Bioaccumulation of Polybrominated Diphenyl Ethers in Tilapia guineensis from Lagos Lagoon, Lagos State, Nigeria

Certain pollutants, particularly synthetic organic compounds have given rise to important environmental concerns. New organic pollutants especially polybrominated diphenyl ether (PBDEs) employed in electronic equipment and in some household items as flame retardants are now finding their way into the aquatic environment as components of waste discharge into the water body. These highly hazardous organic pollutants of concern are persistent, can bioaccumulate and biomagnify in aquatic organism especially fish, and there appears to be no clear strategy for managing them. In this study, levels of polybrominated diphenyl ethers were determined in sediments collected from Lagos lagoon with the aim of generating a database which can be employed for management options. Sediment samples were collected using Van Veen grab for a period of one year from randomly selected sites in Lagos lagoon. The samples were soxhlet extracted with dichloromethane to obtain PBDEs extracts which were later cleaned up in a column of silica gel using hexane as eluant. The cleaned extracts were analyzed using gas chromatography coupled with electron capture detector. The total concentrations of PBDEs in sediments ranged from 0.11 to 23.33 mg/kg. In all the studied locations, BDE-28, BDE-153, BDE-154 and BDE 205 were detected in all sediment samples at concentration range of 0.22 to 23.33 mg/kg. Among the PBDEs congeners, sum of tri to hepta BDEs contributed 61.32%, while BDE-205 contributed 38.68% to the total PBDE in the sediment samples. Brominated congeners BDE-47, BDE-153 and BDE-154 (tetra and hepta BDEs) were abundant which contributed 18.31, 12.06 and 34.75%, respectively to the sum of tri to hepta BDE in the sediment. The composition patterns of PBDEs in Lagos Lagoon sediment samples revealed that technical deca-BDE mixture was the major pollutant sources with a minor contribution of penta-BDE mixture. Key words: Gas chromatograph, polybrominated diphenyl ether (PBDEs), sediment, Lagos Lagoon

Lagos State is endowed with international commerce, industry and infrastructure excellence drives. In Lagos State, traffic situation is chaotic and socio-economically unfriendly due to ills in multi-transportation modal functions. Urgent research and development attention is required to arrest total collapse of the entire modal system. In this study, a framework is developed for efficient utilization of Lagos waterway system as a complement to other transportation modes such as the dominating road mode. The paper has used passengers travel distances, travel times, travel delays and speed variations on road and water transportation systems in Lagos State to design a geographic information system (GIS) of waterway transportation system. This attempt has formed its base on graph theory, spatial interaction and urban transit capacity. The study has also designed a vector-based GIS for four (4) different spatial locations of the water transportation route network. Consequently, the water transportation at a peak hour commuter service that would complement existing bus, car and taxi in order to reduce the demand for road transportation in Lagos Metropolis was examined. From the study, water transport is found to have caused a reduced journey time by an average of 46.33%. Key words: Traffic, graph theory, passenger travel distances, travel times, waterways.

The study evaluates the economic performance of small-scale crab fishery operations in terms of economic indicators and success performance during 2009 and 2010 fishing season in five lagoon systems in Lagos state. The objectives of the study were to state economic viability of the crab fishing activity and to identify factors influencing the cost structure. Initial analysis reveals that a large variation in cost structure exists in the crab fishing in Lagos lagoon. Economic results of the study showed that small-scale crab fishing have a positive net profit and fully recover their costs, with no losses. The net cash flow, economic and financial performance of the crab fishers was very satisfactory. The result shows that increasing catch decreases costs implying that scale and improving efficiency is key to reducing cost. Key words: Crab fishery, economic viability, economic performance, returns on capital, Lagos lagoon.

Lagos Lagoon is a very popular lagoon in Lagos state that receives effluents from neighboring industries. These effluents tend to increase the level of contaminants in the lagoon, thereby creating more stressors for aquatic animals. Determination of polycyclic aromatic hydrocarbons (PAHs) in four commonly consumed fish species from the lagoon and the prediction of possible health risks associated with their consumption were performed in this study. Various levels of PAH were detected in the fish tissues with the highest total concentration of PAH in Sarothoredon melanotheron. High concentrations of benzo(a)pyrene were noticed in Sarothoredon melanotheron and Ethmalosa fimbriata, and their values were above the guideline value of 0.002 μg/g. The dietary daily intake (DDI) value in S. melanotheron 82.00 ×10-5 μg/g/day was highest. Carcinogenic toxic equivalents (TEQ) showed that consumption of S. melanotheron had higher potential to pose carcinogenic risks, while the excess cancer risk (ECR) index for the PAHs in all the assessed fish species was beyond threshold values indicating potential carcinogenic risk from their consumption. No significant association was found between the concentration of PAHs and the size of the fish. Target hazard quotient (THQ) results suggested absence of potential non-carcinogenic risk if individual PAH in the fish are consumed frequently. The study however established possible carcinogenic human health risk from consumption of the fish obtained from Lagos Lagoon. The study recommends monitoring of contamination and consumption of fish from harvest sites within the study region.

