(a) naive trend (mS m−1 ) (b) ’correct’ trend (mS m−1 ) (c) (mS m−1 ) (d) (mS m−1 ) Figure 21: Meigem electric conductivity: naive trend = OK - SR - LR (Left); manually optimized trend = OK - 2.2SR - 2.3LR (Right) 39