This work shows the potential of using photochemical modelling to assess the river-water ability to photodegrade agrochemicals on a geographic and temporal scale. The case of flowing water requires different data treatment compared to more stationary water bodies (e.g., lakes), but it could allow for the identification of particularly vulnerable environments. Five pesticides were considered here, and the photodegradation rate followed the order bentazon > isoproturon > dimethomorph ∼ chlortoluron > atrazine. The modelled photodegradation kinetics was particularly fast in the river Po, which receives significant input of agricultural nitrate from groundwater and features higher steady-state [•OH] than most other rivers in the region. The fact that the Po eventually collects all river waters in Piedmont is positive, from the point of view of comprehensive photodegradation of pesticides. However, this paradoxical situation of agricultural pollution (nitrate) helping fight pollution from the same source (pesticides) has two important limitations: (i) when compared to the parent compounds, some intermediates deriving from •OH reactions are either more harmful (N-formyl derivatives of phenylureas), or about as harmful (desethyl atrazine); (ii) banned atrazine is no longer sprayed over fields during the plant growth season, but it reaches surface waters from legacy groundwater inputs. The latter are operational also during winter, when photochemistry is least active. Therefore, photochemistry might not ensure considerable attenuation of atrazine during wintertime. Overall, bentazon would be the safest among the studied pesticides because of fast degradation by direct photolysis, and of low ecotoxicological impact of its phototransformation intermediates.

Geographical and temporal assessment of the photochemical decontamination potential of river waters from agrochemicals: A first application to the Piedmont region (NW Italy)

Carena L.
First
;
Comis S.;Vione D.
Last
2021-01-01

Abstract

This work shows the potential of using photochemical modelling to assess the river-water ability to photodegrade agrochemicals on a geographic and temporal scale. The case of flowing water requires different data treatment compared to more stationary water bodies (e.g., lakes), but it could allow for the identification of particularly vulnerable environments. Five pesticides were considered here, and the photodegradation rate followed the order bentazon > isoproturon > dimethomorph ∼ chlortoluron > atrazine. The modelled photodegradation kinetics was particularly fast in the river Po, which receives significant input of agricultural nitrate from groundwater and features higher steady-state [•OH] than most other rivers in the region. The fact that the Po eventually collects all river waters in Piedmont is positive, from the point of view of comprehensive photodegradation of pesticides. However, this paradoxical situation of agricultural pollution (nitrate) helping fight pollution from the same source (pesticides) has two important limitations: (i) when compared to the parent compounds, some intermediates deriving from •OH reactions are either more harmful (N-formyl derivatives of phenylureas), or about as harmful (desethyl atrazine); (ii) banned atrazine is no longer sprayed over fields during the plant growth season, but it reaches surface waters from legacy groundwater inputs. The latter are operational also during winter, when photochemistry is least active. Therefore, photochemistry might not ensure considerable attenuation of atrazine during wintertime. Overall, bentazon would be the safest among the studied pesticides because of fast degradation by direct photolysis, and of low ecotoxicological impact of its phototransformation intermediates.
2021
263
127921
127921
Atrazine; Bentazon; Direct photolysis; Hydroxyl radicals; Nitrate contamination; Phenylureas; Agrochemicals; Atrazine; Benzothiadiazines; Decontamination; Fresh Water; Italy; Kinetics; Nitrates; Pesticides; Photochemistry; Photolysis; Rivers; Water Pollutants, Chemical; Water Purification; Photochemical Processes
Carena L.; Comis S.; Vione D.
File in questo prodotto:
File Dimensione Formato  
Chemo2021_Piedmont.pdf

Accesso riservato

Descrizione: Articolo principale
Tipo di file: PDF EDITORIALE
Dimensione 2.58 MB
Formato Adobe PDF
2.58 MB Adobe PDF   Visualizza/Apri   Richiedi una copia
Piemonte.pdf

Open Access dal 13/08/2022

Descrizione: Postprint
Tipo di file: POSTPRINT (VERSIONE FINALE DELL’AUTORE)
Dimensione 3.03 MB
Formato Adobe PDF
3.03 MB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/1772472
Citazioni
  • ???jsp.display-item.citation.pmc??? 0
  • Scopus 10
  • ???jsp.display-item.citation.isi??? 8
social impact