2022 article
Phosphate oxygen isotope ratios in vegetated riparian buffer strip soils
Bauke, S. L., Wang, Y., Saia, S. M., Popp, C., Tamburini, F., Paetzold, S., … Sperber, C. (2022, April 4). VADOSE ZONE JOURNAL.
Abstract The oxygen isotopic composition of phosphate (δ 18 O P ) in soils and surface water bodies has been used to trace terrestrial P inputs into aquatic ecosystems. However, enhanced biological activity in vegetated riparian buffer strips (VBSs) may lead to an alteration of δ 18 O P values. The objective of this study was to assess whether enhanced biological cycling of P in VBS soils can be identified using δ 18 O P values. For this purpose, we sampled temperate grassland soils at various depths along a VBS to grassland transect. Here, we combined sequential P soil extracts with an analysis of δ 18 O P values. Soil P pool concentrations tended to decrease significantly along the transect from the VBS to the grassland soils; the strength of this relationship varied with P extract, sample depth, and inorganic or organic bonding form. For the δ 18 O P values of the 1 M HCl‐extractable P we observed a significant negative trend along the VBS to grassland transect, indicating a tendency for accelerated rates of biological cycling of P within the VBS soil profile compared with the upslope soils. We conclude that oxygen isotope‐based assessments of P source contributions to freshwater bodies should consider the enhanced biological turnover of P in VBS soils.