不同饵料种类、投喂方式及环境条件对凡纳滨对虾相对摄食量的影响     

肖善势  何琳  徐永健  何京  林志华 《海洋科学》2016,40(5):36-42

为提高对虾养殖过程中的饵料利用率并减少养殖废水的排放,作者以凡纳滨对虾(Litopenaeus vannamei)为实验对象,研究了不同饵料种类、投喂方式、体质量、充气量、光照强度、水温及盐度对其相对摄食量的影响。结果表明:配合饲料组对虾的相对摄食量显著高于冰鲜虾肉组;连续单颗投喂时对虾的相对摄食量较高;相对摄食量随对对虾体重升高而显著(P0.01)下降,而且不同规格的对虾在竞争条件下平均相对摄食量会降低;充气量6 L/min组对虾的相对摄食量明显高于另外两组;弱光环境下对虾的相对摄食量较高;水温和盐度对相对摄食量的影响极显著(P0.01),在32℃时对虾获得最大相对摄食量,在盐度为5时相对摄食量最小,高盐度下组间差异不显著(P0.05)。因此,在实际生产中应采取少量多次的投饵策略,并根据环境条件的变化合理的调整投饵量。  相似文献   

长江口及其邻近海域叶绿素a分布特征及其与低氧区形成的关系   总被引：2，自引：0，他引：2  

李照  宋书群  李才文 《海洋科学》2016,40(2):1-10

于2013年3月和8月研究了长江口及其邻近海域叶绿素a的分布特征,并对环境因子和长江冲淡水对浮游植物生物量分布的影响进行了探讨。结果表明,叶绿素a浓度在丰水期较高,平均值为5.18μg/L,最高值达32.05μg/L,现场海水出现变色现象;与同期历史资料对比分析,发现该海域叶绿素a浓度呈现出波动增长趋势。丰水期与枯水期叶绿素a的相对高值区均位于冲淡水的中部,122.5°E~123°E之间;丰水期在调查海域出现溶解氧低值区与低氧区,最低值仅为0.64 mg/L;发现低氧区出现位置北移、面积扩大和溶解氧最低值下降的趋势。底层溶解氧低值区分布与表层叶绿素高值区大致吻合,表明低氧现象与表层浮游植物的生长和现存量密切相关,在跃层存在的水体中表层浮游植物的大量繁殖易造成底层低氧区的出现。  相似文献   

反渗透海水淡化技术现状和展望     

高从堦  周勇  刘立芬 《海洋技术学报》2016,(1):1-14

反渗透膜技术于20世纪60年代取得突破性进展,促使反渗透海水淡化在近50年间高速发展,淡化产能自20世纪90年代起激增.海水反渗透(SWRO)淡化已成为目前投资最省、成本最低的利用海水制备饮用水的过程.文中主要对海水反渗透淡化的发展状况进行了介绍,如膜和组件的改进,关键设备高压泵和能量回收装置效率的提高,多种工艺过程的不断发展,包括预处理和后处理的新工艺,以及对环境的影响和相应对策等.反渗透技术的发展也推动了其他膜分离技术的进步,并扩展其应用领域.预计在不久的将来,膜技术在海水淡化和水再利用、扩大和保护水资源、循环经济、清洁生产、改造传统产业、节能减排及提高人民生活水平等方面发挥的作用会越来越显著.  相似文献   

Discussion on applying an analytical method to optimize the anti-freeze design parameters for underground water pipelines in seasonally frozen areas     

Ji Chen  JingYi Zhao  Kun Li  Yu Sheng 《寒旱区科学》2016,8(6):467-476

Adopting the quasi-three-dimensional (Quasi-3D) numerical method to optimize the anti-freeze design parameters of an underground pipeline usually involves heavy numerical calculations. Here, the fitting formulae between the safe conveyance distance (SCD) of a water pipeline and six influencing factors are established based on the lowest water temperature (LWT) along the pipeline axis direction. With reference to the current widely used anti-freeze design approaches for underground pipelines in seasonally frozen areas, this paper first analyzes the feasibility of applying the maximum frozen penetration (MFP) instead of the mean annual ground surface temperature (MAGST) and soil water content (SWC) to calculate the SCD. The results show that the SCD depends on the buried depth if the MFP is fixed and the variation of the MAGST and SWC combination does not significantly change the SCD. A comprehensive formula for the SCD is established based on the relationships between the SCD and several primary influencing factors and the interaction among them. This formula involves five easy-to-access parameters: the MFP, buried depth, pipeline diameter, flow velocity, and inlet water temperature. A comparison between the analytical method and the numerical results based on the Quasi-3D method indicates that the two methods are in good agreement overall. The analytic method can be used to optimize the anti-freeze design parameters of underground water pipelines in seasonally frozen areas under the condition of a 1.5 safety coefficient.  相似文献   

Cutting of Phragmites australis as a lake restoration technique: Productivity calculation and nutrient removal in Wuliangsuhai Lake, northern China     

