A critical review of mass balance methods for calculating critical loads of nitrogen for forested ecosystems

1993 ◽  
Vol 1 (2) ◽  
pp. 145-156 ◽  
Author(s):  
L. H. Pardo ◽  
C. T. Driscoll
Keyword(s):  
Steady State ◽  
Atmospheric Deposition ◽  
Water Chemistry ◽  
Critical Load ◽  
Mass Balance ◽  
Critical Loads ◽  
Balance Method ◽  
Mass Balance Method ◽  
Basic Cation ◽  
State Water

Critical loads are used in the assessment of air pollution and regulation of the causative emissions to prevent or mitigate ecological damage. We critically review four mass balance methods for calculating critical loads for nitrogen deposition: the steady-state water chemistry method, the nitrogen mass balance method, the basic cation mass balance method, and the steady-state mass balance method. The critical loads may be calculated with respect to effects of acidification associated with nitrate leaching or effects of elevated nitrogen such as eutrophication, excess nitrate loss, and nutrient imbalances. The most useful method for calculating the critical load for nitrogen with respect to effects of elevated atmospheric deposition of nitrogen is the nitrogen mass balance method. The steady-state water chemistry method can be readily applied for regional-scale calculations because it requires only water chemistry data from synoptic surveys of surface waters and does not explicitly consider biogeochemical processes. Both of the other approaches are severely limited by lack of quantitative information on rates of mineral weathering. If weathering data were available, the steady-state mass balance method could be more effectively used to assess critical loads with respect to acidification. Similarly, the basic cation mass balance method could be used to calculate critical loads for both acidity and elevated nitrogen effects. Because of the complexity of the nitrogen cycle, it is not possible to obtain a single critical load for the whole ecosystem. Rather, one should analyze and synthesize several values of critical loads that reflect different components of the ecosystem and different ecological effects of elevated nitrogen deposition (e.g., acidification and eutrophication effects).Key words: atmospheric deposition of nitrogen, acidification, critical loads, nitrogen cycling.

Critical loads of acidity for surface waters in south-central Ontario, Canada: regional application of the Steady-State Water Chemistry (SSWC) model

2002 ◽  
Vol 59 (8) ◽  
pp. 1287-1295 ◽  
Author(s):  
A Henriksen ◽  
P J Dillon ◽  
J Aherne
Keyword(s):  
Steady State ◽  
Water Chemistry ◽  
Critical Load ◽  
Critical Loads ◽  
Lake Chemistry ◽  
Sulphur Deposition ◽  
South Central ◽  
State Water ◽  
Critical Loads Of Acidity ◽  
Sswc Model

Critical loads of acidity and the amount by which these critical loads are exceeded by atmospheric deposition (termed "exceedances") were estimated for 1469 lakes from five regions in south-central Ontario, Canada, using single lake chemistry measurements and sulphur deposition data for the period 1976–1999. Based on the Steady-State Water Chemistry (SSWC) model, four of the five regions had low critical loads, which is consistent with the underlying geology (silicate bedrock) and the thin glacial soils in these regions. Sulphur deposition in the study area showed a clear downward trend over the time period, with a decrease of approximately 50% to current levels of approximately 44 meq·m–2·year–1. As a result of the declining deposition, the portion of lakes with critical load exceedances has dropped substantially, from 74–82% in the four sensitive regions in 1976 to 11–26% in 1999. The pentile critical load is typically used as a regional target to account for uncertainties, but also to ensure that a sufficient percentage of lakes are protected (95%). This suggests that further reductions in emissions are required to reduce depositions to approximately 34 meq·m–2·year–1 (11 kg S·ha–1·year–1) to prevent critical load exceedance.

scholarly journals Long-term modelling of nitrogen turnover and critical loads in a forested catchment using the INCA model

2002 ◽  
Vol 6 (3) ◽  
pp. 395-402 ◽  
Author(s):  
J.-J. Langusch ◽  
E. Matzner
Keyword(s):  
Steady State ◽  
Critical Load ◽  
Mass Balance ◽  
Critical Loads ◽  
Forest Ecosystems ◽  
N Deposition ◽  
N Saturation ◽  
Negative Consequences ◽  
Hydrological Conditions

