PREVENTION OF CONTAMINATION AND OTHER ACCURACY RISKS IN VOLTAMMETRIC TRACE-METAL ANALYSIS OF NATURAL-WATERS .2. COLLECTION OF SURFACE-WATER SAMPLES

Methods reliably excluding contamination during sampling of surface waters in the open ocean, in coastal waters and estuaries and in inland waters are described in detail. In the open sea the research vessel is a significant source of contamination by heavy metals. Therefore, it must be left in a boat and water is sampled in sufficient distance from the research vessel taking into account all further contamination risks. Sampling in coastal waters is performed preferably from motorboats or cutters (10-25 m length), the size of which permits sampling in front of the boat by means of a sampling bottle attached to a telescope bar. The choice of sampling points must take into account oceanographic parameters, like tidal currents, and ecological aspects, like harbours or estuaries as regions of highlevel pollution. The risks of contamination by the boat are minimised by travelling upstream during sampling in rivers. © 1979 Springer-Verlag.