Concept:
Environmental chemistry studies the impact of chemical substances on living organisms and ecosystems. Many pollutants have well-defined toxicological effects such as carcinogenicity, organ damage, eutrophication, and skeletal disorders. Correct matching requires understanding these standard associations.
Step 1: Phosphates (A)
Phosphates mainly originate from fertilizers and detergents. When introduced into water bodies, they act as nutrients for algae, causing excessive algal growth known as eutrophication. This reduces dissolved oxygen and disturbs aquatic ecosystems.
\[
\text{Phosphates} \rightarrow \text{Enhances algae growth (III)}
\]
Step 2: PCBs (B)
Polychlorinated Biphenyls (PCBs) are persistent organic pollutants. They accumulate in the food chain and are widely recognized as toxic substances with suspected carcinogenic effects in humans.
\[
\text{PCBs} \rightarrow \text{Suspected to be carcinogenic (I)}
\]
Step 3: Lead (Pb > 50 ppb) (C)
Lead is a highly toxic heavy metal. At elevated concentrations in drinking water, it causes severe damage to vital organs, especially the kidneys, and also affects the nervous system.
\[
\text{Pb > 50 ppb} \rightarrow \text{Damage kidney (IV)}
\]
Step 4: Fluoride (F(^-) > 10 ppm) (D)
Excess fluoride in drinking water leads to skeletal fluorosis. It weakens bones, making them brittle and deformed.
\[
\text{F(^-) > 10 ppm} \rightarrow \text{Harmful to bones (II)}
\]
Final Matching:
\[
A \rightarrow III,\quad B \rightarrow I,\quad C \rightarrow IV,\quad D \rightarrow II
\]
Thus, the correct option is (D).
