Carbon flow in four lake ecosystems: a structural approach.

Direct and indirect carbon fluxes in lakes Marion (British Columbia), Findley (Washington), Wingra (Wisconsin), and Mirror (New Hampshire) are compared, using budgets and input-output analysis. Overall differences in carbon flow between the lakes are shown with cycling indices of .031, .108, .572, and .661, respectively. The results suggest that lake ecosystems may be considered unique aggregatins of similar components.

Sorption of pollutants by plant detritus: a review.

Detritus particles derived from the decomposition of vascular plants appear to have a high sorptive capability for a wide range of pollutants. Evidence is presented and reviewed which shows detrital concentration of heavy metals, radionuclides, and organochlorine insecticides. A study of a roadside marsh indicates that lead originating from automobile exhausts may reach concentrations as high as 1415 ppm on marshgrass detritus. We suggest that these elevated concentrations may, in turn, be passed on to detritivores which ingest the contaminated particles and experience desorption and assimilation of the pollutant within the digestive tract. Finally, potential mechanisms are listed which might explain detrital sorption; these include; microbial uptake (adsorption and metabolic absorption), association with detrital and microbial lipids, electrostatic adsorption in response to charges on the detritus particles, and formation of complexes and chelates at active sites on the organic molecules of the decomposing detritus.

DDT Residues Absorbed from Organic Detritus by Fiddler Crabs.

DDT and its metabolites accumulate in organic plant detritus estuaries and may persist there for many years. The residues appear to be most abundantly associated with particulates having diameters from 250 to 1000 microns. Detritus particles of this size are ingested by many organisms, sociated DDT residues may enter diverse food chains. Fiddler crabs Uca were fed natural detritus containing DDT residues (10 parts per million) an 11-day experiment and showed grossly modified behavior associated threefold increase in concentration of DDT residues in the muscle of the large claw.