Abstract. Many forest ecosystems in Central Europe have reached the status of N saturation due to chronically high N deposition. In consequence, the NO3 leaching into ground- and surface waters is often substantial. Critical loads have been defined to abate the negative consequences of the NO3 leaching such as soil acidification and nutrient losses. The steady state mass balance method is normally used to calculate critical loads for N deposition in forest ecosystems. However, the steady state mass balance approach is limited because it does not take into account hydrology and the time until the steady state is reached. The aim of this study was to test the suitability of another approach: the dynamic model INCA (Integrated Nitrogen Model for European Catchments). Long-term effects of changing N deposition and critical loads for N were simulated using INCA for the Lehstenbach spruce catchment (Fichtelgebirge, NE Bavaria, Germany) under different hydrological conditions. Long-term scenarios of either increasing or decreasing N deposition indicated that, in this catchment, the response of nitrate concentrations in runoff to changing N deposition is buffered by a large groundwater reservoir. The critical load simulated by the INCA model with respect to a nitrate concentration of 0.4 mg N l–1 as threshold value in runoff was 9.7 kg N ha–1yr–1 compared to 10 kg ha–1yr–1 for the steady state model. Under conditions of lower precipitation (520 mm) the resulting critical load was 7.7 kg N ha–1yr–1 , suggesting the necessity to account for different hydrological conditions when calculating critical loads. The INCA model seems to be suitable to calculate critical loads for N in forested catchments under varying hydrological conditions e.g. as a consequence of climate change. Keywords: forest ecosystem, N saturation, critical load, modelling, long-term scenario, nitrate leaching, critical loads reduction, INCA

Carbon and nitrogen budgets of a winter rapeseed field in Estonia: a methodology for the quantification of all relevant pools and fluxes

2021 ◽  
Author(s):  
Jordi Escuer-Gatius ◽  
Krista Lõhmus ◽  
Merrit Shanskiy ◽  
Karin Kauer ◽  
Hanna Vahter ◽  
...  
Keyword(s):  
Mass Balance ◽  
Environmental Parameters ◽  
Balance Method ◽  
Nitrogen Budgets ◽  
N Cycle ◽  
Carbon And Nitrogen ◽  
Mass Balance Method ◽  
C Cycle ◽  
Winter Rapeseed ◽  
C And N

<p>Agricultural activities can have several adverse impacts on the environment; such as important greenhouse gas (GHG) emissions. To implement effective mitigation measures and create effective policies, it is necessary to know the full carbon and nitrogen budgets of agro-ecosystems. However, very often, information regarding the pools or fluxes involved in the carbon and nitrogen cycles is limited, and essential complementary data needed for a proper interpretation is lacking.</p><p>This study aimed to quantify all the relevant pools and fluxes of a winter rapeseed, a widely spread crop in the Europe and Baltic regions. The N<sub>2</sub>O and CH<sub>4</sub> fluxes were measured weekly using the closed static chamber method from August 2016 to August 2017 in a winter rapeseed field in Central Estonia. Additionally, nutrient leaching and soil chemical parameters, as well as environmental parameters like soil moisture, electrical conductivity and temperature were monitored. At the end of the season, the rapeseed and weed biomasses were collected, weighed and analyzed. The remaining relevant fluxes in the N cycle were calculated using various non-empirical methods: NH<sub>3</sub> volatilization was estimated from slurry and environmental parameters, N deposition and NO<sub>x</sub> emissions were obtained from national reports, and N<sub>2</sub> emissions were calculated with the mass balance method. Regarding the C cycle, gross primary production (GPP) of the rapeseed field was also calculated by the mass balance method. Simultaneously, for comparison and validation purposes, GPP was estimated from the data provided by MOD17A2H v006 series from NASA, and N<sub>2</sub> was estimated from the measured emissions of N<sub>2</sub>O using the N<sub>2</sub>:N<sub>2</sub>O ratio calculated from the DAYCENT model equations.</p><p>N<sub>2</sub> emissions and GPP were the biggest fluxes in the N and C cycles, respectively. N<sub>2</sub> emissions were followed by N extracted with plant biomass in the N cycle, while in the carbon cycle soil and plant respiration and NPP were the highest fluxes after GPP. The carbon balance was positive at the soil level, with a net increase in soil carbon during the period, mainly due to GPP carbon capture. Contrarily, the nitrogen balance resulted in a net loss of N due to the losses related to gaseous emissions (N<sub>2</sub> and N<sub>2</sub>O) and leaching.</p><p>To conclude, it was possible to close the C and N budgets, despite the inherent difficulties of estimating the different C and N environmental pools and fluxes, and the uncertainties deriving from some of the fluxes estimations.</p>

scholarly journals Critical loads of sulphur and nitrogen for freshwaters in Great Britain and assessment of deposition reduction requirements with the First-order Acidity Balance (FAB) model

