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Consider the following activities : 1. Spreading finely ground basalt rock on farmlands extensively 2. Increasing the alkalinity of oceans by adding lime 3. Capturing carbon dioxide released by various industries and pumping it into abandoned subterranean mines in the form of carbonated waters How many of the above activities are often considered and discussed for carbon capture and sequestration?
Explanation
The correct answer is Option 3 (All three) because each activity represents a scientifically recognized method for carbon capture and sequestration (CCS) or carbon dioxide removal (CDR).
- Activity 1 (Enhanced Weathering): Spreading ground basalt on soil accelerates natural chemical weathering. Basalt reacts with atmospheric CO2 to form stable carbonates, effectively locking carbon in the soil and oceans for millennia.
- Activity 2 (Ocean Alkalinity Enhancement): Adding alkaline substances like lime (calcium oxide) to oceans neutralizes acidity and enhances the water's capacity to absorb CO2 from the atmosphere through chemical equilibrium.
- Activity 3 (Geological Sequestration): Pumping carbonated water (CO2 dissolved in water) into subterranean sites, such as basaltic formations or abandoned mines, facilitates "mineral carbonation." Projects like Iceland's Carbfix demonstrate that CO2 injected this way reacts with host rocks to turn into solid minerals.
Since all three techniques are actively discussed in climate mitigation strategies to reduce atmospheric greenhouse gas concentrations, Option 3 is the most comprehensive and accurate choice.
PROVENANCE & STUDY PATTERN
Guest previewThis question tests 'Frontier Climate Tech'—specifically Geoengineering and Carbon Dioxide Removal (CDR). It punishes reliance on static textbooks (which only cover basic afforestation/CCS) and rewards aspirants who track 'Climate Solutions' in science news (DownToEarth, The Hindu S&T, IPCC reports).
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
Web source
Presence: 4/5
"This “enhanced weathering” could theoretically increase CO2 sequestration in the ocean.
spreading finely ground alkaline substances over the open ocean"
Why this source?
- Explicitly uses the term “enhanced weathering” in the context of spreading finely ground minerals to increase CO2 sequestration.
- Describes the specific action of “spreading finely ground alkaline substances” as a method for increasing ocean CO2 uptake, showing enhanced-weathering concepts are discussed as carbon removal.
Web source
Presence: 4/5
"Principle of marine enhanced rock weathering (mERW) ... finely ground particles of a fast-weathering silicate mineral (e.g., olivine) are spread in the coastal zone."
Why this source?
- Describes marine enhanced rock weathering (mERW) where finely ground silicate minerals are spread in coastal zones to release alkalinity.
- Shows the enhanced-weathering approach (spreading ground silicates) is discussed as a means to enhance alkalinity and thus carbon sequestration — albeit in marine/coastal settings rather than farmland.
- Explicitly uses the term “enhanced weathering” in the context of spreading finely ground minerals to increase CO2 sequestration.
- Describes the specific action of “spreading finely ground alkaline substances” as a method for increasing ocean CO2 uptake, showing enhanced-weathering concepts are discussed as carbon removal.
- Describes marine enhanced rock weathering (mERW) where finely ground silicate minerals are spread in coastal zones to release alkalinity.
- Shows the enhanced-weathering approach (spreading ground silicates) is discussed as a means to enhance alkalinity and thus carbon sequestration — albeit in marine/coastal settings rather than farmland.
FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 5: Geomorphic Processes > Chemical Weathering Processes > p. 40
Strength: 5/5
“A group of weathering processes viz; solution, carbonation, hydration, oxidation and reduction act on the rocks to decompose, dissolve or reduce them to a fine clastic state through chemical reactions by oxygen, surface and/or soil water and other acids. Water and air (oxygen and carbon dioxide) along with heat must be present to speed up all chemical reactions. Over and above the carbon dioxide present in the air, decomposition of plants and animals increases the quantity of carbon dioxide underground. These chemical reactions on various minerals are very much similar to the chemical reactions in a laboratory.”
Why relevant
Describes chemical weathering processes driven by water, CO2 and acids that decompose rocks to finer material — establishing that weathering reactions involve atmospheric CO2.
How to extend
A student could combine this with the basic fact that some silicate rocks react with CO2 when weathered to infer that deliberately increasing rock surface area (grinding basalt) might increase CO2 uptake.
