Timothy J. Sullivan
Oregon State University
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Water Resources Research | 1994
Charles T. Driscoll; Michael D. Lehtinen; Timothy J. Sullivan
Data from the large and diverse Adirondack Lake Survey were used to calibrate four simple organic acid analog models in an effort to quantify the influence of naturally occurring organic acids on lake water pH and acid-neutralizing capacity (ANC). The organic acid analog models were calibrated to observations of pH, dissolved organic carbon (DOC), and organic anion (An−) concentrations from a reduced data set representing 1128 individual lake samples, expressed as 41 observations of mean pH, in intervals of 0.1 pH units from pH 3.9 to 7.0. Of the four organic analog approaches examined, including the Oliver et al. (1983) model, as well as monoprotic, diprotic, and triprotic representations, the triprotic analog model yielded the best fit (r2 = 0.92) to the observed data. Moreover, the triprotic model was qualitatively consistent with observed patterns of change in organic solute charge density as a function of pH. A low calibrated value for the first H+ dissociation constant (pKal = 2.62) and the observation that organic anion concentrations were significant even at very low pH (<4) indicate that naturally occurring organic solutes in these waters have strongly acidic functional groups. Inclusion of organic acidity in model calculations resulted in good agreement between measured and predicted values of lake water pH and ANC. Assessments to project the response of surface waters to future changes in atmospheric deposition, through the use of acidification models, will need to include representations of organic acids in model structure to make accurate predictions of pH and ANC.
Frontiers in Ecology and the Environment | 2012
Tara L. Greaver; Timothy J. Sullivan; Jeffrey D. Herrick; Mary Barber; Jill S. Baron; B. J. Cosby; Marion E Deerhake; Robin L. Dennis; Jean-Jacques Dubois; Christine L. Goodale; Alan T. Herlihy; Gregory B. Lawrence; Lingli Liu; Jason A. Lynch; Kristopher Novak
Four decades after the passage of the US Clean Air Act, air-quality standards are set to protect ecosystems from damage caused by gas-phase nitrogen (N) and sulfur (S) compounds, but not from the deposition of these air pollutants to land and water. Here, we synthesize recent scientific literature on the ecological effects of N and S air pollution in the US. Deposition of N and S is the main driver of ecosystem acidification and contributes to nutrient enrichment in many natural systems. Although surface-water acidification has decreased in the US since 1990, it remains a problem in many regions. Perturbations to ecosystems caused by the nutrient effects of N deposition continue to emerge, although gas-phase concentrations are generally not high enough to cause phytotoxicity. In all, there is overwhelming evidence of a broad range of damaging effects to ecosystems in the US under current air-quality conditions.
Environmental Science & Technology | 2013
Timothy J. Sullivan; Gregory B. Lawrence; Scott W. Bailey; Todd C. McDonnell; Colin M. Beier; Kathleen C. Weathers; G.T. McPherson; Daniel A. Bishop
We documented the effects of acidic atmospheric deposition and soil acidification on the canopy health, basal area increment, and regeneration of sugar maple (SM) trees across the Adirondack region of New York State, in the northeastern United States, where SM are plentiful but not well studied and where widespread depletion of soil calcium (Ca) has been documented. Sugar maple is a dominant canopy species in the Adirondack Mountain ecoregion, and it has a high demand for Ca. Trees in this region growing on soils with poor acid-base chemistry (low exchangeable Ca and % base saturation [BS]) that receive relatively high levels of atmospheric sulfur and nitrogen deposition exhibited a near absence of SM seedling regeneration and lower crown vigor compared with study plots with relatively high exchangeable Ca and BS and lower levels of acidic deposition. Basal area increment averaged over the 20th century was correlated (p < 0.1) with acid-base chemistry of the Oa, A, and upper B soil horizons. A lack of Adirondack SM regeneration, reduced canopy condition, and possibly decreased basal area growth over recent decades are associated with low concentrations of nutrient base cations in this region that has undergone soil Ca depletion from acidic deposition.
