The APEX software predicts the photochemical transformation kinetics of xenobiotics in surface waters as a function of: photoreactivity parameters (direct photolysis quantum yield and second-order reaction rate constants with transient species, namely (OH)-O-center dot, CO3-center dot, O-1(2) and the triplet states of chromophoric dissolved organic matter, (CDOM)-C-3*), water chemistry (nitrate, nitrite, bicarbonate, carbonate, bromide and dissolved organic carbon, DOC), and water depth (more specifically, the optical path length of sunlight in water). It applies to well-mixed surface water layers, including the epilimnion of stratified lakes, and the output data are average values over the considered water column. Based on intermediate formation yields from the parent compound via the different photochemical pathways, the software can also predict intermediate formation kinetics and overall yield. APEX is based on a photochemical model that has been validated against available field data of pollutant phototransformation, with good agreement between model predictions and field results. The APEX software makes allowance for different levels of knowledge of a photochemical system. For instance, the absorption spectrum of surface water can be used if known, or otherwise it can be modelled from the values of DOC. Also the direct photolysis quantum yield can be entered as a detailed wavelength trend, as a single value (constant or average), or it can be defined as a variable if unknown. APEX is based on the free software Octave. Additional applications are provided within APEX to assess the sigma-level uncertainty of the results and the seasonal trend of photochemical processes.

APEX (Aqueous Photochemistry of Environmentally-occurring Xenobiotics): A Free Software Tool to Predict the Kinetics of Photochemical Processes in Surface Waters.

VIONE, Davide Vittorio
2014

Abstract

The APEX software predicts the photochemical transformation kinetics of xenobiotics in surface waters as a function of: photoreactivity parameters (direct photolysis quantum yield and second-order reaction rate constants with transient species, namely (OH)-O-center dot, CO3-center dot, O-1(2) and the triplet states of chromophoric dissolved organic matter, (CDOM)-C-3*), water chemistry (nitrate, nitrite, bicarbonate, carbonate, bromide and dissolved organic carbon, DOC), and water depth (more specifically, the optical path length of sunlight in water). It applies to well-mixed surface water layers, including the epilimnion of stratified lakes, and the output data are average values over the considered water column. Based on intermediate formation yields from the parent compound via the different photochemical pathways, the software can also predict intermediate formation kinetics and overall yield. APEX is based on a photochemical model that has been validated against available field data of pollutant phototransformation, with good agreement between model predictions and field results. The APEX software makes allowance for different levels of knowledge of a photochemical system. For instance, the absorption spectrum of surface water can be used if known, or otherwise it can be modelled from the values of DOC. Also the direct photolysis quantum yield can be entered as a detailed wavelength trend, as a single value (constant or average), or it can be defined as a variable if unknown. APEX is based on the free software Octave. Additional applications are provided within APEX to assess the sigma-level uncertainty of the results and the seasonal trend of photochemical processes.
16
732
740
DISSOLVED ORGANIC-MATTER; NATURAL-WATERS; HYDROXYL RADICALS; AQUATIC ENVIRONMENT; LABORATORY MEASURES; MODEL PREDICTIONS; AROMATIC KETONES; HUMIC SUBSTANCES; RATE CONSTANTS; TRANSFORMATION
M. Bodrato; D. Vione.
File in questo prodotto:
File Dimensione Formato  
ESPI_2014_APEX.pdf

Accesso aperto con embargo fino al 01/01/2016

Tipo di file: POSTPRINT (VERSIONE FINALE DELL’AUTORE)
Dimensione 672.88 kB
Formato Adobe PDF
672.88 kB 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/2318/155200
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 95
  • ???jsp.display-item.citation.isi??? 94
social impact