Late Holocene marine productivity changes in Northern Patagonia-Chile inferred from a multi-proxy analysis of Jacaf channel sediments     

Lorena Rebolledo  Julio Sepúlveda  Carina B. Lange  Silvio Pantoja  Sébastien Bertrand  Konrad Hughen  Dante Figueroa 《Estuarine, Coastal and Shelf Science》2008

A multi-proxy approach based on organic (organic carbon, alkenones, and C/N) and inorganic geochemical proxies (biogenic opal, inorganic carbon, Fe, Ti, and Ca) preserved in the sediments of the Jacaf channel (CF7-PC33; 44°21′S, 72°58′W, 510 m water depth), Chilean fjords, yields evidence of major past productivity fluctuations in accordance with climatic changes over the last ∼1800 years. The downcore record clearly shows two productivity/climate modes. The first period, prior to 900 cal yr BP, is characterized by decreased marine productivity and a reduced continental signal, pointing to diminished precipitation and runoff. In contrast, the second period between ∼750 cal yr BP and the late 1800s (top of core) is illustrated by elevated productivity and an increased continental signal, suggesting higher precipitation and runoff. Both time intervals are separated by a relatively abrupt transition of ∼150 years which roughly coincides with the beginning of the Little Ice Age. The increased content of freshwater diatoms and Chrysophyte cysts that characterize the last 200 years of the latter mode coincides with a significant decrease in the carbonate content of the sediment; together they further indicate increased terrigenous contributions and decreased marine carbonate productivity at the end of the Little Ice Age. The correspondence between our record and other paleoclimate studies carried out in South America and Antarctica demonstrates that the Chilean fjord area of Northern Patagonia is not just sensitive to local climatic variability but also to regional and possibly global variability.  相似文献   

深海微生物多样性形成机制浅析   总被引：14，自引：0，他引：14  

席峰  郑天凌  焦念志  张瑶 《地球科学进展》2004,19(1):38-046

随着全球人口、资源与环境问题的加剧,人类把目光投向海洋。深海包含在极酸、极碱、极热、极冷、高盐、高压等极端环境下能够生存繁衍的微生物。与陆地微生物比较,它们可能具备某些不同的代谢途径和遗传背景。对极端环境微生物生存与适应机制的研究将加深我们对深海微生物乃至深海生物圈对全球气候影响的理解,也将促进我们对深海微生物资源和深海矿产资源的开发。在综合以往对各种极端环境下微生物研究的基础上对深海微生物的生存及适应机制进行了分析与阐释,为深海微生物的研究提供参考。  相似文献   

Evidence of methylmercury production and modification of the microbial community structure in estuary sediments contaminated with wastewater treatment plant effluents     

Ramond JB  Petit F  Quillet L  Ouddane B  Berthe T 《Marine pollution bulletin》2011,62(5):1073-1080

The Seine’s estuary (France) waters are the receptacle of effluents originating from wastewater treatment plants (WWTP). In this estuary, mudflats are deposition zones for sediments and their associated contaminants, and play an essential role in the mercury (Hg) biogeochemical cycle mainly due to indigenous microorganisms. Microcosms were used to assess the impact of WWTP-effluents on mercury methylation by monitoring Hg species (total dissolved Hg in porewater, methylmercury and total mercury) and on microbial communities in sediments. After effluent amendment, methylmercury (MeHg) concentrations increased in relation with the total Hg and organic matter content of the WWTP-effluents. A correlation was observed between MeHg and acid-volatile-sulfides concentrations. Quantification of sulfate-reducing microorganisms involved in Hg methylation showed no increase of their abundance but their activity was probably enhanced by the organic matter supplied with the effluents. WWTP-effluent spiking modified the bacterial community fingerprint, mainly influenced by Hg contamination and the organic matter amendment.  相似文献   

Studies on culture condition and extracellular hydrolase of psychrophilic bacteria from Arctic sea ice     

李晓晖  俞勇  李会荣  张琳  蒋欣音  任大明 《极地研究(英文版)》2008,19(1):77-84

Arctic sea ice in the polar region provides a cold habitat for microbial community. Arctic sea ice microorganisms are revealed to be of considerable importance in basic research and potential in biotechnological application. This paper investigated the culture condition and extraceIlular hydrolase of 14 strains of different Arctic sea ice bacteria. The results showed that optimal growth temperature of strains is 15 ℃ or 20 ℃. The optimal pH is about 8.0. They hardly grow at acid condition. 3 % NaCl is necessary for better growth. These strains have different abilities in producing amylase, protease, eellulase and lipase. Pseudoalteronomas sp. Bsi429 and Pseudoalteronomas sp. Bsi539 produced both cellulose, protease and lipase. These results provide a basis for further developing and exploiting the cold adapted marine enzyme resources.  相似文献   

Mineralization of a Proterozoic Sulfide Black Smoker Chimney and Thermophilous Microorganisms in Eastern Hebei, China   总被引：1，自引：1，他引：0  

XIA Xuehui  LIAN Wei  YUAN Congjian  YAN Fei  YUAN Jiazhong 《《地质学报》英文版》2008,82(4):858-863

