Identification of functionally active aerobic methanotrophs and their methane oxidation potential in sediments from the Shenhu Area,South China Sea     

Jing Li  Chang-ling Liu  Neng-you Wu  Xiao-qing Xu  Gao-wei Hu  Yan-long Li  Qing-guo Meng 《China Geology》2022,5(2):285-292

Large amounts of gas hydrate are distributed in the northern slope of the South China Sea, which is a potential threat of methane leakage. Aerobic methane oxidation by methanotrophs, significant methane biotransformation that occurs in sediment surface and water column, can effectively reduce atmospheric emission of hydrate-decomposed methane. To identify active aerobic methanotrophs and their methane oxidation potential in sediments from the Shenhu Area in the South China Sea, multi-day enrichment incubations were conducted in this study. The results show that the methane oxidation rates in the studied sediments were 2.03–2.36 μmol/gdw/d, which were higher than those obtained by sediment incubations from other areas in marine ecosystems. Thus the authors suspect that the methane oxidation potential of methanotrophs was relatively higher in sediments from the Shenhu Area. After the incubations family Methylococcaea (type I methanotrophs) mainly consisted of genus Methylobacter and Methylococcaea_Other were predominant with an increased proportion of 70.3%, whereas Methylocaldum decreased simultaneously in the incubated sediments. Collectively, this study may help to gain a better understanding of the methane biotransformation in the Shenhu Area.©2022 China Geology Editorial Office.  相似文献   

粉细砂地层防渗帷幕综合施工方法          下载免费PDF全文

丁跃军 《探矿工程》2015,42(4):76-78

四川省武都水库右岸EL574 m灌浆平洞揭露出厚度2.3～9.8 m的粉细砂层,普通水泥高压灌浆无法形成可靠的防渗帷幕。采用高压旋喷、湿磨细水泥、化学灌浆的组合处理方式,取得了较好的施工效果。通过钻孔压水、大功率声波CT、单孔声波、钻孔全景数字成像等方法检测,表明达到了设计防渗要求。  相似文献   

澳大利亚中部Alice Spring红色表土磁学特征分析     

温昌辉  刘秀铭  王涛  周子博  侯顺民 《第四纪研究》2015,35(4)

炎热干旱的澳大利亚中部是现代正在形成红色地表的区域.围绕中部Alice Spring地区采集了一系列红色地表样品.这些红色样品按照岩性大致可以分为三类:砂土、沙丘砂和岩石.通过对这些样品详细的磁学测量,发现这三类样品存在明显磁学特征差异,红色砂土和沙丘砂样品磁化率较岩石样品高出许多(砂土和沙丘砂磁化率均值为93.82× 10-8m3/kg),红色岩石样品磁化率值最低(均值为23.2×10-8m3/kg);三者主要磁性矿物也不尽相同;磁颗粒均以超顺磁(SP)颗粒为主,而单畴(SD)颗粒含量少.研究区百分比频率磁化率xfd％均值为8.28％,较黄土高原西部表土(兰州为3.5％)高出许多.该区现代年降水量约300mm,比兰州(约330mm)还低,成土导致百分比频率磁化率增高却比兰州明显高出几倍.这可能反映了黄土高原表土频率磁化率增高与降水量密切相关;而在澳洲中部可能与持续高温成土条件和作用的时间存在更密切的关系.澳洲中部不论岩石还是表土均以红色为主.磁学实验表明,砂土和沙丘砂样品均以磁铁矿为主,三类样品普遍含一定量磁赤铁矿和赤铁矿的贡献,与地表红色外貌相符.说明澳洲红色地表过程很可能是黑色磁铁矿颗粒表面被长期氧化条件下形成的红色磁赤铁矿/赤铁矿所包裹的现象,使得澳洲中部广大地区岩石露头和地表沉积物,普遍形成一层红色染色层.  相似文献   

