Impact of the water-sediment regulation and a rainstorm on nutrient transport in the Huanghe River

Dissolved nutrient concentration in the Huanghe(Yellow) River at Lijin was monitored during a water-sediment regulation period and a subsequent rainstorm from 14 June to 19 July, 2005. This study provides detailed information on nutrient concentrations in the Huanghe River during the water-sediment regulation and rainstorm periods, and is of signifi cance for the downstream area of the Huanghe River and the Bohai Sea. The average concentrations of nitrate, nitrite and ammonia were 304.7 μmol/L, 0.19 μmol/L, and 1.10 μmol/L, respectively, while the average concentrations of dissolved inorganic phosphorus(DIP) and dissolved silicate(DSi) were 0.23 μmol/L and 122.9 μmol/L, respectively. Nutrient concentrations during the water-sediment regulation period were mainly infl uenced by the dilution effect, fl oodplain effect and sediment resuspension while dilution and erosion effects were the main factors during the rainstorm. The fl uxes of dissolved inorganic nitrogen(DIN), DIP and DSi during the water-sediment regulation and rainstorm periods accounted for 20.4%, 19.5%, 16.7% and 4.97%, 6.45%, 5.47% of the annual nutrient fl uxes, respectively. Discharge was the main factor infl uencing the fl uxes of nutrients during both the watersediment regulation and the rainstorm periods.     

港口与腹地供应链的协同效应分析

物流成本是影响地区贸易发展的重要因素,而腹地运输则是物流成本结构中比重最大的组成部分,因此,腹地运输效率的改善能够有效提升区域间的贸易活跃度。结果显示,公路运输价格的波动对供应链总运量具有短期效应,而铁路运输价格和港口装卸价格则表现出更多的外生性。同时,物流服务价格的提高会减少厂商在该腹地的货运总量,但物流服务提供商的规模以及服务的可靠性能够有效地降低运量对价格的敏感程度。     

中国将建设内蒙古东部新的煤炭出海南下大通道

新华社沈阳消息 在中国煤炭运输大港秦皇岛港附近的绥中县,将崛起一座新的亿吨级煤炭港区。这个新煤炭港区将成为辽宁省最大的煤炭运输港口,为内蒙古东部的煤炭资源出海南下提供支撑。     

Evaluation of a gravel transport sensor for bed load measurements in natural flows

A recent acoustic instrument （Gravel Transport Sensor, GTS） was tested for predicting sediment transport rate （bed load rate） in gravel bed streams. The GTS operation is based on the particle collision theory of submerged obstacles in fluids. When particles collide with the GTS cylinder their momentum is recorded in the form of ping rates. The GTS is attractive for further consideration here because of its potential to provide continuous unattended local bed load measurements, especially in areas found in streams that access may be difficult under extreme conditions. Laboratory experiments coupled with numerical simulations for the same flow conditions were performed in order to determine the conditions under which particles of different size will hit the GTS cylinder and be able to register a ping rate. The GTS was able to detect the number of particles with diameter in the range of 15.9 to 25.4 mm, with reasonable accuracy, if the applied Shields effective stress τ＊e = τ＊ - τ＊cr was in the range of 0.006 to 0.015. A drawback of the tested prototype GTS, however, was that it exerted increased resistance on the incoming particles. The added drag effects increased the overall resistance that was exerted by the flow on particles and thus increased the likelihood that particles will rest in the ambient region of the cylinder instead of hitting it. Numerical simulation of the flow around the GTS cylinder revealed that changing the prototype geometry from cylindrical to ellipsoid or rhomboid will increase the likelihood of the particles hitting the instrument under the same flow conditions failed by the original tested GTS cylinder.     

难进入地区钻探工程航空运输技术经济分析

论述了难进入地区钻探工程航空飞行运输方式,对直升机吊运的技术经济性进行了研究,认为在地质调查钻探施工作业中应用航空运输的客观条件已基本具备;航空器在钻探工程中的应用必将促进钻探装备技术的发展,标志着地质调查钻探作业水平进入了一个新的高度。     

