Heavy metal analyses and nutritional composition of raw and smoked fishes from Ologe and Lagos Lagoon, Lagos, Nigeria

This study was conducted to evaluate nutritional composition and heavy metals concentration of smoked and raw edible fish species from Ologe lagoon (freshwater) and Lagos lagoon (marine). The fish species from Ologe include: Chrysichthys nigrodigitatus (Catfish), Monodactylus sebae (African moony), Pomadasys jubelini (Buro), Sphyraena barracuda (Great barracuda), and Pseudotolithus elongatus (Croaker), while that of Lagos lagoon include Chrysichthys nigrodigitatus (Catfish), Caranx hippos (Crevalle jack), Liza falcipinnis (Sicklefin mullet), Pomadasys jubelini (Buro), and Monodactylus sebae (African moony). The nutritional composition ranged in the following trend moisture (43.24 - 76.79 %) > carbohydrate (3.16 – 63.45 %) > protein (0.80 - 31.55 %) > fibre (1.07 – 2.8 %) > ash (0.81 – 1.88 %) > fat (0.40 – 1.30 %). In this study, these fishes are generally low in fats (lean fish), and fish smoking tend to reduces their nutritional composition. Heavy metals concentration trend thus Zn (2.4 – 7.75 mg/kg) > Ni (0.80 – 1.925 mg/kg) > Cr (0.20 – 0.550 mg/kg) > Pb (0.025 – 0.50 mg/kg). In all the samples, all the metals of interest were detected except cadmium which was not found in any of the samples analysed. Pb (0.025 - 0.5 mg/kg) values in the fishes were lower than the maximum standard level reported to be 0.5 mg/kg dry weight by FAO except in the raw Pomadasys jubelini where the value is 0.5mg/kg. The fresh water fishes showed higher concentration of heavy metals than marine water fishes but not statistically significant (p>0.05). Although, smoked fishes showed higher concentration of heavy metals than the raw fishes, it was only significant for zinc (p<0.05). In view of this study and the importance of fish in human diet, it is recommended that biological monitoring of fishes meant for consumption from these two water bodies be carried out regularly to ensure human safety.Keywords: Nutritional composition, heavy metals, fresh water fishes, marine water fishes, lagoon

Ambient Air Quality Monitoring in Metropolitan City of Lagos, Nigeria

Twenty one sampling locations were assessed for carbon monoxide (CO), carbondioxide (CO2), oxygen (O2), sulphur dioxide (SO2), nitrogen dioxide (NO2), nitrogen oxide (NO), suspended particulate matter (SPM) and noise level using air pollutants measurement methods approved by ASTM for each specific parameter. All equipments and meters were all properly pre-calibrated before each usage for quality assurance. Findings of the study showed that measured levels of noise (61.4 - 101.4 dBA), NO (0.0 - 3.0 ppm), NO2 (0.0 - 3.0 ppm), CO (1.0 – 42.0 ppm) and SPM (0.14 – 4.82 ppm) in all sampling areas were quite high and above regulatory limits however there was no significant difference except in SPM (at all the sampling points), and noise, NO2 and NO (only in major traffic intersection). Air quality index (AQI) indicates that the ambient air can be described as poor for SPM, varied from good to very poor for CO, while NO and NO2 are very good except at major traffic intersection where they were both poor and very poor (D-E). The results suggest that strict and appropriate vehicle emission management, industrial air pollution control coupled with close burning management of wastes should be considered in the study area to reduce the risks associated with these pollutants.© JASEMKeywords: Air, pollutants, Air quality index, carbon-monoxide, sulphur-dioxid

Potential human health risk assessment of heavy metals intake via consumption of some leafy vegetables obtained from four market in Lagos Metropolis, Nigeria

