No abstract

No abstract

Contamination of aquatic systems with potentially toxic trace elements (PTEs) is a major problem throughout the world. The National Park Tablas de Daimiel (NPTD) is considered to make up one of the two most important wetlands in the Biosphere Reserve called "Wet Spot." Since PTEs are good indicator of the prevailing environmental conditions and possible contamination, soil samples collected from 43 sites were analyzed in order to investigate the levels and its distribution of these elements, in the inundated floodplain area of the NPTD wetland. In addition, some physicochemical parameters such as pH, electrical conductivity and organic matter were measured. The total concentrations of 32 trace elements were determined by X-ray fluorescence. The results show that there was accumulation of lead (Pb), tin (Sn), selenium (Se), antimony (Sb), copper (Cu), vanadium (V), nickel (Ni), zinc (Zn), arsenic (As), strontium (Sr) and zirconium (Zr)-in some cases at high concentrations. The interpolated maps showed that the distributions of some of these elements and in some cases the trend in spatial variability are pronounced and decrease from the inlet to the outlet. The values for some elements are higher than the reference values, which is consistent with contamination (some values are higher by a factor of more than 10 compared to the reference). In the case of iodine (I), the levels at some sample points are significantly more than ten times the reference; Se appears in the range from 1.0 to 9.8 mg/kg, with an average value of 3.1 mg/kg, and these can be considered as seleniferous soils. The concentrations found are consistent with the introduction in the wetland of pollution by human activities, such as agricultural non-point sources, uncontrolled fertilization over many years, treatment with urban wastewater and other possible sources.

Mercury is easily transformed from the elemental state or numerous other mercury compounds to its gaseous form. The gaseous mercury species remain in the atmosphere for sufficient time to be carried long distances. In many cases, some of these differences produce a bias in experimental research, especially for the understanding of the soil-plant-atmosphere system in polluted sites. The main controversy concerns the preferential uptake route in plants and whether the process is reversible or not. The aims of the work described here were to acquire a better knowledge of the transfer routes in the soil-plant-atmosphere system and to ascertain whether plant mercury uptake is reversible. Factors such as the presence of mercury in the atmosphere and irrigation water were evaluated using two common species in Castilla-La Mancha: vines ( Vitis vinifera, L.) and olive trees ( Olea europea, L.). The results provide evidence of three important aspects: plant mercury uptake via roots does occur but it seems minor; plant mercury uptake from the atmosphere involves a continuous exchange at the leaf-atmosphere interface; and plant mercury bioaccumulation seems to be a reversible process. These findings have implications for the use of plants as biomonitors by restricting the exposure times, and in phytoremediation, particularly for polluted soils.

No abstract