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Weathering of minerals in soils provides important plant nutrients and consumes acidity, yet mineral weathering is difficult to observe and quantify. We derived present-day weathering flux estimates for soil minerals in a forested watershed in central New Hampshire using a geochemical mass balance. The Cone Pond watershed is characterized by low-alkalinity surface waters and acidic Spodosols developed on a thin mantle of locally derived till, making it susceptible to continued inputs of acid precipitation. Weathering reactions were developed on the basis of observed patterns of mineral abundance in the soil profile and measured mineral chemistry. The dissolution of approximately 171 mol [ha.sup.-1] [yr.sup.-1] of plagioclase feldspar is the predominant weathering reaction at Cone Pond. Weathering fluxes of hornblende, biotite, chlorite, and potassium feldspar ranged from 3 to 20 tool [ha.sup.-1] [yr.sup.-1], an order of magnitude lower. When normalized to their abundances in the soil, however, hornblende and chlorite had the fastest weathering rates, as measured by cation release. Chemical weathering, mainly of plagioclase, resulted in the neutralization of only 52% of incoming acidity. Furthermore, silicate weathering could only account for the release of about 53 tool [ha.sup.-1] [yr.sup.-1] of Ca, compared to the observed net output (stream loss minus bulk precipitation input) of 75 mol [ha.sup.-1] [yr.sup.-1]. On the basis of these observations and a companion study, we conclude that current acid inputs exceed the ability of Cone Pond soils to neutralize hydrogen ion, and that depletion of approximately 22-53 mol [ha.sup.-1] [yr.sup.-1] of Ca from labile soil pools is occurring in this area. The rate of Ca depletion is one-third to one-eighth of the rate estimated for a more base-rich watershed nearby.

Research on acidic forest soils typically uses unbuffered salt solutions as extractants for exchangeable cations. Our lab uses 1 M NH[SUB4]C1 extractant for exchangeable cations (Ca, K, Mg, and Na) and 1 M KCl for exchangeable aluminum. The resulting high dissolved salt solutions presented chronic analytical problems on flame atomic absorption spectrophotometer (AAS) and direct current plasma spectrometer (DCP). More recently, the analyses completed on a simultaneous, axial inductively coupled plasmaatomic emission spectrometer (ICP-AES) have continued to be problematic. Although ICP manufacturers provide application notes that list some precautions to help minimize the salt effect, such issues are seldom mentioned in published articles and can be misleading when interpreting results. This paper describes various modifications that have been tried to eliminate the effects of high dissolved salts when using ICP. Adjustable parameters such as gas flow rates, sample introduction rates, dilution rates, and accessories were tested. Results of each modification were evaluated by comparing method detection limits, recovery rates, and carry-over values to determine the most effective operating ICP system. For example, a 15 second increase of sample uptake and rinse times for the KC1 method decreased the method detection limit (MDL) by 12%, recovery rate by 12%, and carry-over by 25%. [ABSTRACT FROM AUTHOR]

Discusses the need for incorporating water quantity and quality goals in forest management decisions, related to silvicultural practices, at a local level. Reasons behind the need; Features of a decision support software, designed to provide structured project-level analysis of management alternatives based on water goals; Types of water quantity and water quality goals.

BSTRACT: Experimental cuttings on two small, hardwood-forested watersheds in New England showed that annual streamflow can be increased as much as 41 percent. Most of the increase occurred in summer and early autumn when additional streamflow is most needed. Revegetation caused the annual increases to nearly disappear within 4 years after complete forest clearing. [ABSTRACT FROM AUTHOR]

Depletion of Ca in forests and its effects on forest health are poorly quantified. Depletion has been difficult to document due to limitations in determining rates at which Ca becomes available for ecosystem processes through weathering, and difficulty in determining changes in ecosystem storage. We coupled a detailed analysis of Sr isotopic composition with a mass balance at Cone Pond Watershed, New Hampshire, in order to further constrain estimates of these processes. Strontium acted as an analog for Ca in most processes except translocation of nutrients within forest vegetation. Variability in mineralogic and Sr isotopic composition of bedrock and soils complicated assessment of the 87Sr/86Sr ratio released to solution by weathering reactions. By conducting a mass balance on atmospherically derived Ca, it is possible to distinguish Ca weathering losses from Ca leached from ecosystem pools. The calcium weathering rate estimated by this method was less than half of that determined by mass balance assuming steady state conditions. [ABSTRACT FROM AUTHOR]

Changes in storm flow as a result of forest clearing by cutting of trees and subsequent applications of herbicides were determined for a small mountainous watershed in New Hampshire by using a paired watershed as a control. Reduction of transpiration and interception losses produced wetter soils with less opportunity for storing rainfall. Consequently, quick flow volumes and instantaneous peaks were nearly always increased during the growing season. The absence of the hardwood forest canopy also caused earlier and more rapid snowmelt and affected most spring storm flow events involving snow water. In contrast, storm events occurring after soil moisture recharge in the fall and before the start of spring snowmelt were unaffected by forest clearing. Although the spring and summer storm flow changes were readily detectable, their magnitude was not great. The maximum increase in individual quick flow was 30 mm for the summer streamflow season and just over 50 mm during spring snowmelt. Mean quick flow changes were much lower. The relatively small amount of forest clearing currently taking place in New England headwaters should not increase downstream flood potential. [ABSTRACT FROM AUTHOR]