For decades, something in urban streams has been killing coho salmon in the U.S. Pacific Northwest. Up to 90% of the adults migrating up certain streams to spawn suddenly die after rainstorms. Researchers report online in Science that the primary culprit comes from a chemical widely used to protect tires from ozone, a reactive atmospheric gas. The toxicant, called 6PPD-quinone, leaches out of the small particles that tires shed onto pavement. Even small doses killed coho salmon in the lab. The researchers suspect the compound is present on busy roads everywhere. The simplest solution might be for tire manufacturers to switch to an environmentally benign alternative. Another way to protect salmon is to filter stormwater through soil, but installing enough infiltration basins to treat road runoff before it reaches spawning streams would be very expensive.

几十年来，城市溪流中的某些东西一直在杀死美国太平洋西北部的银大麻哈鱼。高达90％的成年人在暴雨过后迁移到某些溪流以产卵，突然死亡。研究人员在线发表《科学》杂志罪魁祸首来自一种广泛用于保护轮胎免受臭氧破坏的化学物质。有毒物质称为6PPD醌，会从轮胎掉到人行道上的细小颗粒中浸出。即使是小剂量，在实验室中也会杀死银大麻哈鱼。研究人员怀疑这种化合物存在于世界各地繁忙的道路上。对于轮胎制造商而言，最简单的解决方案可能是转向环保的替代方案。保护鲑鱼的另一种方法是通过土壤过滤雨水，但是安装足够的渗透池在道路径流到达产卵流之前对其进行处理将非常昂贵。