Parameterizing Geochemical Models: Do Kinetics of Calcite Matter?

A chemical kinetics algorithm for geochemical modelling

A chemical kinetics algorithm is presented for geochemical applications. The algorithm is capable of handling both equilibriumand kinetically-controlled reactions in multiphase systems. The ordinary differential equations (ODEs) are solved using an implicit multistep backward differentiation formula (BDF) algorithm to ensure efficiency and stability when integrating stiff ODEs. An adaptive cont...

Dark Chocolate and Metabolic Syndrome; Do Polyphenols All that Matter?

Do Workers\' Remittances Matter for the Egyptian Economy?

Workers’ remittances constitute one of the most important sources of external finance for many developing countries. Although it shows a decreasing trend in recent years, Egypt after 1970s with her regular and massive labor migration to abroad has been still one of the gainer countries on remittances across the world. Empirical studies that implemented for various countries reveal workers’ ...

Calcite nucleation and precipitation kinetics as affected by dissolved organic matter at 25°C and pH > 7.5

We examined the processes of calcite nucleation and crystal growth to determine the dominant mechanism for precipitation of calcite in the presence of dissolved organic carbon (DOC). Our experiments, conducted at 25°C and at a Ca:HCO, molar ratio of 1:2, were performed with and without calcite seeds. Scanning electron micrograph observations showed that the particle size of calcite crystals in ...

Surface Complexation and Its Impact on Geochemical Kinetics*

The weathering of rocks, the formation of soils, the alteration and dissolution of sediments are a consequence of surface reac-. tions. Furthermore, many redox processes such as the oxidation of V02+, Mn2+ and Fe2+, the ncn-biotic degradation of organic substances and photosensitized processes are catalyzed by surfaces. The electric double layer theory, despite its efficiency in quantifying cer...