Atmospheric Deposition Effects on Surface Waters, Soils, and Forest Productivity

Author(s):  
Gregory B. Lawrence ◽  
Kristiina A. Vogt ◽  
Daniel J. Vogt ◽  
Joel P. Tilley ◽  
Philip M. Wargo ◽  
...  
2014 ◽  
Vol 11 (17) ◽  
pp. 4913-4924 ◽  
Author(s):  
F. Korth ◽  
B. Deutsch ◽  
C. Frey ◽  
C. Moros ◽  
M. Voss

Abstract. Nitrate (NO3−) is the major nutrient responsible for coastal eutrophication worldwide and its production is related to intensive food production and fossil-fuel combustion. In the Baltic Sea NO3− inputs have increased 4-fold over recent decades and now remain constantly high. NO3− source identification is therefore an important consideration in environmental management strategies. In this study focusing on the Baltic Sea, we used a method to estimate the proportional contributions of NO3− from atmospheric deposition, N2 fixation, and runoff from pristine soils as well as from agricultural land. Our approach combines data on the dual isotopes of NO3− (δ15N-NO3− and δ18O-NO3−) in winter surface waters with a Bayesian isotope mixing model (Stable Isotope Analysis in R, SIAR). Based on data gathered from 47 sampling locations over the entire Baltic Sea, the majority of the NO3− in the southern Baltic was shown to derive from runoff from agricultural land (33–100%), whereas in the northern Baltic, i.e. the Gulf of Bothnia, NO3− originates from nitrification in pristine soils (34–100%). Atmospheric deposition accounts for only a small percentage of NO3− levels in the Baltic Sea, except for contributions from northern rivers, where the levels of atmospheric NO3− are higher. An additional important source in the central Baltic Sea is N2 fixation by diazotrophs, which contributes 49–65% of the overall NO3− pool at this site. The results obtained with this method are in good agreement with source estimates based upon δ15N values in sediments and a three-dimensional ecosystem model, ERGOM. We suggest that this approach can be easily modified to determine NO3− sources in other marginal seas or larger near-coastal areas where NO3− is abundant in winter surface waters when fractionation processes are minor.


2013 ◽  
Vol 10 (7) ◽  
pp. 12491-12527 ◽  
Author(s):  
C. Guieu ◽  
F. Dulac ◽  
C. Ridame ◽  
P. Pondaven

Abstract. The main goal of the project DUNE was to estimate the impact of atmospheric deposition on an oligotrophic ecosystem based on mesocosm experiments simulating strong atmospheric inputs of Aeolian dust. Atmospheric deposition is now recognized as a significant source of macro- and micro-nutrients for the surface ocean, but the quantification of its role on the biological carbon pump is still poorly determined. We proposed in DUNE to investigate the role of atmospheric inputs on the functioning of an oligotrophic system particularly well adapted to this kind of study: the Mediterranean Sea. The Mediterranean Sea – etymologically, sea surrounded by land – is submitted to atmospheric inputs that are very variable both in frequency and intensity. During the thermal stratification period, only atmospheric deposition is prone to fertilize Mediterranean surface waters which has become very oligotrophic due to the nutrient depletion (after the spring bloom). This paper describes the objectives of DUNE and the implementation plan of a series of mesocosms experiments during which either wet or dry and a succession of two wet deposition fluxes of 10 g m−2 of Saharan dust have been simulated. After the presentation of the main biogeochemical initial conditions of the site at the time of each experiment, a general overview of the papers published in this special issue is presented, including laboratory results on the solubility of trace elements in erodible soils in addition to results from the mesocosm experiments. Our mesocosm experiments aimed at being representative of real atmospheric deposition events onto the surface of oligotrophic marine waters and were an original attempt to consider the vertical dimension in the study of the fate of atmospheric deposition within surface waters. Results obtained can be more easily extrapolated to quantify budgets and parameterize processes such as particle migration through a "captured water column". The strong simulated dust deposition events were found to impact the dissolved concentrations of inorganic dissolved phosphorus, nitrogen, iron and other trace elements. In the case of Fe, adsorption on sinking particles yields a decrease in dissolved concentration unless binding ligands were produced following a former deposition input and associated fertilization. For the first time, a quantification of the C export induced by the aerosol addition was possible. Description and parameterization of biotic (heterotrophs and autotrophs, including diazotrophs) and abiotic processes (ballast effect due to lithogenic particles) after dust addition in sea surface water, result in a net particulate organic carbon export in part controlled by the "lithogenic carbon pump".


