River Influx Drives Heavy Metal Pollution in Manila Bay, Philippines: An Insight from Multivariate Analyses

Abstract

Recent work on heavy metal pollution in Manila Bay suggests elevated concentration in the surface sediments. It is critical to identify the sources of these heavy metals to effectively rehabilitate the bay. Our study investigated the sources of the heavy metal pollution that ended up in Manila Bay and the risks associated with these toxic metals based on a recent survey conducted. Surface sediment samples with higher heavy metal concentrations were found in the upper to middle parts of the bay while lower concentrations were in the southeast areas. Multivariate analyses such as hierarchical cluster analysis (HCA), principal component analysis (PCA), and Pearson correlation analysis were used to identify the sources of the heavy metals. The heavy metal pollution in Manila Bay is attributed to several rivers draining northeast of Manila Bay, particularly the Marilao-Meycauayan-Obando River System (MMORS) which is cited as one of the 30 dirtiest river systems in the world. The ecological risks associated with heavy metals in the sediments found higher incidences of toxicity in north and middle parts of Manila Bay. Cu and Cr posed the highest risks of toxicities than any other heavy metals. Based on our analysis, the counterclockwise water gyre of the bay can explain the distribution and ecological risks associated with the heavy metals as supported by the findings of the PCA. Given the high priority by the Philippine government to rehabilitate the bay, our study strongly shows that efforts to restore the ecological status of Manila Bay will only succeed if the pollution from major rivers draining to it will be properly addressed.

Understand COVID-19 through Heavy Metals Pollution

“…Theta (P.3) variant, additionally referred to as GR/1092K.V1 contains key spike mutations (141-143 deletion E484K; N501Y; and P681H) and changed into first detected withinside the Philippines and Japan in February 2021 [88]. Study done by Diwa, R et al [89] showed that heavy metal pollution in Manila Bay is due to several rivers flowing northeast of Manila Bay, especially the Marilao Meycauayan Obando River System. It is ranked as one of the 30 dirtiest river systems in the world.…”

Modelling the Origin, Fate, and Ecological and Health Impacts of Heavy Metals from an Abandoned Mercury Mine in a Paradise Island in the Philippines

“…To identify the sources of these heavy metals, we performed multivariate analyses such as HCA, PCA, and Pearson correlation analysis. These are useful tools for finding the causes of heavy metal pollution by grouping them according to similarity in their sources [12][13][14]25,[37][38][39]. HCA grouped the sampling areas into 3 clusters.…”

“…While existing research were conducted to assess the extent of mercury contamination in the surrounding area of the abandoned mine, detailed health and environmental impacts of ad mixture of the heavy metals and their possible origins remain unknown. Therefore, this study employed multivariate analyses, such as hierarchical cluster analysis (HCA) and principal component analysis (PCA), to determine the possible ecological and health risks associated to the heavy metals in soils and sediments [11][12][13][14]. To our knowledge, this is the most detailed study on the long-term health impact and source apportionment of heavy metals in the island paradise billed as "one of the most beautiful islands in the world" [15].…”

“…RI is rated as < 150 low risk; 150 -300 moderate risk; 300 -600 considerable risk; and > 600 very high risk. The ER i of the individual heavy metals are classified as < 40 low risk; 40 -80 moderate risk; 80 -160 considerable risk; 160 -320 high risk; and > 320 very high risk[12,21,25].…”