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

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

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Present and potential nitrogen outputs from Norwegian soft water lakes – an assessment made by applying the steady-state First-order Acidity Balance (FAB) model

Hydrology and Earth System Sciences ◽

10.5194/hess-6-101-2002 ◽

2002 ◽

Vol 6 (1) ◽

pp. 101-112 ◽

Cited By ~ 7

Author(s):

Ø. Kaste ◽

A. Henriksen ◽

M. Posch

Keyword(s):

Steady State ◽

Critical Loads ◽

N Deposition ◽

Soft Water ◽

N Leaching ◽

First Order ◽

Fab Model ◽

The Future ◽

N Immobilisation

Abstract. The steady-state First-order Acidity Balance (FAB) model for calculating critical loads of sulphur (S) and nitrogen (N) is applied to 609 Norwegian soft-water lakes to assess the future nitrate (NO3‾) leaching potential under present (1992-96) S and N deposition. The lakes were separated into five groups receiving increasing levels of N deposition (<25, 25-49, 50-74, 75-99 and 100-125 meq m-2yr-1). Using long-term sustainable N sink rates presently recommended for FAB model applications, N immobilisation, net N uptake in forests, denitrification and in-lake N retention were estimated for each group of lakes. Altogether, the long-term N sinks constituted 9.9 ± 3.2 to 40.5 ± 11.4 meq m-2yr-1 in the lowest and highest N deposition categories, respectively. At most sites, the current N deposition exceeds the amount of N retained by long-term sustainable N sinks plus the NO3‾ loss via the lake outlets. This excess N, which is currently retained within the catchments may, according to the FAB model, leach as acidifying NO3‾ in the future. If these predictions are fulfilled, NO3‾ leaching at sites in the various N deposition categories will increase dramatically from present (1995) mean levels of 1-20 meq m-2yr-1, to mean levels of 7-70 meq m-2yr-1 at future steady state. To illustrate the significance of such an increase in NO3‾ leaching, the mean Acid Neutralising Capacity (ANC) at sites in the highest N deposition category may decrease from -18 ± 15 μeq L-1 at present, to -40 ± 20 μeq L-1. Under present S and N deposition levels, the FAB model predicts that 46% of the Norwegian lakes may experience exceedances of critical loads for acidifying deposition. In comparison, the Steady-State Water Chemistry model (SSWC), which considers only the present N leaching level, estimates critical load exceedances in 37% of the lakes under the same deposition level. Thus far, there are great uncertainties regarding both the time scales and the extent of future N leaching, and it is largely unknown whether the FAB model predictions will ever be fulfilled. Hence, long-term monitoring and further studies on N immobilisation processes under varying N deposition levels and ecosystem types seem necessary to make better predictions of future NO3‾ leaching. Keywords: Lakes, hydrochemistry, nitrogen, nitrate, sinks, leaching, acidification, critical loads, FAB model

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

Environmental Reviews ◽

10.1139/a93-011 ◽

1993 ◽

Vol 1 (2) ◽

pp. 145-156 ◽

Cited By ~ 2

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.

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Soil Nitrogen and Sulfur Leaching in a Subtropical Forest at a Transition State under Decreasing Atmospheric Deposition

Forests ◽

10.3390/f12121798 ◽

2021 ◽

Vol 12 (12) ◽

pp. 1798

Author(s):

Piaopiao Ke ◽

Gaoyue Si ◽

Yao Luo ◽

Zhenglin Cheng ◽

Qian Yu ◽

...

