Hydrological management strategies for the control of algal blooms in regulated lowland rivers     

Jian Li  Wei Yin  Haiyan Jia  Xiaokang Xin 《水文研究》2021,35(6):e14171

Reservoirs of lowland floodplain rivers with eutrophic backgrounds cause variations in the hydrological and hydraulic conditions of estuaries and low-dam reservoir areas, which can promote planktonic algae to proliferate and algal bloom outbreaks. Understanding the ecological effects of variations in hydrological and hydraulic processes in lowland rivers is important for algal bloom control. In this study, the middle and lower reaches of the Han River, China, a typical regulated lowland river with a eutrophic background, are selected. Based on the effect of hydrological and hydraulic variability on algal blooms, a hydrological management strategy for river algal bloom control is proposed. The results showed that (a) differences in river morphology and background nutrient levels cause significant differences in the critical threshold flow velocities for algal bloom outbreaks between natural river and low-dam reservoir sections; there is no uniform threshold flow velocity for algal bloom control. (b) There are significant differences in the river hydrological/hydraulic conditions between years with and without algal blooms. The average river flow, water level and velocity in years with algal blooms are significantly lower than those in years without algal blooms. (c) For different river sections where algal blooms occur and to meet the threshold flow velocities, the joint operation of cascade reservoirs and diversion projects is an effective method to prevent and control algal blooms in regulated lowland rivers. This study is expected to deepen our understanding of the ecological significance of special hydrological processes and guide algal bloom management in regulated lowland rivers.  相似文献   

Isolation of Protoplasts from Undaria pinnatifida by Alginate Lyase Digestion     

HU Xiaoke  JIANG Xiaolu*  GUAN Huashi Fishery College  Ocean University of China  Qingdao  P..R.China 《中国海洋大学学报(英文版)》2003,2(1)

1　Introduction　Protoplastsserveasabasicandversatiletoolforge neticengineeringandbiochemicalresearchforseveralreasons :theymayregeneratetheirwallsandprovideamodelsystemforstudyingwallbiogenesis ,theirlysisprovidesagentlemeansofpreparingsubcellularor ganelles ,andthemembraneexpositionallowsgeneticmanipulationsinvolvingfusionoruptakeofnucleicacidstobepossible .Theseadvantagesarelessachiev ablewhenusingintactcells (Liciaetal.,1999) .Incomparisonwithlandplantsandunicellularalgae ,on lylimitedrepo…  相似文献   

The efifect of wave breaking on surface wave imaging by Synthetic Aperture Radar     

孙建  管长龙  史剑 《中国海洋湖沼学报》2006,(1)

The effect of ocean wave breaking as a non-Bragg mechanism on backscattering cross-section and modulation transfer functions (MTF) of radar was investigated based on Bragg resonance theory and parametric method. The result showed that the additional effect of wave breaking on backscattering cross-section is not more than 20% except for the small incident angle of VV polarized electromagnetic (e.m.) wave but is significant for HH polarized e.m. wave. Breaking waves lead to increase in the modulus of tilt modulation MTF and the larger the wind speed, the faster the increase. For large incident angle, the modulus of tilt modulation MTF with wave breaking decreases quickly with incident angle for HH polarization and approach to that without wave breaking for VV polarization. The hydrodynamic MTF increases 30%-60% when considering wave breaking and the increase is larger for HH polarization than for VV polarization.  相似文献   

Response of sediment characteristics to trophic state change at submerged macrophyte zones in a large shallow Lake Wuliangsuhai,China     

Liu  Zhenying  Jin  Zhaohui  Li  Yawei  Gu  Jiujun  Li  Tielong  Kang  Haiyan 《中国地球化学学报》2006,25(1):10-11

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Magnetic susceptibility variations of the Edicaran cap carbonates in the Yangtze platform and their implications for paleoclimate     

吴怀春  张世红  蒋干清  李海燕 《中国海洋湖沼学报》2005,(3)

1 INTRODUCTION One of the most intriguing phenomena in the late Neoproterozoic (~750 to 543 Ma) is the globa occurrence of thin carbonates that directly overlie glacial deposits in almost every continent (Kennedy 1996; Hoffman et al., 1998; Hoffman and Schrag 2002; Brasier and Shields, 2000; James et al., 2001 Jiang et al., 2003; Nogueira et al., 2003). These “cap carbonates”, commonly several to tens of meters thick, have attracted enormous interests because o their unusually negati…  相似文献   

