巢湖微囊藻毒素异构体组成的时空分布特征及影响因子     

余丽  朱广伟  孔繁翔  李胜男  史小丽  张民  阳振  许海  朱梦圆 《湖泊科学》2019,31(3):700-713

有害蓝藻释放微囊藻毒素（MCs）,严重威胁饮用水源地用水安全.为了解巢湖MCs污染状况及其异构体组成对水质的影响,于2012年夏季（8月）和秋季（11月）,2013年冬季（2月）和春季（5月）进行采样分析,研究了巢湖水体中胞内微囊藻毒素（IMCs）和胞外微囊藻毒素（EMCs）异构体的时空分布及其与环境因子的关系.结果发现,IMCs和EMCs的平均浓度变化范围分别为0.12~6.45 μg/L和0.69~1.92 μg/L.在3种常见的异构体中,MC-RR和MC-LR比例较高,MC-YR最低,MC-RR和MC-LR是巢湖水体中MCs的主要异构体类型.IMCs和EMCs的异构体浓度及其比例呈现不同的时空分布特征.微囊藻生物量、水温、总磷浓度是影响IMCs和EMCs异构体浓度及其组成变化的关键环境因子.本研究表明巢湖富营养化严重的西湖区夏季能合成更多的MC-RR异构体,而秋、冬季节偏向于释放生理毒性更强的MC-LR异构体.了解MCs异构体组成变化及其关键影响因素,有助于预测预警水体MCs污染状况和评估饮用水源地MCs风险.  相似文献   

滇西北贡山地块始新世花岗岩的成因及其构造意义     

康欢  卿兴全  陈岳龙  李大鹏  鲁震  胡国强  邓伟兵 《现代地质》2017,31(6):1177

滇西三江地区发育古近纪花岗岩,记录了印度－欧亚大陆碰撞的岩浆活动信息。对贡山地块福贡花岗岩开展岩石地球化学及锆石U Pb Hf系统研究,结果表明,该花岗岩为钙碱性、过铝质特征的I S型花岗岩。锆石U Pb同位素分析表明,福贡马吉花岗岩侵位于55 Ma,并含有252~77 Ma的继承锆石。锆石Hf同位素分析表明,该区岩浆锆石具有与青藏高原及东其南缘同时代长英质侵入体相似的Hf同位素组成,暗示其相似的岩浆起源。微量元素和同位素组成模拟计算结果表明,马吉花岗岩的原生岩浆是由53%的新生地壳组分和47%古老地壳基底物质混合而成的原岩经 5%~15%(F=005~015)的部分熔融而成。贡山地块福贡马吉花岗岩与冈底斯地块和腾冲地块早始新世岩浆岩(约55 Ma)具相似的年龄及地球化学特征,暗示它们之间可能存在类似的成因机制,均为新特提斯洋俯冲板片断离引起的壳内减压熔融的产物。  相似文献   

针对8051芯片RSA算法的选择明文SPA攻击     

曹娜娜  万武南  陈运  吴震 《成都信息工程学院学报》2011,26(4):357-361

针对随机数据作明文时,8051芯片RSA算法功耗曲线轮间差异不明显,提出采用特殊数据(如N-1,R-1等)作为明文,可获得功耗差异比较明显的曲线。验证真实环境下采用特殊数据作明文对8051芯片RSA算法进行SPA攻击,可以降低8051芯片密钥的破解难度,提高其功耗曲线攻击效率。最后,根据实验结果提出了提高智能卡安全的防御方法。  相似文献   

我国海藻产品自主品牌力的实证分析          下载免费PDF全文

秦臻  黄秀芳  王煜正 《海洋开发与管理》2021,38(6):19-23

海藻产品是海洋经济的重要组成部分,研究我国海藻产品的自主品牌力对我国海洋经济发展具有重要意义。文章构建基于消费者视角的自主品牌力评价模型,量化分析我国海藻产品（海苔）的整体品牌力; 在此基础上进行问卷收集,采用多元线性回归模型和Tobit模型进行分析。多元线性回归分析的维度显著性由高到低依次为品牌忠诚度、感知质量、社会可持续性和品牌联想,Tobit回归分析的维度显著性由高到低依次为品牌忠诚度、社会可持续性、感知质量和品牌联想,2种方法的回归结果均表明品牌忠诚度是最重要的因素。最后,从品牌忠诚度、社会可持续性、感知质量和品牌联想4个维度,提出提高我国海藻产品自主品牌力的建议。  相似文献   

