The use of biological indicator organisms to monitor trace metal pollution in marine and estuarine environments—a review

Heavy metals such as copper, zinc and lead are normal constituents of marine and estuarine environments. When additional quantities are introduced from industrial wastes or sewage they enter the biogeochemical cycle and, as a result of being potentially toxic, may interfere with the ecology of a particular environment. In different marine organisms, the behaviour of heavy metals is described in terms of their absorption, storage, excretion and regulation when different concentrations are available in the environment. At higher concentrations, the detrimental effects of heavy metals become apparent and their different toxic effects and factors affecting them are also described.

The Effects of Heavy Metals (other than Mercury) on Marine and Estuarine Organisms

A series of chemical extraction procedures are used to obtain data on the partitioning of trace metals among the various geochemical phases of sediments. These components include intersititial water, solubility of solid minerals, ions on exchange sites, metal carbonates, easily reducible phases, organics and sulfides, iron oxides, and lithogenous (mineral residual) fractions. In general, a mass balance of less than 10% deviation can be obtained. Experimental results show very small fractions of trace metals to be in the form of interstital water or soluble ions. Trace metals in the exchangeable phase are almost negligible, and those in the mineral residual phases range from 2.5% Cd for one sediment to 98% Cu for another. The non-residual trace metals content is found to increase with decreasing sand content.

Partitioning of trace metals in selective chemical fractions of nearshore sediments.

Hard- and softwater acclimated adult rainbow trout were statically exposed to copper (12.5, 25, 50, 100, and 200 ppb) for two, 12 h periods at neutral and pH 5.0. Unidirectional Na+, and Cl−, and net Na+, Cl−, K+, and ammonia fluxes were monitored as a measure of branchial ionoregulatory disturbance. Copper concentrations as low as 12.5 ppb led to measurable ion losses. Net Na+, Cl−, and K+ losses were concentration dependent and unaffected by prior acclimation to either hard- or softwater at both neutral pH and pH 5. From 12.5 to 50 ppb net NaCl losses arose primarily as a result of the inhibition ofJ
 in, and at higher concentrations,J
 out was also stimulated. In softwater,J
 in was more resistant to inhibition than in hardwater. However, in hardwater,J
 out recovered to normal levels during the second 12 h period, but no such recovery was found in softwater. Plasma NaCl was inversely correlated with [copper], while plasma glucose and ammonia increased with [copper]. At pH 5.0 and [copper] from 12.5 to 50 ppb, H+ contributed significantly to the total ion loss, while at 100 and 200 ppb, ion losses were no greater at pH 5.0 than at neutral pH. In no case were the effects of copper and H+ strictly additive.

Robert R. Brooks

Papers

APDC-MIBK extraction system for the determination of trace elements in saline waters by atomic-absorption spectrophotometry.