High marsh

The salt marsh can be divided into two distinct environments high and low marsh (3). The high marsh is only subject to tidal flushing during the highest tides. This study focused on the low marsh where tidal flushing is regular. 

Choice of site for detailed study was based on the following criteria (1) the surface and subsurface vegetation should be typical high-marsh species, e.g., S. patens, (2) the surface relief should be minimal (3) the core should penetrate into peat formed before human influence became significant and (4) the probability of physical disturbance in the past should be low. 

It is a common experience among those who stand in place on the high marsh that the surface slowly depresses and forms a water-filled pool around one s feet. Based on this observation and the generally water-saturated condition of the peat, we anticipated that water would soon fill... 

Fig. 11. The depth distribution of total activity of Pb in contiguous slices of peat from the Farm River salt marsh shows that the semilog plot is convex in the region about 34 cm. Below 34 cm to the top of the distinct D. spicata rhizome layer at 50 cm, the activity is low and approximately constant, averaging 0.83 dpm gm , which is taken as supported background. Below this layer, the supported Pb activity is irregularly lower. The dominant species of vegetation varies with depth as indicated, but all species found are characteristic of high marsh.

The burrowing crab, Uca pugnax, is evidently present in considerable numbers on the marsh and probably represents the single greatest threat to the sedimentary record. This crab reportedly occurs in mean densities of 205/m in the S. alterniflora marshes of Georgia, but in Rhode Island only 2.7 3.8/m were counted in early fall (Teal, 1962 Nixon and Oviatt, 1973). In this study area their burrows were obvious under the relatively open stands of S. alterniflora, but the dense stands of S. patens grass often prevented observation of the high-marsh surface. 

In summary, deposition from the atmosphere almost always impinges directly upon the high-marsh surface. Moreover, the standing crop of excess Pb now found beneath the salt-marsh surface or nearby soil is in essential agreement with that expected from measured atmospheric fluxes. Therefore, the salt-marsh standing crop of excess Pb seems best explained as quantitative retention of atmospheric deposition. 

Mudge s concept of salt-marsh accretion clearly incorporates the notion that the grasses of the high marsh maintain their position during a gradual change in relative sea level, by upward growth. However, the special... 

The vertical development of the high-marsh surface is governed by vegetative growth, not particle deposition. The extensive, interwoven. 

Salt marsh sediments and water were collected from the high-marsh zone of a marsh on Sapelo Island, Georgia. Water/sediment slurries (50 1 [vol/vol]) were prepared by homogenizing water and sediment for 30 s in a... 

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