Sampling salt marshes

Aquatic Ecosystem and Fish. Metcalf et al. (2) studied the fate of diflubenzuron (radiolabeled separately in three different positions) in their model ecosystem. Diflubenzuron was dubbed "moderately persistent" in algae, snails, salt marsh caterpillars, and mosquito larvae as evidenced by limited biodegradability (Table IV). However, diflubenzuron and its nonpolar metabolites were not prone to ecological magnification in Gambusia fish. The lack of bioaccumulation of diflubenzuron residues in fish was substantiated by Booth and Ferrell (14) who used the channel catfish, Ictalurus, in a simulated lake ecosystem. They treated separate soil samples at 0.007 and 0.55 ppm, respectively. 

United Kingdom 20 salt marsh sediment samples, including 14 from Essex range of average values 2-50 (Essex 2-26, estimated background of 3) O Reilly Wiese, Bubb and Lester (1995)... 

North Bull Island salt marsh, Dublin Bay, Ireland top 20 cm of soil core samples Norway surface sediments in 210 lakes... 

Howes, B.L., Dacey, J.W.H., and Wakeham, S.G. (1985) Effects of sampling technique on measurements of porewater constituents in salt marsh sediments. Limnol. Oceanogr. 30, 221-227. 

Gallagher,. L. (1974). Sampling macro-organic matter profiles in salt marsh plant root zones. Soil Sci. Soc. Am. Proc. 38, 154—155. 

Reed, D.J. (1987) Temporal sampling and discharge asymmetry in salt marsh creeks. Estuarine, Coastal and Shelf Science 25. 

The advent of C-datlng technique provided an opportunity to more closely describe the rise in relative sea level since the last worldwide glaciation. Application of the technique to salt-marsh samples yielded quantitative evidence for the continuity and vertical extent of sea-level rise both worldwide (Shepard, 1963 Scholl and Stuiver, 1967 Milliman and Emory, 1968) and in southern New England (Barghoorn, 1953 Fair-bridge, 1961 Redfield, 1967). Radiocarbon dating of salt marshes revealed that the vertical development of the deposits has evidently kept pace with... 

Direct evidence for the formation of authigenic metal sulfide comes from x-ray microprobe and light-microscope examination of the salt-marsh sediments. In the presence of sulfur, iron monosulfides react to form pyrite, FeS2, which is known to occur as distinctive, characteristic aggregates of octahedral microcrystals of FeSj (framboids Berner, 1970 Sweeney and Kaplan, 1973). In the Farm River samples, framboidal FeSj was found to be common within at least the upper 14 cm of core examined, either as discrete framboids of 10- im diam. (Fig. 7) or as ordered clusters of framboids. Inspection of polished thin sections reveals a frequent association with the organic matrix, which appears to act as a template for their formation (see Fig. 8). 

Such independent estimates are available from direct measurements of Pb in total precipitation and from the standing crops present in undisturbed soils. Previous measurements of the atmospheric flux have been made in New Haven by Benninger (1976) using open-bucket collectors sampled at monthly intervals. Soil-standing crops have been measured at various sites in the eastern U.S., including a forested upland site within the Farm River salt marsh, and are compared in Table X. It is evident that the Pb flux derived from salt-marsh core FRl IB is indistinguishable from the current rate of deposition of Pb from the atmosphere in nearby New Haven. 

The salt-marsh flux is also in substantial agreement with estimates from soil-standing crops, but may be greater than the flux estimated from the Branford forested-soil sample by about 20%. Circumstances suggest that the standing crop measured in nearby soil may tend to underestimate the atmospheric Pb flux. The site is on a small island covered with deciduous forest surrounded by an extensive area of salt marsh and, therefore. 

An upland-soil source is also consistent with the metal concentrations found at lower levels in the salt-marsh cores. The iron content is generally proportional to the mass of inorganic sediment and is found in concentrations (almost 4%) considered reasonable for soil (Bowen, 1966). In an analogous plot for Cu, Fig. 16, the concentrations in deep peat and many of the lower clay-band samples are also typical of soil. 

Peat from the Farm River salt marsh, an estuarine marsh on the submerging coast of Connecticut near New Haven, was sampled by raising essentially undisturbed, meter-long cores, and was found to record trace-metal deposition from the atmosphere and sediment erosion from the land during the past century. 

Copper has been measured in soil using a portable electroanalytical device based on stripping voltammetry. In marine chemistry, sediments have been sampled and analysed in real-time by in situ solid-state voltammetric micro-electrodes. The analyser was used to examine levels of various redox species and trace metals, e.g. iron and manganese, in salt marsh sediments and other matrices. 

DeLaune et al. (1983b) triplicate determination in fresh and salt marshes duplicate in brackish marsh 13 sampling dates during 1980-1981. 

The amounts and profile distribution of various sulfur forms in Louisiana coastal marshes are important in understanding sulfur cycling as related to the origin and type of tidal wetland marshes. Sulfur forms and distribution were determined in P. hemitomon freshwater marsh, a S. patens brackish marsh, and a S. alterniflora salt marsh along a salinity gradient in Barataria Basin, Louisiana. Soil samples were fractionated into acid volatile sulfur (AVS), elemental sulfur, HCl-soluble sulfur, pyrite sulfur, ester sulfate sulfur, carbon-bonded sulfur, and total sulfur (see Chapter 11 for details). 

The brackish and fresh marshes contain similar sulfate contents, although means were higher in the brackish marsh. Average potential sulfate reduction rates over three sampling periods (Angnst, December, and April) were 45.9, 40, and 33.4 mol S m year respectively, for fresh, brackish, and salt marsh (Table 18.12). Turnover times are consistently longer in the salt marsh (approximately 40 days, Fignre 18.23) than in either the fresh or the brackish marshes (3-8 days). 

Mnnson, M.A., NedweU, D.B., Embley, T.M., 1997. Phylogenetic diversity of Archaea in sediment samples from a coastal salt marsh. Appl. Env. Microb. 63, 4729-4733. 

Reduced Sulfur Compounds in Marine Sediments. To determine the applicability of the bimane-HPLC technique to measure reduced sulfur compounds in sediment porewater samples, we compared the results of the methylene blue method of Cline (26). the DTNB procedure of Ellman (28) and the bimane-HPLC procedure outlined above. Cores included came from a Spartina foliosa marsh in Mission Bay (near San Diego, California), and an evaporation pond for the production of salt in south San Diego Bay (Table I). 

The rainwater of Bermuda is in near equilibrium with atmospheric Pc02 = 10-3.5 atm., and contains small amounts of sea salt (0.07 wt. % seawater). The rainfall of 147 cm y1 is seasonally distributed. The rain enters the saturated zone by two main paths direct rainfall on marshes and ponds, and percolation downward from the vadose zone as vadose seepage and flow through rocks during times of soil water excess (Vacher, 1978). Total annual recharge of the saturated zone is about 40 cm y-1 (Vacher and Ayers, 1980). The residence time of the groundwater has been calculated as 6.5 years, and the average age of the sampled water as 4 years (Vacher et al., 1989). Such estimates are necessary for calculations of carbonate mineral stabilization rates, as shown in a later section. 

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