Occurrence, distribution, source apportionment, ecological and health risk assessment of heavy metals in water, sediment, fish and prawn from Ojo River in Lagos, Nigeria.

The study investigates the occurrence and bioaccumulation of heavy metals in water, sediment, fish, and prawn from the Ojo River with a view to identify the source of origin and the associated ecological and human health risks. The result shows that heavy metal concentrations in water [As = 0.010, Cd = 0.001, Cr = 0.041, Cu = 0.019, Co = 0.050, Fe = 0.099, Pb = 0.006, Ni = 0.003, and Zn = 0.452(mg/L)] were within the acceptable limits. The heavy metals in the sediment [As = 0.050, Cd = 0.287, Cr = 0.509, Cu = 0.207, Co = 0.086, Fe = 33.093, Pb = 0.548, Ni = 0.153 and Zn = 4.249 (mg/kg)] were within their respective background levels or earth's crust and the TEL and PEL standard limits. The bioaccumulation of heavy metals in fish and prawn tissues are in this hierarchical form: Fe > Zn > Cu > Cr > Ni > Co > Pb > Ar > Cd and Fe > Zn > Cu > Cr > Pb > Ar > Ni > Co > Cd, respectively. The bioaccumulation factors of heavy metals in fish ranged from 0.893 - 16.611 and 1.056 - 49.204 in prawn, which were higher than the biota-sedimentation factors (BSAF) values, inferring that the fish and prawns of this study ingested heavy metals highly from water column. The aggregated BSAF scores (fish = 5.584 and prawn = 9.137) showed that these organisms are good concentrators of heavy metals in sediments. The water quality index and other pollution indices (Single pollution index, Heavy metal assessment index, and Heavy metal pollution index) demonstrates slightly clean water, with a moderate level of contamination. The HI values of heavy metals in water, fish, and prawn were lower than 1, implying non-carcinogenic risk in children or adults. The ADD and EDI values of the metals were within their respective oral reference doses (RfD). The TCR values showed that exposure to water, either by ingestion or dermal absorption and the consumption of P. obscura and M. vollenhovenii from the Ojo River would not induce cancer risks in people, though As, Cr, Cd, and Pb showed carcinogenic potentials. The sediment contamination indices such as CF, mCd, EF, and Igeo showed a moderate level of pollution. The ecological risk values (NMPI, mCd = 0.068, PLI = 0.016, and R.I = 86.651) of heavy metals implies "no-moderate risk" except for Cd, which showed high risk. The ecotoxicological parameters,  m-PEL-Q (0.024) and m-ERM-Q (0.016) denotes low contamination and no probability of acute toxicity. The CV analysis showed high dispersions and variabilities in the distributions of the heavy metals in water. Other source analyses (Pearson's correlation matrix, PCA, and HCA) showed that both natural processes and anthropogenic activities are responsible for the occurrence of heavy metals in water and sediment from the Ojo River.

Multi-metric Ecosystem Health Assessment of Three Inland Water Bodies in South-west, Nigeria, with Varying Levels of Sand Mining Activities and Heavy Metal Pollution.

This study was conducted to determine the health status of three water bodies (Badagry Creek, Ologe Lagoon and River Owo) exposed to varying degrees of sand mining activities and industrial pollution. Water, sediment and fish samples were collected monthly from the three water bodies between April 2019 and March 2020. Standard methods were used for the analysis of physico-chemical parameters, fish diversity indices, length-weight relationship, condition factor, sediment pollution indices, ecotoxicology of heavy metals in sediment, potential ecological risks and health risk assessment of heavy metals. Positive matrix factorization (PMF) was used to identify and quantify metal source. Shannon's diversity index (H') and condition factor varied between 2.03-2.37 and 0.84-4.86 respectively. Enrichment factor had a range of 4.05×10-4-8.65×10-1, while geoaccumulation index varied from -12.14 to -0.38. The mean quotients using the probable effect level (m-PEL-Q) are 3.91×10-4, 4.77×10-4 and 7.87×10-4 for Ologe Lagoon, Badagry Creek and River Owo respectively. The trend was the same with mean quotients using effect range-median (m-ERM-Q). The estimated dietary intake ranged from 0.00 mg/kg/day in Pb from River Owo to 1.15 × 10-3 mg/kg/day in Fe still from River Owo. The range of values of the target hazard quotient of the metals in Badagry Creek, River Owo and Ologe Lagoon are 1.23×10-4-1.65×10-2, 0.00-1.64×10-2 and 5.76×10-5-1.65×10-2 respectively. PMF identified three sources of metal into the aquatic ecosystems: agricultural, industrial and geological inputs. The study showed that the three aquatic ecosystems are healthy but require regular monitoring to promptly detect sudden changes in their health status.

Heavy metal accumulation in organs of Oreochromis niloticus (Linnaeus, 1758) from industrial effluent-polluted aquatic ecosystem in Lagos, Nigeria.