Keyword(s):

Transition State ◽

Soil Layer ◽

N Deposition ◽

Subtropical Forest ◽

N Leaching ◽

N Saturation ◽

Subtropical Forests ◽

Net Flux ◽

Throughfall Deposition

Anthropogenic emissions of nitrogen- (N) and sulfur (S)-containing pollutants have declined across China in recent years. However, the responses of N and S depositions and dynamics in soil remain unclear in subtropical forests. In this study, the wet and throughfall depositions of dissolved inorganic N (DIN) and SO42− were continuously monitored in a mildly polluted subtropical forest in Southeast China in 2017 and 2018. Moreover, these solutes in soil water along the soil profile were monitored in 2018. Throughfall deposition of DIN and S decreased by 59% and 53% in recent 3 years, respectively, which can be majorly attributed to the decreases in wet depositions of NO3− and SO42−. Meanwhile, NH4+ deposition remained relatively stable at this site. Even though N deposition in 2018 was below the N saturation threshold for subtropical forests, significant N leaching still occurred. Excess export of N occurred in the upper soil layer (0–15 cm), reaching 6.86 ± 1.54 kg N/ha/yr, while the deeper soil (15–30 cm) was net sink of N as 8.29 ± 1.71 kg N/ha/yr. Similarly, S was excessively exported from the upper soil with net flux of 14.7 ± 3.15 kg S/ha/yr, while up to 6.37 ± 3.18 kg S/ha/yr of S was retained in the deeper soil. The significant N and S leaching under declined depositions suggested that this site possibly underwent a transition state, recovering from historically high acid deposition. Furthermore, the rainfall intensity remarkably regulated leaching and retention of SO42− and DIN at this site. The impacts of climate changes on N and S dynamics require further long-term monitoring in subtropical forests.

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COMPLEX MONITORING OF GEOCRYOLOGICAL STRUCTURE AND GROUND TEMPERATURE REGIME OF THE ARCTIC COASTAL ZONE IN THE AREAS OF INFRASTRUCTURE CONSTRUCTION

Proceedings of International Conference "Managinag risks to coastal regions and communities in a changinag world" (EMECS'11 - SeaCoasts XXVI) ◽

10.21610/conferencearticle_58b43164271b0 ◽

2017 ◽

Author(s):

Osip Kokin ◽

Stanislav Ogorodov ◽

Nataliya Belova ◽

...

Keyword(s):

Steady State ◽

Coastal Zone ◽

Temperature Regime ◽

The Arctic ◽

Negative Consequences ◽

Fast Ice ◽

Field Works ◽

Complex Monitoring ◽

Planning And Construction

The research of geocryological structure of the coasts is important in the planning and construction of infrastructure in permafrost zone. Long-term monitoring of temperature regime of the Arctic coastal zone soils needs to predict the steady state of the object during its operation and prevent possible negative consequences resulting from interruption of the steady state. It is especially important in conditions of today's climate change, as well as the possibility of warming effect of engineering facilities (for example pipelines). The results of a study of the coastal seasonally frozen cap, formed in the contact zone of freezing fast ice to the bottom are presented by the examples of the Mys Kamenniy settlement at the Gulf of Ob coast (Kara Sea) and Varandey settlement at the Pechora Sea areas. The technology of the monitoring station establishment for the geocryological statement and temperature regime of the Arctic coastal zone observations is proposed based on the conducted field works experience.

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Nitrogen deposition and effects on European forests

Environmental Reviews ◽

10.1139/a00-006 ◽

2000 ◽

Vol 8 (2) ◽

pp. 65-93 ◽

Cited By ~ 63

Author(s):

J W Erisman ◽

W de Vries

Keyword(s):

