Assessment of Heavy Metals Pollution in Soft Sediment of the Severn Estuary and Inner Bristol Channel System (Published)
For several decades, the Severn Estuary and Bristol Channel have been contaminated by heavy metals despite the many ecosystem services it provides. Therefore, this paper is devoted to the systematic assessment of heavy metals (Cd, Cr, Ni, Zn and Pb) pollution in soft sediments of the Severn Estuary and Inner Bristol Channel. An unpublished 2016 monitoring survey data of the Severn Estuary and Bristol Channel was obtained from the UK Environment Agency to assess seasonal variations, spatial distribution, exceedances, ecological risk, and potential sources of heavy metals. Seasonal variations between the concentration of heavy metals during summer and winter revealed that irrespective of seasons the concentration of heavy metals had the trend Zn > Cr > Pb > Ni > Cd. Concentrations of metals were higher in summer than winter, and there was a significant difference between metals concentration in summer and winter (P < 0.05). Spatial distribution of metals using the Empirical Bayesian Kriging (EBK) model revealed that irrespective of the seasons, concentrations of Cd, Cr, Ni, Zn and Pb in the distinct reaches of the estuary followed the trend Severn middle > Severn lower > Inner Bristol Channel > Severn upper. One-way ANOVA, which was followed by the Tukey’s HSD test, showed a significant difference between the mean concentration of heavy metals in the distinct reaches of the study area at p ≤ 0.05. Assessment of heavy metals using the USEPA Sediment Quality Guideline revealed that none of the reaches of the estuary was polluted with Cd. The Severn upper was not polluted with Pb. The Severn middle was moderately polluted by Ni but heavily polluted with Zn, Cr and Pb. Other reaches of the estuary were moderately polluted with Cr, Ni, Zn and Pb. Assessment of ecological risk of heavy metals using pollution indices such as geo-accumulation index (Igeo), contamination factor (CF), metal pollution index (MPI) and pollution load index (PLI) revealed that heavy metals such as Zn, Pb, Ni and Cr in the distinct reaches of the estuary and might pose an adverse effect on biota and ecosystem services of the Severn Estuary and Inner Bristol Channel. Identification of potential sources of metals using Pearson correlation, hierarchical cluster analysis (HCA) and principal component analysis (PCA) suggested that heavy metals all originated from anthropogenic sources.
Analyses of Some Heavy Metal and Nutrients of Water Samples from Ajegunle Creek in Lagos (Published)
This study investigates level of pollution in the Ajegunle Creek. Water samples were collected and analyzed for five months. This physicochemical characteristics, cation content, nutrients and heavy metal levels varied across the three sampled stations. The mean physicochemical parameters are Temperature (23-29.5ºC), TSS (9-43mg/l), TDS (386.3-15700mg/l), Turbidity (4.92-34.02NTU), Salinity (0.53-8.9%), Conductivity (679.3-25900 µS/cm), DO (0.1-4.8mg/l), BOD5 (2-598mg/l), COD (10-2192mg/l), Total Hardness (82-972mg/l). There were variations in the nutrient values. The mean cation content was; potassium (3.62-151mg/l), Calcium (4.11-170.3mg/l), Silica (0.82-11.43mg/l), Sodium (135.1-4926.07mg/l) and Oil and grease (< 0.2 mg/l). Nitrate ion is the common form of nitrogen found in the study site. The metals concentrations recorded are arranged in order of their distributions in the three sampling stations as follows: Fe>Zn>Mn>Cr>Ni>Cd>Pb>Cu. The seasonal influence as well as human induced stressors in the water confirmed that the Ajegunle creek in the Tin-Can Island area of Lagos is polluted.
Water Pollution Scenario at River Uramurukwa Flowing Through Owerri Metropolis, Imo State, Nigeria (Published)
Pollution scenario of water from River Uramurukwa was investigated. In both rainy and dry season, 5 water samples each taken from different points were analysed to determine physico-chemical parameters and heavy metals (using Atomic Absorption Spectrophotometer). The investigated physico-chemical parameters for both dry and rainy season respectively ranges from: temperature (32-32.4oC, 29-29.8oC), electrical conductivity (15.67-2.00 µS/cm, 7.31-61 µS/cm), pH(5.2-5.7, 5.9-6.7), total dissolved solids (2.67-3.98 mg/L, 3.29-5.33 mg/L) and TSS (4.43-6.64 mg/L,4.88-5.84 mg/L). The analysed major ions were: sodium (Na+)(1.30-1.67 mg/L, 1.76-2.38 mg/L), potassium (K+)(0.819-0.898 mg/L, 0.08-1.89 mg/L), magnesium (Mg2+)(1.13-2.78 mg/L, 1.23-2.86 mg/L), calcium (Ca2+)(22.92-24.6 mg/L, 13.9-43.9 mg/L), nitrate (NO3–)(0.91-0.96 mg/L, 0.56-0.97 mg/L), phosphate (PO43- )(0.34-1.65 mg/L, 1.07-2.17 mg/L) and sulphate (SO42-)(23.4-24.8 mg/L, 21.02-29.18 mg/L). The investigated heavy metals were: lead (Pb), zinc (Zn)(1.2-2.63 mg/L, 1.60-3.33 mg/L), copper (Cu)(0.13-0.79 mg/L,0.001-0.61 mg/L), iron (Fe)(0.091-0.19 mg/L,0.017-1.97 mg/L), cadmium (Cd)(0.002-0.180 mg/L, 0.002-0.025 mg/L), manganese (Mn)(0.08-1.02 mg/L, 0.008-0.091 mg/L). Temperature, Ec, DO,TDS and TSS were found to compile with WHO guidelines for domestic drinking water except for pH. Cu, Mn, Fe, in the water samples were all within the recommended guidelines of FEPA and WHO for domestic water use. High concentrations of Cd, Mn and Fe were observed at point 2 while all points for Zn and Pb exhibited high concentration. Water quality Index showed the area is unpolluted and safe for use. No ecological risk was observed except for Cd and Pb. PLI was all within recommended limit except for point 2 during the dry season. It should be observed that the River is polluted with Cd and Pb, this are highly toxic metals which can cause serious health damages even at low concentration.