2014 ◽  
Vol 11 (2) ◽  
pp. 425-442 ◽  
Author(s):  
C. Guieu ◽  
F. Dulac ◽  
C. Ridame ◽  
P. Pondaven

Abstract. The main goal of project DUNE was to estimate the impact of atmospheric deposition on an oligotrophic ecosystem based on mesocosm experiments simulating strong atmospheric inputs of eolian mineral dust. Our mesocosm experiments aimed at being representative of real atmospheric deposition events onto the surface of oligotrophic marine waters and were an original attempt to consider the vertical dimension after atmospheric deposition at the sea surface. This introductory paper describes the objectives of DUNE and the implementation plan of a series of mesocosm experiments conducted in the Mediterranean Sea in 2008 and 2010 during which either wet or dry and a succession of two wet deposition fluxes of 10 g m−2 of Saharan dust have been simulated based on the production of dust analogs from erodible soils of a source region. After the presentation of the main biogeochemical initial conditions of the site at the time of each experiment, a general overview of the papers published in this special issue is presented. From laboratory results on the solubility of trace elements in dust to biogeochemical results from the mesocosm experiments and associated modeling, these papers describe how the strong simulated dust deposition events impacted the marine biogeochemistry. Those multidisciplinary results are bringing new insights into the role of atmospheric deposition on oligotrophic ecosystems and its impact on the carbon budget. The dissolved trace metals with crustal origin – Mn, Al and Fe – showed different behaviors as a function of time after the seeding. The increase in dissolved Mn and Al concentrations was attributed to dissolution processes. The observed decrease in dissolved Fe was due to scavenging on sinking dust particles and aggregates. When a second dust seeding followed, a dissolution of Fe from the dust particles was then observed due to the excess Fe binding ligand concentrations present at that time. Calcium nitrate and sulfate were formed in the dust analog for wet deposition following evapocondensation with acids for simulating cloud processing by polluted air masses under anthropogenic influence. Using a number of particulate tracers that were followed in the water column and in the sediment traps, it was shown that the dust composition evolves after seeding by total dissolution of these salts. This provided a large source of new dissolved inorganic nitrogen (DIN) in the surface waters. In spite of this dissolution, the typical inter-elemental ratios in the particulate matter, such as Ti / Al or Ba / Al, are not affected during the dust settling, confirming their values as proxies of lithogenic fluxes or of productivity in sediment traps. DUNE experiments have clearly shown the potential for Saharan wet deposition to modify the in situ concentrations of dissolved elements of biogeochemical interest such as Fe and also P and N. Indeed, wet deposition yielded a transient increase in dissolved inorganic phosphorus (DIP) followed by a very rapid return to initial conditions or no return to initial conditions when a second dust seeding followed. By transiently increasing DIP and DIN concentrations in P- and N-starved surface waters of the Mediterranean Sea, wet deposition of Saharan dust can likely relieve the potential P and/or N limitation of biological activity; this has been directly quantified in terms of biological response. Wet deposition of dust strongly stimulated primary production and phytoplanktonic biomass during several days. Small phytoplankton (< 3 μm) was more stimulated after the first dust addition, whereas the larger size class (> 3 μm) significantly increased after the second one, indicating that larger-sized cells need further nutrient supply in order to be able to adjust their physiology and compete for resource acquisition and biomass increase. Among the microorganisms responding to the atmospheric inputs, diazotrophs were stimulated by both wet and dry atmospheric deposition, although N2 fixation was shown to be only responsible for a few percent of the induced new production. Dust deposition modified the bacterial community structure by selectively stimulating and inhibiting certain members of the bacterial community. The microbial food web dynamics were strongly impacted by dust deposition. The carbon budget indicates that the net heterotrophic character (i.e., ratio of net primary production to bacteria respiration < 1) of the tested waters remained (or was even increased) after simulated wet or dry deposition despite the significant stimulation of autotrophs after wet events. This indicates that the oligotrophic tested waters submitted to dust deposition are a net CO2 source. Nonetheless, the system was able to export organic material, half of it being associated with lithogenic particles through aggregation processes between lithogenic particles and organic matter. These observations support the "ballast" hypothesis and suggest that this "lithogenic carbon pump" could represent a major contribution of the global carbon export to deep waters in areas receiving high rates of atmospheric deposition. Furthermore, a theoretical microbial food web model showed that, all other things being equal, carbon, nitrogen and phosphorus stoichiometric mismatch along the food chain can have a substantial impact on the ecosystem response to nutrient inputs from dusts, with changes in the biomass of all biological compartments by a factor of ~ 2–4, and shifts from net autotrophy to net heterotrophy. Although the model was kept simple, it highlights the importance of stoichiometric constrains on the dynamics of microbial food webs.


