Land‐use dominates climate controls on nitrogen and phosphorus export from managed and natural Nordic headwater catchments

Wit, Heleen de; Lepistö, Ahti; Marttila, Hannu; Wenng, Hannah; Bechmann, Marianne; Blicher-Mathiesen, Gitte; Eklöf, Karin; Bishop, Kevin; Kortelainen, Pirkko; Kronvang, Brian; Kyllmar, Katarina; Raković, Jelena

doi:10.1002/hyp.13939

Cited by 23 publications

(9 citation statements)

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“…Recent evidence suggests that in addition to atmospheric S and N deposition, climate and land use change are becoming increasingly important drivers of changes in boreal lake chemistry: lake browning (De Wit et al., 2016) and nutrient concentrations (N, phosphorus (P)) appear to be controlled by air pollution, land use, and climate (De Wit et al., 2020; Fölster et al., 2014; Vuorenmaa et al., 2018). Afforestation and increased terrestrial productivity have been suggested as a driver of browning in an 80‐year record of DOC (Skerlep et al., 2020).…”

Section: Introductionmentioning

confidence: 99%

Changing Water Chemistry in One Thousand Norwegian Lakes During Three Decades of Cleaner Air and Climate Change

Wit

Garmo

Jackson-Blake

et al. 2023

Global Biogeochemical Cycles

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We present long‐term changes in Norwegian lake water quality across regional gradients in atmospheric pollution, air temperature, hydrology, and vegetation using (a) a national representative lake survey carried out in 1995 and 2019 (ThousandLakes), and (b) an annual lake survey from acid‐sensitive catchments (78 lakes, TrendLakes) from 1990 to 2020. Our analysis encompasses all major chemical constituents, for example, anions and cations, dissolved organic matter (DOM), nutrients, iron (Fe), and silicate (SiO2). During these decades, environmental changes included declines in sulfur (S) and nitrogen (N) deposition, climate warming, and increase in forest biomass. Strong chemical recovery from acidification is found, attributed to large reductions in atmospheric deposition, moderated by catchment processing from land use and climate change. Browning counteracted chemical recovery in some regions, while Ca increased unexpectedly. We suggest that increased weathering, from enhanced terrestrial productivity, is an important driver of increased Ca—substantiated by widespread, substantial increases in SiO2. Light‐ and nutrient‐limitation has become more prevalent, indicated by higher DOM, lower nitrate (NO3), and lower NO3to total phosphorous ratios. Declines in lake NO3 occurred independently of N deposition, suggesting increased catchment N retention, possibly from increased terrestrial productivity. We conclude that decreased air pollution continues to be a dominant driver of long‐term trends in lake chemistry, but climate‐induced increase in terrestrial weathering processes, governed by increased biomass, is likely to have an increasing impact on future lake acidity, nutrient, and light status, that may cascade along the aquatic continuum from rivers to the coast.

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Section: Introductionmentioning

confidence: 99%

Changing Water Chemistry in One Thousand Norwegian Lakes During Three Decades of Cleaner Air and Climate Change

Wit

Garmo

Jackson-Blake

et al. 2023

Global Biogeochemical Cycles

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“…Nutrient loading to headwater streams is influenced by land cover in the surrounding catchments, as shown by studies in North America (Bosch et al, 2020; Coote et al, 1982; Dodds & Oakes, 2006), Europe and Scandinavia (Aguilera et al, 2012; de Wit et al, 2020). Previous studies of nutrient loading to headwater streams in agriculture‐dominated catchments have examined the influence of various agricultural practices and soil types.…”

Section: Introductionmentioning

confidence: 96%

Influence of wetlands on nutrients in headwaters of agricultural catchments

Stempvoort

MacKay

Collins

et al. 2023

Hydrological Processes

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We investigated the influence of land cover on nutrient concentrations (295 samples) in headwater streams over a 2-year period in 10 agriculture-dominated subcatchments (163-8373 ha) in southern Ontario Canada. In this region, monitoring and research on nutrient dynamics in headwater wetlands is sparse. Our results indicated a significant positive correlation (Pearson coefficient ρ = 0.320) between soluble reactive phosphorus (SRP) in the headwater streams and the percentage of wetlands in these agriculture-dominated catchments. This result suggests that headwater wetlands, and other wet riparian zones, are key sources of SRP in the headwater streams.Nitrate concentrations were positively correlated with % agricultural land cover (ρ = 0.316), consistent with previous studies, while SRP concentrations were negatively correlated with % agricultural land cover (ρ = À0.325). There was a significant positive correlation between SRP concentrations and discharge in some of the streams. Seasonal SRP trends appear to be closely related to temperature-dependent seasonal changes in redox conditions, including levels of dissolved O 2 . Surficial geology had some influence on nitrate concentrations in the streams, which tended to be higher in catchments dominated by glacial till (till terrain), compared to catchments with extensive areas of outwash sand, in addition to till terrain.

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“…Reduced supply from the catchment can be related to lower external inputs or greater terrestrial retention. At local (catchment) scales, oligotrophication can be connected to reductions in nutrient supply through, e.g., changes in land use 15 , control of point sources 2,5 , changes in internal cycling 3 and increased retention in upstream water bodies 8 . At regional scales, candidate drivers of oligotrophication include climate change, surface water browning and recovery from acidi cation.…”

Section: Introductionmentioning

confidence: 99%

Widespread and persistent oligotrophication of northern rivers

Futter,

Nilsson,

Camiolo

et al. 2024

Preprint

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Phosphorus (P) is often a limiting nutrient in freshwaters1 and oligotrophication (declining nutrient concentrations), associated with reductions in anthropogenic loading, has occurred in many locations2,3,4,5. Here, we report on persistent and widespread oligotrophication of northern rivers (56o-66o N) that is apparently unrelated to declining anthropogenic loading. Over the past forty years, P concentrations in rivers draining minimally disturbed subarctic, boreal and nemoboreal Swedish catchments have declined by close to 50%, with more rapid declines in already nutrient poor locations. Trends are negatively related to increasing air temperature, pH and alkalinity and unrelated to calcium and organic carbon concentrations and runoff. Trends were strongest in rivers draining catchments with shallow, nutrient poor soils lying above the highest postglacial coastline. Today, P concentrations in most study rivers are below expected background (reference) levels, suggesting we are entering a new water quality regime. These widespread and ongoing P declines are likely to further increase oligotrophication of northern rivers and highlight the need for a new surface water management paradigm addressing the consequences of nutrient scarcity instead of focusing solely on actions targeting nutrient reductions.

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Land‐use dominates climate controls on nitrogen and phosphorus export from managed and natural Nordic headwater catchments

Cited by 23 publications

References 100 publications

Changing Water Chemistry in One Thousand Norwegian Lakes During Three Decades of Cleaner Air and Climate Change

Changing Water Chemistry in One Thousand Norwegian Lakes During Three Decades of Cleaner Air and Climate Change

Influence of wetlands on nutrients in headwaters of agricultural catchments

Widespread and persistent oligotrophication of northern rivers

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