Fill in the blanks with suitable words :

1. Increase in concentration of soluble salts in the soil is called.........

2. Aforestation can check the advancement of......... .

3. DDT is a serious pollutant as it is a.........pollutant and undergoes......... .

4 .........plant has become a troublesome weed in agricultural fields.

5 .........are major aerosol pollutant present in jet aircraft emission.