Two recent events - the debate over nafta and a gatt dispute settlement panel recommendation against the us imposition of a trade ban against mexican tuna imports to support us dolphin protection efforts - have catapulted the previously arcane trade and environmentalists paid little attention to trade issues 二个最近的事件，是关于nafta的辩论和gatt争执解决研究小组提出反对一个美国的商业禁令反对墨西哥鲔鱼的进口，以支援美国海豚保护的努力成果，对于以前不可思议的贸易方式，环境保护者对于商业问题开始有了关注。
And just because a region receives above - average deposition doesn ' t mean that it will have high levels of methyl mercury , the form that builds up in long - lived predatory fish such as trout , pike , tuna and swordfish . “ the areas with the most problems may not have the highest levels of deposition , ” explains mercury expert david krabbenhoft of the u . s 而且某一地区不会因为承受的汞沉降高于平均值，就表示该处也会有较高浓度的甲基汞，这种形式的汞会在寿命较长的掠食鱼类体内逐渐堆积，如鳟鱼、狗鱼、鲔鱼和旗鱼等。
