海水酸化和热应激对日本鼓虾氧化应激和能量代谢的影响

伴随着全球气候变化的日益加剧,过量CO₂排放所导致的海洋酸化和暖化现象已引起广泛关注。本研究设置了两个pH水平（pH 8.1和pH 7.6）和两个温度梯度（20.0和23.0℃）,以探讨海水酸化和温度升高对日本鼓虾（Alpheus japonicus Miers）氧化应激和能量代谢过程的影响。结果发现,海水酸化、热应激以及海水酸化和热应激复合胁迫能够诱导日本鼓虾产生不同程度的氧化应激现象,且海水酸化和热应激对过氧化氢酶（Catalase,CAT）活性、还原型谷胱甘肽（Glutathione,GSH）含量和还原型谷胱甘肽与氧化型谷胱甘肽比值（Glutathione/Oxidized Glutathione,GSH/GSSG）有交互作用;其中,海水酸化和热应激复合暴露导致鼓虾GSH含量较对照组水平降低了66.0%,GSH/GSSG比值降低为对照组水平的20.8%,而脂质过氧化水平则较对照组显著增加了51.4%。此外,海水酸化和热应激复合暴露能够导致日本鼓虾己糖激酶（Hexokinase,HK）活性的显著增强和蛋白质含量的显著降低,提示鼓虾通过调节糖酵解过程和能量储备来满足机体的能量代谢需求。上述结果表明,短期海水酸化和热应激暴露能够影响日本鼓虾的抗氧化防御体系、能量代谢过程以及能量储备能力,长期持续暴露可能会对其种群维持构成潜在威胁。     

基于联合生成–去除的水下图像增强方法

现有的基于深度学习的水下图像增强方法在仿真的水下图像上取得了良好的效果。但是,由于简化的仿真图像与复杂的真实图像之间存在较大差距,此类方法在处理真实水下图像时性能明显下降。为了解决真实水下图像增强问题,提出了一种联合生成–去除水下图像增强方法。该方法采用分解思路,将水下图像分解为干净的背景层和退化层,通过循环一致性损失和对抗性损失来更好地保留背景,进而实现真实图像和仿真图像之间的转换,既校正了图像颜色,又提升了图像对比度,实现良好的增强效果。实验结果表明,本方法在真实水下图像数据集上处理的结果,在色彩、纹理细节和清晰程度方面均优于现有的对比方法。     

直流电阻率法在洋戴河平原海水入侵识别中的应用

海水和淡水之间的显著电性差异使得直流电阻率法可用于识别和监测海水入侵。洋戴河平原不同海水入侵程度含水层,其电阻率呈现出显著分异,一般规律为:严重入侵(5Ω·m),轻度入侵(5～13Ω·m),未入侵(13～150Ω·m)。结合水文地质钻孔资料,依靠含水层电阻率分布识别海水入侵。结果表明,洋戴河平原部分地区海水入侵进程具有明显的季节效应,由于农灌开采地下水导致6月海水入侵程度较为严重,3、11月海水入侵程度相对较弱。研究区滨海浅层地下咸水(微咸水)区主要分布在河道两侧,并向周围抽水灌溉区发展,其主要来源是海水沿河床入侵后形成的混合咸水以及灌溉回归水。现有的措施已经对海水入侵发展起到了一定的减缓作用,但仍需加强典型地段的防治。     

Observations of near-inertial waves induced by parametric subharmonic instability

Near-inertial waves(NIWs), which can be generated by wind or the parametric subharmonic instability(PSI) of internal tides, are common in the South China Sea(SCS). Moored current observations from the northern SCS have revealed that the PSI of semidiurnal(D_2) internal tides is another source of NIWs. The objective of this study was to examine the energy variance in the PSI of D_2 tides. The PSI of D_2 internal tides generated NIWs and waves with frequencies around the difference frequency of D_2 and f. The observed NIWs induced by PSI could be distinguished clearly from those elicited by typhoon Krosa. Shortly after Krosa entered the SCS, NIWs began to intensify on the surface and they propagated downward over subsequent days. The near-inertial currents were damped quickly and they became relatively weak before the waves were reinforced beneath the mixed layer when wind stress was relatively weak. Rotation spectra indicated an energy peak at exactly the difference frequency D_2–f of the NIWs and D_2, indicating nonlinear wave-wave interaction among D_2, f, and D_2–f. Depth-time maps of band-pass fi ltered velocities of D_2 –f showed the waves amplifi ed when the NIWs were reinforced, and they intensifi ed at depths with strong D_2 tides. The energies of the NIWs and D_2 –f had high correlation with the D_2 tides. The PSI transferred energy of low-mode D_2 internal tides to high-mode NIWs and D_2–f waves. For the entire observational period, PSI reinforcement was observed only when mesoscale eddies emerged and when D_2 was in spring tide, revealing a close connection between mesoscale eddies and NIWs. Mesoscale eddies could increase the energy in the f-band by enhancing the PSI of D_2 internal tides. Thus, this represents another mechanism linking the energy of mesoscale eddies to that of NIWs.     

