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长江口外缺氧区柱样沉积物元素的分布及其百年沉积环境效应 总被引:4,自引:0,他引:4
在210Pb定年的基础上,对取自长江口外缺氧区内外的柱样沉积物开展了10种常量元素、13种微量元素和粒度的测定分析,研究了其物源及分布特征。结果表明,缺氧区外柱样沉积物主要来源于老黄河口海岸泥沙,大部分元素具有"粒度控制"规律。缺氧区内沉积物主要来源于夏季长江陆源的输入和海洋自生生物死亡后的沉降,部分氧化还原敏感元素(RSE)和亲生物元素不受控于"粒控效应",其中Mo、Cd、As等氧化还原敏感元素自20世纪70年代以来明显富集,分别增加了83%、73%和50%,而Mn出现贫化,指示了缺氧区水体富营养化加剧和底层水体季节性缺氧,引起底层水-沉积物界面氧化还原环境变化;亲生物元素Ca、Sr、P含量自20世纪70年代起分别增加了129%、65%和38%,反映了受化肥使用等人类活动影响,近40年来长江口外水体生产力提高和生物量增加。 相似文献
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自2004年承担第一个908专项任务至今,国家海洋局第二海洋研究所共承担了局908专项调查研究课题10项(调查类7项,评价类3项),收到专项资金1 997万元。此外还承担了专项技术规程的编写及专项前期的各项准备工作。两年的时间中,海洋二所的908专项一直以“质量第一”为宗旨,尽心尽力 相似文献
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海洋中的鱼、贝、虾类等所含蛋白质、微量元素及维生素,是陆地动植物所不能比拟的[1]。然而由于加工和保鲜技术跟不上,导致大量水产品腐败变质,造成资源极大的浪费。世界渔业协会有关统计资料分析表明,近年来尽管全世界的水产品总产量已起过108t,但每年因变质而被丢弃的水产品至少占12 %以上,另有36 %的低值鱼被用作动物饲料,真正供给人类食用的仅为总产量的一半。作为水产品产量连续8年居世界第一的我国,据报道水产品加工仅占水产总量的30.7%[2,3],真正用于食用的水产品尚不足一半。为了让海洋资源更大效益… 相似文献
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Phytoplankton productivity and community structure in marginal seas have been altered significantly during the past three decades, but it is still a challenge to distinguish the forcing mechanisms between climate change and anthropogenic activities. High time-resolution biomarker records of two 210Pb-dated sediment cores(#34: 28.5°N, 122.272°E; CJ12-1269: 28.861 9°N, 122.515 3°E) from the Min-Zhe coastal mud area were compared to reveal changes of phytoplankton productivity and community structure over the past 100 years. Phytoplankton productivity started to increase gradually from the 1970 s and increased rapidly after the late 1990 s at Site #34; and it started to increase gradually from the middle 1960 s and increased rapidly after the late 1980 s at Site CJ12-1269. Productivity of Core CJ12-1269 was higher than that of Core #34. Phytoplankton community structure variations displayed opposite patterns in the two cores. The decreasing D/B(dinosterol/brassicasterol) ratio of Core #34 since the 1960 s revealed increased diatom contribution to total productivity. In contrast, the increasing D/B ratio of Core CJ12-1269 since the 1950 s indicated increased dinoflagellate contribution to total productivity. Both the productivity increase and the increased dinoflagellate contribution in Core CJ12-1269 since the 1950–1960s were mainly caused by anthropogenic activities, as the location was closer to the Changjiang River Estuary with higher nutrient concentration and decreasing Si/N ratios. However, increased diatom contribution in Core #34 is proposed to be caused by increased coastal upwelling, with higher nutrient concentration and higher Si/N ratios. 相似文献