Screening of currently used pesticides in water, sediments and biota of the Guadalquivir River Basin (Spain)
Introduction
Water is the primary pathway of pesticides dissemination from their application areas to other parcels of the environment [1], [2]. As a result, the presence of pesticides − especially those polar and highly soluble− in surface, waste and groundwaters, typically in the lower ng L−1 concentration ranges, have been reported [3], [4], [5], [6], [7]. Some of these pesticides are bioaccumulative and due to their vertebrate and non-vertebrate toxicity can affect non-target organisms [8].
In Europe, there are few studies that determine the occurrence of currently used pesticides in environmental compartments other than water and most of them are erratic samplings performed to demonstrate the reliability of an analytical method but not systematic studies evaluating pesticide occurrence and levels in a River Basin [2], [9], [10], [11]. These studies, without being many, are more prevalent in the United States (US) [12], [13], [14], [15], [16], [17], [18], [19].
The Guadalquivir River, chosen as study case, is among the major freshwater sources of the European Basins and the Spain's second longest river. Its natural environment is one of the most varied in Europe, with half of the continent's plant species and nearly all those of the North African region [20]. Thus, maintain a good quality of these ecosystems is of crucial interest. Because of its favorable climate and fertile soils, a wide range of crops are cultivated along the basin and more important, irrigated with its water. Despite its importance and to our knowledge, only few studies have been carried out in this River Basin. These reported the concentrations of persistent organochlorine pesticides [21], [22] and herbicides used in olive groves [23] in waters, the punctual determination of 32 pesticides in water and soil samples [9] and the dissipation of chloridazon and lenacid in a clayey soil of their marshes [24].
The objective of this work is to monitor 50 currently used pesticides in two consecutive years (2010 and 2011) in water, sediment and biota (only 2010) of the Guadalquivir River Basin. The selection of the target pesticides and metabolites was based on extend of use, water solubility and amenability to LC–MS analysis. The list included selected compounds from different families, such as organophosphorus, ureas, phenylureas, azoles, neonicotinoids, carbamates, triazines, chloroacetanilides and acetanilides. This is the first extensive pilot study undertaken in this Spanish River Basin and it intends to improve the knowledge of these pesticides occurrence in the aquatic environment. The concentrations of currently-used pesticides associated with sediments and biota can also ascertain which pesticides are more likely to partition to the suspended sediment phase, or to bioaccumulate in the aquatic trophic chain, and this information will be useful for other watersheds where these compounds are applied.
Section snippets
Site description and sampling
The whole course of the Guadalquivir River was studied, from its source in the mountains of the Jaén province, to its mouth into the Atlantic Ocean at Sanlúcar de Barrameda, on the Gulf of Cádiz. The main river and several tributaries (Borosa, Guadiana menor, Cacín, Genil, Gudaira and Guadiamar) were sampled. The river length is 657 km and its drainage area 57,527 km2. It flows southwest through the region of Andalusia, affecting a population of more than 7 million inhabitants, and passing Córdoba
Results and discussion
Pesticide residues were detected in water and sediments but not in fish. The results obtained during the two sampling campaigns are summarized in Table 1, Table 2 for those compounds detected in more than 10% of the samples. The minimum, maximum and mean values together with the frequency of detection are presented. The absence of pesticides in fish could be related to the polarity of the studied pesticides and metabolites. Most of them are highly polar and consequently little bioaccumulative.
Conclusions
Water quality of the Guadalquivir River Basin has been established by a monitoring study of pesticides carried out for 2010 and 2011. The results reveal that pesticides are widespread in surface waters and sediments. The main influences to the river probably come from agriculture and industrial wastewaters and run-off. WWTPs located in zones with higher urban influence mean an important source of pesticides to the environment.
The river and its tributaries appear as a high-risk scenario for
Acknowledgements
This work has been supported by the Spanish Ministry of Economy and Competitiveness through the projects Consolider-Ingenio 2010 CSD2009, and CGL2011-29703-C02-02. We would also like to thank the persons of the ICMAN research group for taking the samples. P. Vazquez Roig is holder of FPI grant from the Ministry of Science and Innovation (MICINN, Spain).
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