LONGITUDINAL TRENDS IN PH AND ALUMINUM CHEMISTRY OF THE COXING KILL, ULSTER COUNTY, NEW-YORK

The purpose of this work was to characterize the Al chemistry along th e longitudinal pH gradient of the Coxing Kill and thereby provide a ba sis for an in depth study of aluminum chemistry and transport as a fun ction of PH. Water samples were collected along the pH gradient and an alyzed for monomeric Al species, strong acid anions, base cations, amm onium, dissolved organic C and dissolved silica. Inorganic monomeric A l, organic momonmeric Al and dissolved organic C decreased in concentr ation as the stream's drainage area and pH increased. The ratio of org anic to inorganic monomeric Al and the concentration of all other spec ies increased with increasing pH. An abrupt change in stream chemistry occurred in conjunction with the gradual changes expected for a low o rder stream draining an acid sensitive watershed impacted by acid depo sition. This abrupt change partially resulted from geological characte ristics of the watershed.