Estimating persistent oil contamination in tropical region using vegetation indices and random forest regression.
Ecotoxicol Environ Saf
; 184: 109654, 2019 Nov 30.
Article
en En
| MEDLINE
| ID: mdl-31522059
The persistence of soil contamination after cessation of oil activities remains a major environmental issue in tropical regions. The assessment of the contamination is particularly difficult on vegetated sites, but promising advances in reflectance spectroscopy have recently emerged for this purpose. This study aimed to exploit vegetation reflectance for estimating low concentrations of Total Petroleum Hydrocarbons (TPH) in soils. A greenhouse experiment was carried out for 42 days on Cenchrus alopecuroides (L.) under realistic tropical conditions. The species was grown on oil-contaminated mud pit soils from industrial sites, with various concentrations of TPH. After 42 days, a significant decrease in plant growth and leaf chlorophyll and carotenoid contents was observed for plants exposed to 5-19â¯gâ¯kg-1 TPH in comparison to the controls (pâ¯<â¯0.05). Conversely, pigment contents were higher for plants exposed to 1â¯gâ¯kg-1 TPH (hormesis phenomenon). These modifications proportionally affected the reflectance of C. alopecuroides at leaf and plant scales, especially in the visible region around 550 and 700â¯nm. 33 vegetation indices were used for linking the biochemical and spectral responses of the species to oil using elastic net regressions. The established models indicated that chlorophylls a and b and ß-carotene were the main pigments involved in the modifications of reflectance (R2â¯>â¯0.7). The same indices also succeeded in estimating the concentrations of TPH using random forest regression, at leaf and plant scales (RMSEâ¯=â¯1.46 and 1.63â¯gâ¯kg-1 and RPDâ¯=â¯5.09 and 4.44, respectively). Four out of the 33 indices contributed the most to the models (>75%). This study opens up encouraging perspectives for monitoring the cessation of oil activities in tropical regions. Further researches will focus on the application of our approach at larger scale, on airborne and satellite imagery.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Suelo
/
Contaminantes del Suelo
/
Petróleo
/
Contaminación por Petróleo
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Poaceae
Tipo de estudio:
Clinical_trials
/
Prognostic_studies
Idioma:
En
Revista:
Ecotoxicol Environ Saf
Año:
2019
Tipo del documento:
Article
Pais de publicación:
Países Bajos