I never had an opinion on acid rain because I live in limestone country. I do like global warming because I handle heat very well and winter heating a house cost a lot

Acid rain is a problem for the natural environment rather than the citrus grower.

In the 1980's in Northern Europe, fresh-water fish stocks were plummeting and vast areas of forest starting to die. The acidity was caused mainly by burning fossil-fuels in industrialised countries like here in the UK. The prevailing winds carried this pollution particularly towards Scandinavia.

Since then, EU regulations have forced reductions in pollution - at considerable cost - so that acid rain is no longer a major problem and the forests and lakes are recovering.

The UK Government publishes an annual report on acid pollutants. Very technical, but if anyone wishes to read it, UK Eutrophying and Acidifying Atmospheric Pollutant Report

I use 2-2-1 where the center 2 is compost from my compost pile. It is totally composted

I must admit that I have never really considered whether my watering pH is significantly affected my citrus plants. I use stored rainwater for most of the year, with mains water usually only for a few months in summer. However, with the majority of my potted plants standing outside in summer, falling rain often provides all they need. Local supplied mains water is considered to be hard (we use a softener for indoor domestic supplies), so when it is required to some extent this will cancel out any acidity from stored rainwater. I also use limited supplies of aircon drain water when available.

Some people also worry about dissolved oxygen levels. There are companies selling water 'aerators' which claim great benefits for plants.