Organic Pollutant Penetration through Fruit Polyester Skin: A Modified Three-compartment Diffusion Model

Abstract

The surface of plants is covered by a continuous but heterogeneous cuticular membrane (CM). Serving as the first protective barrier, the uptake and transport behavior of organic pollutants at this interface continue to engage the research efforts of environmental chemist. To date, the contributions of cuticular components as a defense against the organic pollutants penetration remain unresolved. In this study, the unsteady-state penetration characteristics of phenanthrene (PHE) through isolated fruit CM was investigated. PHE penetration was differentiated by three cuticular compartments: epicuticular waxes (EW), cuticle proper (CP) and cuticular layer (CL). The driving force for PHE penetration was ascribed to the sharp concentration gradient built up endogenously by cuticular compartments with different lipophilic affinities. A modified penetration model was established and verified in terms of its general suitability for the hydrophobic chemicals and CMs of various plant species (apple, tomato and potato). The new three-compartment model demonstrates much higher accuracy in characterizing the uptake and transport behavior of semivolatile chemicals with fewer limitations in terms of environmental conditions and complexity (e.g., coexisting contaminants and temperature). This model could contribute to a more comprehensive understanding on the role of polymeric lipids in the organic pollutant sorption and transport into plants.

Dependence of Plant Uptake and Diffusion of Polycyclic Aromatic Hydrocarbons on the Leaf Surface Morphology and Micro-structures of Cuticular Waxes

“…For a deeper understanding of the organic pollutant uptake process and diffusion behavior, the diffusion driving force is introduced. It was widely recognized that the fugacity gradient generated between the plant surface and the inner tissue was the driving force for organic pollutant diffusion1125. As presented in Fig.…”

“…Of the total PAH emission into the urban environment, 40% is scavenged by vegetation via dry and wet deposition67. The dynamic exchange of organic chemicals occurs frequently at the plant surfaces and under the impacts of both complex environmental conditions and biological properties of the plant891011. Plant uptake of organic chemicals is considered of great significance as it impacts the environmental transport and fate of PAHs and threatens crop growth3121314.…”

“…Cuticle is recognized as the very first barrier protecting plants from external impacts, and both the outer structures and inner chemical compositions are critical to this process2728293031. Towards the outermost lipid membrane, the cuticular lipids can be differentiated as extractable lipids (waxes) and un-extractable lipids (polymeric lipids) via sequential separation with organic solvent extraction and depolymerization, and polymeric lipids have been identified as the most effective sink, trapping organic pollutants from entering the inner parts of the plant11162532. However, measurements through batch sorption experiments have inevitably neglected the elaborate structure of plant surfaces, and up to now, the interspecies difference in foliar uptake of organic chemicals still remains unresolved3334.…”

“…Foliar surfaces, specifically cuticular matrices, are assembled with vertical heterogeneity in the chemical compositions and lateral diversity in the epicuticular wax morphologies112527303536. Numerous studies have focused on these kinds of multifunctional surfaces and thus biomimic materials development has been inspired373839.…”

Effects of pyrene exposure on immune response and oxidative stress in the pearl oyster, Pinctada martensii

“…Decreases in THC and cell membrane stability may result from the lipophilic binding of pyrene to membrane lipids, which endangers basic cellular functions by altering fluidity and ionic pumps [12]. Because PAHs can penetrate bivalve membrane systems [45], this type of decrease in cell membrane stability has also been studied in bivalves exposed to phenanthrene and water from North Sea oil-wells [31,32], dispersed oil [6], and low molecular weight PAHs, such as anthracene and phenanthrene [23].…”