Species Diversity ◽

Nitrogen Deposition ◽

Forest Ecosystems ◽

N Deposition ◽

Ground Vegetation ◽

N Saturation ◽

Input Output ◽

Soil Response ◽

Field Evidence ◽

The Impact

Hypotheses about the impacts of elevated atmospheric deposition of nitrogen on the forest ecosystem include an increased sensitivity to natural stress, impacts on roots, reduced species diversity of the ground vegetation, reduced growth, and unbalanced nutritional status due to eutrophication and acidification. The impact of N deposition has gained in ecological importance during recent decades, in part due to the steady decline in S emissions. Results of throughfall and deposition measurements at 163 plots in Europe show that total deposition of S and N compounds ranged from 100 to 3000 mol ha1 yr1 in approximately 90% of the plots, but values up to 40008000 mol ha1 yr1 were also observed. Approximately 50% of the plots received N inputs, dominated by NH4, above 1000 mol ha1 yr1, which is a deposition level at which species diversity of the ground vegetation may be at risk. Results of inputoutput budgets for plots concentrated in Northern and Western Europe indicate that nitrate leaching starts to occur at throughfall inputs above 10 kg ha1 yr1, specifically in soils with C/N ratios in the humus layer below 25. Examples are given of field evidence for impacts of elevated N deposition, including elevated N contents in foliage and soil, Al release in soil response to increased nitrate concentrations, reduced shoot/root ratios, and a reduction in species diversity. Although knowledge about the response of forest ecosystems to N inputs has increased over the last decade, there is still a lack of information on the dynamics of N accumulation and related critical N loads in a range of environmental conditions. Furthermore, a European-wide perspective of N saturation in forest ecosystems is still lacking.Key words: nitrogen, deposition, inputoutput budgets, nitrogen status, forests, effects.

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Quantification of nitrate leaching from forest soils on a national scale in The Netherlands

Hydrology and Earth System Sciences ◽

10.5194/hess-8-813-2004 ◽

2004 ◽

Vol 8 (4) ◽

pp. 813-822 ◽

Cited By ~ 8

Author(s):

J. Kros ◽

A. Tietema ◽

J. P. Mol-Dijkstra ◽

W. de Vries

Keyword(s):

Steady State ◽

Regression Model ◽

Nitrogen Deposition ◽

Dynamic Model ◽

Critical Loads ◽

Forest Ecosystems ◽

Dynamic Models ◽

National Scale ◽

Regional Variability ◽

Nitrate Concentrations

Abstract. To evaluate the effects of nitrogen (N) emission policies, reliable information on nitrate concentrations and leaching fluxes from forest ecosystems is necessary. Insight into the regional variability of nitrate concentrations, to support local policy on emission abatement strategies is especially desirable. In this paper, three methods for the calculation of a spatial distribution of soil nitrate concentrations in Dutch forest ecosystems are compared. These are (i) a regression model based on observed nitrate concentrations and additional data on explanatory variables such as soil type, tree species and nitrogen deposition (ii) a semi-empirical dynamic model WANDA, and (iii) a process-oriented dynamic model SMART2. These two dynamic models are frequently used to evaluate the effects of reductions in nitrogen deposition at scales ranging from regional to countrywide. The results of the regression model evaluated the performance of the two dynamic models. Furthermore, the results of the three methods are compared with the steady-state approach currently used for the derivation of nitrogen critical loads. Both dynamic models, in the form of cumulative distribution functions, give similar results on a national scale. Regional variability is predicted differently by both models. Discrepancies are caused mainly by a difference in handling forest filtering and denitrification. All three methods show that, despite the high nitrogen inputs, Dutch forests still accumulate more N than they release. This implies that, in respect of groundwater quality, presently acceptable nitrogen deposition is higher than the (long-term) critical loads. However, in areas with high atmospheric nitrogen input, all three methods indicate that the EU standard for nitrate in groundwater (50 mg NO3 l–1) is exceeded. Steady-state with nitrogen deposition seems to have been reached in about 10% of the forested area, with a nitrate concentration greater than 50 mg NO3–1. Keywords: soil modelling, up-scaling, model validation, critical load

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

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f02-092 ◽

2002 ◽

Vol 59 (8) ◽

pp. 1287-1295 ◽

Cited By ~ 33

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 19761999. 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·m2·year1. As a result of the declining deposition, the portion of lakes with critical load exceedances has dropped substantially, from 7482% in the four sensitive regions in 1976 to 1126% 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·m2·year1 (11 kg S·ha1·year1) to prevent critical load exceedance.

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