Mud flats

At least one of the organolead compounds has been shown to be a normal constituent of the aqueous environment. Tetramethyl lead has been found as a product of anaerobic bacterial metabolism in lake sediments [23]. It should perhaps be sought in the air over coastal mud flats. 

FIGURE 12 1 Major topographic features of the Los Angeles basin with inland valleys and mountains. Station locations A, Highland B, City Creek C, Mud Flat D, Rim Forest. Aircraft flight paths for the study area are also shown. Reprinted with permission from Edinger et al. 

Stuart, V., Head, E.3.H. and Mann, K.H., in press. Relative contributions of benthic diatoms and Spartina alterniflora (Loisel) detritus to the nutrition of the amphipod Corophium volutator (Pallas) on a Bay of Fundy mud flat. 3. Exp. Mar. Biol. Ecol. 

Coastal wetlands have long been noted for their relatively high emission of volatile sulfur gases to the atmosphere indeed the typical odor of marshes often is due largely to DMS. Several studies have reported emissions of DMS, H2S, and other sulfur compounds, dimethyldisulfide, carbonyl sulfide, and carbon disulfide (10-12.40-42). DMS and H2S constitute the bulk of the flux, with DMS predominating in vegetated areas and H2S in mud flats. Fluxes of DMS... 

Ruminant animals produce dimethylsulfide, a fraction of which is exhaled.4 Therefore, cows breath is a source of this compound in terrestrial atmospheres. Dimethylsulfide is produced in enormous quantities by marine organisms. This volatile compound is the largest source of biogenic sulfur in the atmosphere and is responsible for some of the odor emanating from coastal mud flats. 

Reaves (1986) described another study specifically aimed at relating calcium carbonate preservation to chemical diagenesis in sediments. He compared Mercinaria shells and pore water chemistry in intertidal mud flat and tidal creek... 

The microphytobenthos consist of an assemblage of benthic diatoms (principally pen-nate in shape) that typically migrate vertically in the sediments over a diurnal period (Serodio et ah, 1998). Enhanced turbidity in shallow regions from resuspension events can limit light penetration thus, the most effective time for primary production occurs in intertidal sand and mud flats during daytime exposure periods (Guarini et ah, 2000,... 

During the aquatic phase plants are detached from the sediments and drift with the current. They contribute to the carbon pool of the main channel of the Amazon River and also accelerate the colonization of newly created open areas formed by the deposition of sediments. Quick colonization creates a range of different stages of allogenic succession in the floodplains. The velocity of the successional process will depend upon the stability of the habitat. Isolated floodplain lakes, where deposition rates of sediments are small, show a slow but gradual colonization process while, processes on sand bars and mud flats in the river channel are more dynamic and often reversible (Junk and Piedade 1997). 

Halimione portcuiacoides upper mud flat lower mud flat... 

The shore is part of a larger zone referred to as the coast, the entire area that is affected by the sea. The coast includes the familiar sand and surf, as well as mud flats, tide pools, and marshes. The coast begins at the point where waves start breaking as they roll in toward the shore, and it extends to the farthest reaches of waves and tides on land. In some localities, the distance between the first breaking waves and the highest tides is just a matter of meters in others, it encompasses miles. 

Mud flats are subject to the coming and going of tides, but unlike beaches and tide pools, they are protected from waves. Water cannot drain through muddy soil like it does on beaches where soil particles are loosely packed. Mud particles are small and tightly packed, so they hold water in place. When water occupies the spaces between mud particles, there is no room for oxygen. As a result, mud flats are anaerobic environments that support only organisms that can survive in low or no oxygen. 

In some places, coastlines are rocky, varying in structure from cliffs to piles of boulders. In other areas, they are sandy beaches or wide mud flats. The residents of these ocean edges are exposed to extremely stressful living conditions that vary in salinity, levels of dissolved gases, and temperature. 

There has been much work reported in recent years on the sedimentology and stratigraphy of the tidally influenced marshes and high tidal mud-flats (Allen, 1985a, b, 1986,1987a, b, c, d, 1988,1990a, b, c, d, e, f, 1992a, b Allen Rae, 1986, 1987, 1988). 

The formation of mud-flats, which develop into saltmarshes, is occurring in response to an apparently climate-driven, estuary-wide cycle of erosion... 

The purpose of this paper is to outline the physical environmental factors involved in the functioning of the intertidal system and briefly review the impact on the biogeochemical processing of nitrogen, phosphorus and silicon. Consideration of saltmarshes is excluded. Discussion is focused on the often extensive areas of non-vegetated sand and mud flats that are uncovered by the tides on a daily basis and for which there is a limited amount of published information. 

Presenting research from a wide range of scientists working on intertidal sediments - both mud flats and saltmarshes - this book is of importance to all environmental scientists. 

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