南京玄武湖隆腺溞(Daphnia carinata)牧食对浮游植物的影响   总被引：1，自引：1，他引：0  

张镇  陈非洲  周万平  刘正文 《湖泊科学》2009,21(3):415-419

隆腺溞(Daphnia carinata)是许多湖泊的常见大型浮游动物,习居于富营养的水域中,以浮游植物为食,且滤食效率较高.通过浮游动物添加实验,研究了隆腺潘对南京玄武湖叶绿素和浮游植物群落结构的影响.结果表明,在隆腺涵组,浮游植物密度较对照组降低了83%,叶绿素较对照组下降了81%,氮、磷营养盐与叶绿素的相关性不显著.浮游植物的群落结构较对照组也发生了很大变化,蓝藻、绿藻和硅藻的比例有显著上升,隐藻呈显著下降趋势,金藻、甲藻和裸藻在实验结束时已没有检出.说明隆腺潘的摄食能有效控制浮游植物的生物量,可对浮游植物的群落结构产生显著影响.  相似文献   

过硫酸氢钾复合物对对虾养殖底泥硝化作用、氨氧化微生物丰度和群落结构的影响     

赵珍  王宝杰  刘梅  蒋克勇  王雷 《海洋科学》2021,45(11):54-61

采用在模拟池塘中投放过硫酸氢钾复合物（KMPS）进行对比实验的方法,探究KMPS对养殖底质硝化作用的影响。通过对氨氮和亚硝态氮含量的检测,探究对不同时期氮素转化的影响,低频率高剂量投放组中的氨氮和亚硝态氮含量显著降低,而高频率低剂量组中氨氮和亚硝态氮的含量显著上升。高频率低剂量KMPS的投放使氨氧化古菌（AOA）和氨氧化细菌（AOB）丰度降低,而低频率高剂量KMPS的投放不会造成丰度降低,而且还表现出部分时期AOB丰度的上升。进一步对群落结构进行分析发现KMPS的投放使AOA群落中Nitrosopumilu属相对丰度降低,Nitrososphaera属的相对丰度上升,这种相对丰度的变化与KMPS的投放方式无关;但AOB群落受到KMPS投放方式的影响,低频率高剂量的KMPS投放下AOB群落优势属相对丰度显著提高。以上结果均说明低频率高剂量KMPS的投放起到了促进底质硝化作用的效果。同时,可为KMPS用于对虾养殖池塘底质改良开辟一个新的途径。  相似文献   

Analysis and comparison of heat flux of landfast ice during 2016 in the Prydz Bay,Antarctica     

Guanghua Hao  Jie Su  Qinghua Yang  Long Lin  Shutao Cao 《海洋学报(英文版)》2021,40(5):71-79

Long term in situ atmospheric observation of the landfast ice nearby Zhongshan Station in the Prydz Bay was performed from April to November 2016. The in situ observation, including the conventional meteorological elements and turbulent flux, enabled this study to evaluate the sea ice surface energy budget process. Using in situ observations, three different reanalysis datasets from the European Centre for Medium-Range Weather Forecasts Interim Re-analysis(ERA-Interim), National Centers for Environmental Prediction Reanalysis2(NCEP R2), and Japanese 55-year Reanalysis(JRA55), and the Los Alamos sea ice model, CICE, output for surface fluxes were evaluated. The observed sensible heat flux(SH) and net longwave radiation showed seasonal variation with increasing temperature. Air temperature rose from the middle of October as the solar elevation angle increased.The ice surface lost more energy by outgoing longwave radiation as temperature increased, while the shortwave radiation showed obvious increases from the middle of October. The oceanic heat flux demonstrated seasonal variation and decreased with time, where the average values were 21 W/m~2 and 11 W/m~2, before and after August,respectively. The comparisons with in situ observations show that, SH and LE(latent heat flux) of JRA55 dataset had the smallest bias and mean absolute error(MAE), and those of NCEP R2 data show the largest differences.The ERA-Interim dataset had the highest spatial resolution, but performance was modest with bias and MAE between JRA55 and NCEP R2 compare with in situ observation. The CICE results(SH and LE) were consistent with the observed data but did not demonstrate the amplitude of inner seasonal variation. The comparison revealed better shortwave and longwave radiation stimulation based on the ERA-Interim forcing in CICE than the radiation of ERA-Interim. The average sea ice temperature decreased in June and July and increased after September,which was similar to the temperature measured by buoys, with a bias and MAE of 0.9°C and 1.0°C, respectively.  相似文献   

