River flow control on the phytoplankton dynamics of Chesapeake Bay     

YU Qingyun  WANG You  TANG Xuexi  LI Ming 《中国海洋大学学报(英文版)》2013,12(1):103-114

Recent observations support an emerging paradigm that climate variability dominates nutrient enrichment in costal eco-systems, which can explain seasonal and inter-annual variability of phytoplankton community composition, biomass (Chl-a), and primary production (PP). In this paper, we combined observation and modeling to investigate the regulation of phytoplankton dynamics in Chesapeake Bay. The year we chose is 1996 that has high river runoff and is usually called a ’wet year’. A 3-D physical-biogeochemical model based on ROMS was developed to simulate the seasonal cycle and the regional distributions of phytoplankton biomass and primary production in Chesapeake Bay. Based on the model results, NO3 presents a strong contrast to the river nitrate load during spring and the highest concentration in the bay reaches around 80 mmol Nm-3 . Compared with the normal year, phytoplankton bloom in spring of 1996 appears in lower latitudes with a higher concentration. Quantitative comparison between the modeled and observed seasonal averaged dissolved inorganic nitrogen concentrations shows that the model produces reliable results. The correlation coefficient r2 for all quantities exceeds 0.95, and the skill parameter for the four seasons is all above 0.95.  相似文献   

一株底栖硅藻——双眉藻的优化培养     

周一春  胡超群  彭鹏飞  罗鹏  张吕平 《海洋科学》2012,36(10):40-47

双眉藻(Amphora sp.)是糙刺参(Stichopus horrens)喜食的优良饵料。本文采用光密度法分别测定了该藻在光照强度28～149 μmol/(m²·s)、温度20～35℃、盐度25~45 和氮质量浓度0～7 500 mg/L、磷质量浓度0～440 mg/L、硅质量浓度0～1 500 mg/L 以及氮磷硅多因子组合情况下的比生长速率, 探讨了光照、温度、盐度和不同质量浓度的氮、磷、硅单因子及多因子组合对该藻生长的影响, 以及该藻的最适生长条件。单因子试验结果表明, 该藻在光照范围为35～149 μmol/(m²·s)时都能良好生长, 最适光照为56～99 μmol/(m²·s), 低温时该藻生长缓慢, 最适生长温度为25～30℃。Amphora sp.为广盐性, 在盐度25～45 都能较好生长, 最适盐度为30～35。氮、磷、硅的最适质量浓度分别是750～7 500 mg/L、44 mg/L和150mg/L, 磷对该藻生长的影响比氮更显著。正交实验结果表明, 氮、磷、硅的最佳质量浓度分别为75 mg/L、44 mg/L 和150 mg/L, 最佳配比为2.4:1:3.4, 与其他底栖硅藻的相应指标存在一定的差异, 可能是物种和地域环境差异引起的, 反映出该藻适应高温、强光特殊栖息环境的特征。  相似文献   

Modeling the runoff and glacier mass balance in a small watershed on the Central Tibetan Plateau,China, from 1955 to 2008   总被引：1，自引：0，他引：1  

Hongkai Gao  Xiaobo He  Baisheng Ye  Jianchen Pu 《水文研究》2012,26(11):1593-1603

The glaciers on Tibetan Plateau play an important role in the catchment hydrology of this region. However, our knowledge with respect to water circulation in this remote area is scarce. In this study, the HBV light model, which adopts the degree‐day model for glacial melting, was employed to simulate the total runoff, the glacier runoff and glacier mass balance (GMB) of the Dongkemadi River Basin (DRB) at the headwater of the Yangtze River on the Tibetan Plateau, China. Firstly, the daily temperature and precipitation of the DRB from 1955 to 2008 were obtained by statistical methods, based on daily meteorological data observed in the DRB (2005–2008) and recorded by four national meteorological stations near the DRB (1955–2008). Secondly, we used 4‐year daily air temperature, precipitation, runoff depth and monthly evaporation, which were observed in the DRB, as input to obtain a set of proper parameters. Then, the annual runoff, the glacier runoff and GMB (1955–2008) were calculated using the HBV model driven by interpolated meteorological data. The calculated GMB fits well with the observed results. At last, using the temperature and precipitation predicted by climate models, we predicted the changes of runoff depth and GMB of the DRB in the next 40 years. Under all climate‐change scenarios, annual glacier runoff shows a significant increase due to intensified ice melting. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

The adaptation of Arctic phytoplankton to low light and salinity in Kongsfjorden （Spitsbergen）     

CUI Shikai  HE Jianfeng  HE Peimin  ZHANG Fang  LIN Ling  MA Yuxin 《极地研究(英文版)》2012,23(1):19-24

The basic environmental variables and adaptability ofphytoplankton communities to low light and salinity were stud- ied using incubation experiments in Kongsfjorden, a high Arctic fjord of Spitsbergen, in late summer 2006. Chlorophyll a concentrations were steady or decreased slightly in darkness after one day or one week incubation. Chlorophyll a concentrations showed an initial decline when exposed to natural light after one week incubation in darkness, and then increased significantly. In a salinity experiment, the maximal growth rate was observed at a dilution ratio of 10%, however, higher dilution ratios （≥0%） had an obvious negative effect on phytoplankton growth. We suggest that the phytoplankton communities in fjords in late summer are dark- ness adapted, and the inflow of glacial melt water is favorable for phytoplankton growth in the outer fiords where the influence of freshwater is limited.  相似文献   

