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.
With these processes combined, around 12 million hectares of productive land become barren every year due to desertification and drought alone (UNCCD, 2014). Which regions are affected? Desertification is a major problem across the world, most notably in dryland areas (including large areas in Africa, such as the Sahel. About 40% of Earthâs land is covered by drylands, and these areas are home to over 2 billion people.