The concentrations of four heavy metals (Zn, Fe, Cu, and Pb) in water, sediment, and tissues (gill, muscle, brain, and intestine) of Oreochromis niloticus from a segment of the Lagos Lagoon complex were monitored for 10 months (July 2012-April 2013) spanning wet and dry seasons. Three sampling stations were selected: Ologe Lagoon, the nearest to the point where effluent is discharged from Agbara Industrial Estate, the Owo River is upstream before the point of discharge of industrial effluent, and Etegbin is downstream. In most cases, the highest concentrations of heavy metal in fish tissues were recorded in samples obtained from Ologe Lagoon. The ranges of concentrations of heavy metals in the tissues of the fish were 4.06 ± 2.45-49.94 ± 13.11, 81.27 ± 28.52-2044.64 ± 554.77, 10.90 ± 7.69-41.10 ± 11.24, and 0.12 ± 0.07-1.81 ± 3.12 mg/kg for Zn, Fe, Cu, and Pb, respectively. There were significant negative correlations (lowest; r = -0.24, p < 0.01, n = 30; highest; r = -0.58, p < 0.01, n = 30) between fish tissue metal concentrations and size of fish from Ologe Lagoon. Also, significant positive correlations (lowest; r = 0.48, p < 0.05, n = 30; highest; r = 0.93, p < 0.01, n = 30) between concentrations of Cu in sediment and tissues of O. niloticus were observed. The concentrations of the metals in the tissues of O. niloticus have exceeded the limits recommended by WHO. The maximum safe daily consumption (MSDC) value of Fe in Ologe Lagoon was lower than the recommended average daily intake of fish for humans. This indicated that O. niloticus from Ologe Lagoon may not be safe for human consumption. Therefore, there is a need for regular monitoring of heavy metal in these water bodies and enforcement of existing laws on the treatment of effluent before they are discharged into aquatic ecosystems.

Accumulation of Heavy Metals by Wild Mushrooms in Ibadan, Nigeria.

BACKGROUND: Many companies in Nigeria generate industrial effluents, including heavy metals. These metals can be accumulated by biota such as mushrooms, which are then eaten by the populace. OBJECTIVES: The present study investigates the metal content of wild mushrooms in order to educate the local population on the safety of their consumption. METHODS: Seven different species of wild mushrooms (Cortinarius melliolens, Chlorophyllum brunneum, Pleurotus florida, Volvariella speciosa, Cantharellus cibarius, Entoloma spp and Coprinus africana) growing in Ibadan, southwest Nigeria were analyzed for their heavy metal (copper (Cu), cadmium (Cd) and lead (Pb)) contents using atomic absorption spectrophotometry. RESULTS: The concentrations of the heavy metals in the mushrooms and substrate varied by site of collection. The highest concentrations of Cu (92.31±8.42 mg/kg), Pb (76.00±9.78 mg/kg) and Cd (92.45±12.34 mg/kg) were obtained in C. africana, P. florida and V. speciosa, respectively. The lowest contents of Cu (56.00±5.02 mg/kg), and Cd (67.92±5.89 mg/kg) were obtained from C. melliolens, while C. cibarius had the lowest concentration of Pb (40.00±3.56 mg/kg). The highest concentrations of Pb (20.40±3.43 mg/kg) and Cd (26.40±4.34 mg/kg) were obtained in the substrate of C. molybdites, while the lowest Pb (12.40±2.12 mg/kg) and Cd (18.00±3.90 mg/kg) occurred in V. speciosa and C. cibarius, respectively. The bioaccumulation factors of the mushroom species studied ranged from 2.84 - 14.60. CONCLUSIONS: The present study found that heavy metal accumulation varied by species of mushroom, metal content of the substrate and the bioavailability of the metal in the mushroom. The level of metals in mushrooms in the present study was relatively high. Therefore, cultivation of mushrooms in heavy metal-free soil should be encouraged.

Does fertilizer (N15P15K15) amendment enhance phytoremediation of petroleum-polluted aquatic ecosystem in the presence of water hyacinth (Eichhornia crassipes [Mart.] Solms)?

This study investigated the effects of inorganic fertilizer (N15P15K15) amendments on crude oil uptake by water hyacinth. Experimental units (water hyacinth grown in fresh water) were spiked with 0, 20, 40 and 60 mg/L crude oil. After 24 h, they were randomly assigned fertilizer (N15P15K15) at three different concentrations; 0, 6 and 10 mg/L. Crude oil degradation and absorption were determined by measuring total petroleum hydrocarbon (TPH) in the water column and water hyacinth, respectively. The measurements were taken monthly for six months (February-August 2010). The results showed that TPH concentration in the water column in the treatment amended at 6 mg/L (0.30 ± 0.01 mg/L) was significantly lower (p < .05) than the treatment amended at 10 mg/L (0.76 ± 0.15 mg/L) but was similar to the control (0.33 ± 0.03 mg/L). The water hyacinth in the control (phytoremediation) absorbed significantly higher (p < .05) TPH than the fertilizer-amended treatments. The first-order kinetic model gave a better description of the degradation of petroleum hydrocarbons. The study showed that phytoremediation of crude oil by water hyacinth and biostimulation with fertilizer (N15P15K15) is possible.