Roles of sulfate adsorption and base cation supply in controlling the chemical response of streams of western Virginia to reduced acid deposition

Decades of acid deposition across northeastern North America has caused excess leaching of soil base cations (Ca2+, Mg2+, K+) and increases in bioavailable aluminum (Al3+) that, in combination, have resulted in widespread decreases in potential forest productivity. Despite major reductions in SO2 and NOx emissions since the 1990s, forest soils across the region have shown few signs of recovery from acid deposition impacts and it could take decades or centuries for natural recovery to occur. As a result, affected forests are stressed, less productive, and more prone to climate change-induced damage. Helicopter liming of upland forests may be an effective way to jump-start the soil recovery process. Here we report on early results (one-year) from a helicopter liming trial in Nova Scotia, Canada where 10 tonnes/ha of dolomitic limestone was applied to approximately 8 ha of mature red spruce (Picea rubens) and mature tolerant hardwood (Acer spp. and Betula spp.) forest. Data are presented on (i) the effectiveness of helicopter liming in forests; (ii) the initial chemical response of forest floor organic and mineral soil horizons; and (iii) the initial chemical response of red spruce foliage, maple foliage, and ground vegetation. Preliminary results showed that despite non-uniform lime distribution, there were significant increases (P < 0.05) in Ca2+, Mg2+, pH, and base saturation (BS), and significant decreases in total acidity in forest floor organic horizons in both the mature red spruce and tolerant hardwood stands; however, there were no significant changes in Al3+. The initial chemical response in sugar maple and red spruce foliage showed significant increases in the Ca/Al molar ratio . &#160;The initial response in ground vegetation (Schreber&#8217;s moss; Pleurozium schreberi and wood fern; Dryopteris intermedia) showed significant increases in Ca2+ and decreases in K+ for both species; however, Schreber&#8217;s moss also showed significant increases in Mg2+ and Al3+ while wood fern did not. These early chemical results are promising and further support the use of helicopter liming as an effective tool to combat lingering effects from acid deposition in acidified forests.

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Acid deposition induced base cation loss and different responses of soils and sediments in Taihu Lake watershed, China

Chemosphere ◽

10.1016/j.chemosphere.2019.03.136 ◽

2019 ◽

Vol 226 ◽

pp. 149-158

Author(s):

Dai Dan ◽

Yu Tao ◽

Deng Yixiang ◽

Sun Fuhong ◽

Zhao Jian ◽

...

Keyword(s):

Acid Deposition ◽

Taihu Lake ◽

Base Cation ◽

Soils And Sediments

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The role of Athyrium distentifolium in reduction of soil acidification and base cation losses due to acid deposition in a deforested mountain area

Plant and Soil ◽

10.1007/s11104-011-1048-8 ◽

2011 ◽

Vol 354 (1-2) ◽

pp. 107-120 ◽

Cited By ~ 5

Author(s):

Ivan Tůma ◽

Karel Fiala ◽

Jaroslav Záhora ◽

Petr Holub

Keyword(s):

Acid Deposition ◽

Soil Acidification ◽

Base Cation ◽

Mountain Area

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Impacts of uncertainties in base‐cation deposition on the assessment of critical loads for acid deposition

Journal of Environmental Science and Health Part A ◽

10.1080/10934520009377086 ◽

2000 ◽

Vol 35 (10) ◽

pp. 1915-1921 ◽

Cited By ~ 1

Author(s):

Junling An ◽

Meiyuan Huang

Keyword(s):

Acid Deposition ◽

Critical Loads ◽

Base Cation

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The impact of acid deposition and forest harvesting on lakes and their forested catchments in south central Ontario: a critical loads approach

Hydrology and Earth System Sciences ◽

10.5194/hess-6-833-2002 ◽

2002 ◽

Vol 6 (5) ◽

pp. 833-848 ◽

Cited By ~ 14

Author(s):

S. A. Watmough ◽

P. J. Dillon

Keyword(s):

