Adirondack Region Of New York Research Articles

Chemical and biological recovery from acid deposition within the Honnedaga Lake watershed, New York, USA

Honnedaga Lake in the Adirondack region of New York has sustained a heritage brook trout population despite decades of atmospheric acid deposition. Detrimental impacts from acid deposition were observed from 1920 to 1960 with the sequential loss of acid-sensitive fishes, leaving only brook trout extant in the lake. Open-lake trap net catches of brook trout declined for two decades into the late 1970s, when brook trout were considered extirpated from the lake but persisted in tributary refuges. Amendments to the Clean Air Act in 1990 mandated reductions in sulfate and nitrogen oxide emissions. By 2000, brook trout had re-colonized the lake coincident with reductions in surface-water sulfate, nitrate, and inorganic monomeric aluminum. No changes have been observed in surface-water acid-neutralizing capacity (ANC) or calcium concentration. Observed increases in chlorophyll a and decreases in water clarity reflect an increase in phytoplankton abundance. The zooplankton community exhibits low species richness, with a scarcity of acid-sensitive Daphnia and dominance by acid-tolerant copepods. Trap net surveys indicate that relative abundance of adult brook trout population has significantly increased since the 1970s. Brook trout are absent in 65% of tributaries that are chronically acidified with ANC of <0μeq/L and toxic aluminum levels (>2μmol/L). Given the current conditions, a slow recovery of chemistry and biota is expected in Honnedaga Lake and its tributaries. We are exploring the potential to accelerate the recovery of brook trout abundance in Honnedaga Lake through lime applications to chronically and episodically acidified tributaries.

Specific ultra-violet absorbance as an indicator of mercury sources in an Adirondack River basin

The Adirondack region of New York has been identified as a hot spot where high methylmercury concentrations are found in surface waters and biota, yet mercury (Hg) concentrations vary widely in this region. We collected stream and groundwater samples for Hg and organic carbon analyses across the upper Hudson River, a 493 km2 basin in the central Adirondacks to evaluate and model the sources of variation in filtered total Hg (FTHg) concentrations. Variability in FTHg concentrations during the growing seasons (May–Oct) of 2007–2009 in Fishing Brook, a 66-km2 sub-basin, was better explained by specific ultra-violet absorbance at 254 nm (SUVA254), a measure of organic carbon aromaticity, than by dissolved organic carbon (DOC) concentrations, a commonly used Hg indicator. SUVA254 was a stronger predictor of FTHg concentrations during the growing season than during the dormant season. Multiple linear regression models that included SUVA254 values and DOC concentrations could explain 75 % of the variation in FTHg concentrations on an annual basis and 84 % during the growing season. A multiple linear regression landscape modeling approach applied to 27 synoptic sites across the upper Hudson basin found that higher SUVA254 values are associated with gentler slopes, and greater riparian area, and lower SUVA254 values are associated with an increasing influence of open water. We hypothesize that the strong Hg–SUVA254 relation in this basin reflects distinct patterns of FTHg and SUVA254 that are characteristic of source areas that control the mobilization of Hg to surface waters, and that the seasonal influence of these source areas varies in this heterogeneous basin landscape.

Long-term recovery of lakes in the Adirondack region of New York to decreases in acidic deposition

Abstract After years of adverse impacts to the acid-sensitive ecosystems of the eastern United States, the Acid Rain Program and Nitrogen Budget Program were developed to control sulfur dioxide (SO2) and nitrogen oxide (NOx) emissions through market-based cap and trade systems. We used data from the National Atmospheric Deposition Program’s National Trends Network (NTN) and the U.S. EPA Temporally Integrated Monitoring of Ecosystems (TIME) program to evaluate the response of lake-watersheds in the Adirondack region of New York to changes in emissions of sulfur dioxide and nitrogen oxides resulting from the Acid Rain Program and the Nitrogen Budget Program. TIME is a long-term monitoring program designed to sample statistically selected subpopulations of lakes and streams across the eastern U.S. to quantify regional trends in surface water chemistry due to changes in atmospheric deposition. Decreases in wet sulfate deposition for the TIME lake-watersheds from 1991 to 2007 (−1.04 meq m−2-yr) generally corresponded with decreases in estimated lake sulfate flux (−1.46 ± 0.72 meq m−2-yr), suggesting declines in lake sulfate were largely driven by decreases in atmospheric deposition. Decreases in lake sulfate and to a lesser extent nitrate have generally coincided with increases in acid neutralizing capacity (ANC) resulting in shifts in lakes among ANC sensitivity classes. The percentage of acidic Adirondack lakes (ANC

