Slab Cabin Run

Explanation for the inverse relationship between pH and Pqo, in carbonate-dominated systems such as Slab Cabin Run is most obvious if we recast Eq. (5.20) in log form... 

The data in Table 5.4 show that the total alkalinity (chiefly HCOj) is practically constant at 2.80 0.04 (SD) mM, regardless of pH. The product of ATco, i is nearly constant at 10 between 8.4 and 16.5°C. Thus, ApH A(-log Pco,) in the stream. In essence, the stream has a constant background composition, perturbed diumally by the effect of photosynthesis on its dissolved CO2 content and thus its pH. This behavior of Slab Cabin Run has been generalized in Fig. 5.3, which is based on Eq. (5.28) and on MINTEQA2 calculations. 

Some chemical analyses of waters from Slab Cabin Run, near State College, PA, May 28-29, 1971, and the corresponding apparent CO2... 

Figure S3 Example trends of the apparent CO2 pressure in bars in a New Jersey coastal plain groundwater aquifer (Langmuir 1969), in the Floridan carbonate aquifer (Back and Hanshaw 1970), and in Slab Cabin Run, a small stream. Arrows denote the direction of groundwater flow. The data for Slab Cabin Run represent the diurnal cycle in May (Jacobson et al. 1971). See Table 5.4.

Sec. 6.10 A Surface-Water Carbonate System Slab Cabin Run... 

A SURFACE-WATER CARBONATE SYSTEM SLAB CABIN RUN... 

TABLE 6.5 Chemical, carbon isotopic, and solar radiation analyses for Slab Cabin Run, Nittany Valley, State College, PA... 

TABLE 6.6 Computed carbonate speciation, COj pressure, total carbonate Cj, and calcite saturation index, S4, of samples 1-8 from Slab Cabin Run... 

Figure 6JO Variations in log Pco,. pH, (per mil units, PDB), and the saturation indices of calcite (5/ ) and dolomite (5/ ) in Slab Cabin Run, near State College, Pennsylvania. Based on Jacobson et al. (1971).

A downward component of flow is present during periods of high seasonal water table and when Spring Creek and Slab Cabin Run are in flood. During periods of flood, surface water comes into contact with isolated carbonate bedrock outcrops located along the valley slopes of these creeks and provide local pathways for contaminated surface waters to enter the karst aquifer. Elsewhere, flood waters come in contact with residual and transported soil that blankets the lower portion of valley slopes, hence, preventing the direct entry of surface water into the local aquifer. 

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