Acid Deposition ◽

Forest Soils ◽

Critical Loads ◽

Base Cation ◽

Forest Harvesting ◽

Case Scenario ◽

Forested Catchments ◽

South Central ◽

The Impact ◽

Sswc Model

Abstract. The impact of acid deposition and tree harvesting on three lakes and their representative sub-catchments in the Muskoka-Haliburton region of south-central Ontario was assessed using a critical loads approach. As nitrogen dynamics in forest soils are complex and poorly understood, for simplicity and to allow comparison among lakes and their catchments, CLs (A) for both lakes and forest soils were calculated assuming that nitrate leaching from catchments will not change over time (i.e. a best case scenario). In addition, because soils in the region are shallow, base cation weathering rates for the representative sub-catchments were calculated for the entire soil profile and these estimates were also used to calculate critical loads for the lakes. These results were compared with critical loads obtained by the Steady State Water Chemistry (SSWC) model. Using the SSWC model, critical loads for lakes were between 7 and 19 meq m-2yr-1 higher than those obtained from soil measurements. Lakes and forests are much more sensitive to acid deposition if forests are harvested, but two acid-sensitive lakes had much lower critical loads than their respective forested sub-catchments implying that acceptable acid deposition levels should be dictated by the most acid-sensitive lakes in the region. Under conditions that assume harvesting, the CL (A) is exceeded at two of the three lakes and five of the six sub-catchments assessed in this study. However, sulphate export from catchments greatly exceeds input in bulk deposition and, to prevent lakes from falling below the critical chemical limit, sulphate inputs to lakes must be reduced by between 37% and 92% if forests are harvested. Similarly, sulphate leaching from forested catchments that are harvested must be reduced by between 16 and 79% to prevent the ANC of water draining the rooting zone from falling below 0 μeq l-1. These calculations assume that extremely low calcium leaching losses (9–27 μeq l-1) from forest soils can be maintained without any decrease in forest productivity. Calcium concentrations in the three lakes have decreased by between ∼10 and 25% over the past 20 years and calculations assume that calcium concentrations in lakes can fall to around 30% of their current values without any harmful effects on biota. Both these assumptions require urgent investigation. Keywords: acid deposition, calcium, critical loads, forests, harvesting, lakes

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Forest Soil Cation Dynamics and Increases in Carbon on the Allegheny Plateau, PA, USA Following a Period of Strongly Declining Acid Deposition

Soil Systems ◽

10.3390/soilsystems5010016 ◽

2021 ◽

Vol 5 (1) ◽

pp. 16

Author(s):

Scott W. Bailey ◽

Robert P. Long ◽

Stephen B. Horsley

Keyword(s):

Organic Matter ◽

Acid Deposition ◽

Mineral Soil ◽

Base Cation ◽

Partial Recovery ◽

Exchangeable Calcium ◽

Exchangeable Aluminum ◽

Repeated Sampling ◽

Calcium And Magnesium ◽

Allegheny Plateau

Reductions in exchangeable calcium and magnesium and increase in exchangeable aluminum concentrations have been shown in soils impacted by acid deposition, including at four sites on the Allegheny Plateau, PA, USA, sampled in 1967 and 1997 during a period of peak deposition. We repeated sampling at these sites in 2017 to evaluate changes in soils during the more recent period when there has been a strong decline in acid deposition. The uppermost horizons, including the Oa and A horizons where humified organic matter transitions to mineral soil, were thicker, had higher concentrations of organic carbon and exchangeable calcium and magnesium, and lower concentrations of exchangeable aluminum in 2017 compared to 1997, approximating values measured in 1967. Below the Oa/A horizons, 2017 soil chemistry was more similar to the 1997 results, with some reduction of Ca in the recent measurements. These results suggest recovery of base cation–aluminum balance in surface horizons and may indicate a reduction of aluminum mobilization and increased efficiency of vegetation recycling of nutrients with decreased acid anion concentrations. These changes are consistent with a partial recovery from acid deposition. However, the increase in humified soil organic matter may also be affected by coincident increases in temperature and soil moisture.

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Effects of decreasing acid deposition and climate change on acid extremes in an upland stream

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-4-2901-2007 ◽

2007 ◽

Vol 4 (5) ◽

pp. 2901-2944 ◽

Cited By ~ 7

Author(s):

C. D. Evans ◽

B. Reynolds ◽

C. Hinton ◽

S. Hughes ◽

D. Norris ◽

...

Keyword(s):

Climate Change ◽

Acid Deposition ◽

Base Cation ◽

High Flow ◽

Sea Salt ◽

Chemical Recovery ◽

Organic Soils ◽

Mean Flow ◽

Acid Episodes

Abstract. This study assesses the major chemical processes leading to acid extremes in a small, moorland stream in mid-Wales, UK, which has been monitored since 1979. Results suggest that base cation (mainly calcium) dilution, the "sea-salt effect", and elevated nitrate pulses, are the major causes of seasonal/episodic minima in acid neutralising capacity (ANC), and that the relative importance of these drivers has remained approximately constant during 25 years of decreasing acid deposition and associated long-term chemical recovery. Many of the chemical variations causing short-term reductions in stream acidity, particularly base cation dilution and organic acid increases, are closely related to changes in water-flowpath and therefore to stream discharge. Changes in the observed pH-discharge relationship over time indicate that high-flow pH has increased more rapidly than mean-flow pH, and therefore that episodes have decreased in magnitude since 1980. However a two-box application of the dynamic model MAGIC, whilst reproducing this trend, suggests that it will not persist in the long term, with mean ANC continuing to increase until 2100, but the ANC of the upper soil (the source of relatively acid water during high-flow episodes) stabilising close to zero beyond 2030. With climate change predicted to lead to an increase in maximum flows in the latter half of the century, high-flow related acid episodes may actually become more rather than less severe in the long term, although the model suggests that this effect may be small. Two other predicted climatic changes could also detrimentally impact on acid episodes: increased severity of winter "sea-salt" episodes due to higher wind speeds during winter storms; and larger sulphate pulses due to oxidation of reduced sulphur held in organic soils, during more extreme summer droughts. At the Gwy, the near-coastal location and relatively small extent of peat soils suggest that sea-salt episodes may have the greatest influence.

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