You may need to go out of your depth to find the seawater-studying geochemist hidden in this sudoku-inspired puzzle

Solve this wordoku in the same way as a sudoku with letters instead of numbers (each of the nine letters in each row, column and nine-square cell). Once solved, one of the overall diagonals can be rearranged into the name of a geochemist who studied carbon dioxide levels in seawater.

This week’s letters are: A E H I M R S T U