This work investigated six heavy metals (Pb, Cr, Zn, Cd, Ni and Cu) accumulation in five popular leafy vegetables: Telferia occidentalis (fluted pumpkin), Talinum triangulare (waterleaf), Ocimum gratissimum (scent leaves), Celosia argentea (plumed cockscomb), and Amaranthus viridis (slender amaranth) obtained from 4 popular markets in Lagos metropolis using an atomic absorption spectrophotometer (AAS), and evaluate the human health risks of their consumption. Heavy metals content in vegetables across the markets ranged as follow; Cd (0.05 – 0.20 mg/kg); Pb (0.34 – 5.44 mg/kg), Zn (4.21 – 20.80 mg/kg), Cr (0.25 – 1.51 mg/kg), Ni (0.13 – 2.91 mg/kg) and Cu (2.34 – 14.08 mg/kg). The concentrations of all metals are quite generally lower than the permissible levels by FAO/WHO in vegetables except for Pb. Statistical analysis of levels of the studied metals in A. viridis, T. occidentalis, C. argentea, and O. gratissimum in all the markets sample showed significant differences in levels of Zn, Cr, Cu and Ni (p<0.05). To assess the the health risk of the inhabitants of Lagos and the environs due to heavy metal intake from these vegetables consumption., the daily intake of metals (DIM), health risk index (HRI), and target hazard quotient (THQ) were calculated. The daily intake of metals in vegetables species for Zn (0.51 – 1.46 mg/kg) and Ni (0.05 – 0.22 mg/kg) are significantly lower than the recommended daily intake of metals and the upper tolerable daily intake level (UL). However, DIM of Cd (0.004 – 0.017 mg/kg) and Pb (0.046 – 0.182 mg/kg) exceed the recommended DIM but fall within the upper tolerable daily level. Cr (0.048 – 0.082 mg/kg) is lower than the recommended oral reference dose (RFD) of 1.5 mg/kg (USEPA, 2010). The THQ values range showed that Cd was 0.048 – 0.192, Pb was 0.150 – 0.587, Zn was 0.021 – 0.190, Cr was 0.0001 – 0.001, Ni was 0.050 – 0.120 and Cu was 0.148 – 0.239. This result reflected the risk associated with exposure for the period of life expectancy considered, and the inhabitants are highly exposed to health risks associated to these metals in the order Pb > Cu > Cd > Ni > Zn > Cr. The THQ in all metals is less than 1 in all the vegetables species; therefore, it does not pose serious health risk concern. However, vegetable consumption was just one part of food consumption, the potential health risks for residents might actually be higher than in this study when other routes of heavy metals intake are considered.Keywords: Heavy Metals, leafy vegetable, daily intake of metals, health risk index, target hazard quotient (THQ), zinc, lead, chromium, cadmium, nickel, coppe

SPATIAL DISTRIBUTION, DYNAMICS AND MAPPING OF THE SOIL ORGANIC CARBON AND TOTAL NITROGEN DENSITY ESTIMATES IN LAGOS LAGOON WETLANDS

