Open Field Deposition Research Articles

Good Agreement Between Modeled and Measured Sulfur and Nitrogen Deposition in Europe, in Spite of Marked Differences in Some Sites

Atmospheric nitrogen and sulfur deposition is an important effect of atmospheric pollution and may affect forest ecosystems positively, for example enhancing tree growth, or negatively, for example causing acidification, eutrophication, cation depletion in soil or nutritional imbalances in trees. To assess and design measures to reduce the negative impacts of deposition, a good estimate of the deposition amount is needed, either by direct measurement or by modeling. In order to evaluate the precision of both approaches and to identify possible improvements, we compared the deposition estimates obtained using an Eulerian model with the measurements performed by two large independent networks covering most of Europe. The results are in good agreement (bias <25%) for sulfate and nitrate open field deposition, while larger differences are more evident for ammonium deposition, likely due to the greater influence of local ammonia sources. Modeled sulfur total deposition compares well with throughfall deposition measured in forest plots, while the estimate of nitrogen deposition is affected by the tree canopy. The geographical distribution of pollutant deposition and of outlier sites where model and measurements show larger differences are discussed.

Composting and Methane Emissions of Coffee By-Products

In the last 20 years, the demand for coffee production has increased detrimentally, heightening the need for production, which is currently driving the increase in land cultivation for coffee. However, this increase in production ultimately leads to the amplification of waste produced. This study aims to develop an experimental methodology for sustainable coffee by-products (Pulp (CP)) in Costa Rica for nutrient-rich compost. The performance of the experiments is to explore and optimize composting processes following its key parameters. This will allow quantifying the emissions rate to obtain an emission factor for CP during the open composting process and optimizing the conditions to minimize CH4 emissions using P and green waste (GW) materials. Five CP and GW mixtures were analyzed for the composting process for ten weeks, acting P as primary input material as a by-product. Quantification of the methane emissions was performed in two areas: composting area and open field deposition. Peak temperatures of compost appeared at twenty-five days for control and five days for GW added treatments. CP emission factors provide a similar result with the standard values recommended by the literature, accomplishing the emission reductions. Thus, this study designed and validated a sustainable protocol for transforming coffee by-products into compost.

Comparison of Methods for the Estimation of Total Inorganic Nitrogen Deposition to Forests in Germany

A reliable quantification of total inorganic nitrogen (TIN) deposition to forests is required for the evaluation of ecological effects of TIN inputs to forests and to monitor the success of clean-air policy. As direct measurements are scarce, different modeling approaches have been developed to estimate TIN deposition to forests. Three common methods are the (i) “canopy budget model,” (ii) “inferential method,” and (iii) “emission based estimates” using a chemical transport model. Previous studies have reported considerable and site-specific differences between these methods, complicating the interpretation of results. We use data from more than 100 German intensive forest monitoring sites over a period of 16 years for a cross-comparison of these approaches. Non-linear mixed-effect models were applied to evaluate how factors like meteorology, terrain and stand characteristics affect discrepancies between the model approaches. Taking into account the uncertainties in deposition estimates, there is a good agreement between the canopy budget and the inferential method when using semi-empirical correction factors for deposition velocity. Wet deposition estimates of the emission based approach were in good agreement with wet-only corrected bulk open field deposition measurements used by the other two approaches. High precipitation amounts partly explained remaining differences in wet deposition. Larger discrepancies were observed when dry deposition estimates are compared between the emissions based approach and the other two approaches, which appear to be related to a combination of meteorological conditions and tree species effects.

Impacts of land use policy on the recovery of mountain catchments from acidification

