Biomass-modified carbon paste electrodes for monitoring dissolved metal ions.

Electrodes were prepared by incorporating dried, nonliving biomass of a common lichen, Ramalina stenospora, and Sphagnum (peat) moss in carbon paste. The electrodes were tested on solutions containing Pb(II) and Cu(II) ions by immersing the electrode in the solution for selected periods of time to accumulate ions. Following this the electrode was connected to a potentiostat and the applied voltage scanned from -1.0 to +0.5 V vs. SCE. Any adsorbed metal ions were stripped back into solution at the appropriate oxidizing voltage. The ratio of biomass to mineral oil to graphite has been found to be crucial to electrode performance. Different ratios of the three components using the lichen Ramalina stenospora were evaluated for maximum electrode performance. Only two electrode compositions gave a good electrode response for lead. Electrodes containing peat moss were superior in performance to lichen-containing electrodes for lead. Electrodes based on the lichens Cladina evansii and Letharia vulpina, the marine algae Ulva lactuca and Sargassum fluitans, the blue-green alga Spirulina platensis, and the aquatic plant Eichhornia crassipes did not respond to lead at all. All functioning electrodes studies showed a poor response toward copper(II) ions.

Evaluation of treatment techniques for increasing the uptake of metal ions from solution by nonliving seaweed algal biomass.

The effects of several different treatments on subsequent uptake of several metal ions from solution by six strains of seaweed algae and a sea plant were investigated. Samples of Gracilaria conferta, Eisenia bicyclis, Ulva lactuca, Sargassum fluitans, Cladophora prolitera, Padina pavonica, and Zostera marina were treated with one or more of the following: 1 M HCl, 1 M HNO3, 0.1 M NaOH, 1 M NaOH, acetone, and 60°C water at times from 15 to 60 min and temperatures of 25 and 60°C. Results obtained demonstrate that a treatment time of 15 or 30 min is usually sufficient to produce maximum subsequent metal uptake. Temperature of treatment had little effect.The percentages of Pb, Cu, Zn, Cd, Cr, Mn, Ni, Co, TI, Hg, Au, and Ag subsequently removed from standard metal solutions at a pH of 2-6 by each treated biomass were compared with the percent removal by untreated biomass under the same conditions. All treatments increased the ability of the biomass types studied to bind metals relative to untreated biomass. In addition, pH binding dependence was altered to some extent with a greater degree of binding observed at low pHs by biomass treated with acid. For certain strains of seaweed algae, 0.1 M NaOH treatment produced subsequent uptake of Pb, Cu, Zn, and Cd at levels reaching 100% of initial metal available. Both acidic and basic treatment increased the uptake of Au, Ag, and Hg by four strains of seaweed to nearly 100%.

Variations of heavy metals and arsenic in fish and other organisms from the Calcasieu River and Lake, Louisiana.

The edible parts of several species of fish and other marine organisms inhabiting the Calcasieu River/Lake, Louisiana were analyzed for Cd, Cr, Cu, Pb, Hg, Ag, Zn and As. Concentrations of all metals measured in both intra and interspecies showed no significant variation with sample location. Differences in elemental concentrations were related to organism mobility and not to site-specific variations in metal loadings. Different species of finfish contained only trace amounts of Cd (0.02-0.08), Ag (less than 0.01-0.3), Pb (less than 0.2-0.5), and As (less than 0.1-0.3) mg kg(-1). Concentrations of Cu and Cr were highly variable, in contrast to Zn, which was present in relatively constant amounts across all species (28 +/- mg kg(-1). Sessile organisms such as oysters had the highest concentrations of heavy metals, including Cd. Periphyton and zooplankton were the only groups that showed differences in metal concentrations with sampling location.

Periphyton as monitors for heavy metal pollution in the Calcasieu River estuary.

The levels of copper, lead, chromium, zinc, cadmium, arsenic and silver were determined in periphyton specimens obtained with a diatometer collector. Stations selected were along three important bayous of the Calcasieu River system. Distributions of some metals in the organisms were similar to those found in sediment from the same locations, while other metals appeared to be similar to water concentrations. Concentration ratios of periphyton over sediment greatly exceeded one for the metals chromium, zinc, cadmium, arsenic and silver. The concentrations of heavy metals in the periphyton appeared to yield more information about pollutants than either water or sediment samples collected at the periphyton stations.