CEINT Mesocosms in the Duke Forest, an update

Situated in the forest away from campus, it can be easy to forget the work and research continually ongoing at the CEINT Mesocosm Facility. With experiments out in the Duke Forest Teaching and Research Laboratory lasting a year or longer, monitoring, sampling and data analysis is a continual process, undertaken by a number of labs long after the initial flurry of setup and initiation of treatments takes place. Then, at the end of an experiment cycle, things kick into high gear again as the final samples are collected and each mesocosm’s biota is harvested for analysis.

Recently, members of CEINT from Duke and Baylor finished a round of experiments designed to compare the impacts of silver nanoparticles added either as an acute one-time “pulse” or a chronic weekly “press” addition. In both scenarios, the same total amount of NPs was added to each mesocosm at 450 mg. The different exposure scenarios and duration of the experiment allowed CEINT researchers to investigate the short- and long-term impacts in the transport of the NPs from the water column into the sediment, the biota, and up into the food chain of a complex ecosystem.

From this 52-week experiment, investigators are seeking to answer the question of where the nanoparticles end up and what impacts they might have along the way. To help nail this down, they’re investigating both ecosystem pools and bioreceptors, monitoring conditions and periodically taking samples from the mesocoms. The major sampling effort for the final time point took just over a week and included harvesting algae, plants, and animals ranging from microscopic plankton to macroscopic fish and fishing spiders. In addition to looking at organism abundance and uptake of silver, behavioral assays of the harvested clams and snails were performed in which researchers tracked the snails’ speed and distance covered and the clams’ ability to bury themselves. These data will be coupled with enzyme assays to determine if any link exists between treatment, behavior and stress.

The mesocosms employed for this recently finished experiment will be reset for the next round of experiments--a process that includes removing and replacing all the soil and water and then repopulating the biota. Meanwhile, there are several other investigations in process headed up by researchers at Carnegie Melon, Virginia Tech, and Duke, ensuring that the work continues out in the forest.

For more information about previous research performed with CEINT’s mesocosm facility, see the following:

Lowry, Gregory V., et al. Long-term transformation and fate of manufactured Ag nanoparticles in a simulated large scale freshwater emergent wetland. Environmental science & technology 46.13 (2012): 7027-7036.

Colman BP, Espinasse B, Richardson CJ, Matson CW, Lowry GV, Hunt DE, Wiesner MR, Bernhardt ES.  2014.  Emerging Contaminant or an Old Toxin in Disguise? Silver Nanoparticle Impacts on Ecosystems Environmental Science & Technology. 48(9):5229-5236.

Colman BP, Arnaout CL, Anciaux S, Gunsch CK, Hochella MF, Kim B, Lowry GV, McGill BM, Reinsch BC, Richardson CJ et al..  2013.  Low Concentrations of Silver Nanoparticles in Biosolids Cause Adverse Ecosystem Responses under Realistic Field Scenario. PLoS ONE. 8(2):e57189.