Environmental Geochemistry (GEOL0031) Part II

Flashcards covering key concepts on chemical weathering, ocean chemistry, and related geochemical processes.

What is the main source of dissolved elements in rivers?

The main source is the chemical weathering of rocks exposed at Earth’s surface.

What is congruent weathering?

It's when a mineral completely transforms into dissolved products with no solid residue remaining.

What is the chemical reaction for the dissolution of calcite?

CaCO3(s) + H2CO3(aq) −−↽−−⇀ Ca2+ (aq) + 2 HCO3 − (aq).

What are the three minerals mentioned that dissolve congruently?

Gypsum, halite, and quartz.

What type of weathering produces new minerals alongside dissolved solutes?

Incongruent weathering.

What happens during the oxidation of pyrite?

Pyrite reacts with dissolved oxygen to form oxidised iron hydroxides, releasing sulfate anions and acidity.

What mineral forms from the weathering of feldspar orthoclase under low intensity weathering?

Illite.

What mineral forms from the weathering of feldspar orthoclase under high intensity weathering?

Kaolinite.

How does chemical weathering influence global geochemical cycles?

It transports dissolved ions into the oceans and contributes to the closure of global geochemical cycles.

Why is chemical weathering important in relation to climate?

It can consume oxygen and carbon dioxide, thereby influencing long-term climate.