Assessing soil pollution by beryllium contamination in an olive orchard of southern Italy

Researches on beryllium in soil have, until now, mostly addressed issues on timing of landscape development, hillslope creep, weathering and formation of minerals, dust accumulation and the genesis of loess/paleosol sequences. Actually, beryllium, being one of the world's most toxic metals, which accumulates in soil not only from human activities but also from natural sources, should be approached in contamination key. Because of its toxicological effects, Be may seriously affect the health of human beings and other animals, as well as overexploits the natural soil functions of buffering, filtering and transforming. Therefore monitoring the contamination threshold concentration of beryllium to assess soil conditions and any need for protective action is of interest. A threshold provides a baseline against which sustainability can be assessed. The Italian government has developed criteria for evaluating soil pollution of public land to protect human health, through the Italian Legislative Decree no. 152 of 03/04/2006. The study was aimed to quantify natural concentration and spatial distribution of beryllium (9Be) in the topsoil in an olive orchard of southern Italy (Calabria). Topsoil samples and olive leaves at 100 locations were collected in a 100 m x 100 m olive orchard. Soil samples and olive leaves were ground, dried, weighed, and digested in aqua regia for laboratory analyses with ICP-MS. A geostatistical approach was used to quantify and map the spatial distribution of natural concentration of beryllium (9Be). The soil beryllium concentration varied spatially from a minimum value of 1.50 mg kg-1 to a maximum of 4.51 mg kg-1. In 98% of the soil samples the content of beryllium exceeds the Italian threshold value (2 mg kg-1) for public, private and residential green soil use. Therefore, the study area is a potentially contaminated site where the remediation must be carried out. These regulatory criteria might be useful in making risk assessments. The measured values of beryllium in the study area are also higher than the mean value of beryllium in the Earth's crust (2.6 mg kg-1). Beryllium contents in Olive leaves ranged from 0.0004 mg kg-1 to 0.0478 mg kg-1 and they are too low to affect human health by consumption of olives and olive oil. These results showed that olive plants take up beryllium from soil in small amounts, and also when it occurs in mobile forms, the measured Beryllium contents are not toxic for plants because of the high binding capacity of the soil for Be.