Certain pollutants, particularly synthetic organic compounds have given rise to important environmental concerns. New organic pollutants especially polybrominated diphenyl ether (PBDEs) employed in electronic equipment and in some household items as flame retardants are now finding their way into the aquatic environment as components of waste discharge into the water body. These highly hazardous organic pollutants of concern are persistent, can bioaccumulate and biomagnify in aquatic organism especially fish, and there appears to be no clear strategy for managing them. In this study, levels of polybrominated diphenyl ethers were determined in sediments collected from Lagos lagoon with the aim of generating a database which can be employed for management options. Sediment samples were collected using Van Veen grab for a period of one year from randomly selected sites in Lagos lagoon. The samples were soxhlet extracted with dichloromethane to obtain PBDEs extracts which were later cleaned up in a column of silica gel using hexane as eluant. The cleaned extracts were analyzed using gas chromatography coupled with electron capture detector. The total concentrations of PBDEs in sediments ranged from 0.11 to 23.33 mg/kg. In all the studied locations, BDE-28, BDE-153, BDE-154 and BDE 205 were detected in all sediment samples at concentration range of 0.22 to 23.33 mg/kg. Among the PBDEs congeners, sum of tri to hepta BDEs contributed 61.32%, while BDE-205 contributed 38.68% to the total PBDE in the sediment samples. Brominated congeners BDE-47, BDE-153 and BDE-154 (tetra and hepta BDEs) were abundant which contributed 18.31, 12.06 and 34.75%, respectively to the sum of tri to hepta BDE in the sediment. The composition patterns of PBDEs in Lagos Lagoon sediment samples revealed that technical deca-BDE mixture was the major pollutant sources with a minor contribution of penta-BDE mixture. Key words : Gas chromatograph, polybrominated diphenyl ether (PBDEs), sediment, Lagos Lagoon.

This paper investigated awareness and adoption levels of improved smoking oven among fish processors in four fishing communities along Lagos Lagoon, Nigeria. Multi-stage sampling procedure was used to select 153 respondents who were engaged in fish smoking. Data collected using structured interview guides were subjected to descriptive and inferential analyses. Results revealed that majority of the respondents were young, married women with average fish smoking experience of 22.6 years. Majority (90.8%) of them were solely engaged in fish smoking while 9.2% combined fish smoking with other income-generating activities. All the processors used traditional smoking oven (drum, box and mud ovens). More than 66.0% of the fish processors were not aware of improved fish smoking equipment. Lack of awareness, inadequate access to the technologies, low relative advantage and lack of maintenance services and high cost of procurement were responsible for low adoption levels of improved smoking oven. Irregular visits of extension agents to the study area had negative impact on the adoption of improved traditional smoking ovens. Proper dissemination of innovations developed on improved fish processing equipment to the active fish processors in Lagos State using available communication channels is hereby advocated.

The potential environmental impact of sediment-bound Cd, Cr, Cu, Pb and Zn in three trans-urban rivers in Lagos state and in the Lagos Lagoon was assessed by use of the modified Community Bureau of Reference (BCR) sequential extraction. The quality of the data was checked using BCR CRM 143R and BCR CRM 701. Good agreement was obtained between found and certified/indicative values. Of the rivers, the Odo-Iyaalaro, was generally the most contaminated and the Ibeshe the least. Higher concentrations of metals were generally found in the dry season compared to the wet season. Cadmium and Zn were released mostly in the acid exchangeable step of the sequential extraction, indicating that they have the greatest potential mobility and bioavailability of the analytes studied. Chromium and Cu were associated mainly with the reducible and oxidisable fractions, and Pb predominantly with the reducible and residual fractions. Sediments with the highest pseudototal analyte concentrations also released higher proportions of analytes earlier in the sequential extraction procedure. The study suggests that, during the dry season, potentially toxic metals (PTM) may accumulate in sediments in relatively labile forms that are released and can potentially be transported or bioaccumulate in the rainy season. Application of risk assessment codes and Hankanson potential risk indices indicated that Cd was the element of greatest concern in the Lagos Lagoon system. The study indicated that there is a need to strengthen environmental management and pollution control measures to reduce risk from PTM, but that even relatively simple strategies, such as seasonal restrictions on dredging and fishing, could be beneficial.

