Factors influencing nitrogen inputs and outputs in two Scottish upland catchments

Edwards, Anthony C.; Creasey, John; Cresser, Malcolm S.

doi:10.1111/j.1475-2743.1985.tb00664.x

Cited by 41 publications

(9 citation statements)

References 25 publications

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“…NO 3 -is often immobilized by microbial and plant uptake during the warmer months, while biological uptake and transformation of NO 3 -is highly reduced during the colder months due to the weaker ability of retaining NO 3 - (Black et al 1993;Edwards et al 1985;Balestrini et al 2013). However, in our data, no similar variation in concentrations was observed during different reasons.…”

Section: Spatial Distributions Of N Fractionscontrasting

confidence: 74%

Dissolved organic nitrogen (DON) in seventeen shallow lakes of Eastern China

et al. 2015

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The terrestrial export of dissolved organic nitrogen (DON) is associated with climate, geography and land use, and thus is influenced by geo-climatic variability, human interference, the farmland and woodland in soil, and hydrological connection levels to rivers. A dataset was presented including two catchments covering the major land use types and different hydrological connection levels to rivers within Eastern China: Middle Yangtze (river-isolated lakes) and Huai River (non-river-connected lakes). Total dissolved nitrogen [TDN, including DON and dissolved inorganic nitrogen (DIN)], total organic carbon (TOC) and physical variables (T, DO, pH, OPR, conductivity) were measured in seventeen lakes over summer and winter. In all study lakes, both DON and NH 4 ? -N were the major fractions of TDN, with much lower proportions of NO 3 --N and NO 2 -N. A variation pattern with higher DON and lower NH 4 ? -N concentrations was observed in non-river-connected lakes, and yet reverse pattern in river-isolated lakes. Higher DON concentrations were recorded with a high extent of farmland in land use, reflecting the influence of human impact on DON loads. These relationships and correlation analysis indicated that DON concentrations were controlled by several factors including temperature, latitude, precipitation, hydrological process and farmland cover in land use. Seasonal variations showed that higher mean surface DON concentration (0.004-0.666 mg/L) was measured in winter, which might be due to resuspension of the organic matter from bottom sediments. The uptake of DON by phytoplankton and bacteria was likely to be the most significant reason for low DON concentrations (0.006-0.335 mg/L) during the summer, supported by increasing DON concentrations accompanied with disappearing Chla after phytoplankton died. Much higher NO 3 --N concentrations in summer were attributed to nitrogenous fertilizer, high rainfall, and inorganic nitrogen suspending brought by frequent wind wave.

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Section: Spatial Distributions Of N Fractionscontrasting

confidence: 74%

Dissolved organic nitrogen (DON) in seventeen shallow lakes of Eastern China

et al. 2015

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“…Such studies have revealed distinct seasonal patterns of DOC and N release, with concentrations of DOC and DON displaying summer maxima and winter minima, and vice versa for NO 3 -N. The patterns for DOC and DON are generally explained by enhanced turnover and release of soluble 623 organic matter in soils (Grieve, 1984) and surface waters (Chapman et al, 2001) respectively during the warmer summer months, whereas the pattern for NO 3 -N reflects the seasonal availability of NO 3 -N in the soil for leaching, which is significantly reduced during the summer by biological uptake (Edwards et al, 1985). However, soil type and drainage status can influence these trends, since DOC may be removed from solution by adsorption in sesquioxide-rich mineral horizons (Jardine et al, 1989;Kennedy et al, 1996), and NO 3 -N may not be produced in waterlogged profiles, due to the effects of anaerobia (Rangely and Knowles, 1988;Adamson et al, 1998).…”

Section: Introductionmentioning

confidence: 91%

Factors influencing the release of dissolved organic carbon and dissolved forms of nitrogen from a small upland headwater during autumn runoff events