Changes in the chemistry of acidified Adirondack streams from the early 1980s to 2008

Lakes in the Adirondack region of New York have partially recovered in response to declining deposition, but information on stream recovery is limited. Here we report results of Adirondack stream monitoring from the early 1980s to 2008. Despite a 50% reduction in atmospheric deposition of sulfur, overall increases in pH of only 0.28 and ANC of 13 μeq L−1 were observed in 12 streams over 23 years, although greater changes did occur in streams with lower initial ANC, as expected. In the North Tributary of Buck Creek with high dissolved organic carbon (DOC) concentrations, SO42− concentrations decreased from 1999 to 2008 at a rate of 2.0 μmol L−1 y−1, whereas in the neighboring South Tributary with low DOC concentrations, the decrease was only 0.73 μmol L−1 y−1. Ca2+ leaching decreased in the North Tributary due to the SO42− decrease, but this was partially offset by an increase in Ca2+ leaching from increased DOC concentrations.

A Comparison of the Temporally Integrated Monitoring of Ecosystems and Adirondack Long-Term Monitoring Programs in the Adirondack Mountain Region of New York

This paper compares lake chemistry in the Adirondack region of New York measured by the Temporally Integrated Monitoring of Ecosystems (TIME) and Adirondack Long-Term Monitoring (ALTM) programs by examining the data from six lakes common to both programs. Both programs were initiated in the early 1990s to track the efficacy of emission reduction policies and to assess the full impacts of acid deposition on surface water chemistry. They now serve to inform on the emerging chemical recovery of these waters. The Adirondack TIME program utilizes a probability-based approach to assess chronic acidification in a population of lakes using one summer sample per year. The ALTM attempts to track changes in both chronic and episodic acidification across a gradient of lake types using monthly samples. The ALTM project has two important attributes that contrast with the TIME program in the Adirondacks: higher temporal resolution (monthly versus once during the summer or fall) and speciation of aluminum. In particular, the ALTM program provides inorganic monomeric aluminum (AlIM), the fraction of Al that is most toxic. The monthly sampling of the ALTM program includes the spring snowmelt period when acid-neutralizing capacity and pH are near their lowest and Al levels are near their highest. We compare chemistry trends (1992–2008) for sulfate, nitrate, base cations, dissolved organic carbon, hydrogen ion, acid neutralizing capacity, and Al for the six lakes common to both programs. We also compare relatively high springtime AlIM concentrations from the ALTM with relatively low summertime total Al concentrations from the TIME, showing that the ALTM program provides a more biologically relevant indicator of the effects of acid deposition, illustrating the value of the complementary monitoring efforts in the Adirondack region.

Application of the PnET-BGC – An integrated biogeochemical model – To assess the surface water ANC recovery in the Adirondack region of New York under three multi-pollutant proposals

We applied an integrated biogeochemical model PnET-BGC to predict the response of acid neutralizing capacity (ANC) in lakes – a measure of the ability of water to neutralize inputs of strong acid – from 2001 to 2050 in the Adirondack region of New York, USA under three multi-pollutant proposal scenarios. Through model predictions, we assessed the impacts of these proposals on ecosystem recovery for research and policy initiatives. Our analysis indicated that the predicted recovery rates of surface water ANC obtained from the PnET-BGC model show low spatial autocorrelation. Predicted recovery rates are also closely related with the percentage of watershed areas of coniferous vegetation and deciduous vegetation, elevation and lake area, which turn out not to be significantly different from each other over the entire period of future scenarios (2001–2050). We applied a Geographic Weighted Regression model (GWR) to study the spatial patterns of predicted lake ANC in the Adirondacks through 2050 due to its high spatial autocorrelation. These results showed that lake depth and square of elevation can explain 40% of variation in the predicted ANC, which is 26% more variation than explained by the non-spatial Ordinary Least-Squares Regression (OLS). Our calculations also suggest that even under the Carper Bill, the most aggressive air pollutant control scenario considered, not all Adirondack lakes will recover (i.e., ANC > 50 μeq/L) from elevated acidic deposition by 2050. The research provides a basis for more informed emission controls and land use/land cover (LULC) policy-making in the north-eastern USA and elsewhere.