Watersheds in mountainous regions provide water resources available to large downstream areas. Acidification of mountain waters leads to problems in water quality with impacts to drinking water supply and biodiversity conservation. Effects of the land use policy, air pollution and forest canopy on acidification of headwater catchments in the Jizera Mountains were studied in the period of 1982–2015. The archive of LANDSAT imagery and a field inventory was used to reconstruct changes in the vegetative cover. The atmospheric deposition of acidic substances (sulphate, nitrate, and ammonia) in studied catchments was approximated by a spatial interpolation. The acid atmospheric load culminated in the 1980s. The Helsinki protocol on the reduction of sulphur emissions lead to a reduced open field deposition of sulphur, but, the atmospheric deposition of sulphur and nitrogen is also controlled by the vegetative canopy. A drop in the acid load and a recovery of surface waters from acidification were observed with the harvest of spruce forests. The existing land use policy, institutes of ‘protected headwater area’ and ‘zones of hygienic protection’ (Water Act 138/1973) were ineffective in this situation. In a catchment scale, the proposed scenario of structured forestry zones (respecting riparian buffers, stability of steep slopes, significant fog drip areas, peat spots) can decrease the annual load of sulphur and nitrogen by approx. 30%.

Nitrogen deposition along differently exposed slopes in the Bavarian Alps

The Alps are affected by high nitrogen deposition, particularly in the fringe of the Northern and Southern Alps. In the framework of a two-year monitoring study performed in 2010 and 2011, we investigated the ammonia and nitrogen dioxide air concentration and ammonium and nitrate deposition at different altitudes between 700 and 1600ma.s.l. in the Garmisch-Partenkirchen district in the Upper Bavaria region (Germany). Four-weekly measurements of deposition collected with bulk open field samplers and under-crown were performed in a profile perpendicular to the axis of the Loisach valley; measurements were conducted at eight sites. Whereas open field deposition ranged from 5 to 11kgha−1a−1, nitrogen throughfall has reached up to 21kgha−1a−1. Data from the valley and the slopes were compared with measurements performed on the platform of the Environmental Research Station Schneefernerhaus (Zugspitze) at an altitude of 2650ma.s.l. For the rough estimation of the total yearly deposition rate of nitrogen, the canopy uptake model was applied. By regarding nitrogen uptake by the trees, total deposition can exceed the throughfall in all sites by up to 50%. Additionally, we estimated the total deposition from the sum of wet and dry deposition. On the one side, the wet deposition could be extrapolated from the open field deposition. On the other side, we used the inferential method to calculate the dry deposition on the basis of NH3 and NO2 air concentrations and their literature based deposition velocities. Since fixed deposition velocities are inappropriate particularly in complex orography, we tried to find correction factors based upon terrain characteristics and meteorological considerations. Temperature monitoring at the eight sites and wind measurements at two sites provided some evidence for the semi-empirical parameterization. Due to numerous imponderabilities, the results of the two methods were not consistent for all sites.

The effect of forest type on throughfall deposition and seepage flux: a review

Converting deciduous forests to coniferous plantations and vice versa causes environmental changes, but till now insight into the overall effect is lacking. This review, based on 38 case studies, aims to find out how coniferous and deciduous forests differ in terms of throughfall (+stemflow) deposition and seepage flux to groundwater. From the comparison of coniferous and deciduous stands at comparable sites, it can be inferred that deciduous forests receive less N and S via throughfall (+stemflow) deposition on the forest floor. In regions with relatively low open field deposition of atmospheric N (<10 kg N ha(-1) year(-1)), lower NH(4)(+) mean throughfall (+stemflow) deposition was, however, reported under conifers compared to deciduous forest, while in regions with high atmospheric N pollution (>10 kg N ha(-1) year(-1)), the opposite could be concluded. The higher the open field deposition of NH(4)(+), the bigger the difference between the coniferous and deciduous throughfall (+stemflow) deposition. Furthermore, it can be concluded that canopy exchange of K(+), Ca(2+) and Mg(2+) is on average higher in deciduous stands. The significantly higher stand deposition flux of N and S in coniferous forests is reflected in a higher soil seepage flux of NO(3)(-), SO(4)(2-), K(+), Ca(2+), Mg(2+) and Al(III). Considering a subset of papers for which all necessary data were available, a close relationship between throughfall (+stemflow) deposition and seepage was found for N, irrespective of the forest type, while this was not the case for S. This review shows that the higher input flux of N and S in coniferous forests clearly involves a higher seepage of NO(3)(-) and SO(4)(2-) and accompanying cations K(+), Ca(2+), Mg(2+) and Al(III) into the groundwater, making this forest type more vulnerable to acidification and eutrophication compared to the deciduous forest type.