2019/2020年冬季我国暖湿气候特征及成因分析     

赵俊虎  宋文玲  柯宗建 《气象》2020,46(7):982-993

2019/2020年冬季,我国大部分地区气温显著偏高,降水异常偏多,气候总体表现为“暖湿”的异常特征。异常成因分析表明：2019/2020年东亚冬季风强度较常年同期偏弱,西伯利亚高压异常偏弱,季节内冬季风强度阶段性变化特征显著;北极极涡收缩于极地,强度偏强,AO为异常偏强的正位相,乌拉尔山阻塞高压活动偏弱,东亚槽偏弱,欧亚中高纬以纬向环流为主;西太平洋副热带高压强度偏强、位置偏西偏北,印缅槽阶段性活跃,二者有利于太平洋和印度洋水汽向我国输送。受北半球环流异常的影响,我国冬季出现了“暖湿”的异常特征。进一步对东亚冬季风偏弱的可能原因分析表明：2019年秋冬季赤道中太平洋暖海温发展,2019年10月至2020年1月Ni〖AKn~D〗o3.4指数均大于0.5℃,这种类中部型El Ni〖AKn~D〗o海温异常有利于激发偏强、偏北的西北太平洋反气旋,进而抑制了东亚冬季风的发展和南下;此外,冬季北半球极涡收缩于极地,强度偏强,AO持续异常偏强的正位相,均不利于乌拉尔山阻塞高压的发展,且东亚大槽明显偏弱,共同导致了欧亚中高纬地区以纬向环流为主,东亚冬季风偏弱。  相似文献   

基于分段函数法计算湿球温度研究     

朱业玉  陈辉  姬兴杰 《气象与环境科学》2013,36(4):6-9

核电厂冷却塔设计气象条件中,湿球温度是重要的设计气象参数之一。近年来,由于实行自动观测,相对湿度值由仪器自动测定,因此不少气象站已经停止了湿球温度的观测,这给电厂气象参数的分析计算造成了一定困难。为此,根据气压分布型特点和分段函数,提出利用干球温度和相对湿度来计算湿球温度的新方法,经河南省郑州、南阳和商丘3站的应用,效果良好。  相似文献   

Changes in Daily Climate Extremes of Observed Temperature and Precipitation in China          下载免费PDF全文

WANG Ai-Hui  FU Jian-Jian 《大气和海洋科学快报》2013,6(5):312-319

Daily precipitation for 1960–2011 and maximum/minimum temperature extremes for 1960–2008 recorded at 549 stations in China are utilized to investigate climate extreme variations.A set of indices is derived and analyzed with a main focus on the trends and variabilities of daily extreme occurrences.Results show significant increases in daily extreme warm temperatures and decreases in daily extreme cold temperatures,defined as the number of days in which daily maximum temperature(Tmax)and daily minimum temperature(Tmin)are greater than the 90th percentile and less than the10th percentile,respectively.Generally,the trend magnitudes are larger in indices derived from Tmin than those from Tmax.Trends of percentile-based precipitation indices show distinct spatial patterns with increases in heavy precipitation events,defined as the top 95th percentile of daily precipitation,in western and northeastern China and in the low reaches of the Yangtze River basin region,and slight decreases in other areas.Light precipitation,defined as the tail of the5th percentile of daily precipitation,however,decreases in most areas.The annual maximum consecutive dry days(CDD)show an increasing trend in southern China and the middle-low reach of the Yellow River basin,while the annual maximum consecutive wet days(CWD)displays a downtrend over most regions except western China.These indices vary significantly with regions and seasons.Overall,occurrences of extreme events in China are more frequent,particularly the night time extreme temperature,and landmasses in China become warmer and wetter.  相似文献   

Interactions between sediment chemistry and frenulate pogonophores (Annelida) in the north-east Atlantic     

P.R. Dando  A.J. Southward  E.C. Southward  P. Lamont  R. Harvey 《Deep Sea Research Part I: Oceanographic Research Papers》2008,55(8):966-996

