The image presents four graphs, each depicting a different model of calcium carbonate (CaCO3) dissolution. The top graph shows the autocorrelation of the variance, the middle graph depicts the fraction of test with p < 0.05 is 0.83, the bottom graph shows the fraction of test with p < 0.05 is 0.84, and the right graph shows the fraction of test with p < 0.05 is 0.83.