<span>One of the reasons PCB's have been hard to clean up from the puget sound is because they stay in the food chain. Once something is inside an animal it becomes much harder to remove from the environment than if it was just in water.</span>
Answer:
everyone was skeptical of each other's work and findings and they wanted to do their own research. Also, there has been a bunch of technological advances over the years. microscopes became better and stronger as well
Explanation:
Diffusion because it will go from high areas of concentration to areas of low concentration
It must be man-made and organic