Jan Felix K&#;bbing  Niels Thevs  Stefan Zerbe 《寒旱区科学》2016,8(5):400-410

Reed is one of the most frequent and dominant species in wetlands all over the world, with common reed (Phragmites australis (Cav.) Trin. ex Steud.) as the most widely distributed species. In many wetlands, P. australis plays a highly ambivalent role. On the one hand, in many wetlands it purifies wastewater, provides habitat for numerous species, and is a potentially valuable raw material, while on the other hand it is an invasive species which expands aggressively, prevents fishing, blocks ditches and waterways, and builds monospecies stands. This paper uses the eutrophic reed-swamp of Wuliangsuhai Lake in Inner Mongolia, northern China, as a case to present the multiple benefits of regular reed cutting. The reed area and aboveground biomass production are calculated based on field data. Combined with data about water and reed nutrient content, the impact of reed cutting on the lake nutrient budget (N and P) is investigated. Currently, at this lake around 100,000 tons of reed are harvested in winter annually, removing 16% and 8% of the total nitrogen and phosphorus influx, respectively. Harvesting all available winter reed could increase the nutrient removal rates to 48% and 24%, respectively. We also consider the effects of summer harvesting, in which reed biomass removal could overcompensate for the nutrient influx but could potentially reduce reed regrowth.  相似文献   

南极长城站验潮站数据处理和潮汐特点初步分析          下载免费PDF全文

张保军王泽民  安家春艾松涛 柯灝 《极地研究》2016,28(4):498-504

继在南极中山站建成我国南极首个永久性验潮站后,2012年1月在南极长城站又建成了我国南极第二个永久性验潮站。通过对长城站验潮站相关数据进行分析处理,得到了验潮基准系统的水准网平差结果和验潮仪零点标定结果,以及长城站附近海域海洋潮汐170个分潮的调和常数,并据此进行了潮汐预报,同时分析了长城站潮汐余水位的变化特征,探讨了利用附近的Antarctic Base Prat验潮站的余水位改正长城站潮汐预报的可行性,结果表明使用Antarctic Base Prat验潮站余水位改正长城站潮汐预报,可以显著提高长城站验潮站潮汐预报的精度,余水位改正后2014时段的潮汐预报中误差为±3.42 cm,明显好于改正前的预报中误差±10.43 cm。  相似文献   

赵各庄矿地下水位时间序列数字滤波分析          下载免费PDF全文

殷传印  朱斌  司雯雯 《山东国土资源》2016,32(2)

为了更好地了解煤矿地下水位的变化趋势,结合工程实例,运用递归和非递归2种滤波技术进行分析,通过对比2种滤波技术的滤波效果,可以得到地下水位的变化规律和成因机理。结果表明:滤波系数的调校对滤波效果的影响至关重要。根据平滑度指标、均方根误差和信噪比对现有观测数据进行计算的结果可知,当b=0.5时递归滤波效果相对较好,当q=5时非递归滤波效果相对较好。滤波结果可以作为预测未来该地区地下水位变化趋势的依据,也可以为安全生产提供参考。  相似文献   

沂蒙缺水山区地下水赋存规律及找水定井范例   总被引：1，自引：0，他引：1       下载免费PDF全文

贾德旺  赵庆令 《山东国土资源》2016,32(5)

沂蒙山区是山东省重点贫困缺水地区,缺水区域分布较广,区内地质条件复杂,找水难度极大。通过综合分析区内气象水文、岩性特征、地质构造及地形地貌等地质因素,初步查明了不同地段含水层的结构和富水性;并结合水文地质调查、物探、钻探等综合勘探方法和手段,实施了探采结合孔8口,成功率100%,满足了区内约3万余人的饮用及300余亩土地灌溉用水需求,取得了良好的经济和社会效益。为我国北方严重缺水山区找寻地下水起到了宝贵的指导和示范作用。  相似文献   

基于主成分分析的济宁市环境承载力研究          下载免费PDF全文

赵庆令  李清彩  田光彩  肖宁 《山东国土资源》2016,32(1)

该文以济宁市环境承载力为研究对象,运用主成分分析法,从影响环境污染状况、环境治理状况、人口状况、经济发展状况、自然资源状况、物耗能耗状况等19个指标中,提取出影响环境承载力动态变化的3个主成分,对济宁市环境承载力年际变化进行了综合评价。结果表明:2006—2010年,济宁市环境承载力呈现逐年上升的趋势。该研究评价结果较好,可以为该地区的可持续开发规划提供理论参考。  相似文献   

Hispanic Immigrants' Vulnerabilities to Flood and Hurricane Hazards in Two United States Metropolitan Areas          下载免费PDF全文

Alejandra Maldonado  Timothy W. Collins  Sara E. Grineski 《Geographical review》2016,106(1):109-135

Research reveals that disasters are disproportionately debilitating for marginalized social groups. Numerous studies have examined racial/ethnic dimensions of disaster vulnerability, but few have focused on Hispanic immigrants. More research on Hispanic immigrants is needed, since they constitute a major component of the Hispanic population—the largest and fastest‐growing minority group in the U.S.—and because they experience distinctive cultural and immigration status disadvantages. We examine the flood/hurricane vulnerabilities of Hispanic immigrants in comparison to U.S.–born Hispanics and non‐Hispanic whites. Using mixed methods to analyze data from 429 surveys and 31 interviews with residents living in flood zones, we examine differences in self‐protective action, risk perception, and hazard knowledge between the three groups in Houston and Miami. Hispanic immigrants exhibited lower levels of self‐protection and hazard knowledge, and higher perceptions of risk, which reflects their heightened vulnerability. Risk‐reduction programs should target the particular vulnerabilities of Hispanic immigrants, and future studies should examine their vulnerabilities in other contexts.  相似文献