Analysis of Heavy Metal Contamination in Urban River Sediments and Its Environmental Impact

Thesis Abstract

Urban river sediments are critical repositories of contaminants, particularly heavy metals, which pose significant risks to aquatic ecosystems, human health, and the broader environment. Escalating industrial activities, urban runoff, and vehicular emissions have exacerbated the accumulation of heavy metals such as lead (Pb), cadmium (Cd), zinc (Zn), and arsenic (As) in sediment matrices within metropolitan areas, necessitating comprehensive assessment and monitoring to inform sustainable urban planning and pollution mitigation strategies. This research aims to quantify the concentration of selected heavy metals in sediments from the River Harmony, evaluate their spatial distribution, and assess potential environmental risks associated with their presence. Specifically, the study seeks to (1) determine the levels of heavy metals in sediment samples collected from ten strategically chosen sites along River Harmony; (2) analyze the spatial variation of heavy metal concentrations using geostatistical tools; (3) evaluate sediment contamination status employing pollution indices such as the Contamination Factor (CF) and Soil Pollution Index (SPI); and (4) investigate the potential ecological risks using sediment quality guidelines and risk assessment models. The methodology employs a cross-sectional research design utilizing both qualitative and quantitative data collection methods. The population comprises sediment samples from different points along River Harmony, selected based on proximity to industrial zones, urban runoff outlets, and residential areas. A total of 100 sediment samples are collected through stratified random sampling to ensure representative coverage of suspected contamination hotspots. Heavy metal concentrations are determined using atomic absorption spectroscopy (AAS), following standard procedures for acid digestion and sample preparation. The validity and reliability of analytical instruments are established through calibration using certified reference materials, with duplicate samples tested to confirm reproducibility. Descriptive statistics summarize the data, while inferential analyses, including Pearson correlation, multiple regression, and ANOVA, are employed to examine relationships between variables and spatial variations. Geostatistical tools such as kriging interpolation models visualize contamination distribution patterns. Expected findings suggest elevated concentrations of heavy metals exceeding permissible limits specified by environmental standards, particularly near industrial discharge points, with significant spatial heterogeneity. The contamination indices are anticipated to classify several sampling sites as highly contaminated, with potential ecological risks indicated by sediment quality guidelines. The study hypothesizes a positive correlation between metal concentrations and proximity to anthropogenic activities, confirming the influence of urban and industrial pollution sources. These findings are expected to underscore the extent of heavy metal pollution in urban river sediments and its implications for environmental health. This research advances knowledge by providing a detailed spatial assessment of heavy metal contamination in urban sediments, integrating contamination indices with geostatistical modeling to delineate pollution hotspots. It contributes to environmental monitoring frameworks by validating the applicability of pollution indices and risk assessment models within urban contexts. The study’s recommendations include targeted remediation efforts at identified hotspot zones, stricter regulation of industrial effluents, and the implementation of sustainable urban runoff management practices. In conclusion, the study emphasizes the urgent need for continued monitoring of heavy metal loads in urban river sediments, advocating for the development of integrated pollution management strategies to mitigate environmental and health risks. It calls for policy interventions for pollution control and promotes community awareness about urban sediment contamination, supporting the broader goal of sustainable urban water resource management. Future research directions include longitudinal studies to track temporal changes in sediment contamination and exploring biological remediation techniques for heavy metal detoxification.