Organochlorine pesticides (OCPs) have been of great concern around the world owing to their chronic toxicity, persistence and bio-accumulation in aquatic organisms. The OCP concentrations were measured in water, sediment and shell fishes (Panaeus monodon and Callinectes pallidus) in Lagos State (Lagos lagoon and Badagry creek), between November 2018 and June 2019. The samples were analyzed for Alpha (HCH), Beta (HCH), Gamma (HCH), Delta (HCH), Heptachlor, Aldrin, Heptachlor epoxide, Gamma chlordane, Endosulfan1 Alpha chlordane, Dieldrin, DDE, DDD, DDT, Endrin, Endosulfan II, Endrin Aldehyde, Endosulfan sulfate, Endrin ketone and Methoxychlor. The detection and determination of the pesticide residues were carried out by Gas chromatography with electron capture detector. The mean concentration of OCPs in water samples ranged from 0.150 ± 0.012µg/l (Alpha HCH) to 147.60 ± 10.810 µg/l (Endosufan II). The level of OCPs in sediment ranged from 0.150 ± 0.012 µg/kg (Alpha HCH) in Lagos lagoon to 243.500 ± 138.000 µg/kg (ppDDT) in Badagry creek. The highest mean concentration of OCPs in water and sediments were recorded in Lagos lagoon. The Concentration for shell fish ranged from 0.250 ± 0.009 µg/kg (Alpha HCH) in Lagos lagoon to 67.380 ± 22.860 µg/kg (Endosulfan II) in Badagry creek for Callinectes pallidus and from 1.310 ± 0.210 µg/kg (alpha HCH) to 143.500 ± 71.892 µg/kg (Eldrin Aldehyde) in Badagry creek for Penaeus monodon. Methoxychlor, Lindane and Aldrin were the commonly detected compounds in all the samples from both water bodies. The results showed that OCP levels in all shellfish samples analyzed were above the maximum acceptable limits of 0.01ppm (10 µg/kg) set by EU and Federal Ministry of Environment for aquatic life protection. The highest value was recorded in Penaeus monodon in Badagry creek. Indicating an urgent need for the monitoring of these pesticide residues in water, commercially important food species and the environment, as this will go a long way towards preventing various environmental and public health hazards.

Environmental risk perception of stakeholders for various human activities is germane to the sustainable development of a society. In urban Africa, rising population rates pose environmental challenges for the management of aquatic resources. Examples of two metropolitan cities in urban Africa are Lagos and Ogun states, Nigeria, with their teeming populations. The proximity of the Lagos lagoon and Ogun River to human settlements predisposes their use as sinks for disposal of wastewaters from potentially polluting activities such as sawmills and livestock processing (abattoirs). This chapter evaluates the environmental risk perception of specific stakeholders in the states whose activities result in potential adverse impact on aquatic ecosystems and associated ecosystem services. Copies of a structured questionnaire were administered to stakeholders at selected anthropogenic sites, i.e. Okobaba Sawmills and Kara Cow Market, in Lagos and Ogun states respectively. At the Okobaba sawmills adjoining the Lagos lagoon, respondents stated that sawdust is the major (84%) waste generated, most (90%) of which is burnt. Over half (51–90%) of the respondents noted that air quality, water quality and aquatic animals are adversely impacted by the sawmill activities. At Kara Cow Market, which adjoins Ogun River, respondents reported that they utilise the river for domestic activities, such as source of drinking water and for washing of cows. Most respondents (70–82%) acknowledged that the river is polluted, wastes are deliberately disposed into the river and wastewater from the abattoir is never treated. It is suggested that stakeholder environmental education, advocacy, risk communication, as well as demand for, and implementation of, evidence-based policies for the management of these ecosystems are crucial steps to be taken in addressing the situation. Further, the planning of human settlements near aquatic ecosystems should be considered alongside the sustainability of aquatic resources and ecosystem services in urban Africa, given the need to support life below water (UN SDG 14).KeywordsAquatic ecosystemsSawmill wastesAbattoir wastewaterStakeholders’ environmental risk perceptionSustainable Development Goal 14

Owode, a sprawling water catchment area better known for its commercial activities in metal and iron casting and fabrication, is located off the Lagos Lagoon and the Ajuwon River, in Lagos State. The extensive iron and steel work along with seasonal flooding of the area and the habits of the people in this area is considered a threat to its groundwater integrity. Samples designated SW1, SW2, and SW3 for stream water WW1, WW2, and WW3 for well water and BH1, BH2, and BH3 for samples collected from boreholes were collected and analyzed to determine the presence of certain physicochemical elements and heavy metals. Including pH, EC, TDS, DO, SO42-, Cl, NO3-, and PO43-. Heavy metals analyzed include Fe, Pb, Zn, Cu, Cr, Cd, and Mn. The findings showed that while a number of parameters when compared with the WHO and NADWQ stipulated maximum acceptable concentration fell within acceptable limits, others especially the heavy metals had trace elevations above the maximum acceptable levels which if not checked could have serious future groundwater contamination implications.

