Long term simulations of macronutrients (C, N and P) in UK freshwaters

A - Papers appearing in refereed journals

Bell, V. A., Naden, P. S., Tipping, E., Davies, H. N., Carnell, E., Davies, J. A. C., Dore, A. J., Dragosits, U., Lapworth, D. J., Muhammed, S. E., Quninton, J. N., Stuart, M., Tomilinson, S., Wang, L., Whitmore, A. P. and Wu, L. 2021. Long term simulations of macronutrients (C, N and P) in UK freshwaters. Science of the Total Environment. 776, p. 145813. https://doi.org/10.1016/j.scitotenv.2021.145813

AuthorsBell, V. A., Naden, P. S., Tipping, E., Davies, H. N., Carnell, E., Davies, J. A. C., Dore, A. J., Dragosits, U., Lapworth, D. J., Muhammed, S. E., Quninton, J. N., Stuart, M., Tomilinson, S., Wang, L., Whitmore, A. P. and Wu, L.
Abstract

Over the last two centuries, the landscape of many industrialised nations has been transformed by the spread and
intensification of agriculture, by atmospheric pollution, by human waste (rising in line with population growth), and now by changes in the climate. The research presented here aims to understand and quantify how these long-term changes have impacted UK freshwaters and the flux of macronutrients to the sea. The Long Term Large Scale (LTLS) Freshwater Model presented here used readily-available driving data (climate, land-use, nutrient inputs, catchment topography) to understand and quantify how changes in the UK's macronutrient histories have impacted on freshwater stores and fluxes. Model-reconstructed sources and fluxes of carbon, nitrogen
and phosphorus (C, N and P) from 1800 to 2010 indicate that the rapid increase in the use of agricultural fertilisers after the second world war, and the rising human population, led to a rapid rise in N & P fluxes to rivers. During this period, the modelling shows that the dominant source of N in rivers changed from improved grassland to arable, the dissolved N export to rivers quadrupled, and P from human waste increased by ~600%, despite waste water treatment. The simulations also indicate a net storage of nitrates in groundwater between the 1940s and 1990s, and a net release to coastal waters post-1990; but groundwater retention and later release of C&P are less significant. Overall, modelling indicates that >75% of C, N and P entering freshwaters goes directly to the coastal waters, with 15–20% of C & N removed in river processes. These results constitute the Over the last two centuries, the landscape of many industrialised nations has been transformed by the spread and intensification of agriculture, by atmospheric pollution, by human waste (rising in line with population growth),
and now by changes in the climate. The research presented here aims to understand and quantify how these long-term changes have impacted UK freshwaters and the flux of macronutrients to the sea. The Long Term Large Scale (LTLS) Freshwater Model presented here used readily-available driving data (climate, land-use, nutrient inputs, catchment topography) to understand and quantify how changes in the UK's macronutrient histories have impacted on freshwater stores and fluxes. Model-reconstructed sources and fluxes of carbon, nitrogen and phosphorus (C, N and P) from 1800 to 2010 indicate that the rapid increase in the use of agricultural fertilisers after the second world war, and the rising human population, led to a rapid rise in N & P fluxes to rivers. During this period, the modelling shows that the dominant source of N in rivers changed from improved grassland to arable, the dissolved N export to rivers quadrupled, and P from human waste increased by ~600%, despite waste water treatment. The simulations also indicate a net storage of nitrates in groundwater between the 1940s
and 1990s, and a net release to coastal waters post-1990; but groundwater retention and later release of C&P are less significant. Overall, modelling indicates that >75% of C, N and P entering freshwaters goes directly to the coastal waters, with 15–20% of C & N removed in river processes. These results constitute the first process-based integrated modelling assessment of freshwater macronutrient change at a national scale. The LTLS approach provides a methodology to develop fully-coupled global models of terrestrial, freshwater, atmospheric and marine processes that can take account of changes in land-management and climate.

KeywordsHydrological modelling; Macronutrients; Water quality
Year of Publication2021
JournalScience of the Total Environment
Journal citation776, p. 145813
Digital Object Identifier (DOI)https://doi.org/10.1016/j.scitotenv.2021.145813
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeS2N - Soil to Nutrition [ISPG]
Publisher's version
Output statusPublished
Publication dates
Online19 Feb 2021
Publication process dates
Accepted07 Feb 2021
PublisherElsevier Science Bv
ISSN0048-9697

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