Title: Metal accumulation in dragonfly nymphs and crayfish as indicators of constructed wetland effectiveness

Abstract

Constructed wetland effectiveness is often assessed by measuring reductions of contaminant concentrations in influent versus departing effluent, but this can be complicated by fluctuations in contaminant content/chemistry and hydrology. We assessed effectiveness of a constructed wetland at protecting downstream biota from accumulating elevated metal concentrations—particularly copper and zinc in effluents from a nuclear materials processing facility. Contaminants distributed throughout a constructed wetland system and two reference wetlands were assessed using six dragonfly nymph genera (Anax, Erythemis, Libellula, Pachydiplax, Tramea, and Plathemis) as biomonitors. Additionally, the crayfish, Cambarus latimanus, were analyzed from the receiving and two reference streams. Concentrations of Cu, Zn, Pb, Mn, Cr, Cd, and Al were evaluated in 597 dragonfly nymph and 149 crayfish whole-body composite samples. Dragonfly genera varied substantially in metal accumulation and the ability to identify elevated metal levels throughout components of the constructed wetland. Genera more closely associated with bottom sediments tended to accumulate higher levels of metals with Libellula, Pachydiplax, and Erythemis often accumulating highest concentrations and differing most among sites. This, combined with their abundance and broad distributions make the latter two species suitable candidates as biomonitors for constructed wetlands. As expected, dragonfly nymphs accumulated higher metal concentrations in the constructed wetlandmore » than reference sites. However, dragonfly nymphs often accumulated as high of metal concentrations downstream as upstream of the water treatment cells. Moreover, crayfish from the receiving stream near the constructed wetland accumulated substantially higher Cu concentrations than from downstream locations or reference streams. Despite reducing metal concentrations at base flow and maintaining regulatory compliance, metal fluxes from the wetland were sufficient to increase accumulation in downstream biota. Future work should evaluate the causes of downstream accumulation as the next step necessary to develop plans to improve the metal sequestering efficiency of the wetland under variable flow regimes.« less

Authors:

Fletcher, Dean E. ^[1]; Lindell, Angela H. ^[1]; Stankus, Paul T. ^[1]; Fletcher, Nathaniel D. ^[1]; Lindell, Brooke E. ^[1]; McArthur, J. Vaun ^[1]

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+ Show Author Affiliations

1. Savannah River Site (SRS), Aiken, SC (United States). Savannah River Ecology Lab. (SREL)

Publication Date:

Tue Oct 22 00:00:00 EDT 2019

Research Org.:

Univ. of Georgia, Athens, GA (United States)

Sponsoring Org.:

USDOE Office of Environmental Management (EM); USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1799580

Alternate Identifier(s):

OSTI ID: 1579436

Grant/Contract Number:  

EM0004391

Resource Type:

Accepted Manuscript

Journal Name:

Environmental Pollution

Additional Journal Information:

Journal Volume: 256; Journal ID: ISSN 0269-7491

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.; constructed wetland; bioaccumulation; metal; biomonitor; aquatic invertebrates