David Tsao
HH: So many pollutants are new to nature or occur in unnaturally large concentrations. Are you surprised that plants can help clean them up?
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DT: Not necessarily. Phytoremediation is sometimes like a black box: we can measure what’s there before and we can measure what’s there afterwards, but we don’t always know what happens in between. In a way, I don’t care how it works as long as it does work. But some regulators want to know how it works to make sure it won’t make things worse.
HH: Is it possible to change your tools with genetic engineering?
DT: It’s generally approved of, since even when it doesn’t help it usually won’t hurt. One major regulatory concern is whether we might impact the food web. Some newly published research, for instance, shows that pumpkins are very good accumulators of DDT–but that poses a problem if small creatures eat the pumpkins and are themselves eaten by larger animals, in which case the DDT returns to the environment. And there are limits to the technology: roots only go so deep, their growth and activity depend on daily and seasonal cycles, and they can take a long time both to grow and do the job.
