How does pH change with depth?
Ocean pH changes with depth, but the effect differs from ocean to ocean.
In the North Atlantic, the pH decreases rapidly in the first 500 m and then stays roughly constant as the depth increases.
In the North Pacific, the pH decreases even more rapidly in the first 500 m, but then it increases gradually as the depth increases.
The effect in the first 500 m appears to be correlated with the concentration of dissolved carbon dioxide.
I've found this information:
Ocean acidification varies with depth and time, depends on ocean circulation and microbe activity as well as on ocean chemistry. So say researchers of Montana State University and the University of Hawaii who have studied 20 years of data taken as part of the Hawaii Ocean Time-series (HOT) Program at Station ALOHA, 115 km north of the island of Oahu.