变化海洋中的甲烷气候临爆点潜力及生成悖论

在世纪时间尺度上,甲烷的全球增温潜势大约是二氧化碳的30倍.甲烷排放被认为导致了地球史上多次全球气候变化事件的发生和大规模的物种灭绝现象.因此,研究甲烷生成过程对于理解全球气候变化至关重要.长期以来一直认为,海洋中可检测到的生源甲烷完全是由低氧和无氧环境中产甲烷古菌的厌氧代谢活动产生的.但是,有众多研究报道显示,全球海洋范围内的许多含氧表面水体和近表水体中的甲烷是过饱和的,由此造成向大气甲烷净排放.含氧海水生成甲烷的现象被称为\"海洋甲烷悖论\".尽管该悖论仍未完全得到解决,但是最近的研究已经提出了一些有关含氧海水中甲烷生成的科学假说.文章将对甲烷在全球气候中的重要性的理解进行总结,并分析含氧海水环境中甲烷生成的生物过程及其机理.此外,我们将初步探讨相关微生物代谢过程与气候及海洋环境的全球性变化之间的关系.国家重点研发计划项目(编号:2016YFA0601303);;国家海洋局项目(编号:GASI-03-01-02-05);;国家自然科学基金项目(批准号:41676122、91328209、91428308);;中国海洋石油总公司项目(编号:CNOOC-KJ125FZDXM00TJ001-2014和CNOOC-KJ125FZDXM00ZJ001-2014)资

Inspirations from the scientific discovery of the anammox bacteria: A classic example of how scientific principles can guide discovery and development

厌氧铵氧化(anaerobic ammonium oxidation;anammox)是20世纪末被发现的氮循环新途径,这一重大发现不仅改变了生物代谢与物质循环的经典理论,而且深刻影响了对生物能量来源的认识,无光深海这个巨大的空间又多了一个可以进行化能自养"固碳"的微生物新成员.如果说海底热泉自养生物的发现是对"万物生长靠太阳"这一古训的挑战,广布于各种缺氧环境的anammox细菌的发现则可以说是对这一古训的完胜.anammox细菌以NO2?为最终电子受体氧化NH4+,生成N2,与反硝化微生物相似,在环境中行使着无机氮去除这一生物地球化学作用.然而,与异养的反硝化细菌不同,anammox细菌为无机化能自养细菌,从铵的厌氧氧化中获得代谢能形成跨膜质子驱动力(proton motive force;pmf)并合成细胞储能分子—三磷酸腺苷(ATP),进而进行无机碳固定.虽然anammox细菌与随后发现的另一极其重要的海洋氮素转化微生物—氨氧化古菌(AOA)—皆为化能自养微生物,但是,AOA以氨(而非铵根离子)为电子供体并以O2为最终电子受体进行能量代谢.因此,AOA生态过程主要发生在含氧的海水和沉积物中,而anammox细菌在缺氧的海水和沉积物中分布广泛,并在一些典型海洋极端环境中(如深海热液和海底冷泉)也有存在.一些研究显示,海洋中30%~70%氮气的产生可能源于anammox过程.在含氮污水处理工程领域,anammox构成了一种崭新的低能耗、低成本、高效率和节能减排技术.然而,这一科学发现来之不易,早在20世纪60年代就有科学家根据海洋地球化学观测数据提出了anammox这一生物地球化学过程存在的可能性,在20世纪70年代,有科学家根据化学反应热动力学原理,预测anammox细菌的存在,但在随后的十几年时间,该类微生物却一直没有被发现.作为低氧和缺氧环境中广泛分布的一类重要的氮循环细菌,是什么因素阻碍了其发现?又是什么因素最终促成了它的发现?对这些问题的分析给科学研究带来怎样的启示?本文从海洋anammox细菌生理生态学基础和科学研究规律出发,对上述问题进行了分析阐释.科技部创新方法工作专项项目(编号:2011IM010700);; 国家自然科学基金项目(批准号:91328209、91428308);; 国家重大科学计划项目(编号:2013CB955700);; 国家海洋局全球变化与海气相互作用专项项目(编号:GASI-03-01-02-05);; 中国海洋石油总公司“渤海海洋碳汇时间序列观测”(编号:CNOOC-KJ 125 FZDXM 00TJ 001-2014)和“南海西部海洋碳汇时间序列观测”科技项目(编号:CNOOC-KJ 125 FZDXM 00 ZJ 001-2014)资

