Continouos Heavy Metal Monitoring System for Application in River and Seawater

Abstract

An automated voltammetric system using solid electrodes was investigated for continuous and on-line remote monitoring of heavy metals in natural waters. Both a polluted river impacted by a copper mine, and costal seawater were monitored automatically every 30 minutes for six months. The huge difference in these two locations demonstrates the wide application range for this system. Results have been automatically monitored every thirty minutes for six months, and can be correlated against a range of parameters, e.g., season, flow of water, temperature, pH etc. The concentration ranges analyzed have been down in the range from 0.2 mg/L in seawater and up to 3 mg/L in polluted river water. Measurements have been performed every 30 minutes in the monitored real samples, with only minor maintenance of the system. Manual sampling with measurements by ICP-MS has been performed frequently for comparison and quality insurance, and the results show good agreement (r 2 avg ¼ 0.98).

Automatic Voltammetric System for Continuous Trace Metal Monitoring in Various Environmental Samples

“…The same trend in variation of the iron concentration over time was found for ICP-MS and voltammetric measurements, and approximately 25% of the total iron content was found to be in an electrolabile fraction. This is close to former findings in river water of similar quality [28].…”

“…Measurements of zinc given in Figure 4 also indicate a speciation trend for zinc which is in good agreement with former findings in river water of similar quality [28]. Each week a manual sample was collected, filtered by 0.45 mm filter, acidified with HNO 3 , and analyzed by ICP-MS.…”

“…Normally, and also as observed here, there is a significant difference between the total amount of iron and the electrolabile amount of iron in somewhat polluted river water of the given quality due to a significant amount of suspended matter, strong complexes and adsorption on charged particles [28]. The stripping peak for iron appears around À 650 mV and origins from the reoxidation of iron deposited on the solid amalgam electrode surface; Fe 0 !…”

Semicontinuous Monitoring of Cadmium and Lead with a Screen‐Printed Sensor Modified by a Membrane

“…Since 1970, a number of flow-cell designs have been developed mainly using hanging mercury drop electrodes [1 -3] or mercuryfilm electrodes [4 -7]. Although stripping sensors led to analyze a variety of matrices, most of them were coupled with continuous automatic systems including filtration [8], dilution [9], extraction [5,10], UV-digestion units [3,11], addition of reagents [3,6,12] and therefore did not allow speciation analyses.…”

Determination of Labile Iron at Low nmol L−1 Levels in Estuarine and Coastal Waters by Anodic Stripping Voltammetry

“…The procedure was tested by analyses of filtered (0.45 mm) samples from the Mersey estuary (Liverpool) in the laboratory. The method was fieldtested by fitting the alloy electrode in an automated voltammetric analysis system [20] which was situated at the Trondheim fjord (Norway). In this case coastal seawater was transferred to the cell using a titanium pump (Tsurumi Pump, Marinemate Submersible Pump Model 50TM2.…”