Animated Solution for Chemistry - Environmental Chemistry: The concentration of fluoride, lead, nitrate and iron in a water sample from an underground lake was found to be $1000\mathrm{ppb}$, $40\mathrm{ppb}$, $100\mathrm{ppm}$ and $0.2\mathrm{ppm}$, respectively. This water is unsuitable for drinking due to high concentration of

Have you ever wondered what exactly is in the water you drink? It might look crystal clear, but at the microscopic level, it's a complex soup of ions and minerals. Some of these are essential for our health, while others can be incredibly dangerous if their concentrations cross a certain threshold.

In this problem, we are acting as environmental chemists. We have a water sample from an underground lake, and we've been given the concentrations of four specific components: fluoride, lead, iron, and nitrate. Our mission is to identify which of these is making the water unsuitable for drinking. To do this, we need to compare the given values with the maximum permissible limits set by health organizations like the WHO.

Let's break down the suspects one by one. First up is fluoride. The sample contains $1000\mathrm{ppb}$ (parts per billion) of fluoride. Now, $1000\mathrm{ppb}$ is exactly equal to $1\mathrm{ppm}$ (part per million). The permissible limit for fluoride in drinking water is up to $1.5\mathrm{ppm}$. Since $1\mathrm{ppm}$ is well within this limit, fluoride is not the problem here. In fact, a small amount of fluoride is often added to water to prevent tooth decay!

Next, we look at lead. The concentration given is $40\mathrm{ppb}$. Lead is a heavy metal and is highly toxic, so its permissible limit is very low—around $50\mathrm{ppb}$. Since our sample has $40\mathrm{ppb}$, it is just below the danger mark. So, lead is cleared of the charges.

What about iron? The sample contains $0.2\mathrm{ppm}$ of iron. The maximum allowable limit for iron is also $0.2\mathrm{ppm}$. It's right on the borderline, but technically, it hasn't crossed the limit. So, iron is safe for now.

Finally, we come to nitrate. The sample has a whopping $100\mathrm{ppm}$ of nitrate. Let's check the rulebook. The maximum permissible limit for nitrate in drinking water is only $50\mathrm{ppm}$.

Our sample has exactly double the allowed amount! This is a massive red flag. Excess nitrate in drinking water is extremely dangerous, especially for infants. It can lead to a condition called methemoglobinemia, commonly known as "blue baby syndrome," where the blood loses its ability to carry oxygen effectively.

Therefore, the high concentration of nitrate is the sole reason this water is completely unsuitable for drinking. By knowing these standard limits, we can literally save lives!