Assessment of Heavy Metal Pollution in the Sediments of the River Pra and Its Tributaries

Abstract

An investigative study was conducted to determine the heavy metal pollution in the sediment in the Pra Basin of Ghana from 27 sampling points during the dry and wet seasons using the geo-accumulation index (Igeo), enrichment factor (EF), and pollution load index (PLI). Sediments were acid digested and analyzed for the following selected metals: arsenic (As), lead (Pb), cadmium (Cd), zinc (Zn), manganese (Mn), total chromium (Cr), nickel (Ni), and iron (Fe) using the dual atomizer and hydride generator atomic absorption spectrophotometer (model ASC-7000 No A309654, Shimadzu, Japan). The metal concentrations (mg kg−1) in the sediments were as follows: As (0.175) < Cd (3.206) < Ni (79.927) < Zn (118.323) < Cr (216.708) < Mn (234.742) < Pb (335.381) < Fe (1354.513) in the dry season and As (0.002) < Cd (7.279) < Ni (72.663) < Zn (35.622) < Pb (135.863) < Cr (167.604) < Mn (183.904) < Fe (1138.551) for the wet season. The EF which is an indication of whether metal concentrations are due to anthropogenic activities shows enrichment at all site for the metals Cr, Pb, and Cd in the wet seasons. However, only 4 out of the 27 sites showed Ni enrichment in the wet season. Contrary to the wet season, only Pb and Cr recorded enrichment at all sites during the dry season. Fifteen out of the 27 sites recorded Cd enrichment and 24 out of the 27 sites recorded Ni enriched during the dry season. None of the sites were enriched with Fe, As, Zn, and Mn in either the dry or wet seasons. For both dry and wet seasons, the pollution load index for all the sites except one was at the background levels which is a sign of non-deterioration of the sites studied. In the wet season, the calculated Igeo reveals that the study area is not contaminated with respect to As, Zn, Fe, and Mn; uncontaminated to moderately contaminated with Cd; moderately contaminated with Cr; uncontaminated to moderately to heavily contaminated with Ni; and moderately to heavily contaminated with Pb. The dry season Igeo results reveal non-contamination of the study area with respect to As, Fe, and Mn; uncontaminated to moderately contaminated with Zn; moderately contaminated with Cr; uncontaminated to heavily contaminated with Cd; uncontaminated to extremely contaminated with Ni; and moderately to extremely contaminated with Pb. The high levels of Cd, Pb, and Cr in all the sites are due to unregulated illegal mining activities occurring in and around the study area. It is hoped that this study will prompt the basin management board to improve their management strategies in controlling unregulated illegal mining in the basin sediments.

Geoacumulation of Heavy Metals in Sediment of the Fluvial-Lagoon-Deltaic System of the Palizada River, Campeche, Mexico

“…In sampling sites analyzed in the Palizada river system, the maximum Pb concentrations were presented in the points: LCAR with 10.421 ± 0.218, followed by LDUL2 with 9.190 ± 0.801; LDUL with 9.210 ± 0.656; S7 with 9.153 ± 0.641; S8 9.138 ± 0.542 μg g-1 (Figure 2). Duncan et al [32] The minimum concentrations were in the following sites: S1 (5.515 ± 1.013); S4 (5.793 ± 0.878); S6 (6.010 ± 1.607); LCRU (6.048 ± 0.602). The sampling sites that showed significant statistical differences (p <0.05) were: S1, S7, S9, LCOR, LDUL and LCAR (Table 1), however, there was overlap of means with sites S8, S11, among others.…”

“…The sediments of an aquatic system reflect the environmental quality of an ecosystem, they are fundamental in the dynamics of distribution and accumulation of pollutants, as heavy metals [2]. These elements are released to the environment and have contact with aquatic systems through a process of wet or dry deposition, erosion and/or by direct downloads of anthropogenic activities, which are carried out in collective areas [32]. In the Palizada system, in addition to traditional fishing, there is also industrial activity as it is the extraction of crude oil, which is certainly the main source of economic income in the region [33].…”

“…Variations in metal concentrations per season, occur because during dry season there is an increase in the rate of evaporation and salinity, associated with high temperaturas [13]. While in stormy weather (north winds) the winds help to mix the water column and its nutrients and with this, the resuspension of sediments and also with the washing of the soil surface [13,32].…”

“…The highest levels of Cd may be related to the increase in human and industrial activities in the vicinity of the lagoon in this study, however Pb concentrations were lower than those reported in other investigations. The results of Igeo in the dry season according to Duncan et al [32] showed different contamination levels of the Ghana river, of which the Cd values stood out as unclogged to highly polluted and the Pb was moderately to extremely contaminated, while the Cr values were considered as moderately contaminated. Differences in metal values indicated a variability of heavy metal enrichment sources.…”

Geoacumulation of Heavy Metals in Sediment of the Fluvial–Lagoon–Deltaic System of the Palizada River, Campeche, Mexico

“…The sediments of an aquatic system reflect the environmental quality of an ecosystem; they are fundamental in the dynamics of distribution and accumulation of pollutants such as heavy metals [2]. These elements are released to the environment and have contact with aquatic systems through a process of wet or dry deposition, erosion, and/or by the direct downloads of anthropogenic activities, which are carried out in collective areas [34]. In the Palizada system, in addition to traditional fishing, there is also industrial activity as it is the extraction of crude oil, which is certainly the main source of economic income in the region [35].…”