Bicarbonate river water

River water chemistry is determined by the relative concentrations of major dissolved components (bicarbonate, calcium ion, silica, and sulfate), which are in turn controlled by the environment. Rivers in precipitation-dominated... 

Titrations were performed on untreated, filtered, and UV-treated filtered river water samples at in situ and adjusted pH values. The effect of pH on copper speciation was investigated by titration of filtered Newport River water at pH 7.0 and filtered Newport and Neuse waters at pH 8.0. Newport River water was adjusted to pH 7.0 by decreasing the partial pressure of CO2 from the initial ambient value of about 10 times the atmospheric level. To adjust the pH to 8.0, sodium bicarbonate was added to bring the river water samples to a concentration of 0.5 mM with subsequent adjustment of Pc02 Titrations were also conducted at pH 7,0 in model solutions consisting of 0.01 KNO3 and 0.1 mM NaHC03 with and without the addition of 0.75 histidine to test electrode behavior in solutions of known chemistry. 

Bicarbonate is the main anion in river water because of the reaction of C02-rich soil water with both calcium carbonate and silicate rocks (see Chapter 2). Thus, neutralization of acid in reactions with more basic rocks during weathering creates cations that are balanced by anions of carbonic acid. In this sense the composition of rocks and the atmosphere determine the overall alkalinity of the ocean. 

The water soluble inorganic calcium compounds, most commonly bicarbonate, Ca(HC03)2, leaches permanently to river waters and finally migrates to the ocean. This bicarbonate forms in the reactions of calcium carbonate with carbonic acid. 

Chemical Composition of Stream Water. Streams in the Mattole River basin contain relatively low concentrations of dissolved salts, as might be expected because of the high rainfall. Representative analyses of the river water are presented in Table II. Calcium, magnesium, and sodium are the major cations, and bicarbonate and sulfate are the major anions. Mean discharge for a 20-year period (1912-13, 1951-68) was 1331 ft3 sec 1 (37.69 m3 sec 1) and mean annual discharge was 1.189 X 109m3 (37). 

The interactions with calcium var) the organic size depending on the organic concentration. Metal complexation showed an increase in size in UF fractionation (Aster et al. (1996)). The ions present in river water were measured simultaneously with UF fractionation to ascertain how they interact with HSs of various sizes (Kiichler et al (1994)). In concentrated solutions aggregate formation is favoured, while for low concentrations intramolecular contractions result in smaller sizes (Engebretson and von Wandruszka (1994)). Huber (unpublished) reported a decrease in measured size with calcium bicarbonate addition. 

The three analyses given below with their ion balances represent the titer changes for raw river water containing some NHJ. After bicarbonate removal, natural concentration occurs in a cooling system which can undergo partial biological nitrification. 

Let us first look at the terrestrial waters, lakes, and rivers. The total amount of the terrestrial waters on the Earth is about 5 x lO kg. With a few exceptions like Great Salt Lake and Dead Sea (in Jordan/Israel), the terrestrial waters contain relatively low levels of dissolved ionic species (low salinity). Though it varies widely, the salinity of river waters has been estimated on average as about 100 ppm (that is, 100 g of ionic compounds of various kinds per 1 million grams (1 m volume) of water). On average, the contents of various elements (compounds) in rivers are HCOj" (bicarbonate anion) >Si(OH) (silicate) >Ca +>SO/ >CL>Na > Mg +. These ions come dissolved from the rocks and soils through which the river water runs. 

Rainwater and snowmelt water are primary factors determining the very nature of the terrestrial carbon cycle, with photosynthesis acting as the primary exchange mechanism from the atmosphere. Bicarbonate is the most prevalent ion in natural surface waters (rivers and lakes), which are extremely important in the carbon cycle, accoxmting for 90% of the carbon flux between the land surface and oceans (Holmen, Chapter 11). In addition, bicarbonate is a major component of soil water and a contributor to its natural acid-base balance. The carbonate equilibrium controls the pH of most natural waters, and high concentrations of bicarbonate provide a pH buffer in many systems. Other acid-base reactions (discussed in Chapter 16), particularly in the atmosphere, also influence pH (in both natural and polluted systems) but are generally less important than the carbonate system on a global basis. 

The carbonic acid thus formed is rich in oxygen-16. The mildly acid ground-water as well as the water of rivers and lakes, which is, therefore, also enriched in oxygen-16, dissolves limestone from surrounding rocks, to form calcium bicarbonate, which is soluble in water ... 

What has happened to the bicarbonate and calcium delivered to the ocean by river runoff As described later, these two ions are removed from seawater by calcareous plankton because a significant fraction of their hard parts are buried in the sediment. In contrast, the only sedimentary way out of the ocean for chloride is as burial in pore waters or precipitation of evaporites. The story with sodium is more complicated— removal also occurs via hydrothermal uptake and cation exchange. Because the major ions are removed from seawater by different pathways, they experience different degrees of retention in seawater and uptake into the sediments. Another level of fractionation occurs when the oceanic crust and its overlying sediments move through the rock cycle as some of the subducted material is remelted in the mantle and some is uplifted onto the continents. 

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