Predicting nitrogen and acidity effects on long-term dynamics of dissolved organic matter

Rowe, Ed; Tipping, Edward; Posch, Maximilian; Oulehle, Filip; Cooper, David M.; Jones, Timothy G. J.; Burden, Annette; Hall, J.; Evans, C. D.

doi:10.1016/j.envpol.2013.08.023

Cited by 35 publications

(33 citation statements)

References 70 publications

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“…Observing differences that occur at different scales and between different processes has added to our knowledge concerning those factors that control DOC dynamics (Clark et al 2010). The development of models based on a mechanistic understanding has also helped to unify our understanding of processes (Futter et al 2007;Rowe et al 2014). In the present study we have shown that even apparently negligible differences in simulating present day conditions can lead to large uncertainties when projecting future catchment [DOC] and exports (Fig.…”

Section: Change In Hydroclimatic Regimesmentioning

confidence: 76%

Cross-scale ensemble projections of dissolved organic carbon dynamics in boreal forest streams

et al. 2014

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Climate is an important driver of dissolved organic carbon (DOC) dynamics in boreal catchments characterized by networks of streams within forest-wetland landscape mosaics. In this paper, we assess how climate change may affect stream DOC concentrations ([DOC]) and export from boreal forest streams with a multi-model ensemble approach. First, we apply an ensemble of regional climate models (RCMs) to project soil temperatures and stream-flows. These data are then used to drive two biogeochemical models of surface water DOC: (1) The Integrated Catchment model for Carbon (INCA-C), a detailed process-based model of DOC operating at the catchment scale, and (2) The Riparian Integration Model (RIM), a simple dynamic hillslope scale model of stream [DOC]. All RCMs project a consistent increase in temperature and precipitation as well as a shift in spring runoff peaks from May to April. However, they present a considerable range of possible future runoff conditions with an ensemble median increase of 31 % between current and future (2061-2090) conditions. Both biogeochemical models perform well in describing the dynamics of presentday stream [DOC] and fluxes, but disagree in their future projections. Here, we assess possible futures in three boreal catchments representative of forest, mire and mixed landscape elements. INCA-C projects a wider range of stream [DOC] due to its temperature sensitivity, whereas RIM gives consistently larger inter-annual variation and a wider range of exports due to its sensitivity to hydrological variations. The uncertainties associated with modeling complex processes that control future DOC dynamics in boreal and temperate catchments are still the main limitation to our understanding of DOC mechanisms under changing climate conditions. Novel, currently overlooked or unknown drivers may appear that will present new challenges to modelling DOC in the future.

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Section: Change In Hydroclimatic Regimesmentioning

confidence: 76%

Cross-scale ensemble projections of dissolved organic carbon dynamics in boreal forest streams

et al. 2014

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“…For example, it has been suggested that net primary productivity (NPP), and hence the supply of potentially soluble organic matter, is now higher than in pre-industrial times as a result of the accumulation of atmospherically deposited reactive nitrogen in these catchments (Rowe et al 2014;Tipping et al 2012). …”

Section: Introductionmentioning

confidence: 99%

Spatial controls on dissolved organic carbon in upland waters inferred from a simple statistical model

et al. 2015

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Because of the implications for drinking water treatment and supply there is increasing interest in the potential for mitigation through local land management, and for forecasting the likely impact of environmental change.However, the dominant controls on DOC production remain unresolved, hindering the establishment of appropriate reference levels for specific locations. Here we demonstrate that spatial variation in long-term average DOC levels draining upland UK catchments is highly predictable using a simple multiple logistic regression model comprising variables representing wetland soil cover, rainfall, altitude, catchment sensitivity to acidification, and current acid deposition. A negative relationship was observed between DOC concentration and altitude that, fro catchments dominated by organo-mineral soils, is plausibly explained by the combined effects of changing net primary production and temperature-dependent decomposition.However, the magnitude of the altitude effect was considerably greater for catchments with a high proportion of wetland cover, suggesting that additional controls influence these sites such as impeded respiratory loss of carbon in wet soils and/or an increased susceptibility to water level drawdown at lower altitudes. The model suggests 1) that continuing reductions in sulphur deposition on acid sensitive organo-mineral soils, will drive further significant increases in DOC and, 2) given the differences in the magnitude of the observed altitude-DOC relationships, that DOC production from catchments with peat-dominated soils may be more sensitive to climate change than those dominated by mineral soils. However, given that mechanisms remain unclear, the latter warrants further investigation.

