Abundance and production of bacteria and their correlations with environmental factor

以2014年8月南海北部海水样品为研究对象,利用平板计数法和流式细胞仪计数法对南海北部表层和垂直海域可培养细菌和细菌总数分布状况进行研究,对细菌; 生产力进行测定,并结合环境因子进行相关性分析。结果表明:珠江口到南海北部海域,水平方向可培养细菌总数变化范围是3.70*10~2 ~; 1.42*10~3 CFU/mL,细菌总数变化范围是5.12 * 10~5 ~1.61 * 10~6; cells/mL,细菌生产力的变化范围是0.03 ~0.40 mg/m~3/h;垂直方向上可培养细菌变化范围是1.08 *10~3 ~9.00; *10~3 CFU/mL,细菌生产力变化范围是0.01 ~0.08; mg/m~3/h,其中表层海水中的细菌生产力明显高于底层。与环境因子相关性分析表明,水平方向上,影响南海北部表层海水细菌总数和细菌生产力的主要因; 素是温度、盐度、硝酸盐(NO_3-N)、硅酸盐(SiO_3-Si)、亚硝酸盐(NO_2-N)和磷酸盐(PO_4-P)(P<0.05);垂直方向上; ,影响南海北部可培养细菌总数的主要因素是NO_2-N(P<0.05),影响细菌生产力的主要影响因素是温度和盐度(P; <0.05)。可见,南海北部表层海水中细菌总数高于可培养细菌总数2; ~3个数量级,表明该海域表层海水存在大量不可培养细菌;细菌的生命活动在海水表层相较底层更为活跃。Distribution of abundance and production of bacteria and their; correlations with environmental factor were investigated, using plate; count method and flow cytometry, in the surface and vertical waters of; the northern south China sea in August 2014. The cultivable bacterial; abundance ranged from 3.70 * 10~2 CFU/mL to 1.42 * 10~3 CFU/ mL, the; total bacterial abundance ranged from 5.12 * 10~5 cells/mL to 1.61 *; 10~6 cells/mL and the bacterial productions varied from 0.03 mg/m~3/h to; 0.40 mg/m~3/h in horizontal distribution. In vertical distribution, the; cultivable bacterial abundance ranged from 1.08 * 10~3 CFU/mL to 9.00 *; 10~3 CFU/mL and the bacterial productions varied from 0.01 mg/m~3/h to; 0.08 mg/m~3/h, respectively. The correlation analysis results showed; that the environmental factors affecting the abundance of total bacteria; and bacterial productivity included temperature, salinity,; nitrate(NO_3-N),silicate (SiO_3-Si), nitrite (NO_2-N),and phosphate; (PO_4-P) (P<0.05). NO_2-N was the main influencing factor to cultivable; bacteria abundance (P < 0.05), while bacterial productivity was highly; correlated with temperature and salinity in vertical distribution of; northern south China sea (P < 0.05). The total bacterial abundance was 2; ~ 3 orders of magnitude higher than cultivable bacteria, suggesting that; there were many uncultured bacterium in surface water of northern south; China sea and bacterial activities in the surface maybe more active than; in the bottom.全球变化与海气交互作用; 国家重点研发计划全球变化及应对专项; 海洋公益性行业科研专

Diversity of CO_2 fixation gene in the surface waters of northern South China Sea in the Calvin cycle

为揭示南海北部表层海水中参与卡尔文循环的固碳基因多样性及其与环境因子的关系,本研究以卡尔文循环中的关键酶核酮糖-1,5-二磷酸羧化酶/加氧酶(Rubis CO)的Ⅰ、Ⅱ型基因(cbbL、cbbM)作为分子标记,采用Illumina Miseq高通量测序技术对海水中的固碳基因多样性进行分析,并结合多元统计分析的方法,探讨了固碳基因多样性与环境因子的关系.结果显示,在南海北部表层海水中,含cbbL基因固碳基因主要归属于变形菌门(Proteobacteria)、蓝藻门(Cyanobacteria)和厚壁菌门(Firmicutes),其中,优势亚群分别是γ-变形菌亚门(45.3%)、蓝细菌(30.9%)和β-变形杆菌亚门(23.8%);而含cbbM基因的固碳菌群未检测到;近岸的A9站位与其他站位物种组成有一定的差异,异着色菌属(Allochromatium)、硫杆菌属(Thiobacillus)和硫单胞菌属(Thiohalomonas)为其特有菌属.相关性和冗余分析(RDA)结果显示,含cbbL基因的固碳基因丰度与水温、盐度呈显著负相关(p<0.01),与硝酸盐、亚硝酸盐、硅酸盐呈显著正相关(p<0.01).To elucidate the diversity of CO_2 fixation and its relationship with environmental factors in surface water of northern South China Sea,the coding gene form I( cbbL) and form II( cbbM)( that encodes Ribulose-1,5-biphosphate carboxylase/oxygenase( Rubis CO) were chosen as biomarkers in Calvin-Benson-Bassham cycle( a common carbon fixation pathway for chemolithoautotrophic microorganisms) to analyze the carbon sequestration gene diversity. The Illumina Miseq sequencing method and multivariate statistical analysis were employed. The cbbM gene was not detected in any of samples,while the cbbL gene was found in all samples. The cbbL-containing genetic communities were dominated by Proteobacteria,Cyanobacteria and Firmicutes,in which γ-Proteobacteria( 45. 3%),Cyanobacteria( 30. 9%),β-Proteobacteria( 23. 8%) were predominant subpopulation. There were differences between the nearshore station of A9 with other stations,in which Allochromatiu,Thiobacillus and Thiohalomonas were unique species in A9 station.Relativity and redundancy analysis suggest that water temperature, salinity, nitrate, nitrite, silicate were highly statistically significant factors.Temperature and salinity were positively( p < 0. 01),while the other three factors negatively influenced CO_2 fixation gene of cbbL gene abundance( p <0. 01).全球变化与海气交互作用专项(No.GASI-03-01-02-05);; 海洋公益性行业科研专项(No.201305030,201405007)~

CVD纳米金刚石@碳化硅复合粉末导热填料制备工艺研究

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干旱区长期施肥对土壤活性碳组分及团聚体的影响/Effects of long-term fertilization on soil labile carbon fractions and aggregates in an arid area[J]

研究土壤活性有机碳组分和水稳定性团聚体的变化规律,对于评价长期不同施肥处理对绿洲农田土壤环境和区域碳循环具有重要意义.本文选取绿洲农田,设置长期撂荒(20 a)、无施肥、单施全量化肥和2种有机无机配施处理,测定不同处理土壤活性碳组分和水稳定性团聚体含量分布特征.结果表明,在表层(0～20 cm),开垦有利于颗粒碳、可溶性有机碳、可溶性无机碳和水稳定性大团聚体(＞0.25 mm)的累积;与不施肥相比,有机无机配施更有利于活性碳组分累积和水稳定性大团聚体形成和稳定.在相同处理中,表层颗粒碳和水稳定性大团聚体对整个剖面层次累积起主导作用,而表层可溶性有机碳和无机碳与之相反.活性碳组分与团聚体稳定性呈显著正相关

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies