Metal Concentrations in Sediments of the Alinsaog River, Santa Cruz, Zambales, Central Luzon, Philippines.

Rowena R Sazon,Veronica P Migo

doi:10.5696/2156-9614-10.27.200914

Abstract

Background.Efforts are needed to evaluate heavy metal concentrations in aquatic sediments which serve as repositories and as sources of contamination of other habitats.Objectives.The present study assessed temporal changes in the pH, particle size and concentration of metals in sediments of a mining-affected river in Zambales, Philippines.Methods.Sediment samples were collected at different periods in four stations along the river using a modified Van Veen grab. The samples were subjected to quartering, air-drying, and sieved through a mesh of 40 mm prior to X-ray fluorescence spectroscopy analysis using Thermo Scientific Niton XL3t to determine metal concentrations. The sediment particle size was analyzed by the sieve method and soil pH by the electrode method.Results.Measured metal concentrations in the sediment were as follows: iron (Fe)> calcium (Ca)> chromium (Cr)> nickel (Ni)> manganese (Mn) with averages of 174.6 mg/g, 7.89 mg/g, 6.54 mg/g, 4.82 mg/g, and 2.75 mg/g dry matter (DM), respectively. The mean pH of riverine sediments was generally neutral, except for Station 4. In terms of particle size, silt and clay fractions increased in the upstream station but decreased in the midstream and downstream stations across the sampling periods. The flooding brought by Typhoon Koppu resulted in lowered concentrations of Fe, Mn, Cr, and Ni and an upsurge in Ca and potassium levels.Discussion.Most of the heavy metals (Fe, Ni, Cr, Mn) exceeded the probable effect level (PEL) for inorganics in sediments, suggesting that the adverse effects of these metals on the environment and aquatic organisms are expected to occur frequently. In comparison with Station 4, which was less affected by siltation, there was a sign of metal enrichment in the area. This indicates that soil erosion and runoff, which might have been triggered by vegetation loss, mineral extraction, and agricultural activities, had a significant impact on the quality of river sediments.Conclusions.The findings of the study point to the need for the formulation and implementation of appropriate regulatory measures for the protection and rehabilitation of the heavy metal-loaded river.Competing Interests.The authors declare no competing financial interests.

Highlights

Pollution of aquatic environments is a global concern
In comparison with Station 4, which was less affected by siltation, there was a sign of metal enrichment in the area. This indicates that soil erosion and runoff, which might have been triggered by vegetation loss, mineral extraction, and agricultural activities, had a significant impact on the quality of river sediments
Reports show that the study area is geologically rich in Cr and Ni deposits, the findings suggest that mineral extraction and other landbased activities contributed to the enrichment of heavy metals in the area under study.[39, 40]

Summary

Introduction

Pollution of aquatic environments is a global concern. Efforts have been carried out to abate this problem. In comparison with Station 4, which was less affected by siltation, there was a sign of metal enrichment in the area This indicates that soil erosion and runoff, which might have been triggered by vegetation loss, mineral extraction, and agricultural activities, had a significant impact on the quality of river sediments. Heavy metals are non-degradable and toxic to organisms, even at low concentrations They can be transported through the atmosphere or via flowing water and tend to end up in the bottom sediments, soil, and underground water.[4] Once these elements enter the river system, they tend to bind to particulate matter and adsorb to or co-precipitate with carbonates, oxyhydroxides, sulfides, and clay minerals in the sediments.[5] Sediment quality can serve as an important indicator in the monitoring of aquatic pollution

Results

Discussion

Conclusion