Acid pulses from snowmelt at acidic cone pond, New Hampshire

Abstract

A study was undertaken to examine whether ‘acid pulses’ from snowmelt created permanent changes in a pond's chemistry. Water samples were collected from clearwater acidic Cone Pond in the White Mountain National Forest, New Hampshire. The pond, inlet, and outlet were intensively sampled throughout winter and early spring 1983–84. Thaws brought more H+ into upper waters of the pond, but most was gone within a week. In contrast, SO42− and Al showed dilution with increased streamflow into the pond, and NO3− was only detected in ice, slush, and surface waters. Bottom waters were anoxic throughout the winter and had pH 6.0 compared to 4.7 for most of the water column. Alkalinity at the bottom rose from 0 in November 1983 to 190 μeq L−1 in April 1984. Between November and April the pond gained Al but lost SO42− and H+. Most of the Al gain came after ice-out when loading through the inlet increased, but during the final snowmelt a temporary increase in Al concentration was also seen throughout the water column.