A Redescription of Catostomus utawana (Cypriniformes: Catostomidae)

We redescribe Catostomus utawana using specimens from an extant population and museum collections from the Adirondack region of New York and compare it to the widely distributed Catostomus commersonii. These species differ from each other in body depth, relative lengths of pectoral, anal, and pelvic fins, in the lengths of the dorsal-fin and anal-fin bases, and in several characteristics related to head shape and body depth. Catostomus utawana females in breeding condition have well-developed pearl organs on the anal fin, ventral lobe of the caudal fin, and on most of the scales found on the ventral half of the body posterior to the dorsal fin. Catostomus commersonii females in breeding condition usually lack pearl organs. Catostomus utawana males in breeding condition are extensively covered in pearl organs, whereas the pearl organs on C. commersonii males are typically limited to the anal and caudal fins, scales posterior to the dorsal fin, and on the head. Catostomus utawana males in breeding condition have a gold mid-lateral stripe and a gold patch above each eye; breeding females lack gold coloration. Catostomus utawana males and females lack red coloration throughout their spawning season. We propose using the common name of Summer Sucker for C. utawana.

Hierarchical models for estimating density from DNA mark–recapture studies

Genetic sampling is increasingly used as a tool by wildlife biologists and managers to estimate abundance and density of species. Typically, DNA is used to identify individuals captured in an array of traps (e.g., baited hair snares) from which individual encounter histories are derived. Standard methods for estimating the size of a closed population can be applied to such data. However, due to the movement of individuals on and off the trapping array during sampling, the area over which individuals are exposed to trapping is unknown, and so obtaining unbiased estimates of density has proved difficult. We propose a hierarchical spatial capture-recapture model which contains explicit models for the spatial point process governing the distribution of individuals and their exposure to (via movement) and detection by traps. Detection probability is modeled as a function of each individual's distance to the trap. We applied this model to a black bear (Ursus americanus) study conducted in 2006 using a hair-snare trap array in the Adirondack region of New York, USA. We estimated the density of bears to be 0.159 bears/km2, which is lower than the estimated density (0.410 bears/km2) based on standard closed population techniques. A Bayesian analysis of the model is fully implemented in the software program WinBUGS.

Factors influencing changes in mercury concentrations in lake water and yellow perch (Perca flavescens) in Adirondack lakes

Over the past 20+ years, fish with elevated concentrations of mercury (Hg) have been observed in remote lake districts, including the Adirondack region of New York. Across eastern North America studies have also reported a negative correlation between fish Hg concentration and lake pH. Recent controls in emissions of sulfur dioxide (SO2) have resulted in some improvement in the acid–base status of acid-impacted surface waters including Adirondack lakes. In addition, there has been an apparent decrease in atmospheric Hg deposition. A synoptic survey of 25 lakes in the Adirondacks was conducted in 1992–1993 to analyze spatial patterns of Hg in the water column and yellow perch (Perca flavescens). The same cluster of 25 lakes was resurveyed in 2005–2006 to evaluate if changes in lake concentrations of Hg species or fish Hg have occurred. We observed a varied response of changes in water chemistry and fish Hg concentrations. In twelve of the resurveyed lakes the yellow perch had lower Hg concentrations, six lakes had yellow perch with higher Hg concentrations, and in seven lakes yellow perch Hg concentrations did not change significantly (α = 0.05). Four variables appear to influence the change in yellow perch Hg concentrations in the Adirondacks: watershed area, elevation, change in pH, and change in fish body condition. We hypothesize that as the acidity in lakes is attenuated, the lakes may become more productive and/or water quality conditions less stressful to fish leading to increasing fish body condition. As fish body condition improves, fish exhibit “growth dilution” of tissue contaminants leading to lower fish Hg concentrations.