密度胁迫对卵形鲳鲹鱼苗运输水质、存活率、免疫酶活力和血清指标的影响

为了研究密度胁迫对卵形鲳鲹(Trachinotus ovatus)鱼苗运输水质、存活率、免疫酶活力和血清生化指标的影响,确定适宜的运输密度,为卵形鲳鲹鱼苗的科学运输提供参考依据。对卵形鲳鲹鱼苗(体长为5.36cm±0.60cm,质量为3.04g±0.71g)采用塑料袋密闭充氧运输方式,在3个不同运输密度下(D1=9 kg/m~3、D2=12 kg/m~3、D3=15 kg/m~3)模拟运输8 h,对比运输不同密度卵形鲳鲹鱼苗对运输水质、鱼苗存活率、肝脏免疫酶活力和血液生理生化指标的影响程度。结果表明, 3个密度组的卵形鲳鲹鱼苗的存活率均为100%,经运输后暂养72 h的存活率仍为100%。经塑料袋密闭充氧运输8 h后, 3个密度组的运输水体的DO含量无显著变化,运输水体温度(T)和pH值随运输密度的增加而降低, NH_4-N含量随运输密度的增加而上升,其中NH_4-N的含量显著高于对照组。肝脏组织中, D1、D2、D3的总超氧化物歧化酶(T-SOD)活力无显著差异(P0.05,下同),而高运输密度组(D3)对比对照组,两组的T-SOD活力变化存在显著差异(P0.05)。密度运输胁迫组乳酸脱氢酶(LDH)活力显著高于对照组水平,D2、D3无显著差异,显著差异于D1组。过氧化物酶(POD)活力D1、D2、D3组无显著差异,但均显著低于对照组。3组实验组的过氧化氢酶(CAT)活力均显著高于对照组且组间无显著差异。血清中, D1、D2组的CRE活力显著低于对照组,但D3组又显著高于对照组。D1、D2、D3的血清中皮质醇(COR)活力无显著差异,但显著高于对照组。D2、D3的葡萄糖(GLU)含量与对照组无显著差异, D1显著低于对照组。D1、D2、D3 3个运输密度组的谷丙转氨酶(GPT)与谷草转氨酶(GOT)活力均显著高于对照组。同时, D1与D2组的GPT活力显著低于于D3组,但GOT活力显著高于D3组。密度胁迫对卵形鲳鲹鱼苗的运输存活率无影响,但对运输其的水质、免疫酶活力及血清生化指标均有影响。在实际运输中,采用塑料袋密闭充氧运输,运输时间时长为8 h以内,运输密度设定为15 kg/m~3的卵形鲳鲹鱼苗为宜。     

“海上丝绸之路”沿线重要港口区位优势度评估

评估“海上丝绸之路”沿线港口的区位优势度,对于港口及其腹地基础设施合理规划、港口未来投资预判以及推进“一带一路”倡议有重要意义。本文从海陆联运的视角出发,综合考虑港口腹地的路网密度、交通干线影响度、城市影响度、航运战略枢纽影响度和航运战略通道影响度等五个因素,构建港口区位优势度评价模型来对“海上丝绸之路”沿线重要港口进行区位优势度分析。研究发现：① “海上丝绸之路”沿线港口的区位优势度区域化差异显著,从东向西总体呈“高-低-高”的空间分布格局;② 从世界分区的视角看,东南亚区域港口区位优势最高,其次为南欧至西欧、南亚、北非、西亚等地区,东非至南非区域港口区位优势度最低;③ 港口各区位影响因素的评价结果空间分布特征差异显著,其中港口区位优势度分布特征与交通干线影响度、城市影响度的相关性较大。研究结果可为海外港口基础设施的投资建设过程提供科学支撑。     

MS-222对大黄鱼(Larimichthys crocea)麻醉保活运输效果研究

为优化大黄鱼(Larimichthyscrocea)麻醉运输技术,提高保活率,以不同浓度MS-222麻醉剂对其运输存活率、呼吸代谢、鱼体生理生化指标的影响展开研究。结果显示:(1) 12 h模拟运输后,10mg/L麻醉组大黄鱼存活率显著高于其他实验组(P<0.05),30mg/L麻醉组积累死亡率已高于50%;(2)呼吸频率随麻醉剂浓度的升高显著降低(P<0.05),各组水体溶解氧含量随运输时长增加均呈下降趋势;(3) 10和20 mg/L麻醉组大黄鱼复苏率分别为89%±10%和63%±19%,且均显著高于30 mg/L麻醉组(P<0.05);(4)随麻醉剂浓度的升高,大黄鱼血清中皮质醇、谷草转氨酶、乳酸脱氢酶、葡萄糖-6-磷酸酶水平逐渐降低,其肌肉乳酸水平显著降低(P<0.05),其肌糖原水平显著升高(P<0.05)。结果表明:高浓度(30mg/L)MS-222处理会引起大黄鱼呼吸抑制,造成运输存活率下降,不适合应用于大黄鱼的保活运输;低浓度(10mg/L)MS-222处理可以达到降低鱼体拥挤胁迫、应激反应及呼吸代谢的效果,并可以有效降低大黄鱼死亡率,保活...     

基于熵的瓶颈运输问题的动态规划解

建立了关于时间(路程)的瓶颈运输问题的动态规划模型,并利用熵作为工具,解决了物品运输过程中所用时间长短的界问题,进而给出易于处理的瓶颈运输问题的动态规划模型。最后给出一个实例说明该方法的实用性和有效性。     

中日海运发展动向

进入80年代末(90年代初),世界经济区域化、国际贸易集团化取得了明显进展,同时国际分工越来越细,国际间贸易摩擦不断扩大。为减少乃致避免与美国和欧洲的贸易摩擦,日本不得不重新考虑其经济发展战略,从“脱亚入欧”转为“脱欧入亚”,为中日贸易迅速发展提供了前提条件。据中国海关统计1993年1～8月份我国对日贸易高达211亿美元,比上年同期