Black Carbon (BC) and the Global Carbon Cycle: Assessing BC Inventories in Coastal Seawater and Burial in Margin Sediments off the Northeastern USA

在过去的世纪里，作为化石燃料和生物质不完全燃烧的产物，黑碳（BC）已经越来越多地形成并释放到环境中。目前，无法量化（a）BC在大洋边沉积物中的埋藏率（大部分OC被埋藏在那里），（B）海水中BC储存的规模，也无法量化（c）BC流入海洋的河流通量。因此，无法确定BC对全球碳循环的重要性。根据该奖项，PI解决了以下问题：（1）在缅因州湾，BC埋藏相对于有机碳埋藏的贡献是什么？(2)在过去的世纪中，BC对该地区河床沉积物的输入通量发生了怎样的变化？(3)美国东北部沿海海水中BC的库存是什么？这个水库表现出什么样的时空变化？(4)BC到缅因州海湾的河流输入是什么？它们是如何随季节变化的？(5)我们能否确定BC的主要来源（例如，化石燃料燃烧产生的烟尘，生物质衍生的焦炭）的沿海海水和沉积物的缅因州？除了测量各种样品中的BC丰度外，所采取的方法还包括对水和沉积物进行实地采样，以及各种分析测量，包括：水中234 Th/238 U不平衡和沉积物中无载体210 Pb、BC中碳同位素和特定化合物以及关键标志化合物（PAHs），从缅因州海湾内外收集的放射性测年沉积物岩心中的碳同位素和碳同位素分析。

Black carbon (BC), the product of incomplete combustion of fossil fuels and biomass, has been increasingly formed and released to the environment for the last century. Presently, it is not possible to quantify (a) the rate of BC burial in the oceanic margin sediments (where most of the OC is buried), (b) the size of the BC reservoir in seawater, nor (c) riverine fluxes of BC to the sea. Consequently, it is not possible to ascertain how important BC is to the global carbon cycle. Under this award, the PIs address the following questions: (1)What is the contribution of BC burial relative to the organic carbon burial in the Gulf of Maine? (2) How has the input flux of BC to the region's bed sediments changed in the past century? (3) What is the inventory of BC in coastal seawater off the Northeast United States and what temporal and spatial variability does this reservoir exhibit? (4) What are riverine inputs of BC to the Gulf of Maine and how do they vary seasonally? (5) Can we identify the major sources of BC (e.g., fossil fuel combustion-produced soots, biomass-derived chars) for coastal seawater and sediment of the Gulf of Maine? In addition to measurement of the abundance of BC in various samples, the approach taken includes field sampling of water and sediments, and a variety of analytical measurements including: 234Th/238U disequilibria in water and unsupported 210Pb in sediments, carbon isotopes in BC and specific compounds as well as with key marker compounds (PAHs), and BC analyses in radiometrically dated sediment cores collected from within and beyond the Gulf of Maine.