Implementation of total fluorescence fingerprinting as a rapid and low cost approach for monitoring pesticide remains in soils and waters in Morocco

The promotion of the agricultural production constitutes a main challenge for Morocco. This goal often results in an increased use of pesticides and fertilizers compromising soils and waters. Moreover, in addition to large stocks of pesticides, the invasion by locusts from southern countries requiring massive use of insecticides remains a potential threat for Morocco. Consequently, a continuous monitoring of the different environmental compartments (soil, water, and air) is increasingly needed for all the Moroccan territory. Owing to hundreds of soil and water samples to control, it is important to develop simple and inexpensive methods to assess pollution levels by pesticides in agricultural soils and neighboring waters. The sophisticated chromatographic methods, in spite of their high accuracy, are very expensive and hardly accessible; they can be reserved for laboratory accurate analyses and statutory inspections. The purpose of this research is to palliate to this issue by developing a spectrometric approach for monitoring soils and waters; an approach which is effective, fast, easy to implement and reliable. In this sense, fluorescence spectroscopy presents a high potential owing to its high sensitivity, ease and rapidity. Total excitation-emission (TEEMs) and total synchronous fluorescence (TSFMs) mappings make it possible to detect remains of fluorescent pesticides in soils or waters. The present investigation aims at the creation/extension of a total excitation-emission and total synchronous fluorescence mapping database to fingerprint those fluorescent pesticides in large use in Morocco. These fluorimetric fingerprints must allow the direct identification of any targeted fluorescent pesticide persisting in soil or water. After a large survey among farmers and agricultural product distributors, to target the best-selling and most used pesticides in different Moroccan regions, one hundred and five (105) pesticides have been fingerprinted. Applicability tests were carried out on the basis of field pre-surveys information and total fluorescence results. In the present work, the maps and synchronous spectra of a set of 57 commercial pesticides are reported. Moreover, four examples of TEEMs/TSFMs fingerprinting applications to recognize pesticideremains in soil samples are shown. The agricultural plantations monitored are located in the great agricultural region Doukkala at the western Atlantic side of Morocco. The catalogue has been enriched by a PCA- based statistical study to constitute groups of pesticides with similar spectrometric fingerprints. The emitting similarity inside pesticide groups, despite different active principles, was explained by similarity of formulation products. The implemented spectrofluorimetric approach is satisfying and seems suitable, at least, as a warning method in case of massive contamination of soils or waters.