Trace metal

About: Trace metal is a research topic. Over the lifetime, 5125 publications have been published within this topic receiving 181046 citations.

Trace metal distribution coefficients in the Weser Estuary (Germany)

Abstract: Trace metals in the dissolved phase, and in operationally defined available and total particulate associations, have been determined along an axial transect of the Weser Estuary, together with measurements of salinity, temperature, pH, dissolved oxygen, suspended particulate matter (SPM), chlorophyll a, free and attached bacteria, particulate carbon and particle specific surface area. Throughout the estuary the dissolved metals exhibited non-conservative behaviour due to sorption reactions with particle surfaces and sediment-water exchange processes. This reactivity was enhanced at the fresh water-brackish water interface where changes in the master variables were most pronounced. The influence of sorptive processes on total particulate metal distributions was not evident and major compositional variability was ascribed to physical mixing of different particle populations. The relative proportions of trace metals in the dissolved and solid phases were interpreted in terms of conditional distribution coefficients, KDs, whose magnitude depends critically on which fraction of particulate metal is selected (i.e. available or total). The KDs for Fe and Mn increased with increased SPM concentration, whereas those for Cu, Ni, Zn and possibly Pb decreased with SPM; such observations are related to whether particle-water exchange processes at any locality in the system are far from or at (quasi-) equilibrium, and to differences in the sorptive characteristics of suspended particle populations. These results have implications for the behaviour of trace metals in the Weser Estuary and are also discussed in the context of the value of the KD concept for quantitative modelling of dissolved trace metal distribution in estuaries.

Geochemistry of Cu, Co, Ni, Zn, Cd and Cr in the surficial sediments of a tropical estuary, southwest coast of India: a granulometric approach

Abstract: Geochemical characteristics of six trace metals – Cu, Co, Ni, Zn, Cd and Cr – in the bulk sediment and sand, silt and clay fractions of a tropical estuary on the southwest coast of India have been studied and discussed. In bulk sediment, the trace metal concentration is controlled mainly by the textural composition of the sample. Mud, sandy mud and sandy silt register higher concentrations of trace metals than that in sand-dominant sediments. The granulometric partitioning studies also re-affirmed the role of particle size in enriching the trace metals. The silt and clay fractions exhibit 7–8 times the enrichment of Cu and Cd compared to that in sand. The enrichment factors of Zn, Cr, Ni and Co in the silt and clay fractions, compared to that in sand, are 5–6, 4–5, 2–5 and 2–3 times, respectively. The trace metals in the sand fraction, particularly Ni and Cr, exhibit strong positive correlation with the heavy mineral content of the samples. It clearly indicates a heavy mineral pathway to the trace metals in the sand fraction. Cu and Co in silt and clay fractions exhibit a marked decrease towards the high saline zones of the estuary. This is attributed to the desorption of Cu and Co from particulate phases during estuarine mixing. Contrary to Cu and Co, the content of Zn in the clay fraction shows a marginal increase towards the estuarine mouth. This could be explained by the influx of Zn-rich contaminant discharges from Zn-smelting industries located slightly north of the estuarine mouth. The released Zn will effectively be held in the lattices of the clay mineral montmorillonite, which also exhibits a marked increase towards the estuarine mouth. The anomalously high values of Cd in some places of the Central Vembanad estuary is attributed to the local pollution.