Archive for category 学术活动 Research activities

海洋地质国家重点实验室东海综合科考夏季航次(KECES-2020)顺利完成

       2020年8月31日,“浙渔科2号”科考船抵达浙江舟山双阳码头,同济大学海洋地质国家重点实验室组织的2020年度长江口—东海陆架关键元素循环的综合科考夏季航次(KECES-2020: Key Elements Cycling in the Changjiang-Estuary-Shelf Transect)顺利完成。在苏妮副教授和连尔刚博士带领下,来自同济大学、厦门大学和上海海洋大学等单位的21名科考队员参加了科考任务。这也是继2019年夏季综合航次成功组织后的第二个KECES航次。

KECES-2020夏季航次全体科考人员合影

       航次通过多学科、多平台、多仪器的观测手段,系统探究长江口关键断面与海域的物质输运/多界面过程/关键元素循环及其沉积记录与环境效应等科学问题,为阐明人类活动和全球变化影响下世界特大河口海岸地区的长期变化过程和机理提供基础数据,为未来河口海岸环境演变预测提供科学支撑。这也是大科学工程——东海海底观测系统的关键目标之一。

KECES-2020夏季航次科考站位

      为期十天的航次期间,全体科考成员在做好疫情防护的同时,与台风“巴威”抢夺阵地与时间,共完成27个站位的CTD和大体积水体采样、浮游生物垂直拖网、沉积物短柱状采样、悬浮颗粒物采样等既定工作内容,成功捕获低氧长江口低氧事件,并获取了河口最大浑浊带、锋面内外及低氧核心区获取跨多个界面、不同氧化还原条件下的沉积记录和孔隙水剖面。航次还特别关注2020年6-7月长江大洪水对河口浮泥活动性、有机质埋藏和再矿化以及低氧的影响等科学问题。夏季航次的顺利完成为航次后综合研究和KECES冬季航次准备奠定了坚实基础。

文/王朔 连尔刚

AGU Eos Editors’ Highlight about CMS Group paper in JGR-ES!美国地球物理联合会会刊Eos以“编辑亮点”形式报道CMS课题组JGR-ES论文!

Eos is a source for news and perspectives about Earth and space science and run by AGU (American Geophysical Union). Eos Editors’ Highlights are part of a collection of some of the most interesting and impactful research published in AGU journals. Recently, our JGR-Earth Surface paper “Denudation rate changes along a fast‐eroding mountainous river with slate headwaters in Taiwan from 10Be (meteoric)/9Be ratios” was selected for Editors’ Highlights. This study was conducted via collaboration between Tongji University and Prof. Friedhelm von Blanckenburg and Dr. Hella Wittmann at German Research Centre for Geosciences (GFZ).

The novel 10Be (meteoric)/9Be system, where 10Be is delivered by precipitation and stable 9Be is released by weathering, provides denudation rates over weathering-erosion timescales. The new tool is applicable to quartz-poor lithologies, e.g. mafic rock and claystone, which are not readily accessible by the commonly used in situ-produced 10Be in quartz. We provide a first application of this proxy to a tectonically-active mountainous river, the Zhuoshui River in Taiwan. Taiwan Rivers supply a disproportionately high suspended and dissolved flux to the oceans and are often underlain by fine-grained shale/slate. 10Be (meteoric)/9Be-derived denudation rates (Dmet) from the Zhuoshui Catchment are highest in the slate-dominated headwaters (4-8 mm/yr), and much lower (1-2 mm/yr) along the mid-lower reaches with mixed lithologies. At the basin-wide scale, we find a poor correlation between Dmet and basin-averaged channel steepness despite a small climatic gradient. Because large lithological heterogeneities exist in this basin, we invoke a lithological effect to explain this poor correlation. Relying on a revised stream power incision model that incorporates rock erodibility, the resulting lithology- and runoff- adjusted ksn (kLrsn) can be reconciled with denudation rates with the highest erodibility predicted to prevail in the Miocene slate of low metamorphic grade and high fracture density. This model suggests that the lithological heterogeneity can alter the coupling between surface denudation and channel morphology. On a broader perspective, the successful application of the 10Be (meteoric)/9Be proxy shows its applicability as a tracer for erosion and sediment transport processes in fast-eroding mountain belts underlain by slate lithologies.

JGR-ES editor Mikael Attal wrote in “Editors’ Highlight”: “…This study bridges a significant gap: it demonstrates that meteoric 10Be can be used to quantify erosion rates in catchments with a range of lithologies exposed. It proposes a new framework to quantify differences in rock resistance to erosion and demonstrate their impact on landscape steepness, with implications for retrieving erosional signals from topographic data.”

Cite: Deng, K., Yang, S., von Blanckenburg, F., & Wittmann, H. [2020]. Denudation rate changes along a fast‐eroding mountainous river with slate headwaters in Taiwan from 10Be (meteoric)/9Be ratios. Journal of Geophysical Research: Earth Surface, 125, e2019JF005251.

Eos Editors’ Highlight:https://eos.org/editor-highlights/meteoric-10be-reveals-lithological-control-on-erosion-rates

Full article:https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JF005251