海洋微型生物碳泵储碳机制及气候效应

海洋中存在一个巨大的惰性溶解有机碳(rdOC)库,可与大气CO2碳量相媲美.两个碳库之间的交换势必影响气候变化.rdOC可在海洋中保存数千年,构成了海洋储碳的重要机制.探寻rdOC碳库形成机制是认识海洋如何储碳的关键.新近提出的“海洋微型生物碳泵(MICrObIAl CArbOn PuMP,MCP)“理论指出,海洋微型生物是rdOC碳库的主要贡献者.本文从MCP的主动机制和被动机制及其环境调控出发,论述了海洋rdOC的组成与生物来源,rdOC组分的微型生物代谢途径,病毒的裂解过程以及浮游动物活动对rdOC生产的贡献,不同类群微型生物有机碳代谢特征及其生物标记物与碳氢同位素表征,以及MCP的能量代谢特征与储碳效率,并结合MCP储碳的地史证据展望了MCP在增加海洋储碳能力方面的应用前景.国家自然科学基金(批准号:91028001); 国家重大科学计划(编号:2013CB955700); 国家自然科学基金(批准号:91028005;91028011;41172030;41076091); 国家海洋公益性行业科研专项(批准号:201105021)资

中国海及邻近区域碳库与通量综合分析

中国海总面积约470万平方公里,纵跨热带、亚热带、温带、北温带等多个气候带.其中,南海北依\"世界第三极\"青藏高原、南邻\"全球气候引擎\"西太平洋暖池,东海拥有全球最宽的陆架之一,跨陆架物质运输显著,黄海是冷暖流交汇区域,渤海则是受人类活动高度影响的内湾浅海.中国海内有长江、黄河、珠江等大河输入,外邻全球两大西边界流之一的黑潮.这些鲜明的特色赋予了中国海碳储库和通量研究的典型代表意义.文章从不同海区（渤海、黄海、东海、南海）、不同界面（陆-海、海-气、水柱-沉积物、边缘海-大洋等）,以及不同生态系统（红树林、盐沼湿地、海草床、海藻养殖、珊瑚礁、水柱生态系统等）多层面对海洋碳库与通量进行了较系统地综合分析,初步估算了各个碳库的储量与不同碳库间的通量.就海气通量而言,渤海向大气中释放CO2约0.22Tg Ca-1,黄海吸收CO2约1.15Tg Ca-1,东海吸收CO2约6.92～23.30Tg Ca-1,南海释放CO2约13.86～33.60Tg Ca-1.如果仅考虑海-气界面的CO2交换,中国海总体上是大气CO2的\"源\",净释放量约6.01～9.33Tg Ca-1.这主要是由于河流输入以及邻近大洋输入所致.河流输入渤黄海、东海、南海的溶解无机碳（DIC）分别为5.04、14.60和40.14Tg Ca-1,而邻近大洋输入DIC更是高达144.81Tg Ca-1,远超中国海向大气释放的碳量.渤海、黄海、东海、南海的沉积有机碳通量分别为2.00、3.60、7.40、7.49Tg Ca-1.东海和南海向邻近大洋输送有机碳通量分别为15.25～36.70和43.39Tg Ca-1.就生态系统而言,中国沿海红树林、盐沼湿地、海草床有机碳埋藏通量为0.36Tg Ca-1,海草床溶解有机碳（DOC）输出通量为0.59Tg Ca-1;中国近海海藻养殖移出碳通量0.68Tg Ca-1,沉积和DOC释放通量分别为0.14和0.82Tg Ca-1.总计,中国海有机碳年输出通量为81.72～103.17Tg Ca-1.中国海的有机碳输出以DOC形式为主,东海向邻近大洋输出的DOC通量约15.00～35.00Tg Ca-1,南海输出约31.39Tg Ca-1.综上,尽管从海-气通量看中国海是大气CO2的\"源\",但考虑了河流、大洋输入、沉积输出以及微型生物碳泵（DOC转化输出）作用后,中国海是重要的储碳区.需要指出的是,文章数据是基于中国海各海区碳循环研究报道,鉴于不同研究方法上的差异,所得数据难免有一定的误差范围,亟待将来统一方法标准下的更多深入研究和分析.国家重点研发计划项目(编号:2016YFA0601400);;国家自然科学基金项目(批准号:91751207、91428308、41722603、41606153、41422603);;中央高校基础研究项目(编号:20720170107);;中海油项目(编号:CNOOC-KJ125FZDXM00TJ001-2014、CNOOCKJ125FZDXM00ZJ001-2014)资

Molecular Detection of <i>Candidatus</i> Scalindua pacifica and Environmental Responses of Sediment Anammox Bacterial Community in the Bohai Sea, China

