铁炉渣施加对稻田甲烷产生、氧化与排放的影响

为了阐明铁炉渣施加对稻田甲烷产生、氧化与排放的影响,采用静态箱-气相色谱法对对照(CK)、2 Mg/hm2(FeⅠ)、4Mg/hm2(FeⅡ)和8 Mg/hm2(FeⅢ)铁炉渣施加后稻田甲烷产生、氧化与排放进行了测定与分析.研究结果表明:观测期内,CK、Fe Ⅰ、FeⅡ和FeⅢ样地甲烷产生量分别为0.06-8.87、0.12-8.28、0.15-7.84、0.17-7.82 mg·m-2·h-1,平均产生量分别为4.68、3.92、3.14、2.76 mg·m-2·h-1;甲烷氧化量分别是0.02-1.27、0.09-0.95、0.09-1.54、0.09-2.79 mg·m-2·h-1,平均氧化量为0.46、0.47、0.59、0.55 mg·m-2·h-1;甲烷排放分别是0.04-7.99、0.03-7.33、0.06-6.30、0.08-5.12 mg· m-2·h-1,平均值分别为3.11、2.29、1.76、1.59 mg·m-2·h-1.铁炉渣的施加降低了甲烷产生量和排放通量,提高了甲烷氧化量.     

广州地区晚稻田CH4和N2O的排放通量及其影响因素

用密闭箱法同时研究了广州地区晚稻田CH4和N2 O的排放通量。结果表明 ,连续淹水、常规连作和水旱轮作等 3种处理的CH4平均排放通量分别为 1 7 63、2 84和0 36mg·m- 2 ·h- 1 ,而N2 O的平均排放通量分别为 6 74、1 1 69和 55 0 7μgN2 O N·m- 2 ·h- 1 ,表明稻田连续淹水显著增加CH4的排放而降低N2 O的排放。水旱轮作降低CH4排放而提高N2 O的排放 ,说明稻田CH4和N2 O排放之间存在着消长关系。讨论了这 2种温室气体排放的影响因素 ,并初步分析了它们对温室效应的相对贡献。     

Greenhouse gas fluxes of typical northern subtropical forest soils: Impacts of land use change and reduced precipitation北大核心CSCD

Aims: It is important to study the effects of land use change and reduced precipitation on greenhouse gas fluxes (CO2, CH4 and N2O) of forest soils. Methods: The fluxes of CO2, CH4 and N2O and their responses to environmental factors of primary forest soil, secondary forest soil and artificial forest soil under a reduced precipitation regime were explored using the static chamber and gas chromatography methods during the period from January to December in 2014. Important findings: Results indicate that CH4 uptake of primary forest soil ((-44.43 ± 8.73) μg C·m-2·h-1) was significantly higher than that of the secondary forest soil ((-21.64 ± 4.86) μg C·m-2·h-1) and the artificial forest soil ((-10.52 ± 2.11) μg C·m-2·h-1). CH4 uptake of the secondary forest soil ((-21.64 ± 4.86) μg C·m-2·h-1) was significantly higher than that of the artificial forest ((-10.52 ± 2.11) μg C·m-2·h-1). CO2 emissions of the artificial forest soil ((106.53 ± 19.33) μg C·m-2·h-1) were significantly higher than that of the primary forest soil ((49.50 ± 8.16) μg C·m-2·h-1) and the secondary forest soil ((63.50 ± 5.35) μg C·m-2·h-1) (p < 0.01). N2O emissions of the secondary forest soil ((1.91 ± 1.22) ug N·m-2·h-1) were higher than that of the primary forest soil ((1.40 ± 0.28) μg N·m-2·h-1) and the artificial forest soil ((1.01 ± 0.86) μg N·m-2·h-1). Reduced precipitation (-50%) had a significant inhibitory effect on CH4 uptake of the artificial forest soil, while it enhanced CO2 emissions of the primary forest soil and the secondary forest soil. Reduced precipitation had a significant inhibitory effect on CO2 emissions of the artificial forest soil and N2O emissions of the secondary forest (p < 0.01). Reduced precipitation promotes N2O emissions of the primary forest soil and the artificial forest soil. CH4 uptake of the primary forest and the secondary forest soil increased significantly with the increase of soil temperature under natural and reduced precipitation. CO2 and N2O emission fluxes of the primary forest soil, secondary forest soil and artificial forest soil were positively correlated with soil temperature (p < 0.05). Soil moisture inhibited CH4 uptake of the secondary forest soil and the artificial forest soil (p < 0.05). CO2 emissions of the primary forest soil were significantly positively correlated with soil moisture (p < 0.05). N2O emissions of primary forest soil and secondary forest soil were significantly correlated with the nitrate nitrogen content (p < 0.05). It was implied that reduced precipitation and land use change would have significant effects on greenhouse gas emissions of subtropical forest soils.     

