Some More Good News: Recovery Suprisingly Fast for Mercury-Plagued Fish
by Jeremy Elton Jacquot, Los Angeles on 09.18.07
Though you'll probably still want to pass on the contaminated fish from this river, the good news is that you can rest assured that the levels of the toxic metal in the fish and other organisms will - if contained - decrease in short order. A team of scientists from British Columbia found that limiting the amount of mercury emissions from sources such as power plants could result in the rapid decontamination of fish populations within a period of years.
In their study, the researchers artificially increased the levels of mercury in a lake ecosystem in western Ontario by adding an inorganic and less toxic form of mercury. They spent the ensuing 7 years monitoring the levels of mercury in the food chain, focusing in particular on the lake's top predator, the northern pike. They discovered that the majority of the mercury absorbed by the northern pike population came from the amounts they added to the lake; this led them to conclude that eliminating the mercury from power plant emissions - the primary source of the metal entering the lake ecosystem - would greatly contribute to the aquatic life's rapid decontamination.
John Rudd, a biogeochemist and co-author of the study, said the next part of the experiment will consist of halting the addition of mercury to the lake and monitoring the metal's concentrations in the lake's organisms. In addition to demonstrating the speed with which mercury levels can build up within the bodies of fish, James Wiener - an aquatic toxicologist at the University of Wisconsin, La Crosse - stresses the study's significance in showing "the probable effectiveness of reducing emissions." No arguments there.
UPDATE: As JL notes in the comments, the significance of this study shouldn't be hastily extrapolated to other bodies of water; the particular lake ecosystem's features may have been in large part responsible for the results (time will tell). Also, the results certainly shouldn't imply that big businesses and industry interests go ahead and upp their mercury use by arguing that decontamination occurs rapidly.
Reducing emissions is key; the study's larger implications should be viewed in the context of future research on the subject.
Via ::ScienceNOW: Fish Quick to Recover From Mercury (news website)
See also: ::One in Every Four New Yorkers Has Elevated Blood Mercury Levels, ::Got Mercury? Here is a Calculator to Figure it Out
Image courtesy of redjar via flickr
Unless the peer review of this work included se4asoned geo-hydrologists and limnologists, I suggest not extrapolating the findings very far at all. An over arching speculation based on a one-off study like this one give the industry funded Think Tanks and nutty talk show hosts the ammunition they love to have to claim that environmentalists have "once again" been proven wrong: e.g. the erisk of coal burning impacts can be easily overcome. This feeds right into the "fund "Clean Coal" now" talking point. Here is the substance of my concern:
Some lakes get almost all their inflow from surface water runoff, some mostly from groundwater, some by river inflow, which reflects both ground and surfce runoff, and others by a combination of surface runoff, groundwater, and river inflow.
Some watersheds have surficial soils that are highly contaminated from decades of coal-caused mercury deposition; and that mercury ican be mobilized toward the lake by erosion and by acid rain. Acid rain soluablizes mercury, enabling it to move through groundwater. Not all watersheds are equally impacted by acid rain. And not all lakes recieve water in a similar way, nor is "replacement time" similar among lake volumes. Hence, an extrapolation fo these findings to the class of "all lakes," as inferred, is absurd.
Moreover, some lakes have very high mercury levels in sediments and those sedimentary mercury contents may either be manily sequestered or partly recycled to the water column anda food chain, depending on physical and biological characteristics of the specific lake in question.
Finally, anaerobic processes in lake sediments convert inorganic to organic mercury forms. Do not the authors realize this? The meaning of this work should not be extrapolated beyond the single setting studied