The Geochemistry of Ombrotrophic Sphagnum Species Growing in Different Microhabitats Of Eight German and Belgian Peat Bogs and the Regional Atmospheric Deposition

Comparing today’s atmospheric deposition records with the elemental concentration and the net-uptake rates of ombrotrophic Sphagnum mosses from eight German and Belgian peat bogs revealed that most of all the quality and number of regularly obtained deposition monitoring data is not satisfactory. Moreover, it seems likely that the deposition rate, determined by Sphagnum mosses, does not reliably reflect the record of the total open field deposition indicated by the deposition monitoring data. The moss data, too, show a distinct spatial variability possibly because the geochemistry of peat mosses differs according to the annual growth in height, the total surface area and the surface roughness of the receptor ‘peat moss’ (special interception deposition). Increased Ti concentration values, for example, combined with a high annual growth rate in height at the hollow moss S. cuspidatum resulted in generally high Ti net-uptake rates and a high Ti inventory (total Ti in sample). We, therefore, suggest that productive Sphagnum species might be able to fix more Ti particles on their larger surface area than less productive species do. Moreover, the results demonstrate that for reliably calculating Sphagnum elemental net-uptake rates, as well as for all quantification of Sphagnum or peat geochemistry on a time and area basis, an accurate knowledge of the period the collected samples were exposed to atmospheric deposition is required. In particular, to do reliable reconstructions of past atmospheric deposition rates using peat deposits, further studies are needed to precisely specify the spatial variability in the geochemistry of living Sphagnum mosses.

The chemical composition of throughfall beneath oak, birch and pine canopies in Northwest Germany

The chemical composition of rainwater is altered upon its passage through tree canopies. In order to investigate how rainwater chemistry is affected by canopy-dependent processes in characteristic forest types of Northwest German sandy lowland regions – oak–birch-forests, Betula pubescens Ehrh. swamp forests, and stands of Pinus sylvestris L. – comparative studies on the chemical composition of throughfall were carried out at seven forest sites, situated in close proximity within a nature reserve. Additionally, rainwater was sampled at three heathland sites for analysis of open-field precipitation and at three sites along an oak–birch-forest edge. Throughfall concentrations of most of the parameters analysed were significantly higher than open-field concentrations, especially with regard to electric conductivity, NH4-N, K+, and KMnO4-index. Ion concentrations in throughfall were the lowest in a 10-year-old stand of Betula pendula Roth. and Pinus sylvestris and in a Betula pubescens swamp forest and were highest beneath a stand of Pinus sylvestris. Except for Na+, Cl−, and NO 3 − , ion concentrations in both throughfall and open-field precipitation increased during the growing season (May–October). In throughfall, Ca2+, Mg2+, K+, and Mn2+ were strongly correlated. Enrichment ratios between throughfall and open-field deposition varied among sites and elements and were the highest for K‰+, Mg2‰+, and Mn2‰+. Estimates of canopy leaching indicated high leaching rates of K‰+ and Mn2‰+ and moderate leaching of Mg2‰+. The contribution of foliar leaching to throughfall deposition was higher at the deciduous than at the coniferous stands.

Fog frequency and chemical composition of fog water—a relevant contribution to atmospheric deposition in the eastern Erzgebirge, Germany

Abstract After successful air quality control in Central Europe has taken effect and previous problems related to atmospheric deposition supposedly solved, a new study on fog-related inputs to mountainous areas yields some surprises. The hydrological relevance of fog reaches significant levels at altitudes above 800 m a.s.l. In this study, some 25% of the water input derived from fog, equivalent to 152 fog hours per month (10% of which were sampled; 8 sites, one sampler each). The fog droplets dissolve more aerosol particles and generally contain significantly higher ion concentrations than rainwater. The related enrichment factors lie between 2.5 and 38, with 6–7 for the most relevant species. For some of the potentially noxious substances, concentrations excel the thresholds that protect, e.g., forest health. Even though fog chemistry has seen major changes as of the 1980s, and ion concentrations did decrease, the input still is relevant and contributes to a continuing strain. Interestingly, forests themselves alter the ionic composition of fog water, and a distinct trend becomes visible from open field deposition to forest interior sites.

