Geochemistry & Weathering – Dominant Control Factor Which environmental factor most strongly governs the rate and intensity of chemical weathering processes in rocks and soils?

Introduction / Context:
Chemical weathering transforms primary minerals into secondary products through reactions such as hydrolysis, oxidation, carbonation, and solution. Although vegetation and relief matter, the overarching control on reaction rates is the climatic regime, especially temperature and moisture availability.

Given Data / Assumptions:

• Chemical weathering requires water and is temperature-sensitive.
• We compare broad-scale controls: climate, vegetation, and topography.
• We seek the principal driver across landscapes and timescales.

Concept / Approach:
Climate dictates reaction kinetics (higher temperature speeds reactions) and water supply (precipitation controls dissolution, transport, and leaching). Humid tropical climates show intense chemical alteration and deep weathering profiles; arid/cold climates show slower rates. Vegetation influences acidity and organic acids locally; topography affects drainage and residence time but is secondary to the climatic envelope.

Step-by-Step Solution:

Verification / Alternative check:
Global weathering intensity maps correlate strongly with climatic zones (tropical > temperate > arid/polar), confirming climate’s primacy in chemical weathering rates.

Why Other Options Are Wrong:

• Vegetation: Important locally (root respiration, organic acids) but ultimately constrained by climate.
• Topography: Influences erosion and drainage; does not override moisture/temperature controls broadly.
• None of the above: Incorrect because climate is a well-established primary control.

Common Pitfalls:
Overemphasizing a lush forest’s effect without recognizing that such vegetation is itself climate-dependent; climate remains the first-order control.

Final Answer:
climate