Antarctic krill (Euphausia superba) are the key species of the ecological system in the Cosmonaut Sea. Long-term habitat alterations in krill due to climate change have been considered in recent decades. However, there is still a lack understanding about krill distribution. The MaxEnt model was used to forecast the suitable distribution area of krill for this study, which is based on data from the Coupled Model Intercomparison Project in its sixth phase (CMIP6) in the near future and far future. A total of 145 occurrence points and 15 environmental factors were selected to build the MaxEnt model. The current suitable habitat regions for krill were mostly detected in the western and central regions of the Cosmonaut Sea, which accounted for 10.07% of the total area. The most important environmental variables that influenced krill distribution were minimum surface solar radiation downward (ssrdmin), the mean temperature (tem) and the mean northward velocity (v). In the near future and far future, the suitable area of krill was seen to decline under all shared socioeconomic pathways (SSPs), with the smallest reduction under SSP1-2.6 and the greatest reduction under SSP5-8.5. The suitable area for krill dropped quicker from the near future to the far future than the present to the near future. Krill habitats were expected to shift to the poles. The tem continued to rise in the future under all SSP scenarios, particularly under the high radiative forcing scenario. The increase in water temperature is the main reason for the decrease in suitable areas for Antarctic krill. Our results show the future distribution of krill in the future and provide a reasonable reference for the ecological protection policy of the Cosmonaut Sea.
水下滑翔机定位与导航精度的提高对于其完成水下作业任务至关重要.水下滑翔机传统的定位方法是依托于GPS信息的航位推算,定位精度较低,不能满足按既定路径航行的导航要求.为此,本文提出了一种利用卡尔曼滤波的组合导航方法,该方法在传统航位推算技术的基础上采用卡尔曼滤波器融合惯性导航系统数据和深度计数据,得出深度的卡尔曼最佳估计值,以此代替传统航位推算技术中的深度计直接测量值,从而提高航位推算精度.基于该方法,进行了仿真分析,并通过样机水池实验验证了该方法的有效性.
本文探索在海水中施氮、磷肥对条斑紫菜生长、总蛋白氨基酸与游离氨基酸(FAA)含量及组成的影响.试验设4项处理培养条斑紫菜:以自然海水作为对照、单施氮肥、单施磷肥及氮肥与磷肥配合.结果显示:单施氮肥能略促进条斑紫菜的生长,并显著促进总氨基酸含量和FAA含量的增加;单施磷肥显著促进条斑紫菜生长,但使总氨基酸含量降低,FAA含量也显著低于单施氮肥组和氮肥与磷肥配合施用组;氮肥与磷肥配合施用,条斑紫菜生长的相对生长率最高,条斑紫菜的总氨基酸含量和FAA含量也显著增加,并使呈味氨基酸增加,改善条斑紫菜食用品质.所以氮肥和磷肥配合施用,对条斑紫菜生长和品质改善具有互助效应.
饮用水处理的消毒副产物问题已有大量研究,压载水处理引入的消毒副产物给环境带来的安全隐患正在受到各国专家及国际海事组织IMO的关注,消毒剂、水中的有机物及盐度是影响消毒副产物产生的主要因素,相关的毒性研究也在开展;获得1MO最终批准的45项使用活性物质的压载水管理系统使用不同的处理技术产生的消毒副产物总量也不尽相同,同一种技术不同系统消毒副产物产生的总量差别较大;虽然使用活性物质的压载水管理系统在递交IMO认可时需要完成风险评估,但沿用现有评估模型对实际港口评估时,某些物质仍对环境有不可接受的风险,各港口地理及水质条件的复杂性、毒理数据的不足、相关检测技术的限制等都是现有评估标准使用受限的原因.随着相关研究的开展以及IMO对消毒副产物的持续关注,不久的将来很有可能会出现更加严苛的限制指标.《公约》的强制实施,压载水管理系统加装市场会迎来大批订单,随压载水处理引入的消毒副产物问题会被凸显出来,因此船东加装压载水管理系统时对技术的选择尤为关键,更加绿色安全的压载水处理技术应尽快实施应用在压载水处理领域.
根据2014年5月(春)、10月(秋)2个航次在渤海湾黄骅港海域开展的渔业资源底拖网调查数据,利用相对优势度指数、聚类分析、非度量多维标度分析(NMDS)和ABC曲线等方法,对该海域渔业资源的种类组成、优势种和平均资源密度等群落结构特征进行了分析.结果显示,两次调查共捕获渔业资源48种,主要由26种鱼类、18种甲壳类和4种头足类组成.春季优势种主要为口虾蛄等甲壳类,秋季虾虎鱼类的优势度较高.春季该海域渔业资源的平均资源密度为13.16 kg/h,秋季平均资源密度为14.87 kg/h,渔业资源空间分布不均匀.与春季相比,秋季渔业资源的生物多样性较高,秋季群落结构受干扰程度也较高.本研究揭示了黄骅港海域渔业资源的结构特征,可为渔业资源的修复和养护提供理论依据,为港口工程的建设提供科学支撑.
