Presence and distribution of pharmaceuticals and heavy metals in soils of a Mediterranean coastal marshland (L'Albufera de Valencia, SPAIN).

Abstract

This work has been developed in the Natural Park of La Albufera (Valencia, Spain), one of the most important marshland of Europe, included in the RAMSAR agreement, but it suffers impacts derived from the high human and industrial occupation, and of the hydrological contributions from the connected irrigation systems. It which includes a coastal lagoon, marshlands, dunes and pinewoods, surrounded by rice fields in its not urbanized part. In the Natural Park area, 20 sampling zones were selected to determine the degree of pharmaceuticals and heavy metals incidence in soils. Total concentrations of 17 pharmaceuticals, covering the most frequently used classes (anti-inflammatories, antibiotics, etc) and 7 heavy metals (Cd, Co, Cr, Cu, Ni, Pb, and Zn) were evaluated. Their distribution in the surficial and sub-surficial horizons was determined together with their spatial distribution, influence of land uses and the possible sources of contamination. Standard analytical methods were used to measure soil physical and chemical properties. Pharmaceuticals were extracted with water at 70 ºC using pressure liquid extraction (PLE) prior to SPE. All extracts were analyzed by liquid chromatography¿tandem mass spectrometry (LC-MS/MS), using both, positive and negative ionization with an ESI interface.Total content of seven heavy metals (Cd, Co, Cr, Cu, Ni, Pb and Zn) in the soil samples were determined by microwave acid digestion and Atomic Absorption Spectrometry with graphite furnace. Zn, Cr and Cu show the highest concentrations in all land uses and zones. Cr is the metal that present maximum concentration in the studied area (254.93 ppm), being almost the only metal studied that exceeds the limits established by the Spanish an EU legislation. Co and Ni shows a tendency to accumulate below the 30 cm depth, the other metal studied continue with the cumulative trend in surface horizons. All analyzed pharmaceuticals were detected in soils, in at least one sample, at concentrations from MDL to 13.2 ng g-1. Carbamazepine was the substance more frequently detected (9 samples). The highest concentrations correspond to acetaminophen (3.83 µg/kg). This study also shows that inside the Natural Park, the northern zone is the most contaminated one in all cases and soil uses. In this zone, the sampling points closer to the coast are those that present higher concentrations of metals.