The pesticide chlordecone is trapped in the tortuous mesoporosity of allophane clays Thierry Woignier, Florence Clostre, Paula Fernandes, Alain Soler, Luc Rangon, Maria Isabel Sastre-Conde, Magalie Lesueur Jannoyer To cite this version: Thierry Woignier, Florence Clostre, Paula Fernandes, Alain Soler, Luc Rangon, et al.. The pesticide chlordecone is trapped in the tortuous mesoporosity of allophane clays. Environmental Science and Pollution Research, Springer Verlag, 2017, 25 (22), pp.21350-21361. 10.1007/s11356-017-9370-1. hal-01779364 HAL Id: hal-01779364 https://hal-amu.archives-ouvertes.fr/hal-01779364 Submitted on 2 May 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Author's personal copy Environ Sci Pollut Res DOI 10.1007/s11356-017-9370-1 ADVANCES IN ENVIRONMENTAL BIOTECHNOLOGY AND ENGINEERING 2016 The pesticide chlordecone is trapped in the tortuous mesoporosity of allophane clays Thierry Woignier1,2 & Florence Clostre3 & Paula Fernandes3,4 & Alain Soler 5 & Luc Rangon1,2 & Maria Isabel Sastre-Conde6 & Magalie Lesueur Jannoyer3,4 Received: 25 November 2016 /Accepted: 23 May 2017 # Springer-Verlag Berlin Heidelberg 2017 Abstract Some volcanic soils like andosols contain short- and tortuous aggregates of nanoparticles play the role of range order nanoclays (allophane) which build aggregates nanolabyrinths. It is suggested that chlordecone storage in with a tortuous and fractal microstructure. The aim of the work allophanic soils could be the result of the low transport prop- was to study the influence of the microstructure and erties (permeability and diffusion) in the allophane aggregates. mesoporosity of the allophane aggregates on the pesticide The poor accessibility to the pesticide trapped in the mesopore chlordecone retention in soils. Our study shows that the allo- of allophane aggregates could explain the lower pollutant re- phane microstructure favors pollutants accumulation and se- lease in the environment. questration in soils. We put forth the importance of the meso- porous microstructure of the allophane aggregates for pollut- Keywords Chlordecone . Soil contamination . Allophane . ant trapping in andosols. We show that the soil contamination Mesoporosity . Tortuosity . Fractal microstructure increases with the allophane content but also with the mesopore volume, the tortuosity, and the size of the fractal aggregate. Moreover, the pore structure of the allophane ag- Introduction gregates at nanoscale favors the pesticide retention. The fractal Andosols contain clay (allophane) that presents unique struc- tures and physical properties compared to crystalline clays. Responsible editor: Philippe Garrigues Allophane is a short-range order aluminosilicate, the unit cell of which appears as spheroids with a diameter between 3 and * Thierry Woignier [email protected] 5nm(Wada1985) forming aggregates with a fractal structure (Adachi and Karube 1999; Chevallier et al. 2008; Wada 1985; Woignier et al. 2008). The original properties of allophane 1 Institut Méditerranéen de Biodiversité et d’Ecologie marine et have been used in various fields for trapping purpose. continentale (IMBE), Aix Marseille Université, CNRS, IRD, Avignon Université, 13397 Marseille Cedex 20, France Recently allophane has been found to be effective in the sta- bilization of C in soil and composts, offering perspectives for 2 IRD, UMR IMBE, Campus Agro Environnemental Caraibes B. P. 214 Petit Morne, 97235 Le Lamentin, Martinique carbon sequestration technology (Bolan et al. 2012; Calabi- Floody et al. 2011). Synthetic allophane has also been studied 3 Cirad, UPR fonctionnement agroécologique et performances des systèmes de culture horticoles, Campus Agro Environnemental as adsorbents for organic pollutants (Espinoza et al. 2009). Caraïbes B.P. 214 Petit Morne, 97232 Le Lamentin, Martinique Chlordecone (CLD) is an organochlorine pesticide. It is a 4 highly hydrophobic organochlorine pesticide (Kow between Cirad UR HortSys, TA B-103/PS4, Boulevard de la Lironde, −1 34398 Montpellier Cedex5, France 4.9 and 5.4) and poorly soluble (0.35–3mgL )(Soleretal. 