Atmospheric fluxes of persistent semivolatile organic pollutants to a forest ecological system at the Swedish west coast and accumulation in spruce needles

Measurements of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) have been carried out in a forested area at Lake Gårdsjön. The overall aim of this study was to identify the importance of atmospheric fluxes for the occurrence of persistent semivolatile organic compounds in a forest at the Swedish west coast and to measure the major pathways of circulation and accumulation of these contaminants within a terrestrial ecosystem. The sampling was undertaken in campaigns chosen to represent different seasons. The measurements carried out in 1991–94 were concentrated on the uptake of persistent organic pollutants (POPs) in spruce needles in relation to concentrations in air and amounts in deposition, while the measurements undertaken in 1995 also included sampling of throughfall, litterfall and run-off. The concentrations of PCBs and PAHs in the different compartments have been used to identify important reservoirs and to estimate the annual fluxes of these compounds. The results of measurements showed that atmospheric fluxes are important for the occurrence of PCBs and PAHs in forest at the Swedish west coast. A seasonal variation was found in the atmospheric concentrations, and the ambient temperature was important for PCBs in air. The amounts of PAHs and PCBs deposited to the Gårdsjö area (open field) were similar to those obtained during measurements at coastal- and sea-based sites at the Swedish west coast. Soot episodes at the Swedish west coast affected the deposition fluxes of POPs in the forest. There seemed to be both an accumulation and release of POPs in different compartments in this forest ecosystem. A greater deposition of POPs was found in the forest soil via throughfall compared with the open field deposition. An estimate of the fluxes of PAHs and PCBs in the catchment area in a forest showed that the soil is the main reservoir for POPs in this area.

Study on throughfall deposition in two north Italian forest sites (Valtellina, Lombardy)

Throughfall and open field deposition were sampled in two alpine forest catchments in Lombardy characterized by a different degrees of forest decline. The results of two years sampling revealed some interesting differences in the chemical composition of throughfall deposition between the two study areas. The higher concentrations of potassium, calcium, nitrate and dissolved organic carbon (DOC) measured in the Alpe Culino throughfall samples, indicate that the phenomenon of foliar leaching is marked in the area and can be related to the greater forest damage. Large spatial variability of throughfall deposition fluxes within Alpe Culino forest was observed.

Role of vegetation cover in the biogeochemical balances of a small afforested catchment in southeastern Spain

The budgets of major dissolved nutrients have been determined in a small micaschist catchment (0.34 km 2) covered with Mediterranean shrubs and afforested pines at 1560 m altitude in the Filabres range (southeast Spain). The climate is semiarid with 395 mm annual rainfall and 12°C annual mean temperature. During the hydrological year 1988–1989, major element concentrations in open field precipitation, throughfall, stemflow and runoff were recorded as well as the element fluxes of the main solutes. The total rainfall recorded during the sampling year was 650 mm of which 86% was lost through evapotranspiration and 14% through runoff. Mean annual rainfall interception is estimated as 15% and net rainfall reaching the soil is divided between 90% throughfall and 10% stemflow. Two methods were applied to compute bulk precipitation inputs to the ionic balances: (I) bulk open field deposition was estimated from data provided by open field polyethylene collectors (bulk open field precipitation inputs); (II) net throughfall and stemflow were corrected for canopy leaching. The results show that the total deposition calculated using balance (II) is higher than that calculated by (I); the effect of canopy surfaces in scavenging atmospheric dry fallouts and gases is identified in a more efficient way than by simple polyethylene collectors. When comparing both methods of computing balances in several environments, using published data, the authors conclude that the plant canopy effect is larger in sermiarid areas with dusty atmospheres and in industrial regions with higher concentrations of sulphur. These conclusions suggest that the retention of nutrients within the ecosystem may be more widespread than was previously thought. This calls for more research on the assessment of biomass removal and the dynamics of intermediate pools (precipitates). Consequently, it throws doubts on most of the figures available for catchment weathering rates; these were often estimated by difference between bulk open field precipitation inputs measured with polyethylene collectors and runoff outputs.