Detecting Heavy Metals in Soil using field portable x-ray fluorescence - Esa Nummi

Land contamination has become an increasingly high profile issue on the agenda of environmental and regeneration programmes, especially in Europe and in North America. One significant type of land contamination is pollution by heavy metals. Several incidents have attracted major media attention and as a result many enviromental programs have been initiated to address land contamination problems. Previously, the catastrophic consequences on human health and the environment by land contamination were not considered. Today with greater knowledge, land contamination is not seen as just a few isolated severe incidents, but as a widespread infrastructural problem of varying intensity and significance..

Heavy Elements
Heavy elements are normally considered as those with a density of 4 – 5 g/cm3 and higher. Based on this definition, all elements heavier than titanium (Ti) are heavy elements. However, normally only poisonous heavy elements are considered: arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), vanadinium (V), nickel (Ni), lead (Pb) and zinc (Zn). Some of the metals like Cu and Zn are poisonous only in high concentrations and they exist in normal, non contaminated soil. Most often, the heavy elements originate from previous use of the land by industry, for instance from waste burning plants, coal power plants, shooting tracks, mining, traffic and fertilizers. Heavy elements can cause harm both to human health and to the environment. Humans can be exposed to heavy elements by food plants, water and air, but animals and vegetation can also be adversely affected. In different countries there are determined accepted concentration levels (reference value, target value, guideline value, soil quality criteria…) for heavy elements. Levels are determined based on use of the land. A typical classification is for example: 1) play grounds, 2) residential areas, 3) parks, 4) industry areas. Concentration levels may vary significantly from one country to another.