Assessment of Acidic Deposition Effects on the Chemistry and Benthos of Streams of the East-Central Adirondack Region

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Project Summary. The Western Adirondack Stream Survey (WASS), conducted in 2003-2005, showed that acidic deposition was causing toxic forms of Al to move from soils to streams in 66% of the 565 watersheds assessed in the study region. The WASS encompassed only 20% of the Adirondack region, and for the remaining 80% (referred to hereafter as the East-Central Adirondack region), there is l...

 

Project Summary.  

 The Western Adirondack Stream Survey (WASS), conducted in 2003-2005, showed that acidic deposition was causing toxic forms of Al to move from soils to streams in 66% of the 565 watersheds assessed in the study region.  The WASS encompassed only 20% of the Adirondack region, and for the remaining 80% (referred to hereafter as the East-Central Adirondack region), there is little information on the extent of soil and stream acidification.  Based on lake-chemistry data, acidification in the East-Central Adirondack region has been considered minimal relative to the Western Adirondack region.  However, some lake acidification has been identified, and WASS results showed that lake acidification under represents stream and soil acidification (Lawrence et al., 2008a).  The 19,969 km2 that comprise the East-Central Adirondack region cannot be assumed to be impervious to acidic deposition effects because wide variations occur in atmospheric deposition levels (Weathers et al., 2006), geology, topography, surface hydrology, and soils.  These variations translate into varying levels of sensitivity that need to be quantified to support policies for restoring and protecting these natural resources.  The proposed study covers over two thirds of the wilderness areas of the Adirondack Park and the 47,000 ha above 900 m elevation.

WASS was implemented as a pilot study to assess chronic and episodic stream chemistry and biota in the region of New York considered most impacted by acidic deposition.  A new sampling approach was developed for WASS, making it the first regional assessment of stream chemistry during both base flow and high flow conducted in the U.S.  We therefore propose to apply the sampling and analysis methods developed in the recent WASS pilot study to conduct the East-Central Adirondack Stream Survey (ECASS).  This study will involve: (1) collection of water samples in approximately 200 streams during summer base flow, spring snowmelt, and fall high flow, (2) collection of water samples in streams that had been previously sampled multiple times in the 1980s, (3) collection of periphytic diatoms in all streams, (4) collection of macroinvertebrates in 40 streams, and (5) collection of stream water, diatoms and macroinvertebrates at selected high elevation sites.  Streams will be randomly selected for sampling from the population of accessible streams.  To enable extrapolation of results to all streams in the Adirondack Park, GIS coverages (including mapping of atmospheric deposition to small watersheds) will be used to verify that acid sensitivity and deposition levels do not differ between the populations of accessible and inaccessible streams.  Acidification of stream water will be fully assessed with conventional methods and also with the base cation surplus (BCS), an index developed in the WASS that better distinguishes acidic deposition from natural acidity than ANC and pH measurements.  Results will be combined with WASS data to develop an assessment of the entire Adirondack region, including (1) acidic deposition effects on fundamental components of stream ecosystems and (2) the current soil conditions with respect to acidic deposition effects. 

The need for the proposed assessment is emphasized by the uncertain energy future in the U.S. and by the change in climate that has been underway in the Adirondack region for over 3 decades (Dello, 2007).  Ecosystem effects from the changing climate are likely to have already begun and will undoubtedly be tied to the legacy of acidic deposition effects.  The proposed work will provide landscape-scale information on current conditions that is currently unavailable for this extensive area valued for its natural ecosystems.  Furthermore, results will provide data needed to determine if critical loads are being exceeded and to assess recovery potential through forecast modeling—efforts currently underway to evaluate the success of air pollution control policies.

Summary of Project Methods.  The Western Adirondack Stream Survey (WASS) was conducted in 2003-2005 to assess the effects of acidic deposition on stream chemistry, diatoms, macroinvertebrates, and soil chemistry in the western Adirondack region. The project was implemented as a pilot study in which a new, cost efficient sampling method was developed to enable regional characterization of both chronic and episodic acidification.  The new approach involved flow-synchronized sampling of 200 streams over a 3-day period.  A new chemical index of acidification, termed the base cation surplus, was also developed in the WASS.  The BCS enabled the effects of acidic deposition to be distinguished from natural acidity by relating base cation availability to the mobilization of inorganic Al.

The WASS approach was successful in determining the percentage of streams and total stream length prone to episodic and chronic acidification for the 565-stream study population.  The WASS also showed that the base cation surplus (BCS) related directly to impacts on diatom and macroinvertebrate communities, which were moderately to severely impacted by acidic deposition in 66 and 52 % of streams, respectively.   Furthermore, quantitative relationships were developed between stream chemistry and soil chemistry that enabled a regional assessment of soil acidification from the extensive stream data collected.  The sampling design and methods of the WASS enabled acidic deposition effects to be assessed in terms of the linkages between terrestrial and aquatic ecosystems rather than the conventional approach of assessing aquatic and terrestrial effects separately.  Acceptance and success of these methods has been demonstrated by publication in high-impact, peer-reviewed journals.  Publications thus far cover the following topics: (1) the development and application of the base cation surplus (Lawrence et al., 2007), (2) stream chemistry results (Lawrence et al., 2008b),  and (3) macroinvertebrate results (Baldigo et al., 2009).   Articles on diatom results and comparisons between stream chemistry in 2003-2005 and the early 1980s, are in preparation.  Application of the approaches used in the diatom assessment have been published previously (Passy et al., 2006; Passy et al., 2004).

For the proposed project we plan to apply the sampling and analysis methods developed in the WASS to the remainder of the Adirondack Park.  This study will be implemented through: (1) sampling of approximately 200 streams randomly chosen from the population of  accessible streams in the East-Central Adirondack region during summer base flow, fall high flow, and spring snowmelt, (2) collection of periphytic diatoms at all stream sites (3) collection of macroinvertebrates at 40 stream sites, (4) additional sampling of sites that had been previously sampled multiple times in the 1980s to assess changes over time, and (5) estimation of soil-base saturation (Oa and upper B horizon) in all sampled watersheds using the soil-stream relationship developed in the WASS.  Acidification of soils and stream water will be assessed with the base cation surplus, as well as ANC and pH measurements.  We also plan to add two new components; (6) sampling of approximately 12 selected high-elevation streams in the High Peaks region and (7) a GIS assessment to determine if there are any differences between the populations of accessible and inaccessible streams with regard to features that could affect acidic deposition impacts.  These features include atmospheric deposition levels, geology (bedrock and surficial deposits) elevation, slope, precipitation, and the topographic index, which defines a relative value for soil drainage.  This analysis will enable results of the survey to be extended to the entire population of Adirondack streams.

Results of this proposed work will be combined with WASS results to provide an assessment of acidic deposition effects on fundamental ecosystem components—stream chemistry, diatoms, macroinvertebrates, and also soils, throughout the Adirondack region.  Details of methods are published in the WASS final report (Lawrence et al., 2008a).

Project Location by County

Adirondack Region:
Clinton County, NY, Essex County, NY, Franklin County, NY, Fulton County, NY,
Hamilton County, NY, Herkimer County, NY , Lewis County, NY, Oneida County, NY,
Saint Lawrence County, NY, Saratoga County, NY, Warren County, NY, Washington
County, NY