Riverine input and air–sea CO₂ exchanges near the Changjiang (Yangtze River) Estuary: Status quo and implication on possible future changes in metabolic status     

Chen-Tung Arthur Chen  Weidong Zhai  Minhan Dai 《Continental Shelf Research》2008

Due to anthropogenic activities, the nutrient loadings of the Changjiang (Yangtze River) are strickly on the rise. The high nutrient concentrations notwithstanding, river water was pCO₂ supersaturated in the inner estuary during summer 2003 but decreased quickly in the mid-estuary due to mixing with low pCO₂ waters from offshore. In addition, settling of particles in the estuary resulted in better light conditions so that phytoplankton bloomed, driving down pCO₂ to ∼200 μatm. In the outer estuary and outside of the bloom area, pCO₂ increased again to near or just below saturation. Literature data also reveal that the mainstream of the Changjiang is always supersaturated with respect to CO₂ probably because the decomposition of terrestrial organic matter overwhelms the consumption of CO₂ due to biological production.  相似文献   

中国极端强降水日数与ENSO的关系   总被引：13，自引：0，他引：13       下载免费PDF全文

李威  翟盘茂 《气候变化研究进展》2009,5(6):336-342

利用G分布函数对中国1951-2004年地面台站逐日降水观测资料进行雨日降水量概率分布拟合并定义极端降水事件,在此基础上对极端降水日数与ENSO的关系进行分析研究。结果表明,ENSO对同期的极端降水发生频率在不同地区和不同季节表现出不同的影响作用。总体而言,中国极端降水事件更易发生在厄尔尼诺年的冬春季和拉尼娜年的夏秋季。极端降水在对ENSO强信号的滞后响应上,其发生频率在时空上发生了变化,主要表现为,多数地方更易在ENSO暖位相出现后的半年左右发生极端降水事件。研究表明,ENSO冷暖信号对我国极端降水事件多寡的影响具有不对称性。  相似文献   

Telescoping ore targets by geochemical exploration at multiple scales in Eastern Yunnan Pt geochemical province,southwestern China     

YongQing Chen  JingNing Huang  XiaoMing Zhai  BinBin Zhao 《中国科学D辑(英文版)》2009,52(5):627-637

Platinum has been one of the highly needed mineral resources in China. The geochemical exploration at two survey scales was applied in telescoping ore targets for the first time in Eastern Yunnan Pt geochemical province that was delineated using Pt data from flood plain sediments with extra-low sampling density. Our study was based on the delineations and assessments of both regional and local Pt anomalies using the Pt data by analyzing with C-OES the composite samples with two sampling densities. The composite samples were obtained by recomposing at two sampling densities the original stream sediment samples collected by the National Geochemical Mapping Project. Semi-variograms were used to quantitatively describe the variability of Pt anomalies and further analyze the factors controlling the variability. Pt resource potentials of both the regional Pt anomalies and the local Pt anomalies in the study area were estimated based on the geochemical block methods, respectively. It comes to the conclusions as follows. (1) From the regional to local Pt anomaly, the factors controlling their variability from the deep seated faults-basalts turn into the basalts-branch faults, which suggest that Semi-variograms could identify the geological factors controlling the variability of the Pt anomalies identified by the Pt data from the stream sediments with different sampling densities. (2) There exist two types of Pt anomalies in the study area. One is those displaying at sampling densities, and its average Pt concentration significantly increases with sampling density increasing. The other is getting weaker and/or disappears with sampling density increasing. This shows that TOTGEMS could gradually eliminate non-ore anomalies and keep ore anomalies. (3) The average Pt concentration of the local Pt anomaly blocks delineated using Pt data from stream sediments with sampling density of one composite per 16 km² is twice as much as that of the regional Pt anomaly blocks delineated using Pt data from stream sediments with sampling density of one composite per 64 km2. The Pt resource amount of the local Pt anomaly blocks is 60% of the regional anomaly blocks, but the area of the former is just 35% of the latter, which suggests that the Pt resource amount is mainly concentrated in its local anomalies, and that TOTGEMS has a good exploration function that efficiently approaches ore targets. Supported by National High-Tech Research & Development Program of China (863 Program) (Grant No. 2006AA06Z113) and National Natural Science Foundation of China (Grant No. 40772197)  相似文献   

