进行了归纳总结,并对今后的研究方向给出如下建议:(1)加强滨海盐沼湿地土壤碳库在深度上和广度上的研究;(2)标准化滨海盐沼湿地碳储量、碳通量的量化方法和观测技术;(3)在研究尺度上要宏观、微观并重,同时加强长期原位监测湿地碳通量的变化与室内模拟研究;(4)量化在潮汐影响下滨海盐沼湿地碳与邻近生态系统之间的横向交换通量.只有对我国滨海盐沼湿地碳库收支进行更准确的评估和长期的碳库动态变化监测,方可进一步认识我国盐沼湿地对全球气候变化的影响及其反馈作用,这对于预测全球变化及制定湿地碳储备功能的提升策略具有重要的意义.     

艾比湖湿地土壤有机碳及储量空间分布特征

土壤碳储量的研究是全球碳循环研究的热点,土壤碳库的变化对全球气候变暖、维护生态平衡都有着重要的意义。新疆的艾比湖湿地是干旱区典型的盐湖湿地,为探明该湿地有机碳特性及储量,选择艾比湖湿地1m深度的土壤作为研究对象,测试有机碳含量后,对艾比湖湿地土壤有机碳特性进行分析并分层定量测算有机碳储量,结果显示:(1)艾比湖湿地土壤有机碳整体偏低,随土层加深,含量依次递减的规律比较显著。湿地7种不同植被覆盖类型的土壤有机碳含量垂直空间变异性差异明显,其中荒漠河岸林、盐化草甸、小乔木荒漠大多属于强变异,而其它植被覆盖的土壤类型多属于中等变异。(2)艾比湖湿地7种不同植被类型土壤有机碳含量在相同土层的分布特征为:有机碳集中分布在浅表层(0—20 cm),从40 cm以下变幅缓慢,分布较为均匀。不同植被类型土壤有机碳在不同土层的分配比例差异比较明显,但表层(0—20 cm)大多占到30%以上。(3)艾比湖湿地土壤有机碳储量排序依次为小乔木荒漠盐化草甸干涸湖底灌木荒漠盐生灌丛荒漠河岸林寒湿性针叶林。湿地有机碳蓄积总量为7086862.83 kgC。上述研究结果可为新疆干旱区湿地生态系统恢复、保护与科学管理提供科技支撑。     

长江河口典型湿地碳库动态研究方法

湿地生态系统在维持碳平衡和全球气候调节中起着重要作用。长江河口湿地生态系统是国际公认的生态过程敏感区,选择长江河口典型湿地——崇明东滩作为长期碳循环观测和实验模拟的研究对象,针对长江河口湿地生态系统碳库动态研究具体的科学问题,从"土壤-植被-大气"连续体(SPAC)碳流过程监测、涡度相关法碳通量监测、植物生长控制实验(开顶式气候室,OTC)、"湿地碳循环-气候变化"生态过程模型构建、多方数据源校正等方面,总结了全球气候变化条件下长江河口湿地碳库动态的研究方法。旨在了解长江河口湿地生态系统碳库动态特征,探寻湿地碳平衡的主导控制因子,评估中国东部沿海湿地碳库对全球气候变化的响应。进而为提出长江河口湿地碳储备功能的保育策略提供理论依据。     

滨海盐沼湿地蓝色碳汇功能、形成机制及其增汇潜力

盐沼湿地具有很高的碳捕获与存储能力, 是缓解全球变暖的有效蓝色碳汇(蓝碳)。未来气候变暖和海平面上升可能增加盐沼湿地的固碳能力, 其蓝碳功能越来越受到国际社会的重视。该文重点围绕盐沼湿地蓝碳形成的关键过程、光合碳分配过程及影响机制、碳沉积埋藏特征及其来源解析、盐沼湿地土壤碳库稳定性及其微生物机制、盐沼湿地蓝碳过程动态模拟及其增汇潜力等5个方面进行综述。在此基础上, 针对当前研究的不足, 提出今后的研究中需要进一步探究盐沼湿地植被海陆梯度分布格局对碳吸收能力和碳分配的影响, 土壤有机碳沉积和埋藏速率及其对全球变化的响应, 盐沼湿地土壤碳库的稳定性及其横向碳流动, 气候变化和海平面上升背景下盐沼湿地蓝碳模拟与增汇潜力评估, 以及盐沼湿地蓝碳的增汇技术和途径。以期为深入理解盐沼湿地蓝碳形成过程与机制, 预测全球变化背景下盐沼湿地蓝碳功能的潜在变化趋势和制定蓝碳增汇途径提供理论支持, 助力碳达峰、碳中和目标实现。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.     

Enterovirus 71 3C proteolytically processes the histone H3 N-terminal tail during infection

Highlights
1. The N-terminal tail of histone H3 is specifically cleaved during EV71 infection.
2. Viral protease 3C is identified as a protease responsible for proteolytically processing the N-terminal H3 tail.
3. Our finding reveals a new epigenetic regulatory mechanism for Enterovirus 71 in virus-host interactions.     

Detection of EBV and HHV6 in the Brain Tissue of Patients with Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a rare pediatric neurological disorder, and the exact etiology is not clear. Viral infection may be involved in the pathogenesis of RE, but conflicting results have reported. In this study, we evaluated the expression of both Epstein-Barr virus (EBV) and human herpes virus (HHV) 6 antigens in brain sections from 30 patients with RE and 16 control individuals by immunohistochemistry. In the RE group, EBV and HHV6 antigens were detected in 56.7% (17/30) and 50% (15/30) of individuals, respectively. In contrast, no detectable EBV and HHV6 antigen expression was found in brain tissues of the control group. The co-expression of EBV and HHV6 was detected in 20.0% (6/30) of individuals. In particular, a 4-year-old boy had a typical clinical course, including a medical history of viral encephalitis, intractable epilepsy, and hemispheric atrophy. The co-expression of EBV and HHV6 was detected in neurons and astrocytes in the brain tissue, accompanied by a high frequency of CD8⁺ T cells. Our results suggest that EBV and HHV6 infection and the activation of CD8⁺ T cells are involved in the pathogenesis of RE.     

Perinatal Vertical Transmission of Chikungunya Virus in Ruili,a Town on the Border between China and Myanmar

正Dear Editor,Chikungunya virus (CHIKV), an arbovirus in the family of Togaviridae, genus Alphavirus, is transmitted by the A.aegyptii or A. albopictus mosquito, and causes disease in humans characterized by fever, rash, and arthralgia (Silva and Dermody 2017; Suhrbier 2019). It was first reported in 1953 in Tanzania, and caused only a few outbreaks and sporadic cases in Africa and Asia in last century. However, in the epidemic in 2004, CHIKV acquired mutations that conferred enhanced transmission by the A. albopictus mosquito(Schuffenecker et al. 2006). Since then, it has successively caused outbreaks in Africa, the Indian Ocean, South East Asia, the South America, and Europe (Zeller et al. 2016).     

Development of a Novel Reverse Transcription Loop-Mediated Isothermal Amplification Method for Rapid Detection of SARS-CoV-2

In conclusion, the novel visual RT-LAMP assay is a simple, rapid, and sensitive approach for detection of SARS-CoV-2, and it is ready for application in primary care and community hospitals or health care centers, and even patients' own houses in response to the current SARS-CoV-2 epidemic because the assay does not require sophisticated equipment and skilled personnel. Furthermore, it is also ready to be used in fields for screening samples from wild animals and environments to facilitate the identification of potential intermediate hosts that mediate the cross-species transmission of SARS-CoV-2 from bats to humans.