(a) Linear model (original data) for field versus with least-squares minimisation and 95% CI (narrow band) and 95% PI (broad band). Note the degree of variation possible at different pH levels (cf. Figure 3, Steinhardt and Mengel [13]) |

(b) Linear model (original data) for field versus with Pearson minimisation and 95% CI (narrow band) and 95% PI (broad band) |

Figure 4 |