Unit 5

• Reclamation of Alkaline Soils: Decomposing organic compost produces organic acids (humic acid, fulvic acid) and carbonic acid ($\text{H}_2\text{CO}_3$), which dissolve native calcium carbonate ($\text{CaCO}_3$) to release soluble calcium ions ($\text{Ca}^{2+}$).
• Leaching of Displaced Salts: Solubilized $\text{Ca}^{2+}$ exchanges with sodium ($\text{Na}^+$) on the exchange complex. The improved soil aggregation and macroporosity allow excess salts and sodium to be leached and washed away below the root zone with irrigation water.

Correct option: (1) Wash away salts and chemicals

• Cradle-to-Grave Principle: Under the Hazardous and Other Wastes (Management and Transboundary Movement) Rules and international environmental frameworks, the primary legal responsibility for safe characterization, containment, packaging, and disposal rests with the Generator.
• Role of TSDFs: Treatment, Storage, and Disposal Facilities (TSDFs) act as authorized operational service providers, but legal compliance and chain of custody originate from the generator.

Correct option: (1) Generator

• Carbon Pools in Indian Forests (ISFR-2021):
• Total carbon stock in Indian forests is estimated at $7,204\text{ million tonnes}$.
• Distribution across carbon pools:
• Soil Organic Carbon (SOC): Represents the largest single pool, accounting for $\approx 56.1\%$ ($4,010\text{ Mt}$).
• Above-ground + Below-ground biomass: Accounts for $\approx 41.1\%$ ($2,961\text{ Mt}$).
• Litter: $\approx 1.8\%$ ($180\text{ Mt}$).
• Dead Wood: Accounts for the smallest fraction, $\approx 0.6\%$ ($46\text{ Mt}$).
• Correct Sequence: Soil organic carbon > above + below ground biomass > litter > dead wood. (Correct answer: Option 4)