Some of these compounds, as Dr. Gray mentioned, are biodegradable, but this makes for some interesting challenges in the tailings ponds when they do biodegrade. We all think that these ponds are dead and there's nothing there, but micro-organisms exist everywhere, and they exist in those tailings ponds. And it's been noticed that with the addition of certain of these compounds, when the micro-organisms that actually exist in these tailings ponds are degrading, they produce gases. Some of these gases—such as methane, when it starts to be generated in the tailings ponds—actually help densification, so the tailings settle faster. However, you do have tailings ponds producing methane and some other gases.