Archive | 1991
Rudolf B. Husar; Timothy J. Sullivan; Donald F. Charles
This chapter presents historical sulfur emission and deposition trends for regions in the United States and describes methods for assessing changes in water chemistry based on current spatial patterns, ion ratios and empirical models, and paleolimnological approaches. Reconstruction of sulfur deposition trends shows that current deposition to case study regions ranges from a factor of about 1 (Upper Midwest) to a factor of 10 (Catskills) above natural background. Deposition in the Northeast was high during the 1920s, 1940s, and 1960s, and has declined significantly since 1970. Sulfur deposition in the Southeast was low before the 1950s, but has increased significantly since then. Change in surface water chemistry can be assessed using simple empirical models, ion ratios, and analysis of current spatial patterns of chemistry. Many assumptions are implicit in these methods, so results should be interpreted carefully. Paleolimnological reconstructions of chemistry and biota from lake sediment records provide more direct evidence of past change than other approaches. Quantitative analyses of diatom and chrysophyte assemblages can be used to reconstruct past lakewater pH with a mean standard error of about ± 0.25 pH units.
Water Air and Soil Pollution | 1996
Timothy J. Sullivan; B. J. Cosby; Charles T. Driscoll; Donald F. Charles; H. F. Hemonds
We employed three mathematical models to make quantitative estimates of the pH of 33 statistically-selected lakes in the Adirondack mountains, New York (USA) prior to the Industrial Revolution (1840). The models included 1) the MAGIC watershed acidification model, 2) a paleolimnological model of diatom-inferred pH, and 3) the MAGIC model modified to incorporate an empirically-based model of natural organic acidity. Application of approaches 2) and 3) yielded consistent estimates of pre-industrial Adirondack lakewater pH. However, when the organic acid model was not included, MAGIC calculations and diatom-inferred values showed poor agreement. MAGIC projections of lakewater pH 50 years into the future, under differing atmospheric deposition scenarios, were also sensitive to inclusion of the organic acid model. MAGIC predicted greater recovery in response to reduced deposition when organic acids were not considered. These results suggest that failure to consider the pH buffering of naturally-occurring organic acidity will often result in biased projections which overemphasize the response of lakewater pH to changes in atmospheric inputs of strong acid.
Water Air and Soil Pollution | 1997
Timothy J. Sullivan; J. M. Eilers; B. J. Cosby; Kellie B. Vaché
Assessments of the aquatic effects of acidic deposition have focused on sulfur, as have recent efforts to control the emissions of acidifying compounds. Nitrogen dynamics were excluded from most acidic deposition modeling studies because it was believed that terrestrial ecosystems strongly retain N and because modeling N is a more formidable task than modeling S due to the influence of complex biological processes on N cycling. Re-examination of available data for the Adirondack Mountains of New York suggests that N deposition may be contributing to both chronic and episodic acidification of freshwaters to a greater extent than is generally believed. Previous research concluded that N has played a limited role in acidification processes in these lakes, based on regional averages of chronic chemistry. However, it is now known that historic acidification responses have been spatially variable within the Adirondack Mountains and that the declines in lakewater pH have been less than previously believed. Lakewater NO3− concentrations are commonly in the range of 5 to 25 μeq L−1 on a chronic basis in portions of the Adirondack region that have experienced significant chronic acidification. These NO3− concentrations correspond in magnitude to inferred historical acidification. Furthermore, the relative importance of NO3− as an agent of acidification increases dramatically during snowmelt when conditions are most toxic to fish. The consequence of not addressing N in formulating acidification recovery strategies for the Adirondacks includes the likelihood that we will overestimate the response of surface water to the mandated sulfur emissions reductions.
Ecological Applications | 2008
Brenden E. McNeil; Jane M. Read; Timothy J. Sullivan; Todd C. McDonnell; Ivan J. Fernandez; Charles T. Driscoll
Maps of canopy nitrogen obtained through analysis of high-resolution, hyperspectral, remotely sensed images now offer a powerful means to make landscape-scale to regional-scale estimates of forest N cycling and net primary production (NPP). Moreover, recent research has suggested that the spatial variability within maps of canopy N may be driven by environmental gradients in such features as historic forest disturbance, temperature, species composition, moisture, geology, and atmospheric N deposition. Using the wide variation in these six features found within the diverse forest ecosystems of the 2.5 million ha Adirondack Park, New York, USA, we examined linkages among environmental gradients and three measures of N cycling collected during the 2003 growing season: (1) field survey of canopy N, (2) field survey of soil C:N, and (3) canopy N measured through analysis of two 185 x 7.5 km Hyperion hyperspectral images. These three measures of N cycling strongly related to forest type but related poorly to all other environmental gradients. Further analysis revealed that the spatial pattern in N cycling appears to have distinct inter- and intraspecific components of variability. The interspecific component, or the proportional contribution of species functional traits to canopy biomass, explained 93% of spatial variability within the field canopy N survey and 37% of variability within the soil C:N survey. Residual analysis revealed that N deposition accounted for an additional 2% of variability in soil C:N, and N deposition and historical forest disturbance accounted for an additional 2.8% of variability in canopy N. Given our finding that 95.8% of the variability in the field canopy N survey could be attributed to variation in the physical environment, our research suggests that remotely sensed maps of canopy N may be useful not only to assess the spatial variability in N cycling and NPP, but also to unravel the relative importance of their multiple controlling factors.
