highly significantp < 0.0001
We found highly significant positive correlations ( r > 0.91, p < 0.0001, n = 324) between the fragment intensities of all samples and only very minor and non-significant deviations from a slope of one, with Δsl ranging from 0.008 (NADW/EMW) to up to 0.243 (Lake/AABW) (Fig. 2 ).