The role of organic matter and clay content in sediments for bioavailability of pyrene

Abstract

Evaluation of the bioavailable fractions of organic contaminants such as polycyclic aromatic hydrocarbons (PAHs) is extremely important for assessing their risk to the environment. This available fraction, which can be solubilised and/or easily extracted, is believed to be the most accessible for bioaccumulation, biosorption and/or transformation. Sediment organic matter (OM) and clay play an important role in the biodegradation and bioavailability of PAHs. The strong association of PAHs with OM and clay in sediments has a great influence not only on their distribution but also on their long-term environmental impact. This paper investigates correlations between bioavailability and the clay and OM contents in sediments. The results show that OM is a better sorbent for pyrene (chosen as a model PAH) and that increasing the OM content reduces the bioavailable fraction. A mathematical model was used to predict the kinetic desorption, and these results showed that the sediment with the lowest content of OM had an F value of 24%, whereas sediment with 20% OM gave a value of 9%. In the experiments with sediments with different clay contents, no clear dependence between clay and rate constants of the fast desorbing fractions was observed, which can be explained by the numerous possible interactions at the molecular level.

Iron Plaque Prevents Partitioning of Polycyclic Aromatic Hydrocarbons on Rice (Oryza sativa) Root Surface

“…The decreases in the relative absorption at 2917 cm –1 were related to the C–H linkage in the saturated aliphatic hydrocarbon, at 1735 cm –1 related to the carboxylic or carbonyl C=O linkage in acetyl ester groups, and at 1045 cm –1 related to the C–O linkage in carboxylic ester. The changes in spectra of rice root biosorbents with removed lipid components were also consistent with the spectral characteristics of lipids extracted from plant root materials (Spasojević et al 2017).…”

In situ and ex situ bioassays with Cantareus aspersus for environmental risk assessment of metal(loid) and PAH‐contaminated soils

“…Notably, Mo can be strongly accumulated in plants (McGrath et al, 2010) with the help of a specific molybdate transporter (e.g., MOT1 from Arabidopsis thaliana) (Baxter et al, 2008;Tomatsu et al, 2007). For PAHs, no differences between the two approaches with no or low transfers (e.g., AQ of 1.60 for the fluoranthene for the plot C ex situ) were observed, probably due to the influence of the high content of soil organic carbon (Martz et al, 2019;Spasojevic et al, 2018) (Table 1). In addition, the high ex situ RC values of some contaminants can result from a higher activity of the snails under laboratory conditions (constant humidity and temperature) and a higher exposure to the soil (by oral and contact exposure) due to the absence of the humus layer.…”

Estimación del secuestro de hidrocarburos en suelo: efecto del contenido y características de la materia orgánica

“…Aldrich Chemistry) a una concentración de 30 mg•mL -1 en una proporción 100:1:1 utilizando como solvente una mezcla hexano:acetona 1:1 (v/v) (Karal). Esta mezcla de hidrocarburos se eligió debido a que e HXD es el mayor componente en el diesel (Jung et al, 2015), mientras que el PHE y el PYR son comúnmente utilizados como hidrocarburos modelo de tres y cuatro anillos aromáticos (Ding et al, 2020;Spasojević et al, 2018). Además, la proporción de hidrocarburos (alifáticos-HAP) utilizados en la mezcla es similar a la que existe en el combustible diesel premium (Lin et al, 2006).…”

“…A pesar de que el PHE y el PYR se han considerado hidrocarburos modelo de HAP de tres y cuatro anillos aromáticos (Ding et al, 2020;Spasojević et al, 2018), es necesario realizar más estudios para determinar la aplicabilidad de las ecuaciones propuestas para estimar el secuestro de otros HAP estructuralmente diferentes al PHE y PYR (aún con la misma cantidad de anillos aromáticos). Esto se debe a que las interacciones que inciden en el secuestro de HAP, incluyen interacciones moleculares tridimensionales con los componentes del suelo.…”

“…En varios estudios, se ha relacionado el secuestro de hidrocarburos con el contenido de MO (Nam et al, 1998), con el contenido de HS (Sun et al, 2010), con la cantidad y tipo de arcillas (Spasojević et al, 2018) y, recientemente, con la composición química de las HS (Ukalska-Jaruga y Smreczak, 2020). El principal problema es que los resultados no son comparables porque hasta el momento no existen técnicas estandarizadas para cuantificar los hidrocarburos secuestrados y éstos, a pesar de no representar un riesgo inmediato a la biota, sí modifican las propiedades fisicoquímicas de los suelos, afectando su fertilidad e interfiriendo con procesos como los ciclos biogeoquímicos (Adams et al, 2008;Martínez-Prado y Soto-Álvarez, 2017).…”