Trace Metal Contamination Characteristics and Health Risks Assessment ofCommelina africanaL. and Psammitic Sandflats in the Niger Delta, Nigeria

Abstract

The purpose of this study was to investigate and quantify trace metal concentrations in Commelina africana L. and psammitic sandflats from an intertidal coastal ecosystem in Niger Delta, Nigeria, and to evaluate their spatial distribution, degree of contamination, and source apportionment. The environmental risks associated with soil contamination were elaborately assessed using potential ecological risk index, sediment quality guidelines, and enrichment relative to background levels. The mean concentrations of Cd, Cr, Ni, Pb, and Zn in sandflat soil samples are 0.76 ± 9.0 × 10 −2 , 7.39 ± 8.7 × 10 −1 , 2.28 ± 0.35, 0.024 ± 4.0 × 10 −3 , and 74.51 ± 2.55 mg/kg, respectively. Metal levels indicate strong variability with sampling sites. The order of trace metal concentrations in the Commelina africana L. samples is Zn > Ni > Cr > Pb > Cd. The concentrations varied with the sample locations; and the levels of Pb (0.05 to 0.08 mg/kg) at all locations are found to be significantly below permissible level of 0.3 mg/kg. Potential sources of metal loadings may be associated with localised or diffused anthropogenic activities. The average carcinogenic risks are below 1.0 × 10 −6 threshold values, and the sandflat soils are not considered to pose significant health effects to children and adult males and females. However, the carcinogenicity and noncarcinogenicity risks ranking decrease following the order children > adult males > adult females. Comparatively, the hazard quotient and hazard index indicate that the psammitic sandflats might pose a health risk to children in future.

Risk and Toxicity Assessments of Heavy Metals in Tympanotonus fuscatus and Sediments from Iko River, Akwa Ibom State, Nigeria

“…The following pollution indices were adopted to estimate heavy metal pollution of sediment samples obtained from the study area: (i) degree of contamination (CD) (ii) contamination factor (CF) (iii) pollution index (PI) (iv) geoaccumulation index (I geo ) Contamination degree is estimated to give a holistic impact of multimetals on the environment [12,13]. In this study CD was calculated using the formula developed by Hakanson [14], which states that CD is the sum total of CF of the individual metals CD = ∑ CF Where n corresponds to the number of metals and CF n is the contamination factor of metal n. PLI is categorized as follows: background concentration (PLI = 0), unpolluted (0 < PLI ≤ 1), unpolluted to moderately polluted (1 < PLI ≤ 2), moderately polluted (2 < PLI ≤ 3), moderately to highly polluted (3 < PLI ≤ 4), highly polluted (4 < PLI ≤ 5) and very highly polluted (PLI > 5).…”

Ecological Risk Assessment of Crude Oil Impacted Farmland Soils: A Case Study of Ohaji/Egbema in Niger Delta, Nigeria

“…However, the Igeo of Cd ranged from 31.13 -41.52 which is an indication of extreme contamination. The results of geoaccumulation index in previous studies carried out within Niger Delta byNsikak et al (2016),Aigberua et al (2017),Okoye et al (2021),Aigberua (2021), and Tubotu and Agbaire (2022) indicate that Ni, Pb, Cr and As had values <1. This implies that the sites studied were uncontaminated by these heavy metals.…”

“…This implies that the sites studied were uncontaminated by these heavy metals. However,Aniekan et al (2014),Nsikak et al (2016),Nwankwoala andEmemu (2018), and Tubotu and Agbaire (2022) found in their separate studies that Cd had Igeo values ranging between 1.69 and 5.07. This implies a range of moderate to extreme contamination.…”

Ecological Risk Assessment for Heavy Metals in Agricultural Soils Surrounding Dumps, Huancayo Province, Peru

“…Ecological risk potential index (RI) represents the overall ecological risk of different heavy metals in soil, assesses the likely degree of contamination by trace metals taking into account the relative toxicity of the metals in general and the short and long term response of the environment [Benson et al 2016;Hakanson 1980]. This risk index evaluates the harmful effect of heavy metals in soils, and was calculated through equations 6 and 7:…”

“…(7) (7) Where Ri is the index of the ecological risk potential of an individual metal i, Tri represents the toxicological response factor of metal i, which reflects the level of toxicity and sensitivity of organisms to the metal and CFi is the contamination factor of metal i. The toxicological response factors for As, Cd, Pb, Cu, Cr, Fe and Zn are 10, 30, 5, 5, 2, 1 and 1 respectively [Bhatti et The potential ecological risk factor associated with an individual metal (ERi) was categorized as: low risk (ERi<40), moderate risk (40≤ERi<80), considerable risk (80≤ERi<160), high risk (160≤ERi<320) and very high risk (ERi≥320).…”