Relative Importance of Anthropogenic versus Natural Sources of Acidity in Lakes and Streams of Central Ontario

1984 ◽  
Vol 41 (11) ◽  
pp. 1664-1677 ◽  
Author(s):  
Bruce D. LaZerte ◽  
Peter J. Dillon
Keyword(s):  
Acid Deposition ◽  
Surface Waters ◽  
Acidic Deposition ◽  
Alternative Hypothesis ◽  
Strong Acid ◽  
Anthropogenic Emissions ◽  
Sea Salts ◽  
High Discharge ◽  
Lake Acidity ◽  
Alternative Sources

Anthropogenic acid deposition has been implicated in the acidification of surface waters of central Ontario and elsewhere. However, alternative sources of acidity have been proposed, including (i) the release of protons and their accompanying acid anions by soils (e.g. organic acids) and (ii) the exchange of internally generated protons for the cations of atmospherically deposited neutral salts (e.g. sea salts). We show that for a typical acidified catchment in central Ontario the first hypothesis is not important during periods of high discharge or on an annual basis. As most of the neutral salts deposited on inland areas are sulphate and nitrate of anthropogenic origin, any acidity generated via the second mechanism can be reduced by reducing the emission of the salts. A third and alternative hypothesis is that deposition of strong acid alters only the balance between humic anions and sulphate in runoff waters, but not pH; we have shown this to be incorrect using catchments from the Sudbury region of Ontario where rates of acid deposition have recently declined. We conclude that in central Ontario, acidic deposition derived from anthropogenic SO2 sources is the primary causal factor in recent lake acidification, and that a reduction in the anthropogenic emissions affecting this area will result in a decrease in lake acidity.

Identifying Sources of Sulfate Aerosols Reaching Whiteface Mountain, NY

1985 ◽  
Vol 43 ◽  
pp. 98-101
Author(s):  
James S. Webber
Keyword(s):  
Trace Metals ◽  
Acid Deposition ◽  
Surface Waters ◽  
Dry Deposition ◽  
Coal Combustion ◽  
Public Awareness ◽  
Sulfate Aerosols ◽  
Wet And Dry Deposition ◽  
Whiteface Mountain ◽  
Toxic Trace Metals

INTRODUCTION“Acid rain” and “acid deposition” are terms no longer confined to the lexicon of atmospheric scientists and 1imnologists. Public awareness of and concern over this phenomenon, particularly as it affects acid-sensitive regions of North America, have increased dramatically in the last five years. Temperate ecosystems are suffering from decreased pH caused by acid deposition. Human health may be directly affected by respirable sulfates and by the increased solubility of toxic trace metals in acidified waters. Even man's monuments are deteriorating as airborne acids etch metal and stone features.Sulfates account for about two thirds of airborne acids with wet and dry deposition contributing equally to acids reaching surface waters or ground. The industrial Midwest is widely assumed to be the source of most sulfates reaching the acid-sensitive Northeast since S02 emitted as a byproduct of coal combustion in the Midwest dwarfs S02 emitted from all sources in the Northeast.

Chemical recovery and browning of Nova Scotia surface waters in response to declining acid deposition

2021 ◽  
Author(s):  
D. Redden ◽  
B. F. Trueman ◽  
D. W. Dunnington ◽  
L. E. Anderson ◽  
G. A. Gagnon
Keyword(s):  
Nova Scotia ◽  
Acid Deposition ◽  
Surface Waters ◽  
Chemical Recovery ◽  
Size Distributions ◽  
Iron Aluminum

Colour, pH, iron, and aluminum are increasing in NS surface waters; iron/aluminum size distributions include at least two colloidal fractions.

scholarly journals Reversibility of acidification: soils and surface waters

1990 ◽  
Vol 97 ◽  
pp. 169-191 ◽  
Author(s):  
Richard F. Wright ◽  
Michael Hauhs
Keyword(s):  
Surface Waters ◽  
Predictive Models ◽  
Large Scale ◽  
Acidic Deposition ◽  
Nitrogen Saturation ◽  
Future Climate Change ◽  
Water Acidification ◽  
Catchment Scale ◽  
Empirical Relationships

SynopsisAs empirical relationships between acidic deposition and its effects on soils and surface waters have become increasingly understood, the focus of attention has shifted to the reversal of acidification in response to decreased amounts of acidic deposition.Recent decreases in acidic deposition, in both North America and parts of Europe, have initiated the reversal of acidification and the recovery of impacted ecosystems. Reversal has also been investigated in large-scale experiments with whole ecosystems. Predictive models can account for much of this empirical and experimental data, at least at the catchment scale, over periods of years.Discrepancies between observed and predicted effects are attributable in part to the increasingly important role of nitrogen in soil and water acidification. ‘Nitrogen saturation’ threatens to offset the incipient recovery following decreases in SO2 emissions. Future climate change might further exacerbate the problem by increasing the rate of mineralisation of soil organic matter and releasing stored nitrogen.

