As water interacts with surface rocks it dissolved inorganic carbon

concentrations increase from the following types of reactions:

Carbonate Rocks:

CO2+ CaCO3+ H2O ↔Ca2++ 2HCO3-(notice that 1 mole HCO3-

comes from the rock and 1 from the atmosphere ).

Silicate Rocks:

The “Urey reaction”CO2+CaSiO3+H2O↔Ca2++HCO3-+SiO2(aq)↔CaCO3+SiO2

[reaction intermediates](notice that 1 mole HCO3-comes from the atmosphere: all HCO3-is "non-rock").

CaSiO3can be thought of as representing “silicate rock” (i.e., similar

reactions can be written for all the primary rock forming silicate minerals)

For diagrams you can further refeer the papers given below:

http://web.pdx.edu/~sytsmam/limno/Limno09.6.IonsandANC.pdf

Dear Dr. Asoori Latha,

Kalff Chapters 13 and 14 – provided exhaustive information on sources of ions in water; special emphasis given on the chemical reactions – very good and educative.

Earlier, I have read this. Actually, I am searching some simple scatter plots – based on the measured water parameters (major cations/anions), by which the source rock can be identified.

You have also incorporated some basic information on carbonate & silicate rocks. It is appreciable. Thanks.

Dear Dr. Batabyal:

To get an idea of the source rock or parent material from altered components be it solid , liquid or gaseous is old and the methods proposed are often overstretched by the users. Weathering pertains to the sort of alteration processes most strongly impacted by a wide range of parameters from different spheres (atmosphere, hydrosphere, biosphere, lithosphere, pedosphere). All of them have a more or less strong influence on the fluid component and are strongly dependent on the latitude and longitude on the globe expressed by the climate zonation. You may get nice diagrams but at the very end it will remain an equation with too many unknowns. You can only reduce the number by using a wide range of disciplines applied and different media. There is no philosopher´s stone, unfortunately or fortunately (?).

From time to time one has also to take a look at the basis of sciences.

Harald G. Dill

If I understand your question correctly, your goal is to identify host rocks based on dissolved elements in groundwater. I am quick to admit this is not my a rea of expertise, but it sounds like a challenging concept. The abundance of trace elements certainly relates to the composition of host rock from which they are derived, but there are a number of other factors that influence the concentration of dissolved elements. This is particularly true for elements like Fe, which is relatively insoluble under oxidizing conditions (e.g, water that is in atmospheric equilibrium). Or Si, where solubility is much  greater  under basic pH, relative to neutral or acidic pH. The importance of these effects is illustrated here in western Washington, USA where lowland areas are largely covered by a thick blanket of Pleistocene and early Holocene alluvium, with some peat bog deposits. The trace element chemistry of  groundwater near the buried peat deposits is markedly different from the surrounding area, because the decomposing organic matter produces strongly reducing conditions, combined with the chelating ability of organic compounds. These factors produce highly elevated levels of heavy metals, particularly Fe and Mn.  At first look, the elevated levels of these elements would seem to suggest a metal-rich bedrock source, but  in actual fact these levels result from local  environmental conditions, not rock composition.

Best wishes,

George Mustoe

Dr. George E. Mustoe - Yes,  you have understood my question.

The last sentence of your answer is very important - the role of local environmental conditions in the chemistry of groundwater. The paper you have attached is useful to understand the bacterial activities in the concentration of Mn and Fe. Thanks