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Using geochemical tracers and mathematical models to estimate sinking particle interaction rate constants

机译：使用地球化学示踪剂和数学模型估算下沉颗粒相互作用速率常数

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This dissertation has three parts; all concern the behavior of sinking particles in the ocean; all data come from the MedFlux program.;Sinking particles play an important role in the oceanic biogeochemical cycle, because they are in the core position of the "biological pump" that is responsible for transporting photosynthesized organic matter and energy into the deep ocean. On the one hand, this transportation fuels benthic organisms; on the other hand, it reduces carbon dioxide partial pressure in the surface water and promotes absorption of elevated atmospheric carbon dioxide. Particle sinking velocity, which controls particle residence time in the water column as well as the efficiency of the biological pump. Particle aggregation and disaggregation can influence particle sinking velocity, because large particles sink faster than small particles according to Stokes' law.;Thorium data collected using Indented Rotating Sphere-Settling Velocity (IRS-SV) sediment traps during the MedFlux program were analyzed using two contrasting models. In both cases, the 11 settling velocity categories collected by these traps were optimally divided into two settling velocity classes ("slow" versus "fast") using maximum likelihood estimation. In the first analysis, particle aggregation, disaggregation, remineralization, thorium adsorption, and desorption rate constants were estimated using likelihood methods; these methods do not require any prior estimates of parameter values. Estimated adsorption and desorption rate constants of both slow- and fast-sinking particles were found to increase with depth, while aggregation and disaggregation rate constants were found to decrease with depth. Process contribution results showed that radioactive decay loss of slow-sinking particulate 234Th was compensated by continuous adsorption of dissolved thorium, resulting in that measured flux densities at different depths were approximately the same. Continuous supply from adsorption and aggregation, and negligible radioactive decay loss, explained why 234Th flux densities of fast-sinking particles at deeper depths were higher than those at shallower depths.;In contrast, a widely used mathematical method, the total inverse method, which requires specifying prior estimates of parameter values, was examined by seeding it with different priors to examine the extent to which its results depend on prior information. The results indicate that adsorption, remineralization, and slow-sinking particle desorption rate constants can be relatively well constrained by the total inverse method, but that disaggregation rate constants are highly dependent on prior parameter estimates, suggesting that the latter method should be replaced by the simpler likelihood method.;A conceptual model describing pigment cycling was built. The settling velocity (5 m/d) dividing slow from fast settling particles was much slower than that estimated (98 m/d) using thorium data. Compared with rate constants estimated using thorium, aggregation rate constants estimated using pigment data were lower, and disaggregation rate constants were higher.
机译：本文共分三个部分。所有这些都涉及在海洋中下沉颗粒的行为；所有的数据都来自MedFlux程序。沉没粒子在海洋生物地球化学循环中起着重要作用，因为它们处于负责将光合作用的有机物和能量输送到深海的“生物泵”的核心位置。一方面，这种运输为底栖生物提供了燃料。另一方面，它降低了地表水中的二氧化碳分压，并促进了大气中二氧化碳的吸收。颗粒沉降速度，该速度控制颗粒在水柱中的停留时间以及生物泵的效率。粒子的聚集和分解会影响粒子的沉降速度，因为根据斯托克斯定律，大粒子的沉降速度比小粒子快。;在MedFlux程序中使用缩进旋转球沉降速度（IRS-SV）沉积物收集器收集的T数据使用两种分析方法对比模型。在这两种情况下，使用最大似然估计将这些陷阱收集的11个沉降速度类别最佳地分为两个沉降速度类别（“慢”与“快”）。在第一个分析中，使用似然法估算了粒子的聚集，解聚，再矿化，or的吸附和解吸速率常数。这些方法不需要任何预先估计的参数值。发现慢沉和快沉颗粒的估计吸附和解吸速率常数随深度增加，而聚集和解聚速率常数随深度减小。过程贡献结果表明，慢速沉沉的颗粒234Th的放射性衰变损耗可通过连续吸附溶解的or来补偿，从而导致在不同深度处测得的通量密度大致相同。吸附和聚集的持续供应以及放射性衰变损失可忽略不计，这解释了为什么较快深度的快沉颗粒的234Th通量密度要比较浅深度的要高。相反，广泛使用的数学方法是总逆方法，要求指定参数值的先验估计值，并通过将其与不同先验值一起植入进行检验，以检查其结果在多大程度上取决于先验信息。结果表明，总逆方法可以相对较好地约束吸附，再矿化和下沉颗粒的解吸速率常数，但分解速率常数高度依赖于先前的参数估计值，这表明后一种方法应替换为简单的似然法。;建立了描述颜料循环的概念模型。将沉降速度（5 m / d）从快速沉降颗粒中除以慢速要比使用th数据估算的沉降速度（98 m / d）要慢得多。与使用or估算的速率常数相比，使用颜料数据估算的聚集速率常数较低，而分解速率常数较高。

著录项

  • 作者

    Wang, Weilei.;

  • 作者单位

    State University of New York at Stony Brook.;

  • 授予单位 State University of New York at Stony Brook.;
  • 学科 Biogeochemistry.;Environmental science.;Chemical oceanography.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 150 p.
  • 总页数 150
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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