Chronic and Episodic Acidification of Adirondack Streams from Acid Rain in 2003–2005

Limited information is available on streams in the Adirondack region of New York, although streams are more prone to acidification than the more studied Adirondack lakes. A stream assessment was therefore undertaken in the Oswegatchie and Black River drainages; an area of 4585 km(2) in the western part of the Adirondack region. Acidification was evaluated with the newly developed base-cation surplus (BCS) and the conventional acid-neutralizing capacity by Gran titration (ANC(G)). During the survey when stream water was most acidic (March 2004), 105 of 188 streams (56%) were acidified based on the criterion of BCS < 0 microeq L(-1), whereas 29% were acidified based on an ANC(G) value < 0 microeq L(-1). During the survey when stream water was least acidic (August 2003), 15 of 129 streams (12%) were acidified based on the criterion of BCS < 0 microeq L(-1), whereas 5% were acidified based on ANC(G) value < 0 microeq L(-1). The contribution of acidic deposition to stream acidification was greater than that of strongly acidic organic acids in each of the surveys by factors ranging from approximately 2 to 5, but was greatest during spring snowmelt and least during elevated base flow in August. During snowmelt, the percentage attributable to acidic deposition was 81%, whereas during the October 2003 survey, when dissolved organic carbon (DOC) concentrations were highest, this percentage was 66%. The total length of stream reaches estimated to be prone to acidification was 718 km out of a total of 1237 km of stream reaches that were assessed.

Evaluation of Shifts in White‐Tailed Deer Winter Yards in the Adirondack Region of New York

ABSTRACT In the Adirondack region of northern New York, USA, severe weather and deep snow typically force white‐tailed deer (Odocoileus virginianus) to congregate in areas of dense coniferous cover and along watercourses at lower elevations. We examined 16 yards in the Adirondacks and explored the observation that deer have changed their movement behavior to incorporate residential communities within their wintering areas. We compared locations of deer herds in 2003 and 2004 to deer wintering areas mapped during the 1960s and 1970s. Deer were predominantly absent in 9 of 16 historical yards but were present in residential communities within the same drainage. Yarding areas to which deer shifted contained more residential, deciduous, and mixed cover than yards where no shift occurred, indicating that deer in residential areas were using conifer and mixed cover at a finer scale than deer in nonresidential areas. Smaller winter ranges and core areas of marked deer in a residential winter yard further imply greater concentration of resources available in these areas. Marked deer demonstrated flexibility in core winter range fidelity, a behavior that allows for more permanent shifts as habitat and food resources change or as new areas with appropriate resources are encountered. Our study suggests that low‐density residential areas in lowland conifer forests may provide an energetic advantage for deer during winter due to the assemblage of quality habitat interspersed with open areas and a variety of potential food sources in environments where movement is typically constrained by deep snow. Managers should consider the potential for changes in use of deer wintering areas prior to land conservation efforts and may need to adapt management strategies to reduce conflicts in communities occupied by deer during winter.

Regional application of the PnET‐BGC model to assess historical acidification of Adirondack lakes

The Adirondack region of New York has high inputs of acidic deposition and large numbers of acidic lakes. The biogeochemical model, PnET‐BGC, was applied to 44 statistically representative Environmental Monitoring and Assessment Program (EMAP) lake watersheds in the Adirondacks. Model simulations help provide an understanding of historical effects of acidic deposition on soils and lake waters. Model simulations indicate that median annual concentrations of SO42− and NO3− in the 44 EMAP lakes were 15.9 μeq/L and 3.8 μeq/L, respectively, in 1850, compared to the median current measured values of 88.8 μeq/L and 20.0 μeq/L. Simulated median values of pH, acid‐neutralizing capacity (ANC), and soil percent base saturation were 6.63, 67.7 μeq/L, and 12.3%, respectively, in 1850, compared to the median current measured values of 5.95, 27.8 μeq/L, and 7.9%. The estimated historical surface water acidification was greatest in lakes having low ANC below values of 100 μeq/L. This pattern of historical acidification is in agreement with a previous paleolimnological investigation.

