The Text
The State shall protect and improve the environment and safeguard the water, air and land, forest and wild life of Nigeria.
Source · Constitution of the Federal Republic of Nigeria, 1999, as amended · §20
All sections in Chapter II — Fundamental Objectives and Directive Principles of State Policy
Methodology
Tier 1 · primary
Courts. Gazettes. National archives.
Tier 2 · corroborating
OCCRP. HRW. BudgIT. TheCable.
Redline
Wikipedia is never a source.