The impact of shipping operations on the level of trace metals along the Commodore Channel of the Lagos lagoon is a topic that requires careful consideration. Shipping activities can have a significant impact on the water quality of the lagoon, which in turn can affect the health of the flora and fauna that depend on it. This study attempts to assess the impact of shipping operations on the level of trace metals along the Commodore Channel of the Lagos lagoon. Concentrations of trace metals in the Lagos Lagoon specifically the Commodore channel were determined in March 2016, and the downstream variation was compared. Trace metals (Pb, Cd, Fe, Zn and Co) were determined using Atomic Absorption Spectroscopy (AAS). The concentration of trace metals were found to be beyond the permissible limits stipulated by World Health Organization (WHO) and European Union (EU). There exists an exception in the mean level of Zn (0.23±0.1107mg/L) in the harbor water which was lower than the WHO standard of 5mg/L as at the time of this study. The trace metals showed the decreasing order of Pb > Fe > Zn > Co > Cd with concentration of 1.0±0.6mg/L, 0.62±0.2mg/L. 0.23±0.1107, 0.14±0.12mg/L and 0.05±0.02mg/L respectively. The result of contamination factor showed the harbor water had very high degree of Pb and Cd contamination. This high CF can be caused by the shipping and vessel transportation route and gateway of the harbor into the country. Continuous monitoring is required to assess environmental quality and adopt suitable management techniques in order to prevent the negative impacts of shipping operations on trace metal occurrence in harbors.

Source apportionment, ecological and health risk assessment of potentially toxic elements in water, sediment and blackchin tilapia {Sarotherodon melanotheron (Rüppell 1852)} from Lagos and Ologe Lagoons, Lagos State, Nigeria

Relevance of joint action toxicity evaluations in setting realistic environmental safe limits of heavy metals

In order to make Lagos state a clean and habitable environment, successive democratic governments since 1999 have introduced ‘megacity policy’. The most important of government initiatives of the megacity agenda are constructions of all major and access roads, provision of beautiful surroundings and landscapes and the building of the Lagoon city in the sand-filled areas along the Atlantic Ocean and Lagos lagoon. Government official have consistently claimed that Lagos Megacity project isto provide infrastructure and make the city habitable for low, medium and high income workers and the elites. However big projects were mainly provided in selected areas in the Lagos Island, mainland and other areas where the elites and the rich live. Shanty towns, ghettoes and slums where most Lagos workers live have not really beneffited. This paper examines the challenge which increasing povertyposes to the megacity project. Descriptive method is employed to assess poverty among the Lagos workers. Residential areas were randomly selected and official records were used. Worker’s income is assessed based on prevailing inflation and average earned wages, 672 households’ headsin VIP areas and 1537 in ghettoes, slums and shanty towns were interviewed for the study for two days in week for 24 months between 2015-2017. Affordability of foods, housing, access roads, hospital, schools, sewage system, toilet facilities, waste and refuse disposal and others were used formulate questions directed to measure the wellbeing of individual households of Lagos workers. Findings reveal that governments Lagos megacity projects have led to the provisions of many infrastructures and social services such as roads, schools, hospitals, housing and beautiful landscapes in few areas in the main city, but government efforts to provide the same in all identified ghettoes, slums and shanty towns that dotted many areas in the suburbs where most of the low income workers live have not been quite effective. The paper concludes that megacity projects have not really improved the wellbeing of the Lagos workers. The paper recommends that government should implement megacity policy to improve the wellbeing of large section of its increasing population most especially poor workers in order to reduce the present and future ugly effect of poverty in Lagos state.

Water current modelling and prediction techniques along coastal inlets have attracted growing concern in recent years. This is largely so because water current component continues to be a major contributor to movement of sediments, tracers and pollutants, and to a whole range of offshore applications in engineering, environmental observations, exploration and oceanography. However, most research works are lacking adequate methods for developing precise prediction models along the commodore channel in Lagos State. This research work presents water current prediction using Artificial Neural Networks (ANNs). The Back Propagation (BP) technique with feed forward architecture and optimized training algorithm known as Levenbergq-Marquardt was used to develop a Neural Network Water Current Prediction model-(NNWLM) in a MATLAB programming environment. It was passed through model sensitivity analysis and afterwards tested with data from the Commodore channel (Lagos Lagoon). The result revealed prediction accuracy ranging from 0.012 to 0.045 in terms of Mean Square Error (MSE) and 0.80 to 0.83 in terms of correlation coefficient (R-value). With this high performance, the Neural network developed in this work can be used as a veritable tool for water current prediction along the Commodore channel and in extension a wide variety of coastal engineering and development, covering sediment management program: dredging, sand bypassing, beach-contingency plans, and protection of beaches vulnerable to storm erosion and monitoring and prediction of long-term water current variations in coastal inlets.
 Keywords: Artificial Neural Network, Commodore Channel, Coastal Inlet, Water Current, Back Propagation.