δ 18 O as a tracer of PO 4 3- losses from agricultural landscapes.

Autor: Wells NS; Centre for Coastal Biogeochemistry, School of Environment, Science & Engineering, Southern Cross University, PO Box 157, East Lismore, 2480, NSW, Australia; Department of Soil & Physical Sciences, Faculty of Agricultural & Life Sciences, Lincoln University, Lincoln, 7647, New Zealand. Electronic address: naomi.wells@lincoln.ac.nz., Gooddy DC; British Geological Survey, Wallingford, Oxfordshire, OX10 8BB, UK., Reshid MY; Centre for Coastal Biogeochemistry, School of Environment, Science & Engineering, Southern Cross University, PO Box 157, East Lismore, 2480, NSW, Australia., Williams PJ; British Geological Survey, Wallingford, Oxfordshire, OX10 8BB, UK., Smith AC; British Geological Survey, Keyworth, Nottinghamshire, NG12 5GG, UK., Eyre BD; Centre for Coastal Biogeochemistry, School of Environment, Science & Engineering, Southern Cross University, PO Box 157, East Lismore, 2480, NSW, Australia.
Jazyk: angličtina
Zdroj: Journal of environmental management [J Environ Manage] 2022 Sep 01; Vol. 317, pp. 115299. Date of Electronic Publication: 2022 May 25.
DOI: 10.1016/j.jenvman.2022.115299
Abstrakt: Accurately tracing the sources and fate of excess PO 4 3- in waterways is necessary for sustainable catchment management. The natural abundance isotopic composition of O in PO 4 3- (δ 18 O P ) is a promising tracer of point source pollution, but its ability to track diffuse agricultural pollution is unclear. We tested the hypothesis that δ 18 O P could distinguish between agricultural PO 4 3- sources by measuring the integrated δ 18 O P composition and P speciation of contrasting inorganic fertilisers (compound vs rock) and soil textures (sand, loam, clay) in southwestern Australia. δ 18 O P composition differed between the three soil textures sampled across six livestock farms: sandy soils had lower overall δ 18 O P values (21 ± 1‰) than the loams (23 ± 1‰), which corresponded with a smaller, but more readily leachable, PO 4 3- pool. Fertilisers had greater δ 18 O P variability (∼8‰), with fluctuations due to type and manufacturing year. Consequently, catchment 'agricultural soil leaching' δ 18 O P 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 δ 18 O P to untangle soil-fertiliser P dynamics under controlled conditions, but that its use to trace catchment-scale agricultural PO 4 3- losses is limited by uncertainties in soil biological P cycling and its associated isotopic fractionation.
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Databáze: MEDLINE
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