5 Cirad UR Banana, plantain and pinneapple cropping system, 2014; U.S. Environmental Protection Agency 2012). It is gen- Campus Agro Environnemental Caraïbes B.P. 214 Petit Morne, erally admitted that chlordecone is poorly biodegradable es- 97232 Le Lamentin, Martinique pecially in environmental conditions explaining its persistence 6 SEMILLA-INAGEA, C/ Babieca, n° 2. Son Ferriol, Palma de in soils (Cabidoche et al. 2009;Epstein1978; UNEP 2007). Mallorca Balearic Island, Spain The CLD poor biodegradability is attributed to its peculiar Author's personal copy Environ Sci Pollut Res chemical structure (bishomocubane Bcage^) and the high ste- shows allophane nano-spheres with a diameter of about 5 nm ric hindrance caused by the ten chlorine atoms. However, (Wada 1985;Calabi-Floodyetal.2011;Chevallieretal. Dolfing et al. (2012) showed that there were no thermodynam- 2008). The allophane spherule aggregates (average diameter ic reasons why chlordecone-respiring or chlordecone- 100 nm) and organo-mineral complexes form small aggre- fermenting organisms should not exist. Previous work studied gates with pores in the mesopore scale (2–50 nm) and with variations in the ratio of CLD-5b-hydro to CLD in soils high organic matter loadings. Seventy-five to 90% of the soil (Clostre et al. 2015a). The mean ratio was lower in andosols organic matter found in the pores is in the 10–1000 nm size than in nitisols. The differences in ratios between andosols and range (McCarthy et al. 2008). nitisols could be due to a lower biodegradation of CLD to The present study hypothesizes that the peculiar properties CLD-5b-hydro, because of a lower availability in andosols. of allophane and specially the porous and tortuous microstruc- Chlordecone biodegradation is not impossible but at least very ture of allophane aggregates favor pollutant accumulation in restricted in these clays. soils and hinder the transfer to the environment. We thus focus This neurotoxic and carcinogenic molecule (Dallaire et al. on the physical properties of the allophane clay to explain the 2012;Epstein1978) still persists in the soil for centuries and pollutant trapping. contaminates foodstuffs and water resources (Coat et al. 2011; For that, we propose to do the following: Fung et al. 2005; Clostre et al. 2015b; Jondreville et al. 2014; Della Rossa et al. 2017) thus leading to human exposure 1) Measure the water chlordecone contamination from through food (Dubuisson et al. 2007; Gimou et al. 2008). andosols having different allophane content. The bioaccumulation process leads to the contamination of 2) Show the influence of allophane concentration on porous the entire food web. Recently, a book provides a presentation features of soils. We measure the porous properties (spe- of various aspects of chlordecone pollution (Lesueur et al. cific surface area, pore volume, fractal features) of several 2016). andosols by small angles X-ray scattering and nitrogen Water is the main vehicle of pesticides transport; so, water adsorption techniques. flow is an important point to consider. However, few studies 3) Finally, we put forth the importance of the clay micro- have focused on pesticide transfers in andosols. When com- structure (fractal range, mesoporous volume, and tortuos- paring cadusafos leaching in andosols and nitisols, it appeared ity) for pollutant trapping. that cumulated water pollution by cadusafos stemming from nitisol percolation was much greater than that from andosols (Cabidoche et al. 2009). In the case of CLD, Cabidoche et al. (2009)collectedsamplesfromlysimetersinstalledonan Experimental andosol and a nitisol. They observed that the concentrations of CLD in similar volumes of drainage water were 3 to 4-fold Soil samples higher in the nitisol than in the andosol. This finding sug- gested that the desorption capacity of nitisol was higher than We sampled 31 soils, andosols (allophane clay) and nitisols that of andosol. (halloysite clay), in Martinique (14°40 N, 61°00 W) in the These results are consistent with results on soil to crops vicinity of the BMontagne Pelée^ volcano. These two kinds contamination found in the literature. Contamination of crops of soils are representative of the main polluted soils found in by soil CLD depended on the type of soil: andosols were less French West Indies (Brunet et al. 2009;Cabidocheetal. contaminating than nitisols (Cabidoche and Lesueur-Jannoyer 2009). The soils we selected were known to be historically 2012; Woignier et al. 2015). Studies on chlordecone transfer polluted by CLD. The soils samples were retained in closed to water and crops led to the general assessment that andosol containers to avoid moisture evaporation and associated struc- tends to retain the pesticide more than other soils. tural changes of allophanes. Samples were stored during So, the literature shows that andosols are generally more 7 days at 4 °C. polluted by CLD than the other kinds of tropical soils (nitisols, The