Causes and effects of composition changes in the ocean

物理海洋学家认为“盐度”是一种含盐量的度量（理论上由浓度大于0.001 g/kg的所有海水成分组成）是保守的——也就是说，只有平流输送、混合以及通过蒸发、降水和河流流入在边界处添加/去除纯水才能改变盐度。然而，这些主要成分并不是完全保守的，它们在海洋中经历了各种各样的过程，导致海盐的相对化学成分发生了微小的变化。化学海洋学家很清楚许多这些主要成分的非保守性，但是，尽管对海水中几乎每一种元素的认识在过去50年中急剧增加，但自20世纪60年代以来，对许多非保守性主要成分相对数量的时空变化的研究几乎完全被忽视了。因此，存在知识鸿沟。***因此，科学地研究这种被忽视的成分变化以及引起这些变化的物理/化学机制，可能被证明是全球海洋环流研究的一个令人兴奋的基本兴趣领域。这是因为这种机制将具有可追踪的结果，可以帮助海洋学家确定海洋中的关键运输途径（类似于有机物再矿化引起的碳/营养变化跟踪全球热盐输送的方式）。此外，这些变化的知识也将改进输运的直接计算，因为更准确的密度场知识将成为可能。新的TEOS-10海水标准的开发突出了这样一个事实，即实际盐度估计的误差，以及由于忽略这些非保守变化而产生的密度等衍生参数的误差，比我们目前“测量”盐度的精度大一到两个数量级。当应用于气候科学问题时，这是我们当前海洋学盐度定义的两个主要问题之一（另一个与定义的计量方面有关）。*****因此，这项拟议工作的目标是更好地定量了解海洋主要组成成分的变化，主要是通过联合电导/密度采样测量不同地区所谓的“盐度异常”，并详细研究可能导致这些异常的一些机制，重点关注双扩散和多扩散过程，这在北极等地区可能很重要**************

Physical oceanographers consider "salinity", a measure of salt content (notionally composed of all seawater constituents with concentrations greater than about 0.001 g/kg), to be conservative - that is, modified only by advective transport, by mixing, and by the addition/removal of pure water at boundaries through evaporation, precipitation, and river inflows. However, these major constituents are not completely conservative, and they undergo a variety of processes in the ocean that result in small changes to the relative chemical composition of sea salt. Chemical oceanographers are well aware of the non-conservative nature of many of these major constituents, but although knowledge about virtually every element in seawater has increased dramatically over the past 50 years, studies of the spatial and temporal variations in the relative amounts of many non-conservative major constituents have been almost completely neglected since the 1960s. Thus, a knowledge gap exists.***Scientifically, studying such neglected composition variations, and the physical/chemical mechanisms that give rise to them, may therefore prove to be an exciting area of fundamental interest to global ocean circulation studies. This is because such mechanisms would have traceable consequences that may help oceanographers identify critical transport pathways in the ocean (analogous to the way in which carbon/nutrient changes from remineralization of organic matter track the global thermohaline conveyor). ***In addition, knowledge of these variations will also improve direct calculations of transport because more accurate knowledge of the density field will be possible. The development of the new TEOS-10 seawater standard has highlighted the fact that the errors in actual salinity estimates, and therefore also in derived parameters like density, which are incurred by ignoring these non-conservative variations, are one to two orders of magnitude larger than the precision with which we currently "measure" salinity. This is one of the two major problems with our current oceanographic definition of salinity when applied to climate science issues (the other is related to metrological aspects of the definition).*****The objectives of this proposed work are therefore to gain a better quantitative understanding of changes in the major constituent composition of the ocean, primarily by measuring the so-called "salinity anomaly" in different regions through combined conductance/density sampling, and to investigate in detail some of the mechanisms that may give rise to these anomalies, concentrating on double- and multi-diffusive processes that may be important in regions like the Arctic.**************