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“…Some studies have linked the OC rise to recent changes in land-use practices, such as the drainage and burning of peatlands (18,19), or to changes in land cover (20). Other proposed explanations are the increase in atmospheric carbon dioxide levels (21) and the elevated atmospheric deposition of nitrogen (22,23), both of which support increased plant productivity.…”

mentioning

confidence: 99%

Early land use and centennial scale changes in lake-water organic carbon prior to contemporary monitoring

Meyer-Jacob

Tolu

Bigler

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Organic carbon concentrations have increased in surface waters across parts of Europe and North America during the past decades, but the main drivers causing this phenomenon are still debated. A lack of observations beyond the last few decades inhibits a better mechanistic understanding of this process and thus a reliable prediction of future changes. Here we present past lake-water organic carbon trends inferred from sediment records across central Sweden that allow us to assess the observed increase on a centennial to millennial time scale. Our data show the recent increase in lake-water carbon but also that this increase was preceded by a landscape-wide, long-term decrease beginning already A.D. 1450-1600. Geochemical and biological proxies reveal that these dynamics coincided with an intensification of human catchment disturbance that decreased over the past century. Catchment disturbance was driven by the expansion and later cessation of widespread summer forest grazing and farming across central Scandinavia. Our findings demonstrate that early land use strongly affected past organic carbon dynamics and suggest that the influence of historical landscape utilization on contemporary changes in lake-water carbon levels has thus far been underestimated. We propose that past changes in land use are also a strong contributing factor in ongoing organic carbon trends in other regions that underwent similar comprehensive changes due to early cultivation and grazing over centuries to millennia.lake-water quality | carbon cycling | land use | Holocene | paleoecology O ver the past three decades, monitoring programs have recorded a widespread increase of organic carbon (OC) concentrations in surface waters in parts of Europe and North America (1-4). OC in lakes and rivers plays a major role in the global carbon cycle by transporting carbon from terrestrial to freshwater and marine environments (5), determining drinking water quality and associated treatment costs (6), and affecting aquatic ecosystem functioning. In aquatic ecosystems, OC influences energy mobilization, light conditions (7), water acidity (8), as well as the transport of metals and pollutants (9). The widespread occurrence of this increase in surface water OC, also referred to as browning or brownification due to an associated increase in color, suggests that regional rather than local factors are the drivers behind this phenomenon, but at present the underlying mechanisms are still controversial.Several hypotheses have been proposed to explain this recent OC increase, from climate change to changes in anthropogenic forcing such as declining atmospheric acid deposition or alterations in landscape utilization. A number of climate-sensitive mechanisms have been suggested to cause an increase in OC export from the terrestrial to the aquatic environment; for example, increased temperatures enhance decomposition rates in organic-rich soils (10) and promote vegetation cover (11). Changes in the amount and timing of precipitation potentially lead to alteration...

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Predicting nitrogen and acidity effects on long-term dynamics of dissolved organic matter

Cited by 35 publications

References 70 publications

Cross-scale ensemble projections of dissolved organic carbon dynamics in boreal forest streams

Cross-scale ensemble projections of dissolved organic carbon dynamics in boreal forest streams

Spatial controls on dissolved organic carbon in upland waters inferred from a simple statistical model

Early land use and centennial scale changes in lake-water organic carbon prior to contemporary monitoring

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