Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth, UK.
ISME J. 2011 Jan;5(1):1-7. doi: 10.1038/ismej.2010.79. Epub 2010 Jun 10.
The pH of the surface ocean is changing as a result of increases in atmospheric carbon dioxide (CO(2)), and there are concerns about potential impacts of lower pH and associated alterations in seawater carbonate chemistry on the biogeochemical processes in the ocean. However, it is important to place these changes within the context of pH in the present-day ocean, which is not constant; it varies systematically with season, depth and along productivity gradients. Yet this natural variability in pH has rarely been considered in assessments of the effect of ocean acidification on marine microbes. Surface pH can change as a consequence of microbial utilization and production of carbon dioxide, and to a lesser extent other microbially mediated processes such as nitrification. Useful comparisons can be made with microbes in other aquatic environments that readily accommodate very large and rapid pH change. For example, in many freshwater lakes, pH changes that are orders of magnitude greater than those projected for the twenty second century oceans can occur over periods of hours. Marine and freshwater assemblages have always experienced variable pH conditions. Therefore, an appropriate null hypothesis may be, until evidence is obtained to the contrary, that major biogeochemical processes in the oceans other than calcification will not be fundamentally different under future higher CO(2)/lower pH conditions.
由于大气二氧化碳（CO2）的增加，表层海洋的 pH 值正在发生变化，人们担心较低的 pH 值和海水碳酸盐化学变化可能会对海洋生物地球化学过程产生潜在影响。然而，将这些变化置于现今海洋的 pH 值背景下是很重要的，因为现今海洋的 pH 值并非恒定不变，它会随着季节、深度和生产力梯度系统地变化。然而，在评估海洋酸化对海洋微生物的影响时，这种 pH 值的自然变化很少被考虑在内。由于二氧化碳的微生物利用和产生，以及在较小程度上由于硝化等其他微生物介导的过程，表层 pH 值会发生变化。可以与其他水生环境中的微生物进行有用的比较，这些微生物很容易适应非常大且快速的 pH 值变化。例如，在许多淡水湖中，pH 值变化在几个数量级上大于二十世纪海洋中预测的变化，而且这种变化可以在数小时内发生。海洋和淡水生物群一直经历着可变的 pH 值条件。因此，一个合适的零假设可能是，除非有相反的证据，否则在未来高 CO2/低 pH 值条件下，除钙化作用外，海洋中的主要生物地球化学过程不会有根本的不同。