<div><p>The Bohai Sea is a large semi-enclosed shallow water basin, which receives extensive river discharges of various terrestrial and anthropogenic materials such as sediments, nutrients and contaminants. How these terrigenous inputs may influence the diversity, community structure, biogeographical distribution, abundance and ecophysiology of the sediment anaerobic ammonium oxidation (anammox) bacteria was unknown. To answer this question, an investigation employing both 16S rRNA and <i>hzo</i> gene biomarkers was carried out. <i>Ca</i>. Scalindua bacteria were predominant in the surface sediments of the Bohai Sea, while non-<i>Scalindua</i> anammox bacteria were also detected in the Yellow River estuary and inner part of Liaodong Bay that received strong riverine and anthropogenic impacts. A novel 16S rRNA gene sequence clade was identified, putatively representing an anammox bacterial new candidate species tentatively named “<i>Ca</i>. Scalindua pacifica”. Several groups of environmental factors, usually with distinct physicochemical or biogeochemical natures, including general marine and estuarine physicochemical properties, availability of anammox substrates (inorganic N compounds), alternative reductants and oxidants, environmental variations caused by river discharges and associated contaminants such as heavy metals, were identified to likely play important roles in influencing the ecology and biogeochemical functioning of the sediment anammox bacteria. In addition to inorganic N compounds that might play a key role in shaping the anammox microbiota, organic carbon, organic nitrogen, sulfate, sulfide and metals all showed the potentials to participate in the anammox process, releasing the strict dependence of the anammox bacteria upon the direct availability of inorganic N nutrients that might be limiting in certain areas of the Bohai Sea. The importance of inorganic N nutrients and certain other environmental factors to the sediment anammox microbiota suggests that these bacteria were active for the <i>in situ</i> N transforming process and maintained a versatile life style well adapted to the varying environmental conditions of the studied coastal ocean.</p> </div

Environment-Dependent Distribution of the Sediment nifH-Harboring Microbiota in the Northern South China Sea

China NSFC [91028011, 41076091]; National Key Basic Research Program of China [2013CB955700, 2007CB411702]; Fundamental Research Funds for the Central Universities of China [09CX05005A]; U.S. NSF [0541797, 0948202]The South China Sea (SCS), the largest marginal sea in the Western Pacific Ocean, is a huge oligotrophic water body with very limited influx of nitrogenous nutrients. This suggests that sediment microbial N-2 fixation plays an important role in the production of bioavailable nitrogen. To test the molecular underpinning of this hypothesis, the diversity, abundance, biogeographical distribution, and community structure of the sediment diazotrophic microbiota were investigated at 12 sampling sites, including estuarine, coastal, offshore, deep-sea, and methane hydrate reservoirs or their prospective areas by targeting nifH and some other functional biomarker genes. Diverse and novel nifH sequences were obtained, significantly extending the evolutionary complexity of extant nifH genes. Statistical analyses indicate that sediment in situ temperature is the most significant environmental factor influencing the abundance, community structure, and spatial distribution of the sediment nifH-harboring microbial assemblages in the northern SCS (nSCS). The significantly positive correlation of the sediment pore water NH4+ concentration with the nifH gene abundance suggests that the nSCS sediment nifH-harboring microbiota is active in N-2 fixation and NH4+ production. Several other environmental factors, including sediment pore water PO43- concentration, sediment organic carbon, nitrogen and phosphorus levels, etc., are also important in influencing the community structure, spatial distribution, or abundance of the nifH-harboring microbial assemblages. We also confirmed that the nifH genes encoded by archaeal diazotrophs in the ANME-2c subgroup occur exclusively in the deep-sea methane seep areas, providing for the possibility to develop ANME-2c nifH genes as a diagnostic tool for deep-sea methane hydrate reservoir discovery

Thaumarchaeotal Signature Gene Distribution in Sediments of the Northern South China Sea: an Indicator of the Metabolic Intersection of the Marine Carbon, Nitrogen, and Phosphorus Cycles?

China NSFC [91028011, 41076091, 91028001, 91028005]; National Key Basic Research Program of China [2013CB955700, 2007CB411702]; China SOA [201105021]; U.S. NSF [0541797, 0948202]; National "Thousand Talents Program" at the State Key Laboratory of Marine Geology of Tongji University, Shanghai, ChinaThaumarchaeota are abundant and active in marine waters, where they contribute to aerobic ammonia oxidation and light-independent carbon fixation. The ecological function of thaumarchaeota in marine sediments, however, has rarely been investigated, even though marine sediments constitute the majority of the Earth's surface. Thaumarchaeota in the upper layer of sediments may contribute significantly to the reservoir of nitrogen oxides in ocean waters and thus to productivity, including the assimilation of carbon. We tested this hypothesis in the northern South China Sea (nSCS), a section of a large oligotrophic marginal sea with limited influx of nutrients, including nitrogen, by investigating the diversity, abundance, community structure, and spatial distribution of thaumarchaeotal signatures in surface sediments. Quantitative real-time PCR using primers designed to detect 16S rRNA and amoA genes in sediment community DNA revealed a significantly higher abundance of pertinent thaumarchaeotal than betaproteobacterial genes. This finding correlates with high levels of hcd genes, a signature of thaumarchaeotal autotrophic carbon fixation. Thaumarchaeol, a signature lipid biomarker for thaumarchaeota, constituted the majority of archaeal lipids in marine sediments. Sediment temperature and organic P and silt contents were identified as key environmental factors shaping the community structure and distribution of the monitored thaumarchaeotal amoA genes. When the pore water PO43- concentration was controlled for via partial-correlation analysis, thaumarchaeotal amoA gene abundance significantly correlated with the sediment pore water NO2- concentration, suggesting that the amoA-bearing thaumarchaeota contribute to nitrite production. Statistical analyses also suggest that thaumarchaeotal metabolism could serve as a pivotal intersection of the carbon, nitrogen, and phosphorus cycles in marine sediments

