Mangrove Sediments Show Low Heavy Metal Pollution

A study published in Environmental Monitoring and Assessment reports that mangrove sediments in a coastal region exhibit low levels of heavy metal contamination, with pollution indices indicating an unpolluted status. The research examined the distribution and environmental implications of lead (Pb), copper (Cu), and nickel (Ni) in these sediments. The primary objective was to analyze concentration levels, apply geochemical pollution indices, and perform elemental profiling using scanning electron microscopy–energy-dispersive spectroscopy (SEM–EDS).

The findings suggest that the sediments currently hold low levels of these specific metals within the sampled stations and during the specific sampling period. Sediment materials were collected from three distinct locations within a coastal mangrove region. At each of these stations, surface sediments were obtained to represent the site-specific conditions present at the time of sampling.

The researchers utilized three specific geochemical indices to assess the pollution levels: the geoaccumulation index (Igeo), the contamination factor (Cf), and the pollution load index (PLI). These metrics were applied alongside concentration analysis to provide a multi-faceted view of the environmental status of the sediments. The concentration analysis revealed that the levels of lead, copper, and nickel at all sampled locations were below established sediment quality guideline (SQG) thresholds.

Specifically, the concentrations fell under the Threshold Effect Level (TEL) and Probable Effect Level (PEL), as well as the Effects Range Low (ERL) and Effects Range Median (ERM) criteria. According to these selected SQGs, this indicates a low probability of adverse biological effects. This conclusion is strictly limited to the scope of the metals analyzed and the specific sampling period of the study.

The geochemical pollution indices further supported the observation of low contamination. All Igeo values were negative, which classifies the sediments as class 0, or unpolluted. The Cf values indicated low contamination for copper and nickel, while lead showed moderate contamination at only one of the stations.

Additionally, the PLI values at all stations were below one, confirming that the sediments were generally unpolluted. These indices provide a standardized framework for comparing pollution levels across the different sites and metals studied. To investigate the physical and chemical nature of the sediments, the researchers employed SEM–EDS for elemental mapping and morphological analysis.

The SEM–EDS analysis revealed porous and aggregated sediment morphologies. The elemental distributions of lead and copper were found to be relatively uniform across the samples. The elemental spectra obtained from the SEM–EDS analysis were dominated by silicate and aluminosilicate minerals.

Lead and copper were detected only as trace elements within this matrix. The findings suggest that the sediment matrix may contribute to the retention of lead, copper, and nickel under the conditions investigated. However, the authors explicitly note that this interpretation is limited to the measured total metal concentrations, pollution indices, and SEM–EDS observations from the specific stations.

The study does not directly demonstrate long-term accumulation or an ecosystem-scale sink function. The results indicate that, within the limitations of the study, the sediments are not currently acting as a source of significant heavy metal pollution based on the selected guidelines and indices. In summary, the research demonstrates that the mangrove sediments in the studied region exhibit low levels of heavy metal contamination for lead, copper, and nickel.

While the sediments may retain these metals under the investigated conditions, the study does not claim a long-term sink function.

Subject of Research: Heavy metal distribution and pollution assessment in mangrove sediments using SEM-EDS and geochemical indices

Article Title: Evaluating heavy metal pollution in mangrove sediments via SEM–EDS elemental mapping

Article References: Khotimah, N. N., Rozirwan, R., Fauziyah, F., Putri, W. A. E., Ulqodry, T. Z., & Ermayanti, E. (2026). Evaluating heavy metal pollution in mangrove sediments via SEM–EDS elemental mapping. Environmental Monitoring and Assessment, 198(11), Article 1255. https://doi.org/10.1007/s10661-026-16072-9

Image Credits: AI Generated

DOI: 10.1007/s10661-026-16072-9

Keywords: mangrove sediments, heavy metal pollution, SEM-EDS, geochemical indices, lead, copper, nickel, coastal environment, sediment quality, environmental monitoring, Evaluating, heavy