Estuaries measurements

Zeeuwen et al. (1983) observed the atmospheric dispersion and combustion of large spills of propane (1000-4000 kg) in open and level terrain on the Musselbanks, located on the south bank of the Westerscheldt estuary in The Netherlands. Thermal radiation effects were not measured because the main objective of this experimental program was to investigate blast effects from vapor cloud explosions. 

The transfer of P from the continents to the ocean is separated into two distinct pathways. The flux of reactive P (F25) is estimated via measurements of dissolved organic and inorganic P in rivers. A small correction (33% after Kaul and Froelich, 1984) is added to the measured values to account for P released from particles within the estuaries. This P is transported directly to the surface ocean and is... 

Measuring the isotopic composition of U in estuaries has the potential for further constraining the interpretations of uranium behavior. However, this has been hampered by large uncertainties in conventional methods using counting techniques. While rivers often display ( " U/ U) activity ratios above equilibrium, the ratios generally do not... 

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). 

Somayajulu BEK (1994) Uranium isotopes in the Hooghly Estuary, India. Marine Chem 47 291-296 Spechler RM (1994) Saltwater intrasion and the quality of water in the Floridian Aquifer system, northeastern Florida. US Geol Surv Water Resource Invest Rept 92-4174 Sun Y, Torgersen T (1998) Rapid and precise measurement for adsorbed " Ra on sediments. Marine Chem 61 163-171... 

Spencer and Brewer [144] have reviewed methods for the determination of nitrite in seawater. Workers at WRc, UK [ 145] have described an automated procedure for the determination of oxidised nitrogen and nitrite in estuarine waters. The procedure determines nitrite by reaction with N-1 naphthyl-ethylene diamine hydrochloride under acidic conditions to form an azo dye which is measured spectrophotometrically. The reliability and precision of the procedure were tested and found to be satisfactory for routine analyses, provided that standards are prepared using water of an appropriate salinity. Samples taken at the mouth of an estuary require standards prepared in synthetic seawater, while samples taken at the tidal limit of the estuary require standards prepared using deionised water. At sampling points between these two extremes there will be an error of up to 10% unless the salinity of the standards is adjusted accordingly. In a modification of the method, nitrate is reduced to nitrite in a micro cadmium/copper reduction column and total nitrite estimated. The nitrate content is then obtained by difference. 

The reaction manifold describing the automated determination of ammonia is shown in Fig. 6.1. Two alternative modes of sampling are shown discrete and continuous. Discrete 5 ml samples contained in ashed (450 °C) glass vials are sampled from an autosampler (Hook and Tucker model A40-11 1.5 min sam-ple/wash). For high-resolution work in the estuary, the continuous sampling mode is preferred. The indophenol blue complex was measured at 630 nm with a colorimeter and the absorbance recorded on a chart recorder. 

Wu et al. [388] carried out measurements of the enrichment of Atrazine on the micro surface water of an estuary. These authors used a micro surface water sampling technique with a 16 mesh stainless steel screen collecting bulk sampled from the top 100-150 pm of the surface. Atrazine concentration in the actual micro surface was estimated to vary in the range 150-8850 pg/1. 

In general, silver concentrations in surface waters of the United States decreased between 1970-74 and 1975-79, although concentrations increased in the north Atlantic, Southeast, and lower Mississippi basins (USPHS 1990). About 30 to 70% of the silver in surface waters may be ascribed to suspended particles (Smith and Carson 1977), depending on water hardness or salinity. For example, sediments added to solutions containing 2 pg Ag/L had 74.9 mg Ag/kg DW sediment after 24 h in freshwater, 14.2 mg/kg DW at 1.5% salinity and 6.9 mg/kg DW at 2.3% salinity (Sanders and Abbe 1987). Riverine transport of silver to the ocean is considerable suspended materials in the Susquehanna River, Pennsylvania — that contained as much as 25 mg silver/kg — resulted in an estimated transport of 4.5 metric tons of silver to the ocean each year (USEPA 1980). The most recent measurements of silver in rivers, lakes, and estuaries using clean techniques show levels of about 0.01 pg/L for pristine, nonpolluted areas and 0.01 to 0.1 pg/L in urban and industrialized areas (Ratte 1999). 

Jeffery, W. H. and Paul, J. H. (1986). Activity measurements of planktonic microbial and microfouling communities in a eutrophic estuary, Appl. Environ. Microbiol., 51, 157-162. 

Although the sediments in these systems accumulate Se over time, the small isotopic contrast suggests that dissimilatory reduction is not the dominant accumulation mechanism. If dissimilatory reduction of Se(VI) and/or Se(IV) to Se(0) by bacteria were the dominant mechanism, one would expect the accumulated Se(0) to be enriched in the lighter isotope. In the San Francisco Estuary case, this assumes that the isotopic fractionations measured by Ellis et al. (2003) can be extrapolated to much lower concentrations. Incorporation of Se into algae and macrophyte tissues, followed by decay of some material and conversion of its Se to Se(0), is more consistent with the observed Se isotope data. Notably, the mean Se isotope composition of the Se(0) in the sediments of the Herbel et al. (2002) study was identical to that of the macrophytes. 

Similar to fish, PFOS is the dominant PFC found in aquatic invertebrates such as shrimp, mussels, clams and oysters [132,133]. A few papers report on PFC levels in bivalves. Concentration ranging from 1 to 6.0 ng/g wwt) in oysters were reported from the Ariake Sea [134] and China [133], respectively. Cunha et al. [135] measured high concentrations of PFOS in mussels from several estuaries in the North of Portugal. PFOS was detected in all the samples analysed, and the concentrations were ranging 36.8 to 126.0 ng/g wwt. In a more recent work, Nania et al. [130] found higher PFOA than PFOS in clam but comparable levels were found in mussels, which were attributed to differences in habitat and feeding behaviour. 

---