高、低煤阶煤层气藏地质特征及控气作用差异性研究   总被引：4，自引：0，他引：4  

王勃  巢海燕  郑贵强  李景明  郭志斌  王红岩  刘洪林  李贵中 《地质学报》2008,82(10):1396-1401

高、低煤阶煤层气地质特征及控气作用差异性是研究煤层气富集成藏的重要组成部分,是煤层气勘探开发理论研究过程中重要的基础性研究领域之一。本文以中国沁水、阜新盆地和美国粉河盆地等典型的含气盆地为例,探讨了高、低煤阶煤层气的储层物性差异,分析了构造控气和水文地质控气作用的差异性。研究表明,高煤阶气藏含气量高,CH4百分含量高,δ13C1值大于-38.75‰,储层渗透率变化小,储层改造难,构造热事件对煤层气的生成、富集贡献大,持续的水动力使气藏遭到破坏,且破坏幅度大,现今地下水格局对气藏的形成具有一定的影响;低煤阶气藏含气量低,CH4百分含量低,δ13C1值大于-49.11‰,储层渗透率变化大,储层易改造,煤热演化史及煤阶影响着煤层气的生成、富集,在煤层气生成过程中活跃的水动力是甲烷生成的主要的水文地质条件之一,但持续的水动力使气藏遭到破坏,且破坏幅度小,而合适的地层水矿化度则是低煤阶煤层气生成的重要条件,地下水格局对气藏的调整和改造起到决定性的影响。  相似文献   

Occurrence and evolution of the Xiaotangshan hot spring in Beijing, China   总被引：1，自引：0，他引：1  

Zhou Haiyan  Zhou Xun  Chai Rui  Yu Lan  Liu Chunhui  Li Liangping 《Environmental Geology》2008,53(7):1483-1489

Thermal groundwater occurs in bedrock aquifers consisting of the dolomite of the Wumishan Group of the Jixianin System and the Cambrian carbonate in the Xiaotangshan geothermal field near the northern margin of the North China Plain, China. The hot water in the geothermal field of basin-type discharges partly in the form of the Xiaotangshan hot spring under natural conditions. The hot water has TDS of less than 600 mg/L and is of Na·Ca-HCO₃ type. The geothermal water receives recharge from precipitation in the mountain area with elevation of about 500 m above sea level to the north of the spring. Thermal groundwater flows slowly south and southeast through a deep circulation with a residence time of 224 years estimated with the Ra–Rn method. The Xiaotangshan hot spring dried up in the middle of the 1980s owing to the increasing withdrawal of the hot water in the geothermal field in the past decades. The water level of the geothermal system still falls continually at an annual average rate of about 2 m, although water temperature changes very little, indicating that the recharge of such a geothermal system of basin-type is limited. Over-exploitation has a dramatic impact on the geothermal system, and reduction in exploitation and reinjection are required for the sustainable usage of the hot water.  相似文献   

钙质成岩作用对有孔虫氧同位素的影响     

房殿勇  赵泉鸿  成鑫荣  关平  李洋冰 《海洋地质与第四纪地质》2005,25(2):63-66

通过对南海北部ODPl84航次1148站井深477m之下深海相渐新世浮游有孔虫Globoquadrina压扁壳、次生方解石和充填壳的氧同位素对比，定量分析了钙质成岩作用对壳体氧同位素的影响，结果发现，受成岩作用影响，1148站浮游有孔虫氧同位素显著变轻，这种变化趋势与低纬度开放性大洋明显不同。其原因可能与南海海盆扩张早期，大量陆源物质从较窄陆架可以直接沉积到海底，由于陆源物质氧同位素相对偏负，当与海洋沉积物混合后，引起本区沉积物孔隙水氧离子浓度变轻。而扩张初始，高的沉积速率可能使钙质壳体被快速封存在一个相对孤立的系统中，造成孔隙水离子成为影响壳体氧同位素变化的主要因素。当氧同位素相对较重的有孔虫壳体溶解和重结晶并与孔隙水离子发生交换时，引起壳体δ^18O负向偏移。  相似文献   

从厌氧反应器的发展谈UASB反应器的改良   总被引：10，自引：0，他引：10  

管锡珺  郑西来 《中国海洋大学学报(自然科学版)》2004,34(2):261-268

对厌氧反应器的发展沿革、技术现状和研究进展进行了较为全面的总结。介绍了第 1代、第 2代和第 3代厌氧反应器的特点及应用状况。分析了厌氧反应器的发展趋势 ,对比了 EGSB、IC反应器与 UASB反应器的结构特征 ,提出并验证了改良 UASB反应器。结果显示 ,改良 UASB反应器有利于提高负荷和设备开发。  相似文献   

长牡蛎碱性磷酸酶的分离纯化及部分性质研究   总被引：5，自引：1，他引：5  

李兴暖  韩雅莉  肖湘  邓瑞鹏  周小朋  管云雁  黄长江 《台湾海峡》2003,22(4):482-486

本文以长牡蛎为酶源提取材料,用正丁醇抽提,硫酸铵分级分离,DEAE-52和Sephadex G-100柱层析,得到一定纯度的碱性磷酸酶,提纯倍数为61.96,比活力达1.326U/mg.该酶的最适pH值9.6,最适温度38℃,初速度6.8μmol/(dm~3·min),米氏常数Km值为1.30mmol/dm~3.实验结果表明,Mg~(2+)对该酶有明显的激活作用;Zn~(2+)、Cu~(2+)、Hg~(2+)对该酶有明显的抑制作用.  相似文献