Assessing the source and fate of pesticides in the environment is vital for improving water management policies and remediation actions. Although compound specific isotope analysis (CSIA) has proved to be a valuable complementary tool to track and quantify pollutant degradation and to identify contamination sources, its application to pesticides is still emerging. There are some analytical challenges that restrict the possibilities to exploit the full potential of CSIA in pesticides for environmental applications. To give a sound base on CSIA application in real-case studies, it is also crucial to understand the pesticide transformation processes and their associate isotope fractionations.
In this context, the main objective of ISOTOPEST is to tackle analytical and mechanistic issues that currently limit the application of CSIA for assessing the environmental fate of pesticides, and to provide tools for push forward the frontiers for the implementation of CSIA for environmental studies by industry and regulators. The following challenges are addressed in this project:
-Measurement of isotope ratios for low concentrations of organic compounds in environmental matrices remains one of the major challenges. Isotope-effect-free methods are required for allowing isotope analysis at low concentrations. WP1 of this project aims to overcome these barriers by optimizing extraction and analytical methods for measuring isotope ratios in two pesticides of high environmental concern: the triazine herbicide atrazine and the organochlorine insecticide methoxychlor.
-The database of isotope fractionations associated to different transformation reactions for each pesticide is extremely incomplete. Understanding the transformation processes and their associate isotope fractionations is crucial to give a sound base on CSIA application in real case studies. WP2 of this project aims to increase this database by performing laboratory experiments for knowledge advancement on pathways, mechanisms, and isotope effects of degradation of atrazine and methoxychlor.
-To take the next step and bring CSIA of pesticides to the field, the WP3 of this project is focused on application of CSIA in two contaminated sites for assessing the fate of the target pesticides: a hypersaline lake-aquifer system affected by agricultural activities and contaminated with atrazine, and a fractured aquifer contaminated with methoxychlor as a result of the activities of a former chemical plant. This will provide a further demonstration of the options of CSIA in the evaluation of strategies for natural or induced attenuation, and to trace the sources, sinks and fate of pesticides in the environment.
With these aims, preconcentration and analytical methods for the target pesticides were developed and fully validated. The use of these techniques makes the results and outcomes of the ISOTOPEST project very original and innovative. Furthermore, the project increased the database of isotope fractionations associated to different pesticide transformation processes, which could be relevant under natural conditions or for future remediation approaches. Finally, ISOTOPEST brought demonstration of CSIA in field studies. Multiple lines of evidence, including CSIA, were used for assessing natural attenuation of the target pesticides in the two study sites. These outcomes will give a sound base on CSIA application in real case studies. ISOTOPEST will thus contribute to the competitiveness of Europe in environmental monitoring, risk assessment and contamination mitigating concepts of pesticides.
