Resumen de Dynamics of chemical microcontaminants in peri-urban agriculture and evaluation of their potential impact on crops and human health
Peri-urban agriculture carries out environmental, social and economic functions and services to the nearby urban areas. Nonetheless, most of these fields are impacted with organic and inorganic contaminants caused by industrialization, sewage and sludge application, vehicular emissions and the reuse of reclaimed water. Therefore, vegetables are exposed to a large number of contaminants present in irrigation water, air and soil. In the recent years, concerns have been raised regarding the presence of chemical contaminants in agriculture crops due to the evidence that plants are able to incorporate, translocate and accumulate them in their edible parts. Despite detected concentrations in food crops are generally low, little is known about the effects of these contaminants on human health. For this reason, field studies are necessary to properly evaluate their incorporation and create databases to assess the human health risk. Currently, there are only few field studies done at real scale, none of them in Spain, which demonstrate the uptake of micropollutants in vegetables irrigated with reclaimed water. In this Thesis, the plant uptake in real field-scale conditions of some trace elements (TEs) and organic microcontaminants (OMCs) chosen by their occurrence in the environment and their physicochemical properties, has been assessed. For this purpose, 4 farm plots located in the peri-urban area of Barcelona (NE Spain) and a rural farm plot far away from the peri-urban area were selected, including different irrigation water qualities and exposure to urban pollution. Lettuce, tomatoes, cauliflowers and broad beans were selected regarding their importance in the horticultural production in the sampling area. The PhD dissertation is split in six chapters. Chapter I gives an overview of the Thesis topic, whereas chapter II explains motivations and aims of the PhD project. The Chapter II assesses the occurrence of TEs and OMCs in irrigation waters. Irrigation waters from peri-urban areas showed higher abundance of selected chemical contaminants than that water from the rural site. Nevertheless, any of the irrigation waters affected seed germination, root elongation or crop productivity. Chapter III assesses the co-occurrence of these contaminants in soil and lettuce leaves, their bioaccumulation factors and how they affect leaf constituents. The higher abundance of these contaminants in the irrigation waters an soils from the peri-urban area had no impact on leaf constituents (chlorophyll, carbohydrate and lipid content). Chapter IV shows the occurrence of the chemical contaminants in different food crops (lettuce, tomato, cauliflower and broad beans) and estimates the human health risk associated with their consumption. Results show that human health risk associated was low and similar between crops grow in peri-urban and rural areas. Chapter V is devoted to the general discussion of three previous chapters, whereas Chapter VI reveals the main conclusions of the Thesis.
