西太平洋Y3海山对营养盐的影响及其生态环境效应

作为大洋典型地貌特征的海山,其邻近的海洋生境并不被人熟知。依据2014年冬季对热带西太平洋Y3海山及其邻近海域的综合调查,首次探讨了该海山区海水中营养盐的分布特征及其与生态环境的耦合关系。结果表明Y3海山区是典型的热带寡营养海域。在50~125 m的深度,温跃层和高盐区双重作用对底部高浓度营养盐向上输送的阻碍,是导致真光层上部营养盐浓度较低的重要原因;同时,浮游植物和异养细菌的消耗也加剧了该区域营养盐的缺乏。Y3海山突出的地形地貌对营养盐的分布产生重要的影响,海山对流经的海流产生阻碍,形成上升流,使底部高浓度的营养盐突破温跃层和高盐区的阻碍向上输送,从而使海山周围营养盐的平均浓度高于远离海山的海域。相关性分析显示,Y3海山区真光层中营养盐浓度与温度、盐度、叶绿素a浓度和异养细菌丰度分别呈负相关、正相关、负相关(除NO₂-N外)和负相关关系。海山区特殊的营养盐分布及其与生态环境的耦合是其成为一种独特的大洋生态系统的重要因素。     

胶州湾沉积物-海水界面硅的交换速率及其影响因素探讨

采用实验室培养法在原位温度和溶氧条件下测定了胶州湾沉积物-海水界面硅的交换速率,并探讨了相关环境因子对界面交换速率的影响机制。结果表明,胶州湾沉积物-海水界面硅的交换表现为从沉积物向水体释放,其交换速率在947~4 889 μmol/（m2·d）范围内,平均速率为1 819 μmol/（m2·d）。表层沉积物中叶绿素a（Chl a）和总有机碳（TOC）是影响胶州湾沉积物-海水界面硅交换速率的主要环境因子,同时表层沉积物的含水率（φ）、生源硅（BSi）和粘土含量以及间隙水中溶解硅酸盐（DSi）对沉积物-海水界面硅的交换也有重要影响。由此可推知,胶州湾沉积物-海水界面硅的交换速率主要受生物活动和溶解-扩散双重过程调控,而表层沉积物粒度与底层水体中DSi对胶州湾硅的释放影响较小。     

基于磷脂脂肪酸的热带西太平洋沉积物生源要素矿化过程探析

甄别生源要素参与的海洋沉积物矿化过程对探析生源要素的生物地球化学循环有重要的作用,矿化作用包括有氧呼吸、硝酸盐还原、铁锰异化还原及硫酸盐还原等多个过程,但如何区分这些过程一直是海洋沉积物矿化研究的难点。本研究采用气相色谱-质谱(GC-MS)联用对热带西太平洋沉积物中的磷脂脂肪酸(phospholipid fatty acid, PLFA)的组成进行了解析,并分析不同矿化过程中的主要PLFA种类及其影响因素,探究PLFA对沉积物矿化的指示作用。结果表明,PLFA总量在有氧呼吸过程中最高,而在硝酸盐还原过程中最低;且14:0、i14:0、i15:0和i19:0是有氧呼吸过程中微生物PLFA的主要组成,当其含量明显降低时可以指示沉积物矿化从有氧呼吸转变为硝酸盐还原;而10:0、17:0、20:0和22:0含量之和显著增加时则指示了硫酸盐还原过程的发生。在热带西太平洋沉积物中,总有机碳(TOC)和总有机氮(TON)含量以及间隙水NO₃-N含量是PLFA含量的重要影响因素,PLFA总量随着TOC和TON含量的减少而减少,并且TOC和TON的降解能够促进PLFA降解的发生,对PLFA组成有更直接的影响。     

CO2 flux and seasonal variability in the turbidity maximum zone and surrounding area in the Changjiang River estuary

