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Trends in Catskill Stream Water Quality: Evidence From Historical Data
Author(s) -
Stoddard John L.
Publication year - 1991
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/91wr02009
Subject(s) - streams , water quality , environmental science , nitrate , hydrology (agriculture) , deposition (geology) , acid neutralizing capacity , acid deposition , nitrogen , environmental chemistry , chemistry , geology , soil science , ecology , soil water , geomorphology , geotechnical engineering , biology , computer network , organic chemistry , sediment , computer science
Historical data for large streams in the Catskill Mountains indicate that acidic deposition has significantly influenced water quality, but that this effect is most observable in early (pre‐1945) data, and consists primarily of increased base cation (CaMg) concentrations. More recent data suggest that landscape disturbance currently exerts a stronger influence on acid/base status of large streams than does acidic deposition, resulting in increases in both CaMg and acid‐neutralizing capacity (ANC). Estimates of SO 4 2− concentration indicate that SO 4 2− is a conservative ion in the Catskills, and stream water concentrations have decreased since reaching maximum values around 1970, consistent with temporal trends in emissions and deposition in the northeastern United States. Nitrate concentrations, on the other hand, have increased substantially in all but one stream in the past two decades, independent of any change in nitrogen deposition in the region; changes in the capacity of watersheds to retain nitrogen are hypothesized as causes of increased stream water NO 3 − . In small, undisturbed streams, increases in NO 3 − and decreases in CaMg appear to offset the effects of reduced SO 4 2− , and lead to decreasing trends in ANC.