Dissolved inorganic carbon content

M.F1.C. Stoll, K. Bakker, G.H. Nobbe, R.R. Haese, Continuous-flow analysis of dissolved inorganic carbon content in seawater, Anal. Chem. 73 (2001) 4111. 

Redfield (1934), who analyzed the major elemental content of many samples of mixed plankton (phytoplankton and zooplankton) caught in nets towed through the surface ocean. They compared the carbon, nitrogen, and phosphorus composition of these collections to concentration profiles of dissolved inorganic carbon (DIC), NOs, and P04 throughout the water column. This pioneering research demonstrated that these three elements are continually redistributed in the ocean by selective removal into plankton cells and their remains (i.e., fecal pellets), which are then efficiently respired as they sink through the marine water column. 

Graneli, W., M. Lindell, and L. Tranvik. 1996. Photooxidative production of dissolved inorganic carbon in lakes of different humic content. Limnology and Oceanography 41 698-706. 

The major disadvantage of solid phase extraction is that it provides a chemically biased view of the DOM reservoir, and seems to preferentially extract compounds with relatively low amounts of N. Other problems include sample contamination by various resins and incomplete elution of adsorbed DOM. SoHd phase extraction remains, however, the only technique capable of reproducibly isolating DOM compounds within the entire range of MWs. Furthermore, the radiocarbon content (A " C) of DOC isolated by XAD resins is depleted relative to the total dissolved inorganic carbon (DIG) reservoir values for XAD isolates are between —300... 

To this purpose, isotopic data presented in this paper were obtained from several selected Gorleben groundwaters as part of the colloid characterisation programme. The contents of major and minor ions, light isotopes ( H, H, and and the U/Th isotopes were measured. Radiocarbon and were measured in dissolved inorganic carbon (DIG), ion the humic acid (HA-colloids) and fulvic acid (FA-solution) fractions of dissolved organic caibon (DOC). The and were also determined in dissolved sulphate phase. The U/Th isotope measurements were carried out on total and surface solid phases, colloid fraction (1-1000 nm particle size, HA) and solution (<1.5 nm, FA). 

In addition to its effects on microbial activity, solar UVR has direct effects on decomposition. A variety of recent studies have provided evidence that CDOM undergoes a complex array of other photoreactions that can involve a decrease in average molecular weight accompanied by cleavage to a variety of photoproducts [3-5,8,24,25,68,70,74,94-118], changes in isotopic content [60,119] and consumption of oxygen [59,68,106,116]. These reactions include the direct photochemical mineralization of the CDOM to carbon monoxide and dissolved inorganic carbon (DIC). Of these various direct pathways, the photoproduction of DIC is most efficient. 

The content is determined radiometrically from beta - activity or with mass-spectrometer. The following methods of presenting this activity are utilized 1) as specific value of beta-activity (per gram of carbon) 2) as the ratio of the absolute measured value and the standard one 3) as a deflection of absolute measured value from the standard one. In the first case is used directly specific activity in Becquerels per a gram of dissolved inorganic carbon. In the second case, the radiocarbon content is expressed in percent or parts per thousand from the standard activity according to equation... 

Mercury was detectable in the tissues of almost all freshwater fishes examined, with the majority of the mercury (>80-99%) present as methylmercury. Methylmercury is absorbed more efficiently than inorganic mercury from water, and probably from food, and is retained longer regardless of the uptake pathway. Three important factors modifying mercury uptake in aquatic organisms are the age of the organism, water pH, and the dissolved organic carbon content. In fish, for example, mercury tends to accumulate in muscle tissues of numerous species of freshwater and marine fishes and to... 

Hannaker and Buchanan [82] used a method based on wet oxidation with potassium persulfate [83] for the determination of dissolved organic content in concentrated brines following the removal of inorganic carbonates with phosphoric acid. The method involves wet oxidation with potassium persulfate at 130 °C followed by a hot copper oxidation and gravimetric measurement of the carbon dioxide produced. The technique overcomes difficulties of calibration curvature, catalytic clogging, and instrument fouling often encountered with instrumental methods. 

---