The turbidity maximum zone(TMZ) is one of the most important regions in an estuary.However,the high concentration of suspended material makes it difficult to measure the partial pressure of CO_2(pCO_2) in these regions.Therefore,very little data is available on the pCO_2 levels in TMZs.To relatively accurately evaluate the CO_2 flux in an example estuary,we studied the TMZ and surrounding area in the Changjiang(Yangtze) River estuary.From seasonal cruises during February,August,November 2010,and May 2012,the pCO_2 in the TMZ and surrounding area was calculated from pH and total alkalinity(TA)measured in situ,from which the CO_2 flux was calculated.Overall,the TMZ and surrounding area acted as a source of atmosphere CO_2 in February and November,and as a sink in May and August.The average FCO_2was-9,-16,5,and 5 mmol/(m~2·d) in May,August,November,and February,respectively.The TMZ's role as a source or sink of atmosphere CO_2 was quite different to the outer estuary.In the TMZ and surrounding area,suspended matter,phytoplankton,and pH were the main factors controlling the FCO_2,but here the influence of temperature,salinity,and total alkalinity on the FCO_2 was weak.Organic carbon decomposition in suspended matter was the main reason for the region acting as a CO_2 source in winter,and phytoplankton production was the main reason the region was a CO_2 sink in summer.     

Geochemical Characteristics of Particulate Organic Carbon in the Kocebu Seamount Waters of the Western Pacific Ocean in Spring 2018

The study of the geochemical characteristics of the POC in the seamount area will be of great significance for further understanding the material cycle process in the seamount ecosystem. Based on a comprehensive survey of the Kocebu seamount in the Western Pacific Ocean in March, 2018, the distribution, source and composition of Particulate Organic Carbon (POC) in the seawater of the Kocebu seamount area were discussed. The results showed that the concentration of POC in the Kocebu seamount area gradually decreased with the increasing water depth, and slightly rose in the water layers near the bottom of the seamount. The average concentration of POC in each water mass was sorted from high to low in the order of North Pacific Tropic Water, North Pacific Intermediate Water and Deep Water (DW), and the concentration of POC at stations near the seamount summit was lower than that far from the seamount in the DW. There was upwelling at the water layers of 750~1 500 m above the seamount summit, causing the uplift of the 12.50 μg/L POC isoline in this region, however, no “seamount effect” was formed. The POC was mainly imported from the sea with an average POC/PON of 3.75. At the water layers of 0~300 m, only the POC/chlorophyll a (Chl a) at deep chlorophyll maximum layer was less than 200, indicating that the POC in this region was mainly in a form of life, while at the water layer of 300 m, the POC/Chl a increased sharply, indicating that the non-living POC contributed the most to the total POC.     

2020年秋季渤海的健康状况与海域开发利用建议

为获取渤海最新的健康状况,文章基于新构建的以海洋生态环境自身状态为内核、以人类社会经济学指标为外核的“双核”评价体系,对渤海2020年秋季的海洋健康状况进行综合评价。内核评价结果显示,2020年秋季渤海的水体环境和沉积环境整体较为健康,仅中心区域水质略差,而海洋生物群落的健康状况一般,整个研究区域仅58.9%的区域评级为“优”,因此该海域总的内核评级为“良”;以分别代表海洋第一、二、三产业的海洋渔业、海洋油气业和海洋交通运输业作为外核指标的评价结果显示,渤海的外核得分为0.95。因此,所调查的渤海中西部海域海洋生态环境健康状况的“双核”评价结果为“良+0.95”,表明该区域的海洋生态环境目前整体上处于较健康的状态,但人类对渤海海洋资源环境的开发力度接近饱和,且局部海区的生态环境健康状况已经出现了恶化,需要对该海区进行密切监测。建议通过优化产业结构和提升开发技术等方式,尽可能降低经济开发活动对海洋生态环境的影响,以实现渤海海洋资源环境的可持续利用。     