Accurate estimation of wetland carbon densities is a prerequisite for wetland conservation and implementation of carbon sink enhancement plans. This study was designed to investigate spatial distribution in Soil Organic Carbon (SOC) and Total Nitrogen (TN), and Soil Organic Carbon density (SOCD) and Total Nitrogen  density (TND) stocks in Lagos lagoon wetlands and the influence of other soil physicochemical. The SOC content generally exhibited high seasonal variations for all the sampling points in the wetlands. During wet season it ranges from 12.71±0.15 - 164.995±1.65 g/kg with a coefficient of variation of 40.99%, and dry season ranged from 132.02±3.520 - 383.570±8.43 g/kg with a coefficient of variation of 34.45%. The soil carbon content in the wet season was much lower than the dry season. The total nitrogen content in the wet season ranged from 4.53 – 16.58 g/kg with a COV of 27.96%, while the dry season ranged between 10.16 and 40.31 g/kg with a coefficient of variation of 29.39%.The SOC density of Lagos lagoon wetlands for tops soils ranged from 10.53 to 37.89 kgm−2 with an arithmetic mean of 26.70±1.41 kgm−2 and TND ranged from 0.61 to 2.37 kgm−2 with an arithmetic mean of 1.96±0.09 kgm−2. Pearson correlation reveal a positive correlation between SOC and TN (r=0.643), bulk density and SOC (r=0.344), TN and bulk density (r=0.478) and soil moisture and pH (r=0.085). In the present study, a negative correlation was observed in SOC and pH, and TN and pH. The results suggest that nitrogen content, moisture content and bulk density, which are significantly influenced by vegetation, seasons and topography, are some of the factors affecting their accumulation and seasonal variation. Thus, density of nitrogen and carbon in wetlands are important for soil quality. They also influence the carbon and nitrogen sequestration potential as well as reducing atmospheric CO₂ and mitigating the threat of global warming.Background: Soil organic carbon and total nitrogen are important components of wetland soils; they can greatly influence the wetland ecosystem fertility, quality and productivity. Accurate estimation of wetland carbon densities and pools is aprerequisite for wetland resource conservation and implementation of carbon sink enhancement plans. This study was designed to investigate the dynamics and spatial distribution in Soil Organic Carbon (SOC) and total nitrogen (TN), and SOC and TN density stocks in Lagos lagoon wetlands and the influence of other soil physicochemical parameters on them.Results: The SOC content generally exhibited high seasonal variations for all the sampling points in the wetlands. For wet season it ranges from 12.71±0.15 - 164.995±1.65 g/kg with a coefficient of variation of 40.99%, and dry season ranged from 132.02±3.520 - 383.570±8.43 g/kg with a coefficient of variation of 34.45%. The soil carbon content in the wet season was much lower than the dry season. The total nitrogen content in the wet season ranged from 4.53 – 16.58 g/kg with a coefficient of variation of 27.96%, while the dry season ranged between 10.16 and 40.31 g/kg with a coefficient of variation of 29.39%.The SOC density of Lagos lagoon wetlands for tops soils ranged from 10.53 to 37.89 kgm−2 with an arithmetic mean of 26.70±1.41 kgm−2 and TND ranged from 0.61 to 2.37 kgm−2 with an arithmetic mean of 1.96±0.09 kgm−2. Pearson correlation reveal a positive correlation between SOC and TN concentrations (r=0.643), bulk density was positively correlated also with SOC (r=0.344), TN and bulk density (r=0.478) and soil moisture content and pH (r=0.085) were also positively correlated. In the present study, a negative correlation was observed in SOC and pH, and TN and pH. The results suggest that nitrogen content, moisture content and bulk density, which are significantly influenced by vegetation cover and types, seasons and topography, are some of the factors affecting soil organic carbon and nitrogen accumulation and seasonal variation.Conclusion: This study provided an insight in the understanding of the seasonal and spatial distribution of SOC and TN density in the Lagos lagoon wetland. In conclusion, the estimation of the density and storage of nitrogen and organic carbon in the wetlands are important for knowing and maintaining the quality of the soils, and they also influence the carbon and nitrogen sequestration potential of the wetlands as well as reducing atmospheric CO₂ and mitigating the threat of global warming

Study of the time-efficacy and rate of phytoremediation of crude oil polluted soil by Vigna unguiculata (L) Walp.

The use of plants for enhanced remediation of crude oil contaminated soil has been a subject of interest due to the various benefits attributed to it. However, little or no study has focused on determining the time efficacy of plants to enhance high level of remediation and the rate at which phytoremediation of crude oil takes place. This study investigated the time-efficacy of cowpea (Vigna unguiculata) in remediating crude oil contaminated soil and rate of remediation using TPH loss as indicator. Three kilogrammes of soil each were experimentally contaminated with 12.5ml, 25ml, 50ml, 75ml and 100ml of Bonny light crude oil. The cowpea plants were introduced into the contaminated soil and the total petroleum hydrocarbon (TPH) contents were determined on day 0, after 45 days and after 90 days of planting and the pH, moisture content and organic matter content were determined on same days. The concentration of crude oil in the soil affected the efficacy of the remediation and the soils physical and organic properties. Higher levels and faster rates of remediation were obtained in the different treatments of the soil with V. unguiculata than in the soil without the plant. The growth of the plant contributed to faster rates of remediation in the 12.5ml and 25ml crude oil treated soils in the first 45 days than in second 45 day while in the second 45 days, the growth of the plant contributed to faster rate of remediation in 50ml, 75ml and 100ml crude oil treated soils than in the first 45 days. The results suggest that the impact of V. unguculata is higher in the early period for low level of contamination and higher in the later period in the soil with higher level of contamination. The presence of cowpea in crude oil contaminated soil led to improved remediation efficacy of the soil and decrease the time required for remediation to occur thus with the growth V. unguiculata, it will take a shorter period restore crude oil contaminated soil to its good state. It is recommended that cowpea can be combined with other plants or bacteria or organic components that have been known to aid the remediation of crude oil to achieve a higher level of remediation

Physicochemical and Genotoxic Evaluations of Singed Cowhide Meat (Ponmo) Wastewater

