Final answer:
The specific concentration of DDT in the blackbird cannot be calculated without information on the biomagnification factor, but biomagnification leads to increasing concentrations up the food chain, potentially leading to the thrush's death if above toxic thresholds.
Step-by-step explanation:
The calculation of the concentration of DDT in the body of a blackbird from the information given in the question cannot be provided directly as the question does not supply the biomagnification factor necessary to determine the increase in concentration from the leaves to the bird. The biomagnification process refers to the increasing concentration of substances such as DDT in organisms as it moves up the food chain. Without knowing at which trophic level the blackbird feeds and the concentration of DDT at every level through which it has passed, the exact concentration in the blackbird cannot be calculated.
However, we can surmise from the given data that since the ground value of DDT is 0.07 mg/kg in the leaves, it would typically become more concentrated as it goes up the food chain. If it exceeds the guideline DDT concentration (GDK DDT) of 0.100 mg/kg, which could be the threshold for toxic effects, it could have led to the death of the bird. Since the thrush died, it suggests that the concentration in its body was above the GDK DDT due to biomagnification.
A further example of biomagnification's impact on bird populations is the thinning of eggshells, which leads to breakage during nesting. The consequence of such biomagnification was heavily documented in Rachel Carson's Silent Spring, which contributed to the ban of DDT in the United States in the 1970s.