Quantifying the structure of very small (<25 nm) natural aquatic colloids

天然水生胶体被定义为尺寸在1纳米到1微米(10^-9/10^-6米)之间的固相物质，因此非常小，并且被精细分割，具有非常大的表面积。它们普遍存在于水生(和陆地)环境中，由有机(腐殖质和多糖)、无机(金属氧化物)和生物(病毒和细菌)等不同类型的物质组成，这些相以复杂的方式混合在一起。我们知道，胶体在化学和物理上结合了微量污染物，如金属，这些金属如汞、镉、镍等可能是有毒的。此外，我们知道这些胶体影响痕量金属的命运和行为，并控制金属的运输和生物利用度。此外，众所周知，在许多环境条件下，非常小的部分(小于约25 nm)在金属结合中非常重要，并在生物利用度中起着决定性的作用。尽管这些知识主要是定性的，而不是定量的，但在这一领域仍有许多未知之处。特别是，我们对‘纳米胶体’(&lt；ca 25 nm)结构的了解很差，在这里改进我们的知识库对于进一步了解微量元素的化学、运输和生物利用度是必不可少的。该项目旨在通过验证一种将流场-流动分馏(FlFFF)和原子力显微镜(AFM)相结合的方法来量化纳米胶体的形状及其渗透性(对溶质和溶剂分子)来解决其中的一些不确定性。关于这些结构措施的信息可以包含在一个简单的比率中，可用于对物种形成和生物有效性的进一步模拟研究，这对于更好地从根本上理解纳米胶体在微量元素行为中的环境‘功能’至关重要。这一研究领域类似于上个世纪对蛋白质和遗传物质等生物大分子结构-功能关系的研究。

Natural aquatic colloids are defined as solid phase material between the sizes of 1 nm and 1 um (10^-9 / 10^-6 m) in size and are thus extremely small and finely divided with very large surface areas. They are ubiquitous in the aquatic (and terrestrial) environment and composed of different types of material such as organic (humic substances and polysaccharides), inorganic (metal oxides) and biological (viruses and bacteria) and these phases are mixed together in complex ways. We know that colloids chemically and physically bind trace pollutants such as metals and that these metals such as mercury, cadmium, nickel etc., may be toxic. In addition, we know that these colloids affect trace metal fate and behaviour and control metal transport and bioavailability. Further, it is known that the very small fraction (less than approximately 25 nm) is very important in metal binding under many environmental conditions and plays a defining role in bioavailability. Despite this knowledge which is primarily qualitative rather quantitative, there is a great deal that remains unknown in this area. In particular, our knowledge of 'nano-colloidal' (< ca 25 nm) structure is poor and improving our knowledge base here is essential to further understanding trace element chemistry, transport and bioavailability. This project aims to address some of these uncertainties by validating a methodology coupling flow field-flow fractionation (FlFFF) and atomic force microscopy (AFM) to quantify the shape of nanocolloids and their permeability (to solute and solvent molecules). Information about these structural measures can be contained within a simple ratio, usable in further modelling studies on speciation and bioavailability are essential to better fundamental understanding of the environmental 'function' of nanocolloids in trace element behaviour. The area of investigation is analogous to research over the last century into the structure-function relationships of biological macromolecules such as proteins and genetic material.