Introduction. In spite of doubts over the safety and nutritional benefits of singed cowhide meat, called ponmo in some parts of Nigeria, and its potential negative impact on the hide and leather industry, consumption in Nigeria and many parts of Africa has continued unabated. Objectives. In the present study, physicochemical and genotoxic assessments of wastewater used to rinse ready-to-cook singed cowhide meat were carried out. Methods. Physicochemical analyses were carried out using the American Public Health Association procedures, while genotoxic assessment was carried out using Allium cepa chromosome assay. Results. The results of the physicochemical analyses indicated that some of the parameters, especially metals, were within the threshold of the limits set by the country's regulatory agencies, but some parameters like phosphate, chloride, nitrate, biological oxygen demand, and chemical oxygen demand were higher in concentration. The wastewater inhibited the growth of A. cepa roots and caused a decrease in its mitotic index relative to the control onions exposed to water only. The highest root growth inhibition of 72.14% was induced by a 10% wastewater concentration, while the lowest (53.57%) was induced by a 5% wastewater concentration. In addition, the wastewater induced bi-nucleated, attached, vagrant, C-mitosis, sticky and bridged chromosomal aberrations. Wastewater at a 5% concentration induced the highest significant (P < 0.05) percentage chromosome aberration of 36.62% at 48 hours of exposure. Sticky chromosomes had the highest significant frequency (P <0.01) at the end of the 72-hour exposure period. No chromosomal aberration was observed in the control. Conclusions. These results indicate that singed cowhide meat wastewater is potentially genotoxic and environmentally harmful. Governments, public health practitioners, and relevant stakeholders should work in synergy to discourage the habit of processing cowhide into cowhide meat. Competing Interests. The authors declare no competing financial interests

Phytoremediation of crude oil contaminated soil using glycine max (Merril); through phytoaccumulation or rhizosphere effect?

The aim of this study was to evaluate the process which Glycine max (soybean) uses in the phytoremediation of crude oil contaminated soil. A screen house experiment was conducted with different amounts (25g, 50g and 75g) of crude oil-contaminated soil for 110 days. The initial and final total petroleum hydrocarbon (TPH) contents of the contaminated soils and that in the plant tissues were measured and the bacterial loads and types in the soil samples were determined at the end of the study. The soil pH, moisture and organic matter contents were also determined every 21 days for 110 days. Soil samples for the above analyses were obtained from the soils treated with the various amounts of crude oil with and without G. max (which served as the control). The investigation revealed that the initial TPH values of the soils were higher than the final TPH values and that there were lower TPH values in the soils with G. max compared to soils without G. max. The growth of G. max led to 52.48% reduction against 50.15% reduction in non-vegetated soil, 66.93% reduction against 44.57% reduction in non-vegetated soil and 49.04% reduction against 44.31% reduction in soil contaminated with 25g, 50g and 75g crude oil respectively The bacterial load, pH, moisture content and the organic matter contents of the crude oil contaminated soil were significantly affected by the growth of G. max at different levels of significance (P<0.05; P<0.01; P<0.001). The results of this study have shown that the growth of G. max on crude oil contaminated soil reduces the TPH level, enhances bacterial growth, improves the soil pH and improves the moisture content (for high level contamination). Thus, it is suggested that G. max is a good candidate for remediating crude oil contaminated soil and that it remediates crude oil contaminated soils through rhizospheric effect

Nutritional composition and heavy metal content of selected fruits in Nigeria

Despite the nutritional benefits obtained from fruit consumption, the presence of heavy metals accompanying it from the environment draws scientific concerns as these affect human health. The aim of this study is to determine nutritional composition and heavy metal content of some commonly consumed fruits (apple, watermelon and sweet orange) in Nigeria. Atomic absorption spectrophotometry was used to determine nickel, cadmium, chromium, lead and copper present in fruits. The results obtained show that the three fruit varieties contained considerable nutritional value that may meet body needs. Additionally, there was no significant difference in heavy metal concentrations of the fruits based on different locations (ANOVA F. test >0.05). This study posits that all the fruit varieties had the heavy metals within world health organisation (WHO) permissible limit except apples. Apples sampled for different locations had nickel and chromium levels above the WHO permissible limits. Based on the observations in this study, there is a need for continuity of heavy metals inspection in agricultural products so as to prevent contamination and secure human safety