Scientists just found an underground river leaking mercury into Spain’s Mar Menor lagoon—yep, a literal toxic river! This hidden flow dumps about 2.2 pounds of mercury every year, and it’s not new pollution, but leftover stuff from old mining and farming. The wild part? The mercury mixes with lagoon water and turns into methylmercury, which builds up in fish and could mess with the whole ecosystem. Even if we stop new pollution, this underground leak could keep going for ages. Wild, right? #Science #MarMenor #Mercury