Evolving patterns of the fluids within the TAG hydrothermal field     

HuaiMing Li  ShiKui Zhai  ZengHui Yu  ChunHui Tao  FengYou Chu 《中国科学D辑(英文版)》2009,52(1):29-37

The mixing of seawater/hydrothermal fluid within the large seafloor hydrothermal sulfide deposits plays a key role in the formation processes of the sulfide deposits. Some issues attract considerable attentions in the study of seafloor hydrothermal system in recent years, such as the relationships among different types of vent fluids, the characteristics of chemical compositions and mineral assemblages of the hydrothermal deposits and their governing factors. Combined with the measured data of hydrothermal fluid in the TAG field, the thermodynamic model of mixing processes of the heated seawater at different temperatures and the hydrothermal fluid is calculated to understand the precipitation mechanism of anhydrite and the genetic relationships between the black and white smoker fluids within the TAG mound. The results indicate that the heating of seawater and the mixing of hydrothermal fluid/seawater are largely responsible for anhydrite precipitation and the temperature of the heated seawater is not higher than 150°C and the temperature of the end-member hydrothermal fluid is not lower than 400°C. Based on the simulated results, the evolving patterns of fluids within the TAG deposit are discussed. The mixed fluid of the end-member hydrothermal fluid and the seawater heated by wall rock undergoes conductive cooling during upflowing within the deposit and forms “White Smoker” eventually. In addition, the end-member hydrothermal fluid without mixed with seawater, but undergoing conductive cooling, vents out of the deposit and forms “Black Smoker”. Supported by China Ocean Mineral Resources Research and Development Association Program (Grant No. DY115-02-1-01) and National Basic Research Program of China (Grant No. G2000078503)  相似文献   

人均历史累积排放权概念的操作性定义及分配方案研究          下载免费PDF全文

于胜民  高翔  翟丽华  马翠梅 《气候变化研究进展》2010,6(6):456-460

全球长期减排目标问题引发了各国对今后稀缺的大气温室气体容量资源如何进行公平分配的博弈,其中发展中国家提出了均等的人均历史累积排放权分配理念。该理念由于人口动态变化的因素存在4种可能的操作性定义,运用数学表达式推算出4种潜在的排放权分配方案。对4种方案的简单模拟和结果进行比较进一步揭示了各方案的优劣和特点。  相似文献   

Prediction of high-speed train induced ground vibration based on train-track-ground system model     

Wanming Zhai  Zhenxing He  Xiaolin Song 《地震工程与工程振动(英文版)》2010,9(4):545-554

The development of analysis on train-induced ground vibration is briefly summarized. A train-track-ground integrated dynamic model is introduced in the paper to predict the ground vibration induced by high-speed trains. Representative dynamic responses of the train-track-ground system predicted by the model are presented. Some major results measured from two field tests on the ground vibration induced by two high-speed trains are reported. Numerical prediction with the proposed train-track-ground model is validated by the high-speed train running experiments. Research results show that the wheel/rail dynamic interaction caused by track irregularities has a significant influence on the ground acceleration and little influence on the ground displacement. The main frequencies of the ground vibration induced by high-speed trains are usually below 80 Hz. Compared with the ballasted track, the ballastless track structure can produce much larger train-induced ground vibration at frequencies above 40 Hz. The vertical ground vibration is much larger than the lateral and longitudinal components.  相似文献   

天津北部4.00 Ma BP以来古植被与古气候          下载免费PDF全文

范淑贤  翟子梅  张学斌  吉云平  刘林敬 《古地理学报》2010,12(6):655-664

依据CQJ1孔275块孢粉样品分析结果,结合岩性特征和测年资料,建立了天津北部4.00 Ma BP以 来古植被与古气候变化序列。大约在3.60-4.00Ma BP, 天津北部植被以荒漠草原为主, 气候冷干;3.44- 3.60Ma BP植被为疏林草原, 气候温和湿润;3.18-3.44Ma BP植被为荒漠草原, 气候冷干;2.58-3.18Ma BP植被以针阔叶混交林草原为主,气候温暖湿润;1.90-2.58Ma BP植被以疏林草原为主,气候温凉偏干; 1.74-1.90Ma BP植被为荒漠草原,气候冷干;1.30-1.74Ma BP植被以针阔叶混交林为主,气候温暖潮湿; 0.78-1.30Ma BP植被为以针叶树种为主的针阔叶混交林草原,气候温和湿润;0.15-0.78Ma BP植被以针阔叶 混交林为主,气候温暖潮湿;0.15Ma BP以来,孢粉丰度呈现有规律的变化,3个高丰度层段分别相当于MIS（海洋氧同位素） １、３、５阶段,与河北平原东部具有可比性。  相似文献   