闽江河口潮汐湿地二氧化碳和甲烷排放化学计量比

为了阐明河口潮汐湿地碳源温室气体排放的化学计量比特征,对闽江河口潮汐湿地二氧化碳和甲烷排放进行了测定与分析。结果表明:芦苇湿地和短叶茳芏湿地二氧化碳与甲烷排放均呈现正相关;涨潮前、涨落潮过程和落潮后芦苇湿地和短叶茳芏湿地CO2∶CH4月平均值分别为55.4和185.0,96.3和305.5,68.7和648.6,3个过程芦苇湿地和短叶茳芏湿地CO2∶CH4差异均不显著(P>0.05),2种植物湿地CO2∶CH4对潮汐的响应并不一致,但均在涨潮前表现为最低;涨潮前、涨落潮过程和落潮后均表现为芦苇湿地CO2∶CH4低于短叶茳芏湿地(P<0.05);河口潮汐湿地CO2∶CH4为空间变异性>时间变异性,潮汐、植物和温度均对CO2∶CH4的变化具有一定的调节作用。     

新疆天山高寒草原不同放牧管理下的CO_2,CH_4和N_2O通量特征

以中国科学院新疆巴音布鲁克草原生态站为依托,于2010年5月—2011年10月利用静态箱-气相色谱法对短期禁牧(2005年围封)、长期禁牧(1984年围封)和自由放牧(冬季放牧)3种草地的CO2、CH4、N2O气体通量进行了野外连续试验研究。结果表明:新疆天山高寒草原对CO2,CH4和N2O通量表现出明显的季节排放特点。在植物的生长季(5—10月),新疆天山高寒短期禁牧、长期禁牧和自由放牧草原的CO2通量平均值分别为:(89.8±49.3)、(52.8±28.7)、(57.0±30.7)mg·m-2·h-1,CH4通量平均值分别为:(-66.3±21.3)、(-104.5±32.8)、(-103.0±39.0)μg·m-2·h-1,N2O通量平均值分别为:(21.2±11.8)、(13.6±6.9)、(13.2±6.2)μg·m-2·h-1;短期禁牧草原与长期禁牧和自由放牧草原CH4平均通量具有显著性差异(P0.05),但CO2和N2O差异不显著(P0.05)。在植物的非生长季(11月—翌年4月),新疆天山高寒短期禁牧、长期禁牧以及自由放牧草原的3种温室气体的通量较低且差异均不显著。     

太湖流域源头溪流氧化亚氮(N_2O)释放特征

采用密闭箱法研究太湖流域源头溪流N2O释放特征及其影响因素。结果显示:南苕溪N2O释放通量范围在-18.11—397.42μg.m-.2h-1,平均值为(30.37±10.87)μg.m-.2h-1。溪流N2O释放呈现明显的季节模式。冬季释放通量最低,仅为(9.69±7.10)μg.m-.2h-1,夏季释放通量较高,为(17.17±17.35)μg.m-.2h-1;而释放高峰发生于汛期,其N2O释放通量可达(125.97±90.77)μg.m-.2h-1。持续降雨带来的山洪爆发及大量径流输入是造成汛期N2O大量释放的主要原因。从上游源头区至下游农田与城区,N2O释放通量逐渐升高;流域污染梯度对N2O释放通量影响显著。统计分析表明:水体硝态氮负荷是控制流域N2O释放通量变化的主导因素,其他因素如磷含量、溶解氧、地势因素对通量也具有倾向性的显著影响。估算苕溪干流临安段N2O年释放通量可达到0.38 t/a。结果显示:河流人为污染负荷增加时可显著促进河流N2O的释放。     

若尔盖高原湿地甲烷排放的时空异质性

集中于北美落基山高山湿地甲烷排放的零星报道远不能解析全球高山湿地甲烷源强. 因此,世界范围内其他区域高山湿地甲烷排放的研究对于合理估计全球高山湿地甲烷源强,意义重大.采用静态箱-气相色谱法,基于3种典型湿地类型的甲烷排放数据,认为若尔盖高原湿地生长季甲烷的平均排放量为4.69 mg CH4 m-2 h-1.同时根据2a数据,初步分析了甲烷通量及其对环境因素和生物因素的响应特征,结果表明:(1)甲烷排放昼夜变化具有双峰模式 (主峰出现在15:00,次峰出现在06:00),可由土壤温度以及植物气孔开启来解释.(2)若尔盖湿地甲烷排放季节动态较为典型,即在7月份或8月份出现排放高峰,冬季甲烷排放较少.生长季,对3类群落类型,表面温度与甲烷排放显著相关 (r2=0.55,P<0.05,n=30),地表水位和植物群落高度与甲烷排放相关性更为显著 (r2=0.32,0.61,P<0.01,n=30).分析认为该季节节律是由温度以及植物生长状况直接影响的,而水位则是使该节律发生波动的原因(高原气候).(3)群落尺度下,物候学上相当重要的两个时期,甲烷排放通量均有较高的空间变异 (植物生长高峰变异系数为38%,积雪融化高峰为61%).通过逐步回归线性分析,发现植物生长高峰期,地表水位和群落高度是影响甲烷排放空间差异的主要因素 (r2= 0.43,0.59,P<0.01,n=30).(4)景观尺度下,生长季,景观尺度下甲烷排放有较大的空间变异,湖滨湿地甲烷平排放量最高为11.95 mg CH4 m-2h-1,其次为宽谷湿地,其排放量为2 12 mg CH4 m-2h-1,河岸湿地表现为甲烷吸收,其吸收量为0.007 mg CH4 m-2h-1.地表水位、植物地上生物量以及植物高度能够很好地解释甲烷排放的景观差异.     