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 6: Geomorphic Movements > Chemical Weathering > p. 90
Strength: 4/5
“• Chemical weathering involves the chemical decomposition of rocks and soil due to the loosening of bonds between grains. The processes include dissolution, solution, carbonation, hydration, oxidation, and reduction. These weathering processes are interrelated and go hand in hand and hasten the weathering process.• Acids produced by microbial and plant-root metabolism, water and air (oxygen and carbon dioxide) along with heat speed up all chemical reactions.”
Why relevant
Explains that chemical weathering (including carbonation) is accelerated by water, CO2 and biological acids, implying weathering can be enhanced by environmental contact.
How to extend
One could extend this to ask whether spreading fine rock on soil increases contact with water/CO2 and therefore enhances CO2-consuming weathering reactions.
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > BiogEochEmical cyclEs. > p. 18
Strength: 4/5
“Te cycling, at various scales, of minerals and compounds through the ecosystem is known as biogeochemical cycle. Te cycles (carbon cycle and nitrogen cycle) involve phases of weathering of rocks, uptake and storage by organisms and return to the pool of the soil, the atmosphere or ocean sediments. Te biogeochemistry of carbon has attracted particular attention because of the concern of global warming and greenhouse efects.”
Why relevant
States that biogeochemical cycles include phases of weathering of rocks and that the carbon cycle is tied to weathering processes.
How to extend
A student might link this to the idea that altering the weathering phase (more reactive rock exposed) could influence carbon flow from atmosphere into minerals or soils.
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > carBon SInK. > p. 57
Strength: 3/5
“A carbon sink is anything that absorbs more carbon than that it releases, while a carbon source is anything that releases more carbon than is absorbed. Forests, soils, oceans, water-bodies, and atmosphere all store carbon and this carbon moves between them in a continuous cycle. Tis constant movement of carbon means that forests act as sources or sinks at diferent times. In other words, a carbon sink is natural or artifcial reservoir that accumulates and stores some carbon-containing chemical compounds for an indefnite period. Te artifcial sinks are (i) landflls, and (ii) carbon capture and storage proposals.”
Why relevant
Defines artificial carbon sinks and lists carbon capture and storage proposals as an approach to store carbon for indefinite periods.
How to extend
Use this to frame enhanced weathering as a candidate 'artificial sink' hypothesis to investigate in literature or policy discussions.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 21: Mitigation Strategies > zr.r.r. Sinks > p. 281
Strength: 3/5
“• r Carbon sequestration may be carried out by pumping carbon into'carbon sinks'* an area that absorbs cafbon. • r Natural sinks Oceans, forests, soil etc.• e Artificial sinks Depleted oil reserves, unmineable mines, etc.• r Carbon capture has actuaily been in use for years. The oil and gas industries have used carbon capture for decades as a way to enhance oi1 and gas recovery. Only recently have we started lhinking about capturing carbon for environmental reasons.”
Why relevant
Notes carbon capture/ sequestration is an established category of mitigation and that artificial sinks (besides natural ones) are considered strategies.
How to extend
This supports searching within carbon-capture topics for specific methods (e.g., enhanced weathering of rocks) as potential proposals under that umbrella.
Describes chemical weathering processes driven by water, CO2 and acids that decompose rocks to finer material — establishing that weathering reactions involve atmospheric CO2.
A student could combine this with the basic fact that some silicate rocks react with CO2 when weathered to infer that deliberately increasing rock surface area (grinding basalt) might increase CO2 uptake.
Explains that chemical weathering (including carbonation) is accelerated by water, CO2 and biological acids, implying weathering can be enhanced by environmental contact.
One could extend this to ask whether spreading fine rock on soil increases contact with water/CO2 and therefore enhances CO2-consuming weathering reactions.
States that biogeochemical cycles include phases of weathering of rocks and that the carbon cycle is tied to weathering processes.
A student might link this to the idea that altering the weathering phase (more reactive rock exposed) could influence carbon flow from atmosphere into minerals or soils.
Defines artificial carbon sinks and lists carbon capture and storage proposals as an approach to store carbon for indefinite periods.
Use this to frame enhanced weathering as a candidate 'artificial sink' hypothesis to investigate in literature or policy discussions.
Notes carbon capture/ sequestration is an established category of mitigation and that artificial sinks (besides natural ones) are considered strategies.
This supports searching within carbon-capture topics for specific methods (e.g., enhanced weathering of rocks) as potential proposals under that umbrella.
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