The POM-DOM piezophilic microorganism continuum (PDPMC)—The role of piezophilic microorganisms in the global ocean carbon cycle

The deep ocean piezosphere accounts for a significant part of the global ocean, hosts active and diverse microbial communities which probably play a more important role than hitherto recognized in the global ocean carbon cycle. The conventional biological pump concept and the recently proposed microbial carbon pump mechanism provide a foundation for our understanding of the role of microorganisms in cycling of carbon in the ocean. However, there are significant gaps in our knowledge and a lack of mechanistic understanding of the processes of microbially-mediated production, transformation, degradation, and export of marine dissolved and particulate organic matter (DOM and POM) in the deep ocean and the ecological consequence. Here we propose the POM-DOM piezophilic microorganism continuum (PDPMC) conceptual model, to address these important biogeochemical processes in the deep ocean. We propose that piezophilic microorganisms (bacteria and archaea) play a pivotal role in deep ocean carbon cycle where microbial production of exoenzymes, enzymatic breakdown of DOM and transformation of POM fuels the rapid cycling of marine organic matter, and serve as the primary driver for carbon cycle in the deep ocean

Deep-sea methane seep sediments in the Okhotsk Sea sustain diverse and abundant anammox bacteria

China 973 [2013CB955700, 2007CB411702, 2009CB219506]; NSFC [91328209, 91028011, 41076091]; China SOA [GASI-03-01-02-05]; US NSF [0541797, 0948202]Marginal sea methane seep sediments sustain highly productive chemosynthetic ecosystems and are hotspots of intense biogeochemical cycling. Rich methane supply stimulates rapid microbial consumption of oxygen; these systems are thus usually hypoxic to anoxic. This and reported evidence for resident nitrogen fixation suggest the presence of an anaerobic ammonium-oxidizing (anammox) bacterial community in methane seep sediments. To test this hypothesis, we employed detection of genes encoding 16S rRNA gene and hydrazine dehydrogenase (hzo) to investigate the structure, abundance and distribution of the anammox bacterial community in the methane seep sediments of the Okhotsk Sea. Diverse complements of Candidatus Scalindua-related 16S rRNA and hzo gene sequences were obtained. Most of the deep-sea sites harbored abundant hzo genes with copy numbers as high as 10(7)g(-1) sediment. In general, anammox bacterial signatures were significantly more abundant in the deep-water sediments. Sediment porewater NO3-, NOx- (i.e. NO3+ + NO2-), NOx-/NH4+ and sediment silt content correlated with in situ distribution patterns of anammox bacterial marker genes, likely because they determine anammox substrate availability and sediment geochemistry, respectively. The abundance and distribution of anammox bacterial gene markers indicate a potentially significant contribution of anammox bacteria to the marine N cycle in the deep-sea methane seep sediments

1995～2011年CERN土壤环境元素含量数据集

土壤环境是地球环境的重要组成部分。目前土壤环境问题的关注重点在于土壤污染。我国土壤污染以无机污染为主。中国生态系统研究网络(Chinese Ecosystem Research Network,CERN)自1988年组建以来,在中国主要农田、森林、草原、荒漠、湿地生态系统中,按统一的规范,对与土壤环境状况有关的铁、锰、铜、锌、硼、钼、镉、铬、铅、镍、汞、砷、硒元素进行了长期定位监测。通过对CERN典型生态样地表层土壤环境元素监测数据进行加工处理,获得1995～2011年中国陆地生态系统土壤环境元素含量数据集。本数据集中13种土壤环境元素指标测定的相对误差平均为6.55%,重复测定的相对偏差为7.70%。同时附有完整的背景信息,保证了数据在空间和时间上的一致性。本数据集可以为全国和区域土壤环境质量评估、土壤污染风险评价以及环境土壤学研究等工作提供数据基础