Commission on the present topic, th:, square brackets in the exprassior just quoted indictrt.8 that. the <ommission hns deferred the question of t.he use of the tbrm “system” . Sac footnote 128, above. 1421 Article 192, entitled “General obligation”, provides: “States have t.hv obl igwt:ion t.o protect. And preserve the mRr ins environment.. ” - 147 -to areas outside the watercourse, which is of course not the intention of the Commiolsion. For these reasons, the Commission preferred to utilisa the term “ecosystem”, which is believecl to have a more preaise scientific and legal meaning. M/ Qeuerally, that term refers to an ecologioal unit consisting of l&vinq and non-living components that are interdependent and function as a conununi ty .M/ “In ecosystems , everything depends on everything else and nothing is really wasted. ‘I M/ Thus, “[a)n external impact affecting one component of an ecosystem causes reactions among other components end may disturb the equilibrium of the entire ecosystem”. m/ Since “[e)cosystems support life on earth”, M/ such an “external impect”, or interference, may impair or destroy the ability of an ecosystem to function as a life-support sys tern. It goes without saying that serious interferences can be, and often are, brought about by human conduct. Human interferences may irrcversfbly disturb the equilibrium of freshwater ecosystems, in perticular, rendering tbsm incapable of aupportinq human and other forms of life. As observed in the Proposed Medium-Term Plan of the United Nations for the period 1992-19971 kw Reference may be made generally in this connection to the ongoing work of the Economic Commfssfon for Europe in this field. See “Ecosystems approach to water management” (ENVWA/WP.3/R.7/Rev.l), and the case studies on the Oulujoki River (Finland), Lake Mjosa (Norway), the Lower Rhine River (Netherlands), and the Ivankovskoye Reservoir (Soviet Union) (ENVWA/WP,J/R,ll/Add*1 sad 2).
**Analysis**
The text discusses the importance of preserving ecosystems and the potential impact of human activities on them. It quotes an article that emphasizes the obligation of states to protect and preserve the environment, and provides examples of freshwater ecosystems that have been affected by human activities. The text also references ongoing work by the Economic Commission for Europe on the "ecosystem approach to water management". Based on this, it seems that the text is primarily focused on environmental issues, particularly the protection of ecosystems and the management of natural resources.

**Category**
Natural resources and environment, Science and technology