> Mercury is a common by-product of gold mining, a growing industry in several southern countries. The toxic metal accumulates as it moves up the food chain by binding with amino acids in animals and then infiltrating their central nervous systems, where it can inhibit neural growth. Tracking mercury exposure is crucial for monitoring an ecosystem—but merely sampling rocks, ice or soil for its presence tells little about how much is actually entering the food web.<p><a href="https://archive.is/Ksx0p" rel="nofollow">https://archive.is/Ksx0p</a>