The extracellular polymeric substances of desmids (Conjugatophyceae, Streptophyta): chemistry, structural analyses and implications in wetland biofilms

S.N. Kiemle, D.S. Domozych and M.R. Gretz. 2007. The extracellular polymeric substances of desmids (Conjugatophyceae, Streptophyta): chemistry, structural analyses and implications in wetland biofilms. Phycologia 46: 617–627. DOI: 10.2216/06–97.1Desmids represent a group of advanced green algae that are commonly found in biofilm communities of freshwater wetlands. Desmids secrete significant amounts of extracellular polymeric substances (EPS) that form an extensive mucilaginous sheath external to the cell wall and function in adhesion, gliding-based movements and ultimate ensheathment within the biofilm complex. We have initiated biochemical and structural analyses of the EPS of desmids isolated from biofilms from the southeastern Adirondack region of New York including Penium cylindris, Penium spirostriolatum, Cosmarium sp. 1, Cosmarium sp. 2, Pleurotaenium trabecula, Tetmemorus brebissonii, Netrium digitus, Netrium oblongum, Netrium interruptum and Netrium interruptum 2509. Cosmarium sp. 1 EPS appeared as a homogeneous sheath that encapsulated the cells, whereas P. trabecula EPS occurred as dispersed patches, and N. oblongum EPS was reticulated and striated. Polysaccharides were the major component of the EPS (52–76%), and lectin labeling revealed differences in polymer organization between saccoderm (labeled with Con-A, WGA and HPA) and placoderm (labeled with BS-I, PSA, UEA and HPA) desmids. Desmid EPS had significant uronic acid (3–29%) and protein (2–10%) content, and the polysaccharides were sulfated to varying degrees. Xylose and Fucose were the predominant monosaccharides with the major glycosyl linkages t-Xylp, 3,4-Fuc and t-Fuc. The unique EPS from N. oblongum was rich in galactose and uronic acid (29.3% w/w), extracellular polymers of P. spirostriolatum were composed predominantly of arabinose, and T. brebissonii EPS was enriched in glucose and galactose. EPS of P. trabecula and T. brebissonii was highly sulfated (10.2% and 14.7%, respectively). The EPS from New York and UTEX strains of N. interruptum were unique from each other. Overall, desmid EPS exhibits a conserved motif with the predominant component an anionic polysaccharide. The presence of deoxy-sugar subunits indicates the potential for hydrophobic interaction where anionic components may play important role in ionic cross-linking. The establishment of this baseline biochemistry provides the foundation for future dissection of core EPS molecules and associated functional groups and studies of EPS involvement in specific stages of biofilm development (e.g. adhesion).

Assessing pH changes since pre-industrial times in 51 low-alkalinity lakes in Nova Scotia, Canada

Diatom-based paleolimnological techniques were used to reconstruct lake acidification trends in 51 low-alkalinity Nova Scotia lakes that spanned gradients of dissolved organic carbon (DOC) concentrations and sulphate deposition. Pre-industrial, diatom-inferred pH values of these lakes were &lt;6.8, with 31 lakes having pre-industrial pH &lt; 6.0 and two lakes having pH &lt; 5.5. Lakes in Kejimkujik National Park documented the greatest pH decline (–0.4 pH unit (±0.2)) since the 19th century, whereas those in northern parts of the province (e.g., Cape Breton Highlands National Park) experienced little or no acidification, with a net mean pH decline = –0.1 pH unit (±0.2). While the sulphate deposition and diatom-inferred pH changes have not been as great as those observed in other acidified areas of northeastern North America (e.g., Adirondack region of New York or New England), Nova Scotia lakes have experienced biological changes toward more acidophilous diatom assemblages, especially in lakes with low pre-industrial pH values (currently with high DOC concentrations) located in Kejimkujik National Park, which receives the highest loading of sulphate deposition in Nova Scotia. However, the generally low pre-industrial pH values inferred for most of the study lakes suggest that many of these lakes were somewhat naturally acidic, but acidified further as a result of atmospheric deposition.

