Whiting events - the episodic precipitation of fine-grained CaCO₃ minerals suspended in the water column - have been documented across a variety of environments, including both marine and lacustrine settings. Whitings could be a predominant source of carbonate muds, especially in the Precambrian, before the rise of green algae, a major source in the Phanerozoic, and are important archives for geochemical proxies of Earth history. While several biological hypotheses have been proposed to explain the onset of these precipitations, no consensus has been reached so far, and it is still unclear which process dominates in which environments. Our understanding of these mechanisms is however crucial to our understanding of the geological record.

Source : American Geophysical Union Fall Meeting 2018.

As described above, Whiting Events are a natural phenomenon in which large suspended clouds of fine-grained chalky material (typically calcium carbonate) appears in marine or fresh water bodies, usually during summer months. There are several theories offering explanations for the events. It's thought there may be a variety of causes.

Some debate exists surrounding the exact cause of whiting events. And although much research exists on the subject, there is still no definitive consensus on the chemical mechanisms behind it. The three most common suggested causes for the phenomenon are: microbiological processes, re-suspension of marine or bottom sediments, and spontaneous direct precipitation from water.

Source : Wikipedia