Trace metal discharge

Generally, variations of trace metal discharge are mainly caused by the changes in suspended matter concentrations. The relative importance of the particulate forms in the decreasing sequence Al > Fe > Mn > Co > Zn > Ni > Cu > Cd has been found by Yeats Bewers (1982) from St. Lawrence River in Canada. According to these authors the lower proportions of the metals in particulate phases from St. Lawrence compared ato the data from the Amazon (Gibbs, 1977) or the Mississippi (Trefry Presley, 1976) rivers are a direct reflection of the contrasting levels of suspended matter in the St. Lawrence (10 mg/1), Amazon (65 mg/1) and Mississippi (580 mg/1). 

Galloway, J. N. (1979). Alteration of trace metal geochemical cycles due to the marine discharge of wastewater. Geochim. Cosmochim. Acta 43, 207-218. 

Mickey, J.W. and Moore, J.N. (1997) The effects of discharge variation on the dissolved concentrations of trace metals and arsenic through Milltown Reservoir, Montana. Abstracts with Programs-Geological Society of America, 29(6), 149. 

Depending on the characteristics of the CMP waste and the environmental discharge permits negotiated with the local authorities, some steps (such as control of suspended solids removal) may not be required, but every CMP waste treatment system requires a method for removing the trace metals. The rest of this chapter will discuss each aspect of the waste treatment system and the pros and cons of combining the unit operations to create a functional treatment system. 

Another possible way to further reduce the cost of ownership of a waste treatment system with this configuration is to forward the concentrated slurry stream to a common filter press if there are various dewatering operations (such as those used for a fluoride waste treatment system or other CMP waste streams) that exist within the facility. Since the liquid in the concentrated slurry does not contain trace metals, this stream can then be reclaimed, recycled, or discharged to sewer rather than re-processed from the start of the system. 

Currentiy, trace metal pollution is not a problem in the Amazon River, with the exception perhaps of localized small-scale occurrences. However, the basin includes several sites of elevated metal releases linked to gold and manganese ore mining and industrial discharges from the large cities. Seyler and Boaventura discuss the likelihood of contamination from these sources. Moreover, they come to the provocative conclusion that elevated fluxes of manganese, copper, vanadium, arsenic, and nickel may already be detectable at the river s mouth due to anthropogenic activities in the basin. Possible metal contamination should be taken seriously in the Amazon, as even small amounts of the more toxic metals may lead to widespread adverse effects in the river s aquatic systems. 

Tovar-Sanchez, A., Sanudo-WiUielmy, S. A., Kustka, A. B., August , S., Dachs, J., Hutchins, D. A., Capone, D. G., and Duarte, C. M. (2006). Impact of dust deposition and river discharges on trace metal composition of Trichodesmium spp. In the tropical and subtropical North Atlantic Ocean. Limnol. Oceanogr. 51, 1755—1761. 

Chiffoleau J.-E., Cossa D., Auger D., and Truquet I. (1994) Trace metal distribution, partition and fluxes in the Seine estuary (France) in low discharge regime. Mar. Chem. 47, 145-158. 

Barshick C. M., Smith D. H., Hackney J. H., Cole B. A. and Wade J. W. (1994) Glow discharge mass spectrometric analysis of trace metals in petroleum, Anal Chcm 66 730-734. 

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