Determination of the background levels of PTEs in arenosols of the Region of Murcia, SE Spain.

Arenosols are soils mostly associated with coastal areas where coastal dynamics favor the accumulation of coarse fractions on the beaches. These sediments of marine origin give rise to coastal soils that support halophilic vegetation and a very special ecosystem. As they are included in urbanized areas and are a priority destination for recreational activities ( swimming, games, relaxation, etc.), they offer a very high level of contact for people. These areas are affected by marine erosion that modifies the coastal profiles, justifying anthropic actions to provide materials with similar granulometries and colors to meet the recreational purposes of the beaches.

The regulations on the quality of the materials that are contributed, regardless of their origin, continental or marine, are very strict in terms of the content of ETPs and other possible pollutants, however, the beaches and their neighboring areas can be affected by tides, spills, or drags that cause an increase in the natural concentration of ETPs. On the other hand, the existence of mining or industrial areas can affect the quality of these soils.

All this justifies a monitoring program in which the first step must be the establishment of the geogenic levels of the sandy soils and the background levels, pointing out the anomalous zones and their environment of influence.

For this purpose, a first sampling has been carried out on the Murcian coast, with a total of 250 samples, establishing the mineralogical groups and the content in ETPs (Pb, Cu, As, Zn, Cd, Hg). The methodology used was the same as that used for the determination of background levels in agricultural soils of the Region of Murcia, except for the sampling design, which was restricted to beach soils. The results confirm the main starting hypotheses and indicate the need to include underwater samples to confirm the implications of contaminant sources.