RAIN Project: Results after 8 Years of Experimentally Reduced Acid Deposition to a Whole Catchment

1993 ◽  
Vol 50 (2) ◽  
pp. 258-268 ◽  
Author(s):  
Richard F. Wright ◽  
Erik Lotse ◽  
Arne Semb
Keyword(s):  
Acid Deposition ◽  
Soil Chemistry ◽  
Nitrogen Saturation ◽  
Base Cations ◽  
Strong Acid ◽  
Catchment Scale ◽  
Exclusion Experiment ◽  
Surface Water Chemistry ◽  
Southern Norway

At Risdalsheia (southern Norway), an ongoing catchment-scale acid-exclusion experiment has been conducted since 1984 as part of the RAIN project (Reversing Acidification In Norway). Acid precipitation is collected on a 1200-m2 transparent roof, treated by ion exchange, sea salts readded, and reapplied as clean rain beneath the roof Up to 1990 annual surveys of soil chemistry have revealed no significant trends. The chemical composition of runoff has changed: sulfate decreased from about 111 μeq/L in 1984 to 38 μeq/L in 1992 and nitrate from about 33 to 5 μeq/L. Base cations decreased and alkalinity increased over the 8-yr period from −88 to −29 μeq/L to compensate for this change in strong acid anions. Much of the alkalinity change is due to the increased role of organic anions. The results fit an empirical nomograph relating alkalinity, base cations, and strong acid anions and a new empirical nomograph relating alkalinity, H+, and total organic carbon. The acid-exclusion experiment provides the first catchment-scale evidence for the reversibility of nitrogen saturation; RAIN results corroborate field observations of changes in surface water chemistry in response to reduced acid deposition as well as process-oriented, conceptual acidification models.

scholarly journals MICS-Asia III: Overview of model inter-comparison and evaluation of acid deposition over Asia

2019 ◽  
Author(s):  
Syuichi Itahashi ◽  
Baozhu Ge ◽  
Keiichi Sato ◽  
Joshua S. Fu ◽  
Xuemei Wang ◽  
...  
Keyword(s):  
Acid Deposition ◽  
Phase Ii ◽  
Wet Deposition ◽  
Lessons Learned ◽  
Phase Iii ◽  
Anthropogenic Emissions ◽  
Observation Data ◽  
Total Deposition ◽  
North Asia ◽  
Phase Iii Study

Abstract. The Model Inter-Comparison Study for Asia (MICS-Asia) Phase III was conducted to promote understanding of regional air quality and climate change in Asia, which have received growing attention due to the huge amount of anthropogenic emissions worldwide. This study provides an overview of acid depositions. Specifically, dry and wet depositions of the following species were analyzed: S (sulfate aerosol, sulfur dioxide (SO2), and sulfuric acid (H2SO4)), N (nitrate aerosol, nitrogen monoxide (NO), nitrogen dioxide (NO2), and nitric acid (HNO3)), and A (ammonium aerosol and ammonia (NH3)). The wet deposition simulated by a total of nine models was analyzed and evaluated using ground observation data from the Acid Deposition Monitoring Network in East Asia (EANET). In this Phase III study, the number of observation sites was increased to 54 from 37 in the Phase II study, and Southeast Asian countries were newly added. Additionally, whereas the analysis period was limited to representative months of each season in MICS-Asia Phase II, this Phase III study analyzed the full year of 2010. The scope of this overview mainly focuses on the annual accumulated depositions. In general, models can capture the observed wet depositions over Asia but underestimate the wet deposition of S and A and show large differences in the wet deposition of N. Furthermore, the ratio of wet deposition to the total deposition (the sum of dry and wet deposition) was investigated in order to understand the role of important processes in the total deposition. The general dominance of wet deposition over Asia and attributions from dry deposition over land were consistently found in all models. Then, total deposition maps over 13 countries participating in EANET were produced, and the balance between deposition and anthropogenic emissions was calculated. Excesses of deposition, rather than of anthropogenic emissions, were found over Japan, North Asia, and Southeast Asia, indicating the possibility of long-range transport within and outside Asia, as well as other emission sources. To improve the ability of models to capture the observed wet deposition, two approaches were attempted, namely, ensemble and precipitation adjustment. The ensemble approach was effective at modulating the differences in performance among models, and the precipitation-adjusted approach demonstrated that the model performance for precipitation played a key role in better simulating wet deposition. Finally, the lessons learned from this Phase III study and future perspectives for Phase IV are summarized.

scholarly journals Hydrogeochemsitry of montane springs and their influence on streams in the Cairngorm mountains, Scotland

1999 ◽  
Vol 3 (3) ◽  
pp. 409-419 ◽  
Author(s):  
C. Soulsby ◽  
R. Malcolm ◽  
R. Helliwell ◽  
R.C. Ferrier
Keyword(s):  
High Altitude ◽  
Surface Waters ◽  
Environmental Changes ◽  
Seasonal Pattern ◽  
Ionic Composition ◽  
Spring Water ◽  
Residence Times ◽  
Sea Salts ◽  
Fractured Bedrock ◽  
Catchment Areas