Impact of Kuroshio on the dissolved oxygen in the East China Sea region

A marine survey was conducted from 18 May to 13 June 2014 in the East China Sea(ECS)and its adjacent Kuroshio Current to examine the spatial distribution and biogeochemical characteristics of dissolved oxygen(DO) in spring. Waters were sampled at 10-25 m intervals within 100 m depth, and at 25-500 m beyond 100 m. The depth, temperature, salinity, and density(sigma-t) were measured in situ with a conductivity-temperature-depth(CTD) sensor. DO concentrations were determined on board using traditional Winkler titration method. The results show that in the Kuroshio Current, DO content was the highest in the euphotic layer, then decreased sharply with depth to about 1 000 m, and increased with depth gradually thereafter. While in the ECS continental shelf area, DO content had high values in the coastal surface water and low values in the near-bottom water. In addition, a low-DO zone of f the Changjiang(Yangtze) River estuary was found in spring 2014, and it was formed under the combined influence of many factors, including water stratification, high primary productivity in the euphotic layers, high accumulation/sedimentation of organic matter below the euphotic layers, and mixing/transport of oceanic current waters on the shelf. Most notable among these is the Kuroshio intruded water, an oceanic current water which carried rich dissolved oxygen onto the continental shelf and alleviated the oxygen deficit phenomenon in the ECS, could impact the position, range, and intensity, thus the formation/destruction of the ECS Hypoxia Zone.     

台湾以东黑潮沉积物中的生源要素对近千年来气候环境变化的响应

基于台湾以东黑潮主流系沉积物中碳、氮、磷等生源要素指标的变化,在沉积物年代学的基础上,探讨了近千年来气候环境变化在黑潮沉积物中的历史记录。结果表明,近千年来台湾以东、琉球岛弧南侧斜坡的黑潮主流区平均沉积速率可达34.2 cm/ka,据其变化可大致分成的3个沉积阶段,与中世纪暖期、小冰期和现代暖期的划分基本一致。沉积物中碳以无机碳为主,总无机碳（TIC）的含量从1850年开始逐渐增大并伴随剧烈波动,恰好与大气CO₂水平的快速升高相对应;总有机碳（TOC）含量的变化则与东亚夏季风强度的变化关系密切,在夏季风较弱的小冰期其含量明显高于夏季风较强的中世纪暖期和现代暖期,这是由于较弱的夏季风有利于亚洲大陆风尘的产生和向海输送,从而促进了研究海域的初级生产力。1850年以来,沉积物中的C∶N∶P逐渐从低于转变为高于Redfield比,反映了上层水体营养盐结构从氮缺乏到氮充足的转变,这与近现代以来急剧增加的全球氮排放密切相关。总体来说,黑潮主流系沉积物中的生源要素指标,明确记录和响应了近千年来的气候环境变化,尤其是近150多年以来不断加剧的人类活动所造成的气候环境剧变。     

胶州湾沉积物中氨基酸对有机质降解及细菌源贡献的指示作用解析

基于对胶州湾表层沉积物中总可水解氨基酸（THAA）的含量、组成、构型及分布特征的系统研究,通过氨基酸碳氮归一化产率（THAA-C%,THAA-N%）、降解因子DI、反应活性指数RI以及D型氨基酸占比（D-AA%,摩尔百分比）等指标结合碳氮比（TOC/TN）、碳稳定同位素（δ13C）探析了胶州湾沉积物中有机质的来源与降解状态,利用细菌源有机质及胞外肽酶活性（EEA）探讨了微生物在有机质迁移转化过程中的作用与贡献。结果表明,胶州湾表层沉积物中氨基酸平均含量为（7.60±3.64）μmol/g,在陆源与海源混合影响下,其水平分布呈现湾内高于湾外、湾内东部高于西部的特点,表明湾内东部陆源输入对沉积物THAA具有较高贡献。THAA-C%、THAA-N%、DI、RI以及D-AA%等指示因子均显示胶州湾表层沉积物中有机质的降解程度呈现湾外高于湾内、湾内东部高于西部的变化趋势,有机质来源、微生物活性与上覆水水深共同影响了有机质的降解程度。胶州湾表层沉积物中细菌源有机碳的贡献率为（29.35±18.73）%,其水平分布显示出湾内西部与湾外相近且高于湾内东部的特点。细菌胞外肽酶活性（EEA）平均为（0.81±1.31）nmol/（g·h）（以MCA计）,整体分布趋势与细菌贡献率相反,呈现湾内东部高于湾内西部和湾外的特性。沉积物中有机质的不同海源、陆源占比决定了有机质的可降解性,而有机质的降解程度进一步影响了细菌源有机质的贡献与胞外肽酶活性。