黄河口潮间盐沼湿地生长季净生态系统CO2交换特征及其影响因素

潮间盐沼湿地生物地球化学过程独特,生态系统CO2交换存在着极大的复杂性和不确定性。利用2012年黄河口潮间盐沼湿地生态系统生长季(4—10月)连续的涡度相关观测数据,分析了潮间盐沼湿地的净生态系统CO2交换(NEE)、总初级生产力(GPP)和生态系统呼吸(Reco)的变化特征及其影响因素。结果表明:生长季,生态系统NEE具有明显的日变化和季节变化。日尺度上,表现为白天CO2净吸收,夜间CO2净释放,NEE日平均值为-0.38 g CO2m-2d-1;月尺度上,平均气温最高的7月生态系统释放CO2最多(15.16 g C/m2),6月生态系统吸收CO2最多(25.07 g C/m2)。潮间盐沼湿地生态系统的CO2交换受到光合有效辐射(PAR)、土壤温度(Ts)、土壤含水量(SWC)和潮汐淹水的共同影响。白天NEE主要受控于PAR,且生态系统表观初始光能利用率(α)和最大光合速率(NEEsat)分别在6月和5月达到最大值,分别为(0.0086±0.0019)μmol CO2μmol-1光子和(4.79±1.52)μmol CO2m-2s-1。夜间NEE随Ts呈指数增加趋势,生态系统呼吸的温度敏感性(Q10)为1.33,且SWC越高,Q10值越大。研究典型晴天(6月19日—6月25日)表明,潮汐淹水增强了生态系统白天对CO2的吸收,同时也增强了夜间CO2释放,研究时段内,潮汐淹水使生态系统净CO2吸收增加了0.76 g CO2m-2d-1。整个生长季,黄河口潮间盐沼湿地生态系统表现为CO2的汇,NEE为-22.28 g C/m2(其中,吸收118.34 g C/m2,释放96.28 g C/m2)。研究结果利于对潮间盐沼湿地源汇功能和影响机制的进一步认识与研究。     

海岸带盐沼生态系统卤代甲烷释放研究进展

卤代甲烷是破坏臭氧层的主要物质,也是重要的痕量温室气体和有机污染物.目前,其源汇格局和全球收支存在很大的不确定性.受海陆两相交互作用影响的海岸带盐沼是卤代甲烷重要的自然来源.本文综述了卤代甲烷自然源汇的研究现状、海岸带盐沼卤代甲烷的释放规律以及主要影响因素.鉴于当前研究中存在的问题,其后的研究需在以下几个方面进一步加强: 1)较长时间尺度、更大区域范围的盐沼卤代甲烷释放规律及源汇评估研究;2)利用目前已比较成熟的稳定同位素技术,更精确地定量不同盐生植物种类以及各种生物类型对盐沼卤代甲烷的贡献比率;3)关注潮水对其产生的直接或间接影响,进一步研究潮汐涨落过程、淹水时长等对盐沼卤代甲烷释放的影响;4)人类活动和气候变化对盐沼卤代甲烷释放的影响.     

鄱阳湖苔草湿地非淹水期CO2释放特征

2009年9月至2010年4月非淹水期,在鄱阳湖南矶湿地国家级自然保护区,选择以灰化苔草为建群种的洲滩湿地,设置土壤-植物系统(TC)、剪除植物地上部分(TJ)2个试验处理(分别代表生态系统和土壤呼吸),利用密闭箱-气相色谱法测定了非淹水期鄱阳湖苔草湿地CO,释放通量.结果表明:苔草湿地生态系统呼吸与土壤呼吸均具有明显的季节变化模式,释放速率变化范围分别为89.57～1243.99和75.30～960.94 mg CO2·m-2·h-1,土壤呼吸占生态系统呼吸的比例为64%(39%～84%);土壤温度是苔草湿地CO2通量的主要控制因子,可以解释呼吸速率80%以上的变异;生态系统呼吸与土壤呼吸的温度敏感性指数(Q10)分别为3.31和2.75,且冬季的Q10值明显高于春秋季节;土壤水分与CO2释放速率之间未达到显著相关;非淹水期,鄱阳湖苔草湿地是大气CO2的汇,其强度为1717.72 g C·m-2.     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.