The small frenulate pogonophores (Annelida: Pogonophora a.k.a. Siboglinidae) typically inhabit muddy sediments on the continental slope, although a few species occur near hydrothermal vents and cold seeps. We present data on the distribution and habitat characteristics of several species on the European continental shelf and slope from 48°N to 75°N and show how the animals interact with the chemistry of the sediments. The environments inhabited include: shallow (30 m), organic-rich, fjord sediments; slope sediments (1000–2200 m) and methane seeps at 330 m depth. All the species studied obtain nutrition from endosymbiotic bacteria. They take up reduced sulphur species, or in one case, methane, through the posterior parts of their tubes buried in the anoxic sediment. We conclude that most species undertake sulphide ‘mining’, a mechanism previously demonstrated in the bivalves Lucinoma borealis and Thyasira sarsi. These pogonophores participate in the sulphur cycle and effectively lower the sulphide content of the sediments. Our results show that the abundance of frenulate pogonophores increases with increasing sedimentation and with decreasing abundance of other benthos, particularly bioturbating organisms. The maximum sustainable carrying capacity of non-seep sediments for frenulate pogonophores is limited by the rate of sulphate reduction.  相似文献   

湿浸硫酸镍工艺中的二次浸取     

李天才 《青海国土经略》1997,(1)

湿法浸取硫酸镍工艺研究中,净化提纯工艺采取了蒸发浓缩浸液、分步沉淀杂质的技术方案。中试表明,采用此种工艺生产效率很低,还导致生产流水线上的设备匹配性差。为此,作者提出了二次浸取的技术方案。实验室及中试试验表明:采用二次浸取工艺替代蒸发浓缩工艺,行之有效。  相似文献   

Volatile Organic Compounds in the Po Basin. Part B: Biogenic VOCs     

M.?Steinbacher  J.?Dommen  C.?Ordonez  S.?Reimann  F.?C.?Grüebler  J.?Staehelin  S.?Andreani-Aksoyoglu  A.?S.?H.?PrevotEmail author 《Journal of Atmospheric Chemistry》2005,51(3):293-315

Measurements of volatile organic compounds (VOCs) were performed in the Po Basin, northern Italy in early summer 1998, summer 2002, and autumn 2003. During the three campaigns, trace gases and meteorological parameters were measured at a semi-rural station, around 35 km north of the city center of Milan. Bimodal diurnal cycles of isoprene with highest concentrations in the morning and evening were found and could be explained by the interaction of emissions, chemical reactions, and vertical mixing. The diurnal cycle could be qualitatively reproduced by a three-dimensional Eulerian model. The nighttime decay of isoprene could be attributed mostly to reactions with NO₃, while the decay of the isoprene oxidation products could not be explained with the considered chemical reactions. Methanol reached very high mixing ratios, up to 150 ppb. High concentrations with considerable variability occurred during nights with high relative humidities and low wind speeds. The origin of these nighttime methanol concentrations is most likely local and biogenic but the specific source could not be identified.  相似文献   

GPS/MET水汽反演中T_m模型的本地化研究     

单九生  邹海波  刘熙明  吴琼 《气象与减灾研究》2012,35(1):42-46

利用江西省南昌和赣州两探空站12年(1999—2010年)每日2次(08时和20时)的探空资料,运用最小二乘法建立了江西地区的加权平均温度Tm模型(江西本地化Tm模型)。基于探空资料计算得到的Tm值,对比分析了江西本地化Tm模型、武汉本地化Tm模型和GAMIT默认Tm模型的模拟结果,发现江西本地化Tm模型的模拟效果最好,武汉本地化Tm模型相对较差。利用GAMIT软件,分别采用江西本地化Tm模型、武汉本地化Tm模型和GAMIT默认Tm模型,对2010年1月至2010年12月南昌、赣州等地的GPS大气可降水量进行了解算,并与探空计算的大气可降水量作了对比分析,结果发现采用江西本地化Tm模型后解算得到的GPS大气可降水量精度最高,而采用GAMIT默认Tm模型的精度相对较差。  相似文献