Cooper¹,

Thoss²,

Watson³

2006

Hydrological Processes

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Abstract:We identify and assess the relative importance of the principal factors influencing the release of dissolved organic carbon (DOC) and dissolved forms of nitrogen (N) from a small upland headwater dominated by podzolic soils during a sequence of autumn runoff events. We achieve this by subjecting high-resolution hydrometeorological and hydrochemical data to an R-mode principal component factor analysis and a stepwise multivariate regression analysis. We find that the release of DOC and N is influenced by four principal factors, namely event magnitude, soil water flow through the Bs horizon, the length of time since the soil profile was last flushed, and rewetting of the H horizon. The release of DOC and dissolved organic nitrogen (DON) is most strongly influenced by the combination of event magnitude and soil water flow through the Bs horizon, and to a lesser extent by the length of time since the soil profile was last flushed. Rewetting of the H horizon also influences the release of DOC, but this is not the case for DON. The release of nitrate (NO 3 -N) is most strongly influenced by the combination of the length of time since the soil profile was last flushed and rewetting of the H horizon, and to a lesser extent by event magnitude. Soil water flow through the Bs horizon does not influence the release of NO 3 -N. We argue that the mechanisms by which the above factors influence the release of DOC and N are probably strongly associated with moisture-dependent biological activity, which governs the turnover of organic matter in the soil and limits the availability of NO 3 -N in the soil for leaching. We conclude that the release of DOC and N from upland headwaters dominated by podzolic soils is largely controlled by the variable interaction of hydrometeorological factors and moisture-dependent biological processes, and that a shift in climate towards drier summers and wetter winters may result in the release of DOC and N becoming increasingly variable and more episodic in the future.

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“…As a consequence, once deposition exceeds 10-16 kg N ha −1 yr −1 , retention of this N by the vegetation will cease. Although N concentrations in Calluna litter suggest that the litter layer can contribute to N retention, especially of NO − 3 (Edwards et al, 1985), according to Black et al (1993), peats in particular, but also moorlands, are the least likely semi-natural ecosystems to retain N.…”

Section: How Does the Vegetation Respond To N?mentioning

confidence: 99%

Fate of N in a peatland, Whim bog: immobilisation in the vegetation and peat, leakage into pore water and losses as N<sub>2</sub>O depend on the form of N

et al. 2013

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Abstract. Peatlands represent a vast carbon reserve that has accumulated under conditions of low nitrogen availability. Given the strong coupling between the carbon and nitrogen cycles, we need to establish the consequences of the increase in reactive nitrogen deposition for the sustainability of peatlands, and whether the form in which the nitrogen is deposited makes a difference. We have addressed these questions using a globally unique field simulation of reactive N deposition as dry deposited ammonia and wet deposited reduced N, ammonium and oxidised N, nitrate, added as ammonium chloride or sodium nitrate, to an ombrotrophic peatland, Whim bog in SE Scotland. Here we report the fate of 56 kg N ha −1 yr −1 additions over 10 yr and the consequences. The effects of 10 yr of reactive N additions depended on the form in which the N was applied. Ammonia-N deposition caused the keystone Sphagnum species, together with the main shrub Calluna and the pleurocarpous mosses, to disappear, exposing up to 30 % of the peat surface. This led to a significant increase in soil water nitrate and nitrous oxide emissions. By contrast wet deposited N, despite significantly reducing the cover of Sphagnum and Pleurozium moss, did not have a detrimental effect on Calluna cover nor did it significantly change soil water N concentrations or nitrous oxide emissions. Importantly 10 yr of wet deposited N did not bare the peat surface nor significantly disrupt the vegetation enabling the N to be retained within the carbon rich peatland ecosystems. However, given the significant role of Sphagnum in maintaining conditions that retard decomposition, this study suggests that all nitrogen forms will eventually compromise carbon sequestration by peatlands through loss of some keystone Sphagnum species.

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Factors influencing nitrogen inputs and outputs in two Scottish upland catchments

Cited by 41 publications

References 25 publications

Dissolved organic nitrogen (DON) in seventeen shallow lakes of Eastern China

Dissolved organic nitrogen (DON) in seventeen shallow lakes of Eastern China

Factors influencing the release of dissolved organic carbon and dissolved forms of nitrogen from a small upland headwater during autumn runoff events

Fate of N in a peatland, Whim bog: immobilisation in the vegetation and peat, leakage into pore water and losses as N<sub>2</sub>O depend on the form of N

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Factors influencing nitrogen inputs and outputs in two Scottish upland catchments

Cited by 41 publications

References 25 publications

Dissolved organic nitrogen (DON) in seventeen shallow lakes of Eastern China

Dissolved organic nitrogen (DON) in seventeen shallow lakes of Eastern China

Factors influencing the release of dissolved organic carbon and dissolved forms of nitrogen from a small upland headwater during autumn runoff events

Fate of N in a peatland, Whim bog: immobilisation in the vegetation and peat, leakage into pore water and losses as N&lt;sub&gt;2&lt;/sub&gt;O depend on the form of N

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Fate of N in a peatland, Whim bog: immobilisation in the vegetation and peat, leakage into pore water and losses as N<sub>2</sub>O depend on the form of N