Seasonal variation and modal content of internal tides in the northern South China Sea

A nine-month mooring record was used to investigate seasonal variation and modal content of internal tides(ITs) on the continental slope in the northern South China Sea(SCS). Diurnal tides at this site show clear seasonal change with higher energy in winter than in spring and autumn, whereas semidiurnal tides show the opposite seasonal pattern. The consistency of ITs with barotropic tides within the Luzon Strait, which is the generation region of the ITs, implies that the seasonal variation of ITs depends on their astronomical forcing, even after extended propagation across the SCS basin. Diurnal tides also differ from semidiurnal tides in relation to modal content; they display signals of high modes while semidiurnal tides are dominated by low modes. Reflection of the diurnal tides on the continental slope serves as a reasonable explanation for their high modes. Both diurnal and semidiurnal tides are composed of a larger proportion of coherent components that have a regular 14-day spring-neap cycle. The coherent components are dominated by low modes and they show obvious seasonal variation, while the incoherent components are composed mainly of higher modes and they display intermittent characteristics.     

基于TIN模型的水下地形匹配定位算法

针对当前尚无直接利用海图水深构建不规则三角网(triangulated irregular network,TIN)进行水下地形匹配定位的现状,提出了一种基于TIN模型的水下地形匹配定位算法。首先,在经典TERCOM(terrain contour matching)算法的基础上,设计基于TIN模型的匹配搜索区的确定方法;然后,给出待匹配航迹点的水深值计算公式;最后,构建目标匹配定位的地形相关组合算子,实现匹配定位。实验结果表明:(1)本文所提算法可以用海图的原始水深直接构TIN模型作为匹配基准图进行匹配定位,且其定位精度可明显高于基于规则格网模型的经典TERCOM算法;(2)新方法可以有效的降低误匹配的发生;(3)提出的MMD+MSD组合匹配算子能够一定程度上克服水深系统误差对定位精度的影响。     

工程影响下长江口涨潮槽演变特征研究--以北港六滧涨潮槽为例

崇明岛南岸发育有六滧涨潮槽,研究其演变过程对于崇明世界级生态岛港口建设、通航安全和岸滩稳定具有重要意义。为此,在长江口北港中上段2000、2004、2008、2012和2018年海图水深数据的基础上,分别于2018年7月利用SeaBat 7125、2019年7月利用M80无人艇搭载的SeaBat T50-P多波束测深系统以及ADCP对六滧涨潮槽开展了水下地形和流速的测量工作,分析工程影响下六滧涨潮槽的演变特征。结果表明:六滧涨潮槽淤浅,外侧沙脊冲刷剧烈,槽内落潮优势明显。其原因为流域来沙减少、以青草沙水库为主体工程的南北港分流口整治及长江大桥的修建导致了北港中上段主槽冲刷、主流北移。同时,六滧涨潮槽局部水动力条件增强,槽内的丁坝坝头局部冲刷加剧,并且奚家港东侧岸滩出现侵蚀,需引起重视。     

水位变动条件下二元结构岸坡稳定性分析——以扬中市指南村崩岸段岸坡为例

以指南村崩岸段岸坡为研究对象,通过实地调查开展地质钻探工作,获取岸坡土体的物理力学参数,并基于饱和-非饱和土渗流理论、非饱和土抗剪强度理论及极限平衡法,研究江水水位变动过程中二元结构岸坡稳定性的变化.结果 表明:①岸坡土体为二元结构,上层为粉质黏土,下层为粉砂,粉砂层厚度较大且透水性较好,为地下水流动提供良好环境.②水...     

哈维氏弧菌可视化LAMP快速检测方法的建立及应用

【目的】为加强对哈维氏弧菌（Vibrio harveyi）的早期快速诊断和筛查,探究一种快速检测方法。【方法】以哈维氏弧菌外膜通道蛋白基因Toic为靶基因,以钙黄绿素为检测结果指示剂,通过对反应体系、反应时间和温度进行优化,并检测其特异性和灵敏度,建立一种针对哈维氏弧菌的可视化环介导等温基因扩增（LAMP）检测方法。【结果】该方法的检测时间最快为35 min,灵敏度为100 fg/mL,特异性强,与8种弧菌及金黄色葡萄球菌均无交叉反应。实用性检测结果显示,该方法可准确并特异性地检测到鱼体组织中感染的哈维氏弧菌。【结论】建立一种设备简单、操作简单、反应快速、特异性强、灵敏度高、结果可视化的哈维氏弧菌LAMP快速检测方法,且适用于石斑鱼（Epinephelus）感染哈维氏弧菌的早期快速诊断,为进一步推广该技术在石斑鱼及其他水生动物哈维氏弧菌感染监测中的现场大规模应用提供技术支撑。