from ththe "exxon v valdez" o or abot the recent spill in the gulf of mexico that brititish petreum mn illing provokeked. you're talking about a whole differenent set of problems. how do they compmpare with thosese big spills? micah: it's a great question. i think we all get our attention awn to the big dramatic moment. explosion of an oil rig, the sinking of a giant oil tanker. but in fact, over time, if you look at the total cumulative effect of that, it's only about 20% of the oil that goes into the ocean frfrom human sources. the much larger component is this relar, everyday, intentional dumping overboard, getting rid of oil, waste products, sludge. ships--commerciaial ships tend o burn very low-grade oil, and thatat produces this messy slud. and the question is, what do you do w with that? well, by law, you're supposed to bring it to port, you're supposed to offload it. it takes t time, it takes money, it takes energy to properly dispose of this stuff. or, if you're not trying to obey the law,ou can jusust dump it overboard, which the shippers believe save them time and money. mariners traditionall