Dissolved coastal waters

Th is produced by U, which is present in low concentrations in river waters therefore most of the Th found in estuaries is supplied either in situ or from ocean water. The first " Th measurements in coastal waters revealed increased removal from dissolved to particulate phase with increasing proximity to shore (Bhat et al. 1969). 

Baskaran and Santschi (1993) examined " Th from six shallow Texas estuaries. They found dissolved residence times ranged from 0.08 to 4.9 days and the total residence time ranged from 0.9 and 7.8 days. They found the Th dissolved and total water column residence times were much shorter in the summer. This was attributed to the more energetic particle resuspension rates during the summer sampling. They also observed an inverse relation between distribution coefficients and particle concentrations, implying that kinetic factors control Th distribution. Baskaran et al. (1993) and Baskaran and Santschi (2002) showed that the residence time of colloidal and particulate " Th residence time in the coastal waters are considerably lower (1.4 days) than those in the surface waters in the shelf and open ocean (9.1 days) of the Western Arctic Ocean (Baskaran et al. 2003). Based on the mass concentrations of colloidal and particulate matter, it was concluded that only a small portion of the colloidal " Th actively participates in Arctic Th cycling (Baskaran et al. 2003). 

A method described by Florence and Farrer [584] separated tin from its associated lead by distillation from an aqueous sulfuric acid medium into which the vapour from boiling 50% hydrobromic acid is passed. The distillate provides an ideal supporting electrolyte for the determination of tin (II) (produced by reduction with hydrazinium hydroxide) by anodic stripping at a rotating vitreous-carbon electrode in the presence of codeposited mercury [585,586]. The tin is deposited at -0.70 V versus the SCE for 5 minutes, and then stripped at -0.50 V during a sweep from -0.70 V to -0.45 V at 5 V per minute. Tin in seawater is coprecipitated on ferric hydroxide, and the precipitate is then dissolved in the aqueous sulfuric acid, and subjected to the above procedure. The average content for Pacific coastal waters was found to be 0.58 xg/l. 

Ogura and Hanya [62-65] investigated the components of the ultraviolet absorption in an attempt to devise a useful method for oceanic dissolved organic carbon measurements. They concluded that while the method might have limited application in coastal waters, most of the absorption in oceanic waters was due to the inorganic components, principally nitrate and bromide ions. 

Alkylphenol derivatives in the North Sea and UK coastal waters Blackburn and Waldock [11] undertook a survey of water concentrations of alkylphenols (APs) in rivers and estuaries in England and Wales. Locations were selected to represent a wide range of possible AP inputs, from both agricultural and industrial sources. For all samples, both filtered and unfiltered water were treated, to determine both the dissolved and the total extractable APs by GC-MS. 

In coastal waters containing very high dissolved organic carbon... 

The impact of anthropogenic nutrient emissions in the coastal zone is heightened by its chemical speciation. Pollutant nitrogen and phosphorus are delivered to the coastal waters primarily in inorganic form, whereas most of the natural riverine dissolved nitrogen and phosphorus are components of organic compounds, i.e., DON and DOE Thus, the pollutant nutrients are delivered to the coastal waters in a chemical form that can be directly assimilated by coastal plankton, whereas the organically bound (natural) forms must first be remineralized. 

Determination of Dissolved Silicate in Estuarine and Coastal Waters by Gas Segmented Continuous Flow... 

This is reflected in the complexation capacity. Usually a high organic matter content of river and estuarine waters will, together with the colloids in the "dissolved" fraction, result in a high CCqu (100 - 500 nM Cu2+), Fig. 7a. Coastal waters (Fig. 7b), as a result of mixing with seawater, have a lower CCcu (60 - 150 nM Cu2+). Open ocean surface waters of the North Atlantic have a CC u of 20 - 70 nM Cu2+, which in case of low in situ biological activity might be well below this value (Fig. 7c). 

The rivers play a major role in the transfert of carbon and mineral nutrients from land to the sea and influence significantly the biogeochemical processes operating in coastal waters. Quantification of the material transport, both in the dissolved and particulate forms, has been attempted by several authors in the past (Clarke, 1924 Holeman, 1968 Garrels McKenzie, 1971 Martin et al., 1980 Meybeck, 1982 Milliman Meade, 1983). Depending on the type of sampling techniques and methods of calculations employed there are differences in the reported fluxes. A major problem in such calculations is the paucity of reliable data from some of the major rivers of the world especially of Asia (see e.g. Milliman Meade, 1983). Additionally the difficulty of obtaining representative samples from the rivers will adversely affect flux calculations. Most of the inferences drawn on the nature and transport of riverine materials rest on data collected randomly - at different points in time and space. Seasonal variations in the transport of materials are very common in some of the major world rivers, and in some cases more than 60 % of the material transport occurs within a very short period of time. Furthermore, available data are not always comparable since the analytical techniques used differ from river to river. 

Newell, R.C. and Lucas, M.I., 1981. The quantitative significance of dissolved and particulate organic matter released during fragmentation of kelp in coastal waters. Kieler Meeresforsch., 5 356-369. 

Middelboe, M., B. Nielsen, and M. Sondergaard. 1992. Bacterial utilization of dissolved organic carbon (DOC) in coastal waters — determination of growth yield. Archiv fur Hydrohiologie Beiheft Ergebnisse der Limnologie 37 51-61. 

Zanardi-Lamardo, E., Clark, C. D., Moore, C. A., and Zika, R. G. (2002). Comparison of the molecular mass and optical properties of colored dissolved organic material in two rivers and coastal waters by flow field-flow fractionation. Environ. Sci. Technol. 36(13), 2806-2814. 

Riso, R.D., B. Pemet-Coudrier, M. Waeles, and P. Le Corre. 2007. Dissolved iron analysis in estuarine and coastal waters by using a modified adsorptive stripping chronopotentiometric (SCP) method. Anal. Chim. Acta 598 235-241. 

Despite the critical role dissolved gases have in many of the biogeochemical cycles of estuaries and coastal waters, only recently have there been large-scale collaborative efforts (e.g., BIOGEST) addressing the importance of coupling between estuaries and the atmosphere. 

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