In an aquatic food chain, if water is having 0.003 ppb of DDT can reach upto 25 ppm in

Options

A. Large fish
B. Phytoplanktons
C. Fish eating birds
D. Small fish

Answer

To solve the problem regarding the concentration of DDT in an aquatic food chain, we will follow these steps:

### Step 1: Understand the Initial Concentration
The initial concentration of DDT in water is given as 0.003 ppb (parts per billion).

### Step 2: Convert ppb to ppm
To understand how this concentration can increase, we need to convert ppb to ppm (parts per million).
1 ppb is equivalent to 0.001 ppm. Therefore, to convert 0.003 ppb to ppm:
\[ 0.003 \, \text{ppb} \times 0.001 \, \text{ppm/ppb} = 0.000003 \, \text{ppm} \]

### Step 3: Understand Biomagnification
Biomagnification is the process where the concentration of a toxic substance increases at each trophic level in a food chain. As organisms at lower levels are consumed by those at higher levels, the concentration of the toxicant accumulates.

### Step 4: Identify Trophic Levels
In the aquatic food chain, the following trophic levels can be identified:
1. **Phytoplankton** (primary producers)
2. **Small Fish** (primary consumers)
3. **Large Fish** (secondary consumers)
4. **Fish-eating Birds** (tertiary consumers)

### Step 5: Estimate Concentration at Each Trophic Level
As we move up the food chain, the concentration of DDT increases. The question states that it can reach up to 25 ppm in fish-eating birds. This indicates a significant accumulation through the food chain.

### Step 6: Conclusion
Thus, starting from a concentration of 0.003 ppb in water, through the process of biomagnification, DDT can reach concentrations as high as 25 ppm in fish-eating birds, which are at the top of the food chain.

### Summary
- Initial concentration of DDT in water: 0.003 ppb
- Conversion to ppm: 0.000003 ppm
- Through biomagnification, concentration increases at each trophic level, reaching 25 ppm in fish-eating birds.

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