Dallas lead study

Figure 4 shows an isomap of the lead pollution in the first smelter area of the Dallas Lead Study. The round symbol in the center represents the smelter. The lines are isopleths of lead in soil in pg/g. Note the cluster of closed isopleths encircling the smelter. The large number of concentric isopleths encircling the smelter shows a steep gradient or rapid change in a short distance between a low (200 ig/g) outside and a high (3,000 pg/g) inside. 

Dalla Betta and Boudart21 studied the pretreatment of Pt(NH3)421 exchanged on zeolite Y. They report that direct reduction in H2 leads to the formation of neutral R(NH3)2H2 hydride in the temperature range of 80-100°C, ultimately resulting in agglomeration and thus large particles. They conclude that decomposition of the complex in 02 should be carried out prior to the reduction. 

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