Assessing pesticide concentrations and fluxes in the stream of a small vineyard catchment. Effect of sampling frequency

This study reports on the occurrence and behaviour of six pesticides and one metabolite in a small stream draining a vineyard catchment. Base flow and flood events were monitored in order to assess the variability of pesticide concentrations according to the season and to evaluate the role of sampling frequency on the evaluation of fluxes estimates. Results showed that dissolved pesticide concentrations displayed a strong temporal and spatial variability. A large mobilisation of pesticides was observed during floods, with total dissolved pesticide fluxes per event ranging from 5.7*10-3 g/Ha to 0.34 g/Ha. These results highlight the major role of floods in the transport of pesticides in this small stream which contributed to more than 89% of the total load of diuron during August 2007. The evaluation of pesticide loads using different sampling strategies and method calculation, showed that grab sampling largely underestimated pesticide concentrations and fluxes transiting through the stream

Occurrence of priority pollutants in WWTP effluents and Mediterranean coastal waters of Spain

A comprehensive study aimed at evaluating the occurrence, significance of concentrations and spatial distribution of priority pollutants (PPs) along the Comunidad Valenciana coastal waters (Spain) was carried out in order to fulfil the European Water Framework Directive (WFD). Additionally, PP concentrations were also analysed in the effluent of 28 WWTPs distributed along the studied area. In coastal waters 36 organic pollutants of the 71 analysed, including 26 PPs were detected although many of them with low frequency of occurrence. Only 13 compounds, which belong to four different classes (VOCs, organochlorinated pesticides, phthalates and tributyltin compounds (TBT)) showed a frequency of occurrence above 20% in coastal waters. In the results obtained until now, octylphenol, pentachlorobenzene, DEHP and TBT exceeded the annual average concentration (EQS-AAC), and only TBT surpassed the maximum allowable concentration (EQS-MAC). The most frequent contaminants determined in coastal waters were also present in WWTP effluents. (C) 2011 Elsevier Ltd. All rights reserved.Financial support from Conselleria de Medio Ambiente, Agua, Urbanismo y Vivienda de la Generalitat Valenciana (Application of Water Framework Directive 2000/60/EC on endocrine disruptors and priority substances in coastal areas in the Comunidad Valenciana) is gratefully acknowledged.Martí Ortega, N.; Aguado García, D.; Segovia Martínez, L.; Bouzas Blanco, A.; Seco Torrecillas, A. (2011). Occurrence of priority pollutants in WWTP effluents and Mediterranean coastal waters of Spain. Marine Pollution Bulletin. 62(3):615-625. doi:10.1016/j.marpolbul.2011.01.010S61562562

Removal of Micropollutants from Secondary Effluents and Sludge by Various Processes in Rural and Peri-urban Areas

International audienceThe present work details the results of a comprehensive study dealing with the fate of several families of micropollutants (with various physicochemical properties) through tertiary treatment processes of water and through sludge treatments. Powerful and sensitive analytical techniques were used: 16 metals and 39 organics (pharmaceuticals, polycyclic aromatic hydrocarbons, alkylphenols, pesticides) were analysed in wastewaters; 14 metals and 62 organic hydrophobic micropollutants were measured in sludge (estrogenic hormones, polychlorinated byphenyl, polybrominated diphenyl ethers, polycyclic aromatic hydrocarbons, alkylphenols and other organics). We studied treatment processes adapted for rural areas involving low energy-consumption: trench system, polishing pond, horizontal subsurface flow constructed wetlands with various adsorbing materials (i.e. expanded clay, zeolite, activated carbon, apatite, gravels) running at tertiary stage of water treatment; and sludge drying reed-bed operated at two different resting periods. Our results show that the trench system was not efficient for additional removal of refractory micropollutants. The polishing pond had higher removal efficiencies (between 30 and 70%) for some pharmaceuticals due to indirect photodegradation. The horizontal subsurface flow constructed wetland (HSSF-CW) built with activated carbon showed almost full-removal during more than 330 days for pharmaceuticals, pesticides, several metals and nonylphenoxyacetic acid. For the HSSF-CWs built with expanded clay or zeolite, we obtained removal efficiencies of 70% for half of studied pharmaceuticals and alkylphenols mono- and di-ethoxylates. The removal efficiencies of other substances were much lower than the ones measured with activated carbon, but they were still higher than the ones measured with gravel (filter designed for denitrification) or apatite (designed for phosphorus removal). Due to better oxygen conditions, the sludge drying reed-bed with low frequency of sludge input resulted in better removal for organic micropollutants than the sludge drying reed-bed with high frequency of sludge input

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