1 Pesticides contamination in water and sediment of the aquatic systems of The 1 Natural Park of the Albufera of Valencia (Spain) during the rice cultivation period. 2 Sara Calvo a , Susana Romo a , Juan Soria a , Yolanda Picó b 3 a Water Ecology Group. Departamento deEcología. Edificio Investigación Jerónimo Muñoz. Universitat de 4 València. 46100 Burjassot, Valencia, Spain. 5 b Food and Environmental Safety Research Group. Centro de Investigaciones sobre Desertificación –CIDE 6 (CSIC-UV-GV), Moncada, Spain. 7 Corresponding author: Sara Calvo. E-mail: sacalgar@alumni.uv.es 8 9 Graphical abstract 10 11 12 Abstract 13 The Natural Park of the Albufera (Valencia, Spain) is a Mediterranean wetland where rice cultivation dominates 14 the agricultural activity. The purpose of this study was offer broader information of the current state of the wetland 15 assessing the contamination by pesticides in four aquatic habitats during rice cultivation period in 2016. Liquid 16 chromatography tandem with mass spectrometer (UHPLC-MS/MS) was used to determinethe pesticides in water 17 and sediment samples from the rice fields, Lake Albufera and irrigation and outlet channels. 21 pesticides were 18 detected in our samples (seven already forbidden by European legislation). Higher values than 10000 ng L -1 of 19 accumulated pesticides had been observed in the water samples of the midterm of the cultivation period (July). 20 The sediment samples presented values ten times lower than the water samples. The habitat showed significant 21 differences in the concentrationsof the water and sediment samples (Two-way Permanova, p < 0.05) at the end 22 and in the midterm of the cultivation period, respectively. Bentazone and tricyclazole were the dominant and most 23 ubiquitous pesticides in the habitats. The quantities also calculated in real water volume showed that the rice fields 24 and Lake Albufera supported more than 100 kg of pesticides in July. Finally, negative effects in the phytoplankton 25 and some taxa of the biota of the Natural Park were predicted in the risk assessment (Risk Quotient > 1). The data 26 Pesticide balance in the aquatic systems of The Natural Park of the Albufera in July 2016. Lake Albufera Mediterranean Sea Irrigation channels Outlet channels Ricefields 36 % 2 % 62 % 40 % 1 % 58 % Sediment (%) Fungicides Herbicides Metabolites Insecticides kg kg kg day -1 kg day -1 Water