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Aquatic chemical kinetics reaction rates of processes in natural waters
[...]... Carbonates in the System CaC0 3 -MgC0 3 Roland Wollast 16 Kinetics of Colloid Chemical Processes in Aquatic Systems 431 447 Charles R O'Melia 17 Kinetics of Chemical Weathering: A Comparison of Laboratory and Field Weathering Rates Jerald L Schnoor 18 Transport and Kinetics in Surficial Processes 475 505 Abraham Lerman Index 535 AQUATIC CHEMICAL KINETICS 1 KINETICS OF CHEMICAL TRANSFORMATIONS IN THE ENVIRONMENT... ,l"lIl\'/llalY reaction; (2) collections of elementary reactions that represent entire 2 Kinetics of chemical transformations in the environment chemical processes; (3) dynamic models that represent complete natural and engineered systems; (4) unique characteristics of surface chemical reactions; and (5) kinds of kinetic information and how they can be used to answer questions such as the ones listed above Chemical. .. or caused by human intervention (such as the dispersion of a pesticide), Since change is such a major concern, it should not be Nlilprising that chemical kinetics is an integral component of models natural Nystellls, Intrinsically "kinetic" questions concerning the nature and behavior of IIlIt IIlal systems include: 0" W hen will the maximum concent1'ation of a pollutant appear in a system, and how... dynamics of the system On the most fundamental level, chemical kinetics is a molecular description of chemical reactions A series of encounters between chemical species is hypothesized, and the level of agreement between the proposed mechanism and experimental findings is critically examined In special circumstances, the molecular description of chemical reactions allows generalizations to be made concerning... yields a proportional increase in encounter ""'IIIl"I1CY, This observation, called the principle of mass action (Gardiner, 1969) I~ till' hasis for quantitative treatment of reaction kinetics, Reaction 7, which II'Pll'Sl'I1ts the overall reaction stoichiomctry, is also balanced for mass and 4 Kinetics of chemical transformations in the environment charge Reaction 7 is a composite of several molecular... concentrations of other reaction species We will leave the discussion of processes involving two or more elementary reactions for a later section Most elementary reactions involve either one or two reactants Elementary reactions involving three species are infrequent, because the likelihood of simultaneous three-body encounter is small In closed, well-mixed chemical systems, the integration of rate equations... III" chemical kinetics of interest can be defined by a single elementary 11'01111011, hut the reaction occurs in an open system, the differential equation for It'ill IlIlIl must be elaborated accordingly In a later section, we will discuss how I " II chemical reaction and mass transport can be accounted for in calculating I h,III}'l'S in species concentrations as a function of time \I 1 I, Tht'ory of. .. in time When I;." and Tphys are of the same magnitude, rates of sorption, desorption, I'Il'l'ipitation, and dissolution must be accounted for, along with rates of flow ill KINETICS AT INTERFACES ( '''('mical reactions at interfaces are of great importance in many areas of aquatic I ""llIislry Adsorption and partitioning phenomena are responsible for distrib1I111l~ chemicals among available phases In. .. rate-controlling step, l'Xl'rling the strongest influence on the rate of final product formation t\ generality can be made about all reactions in series The rate of final product I, "Illation is influenced by the rate constants of all prior reactions steps Overall I" Il'S of product formation are most influenced by the step with the longest , Ii" lacteristic time This step constrains the rates of subsequent... limiting, the competitive reaction with the highest rate constant also generates the greatest amount of reaction product ,'\ 1 Reversible Reactions Many chemical reactions important in the water environment are reversible When the reaction of interest is far from equilibrium, the concentration of the pn lduct is small, and the rate of the back reaction is low relative to the rate of the forward reaction . AQUATIC CHEMICAL KINETICS AQUATIC CHEMICAL KINETICS Reaction Rates of Processes in Natural Waters Edited by WERNER STUMM Swiss Federal Institute. 16. Kinetics of Colloid Chemical Processes in Aquatic Systems 447 Charles R. O'Melia 17. Kinetics of Chemical Weathering: A Comparison of