Sampling protocols and field activities

Before starting field activities, it is essential to define a sampling procedure designed to minimise human errors. This protocol should also respect international scientific community sampling guidance in order to encourage comparison with environmental research carried out in other urban areas. 

Under ideal conditions, soil samples should be collected from near to the centre of each sampling cell. This aspiration may not always be feasible because of the presence of buildings or other exclusion zones. In such cases, every attempt should be made to carry out the sampling respecting, at least, the cell boundary. Soil samphng adjacent to roads should be avoided since atmospheric agents (wind, rain, etc.) can produce an over-accumulation of contaminants. 

Sampling tools (scoops and samples containers) should be manufactured from appropriate quality plastic materials or stainless steel. Operators should not wear or carry any jewellery or metallic apparel. 

It is important to retrieve geographic coordinates of the sampling point from both a topographic map and a GPS receiver (to compare their precision) and to assign an unequivocal location to each collected sample. Any necessary coordinate transformation and projection should be avoided in the field. 

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