Atmospheric Contributions to Water Quality of Streams in the Hubbard Brook Experimental Forest, New Hampshire

Abstract

The balances of input in atmospheric precipitation and discharge in streams have been determined for selected mineral constituents in three small tributaries to Hubbard Brook in the White Mountains of New Hampshire. Inputs and discharge of sulfate, am: monium, and nitrate were calculated from hydrologic data, together with chemical analyses of weekly samples of precipitation and streamwater taken over a 2-year period. The calculations show that precipitation provides most of the 30-50 kilograms of sulfate per hectare carried annually by the streams and that inputs exceed outflows of ammonium and of nitrate. Maximum effluent nitrate concentrations of 2 mg/1 (milligrams per liter) are observed in early spring. Measurements of pit indicate that the hydrogen ion is one of the major cations in precipitation over the area. Determinations were made of the discharge of bicarbonate, silica, and aluminum in the streams. Annual stream loads of silica ranged from 20 to 40 kilograms per hectare. Effluent bicarbonate and silica concentrations vary directly with each other and inversely with aluminum. (Key words' Forests; precipitation; quality of water) Hampshire. The objectives include' (1) the minerals; and with determinations of the indetermination of the rates of addition, internal put in precipitation and discharge in streams of calcium, magnesium, sodium, potassium, and circulation, and egress of dissolved mineral chloride [Likens et al., 19'6.7; Juang a•d Johnmatter in forested watersheds, and (2) the relation of these rates to the ecology of the son, 1967]. This report provides data on the balance forest and to the geochemistry of the watershed minerals. Individual phases of the inves-between the input in precipitation and the discharge in streams of sulfate, ammonium, * This report is contribution number 5 of the nitrate, hydrogen ion, bicarbonate, silica, and Hubbard Brook Ecosystem Study. Published as aluminum for three Hubbard Brook tributary a contribution to the U.S. Program of the International Hydrological Decade and the Inter-watersheds. Considerable information on these national Biological Program. balances in the watersheds studied has been 1115 1116 FI S I--IER ET acquired during the present study (June 19'64 has selected for intensive hydrologic study. through May 1966). I• is anticipated that a These small (12 to 43 hectare) watersheds are subsequent report covering a longer period will outlined in Figure I and designated W-2, W-4, establish more precisely the input-discharge and W-6. Measurements of precipitation and relationships for dissolved mineral matter in of streamflow in the watersheds are obtained intact sections of the forest. Concurrent chem-continuously by Forest Service personnel from ical measurements on the efiluent from a cut-a network of recording rain gages and stream over watershed within the study area are pro-gages. Monthly and annual water budgets are viding information on the effects of disturbances computed for each of the watersheds. Addiwithin the natural environment and, indire...

Effects of Forest Cutting and Herbicide Treatment on Nutrient Budgets in the Hubbard Brook Watershed‐Ecosystem

“…This would be expected from the relative constancy of cation and anion concentrations in stream water at Hubbard Brook Fisher, et al, 1968;Johnson, et al, 1969). In contrast, the conductivity of stream water from the deforested watershed is quite variable, ranging from 65 and 160 v.mhosjcm 2 at 25°C.…”

“…Sulfate concentration in stream water from the undisturbed watersheds is relatively constant in relation to the highly variable stream discharge Fisher, et al, 1968); and on close examination the sulfate concentration shows a very small and irregular volume concentration effect . In addition streamwater concentrations of sulfate seem to show some general, recurring seasonal patterns.…”

“…Nitrate concentrations in stream water from the undisturbed watersheds, show a pronounced, recurring seasonal pattern Fisher, et al, 1968). Average monthly concentrations are low ( <0.1 mg/1) throughout the summer growing season, increase in November, and reach values as high as 2 mg/liter during the spring (April) thaw (Fig.…”

“…PRECIPITATION CHEMISTRY Sulfate and hydrogen ions are the most abundant constituents (in terms of chemical equivalents) in precipitation falling on the watersheds ##Based on samples for 9 months. Samples collected from 1 September through 30 November were discarded because plastic screens were used on the collection apparatus (Juang and Johnson 1967;Fisher, et al 1968).…”

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“…As early as the late 1940s, he described the dying of trees from the top-down, hazy and suffocated atmospheres filled with ozones and acids, blackening rock surfaces, and other components widely observed and acknowledged today but virtually unknown to mainstream science in Reich's time. It was not until the late 1960s that similar reports began to emerge in public environmental discussions (Fisher et al 1968). …”