Exopolymer Production by the Green AlgaPenium margaritaceum: Implications for Biofilm Residency

Penium margaritaceum (Streptophyta) is a desmid that is commonly encountered in biofilms of wetlands of the Adirondack region of New York. This alga was isolated and has become an important model organism for laboratory studies dealing with the production and secretion of the extracellular polymeric substance (EPS) and biofilm behavior of desmids. Penium margaritaceum’s EPS macromolecules are used for three general biofilm‐based activities: the initial adhesion to a substrate, gliding motility along the substrate, and ensheathment within the biofilm matrix. EPS production is stimulated in experimental cultures by increasing the amounts of sodium nitrate or substituting sodium nitrate with ammonium salts. EPS levels decrease when cells are grown at 30°C or under high calcium levels. Ultrastructural and immunogold‐labeling studies show that the EPS is produced in a well‐defined and highly ordered endomembrane system. EPS is initially processed in the Golgi bodies and carried in osmiophilic vesicles to the peripheral cytoplasm, the site of active cytoplasmic streaming. The EPS vesicles fuse at specific loci of the plasma membrane and release their constituents to channels within the cell wall. The EPS is ultimately deposited on the cell surface. This secretory system allows the desmid to have a mobile supply of EPS ready for secretion at all times.

Using Patterns in Track‐Plate Footprints to Identify Individual Fishers

Abstract: If individuals can be identified from patterns in their footprints, noninvasive survey methods can be used to estimate abundance. Track plates capture fine detail in the footprints of fishers (Martes pennanti), recording rows of dots corresponding to tiny papillae on the animal's metacarpal pad. We show that the pattern of these dots can be used to identify individual fishers, similar to human fingerprints. A probabilistic model of uniqueness based on variation in spacing between 1,400 pairs of dots that we measured in prints of 14 different fisher feet suggests the probability of encountering a similar pattern in the print of a different foot by chance alone is ≤ 0.35n, where n = the number of dot pairs examined. This predicts a 0.00003 probability that a match made using 10 pairs of dots is false. Dot spacing from footprints made by the same foot was remarkably consistent (sN = 0.02 mm, n = 24 dot pairs). Combined, these results suggest dot patterns in fisher footprints were unique to individuals and were consistently reproduced on track plates. Empirical tests of matching accuracy were best with good‐quality prints, highlighting the need for experience judging when prints are usable. We applied print matching to fisher detections collected on track plates deployed at 500‐m intervals along 10 3.5‐km transects in the Adirondack region of New York, USA. Of 62 fisher detections, 85% had ≥ 1 footprint of suitable quality to compare with other high‐quality prints. We found that most detections from a transect were from the same individual fisher suggesting nonindependence of detections. Thus, data from traditional track‐plate deployments over small time periods cannot be used as a measure of abundance, but new study designs using print matching could obtain robust noninvasive, mark—recapture density estimates.

Desmids and Biofilms of Freshwater Wetlands: Development and Microarchitecture

Freshwater wetlands constitute important ecosystems, and their benthic, attached microbial communities, including biofilms, represent key habitats that contribute to primary productivity, nutrient cycling, and substrate stabilization. In many wetland biofilms, algae constitute significant parts of the microbial population, yet little is known about their activities in these communities. An analysis of wetland biofilms from the Adirondack region of New York (USA) was performed with special emphasis on desmids, a group of evolutionarily advanced green algae commonly found in these habitats. Desmids constituted as much as 23.7% of the total algal and cyanobacterial flora of the biofilms during the July and August study periods. These algae represented some of the first eukaryotes to colonize new substrates, and during July their numbers correlated with fluctuations in general biofilm parameters such as biofilm thickness and dry weight as well as total carbohydrate. Significant numbers of bacteria were associated with both the EPS sheaths and cell wall surfaces of the desmids. Colonization of new substrates and development of biofilms were rapid and were followed by various fluctuations in microbial community structure over the short- and long-term observations. In addition to desmids, diatoms, filamentous green algae and transient non-motile phases of flagellates represented the photosynthetic eukaryotes of these biofilms.