Molecular Cloning and Expression ofPoIR2, a Novel Gene Involved in Immune Response in Japanese Flounder （Paralichthys olivaceus）     

Shuo Li  Chunmei Li  Xubo Wang  Yanan Wang  Zhipeng Liu  Teng Zhai  Quanqi Zhang 《中国海洋大学学报(英文版)》2010,9(1):59-64

A novel immune-related gene was expressed in Japanese flounder (Paralichthys olivaceus) injected with Vibrio anguillarum. The complete cDNA contained a 169 bp 5’UTR, a 336 bp open reading frame (ORF) encoding 111 amino acids and a 556bp 3’UTR. Six exons and five introns were identified in the PoIR2 gene. Blastp similarity comparison showed its encoding protein had 50% similarity to Danio rerio neuromedin S (NMS), but further alignment indicated they did not have NMS C-terminal conservational signature domain. So it was not defined as an NMS homologue. Protein structure analysis indicated it had a 26aa signal peptide and was a secretory pathway protein. RT-PCR demonstrated that the expression of PoIR2 was quickly induced and drastically increased in liver, kidney, spleen, gills, intestine, heart, and skeletal muscle after infected with V. anguillarum. These results indicated that the PoIR2 might play some important role in Japanese flounder immune response system. This gene was named PoIR2 (P.olivaceus immune-related gene 2, GenBank accession number: EU224372). The mature PoIR2 peptide was expressed in BL21(DE3) pLysS using pET-32a(+) vector and a great part of the recombinant mature peptide existed as soluble type.  相似文献   

Vertical distribution of soil nematode communities under different tillage systems in lower reaches of Liaohe River     

Xuekun Hou  Ning Hu  Xiaoke Zhang  Lei Liang  Ruichang Zhai 《中国地理科学(英文版)》2010,20(2):106-111

Vertical distribution of soil nematode communities under conventional tillage (CT),no-tillage (NT) and fallow field (FF) treatments in the Lower Reaches of the Liaohe River was investigated at six soil depths (0-5 cm,5-15 cm,15-30 cm,30-50 cm,50-75 cm and 75-100 cm). The results show that total nematode abundance gradually decreases with depth,and the highest number of total nematodes is observed at 0-5 cm depth under NT and FF treatments. The number of fungivores and plant parasites is significantly higher...  相似文献   

Comparison of the <Emphasis Type="Italic">in vitro</Emphasis> and <Emphasis Type="Italic">in vivo</Emphasis> toxic effects of three sizes of zinc oxide (ZnO) particles using flounder gill (FG) cells and zebrafish embryos     

Li Han  Yanan Zhai  Yang Liu  Linhua Hao  Huarong Guo 《中国海洋大学学报(英文版)》2017,16(1):93-106

Nano-sized zinc oxide (nZnO) particles are one kind of the most commonly used metal oxide nanoparticles (NPs). This study compared the cytotoxic and embryotoxic effects of three increasing sized ZnO particles (? 30 nm, 80-150 nm and 2 μm) in the flounder gill (FG) cells and zebrafish embryos, and analyzed the contribution of size, agglomeration and released Zn²⁺ to the toxic effects. All the tested ZnO particles were found to be highly toxic to both FG cells and zebrafish embryos. They induced growth inhibition, LDH release, morphological changes and apoptosis in FG cells in a concentration-, size- and time-dependent manner. Moreover, the release of LDH from the exposed FG cells into the medium occurred before the observable morphological changes happened. The ultrasonication treatment and addition of serum favored the dispersion of ZnO particles and alleviated the agglomeration, thus significantly increased the corresponding cytotoxicity. The released Zn²⁺ ions from ZnO particles into the extracellular medium only partially contributed to the cytotoxicity. All the three sizes of ZnO particles tested induced developmental malformations, decrease of hatching rates and lethality in zebrafish embryos, but size- and concentration- dependent toxic effects were not so obvious as in FG cells possibly due to the easy aggregation of ZnO particles in freshwater. In conclusion, both FG cells and zebrafish embryos are sensitive bioassay systems for safety assessment of ZnO particles and the environmental release of ZnO particles should be closely monitored as far as the safety of aquatic organisms is concerned.  相似文献