The cedar swamp has acidic soil. Therefore, the streams in this site should have lower concentrations of calcium & magnesium than in our site, located on basalt bedrock.  Comparing the actual concentrations does not show this to be true.  This may be due to the fact that cedar is evergreen while the trees in our site are deciduous. Comparisons of the calcium and magnesium concentrations in precipitation show a much higher concentration under the cedar canopy than under the winter deciduous canopy. This may be due to the presence of these elements on the foliage of the cedar. We suggest that the concentrations of calcium and magnesium in the streams are comparable between the two sites only because these elements are washing off the cedar foliage.

The enrichment ratio provides a much better measure for comparison.  This ratio has been calculated by dividing the stream concentration by the funnel concentration for a given site.  This value shows the concentration of the elements by the stream from the precipitation - local geology plays a more significant role in this value than in the total values.  When comparing sites, the enrichment ratios tell a much different tale than the actual values.  In this case, one can clearly see that the geology of Totoket Mountain greatly increases concentrations of calcium and magnesium, while the soils of the cedar swamp do not contribute nearly so much of these elements.

Addtiionally, Hubbard Brook shows the median enrichment ratio.  This can be expected due to the granitic gneiss bedrock of the site. This rock tend to contribute lower amounts of Ca & Mg than the basalt found on Totoket Mountain, while still contributing significantly more than the acidic soils of a swamp.

Finally, Puerto Rico may have higher absolute concentrations than all the other sites due to the tropical climate.  (Lack of data prevents the calculation of enrichment ratios.)  Perhaps the soil there is weathering at a higher rate, contributing more Ca & Mg to the streams.

We suggest that sodium concentrations in the rainfall and stream are correlated with proximity to the ocean.   The enrichment ratios and absolute values are similar for both the sites near the ocean (the swamp and Totoket Mountain sites), while the inland site (Hubbard Brook) contributes far more sodium to the stream water than the precipitation. Additionally, the concentration of sodium in Hubbard Brook precipitation and streamwater is significantly lower than the corresponding concentrations in the coastal areas.

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