Evidence map›Paper›PMID 41975198›Full record

ArticleScientific reports2026

Evaluating the restoration of Egypt's Mediterranean Manzala Lagoon: a multi-index assessment of water quality and heavy metals.

Manal A Eissa, Seliem M El Sayed, Fathy A ElSayed, Ahmed Askalany, Mustafa Eissa, Mohamed E Goher

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Article in Scientific reports, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

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3 · Its place in the literature

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0 citing papers in PubMed.

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4 · The record

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5 · Who and what money

Authors and funding

6 authors.

Manal A EissaNational Institute of Oceanography and Fisheries (NIOF), Cairo, 11694, Egypt.
Seliem M El SayedNational Institute of Oceanography and Fisheries (NIOF), Cairo, 11694, Egypt.
Fathy A ElSayedChemistry Department, Faculty of Science, Menoufia University, Shebin El-Kom, Egypt.
Ahmed AskalanyFaculty of Technology and Education, Sohag University, Sohag, Egypt.
Mustafa EissaDivision of Water Resources and Arid Land, Hydrogeochemistry Department, Desert Research Center, Cairo, Egypt.
Mohamed E GoherNational Institute of Oceanography and Fisheries (NIOF), Cairo, 11694, Egypt. smgoher@yahoo.com.ORCID http://orcid.org/0000-0001-9377-2429

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Lake Manzala, the largest coastal lagoon along Egypt’s Mediterranean delta, represents an ecosystem of exceptional ecological and socioeconomic significance, yet it has endured decades of severe environmental degradation. This study presents a comprehensive post‑restoration assessment of its water quality during 2021–2022 to evaluate the effectiveness of ongoing dredging and wastewater‑treatment initiatives. Twelve monitoring stations were systematically surveyed seasonally across the lake’s four sectors, and a wide array of physicochemical variables, nutrient salts, and heavy‑metal concentrations were determined. Integrated indices, including the Canadian Water Quality Index (CWQI), Aquatic Toxicity Index (ATI), Trophic State Index (TSI), Pollution Index (PI), and Heavy-Metal Pollution Index (HPI), were applied, alongside multivariate statistical analysis (Principal Component Analysis, PCA) to interpret spatial patterns and dominant controlling factors. Results revealed a persistent north–south gradient of deterioration, with the southern and southeastern sites receiving heavy loads of organic and inorganic pollutants from the Bahr El‑Baqar, Hadous, and Serw drains. The lake remains markedly hypereutrophic; mean BOD5 and COD values exceeded international thresholds, and high concentrations of Pb, Cd, Ni, and Cr indicate serious ecological risk. CWQI values (39–64) classified most areas as poor to marginal, while HPI values (> 180) indicate heavy‑metal pollution stress. PCA distinguished two principal drivers: (1) anthropogenic organic and metal loading, explaining about 52% of the total variance, and (2) natural oxygenation and self‑purification processes with a minor influence. Despite improved circulation from dredging and the commissioning of the Bahr El-Baqar wastewater treatment plant, overall chemical restoration remains incomplete. Long-term recovery requires catchment-wide nutrient control, sediment remediation, and continuous monitoring to restore the ecological balance and sustain the environmental and economic value of this vital wetland.

Indexed as

EutrophicationManzala lakeMetal pollution indicesPrincipal component analysisWater qualityWater quality assessment

Identifiers

PMID41975198
PMCPMC13076995

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Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.