Spatial distribution and behavior of dissolved selenium speciation in the South China Sea and Malacca Straits during spring inter-monsoon period     

Wanwan Cao  Yan Chang  Shan Jiang  Jian Li  Zhenqiu Zhang  Jie Jin  Jianguo Qu  Guosen Zhang  Jing Zhang 《海洋学报(英文版)》2021,40(8):1-2

Selenium(Se) has been recognized as a key trace element that is associated with growth of primary producers in oceans. During March and May 2018, surface water(67 samples) was collected and measured by HG-ICP-MS to investigate the distribution and behavior of selenite [Se(IV)], selenate [Se(VI)] and dissolved organic selenides(DOSe) concentrations in the Zhujiang River Estuary(ZRE), South China Sea(SCS) and Malacca Straits(MS). It showed that Se(IV)(0.14–3.44 nmol/L) was the dominant chemical species in the ZRE, related to intensive manufacture in the watershed; while the major species shifted to DOSe(0.05–0.79 nmol/L) in the MS, associated with the wide coverage of peatland and intensive agriculture activities in the Malaysian Peninsula. The SCS was identified as the northern and southern sections(NSCS and SSCS) based on the variations of surface circulation.The insignificant variation of Se(IV) in the NSCS and SSCS was obtained in March, potentially resulting from the high chemical activity and related preferential assimilation by phytoplankton communities. Contrastively, the lower DOSe concentrations in the SSCS likely resulted from higher primary production and utilization during March. During May, the concentration of Se(IV) remained low in the NSCS and SSCS, while DOSe concentrations increased notably in the SSCS, likely due to the impact of terrestrial inputs from surface current reversal and subsequent accumulation. On a global scale, DOSe is the dominant Se species in tropical oceans, while Se(IV) and Se(VI) are major fractions in high-latitude oceans, resulting from changes in predominated phytoplankton and related biological assimilation.  相似文献   

稻虾轮作模式面源污染排放特征及其能值评估     

陶玲  彭亮  代梨梨  杨镇  陈思媛  可毅  李谷 《湖泊科学》2023,35(1):168-180

为探明稻虾轮作模式面源污染排放特征并合理评价该模式的环境可持续性,通过对江汉平原稻虾轮作模式小龙虾养殖排放尾水中总氮(TN)、总磷(TP)、COD和氨氮(NH₃-N)浓度进行监测,对稻虾轮作模式稻田养殖小龙虾的排污系数进行了估算,并采用等标污染负荷法进行了主要污染物解析。运用能值分析方法对稻虾轮作模式进行了包含面源污染的能值评估,对比单季稻模式,对其可持续发展能力进行了定量评价。结果表明：江汉平原稻虾轮作模式小龙虾养殖排放尾水中TN、TP、COD和NH₃-N的浓度范围分别为0.53～5.36、0.12～0.70、6.60～78.39和0.34～1.75 mg/L,TN、TP和COD平均排放浓度高于《地表水环境质量标准》(GB 3838-2002)Ⅲ类水质标准。等标污染负荷法分析结果表明TN的等标负荷比最高,是稻虾轮作模式面源污染控制的关键污染物。稻虾轮作模式小龙虾养殖排放尾水中TN、TP、COD和NH₃-N的排污系数分别为2.994、0.458、35.132和1.405 kg/t,表明稻虾轮作模式面源污染排放系数较低,对...  相似文献   

Simulation of geomembrane response to settlement in landfills by using the material point method     

Shijian Zhou  John Stormont  Zhen Chen 《国际地质力学数值与分析法杂志》1999,23(15):1977-1994

Because of the multiple layers of dissimilar materials and large deformations involved in the subsidence of a landfill system, large-scale computer simulation of the geomechanical response to subsidence with the use of conventional numerical methods are problematic. The Material Point (MPM), which was recently developed for dynamic problems such as penetration and perforation, is a newly emerging numerical method. The MPM is modified in this paper to simulate the geomechanical response of a landfill cover system that includes a geomembrane under quasi-static loading conditions. Sample problems, for which an analytical solution is available with certain assumptions, are considered to demonstrate the proposed solution procedure. Future work is discussed based on current research results. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献