2000 ◽  
Vol 4 (1) ◽  
pp. 125-140 ◽  
Author(s):  
C. Curtis ◽  
T. Allott ◽  
J. Hall ◽  
R. Harriman ◽  
R. Helliwell ◽  
...  
Keyword(s):  
Great Britain ◽  
Water Chemistry ◽  
Critical Load ◽  
Acid Deposition ◽  
Critical Loads ◽  
Freshwater Ecosystems ◽  
Acid Neutralizing Capacity ◽  
First Order ◽  
Fab Model ◽  
S Deposition

Abstract. The critical loads approach is widely used within Europe to assess the impacts of acid deposition on terrestrial and freshwater ecosystems. Recent work in Great Britain has focused on the national application of the First-order Acidity Balance (FAB) model to a freshwaters dataset of 1470 lake and stream water chemistry samples from sites across Britain which were selected to represent the most sensitive water bodies in their corresponding 10 km grid square. A ``Critical Load Function" generated for each site is compared with the deposition load of S and N at the time of water chemistry sampling. The model predicts that when catchment processes reach steady-state with these deposition levels, increases in nitrate leaching will depress acid neutralizing capacity (ANC) below the critical threshold of 0 μeql-1 at more than a quarter of the sites sampled, i.e. the critical load of acid deposition is exceeded at these sites. The critical load exceedances are generally found in upland regions of high deposition where acidification has been previously recognised, but critical loads in large areas of western Scotland are also exceeded where little biological evidence of acidification has yet been found. There is a regional variation in the deposition reduction requirements for protection of the sampled sites. The FAB model indicates that in Scotland, most of the sampled sites could be protected by sufficiently large reductions in S deposition alone. In the English and Welsh uplands, both S and N deposition must be reduced to protect the sites. Current international commitments to reduce S deposition throughout Europe will therefore be insufficient to protect the most sensitive freshwaters in England and Wales. Keywords: critical loads; acidification; nitrate; FAB model; acid deposition

scholarly journals A simplified implementation of the stationary liquid mass balance method for on-line OUR monitoring in animal cell cultures

2018 ◽  
Vol 93 (6) ◽  
pp. 1757-1766 ◽  
Author(s):  
Andreu Fontova ◽  
Martí Lecina ◽  
Jonatan López-Repullo ◽  
Iván Martínez-Monge ◽  
Pere Comas ◽  
...  
Keyword(s):  
Mass Balance ◽  
Cell Cultures ◽  
Animal Cell ◽  
Balance Method ◽  
Mass Balance Method ◽  
Liquid Mass ◽  
Stationary Liquid ◽  
Animal Cell Cultures ◽  
On Line

Determination of the volatilization of ammonia from surface-applied cattle slurry by the micrometeorological mass balance method

1987 ◽  
Vol 109 (1) ◽  
pp. 205-207 ◽  
Author(s):  
R. J. Stevens ◽  
H. J. Logan
Keyword(s):  
Mass Balance ◽  
Field Trials ◽  
Balance Method ◽  
Cattle Slurry ◽  
Ammonia Loss ◽  
Mass Balance Method ◽  
Direct Measurements ◽  
Balance Technique ◽  
Land Surfaces ◽  
Grass Growth

Agronomic experiments have shown that nitrogen applied in organic manures gives variable responses in grass growth (van Dijk & Sturm, 1983; Smith, Unwin & Williams, 1985). In a series of field trials in southern England, the average apparent recovery in herbage of the nitrogen from cow slurry was only 13% (Unwin, Pain & Whinham, 1986). The volatilization of ammonia from spread slurry is one possible mechanism for the nitrogen inefficiency (Freney, Simpson & Denmead, 1983; Ryden, 1984). Direct measurements of ammonia loss from land surfaces can be made by micrometeorological methods (Denmead, 1983) and, using the micrometeorological mass balance technique, high rates of ammonia loss were recorded after the land spreading of liquid dairy cattle manure in Canada (Beauchamp, Kidd & Thurtell, 1982). The micrometeorological mass balance method has been used in England to measure ammonia loss from a grazed sward (Ryden & McNeill, 1984). This paper presents the results of an experiment where the same method was used to measure the ammonia loss after land-spreading cattle slurry in Northern Ireland.

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