Marine sediments as archives of past climate and recent anthropogenic changes

海洋沉积物作为过去气候和近期人为变化的档案

• 批准号: RGPIN-2018-05607
• 负责人: Kienast, Stephanie
• 金额: $ 1.82万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=655519
• 关键词: Marine; sediments; archives; past; climate

Dust aerosols play a direct role in Earth's energy balance by scattering as well as absorbing radiation. Mineral dust and its associated nutrients also fertilize ecosystems and thus influence climate indirectly via photosynthesis and carbon uptake. However, large gaps exist in our understanding of the global dust cycle, in part due to the severe lack of direct observations of dust deposition in present and past environments. Mineral dust and its effect on radiative forcing and future climate have been identified as critical areas of research by the Intergovernmental Panel on Climate Change (IPCC). The first objective of this proposal is to investigate how much dust was deposited where, at what time, and from which sources, and whether changes in dust deposition caused changes in phytoplankton productivity and carbon removal from the upper ocean-atmosphere system. We combine measurements of a novel radioisotope tracer (232Th) with other geochemical proxies in marine sediment cores to generate new paleo records of dust deposition and organic carbon fluxes in the global ocean. The results are compared to simulations of state-of-the-art coupled climate models, such as the Community Climate System Model (CCSM), which are used in climate change scenarios by the ICPP and provide time slice as well as transient targets for hindcasting studies of the dust cycle. Research related to this objective generates critical new knowledge on the dust and carbon cycles in the undisturbed atmosphere-ocean system of the past, which is a recognized pre-requisite for the accurate prediction of future climate conditions. ******In addition to recording past environmental conditions, marine sediments act increasingly as a sink for pollutants from human activities, especially in coastal areas. Using highly similar geochemical tools as above, the second objective of this research program is to investigate metal fluxes in coastal sediments near finfish aquaculture operations. Canadian aquaculture production has expanded fourfold since the 1990's, reaching ~187,000 tonnes worth $967 million in 2015. However, aquaculture related activities appear to cause increased accumulation of harmful metals, such Cu and Zn, in underlying sediments. We will analyze metal fluxes in coastal sites that are proximal and distal to finfish aquaculture operations and compare observed levels with baseline values (pre-Anthropocene, pre-industrial). We will test whether metal concentrations exceed Probable Effect Levels (PEL) identified by the Canadian Council of Ministers of the Environment. If so, we will investigate whether there is a risk of metal re-mobilization back into the water column. Research related to objective 2 generates new insight that will advance our understanding of environmental sustainability in coastal areas and contribute to sustainable resource extraction in Canada. *****

尘埃气溶胶通过散射和吸收辐射在地球的能量平衡中发挥了直接作用。矿物灰尘及其相关的营养也可以施肥生态系统，从而通过光合作用和碳吸收间接影响气候。但是，我们对全球尘埃周期的理解中存在很大的差距，部分原因是在当前和过去的环境中严重缺乏直接观察到尘埃沉积。政府间气候变化小组（IPCC）将矿物灰尘及其对辐射强迫和未来气候的影响已确定为研究的关键领域。该提案的第一个目的是研究在何处，什么时间以及从哪些来源中沉积了多少灰尘，以及灰尘沉积的变化是否导致浮游植物生产率的变化和从上海洋上游系统中去除碳。我们将新型放射性同位素示踪剂（第232）与海洋沉积物核中的其他地球化学代理结合在一起，以在全球海洋中产生新的尘埃沉积和有机碳通量的古记录。将结果与最先进的耦合气候模型的模拟进行了比较，例如社区气候系统模型（CCSM），这些模型在气候变化场景中被ICPP使用，并提供时间切片以及瞬态目标，用于尘埃周期的后播研究。与该目标相关的研究产生了关于过去不受干扰的大气 - 海洋系统中尘埃和碳循环的关键知识，这是对未来气候条件进行准确预测的公认的先决条件。 ******除了记录过去的环境条件外，海洋沉积物还越来越多地作为人类活动（尤其是在沿海地区）的污染物的水槽。使用与上述高度相似的地球化学工具，该研究计划的第二个目标是研究Finfish鱼类水产养殖业务附近沿海沉积物中的金属通量。自1990年代以来，加拿大水产养殖产量已扩大了四倍，在2015年达到约187,000吨价值9.67亿吨。但是，在潜在的沉积物中，与水产养殖相关的活动似乎会导致有害金属的积累增加，例如CU和Zn。我们将分析沿海近端且远端的沿海水产养殖操作的金属通量，并将观察到的水平与基线值（人类新世之前，前工业化）进行比较。我们将测试金属浓度是否超过了加拿大环境部长理事会确定的可能效应水平（PEL）。如果是这样，我们将调查金属是否有重新安装在水柱中的风险。与目标2相关的研究产生了新的见解，这将提高我们对沿海地区环境可持续性的理解，并为加拿大的可持续资源提取做出贡献。 *****