Author(s):  
Dave. Humphries ◽  
Anne-Marie Anderson ◽  
Gary. Byrtus ◽  
◽  
◽  
...  

2016 ◽  
Author(s):  
M. Camino-Serrano ◽  
E. Graf Pannatier ◽  
S. Vicca ◽  
S. Luyssaert ◽  
M. Jonard ◽  
...  

Abstract. Dissolved organic carbon (DOC) in soil solution is connected to DOC in surface waters through hydrological flows. Therefore, it is expected that long-term dynamics of DOC in surface waters reflect DOC trends in soil solution. However, a multitude of site-studies has failed so far to establish consistent trends in soil solution DOC, whereas increasing concentrations in European surface waters over the past decades appear to be the norm, possibly as a result from acidification recovery. The objectives of this study were therefore to understand the long-term trends of soil solution DOC from a large number of European forests (ICP Forests Level II plots) and determine their main physico-chemical and biological controls. We applied trend analys is at two levels: 1) to the entire European dataset and 2) to the individual time series and related trends with plot characteristics, i.e., soil and vegetation properties, soil solution chemistry and atmospheric deposition loads. Analyses of the entire dataset showed an overall increasing trend in DOC concentrations in the organic layers, but, at individual plots and depths, there was no clear overall trend in soil solution DOC across Europe with temporal slopes of soil solution DOC ranging between −16.8 % yr−1 and +23 % yr−1 (median= +0.4 % yr−1). The non-significant trends (40 %) outnumbered the increasing (35 %) and decreasing trends (25 %) across the 97 ICP Forests Level II sites. By means of multivariate statistics, we found increasing DOC concentrations with increasing mean nitrate (NO3−) deposition and decreasing DOC concentrations with decreasing me an sulphate (SO42−) deposition, with the magnitude of these relationships depending on plot deposition history. While the attribution of increasing trends in DOC to the reduct ion of SO42− deposition could be confirmed in N-poorer forests, in agreement with observations in surface waters, this was not the case in N-richer forests. In conclusion, long-term trends of soil solution DOC reflected the interactions between controls acting at local (soil and vegetation properties) and regional (atmospheric deposition of SO42− and inorganic N) scales.


Ecotoxicology ◽  
2020 ◽  
Vol 29 (10) ◽  
pp. 1565-1589
Author(s):  
D. C. Evers ◽  
A. K. Sauer ◽  
D. A. Burns ◽  
N. S. Fisher ◽  
D. C. Bertok ◽  
...  

AbstractMercury (Hg) pollution is an environmental problem that adversely affects human and ecosystem health at local, regional, and global scales—including within New York State. More than two-thirds of the Hg currently released to the environment originates, either directly or indirectly, from human activities. Since the early 1800s, global atmospheric Hg concentrations have increased by three- to eight-fold over natural levels. In the U.S., atmospheric emissions and point-source releases to waterways increased following industrialization into the mid-1980s. Since then, water discharges have largely been curtailed. As a result, Hg emissions, atmospheric concentrations, and deposition over the past few decades have declined across the eastern U.S. Despite these decreases, Hg pollution persists. To inform policy efforts and to advance public understanding, the New York State Energy Research and Development Authority (NYSERDA) sponsored a scientific synthesis of information on Hg in New York State. This effort includes 23 papers focused on Hg in atmospheric deposition, water, fish, and wildlife published in Ecotoxicology. New York State experiences Hg contamination largely due to atmospheric deposition. Some landscapes are inherently sensitive to Hg inputs driven by the transport of inorganic Hg to zones of methylation, the conversion of inorganic Hg to methylmercury, and the bioaccumulation and biomagnification along food webs. Mercury concentrations exceed human and ecological risk thresholds in many areas of New York State, particularly the Adirondacks, Catskills, and parts of Long Island. Mercury concentrations in some biota have declined in the Eastern Great Lakes Lowlands and the Northeastern Highlands over the last four decades, concurrent with decreases in water releases and air emissions from regional and U.S. sources. However, widespread changes have not occurred in other ecoregions of New York State. While the timing and magnitude of the response of Hg levels in biota varies, policies expected to further diminish Hg emissions should continue to decrease Hg concentrations in food webs, yielding benefits to the fish, wildlife, and people of New York State. Anticipated improvements in the Hg status of aquatic ecosystems are likely to be greatest for inland surface waters and should be roughly proportional to declines in atmospheric Hg deposition. Efforts that advance recovery from Hg pollution in recent years have yielded significant progress, but Hg remains a pollutant of concern. Indeed, due to this extensive compilation of Hg observations in biota, it appears that the extent and intensity of the contamination on the New York landscape and waterscape is greater than previously recognized. Understanding the extent of Hg contamination and recovery following decreases in atmospheric Hg deposition will require further study, underscoring the need to continue existing monitoring efforts.


