Lead, Zinc, and Manganese, in Dredge-spoil Pond Ecosystems

Abstract

Pb, Zn, and Mn, levels in sediment and common estuarine plants and animals colonizing dredge-spoil disposal areas were compared with levels occurring in the same materials from a natural salt-marsh. Finegrained dredge-spoil had considerabily higher levels of all three metals than did natural salt-marsh sediment, and large differences in the metals content of the spoil were observed, depending on sediment type.Pb levels in the Grass Shrimp (Palaemonetes pugio), Mummichog (Fundulus heteroclitus), Common Reed (Phragmites communis), Saltmarsh Cordgrass (Spartina alterniflora), and Saltmeadow Hay (Spartina patens), from dredge-spoil areas, were significantly higher at the 0.01 confidence level than in these species from the natural salt-marsh. Zn concentrations were significantly higher at this confidence level in the three plant species growing in dredge-spoil compared with those from the natural marsh. Mn content in Grass Shrimp from ponds in dredge-spoil disposal areas was significantly higher (0.05 confidence level) than in those from the natural marsh. Thus, dredge-spoil containing heavy metals, even though disposed of in specially designed diked containment areas, may act as a source of certain heavy metals that are potentially toxic to the biota.Data on the transfer of Pb and Mn in simple foodchains of the dredge-spoil pond ecosystem are presented and discussed in relation to feeding behaviour. Decreasing concentrations with increasing tropic level were observed for Pb and Mn, but no consistent pattern was noted with Zn.

Dredged materials–problems associated with their use on land

“…This demonstrates that in considering the environmental consequences of metal uptake, conditions within the animal, in addition to detailed speciation studies of metals in the soils, grass or water, have to be taken into account. In a similar study, Pb and Mn also tended to decrease markedly with increasing trophic level in both detritus-based, and grazing food chains in a dredge spoil pond, but no consistent pattern was observed in the case of Zn (Drifmeyer & Odum, 1975). However, on several occasions in this study, higher consumers such as mating shore birds and migratory wildfowl were observed feeding in the spoil pond, and thus the dredge spoil may have been a source of certain heavy metals that are potentially toxic to higher trophic organisms; consideration of the problems should, therefore, not be confined solely to domestic animals.…”

Pollutant transport in wetlands. Marshes, bogs, or other types of wetland prove to be excellent receivers for the disposition of treated wastewaters containing small amounts of dissolved nitrogen and phosphorus

“…Many investigators have reported that heavy metals are often closely associated with sediments and upper-soil horizons [22], [23], [24], [25]. Actual measurements of equilibrium uptakes in wetlands are difficult to obtain.…”

On the transfer of several trace elements in neritic and estuarine food chains: Bioaccumulation in omnivorous and carnivorous fishes

“…Les donn6es de la litt6rature r6sultant soit de mesures in situ de la concentration des m6taux en fonction du niveau trophique des organismes, soit d'exp6riences de contamination des organismes par voie alimentaire, confirment que s'il y a une bioaccumulation* non n6gligeable de Cd, Pb et Cu chez les organismes aquatiques, il n'y a vraisemblablement pas biomagnification" * dans les r6seaux alimentaires (Bohn & Mc Elroy, 1976;Aubert et al, 1972Aubert et al, , 1974Aubert et al, , 1975Aubert et al, , 1976Drifmeyer & Odum, 1975;Rehwoldt et al, 1978;Hodson et al, 1978;Steele et al, 1973).…”