Blends of polyblend and bitumen, when used, help to increase road life by a factor of three. What is the reason?
Polyblend is a fine powder of recycled modified plastic. The binding property of plastic makes the road last longer besides giving added strength to withstand more loads.
This is because
(i) Plastic increases the melting point of the bitumen which would prevent it from melting in India's hot and extremely humid climate, where temperature frequently cross $50^{\circ} \mathrm{C}$.
(ii) Rainwater will not seep through because of the plastic in the tar.
Name an industry which can cause both air and thermal pollution and as well as eutrophication.
Chemical fertiliser unit, thermal power plant, refineries, smelting and metallurgical processing units steel mills, and the industries using steam or water as coolant causes both air and thermal pollution. The chemical release form these Industries (if rich in nitrogen and phosphorus) may result in eutrophication.
What is an algal bloom?
The extensive growth of planktonic (free-floating) algae in water bodies due to the presence of organic matter in water (cnitrogen and phosphores) that acts as a food source is called an algal bloom. This imparts a distinct colour to the water bodies.
What do you understand by biomagnification?
Biomagnification refers to the increase in the concentration of the toxic substances at successive trophic level Is in the food chain.
This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted and when this organism is eaten up by another animal of higher trophic level, it is passed on to this and then to the next higher trophic level and so on.