2016 ◽  
Vol 13 (19) ◽  
pp. 5567-5585 ◽  
Author(s):  
Marta Camino-Serrano ◽  
Elisabeth Graf Pannatier ◽  
Sara Vicca ◽  
Sebastiaan Luyssaert ◽  
Mathieu Jonard ◽  
...  

Abstract. Dissolved organic carbon (DOC) in surface waters is connected to DOC in soil solution through hydrological pathways. Therefore, it is expected that long-term dynamics of DOC in surface waters reflect DOC trends in soil solution. However, a multitude of site studies have failed so far to establish consistent trends in soil solution DOC, whereas increasing concentrations in European surface waters over the past decades appear to be the norm, possibly as a result of recovery from acidification. The objectives of this study were therefore to understand the long-term trends of soil solution DOC from a large number of European forests (ICP Forests Level II plots) and determine their main physico-chemical and biological controls. We applied trend analysis at two levels: (1) to the entire European dataset and (2) to the individual time series and related trends with plot characteristics, i.e., soil and vegetation properties, soil solution chemistry and atmospheric deposition loads. Analyses of the entire dataset showed an overall increasing trend in DOC concentrations in the organic layers, but, at individual plots and depths, there was no clear overall trend in soil solution DOC. The rate change in soil solution DOC ranged between −16.8 and +23 % yr−1 (median  = +0.4 % yr−1) across Europe. The non-significant trends (40 %) outnumbered the increasing (35 %) and decreasing trends (25 %) across the 97 ICP Forests Level II sites. By means of multivariate statistics, we found increasing trends in DOC concentrations with increasing mean nitrate (NO3−) deposition and increasing trends in DOC concentrations with decreasing mean sulfate (SO42−) deposition, with the magnitude of these relationships depending on plot deposition history. While the attribution of increasing trends in DOC to the reduction of SO42− deposition could be confirmed in low to medium N deposition areas, in agreement with observations in surface waters, this was not the case in high N deposition areas. In conclusion, long-term trends of soil solution DOC reflected the interactions between controls acting at local (soil and vegetation properties) and regional (atmospheric deposition of SO42− and inorganic N) scales.


2014 ◽  
Vol 11 (4) ◽  
pp. 5869-5901 ◽  
Author(s):  
F. Korth ◽  
B. Deutsch ◽  
C. Frey ◽  
C. Moros ◽  
M. Voss

Abstract. Nitrate (NO3−) is the major nutrient responsible for coastal eutrophication worldwide and its production is related to intensive food production and fossil-fuel combustion. In the Baltic Sea NO3−inputs have increased four-fold over the last decades and now remain constantly high. NO3− source identification is therefore an important consideration in environmental management strategies. In this study focusing on the Baltic Sea, we used a method to estimate the proportional contributions of NO3− from atmospheric deposition, N2 fixation, and runoff from pristine soils as well as from agricultural land. Our approach combines data on the dual isotopes of NO3− (δ15N-NO3− and δ18O-NO3−) in winter surface waters with a Bayesian isotope mixing model (Stable Isotope Analysis in R, SIAR). Based on data gathered from 46 sampling locations over the entire Baltic Sea, the majority of the NO3− in the southern Baltic was shown to derive from runoff from agricultural land (30–70%), whereas in the northern Baltic, i.e., the Gulf of Bothnia, NO3− originates from nitrification in pristine soils (47–100%). Atmospheric deposition accounts for only a small percentage of NO3− levels in the Baltic Sea, except for contributions from northern rivers, where the levels of atmospheric NO3− are higher. An additional important source in the central Baltic Sea is N2 fixation by diazotrophs, which contributes 31–62% of the overall NO3− pool at this site. The results obtained with this method are in good agreement with source estimates based upon δ15N values in sediments and a three-dimensional ecosystem model, ERGOM. We suggest that this approach can be easily modified to determine NO3− sources in other marginal seas or larger near-coastal areas where NO3− is abundant in winter surface waters when fractionation processes are minor.


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