A sulfide black smoker chimney exists in the Gaobanhe seabed exhalation massive sulfide deposit in the Xingiong-Kuancheng secondary fault basin of the Proterozoic Yaniiao rift trough in Hebei Province, taking the shape of mounds, individually about 2-3 cm high. Abundant fossils of thermophilous bacteria and algae in perfect preservation are found in the ore surrounding the black smoker chimney. Scanning electron microscopy （SEM） and molecular biomarker studies on the microorganismai ore fabric show that the microorganism in the sulfide ore is in fact a sedimentary product of probiotic bacteria and algae. In the special food chain based on black smoker chimney at ancient seabed- thermophilous bacteria, the thermophilous bacteria and algae reproduce in large quantity. Intermittently erupting of fluid from the chimney creats conditions for formation of sulfide deposit. In the process of exhalation action of hot fluid, thermophilous bacteria and algae grow and reproduce around the sulfide black smoker chimney, absorbing mineralizing substances brought by the fluid. Massive sulfide deposits are formed in this process of absorption of seabed black smoker chimney exhalation-mineralizing fluid pulsation-thermophilous microorganism.  相似文献   

Formation particularities of hypergene ferromanganese nodules: Far East Russia and Vietnam     

V. M. Novikov  E. L. Shkol’nik  E. A. Zhegallo  V. K. Orleanskii 《Russian Journal of Pacific Geology》2008,2(5):422-432

Ferromanganese nodules (pisolites) form accumulations in basal layers of Pliocene-Quaternary clayey sections of Far East Russia and Vietnam. They are composed of minerals that are in common for both these regions (authigenic vernadite, feroxyhyte, goethite, halloysite, and terrigenous quartz) and minerals that are characteristic of either the northern (authigenic hollandite, lithiophorite, and bernessite) or southern (authigenic alumophorite, lepidocrocite, ferrihydrite, gibbsite, and terrigenous ilmenite) regions. Pisolites are considered to be microbial colonies with Mn and Fe oxides frequently forming biomorphs. The growth of the colonies was accompanied by dying off and mineralization of microorganisms successively from the central toward the peripheral parts of the nodules. The formation of metalliferous pisolites was linked to the oxidizing geochemical barrier developed at the interface between compact sedimentary clays and the underlying porous readily permeable weathered products of basalts.  相似文献   

斑节对虾节水型养殖期间虾池硫化物含量的变化特征   总被引：4，自引：0，他引：4  

甘居利  林钦  李卓佳  黄洪辉  杨美兰  蔡文贵  王增焕  吕晓瑜  贾晓平 《台湾海峡》2005,24(1):83-89

在斑节对虾节水型养殖期间,观测了虾池底质和海水中硫化物含量的变化.结果表明,投放有益微生物的试验池与未投放有益微生物的对照池相比,底质硫化物含量波动较小,增高的速度较慢、增幅较小.在养殖后期试验池底质硫化物含量只增高了 68%,而对照池的增高了 252%.养殖过程中海水硫化物浓度呈阶段式和波浪式增高,在试验池中其浓度多数时间比对照池中的低.有益微生物能在一定程度上抑制水体和底质中硫化物的积累,但对老化虾池效果较差.由于节水型养殖模式利用有益微生物分解养殖过程中产生的有机物,采用单细胞藻类吸收利用营养盐,使养殖环境质量得到改善.  相似文献   

国外海洋抗肿瘤活性物质的研究与开发   总被引：15，自引：0，他引：15  

李盛英  郑忠辉 《海洋通报》2003,22(2):76-82

海洋生物是抗肿瘤活性物质的重要来源。近十几年来，已从不同的海洋生物中分离鉴定了许多结构新颖的抗肿瘤活性物质，显示出诱人的研究开发前景。本文综述了目前国外从海洋动物、海洋植物和海洋微生物抗肿瘤活性物质的研究开发进展。  相似文献   

Effect of Ecological Factors on the Distribution of Microorganisms in Regosols (Steppe of Priol’khonie, Siberia)     

Olga LOPATOVSKAYA  Anna SEREDKINA  Natalia BELKOVA 《《地质学报》英文版》2014,88(Z1):188-190

正1 Introduction Regosol in Eastern Siberia is intrazonal soil.In Priolkhonie region it occurs among chestnut soils,salt marshes and solonetzes.There are small information about Tagotskij hydrolaccolith in the research articles of geologists,archaeologists,and paleolimnologists when  相似文献   

高压下深海碳循环的过程及其对生命活动的影响     

刘亮霆  肖湘 《中国地质调查》2021,8(4):66-78

目前约25%化石燃料来源的CO₂被海洋吸收,缓解了人类活动对气候变化的影响。海洋通过多个概念的碳泵将大气中的CO₂输送到深海。深海高压和低温的特点有利于CO₂溶解,目前已经储存了相当于大气含量50倍的无机碳,另外,深海沉积物中还储存有大量甲烷水合物。认识深海中的碳循环过程,对于保护海洋固碳能力、开发固碳潜力有重要意义。总结了国内外在海洋碳库、碳输送研究方面的进展,重点讨论了深海C元素转化循环的过程以及高压对生命活动的影响。微生物驱动了深海碳循环,大部分浮游植物所包含的有机碳在沉降过程中被微生物矿化成CO₂以及转化为难降解的有机碳,使深海成为巨大的、长周转时间的有机碳库; 高压能提高古菌甲烷厌氧氧化的活性,提升屏蔽海底甲烷释放的能力,同时,高压下氧化甲烷的过程中不仅产生碳酸氢盐,还产生可支持异养生物的乙酸,因此,全球甲烷厌氧氧化的通量可能被低估; 高压下细胞代谢额外产生的氨,可作为氨氧化古菌固定无机碳的潜在能量来源。总之,研究现在以及未来的人类活动对深海碳循环过程的影响以及环境效应,评估应用深海作为地球工程技术平台封存CO₂的可能性,都迫切需要加深对碳循环在内的深海元素循环的认识。  相似文献