Environmental Science & Technology | 1988
Timothy J. Sullivan; Charles T. Driscoll; Joseph M. Eilers; Dixon H. Landers
Input of neutral salt (NaCl) from sea spray, followed by Na{sup +}-H{sup +} exchange within the soil exchange complex, has been proposed as an important factor in surface water acidification of coastal areas. This hypothesis was tested on a regional basis by comparing the Na:Cl ratio of lake water with that of precipitation for the coastal lakes included in the US Environmental Protection Agency Eastern Lake Survey-I in New England. The precipitation Na:Cl ratio closely approximated that of seawater at monitoring stations located within approximately 20 km of the coast. Few lakes in this coastal region exhibited a Na:Cl ratio less than that observed in precipitation. Those lakes that were acidic (ANC {<=} 0) showed no tendency toward a lowered Na:Cl ratio. Sodium contribution from, rather than retention by, watershed soils was suggested by the data from these lakes. Although episodic acidification of runoff due to NaCl deposition may occur, there is little support for the neutral salt effect being an important long-term acidifying process in Northeastern lakes.
Water Air and Soil Pollution | 1998
Timothy J. Sullivan; B. J. Cosby
Although the increased mobilization of aluminum from soils to surface waters is widely recognized as one of the most important ecological effects of acidic deposition, lumped-parameter mathematical models of acidification response typically overestimate the change in Al concentration under changing deposition by a considerable margin. The assumption of equilibrium with gibbsite (Al(OH)3) in the MAGIC model and other models of acid-base chemistry is shown to be inconsistent with measured values for a large variety of lake and stream databases. A modified algorithm for predicting Al concentration, based on empirical relationships evident in field data, provided superior estimates of changes in Al concentration in three long-term monitoring data sets and under experimental conditions at two experimental watershed manipulation sites.
Environmental Science & Technology | 2010
Sandra A. Nierzwicki-Bauer; Charles W. Boylen; Lawrence W. Eichler; James P. Harrison; James W. Sutherland; William H. Shaw; Robert A. Daniels; Donald F. Charles; Frank W. Acker; Timothy J. Sullivan; Bahram Momen; Paul A. Bukaveckas
The Adirondack Mountains in New York State have a varied surficial geology and chemically diverse surface waters that are among the most impacted by acid deposition in the U.S. No single Adirondack investigation has been comprehensive in defining the effects of acidification on species diversity, from bacteria through fish, essential for understanding the full impact of acidification on biota. Baseline midsummer chemistry and community composition are presented for a group of chemically diverse Adirondack lakes. Species richness of all trophic levels except bacteria is significantly correlated with lake acid-base chemistry. The loss of taxa observed per unit pH was similar: bacterial genera (2.50), bacterial classes (1.43), phytoplankton (3.97), rotifers (3.56), crustaceans (1.75), macrophytes (3.96), and fish (3.72). Specific pH criteria were applied to the communities to define and identify acid-tolerant (pH<5.0), acid-resistant (pH 5.0-5.6), and acid-sensitive (pH>5.6) species which could serve as indicators. Acid-tolerant and acid-sensitive categories are at end-points along the pH scale, significantly different at P<0.05; the acid-resistant category is the range of pH between these end-points, where community changes continually occur as the ecosystem moves in one direction or another. The biota acid tolerance classification (batc) system described herein provides a clear distinction between the taxonomic groups identified in these subcategories and can be used to evaluate the impact of acid deposition on different trophic levels of biological communities.