Abstract. Springs are important groundwater discharge points on the high altitude (>800m) plateaux of the Cairngorm mountains, Scotland and form important wetland habitats within what is often a dry, sub-arctic landscape. The hydrogeochemistry of a typical spring in the Allt a'Mharcaidh catchment was examined between 1995-98 in order to characterise its chemical composition, identify the dominant controls on its chemical evolution and estimate groundwater residence time using 18O isotopes. Spring water, sustained by groundwater flow in shallow drift deposits and fractured bedrock, was moderately acidic (mean pH 5.89), with a very low alkalinity (mean 18 μeq l-1) and the ionic composition was dominated by sea-salts derived from atmospheric sources. Geochemical modelling using NETPATH, predicted that the dissolution of plagioclase mainly controls the release of Si, non-marine Na, Ca, K and Al into spring water. Hydrological conditions influenced seasonal variations in spring chemistry, with snowmelt associated with more rapid groundwater flows and lower weathering rates than summer discharges. Downstream of the spring, the chemistry of surface water was fundamentally different as a result of drainage from larger catchment areas, with increased soil and drift cover, and higher evaporation rates. Thus, the hydrogeochemical influence of springs on surface waters appears to be localized. Mean δ18O values in spring water were lower and more damped than those in precipitation. Nevertheless, a sinusoidal seasonal pattern was observed and used to estimate mean residence times of groundwater of around 2 years. Thus, in the high altitude plateau of the Cairngorms, shallow, coarse drift deposits from significant aquifers. At lower altitudes, deeper drift deposits, combined with larger catchment areas, increase mean groundwater residence times to >5 years. At high altitudes, the shallow, permeable nature of the drifts dictates that groundwater is vulnerable to impacts of environmental changes that could be usefully monitored at spring sites.

scholarly journals Spatial distribution and seasonal variations of atmospheric sulfur deposition over Northern China

2012 ◽  
Vol 12 (9) ◽  
pp. 23645-23677 ◽  
Author(s):  
Y. P. Pan ◽  
Y. S. Wang ◽  
G. Q. Tang ◽  
D. Wu
Keyword(s):  
Acid Deposition ◽  
Seasonal Variations ◽  
Dry Deposition ◽  
Wet Deposition ◽  
Northern China ◽  
Anthropogenic Emissions ◽  
Deposition Flux ◽  
Natural Ecosystems ◽  
Total Acid ◽  
S Deposition

Abstract. The increasing anthropogenic emissions of acidic compounds have induced acid deposition accompanied by acidification in the aquatic and terrestrial ecosystems worldwide. However, comprehensive assessment of spatial patterns and long-term trends of acid deposition in China remains a challenge due to a paucity of field-based measurement data, in particular for dry deposition. Here we quantify the sulfur (S) deposition on a regional scale via precipitation, particles and gases during a 3-yr observation campaign at ten selected sites in Northern China. Results show that the total S deposition flux in the target area ranged from 35.0 to 100.7 kg S ha−1 yr−1, categorized as high levels compared to those documented in Europe, North America, and East Asia. The ten-site, 3-yr average total S deposition was 64.8 kg S ha−1 yr−1, with 32% attributed to wet deposition, and the rest attributed to dry deposition. Compared with particulate sulfate, gaseous SO2 was the major contributor of dry-deposited S, contributing approximately 49% to the total flux. Wet deposition of sulfate showed pronounced seasonal variations with maximum in summer and minimum in winter, corresponding to precipitation patterns in Northern China. However, the spatial and inter-annual differences in the wet deposition were not significant, which were influenced by the precipitation amount, scavenging ratio and the concentrations of atmospheric S compounds. In contrast, the relatively large dry deposition of SO2 and sulfate during cold season, especially at industrial areas, was reasonably related to the local emissions from home heating. Although seasonal fluctuations were constant, clear spatial differences were observed in the total S deposition flux and higher values were also found in industrial areas with huge emissions of SO2. These findings indicate that human activity has dramatically altered the atmospheric S deposition and thus regional S cycles. To systematically illustrate the potential effects of acidifying deposition on the receiving environment, we calculated the deposition of "potential acidity" that takes into account the microbial transformation of ammonium to nitrate in the ecosystems, resulting in the release of hydrogen ions. The estimated total "acid equivalents" deposition of S and nitrogen (N) fell within the range of 4.2–11.6 keq ha−1 yr−1, with a ten-site, 3-yr mean of 8.4 keq ha−1 yr−1. This value is significantly higher than that of other regions in the world and exceeds the critical loads for natural ecosystems in Northern China, thus prompting concerns regarding ecological impacts. The contribution of S to total acid deposition was comparable to that of N at most of sites; however, the importance of S on acidification risks was more pronounced in the industrial sites, highlighting that further SO2 abatement from industrial emissions is still needed. Taking these findings and our previous studies together, a multi-pollutant perspective and joint mitigate strategies to abate SO2 and NH3 simultaneously in the target areas are recommended to protect the natural ecosystems from excess acid deposition caused by anthropogenic emissions.

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