An ultra-pure water supply for preparation of artificial seawater medium to culture phytoplankton

浮游植物通过光合作用吸收二氧化碳并将其转移到深海，从而促进全球碳循环。由于低浓度的微量金属降低了二氧化碳吸收的效率，它们的生长在大片地区受到限制。确定浮游植物如何吸收金属以及它们生长所需金属的种类和数量是生物海洋学中的重要问题。人工海水介质的使用极大地促进了浮游植物微量金属营养的研究，因为人工海水介质中微量金属的组成和化学性质已经被了解。人造海水复制了天然海水中主要盐成分的组成，可以在远离海洋的实验室中大量制备。它的营养成分和金属成分是精确已知和可复制的，这使得它比天然海水更适合进行培养研究。制备人造海水的一个基本要求是大量供应不含金属污染物的超纯水。在最广泛使用的人工培养基中，对各种元素的浓度进行严格控制和调节，以研究它们对浮游植物生长的影响。这些知识对于了解浮游植物如何适应和适应海洋表面低浓度的铁和其他微量金属至关重要。还需要大量的超纯水来冲洗和清洁烧瓶和容器，以去除污染的金属，并分析这些元素的细胞浓度。

Phytoplankton contribute to the global carbon cycle through photosynthetic uptake and transfer of carbon dioxide to the deep sea. Their growth is limited in large regions by low concentrations of trace metals that reduce the efficiency of CO2 uptake. Determining how phytoplankton take up metals and what are the types and amounts they require for growth are important questions in Biological Oceanography. Study of the trace metal nutrition of phytoplankton has been greatly facilitated by the use of artificial seawater medium in which the composition and chemistry of the trace metals is known and understood. Artificial seawater replicates the composition of the major salt constituents in natural waters and can be prepared in large quantities at labs located far from sea. Its composition of nutrients and metals is precisely known and replicable, making it better suited than natural seawater for culture studies. An essential requirement for the preparation of artificial seawater is a large supply of ultra-pure water free of metal contaminants. In Aquil, the most widely used artificial medium, the concentrations of the various species of elements are tightly controlled and regulated to study their effect on phytoplankton growth. Such knowledge is essential to understand how phytoplankton acclimate and adapt to low concentrations of iron and other trace metals in the surface ocean. Large quantities of ultra-pure water are also needed for rinsing and cleaning flask and containers to remove contaminating metals and in the analysis of the cellular concentrations of these elements.