Comparative Evaluation of Lycopene and Heavy Metal Contents Of Two Species of Tomatoes Within Awka Metropolis (Published)
Tomato Species belong to edible vegetable fruit obtained from tomato plant which serves as a food source to people irrespective of culture, religion and belief. Two species of the tomato samples were bought from five different local markets within Awka metropolis, Anambra State. The samples were washed with deionised water, and lycopene content extracted using solvent mixture of n-hexane, acetone and ethanol in the ratio of 2:1:1 respectively. The extract was subjected to Uv spectrophotometer for lycopene content at 503nm. The moisture content was examined via difference in weight in an oven at 1050c. The washed samples were blended and digested with acid mixture of 10ml perchloric acid, 25ml concentrated nitric acid and 4ml sulphuric acid. The level of heavy metal in the digest was evaluated using atomic absorption spectrophotometer. The results showed lycopene range of 18.82mg/kg to 98.52mg/kg. The higher concentration of lycopene was associated with Beefsteak species with average value of 73.13mg/kg, while a lower average level of 40.76mg/kg was implicated in cherry specie. Lead was the metal with lowest average concentration of 0.083ppm. The metal with the highest average concentration in the tomato samples was chromium (0.520ppm). The observed trend in the metal concentration for all the samples was Cr (0.520ppm) > Cu (0.493ppm) > Fe (0.453ppm) > Zn (0.421ppm) > Cd (0.121ppm) > Pb (0.083ppm). Only Pb was within the permissible limit as stipulated by WHO (Pb-0.1mg/L), all other metals were above the permission limit as stated by FAO and WHO of 2011. Expectedly the tomato had high moisture content (95.7%). Statistical treatment of the data showed the existence of a strong inverse correlation between Fe and Pb concentration in the tomato sample (r = -710, p = 0.020). There was no statistical correlation between lycopene content and the total metal concentration (r = -0.349, p = 0.324).
Effect of Size on Proximate Composition and Heavy Metal Content of the Mangrove Oyster Crassostrea gasar from the Andoni River, Nigeria (Published)
The proximate composition and heavy metal content of the mangrove oyster Crassostrea gasar from the Andoni River was investigated. Samples were categorized into three class sizes: small (< 25 mm), medium (25-50 mm), and large (> 50 mm) each with 10 sampling units for each class size. Differences across class size were significant for carbohydrate, lipid, and fiber content with their highest mean values recorded as 58.39 ± 0.21%, 6.70 ± 0.10% and 18.22 ± 0.28% respectively. Size-specific differences were detected only for concentrations of lead and zinc which showed maximum concentrations of 0.53 ± 0.02μg/g and 42.69 ± 1.81μg/g respectively. The proximate composition and heavy metal content recorded were generally higher in large-sized oysters and the variations observed were attributed to obvious differences in their class sizes. The remarkably low moisture content recorded in C. gasar was attributed to higher drying temperatures (105°C). Food quality and uptake of heavy metals in tissues of C. gasar generally varied along size gradients, with peak values in large-sized individuals. However, the levels of heavy metals recorded in soft tissues of C. gasar in this study were generally very low and fall within levels expected in tissues of aquatic biota.
Analysis of Heavy Metal Contamination by Artisanal Refining Plants in the Niger Delta Region, Southern Nigeria (Published)
Artisanal refining Plants are common features of the Niger Delta Region of Nigeria. The effects of heavy metal contamination on soil by non-conventional refining plants were investigated and analyzed using standard methods. Two soil samples were collected at 18 m intervals between Plants A and B and at 24 m intervals between Plant B and C. Then control sample was collected 2 km away from unimpacted soil. The result of the analysis showed that polynuclear aromatic hydrocarbon (PAH) recorded maximum concentration of 6899.4942 ppm at station C at the depth of 0-15 cm. Furthermore, the concentration of heavy metals investigated are below critical levels as proposed by FEPA (1991) and NCC(1991).