δ18O as a tracer of PO43− losses from agricultural landscapes

Wells, Naomi S.; Gooddy, Daren C.; Reshid, Mustefa Yasin; Williams, Peter J.; Smith, Andrew C.; Eyre, Bradley D.. 2022 δ18O as a tracer of PO43− losses from agricultural landscapes. Journal of Environmental Management, 317, 115299. 10.1016/j.jenvman.2022.115299

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Official URL: http://dx.doi.org/10.1016/j.jenvman.2022.115299

Abstract/Summary

Accurately tracing the sources and fate of excess PO43− in waterways is necessary for sustainable catchment management. The natural abundance isotopic composition of O in PO43− (δ18OP) is a promising tracer of point source pollution, but its ability to track diffuse agricultural pollution is unclear. We tested the hypothesis that δ18OP could distinguish between agricultural PO43− sources by measuring the integrated δ18OP composition and P speciation of contrasting inorganic fertilisers (compound vs rock) and soil textures (sand, loam, clay) in southwestern Australia. δ18OP composition differed between the three soil textures sampled across six livestock farms: sandy soils had lower overall δ18OP values (21 ± 1‰) than the loams (23 ± 1‰), which corresponded with a smaller, but more readily leachable, PO43− pool. Fertilisers had greater δ18OP variability (∼8‰), with fluctuations due to type and manufacturing year. Consequently, catchment ‘agricultural soil leaching’ δ18OP signatures could span from 18 to 25‰ depending on both fertiliser type and timing (lag between application and leaching). These findings emphasise the potential of δ18OP to untangle soil-fertiliser P dynamics under controlled conditions, but that its use to trace catchment-scale agricultural PO43− losses is limited by uncertainties in soil biological P cycling and its associated isotopic fractionation.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1016/j.jenvman.2022.115299
ISSN:	03014797
Additional Keywords:	GroundwaterBGS, Groundwater
Date made live:	29 Jul 2022 13:30 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/533000

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1016/j.jenvman.2022.115299

ISSN:

03014797

Additional Keywords:

GroundwaterBGS, Groundwater

Date made live:

29 Jul 2022 13:30 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/533000