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The distribution and concentrations of 6 indicator polychlorinated biphenyl (PCB) congeners, nos. 28, 52, 101, 138, 153 and 180, were determined in surface sediments from the North End Lake in Port Elizabeth, South Africa. Forty-two surficial sediment samples were collected from different locations covering the region that receives the majority of the industrial waste, urban effluents and runoff and thus expected to be contaminated with different degrees of contamination. The analysis was achieved by gas chromatography-mass spectrometry (GC/MS) using the internal standard method. The total PCB concentrations in the samples ranged from 1.60 to 3.06 ng·g -1 dry weight (dw). The concentrations of congener profiles showed significant differences. Generally, the highest PCB concentrations were associated with high organic matter contents and small grain size. The highly chlorinated PCBs dominated with regards to the levels in sediments. PCB 138 was the major contributor to the total PCBs and was detected at 100% of sites. This study provided a snapshot of the PCB contamination status in the North End Lake sediments, and allowed for a comparison between the investigated system and other systems worldwide.

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Two configurations of an electric arc were used to generate atomic emission using a Jacob's ladder. The flameless emissions thus achieved were considerably more intense than that of a traditional flame coloration test, making it well-suited for demonstrations for large audiences. The first configuration employed an arc generated by a low current transformer that created a rising arc between two vertical conductors. The conductors were coated with selected salts or compounds in segments such that the rising arc changed color on ascent. The second configuration consisted of a similar Jacob's ladder run at high current, and the arc was contained in a flask which enhanced and prolonged the emission accompanied by a deep reverberating humming sound which added an audio component which ordinary flame coloration experiments lack. The demonstration was well-suited for a variety of audiences, and since it combines the concept of atomic emission with those of transformers, Jacob's ladders, electrical arcs, and plasma, the fourth state of matter, a profound multifaceted learning experience was achieved.