Changes in the chemistry of lakes in the Adirondack region of New York following declines in acidic deposition

Long-term changes in the chemistry of wet deposition and lake water were investigated in the Adirondack region of New York. Marked decreases in concentrations of SO 4 2 - and H + have occurred in wet deposition since the late 1970s. These decreases are consistent with long-term declines in emissions of SO 2 in the eastern US. Changes in wet NO 3 - deposition and NO x emissions have been minor over the same interval. Virtually all Adirondack lakes have exhibited large decreases in concentrations of SO 4 2 - , which coincide with decreases in atmospheric S deposition. Since 1992, concentrations of NO 3 - have also decreased in many (27 of 48) Adirondack lakes. As atmospheric N deposition has not changed appreciably over this period (1992–2004), the mechanism contributing to this apparent increase in lake/watershed N retention is not evident. Decreases in concentrations of SO 4 2 - + NO 3 - have resulted in increases in acid neutralizing capacity (ANC; 37 of 48 lakes) and pH (31 of 48 lakes), and decreases in concentrations of inorganic monomeric Al, particularly in acid-sensitive lakes. Concentrations of dissolved organic C (DOC) have also increased in some (15 of 48) lakes coinciding with decreases in acidic deposition. Examination of changes in lake chemistry by hydrologic classes showed that drainage lakes in watersheds with thin deposits of glacial till and mounded seepage lakes have generally been the most responsive to decreases in acidic deposition.

Trends in Summer Chemistry Linked to Productivity in Lakes Recovering from Acid Deposition in the Adirondack Region of New York

The US Environmental Protection Agency established the Adirondack Effects Assessment Program (AEAP) to evaluate and monitor the status of biological communities in lakes in the Adirondack region of New York that have been adversely affected by acid deposition. This program includes chemical analysis of 30 lakes, sampled two to three times each summer. Results of trends analysis for lake chemistry and chlorophyll a (chlor a) are presented for 1994 to 2003, and a general comparison is made with recent results of the Adirondack Long-Term Monitoring (ALTM) Program, which included chemical analysis of all but two of these lakes (plus an additional 24 lakes) monthly, year-round for 1992–2004. Increases in pH were found in 25 of the 30 AEAP lakes (P < 0.05) and increases in acid-neutralizing capacity (ANC) were found in 12 of the 30 lakes (P < 0.05). Concentrations of both SO42− and Mg2+ decreased in 11 lakes (P < 0.05), whereas concentrations of NO3− decreased in 20 lakes (P < 0.05). Concentrations of NH4+ decreased in 10 lakes at a significance level of P < 0.05 and in three other lakes based on P < 0.1. Concentrations of inorganic and organic monomeric aluminum generally were below the reporting limit of 1.5 μmol L−1, but decreases were detected in four and five lakes, respectively (P < 0.1). Concentrations of chlor a increased in seven lakes at a significance level of P < 0.05 and two lakes at a significance level of P < 0.1. A significant inverse correlation was also found between chlor a and NO3− concentrations in nine lakes at a significance level of P < 0.05 and two lakes at a significance level of P < 0.1. Results of AEAP analysis of lake chemistry were similar to those of the ALTM Program, although decreases in SO42− concentrations were more evident in the year-round ALTM record. Overall, the results suggest (a) a degree of chemical recovery from acidification during the summer, (b) an increase in phytoplankton productivity, and (c) a decreasing trend in NO3− concentrations resulting from the increased productivity.

Acid Rain Effects on Aluminum Mobilization Clarified by Inclusion of Strong Organic Acids

Assessments of acidic deposition effects on aquatic ecosystems have often been hindered by complications from naturally occurring organic acidity. Measurements of pH and ANCG, the most commonly used indicators of chemical effects, can be substantially influenced by the presence of organic acids. Relationships between pH and inorganic Al, which is toxic to many forms of aquatic biota, are also altered by organic acids. However, when inorganic Al concentrations are plotted against ANC (the sum of Ca2+, Mg2+, Na+, and K+, minus S042-, N03-, and Cl-), a distinct threshold for Al mobilization becomes apparent. If the concentration of strong organic anions is included as a negative component of ANC, the threshold occurs at an ANC value of approximately zero, the value expected from theoretical charge balance constraints. This adjusted ANC is termed the base-cation surplus. The threshold relationship between the base-cation surplus and Al was shown with data from approximately 200 streams in the Adirondack region of New York, during periods with low and high dissolved organic carbon concentrations, and for an additional stream from the Catskill region of New York. These results indicate that (1) strong organic anions can contribute to the mobilization of inorganic Al in combination with SO42- and N03-, and (2) the presence of inorganic Al in surface waters is an unambiguous indication of acidic deposition effects.