ALTERED WATER CHEMISTRY AND BROOK TROUT POPULATIONS IN TWO NORTHERN APPALACHIAN PLATEAU STREAMS BETWEEN 1988-90 AND 2005-07: EPISODIC ACIDIFICATION CONTINUED

Open Access
- Author:
- Jones, David Wayne
- Graduate Program:
- Environmental Pollution Control
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 17, 2010
- Committee Members:
- David Russell Dewalle, Thesis Advisor/Co-Advisor
William Edward Sharpe, Thesis Advisor/Co-Advisor - Keywords:
- water quality
trout
sulfate
sculpin
Stone run
recovery
monitoring
ERP
fish
episodic
emissions
deposition
chemistry
dam
Benner Run
brook
beaver
aquatic
Appalachian Plateau
aluminum
acidic episode
acidifcation
stream - Abstract:
- Two second order streams on the northern Appalachian Plateau of Pennsylvania were sampled during higher flows between August 2005 and March 2007 for numerous stream chemistry parameters, including pH, acid-neutralizing capacity (ANC), total dissolved sulfate (SO4), total dissolved aluminum (AlTD or Al) and dissolved organic carbon (DOC). Samples were collected during or immediately following precipitation events of rain or snow-melt events. Chemistry data for Stone Run, a documented low ANC acidic stream, and Benner Run, a higher ANC control stream, were evaluated with reference to discharge rate (m3/s/km2) and compared to historical episodic stream chemistry data collected between October 1988 and June 1990 to determine the extent of recovery from episodic acidification due to reductions in atmospheric deposition of sulfur oxides (SOx). My first hypothesis was that decreased air emissions and deposition of sulfur dioxide (SO2), which have been documented following implementation of the Clean Air Act Amendments (CAAA) of 1990, have caused a corresponding decrease in dissolved sulfate (SO4) in stream waters. As a consequence of decreased acid precipitation and SO4 deposition, my second hypothesis was that less AlTD would be leached from forest soils and found in streams, inferring reduced mortality of fish and other aquatic species sensitive to inorganic aluminum toxicity. My third hypothesis was that new equations would be required to predict total aluminum concentrations in these streams. Results indicate that the following stream chemistry changes occurred on Benner Run from the 1988-90 study period to the 2005-07 study period: the median sulfate concentration increased 21% (from 4.7 to 5.7 mg/L); the median aluminum concentration increased 223% (from 42 to 94 ug/L). The following changes occurred on Stone Run between the same study periods: the median sulfate concentration decreased 14% (from 9.6 to 8.3 mg/L); the median aluminum concentration decreased 9% (from 200 to 173 ug/L). Comparing medians using Mann-Whitney tests, three of these four differences were found to be statistically significant, with only the aluminum decrease in Stone Run not statistically significant. The percentage of samples with > 0.2 mg/L dissolved aluminum increased from 1.2% to 10.0% on Benner Run and decreased from 50.2% to 48.3% on Stone Run. Based on these findings, slight recovery of Stone Run and biologically significant degradation of Benner Run has occurred on these watersheds between the two study periods. Other stream chemical parameters were compared: conductivity, chloride (Cl), nitrate (NO3-N), calcium (Ca), magnesium (Mg), potassium (K), sodium (Na), and dissolved inorganic carbon (DIC); and regression equations were developed for all parameters to predict aluminum concentrations. Although the correlations between dissolved sulfate and aluminum concentrations are believed to explain some of the observed stream chemistry changes as hypothesized, these were not the highest correlations on either stream. The two streams were found to have distinctly different concentration ranges of sulfate and DOC correlated with higher flows and with higher AlTD (> 0.1 and > 0.2 mg/L). New regression equations were developed to predict AlTD from flow (m3/s), discharge (m3/s/km2) and the chemical parameters measured to obtain: R2, adjusted R2, PRESS and predicted R2. These equations show DOC (R2 = 0.749) was the strongest single predictor of AlTD on Benner Run. ANC (R2 = 0.458) was the best single predictor of AlTD on Stone Run, slightly better than pH (R2 = 0.403) then SO4 (R2 = 0.298), consistent with episodic acidification theory. DOC did not contribute significantly to predictions of AlTD (R2 = 0.000) on Stone Run. Effects of varying beaver activity and a series of beaver dams and ponds complicate the explanation of some of the altered water chemistry on Benner Run, including AlTD highly correlated with DOC, which would be expected to have low toxicity if chelated by organic matter. But brook trout population estimates by the Pennsylvanian Fish and Boat Commission (PFBC) above the beaver dams declined 72.6% from 1982 to 2004, with a maximum biomass of 72.40 kg/ha in 1984 and a minimum biomass of 19.81 kg/ha in 2004. This data, along with increased SO4 and AlTD concentrations below the dams, supports a conclusion of continued episodic acidification and biologically significant change on this watershed despite decreasing SO4 emission and deposition trends. It is likely that at least several more decades will be required to confirm significant recovery on both Benner Run and Stone Run.
Tools
-
Download MS_EPC_Thesis_Jones_Appendix_E_Benner_Regressions_2010-11-22a.pdfDownload MS_EPC_Thesis_Jones_Appendix_D_Stone_N_60_2010-11-23.pdfDownload MS_EPC_Thesis_Jones_2010-12-07a.pdfDownload MS_EPC_Thesis_Jones_Appendix_A_Field_Chemistry_N_137_2010-11-23.pdfDownload MS_EPC_Thesis_Jones_Appendix_C_Benner_N_50_2010-11-23.pdfDownload MS_EPC_Thesis_Jones_Appendix_F_Stone_Regressions_2010-11-22a.pdf
- Request paper in alternate format.