Bioaccumulation and Biomagnification of Radiocesium in Littoral Zone Biota

from a Cooling Reservoir on the Savannah River SiteChristina Fulghum1, 2, Alexis Korotasz1, 3, Larry Bryan1

1Savannah River Ecology Laboratory, Aiken, SC 29802, 2University of South Carolina - Aiken, Aiken, SC 29801, 3Stetson University, DeLand, FL 32723

CONCLUSIONS AND DISCUSSION

• We did not find any overall spatial accumulation patterns. There were a few differences, but no

consistent trends for one site being significantly higher in radiocesium than the other sites.

• We did find the biota to still be accumulating radiocesium after more than 50 years since the original

contamination of Pond B.

• As for biomagnification, it may increase for some linkages, but there were no consistent trends overall.

Our length vs radiocesium data did not support biomagnification within species.

• We recommend an expansion of the research to include the entire lake and possibly the inclusion of

stable isotope analyses to quantify trophic structure.

Acknowledgements: This research was funded through the National Science Foundation’s Radioecology

Research Experience for Undergraduates program hosted at the Savannah River Ecology Lab (UGA) and

the Department of Energy.

STUDY AREA

Pond B - Savannah River Site

• Pond B was first filled in 1961 with

cooling water discharge from R

reactor.

• Pond B continued to receive effluent

from R Reactor until 1964.

• Past studies done by Whicker et al

and Newman and Brisbin looked at

radiocesium levels in selected aquatic

biota from Pond B and found

radiocesium to bioaccumulate.

• Three sites on Pond B were sampled

based on their characteristics and

location relative to presumed water

flow.

Figure 1. Map of the Savannah River Site indicating Pond B and the three study

sites: Inflow canal, Island, and outflow canal

Outflow

canalInflow

canal

Island

• The inflow and outflow canals are in the direct flow of water entering in from and exiting

out to R canal. We chose to examine the inside of the inflow canal (which is the end of R

canal) separate from the outside of the canal. We also chose Heron Island because it is

north of the presumed main water flow.

• We focused on biota from the littoral zone.

METHODS

• We collected 3 sediment samples from each site.

• To sample biofilms, we placed two floating PVC frames, each with four large plexiglas plates, at

each of the sites for 30 days. Then the plates were scraped down into tubes.

• We collected fish samples by setting 10 or more minnow traps at each of the sites along the

shoreline and collected samples from these for 23 days and also dip-netted for smaller fish and

invertebrates.

• After being measured and weighed, all of the organisms collected were also frozen.

• All samples were then freeze-dried, ground up and packed into tubes.

• Each sample tube was counted in an auto gamma counter for an hour to obtain radiocesium levels.

• Statistical analyses involved a Kruskal-Walis analysis (among groups) and a Dunn’s test (for

pairwise comparison).

INTRODUCTION

Background

• 137Cs, or Radiocesium, is a radioactive isotope that is produced as a byproduct of nuclear fission.

• Radiocesium behaves like potassium when it enters the body and accumulates in muscle and soft

tissue.

• It is of particular concern because it is long-lived (30.17 year half-life) and easily absorbed into body

tissues so contaminated fish pose a potential health risk for higher trophic level wildlife.

• Past studies have shown radiocesium to bioaccumulate in biota from aquatic systems.

Objectives

1. Determine radiocesium (137Cs) levels in littoral zone biota from Pond B with

legacy contaminants and assess if biomagnification occurs

2. Assess if spatial heterogeneity in radiocesium levels occur among

species or sites.

RESULTS

Figure 4. Average 137Cs among biofilm and all species from the

combined main pond. Error bars represent + 1 standard .

Figure 5. 137Cs concentrations relative to fish length for three species of fish on Pond B.

Figure 3. Average 137Cs in sediments and biofilm at each study

area. Error bars represent + 1 standard error.

We collected four fish species and one benthic invertebrate species (Fig 2).

We analyzed the sediment and biofilm samples to determine the base level of radiocesium in the system

(Fig 3) and found little difference among sites.

Next we compared radiocesium levels of individual species among sites and found few differences:

• Mosquitofish – Island > Inside of inflow canal

• Dragonfly larva – Island > Outflow canal

• No significant differences were found with the bluegills, warmouths, and redfins

We then examined all species within each site. The outflow was the only area with a significant difference.

• Bluegill >dragonfly larvae (neither species different from other biota)

Overall there were no consistent spatial patterns for radiocesium accumulation.

Because of the lack of spatial heterogeneity, we combined the main pond sites (all sites except for the

inside of the inflow canal) samples to increase sample sizes and again examine for species differences

within the entire system (Fig 4). Redfin pickerel and Bluegill were > biofilms and dragonfly larvae.

To examine for potential size/age effects in radiocesium accumulation, we analyzed fish lengths relative to

radiocesium levels for all bluegills, warmouths, and redfins (all sites combined). We found significant but

weak correlations for all three species (Fig 5), but not consistent trends.

Figure 2. Biota collected for four sites in the littoral zone of Pond B.

LITERATURE CITED

• Newman, Michael C., and I. Lehr Brisbin. "Variation of 137Cs levels between sexes, body sizes and

collection localities of mosquitofish, Gambusia holbrooki (Girard 1859), inhabiting a reactor cooling

reservoir." Journal of Environmental Radioactivity 12.2 (1990): 131-141.

• Whicker, F. Ward, et al. "Distribution of Long‐Lived Radionuclides in an Abandoned Reactor Cooling

Reservoir." Ecological Monographs 60.4 (1990): 471-496.