Bio-concentration of Polycyclic Aromatic Hydrocarbons in the grey Mangrove (Avicennia marina) along eastern coast of the Red Sea

Abstract

There are numerous sources of chemical pollutants which can impact the mangrove ecosystem through adjacent waters, industrial and sewage discharges and air depositions. Polycyclic aromatic hydrocarbons (PAHs) are semi volatile ubiquitous anthropogenic pollutants detected in all environmental compartments. In the monitoring framework for the mangrove ecosystem along the Red Sea coast of Saudi Arabia, nine mangrove stands were examined for the accumulation of PAHs. Polycyclic aromatic hydrocarbons were measured using Gas Chromatography-Mass Spectrometry (GC-MS). The mean values detected for total PAHs in sediments, roots and leaf were 2.98, 8.57 and 23.43 ng/g respectively. The trend of the total PAHs concentration in all sites showed the descending order: leaf > roots > sediments. Beside the sandy nature of the sediments, the presences of all stands in remote areas fare from the direct anthropogenic effects lead to these relative low values. PAH bio-concentration factors for leaf are two to three magnitudes higher than that in roots, suggesting atmosphere deposition /leaf uptake mechanism in addition to the sediment/root mechanism. The diagnostic ratios revealed that the sources of PAHs are mainly pyrogenic.

Investigating mangrove-human health relationships: A review of recently reported physiological benefits

“…Urban run-off, oil spills, industrial effluents and atmospheric pollutants are sources of toxic hydrocarbons that end up in mangrove ecosystems [ 74 ]. Mangrove response to PAHs has remained a curious interest for researchers due to impacts that include plant cell damage, and therefore growth reduction and mortality, morphological and physiological damage, and photosynthetic interference [ 75 ].…”

Transfer and Degradation of PAHs in the Soil–Plant System: A Review

“…44 Nevertheless, it should be noted that both mechanisms are important, and that may lead to unsystematic correlations between PAHs in sediments/ soils and leaves and roots occasionally. 45 Several studies have shown that in heavily contaminated soils, the predominant mechanism for PAHs uptake and accumulation is through the soil−root system, while in regions with high levels of air pollutants, deposition of gaseous PAHs is the primary contributing pathway. 13,46,47 In addition, the root and foliar systems can show different compositional profiles and contributions to the total amount of PAHs.…”

“…Moreover, there is a considerable knowledge gap when establishing a direct correlation between the rate of PAHs uptake and a specific uptake pathway . Nevertheless, it should be noted that both mechanisms are important, and that may lead to unsystematic correlations between PAHs in sediments/soils and leaves and roots occasionally …”

The identification of the new species Nitratireductor thuwali sp. nov. reveals the untapped diversity of hydrocarbon-degrading culturable bacteria from the arid mangrove sediments of the Red Sea

“…Located on the coasts, mangroves have also to withstand the continuous pressure of the growing anthropogenic activities ( Allard et al, 2020 ; Martin et al, 2020 ; Adyasari et al, 2021 ; Luo et al, 2021 ), including urbanization and aquaculture farming ( Maiti and Chowdhury, 2013 ; Fusi et al, 2016 ; Richards and Friess, 2016 ). These activities impact mangroves with sewage, antibiotics, pesticides, microplastic and other contaminants, such as hydrocarbons released by intense ship traffic and numerous deep-sea vents ( Andreote et al, 2012 ; Maiti and Chowdhury, 2013 ; Richards and Friess, 2016 ; El-Amin Bashir et al, 2017 ; Alzahrani et al, 2018 ; Martin et al, 2019b , 2020 ). Stressful conditions can also be induced by other abiotic factors, such as lack of freshwater input, oligotrophic conditions and high salinity, as in the case of the Red Sea mangroves ( Almahasheer et al, 2016 ; Anton et al, 2020 ; Arshad et al, 2020 ; Qashqari et al, 2020 ; Thomson et al, 2022b ).…”