Reexamination of the spawning migration of Anguilla dieffenbachii in relation to water temperature and the lunar cycle     

《新西兰海洋与淡水研究杂志》2012,46(1):131-147

ABSTRACT

The oceanic spawning migration of female Anguilla dieffenbachii eels was previously studied using pop-up satellite transmitting tags (PSAT). The swimming depths and experienced-temperature data of 3 eels released in May 2006 were re-examined in relation to water temperature data, and also lunar cycle and regional hydrography as these latter aspects were not considered in the original study. Eel 2 and Eel 3 initially experienced lower water temperature above 600?m, suggesting they remained south of the subtropical-convergence front longer than Eel 1. Their experienced nighttime minimum depths showed linear relationships with the lunar cycle, because they swam shallower during new moon than during full moon. The eels experienced narrow deep-day temperature ranges at a wide range of depths compared to experiencing narrow shallow-night depth ranges where temperatures varied more widely, indicating that several different factors determine their day and night depth ranges.  相似文献   

干旱遥感监测方法及其应用发展（可下载全文）   总被引：3，自引：0，他引：3  

刘欢  刘荣高  刘世阳 《地球信息科学学报》2012,14(2):232-239

 干旱是世界上影响范围最广和造成社会经济损失最严重的一种自然灾害。本文从干旱遥感监测的不同角度出发,总结了目前干旱遥感监测的主要方法、应用状况及优缺点。主要包括针对裸土地表类型的热惯量法、微波法,针对植被覆盖地表类型的可见光、近红外、短波红外等波段反射率数据的归一化植被指数法、距平指数法、条件植被指数法、归一化差值水分指数、归一化干旱指数、植被供水指数等,以及热红外遥感数据的温度植被干旱指数、温度条件指数、作物缺水指数、水分亏缺指数等。最后,提出了加强干旱遥感监测技术研究的建议,同时指出将可见光和微波相结合的指数模型的研究是干旱遥感监测可能的发展方向。  相似文献   

特征含水率对轻量土基本性质的影响规律     

侯天顺 《岩土力学》2012,33(9):2581-2587

为了研究最优含水率、流动上、下限含水率对轻量土性能的影响,通过密度、无侧限抗压强度试验研究了混合土的工程性质。结果表明：采用流动性指标 控制混合土的流动性基本可行。混合土处于流动性上、下限含水率时,无侧限应力-应变关系曲线几乎重合,流动性上、下限含水率范围内土壤性质较为接近。无侧限抗压强度随含水率增加而衰减,但流动上、下限含水率对应强度差别不大。不管含水率高低,强度随龄期增长,都可以采用双曲线模型进行预测,并且总结了7 d、90 d强度与28 d强度之间的经验关系。当含水率为最优含水率时,混合土基本不收缩;在流动性上、下限含水率范围内,线收缩率范围为1.53%～4.71%,体积收缩率范围为4.53%～13.46%,收缩性受含水率、水泥剂量等因素影响。理想密度模型可以近似预测混合土的湿密度,高含水率时预测值有一定误差,误差范围为3.834%～8.231%。  相似文献   

Weathering of granite in Antarctica: I. Light penetration into rock and implications for rock weathering and endolithic communities     

Kevin Hall  Mauro Guglielmin  Andrea Strini 《地球表面变化过程与地形》2008,33(2):295-307

Where rocks are composed of translucent minerals, light penetrates the rock and, in so doing, impacts on the thermal conditions. Where minerals are not translucent all the heat transformation must be at the rock surface, and steep thermal gradients can occur. Where light does penetrate, a component of the incoming radiation is transformed to heat at differing depths within the rock, thereby decreasing the thermal gradient. Equally, light transmissive minerals facilitate endolithic communities, which can also play a role in rock weathering. The attribute of light transmission within rock and the impact this has on the resulting thermal conditions has not been considered within rock weathering studies. An attempt was made to monitor the amount of light penetrating the outer 2 mm of coarse granite under Antarctic summer conditions and to evaluate the thermal impact of this. It was found that the amount of light penetration at this site exceeded modeled or postulated values from biological studies and that it could significantly impact the thermal conditions within the outer shell of the rock. Although the resulting data highlighted a number of flaws in the experimental procedure, sufficient information was generated to provide the first assessment of the range of thermal responses due to light transmissive minerals in rock. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

津滨轻轨地磁干扰范围的实验研究   总被引：1，自引：0，他引：1  

徐学恭  田山  韩润泉  张明东  胡培元  刘学历  马义山  刘金城 《地震地磁观测与研究》2008,29(6):41-44

在塘沽地震台与津滨轻轨之间及向北延长线建立野外磁测剖面,对轻轨运营期间的磁场干扰变化进行了实测研究,并对实测结果进行了曲线拟合,得出满足规划中的地磁观测网的环境要求——在以津滨轻轨铁路为骚扰源的影响范围,地磁观测网的地磁固定观测台距轻轨铁路的距离应大于24km。  相似文献   

Effect of chromophoric dissolved organic matter on epilimnetic stratification in lakes     

Sophie Caplanne  Isabelle Laurion 《Aquatic Sciences - Research Across Boundaries》2008,70(2):123-133

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