Integrated electrochemical and spectroscopic assessment of heavy metal bioaccumulation in mangrove plants: A sustainable strategy for environmental monitoring and risk mitigation
Shamsa Alotaibi , Abdelaziz Elgamouz , Abdel-Nasser Kawde , Kareem A. Mosa , Saad BenHaiba , Soukaina El Abbadi
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引用次数: 0
Abstract
Mangrove forests play a vital role in coastal protection, biodiversity, and pollution mitigation, but they are increasingly threatened by heavy metal uptake associated with industrialization. However, real-time, in-situ, and non-destructive methods for monitoring metal bioavailability within mangrove plants remain unavailable. This study develops and tests an acupuncture Needle Electrode modified with reduced graphene oxide and bismuth nanoparticles (ANE/rGO/BiNPs) for real-time heavy metal detection in Alhamriyah Mangrove Reserve (AHMR). To establish baseline contamination levels for a range of elements, water and sediment samples were collected from three sites within the reserve and analyzed using inductively coupled plasma optical emission spectrometry (ICP-OES). The chemical oxygen demand (COD) was high (> 11.0 mg/L), and the sludge was quite polluted with Cd, In, Ag, and Bi as the contamination factor (Cf > 10). Analysis of a mature mangrove tree showed highest metal accumulation in roots, with contamination factors: In (870.460) > Ag (636.386) > Cd (416.588) > Bi (248.918) > Tl (93.144), suggesting industrial sources and highlight the need for monitoring non-traditional metals like Cd. Mangrove seedlings were irrigated with varying levels of Cd, Pb, and Zn, showing dose-dependent metal accumulation. Roots primarily accumulated Cd and Pb, indicating phytostabilization potential, while Zn's higher mobility suggests suitability for phytoextraction. The ANE/rGO/BiNPs sensor was inserted into living mangrove tissues to detect metal uptake using Square Wave Voltammetry (SWV). After four weeks, electrochemical readings showed high accumulation levels (Cd: 5182.29 µM, Pb: 5076.25 µM, Zn: 41,998.50 µM) under high treatment. Compared to much lower ICP-OES values (Cd < 150, Zn < 3, Pb < 5), electrochemical contamination factors were significantly higher, demonstrating the sensor’s superior sensitivity and effectiveness for non-destructive, real-time monitoring of bioavailable metal uptake in mangroves. This novel approach highlights the potential of needle-based sensors as practical tools for in-situ biomonitoring and environmental risk assessment in vulnerable coastal ecosystems.