Sediment surface

Fig. 14-6 Profiles of potential temperature and phosphate at 21 29 N, 122 15 W in the Pacific Ocean and a schematic representation of the oceanic processes controlling the P distribution. The dominant processes shown are (1) upwelling of nutrient-rich waters, (2) biological productivity and the sinking of biogenic particles, (3) regeneration of P by the decomposition of organic matter within the water column and surface sediments, (4) decomposition of particles below the main thermocline, (5) slow exchange between surface and deep waters, and (6) incorporation of P into the bottom sediments.

Madsen EL, CL Mann, SE Bilotta (1996a) Oxygen limitations and aging as explanations for the field persistence of naphthalene in coal tar-contaminated surface sediments Environ Toxicol Chem 15 1876-1882. 

FIGURE 3.5 a) Relationship between HgT and MeHg in surface sediments across 49 ecosystems (from Benoit et al. 2003) and b) relationship between HgT and MeHg in surface sediments from 122 streams across the United States. (Source From Krabbenhoft et al. 1999.)... 

It is useful to check for the existence of gravel or stones in the sediment beforehand since these may obstruct the insertion of a sampling borer. Putting a pipe with a length of approximately 30 cm and diameter 20-30 cm into sediment makes it easy to collect surface sediment. It is best to collect sediment with a trowel or a spatula after water inside the pipe has been removed. 

Take surface sediment with a spatula, then insert a sampling borer to take cores. 

Figure 4 Method of taking sediment samples in a paddy field minimizing contamination with surface sediment and water...

Hamilton El, Clifton RJ. 1980. Concentration and distribution of the transuranium radionuclides 239+240pu 238pu anc[241 Am in Mytilus edulis, Fucus vesiculosus and surface sediment of Esk estuary. Mar Ecol Prog Ser 3 267-277. 

McCartney M, Kershaw PJ, Woodhead DS, et al. 1994. Artificial radionuclides in the surface sediments of the Irish Sea, 1968-1988. Sci Total Environ 141 103-138. 

Guimaraes, J.R.D., Meili, M., Hylander, L.D., Castro e Silva, E., Roulet, M., Mauro, J.B.N., and Lemos, R.M.A., Mercury net methylation in five tropical flood plain regions of Brazil High in the root zone of floating macrophyte mats but low in surface sediments and flooded soils, Science of the Total Environment, 261 (1-3), 99-107, 2000. 

Chen L, Yu C, Shen C, Zhang C, Liu L, Shen K, Tang X, Chen Y (2010) Study on adverse impact of e-waste disassembly on surface sediment in East China by chemical analysis and bioassays. J Soils Sediments 10(3) 359-367. doi 10.1007/sll368-009-0176-8... 

Kayal, S.I., Connell, D.W. (1990) Partitioning of unsubstituted polycyclic aromatic hydrocarbons between surface sediments and the water column in the Brisbane River estuary. Aust. J. Mar. Freshwater Res. 41, 443-456. 

Kang YH, Sheng GY, Fu JM, Mai BX, Zhang G, Lin Z, Min YS (2000) Polychlorinated biphenyls in surface sediments from the Pearl River delta and Macau. Mar Pollut Bull 40... 

Galanopoulou S, Vgenopoulos A, Conispoliatis N (2005) DDTs and other chlorinated organic pesticides and polychlorinated biphenyls pollution in the surface sediments of Keratsini harbour, Saronikos gulf, Greece. Mar Pollut Bull 50(5) 520-525... 

In coastal environment, detrital and authigenic Fe and Mn oxides, which accumulate in oxic surface sediments, play a pivotal role in determining the geochemical behaviour of arsenic (Mucci et al., 2000) and selenium (Belzile et al., 2000). Arsenic and selenium differ in their affinities for metal oxide surfaces. Although both adsorb onto iron oxides, arsenate (As(V)) adsorbs more strongly than arsenite (As(lll)), and selenite (Se(IV)) adsorbs more strongly than selenate (Se(VI)) (Belzile et al., 2000). 

Van Cappellen, P. Wang Y. 1996. Cycling of iron and manganese in surface sediments a general theory for the coupled transport and reaction of carbon, oxygen, nitrogen, sulfur, iron and manganese. American Journal Sciences, 296, 197-243. 

Nevertheless, surfactant sorption isotherms on natural surfaces (sediments and biota) are generally non-linear, even at very low concentrations. Their behaviour may be explained by a Freundlich isotherm, which is adequate for anionic [3,8,14,20,30], cationic [7] and non-ionic surfactants [2,4,15,17] sorbed onto solids with heterogeneous surfaces. Recently, the virial-electrostatic isotherm has been proposed to explain anionic surfactant sorption this is of special interest since it can be interpreted on a mechanistic basis [20]. The virial equation is similar to a linear isotherm with an exponential factor, i.e. with a correction for the deviation caused by the heterogeneity of the surface or the energy of sorption. 

In the rivers, high concentrations of NP in sediment were observed [25] over relatively long stretches of about 10 km downstream from a sewage effluent discharge point (compared to elevated concentrations over a stretch of only 1 km length in a similar study conducted in the Detroit river [27]). Owing to the tidal current the horizontal mixing of surface sediments is possibly more extensive than in nontidal areas [25]. 

In the Strait of Georgia study, surface sediment concentrations in the vicinity of the effluent averaged 1.5 pgg-1, with maximum concentrations of approximately 3 pg g-1. At 20 km distance from the outfall, the concentration had dropped to 0.30 pg g-1 [28]. 

While much of the chlordecone that was present in contaminated sediments in 1976 is still in the sediment, it is continuously being buried under several centimeters of new sediment each year (Huggett and Bender 1980). Storm activities and dredging are of concern because they would result in reenrichment of the surface sediments in areas with chlordecone contaminated sediment previously buried by natural ongoing sedimentation processes in the estuary (Huggett and Bender 1980 Lunsford etal. 1987). 

Pearson, A., A.P. McNichol, G.C. Benitez-Nelson, J.M. Hayes, and T.I. Eglinton. 2001. Origins of lipid biomarkers in Santa Monica Basin surface sediment A case study using compound-specific 14C analysis. Geochimica et Cosmochimica Acta 65 3123-3137. 

Whelan, J.K. 1977. Amino acids in surface sediment core of the Atlantic abyssal plain. Geochimica et Cosmochimica Acta 41 803-810. 

In contrast, limestones from the Equatorial Pacific show much heavier Zn. The surface sediment of the carbonate-dominated core TT013 19MC in the Equatorial Pacific (1° 52 S, 139° 43 W, z = 4500 m) has a 5 Zn value of 0.79%o, while Pichat et al. (2003) analyzed the carbonate fraction of the core OOP 849 (0° 11.59 N, 110° 31.18 W, z = 3851 m) over the last 175 ka and found a downcore variation from 0.6 0.2 to 1.2 0.2%o (Fig. 6). The reproducibility of the measurements is consistent with the internal errors. Small scale fluctuations along the core are dominated by two significant 35.2 and 21.2 ka periods. The former is difficult to assign to a known astronomical feature but the latter corresponds to a forcing by the precession of the Earth s axis of rotation. 

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