Air is then breathed into the windpipe and lungs, while the mucus is swallowed (figure 3). Other. Other interesting structures associated with the nasal and sinus tract: Tear duct (called the nasolacrimal duct): drains tears from the inside corner of the eye into the nasal cavity (figure 1).
Human activity is the main cause of soil degradation. Agriculture plays a large part in soil degradation, especially clearing, irrigation, the spreading of chemical fertilizer â¦ s and pesticides, overgrazing and even the passage of heavy farming equipment. Tillage and the clearing and deforestation of large plots of land also lead to soil degradation.
6 The Pardee Papers | No. 15 | August 2011 c. Land degradation: Land degradation due to soil erosion and salinity (among other factors) is also a problem. It is estimated that about 30 percent of agricultural land in Africa is already degraded (ECA 2004). For some countries, this degradation has already reached alarming proportions.