Appraisal of the Hydrological Potential of Ungauged Basin Using Morphometric Parameters

Discharge data for most basins in developing countries are lacking or inadequate where available. An alternative is to find other ways of appraising the natural water potential of basins without stream discharge records. This study attempts an appraisal of the water resource potential of the Eze-Aku basin in Ebonyi State of Nigeria using morphometric indices alone. From its morphometry the basin is essentially a low land and erosional surface. This affects both the quantity and quality of water for use by inhabitants of the basin. The analysis of results show the Eze-Aku basin is not suitable for water resources development projects demanding large monthly and annual discharge volume such as hydropower and navigation. Other morphometric parameters investigated in the study include bifurcation, shape, stream and drainage densities. Analyses of these parameters provide the basis for demonstrating the effects of environmental controls on both the basin stream network system and for predicting the basin’s output variables. Such information are essential and provide framework for improving agricultural activities, flood control and  management measures and potable water supply in the study area for increased standard of living in the agricultural dominated area.Key words: Discharge, Morphometry, Water Resources Management and  Planning

Acute and chronic effects of organophosphate pesticides (Basudin) to amphibian tadpoles (Ptychadena bibroni)

Toxicity of basudin (an organophosphate pesticide) on the larval stages of the dominant amphibian; Ptychadena bibroni of the Niger Delta ecological zone of Nigeria was assessed using acute and chronictoxicity in the laboratory. Mortality and body glycogen levels were used as ecological endpoints. The American society of testing and material (ASTM) recommended semi-static renewal bioassay wasemployed and LC50 was measured at 96 h. The amphibian larval stages were exposed to basudin concentrations of 0.1, 1.0, 10.0 and 25 ug/l. Derived 96 h LC50 values decreased with increased exposureduration. Estimated 96 h LC50 was 0.860 ug/l. Substantial mortality and incidence of abnormal avoidance response occurred more at higher concentrations. Body glycogen levels in all test concentrations were significantly different between the test and the control experiments at

Levels and human health risk assessment of persistent organics, metalloid and heavy metals in fish

Concentrations of Persistent organics (Polycyclic aromatic hydrocarbons  (PAHs), polychlorinated biphenyls (PCBs), metalloid (As) and heavy metals (Fe, Zn, Mn, Cu, Ni, Cd. V, Cr, Pb, Hg) were measured in fish (Clarias  gariepinus) samples collected from selected stations (S1, S2 and S3) along the stretch of Ovia River, Southern Nigeria, to assess the potential risks to humans consuming fish from the river. Acenaphthylene (AcPY), PCB 18 and iron (Fe) were the most dominant residues with mean concentrations ranging from 0.002 to 0.128, 0.001 to 0.003 and 175.97 to 255.52 mg/kg respectively. The most carcinogenic PAH, Benzo(a)pyrene (BaP) in S3, all the PCB congeners, cadmium (Cd), and lead (Pb) concentrations in the three stations were observed to be above EU recommended guideline values for food safety. Concentrations of dioxin‐like PCB congeners, 77, 105, 114 and the sum of carcinogenic PAHs also contributed to the toxic burden of these contaminants in fish. The estimated cumulative THQ for the assessed metalloid and heavy metals indicates health risks from exposure to metalloid and Heavy metals through fish consumption.Keywords: Fish, PAHs, PCBs, Metalloid, Heavy metals, Health Ris

Rainfall Erosivity in Southeastern Nigeria

In developing land management plans to minimize erosion problem, it is imperative to provide quantitative information on aggressiveness of storms for identifying areas in the landscape which are sensitive to disturbances. The study established that rainfall erosivity (R) indices over Southeastern Nigeria range from very low to very high erosivity. Periods of very low erosivity coincided with the dry season months in the region while the very high R coincided with the rainy season peak periods (June-September). Calabar Owerri and Port-Harcourt recorded the highest erosive storms/ more months of very high erosivity index. The deterministic  relationship between kinetic energy of rains and erosivity pattern observed for the different stations showed that erosive rains contribute significantly to detachment of soil materials in the study area. The need for proper land use management and maintenance of surface vegetal covers cannot be overemphasized with increased weather variability. Monitoring of hydrologic regime and climate –related factors in the region as well as defining areas most vulnerable to erosion would help in erosion disaster management.Keywords: soil erosion, erosivity Index, land use management and rainfal

Human Health Risk Assessment of PAHs in Fish and Shellfish from Amariaria Community, Bonny River, Nigeria

The concentration of polycyclic aromatic hydrocarbons (PAHs) in Fish (Mullet fish-Mugil cephalus) and Shellfish (Tiger prawn-Penaeus Monodon and crab-Uca tangeri) samples from fishing areas in Amariaria Community, downstream of Bonny River, Southern Nigeria, were assessed to determine possible human health risk associated with consumption. Mean levels (mg/kg) of total PAHs ranged from 0.059 to 0.126 in fish, 0.015 to 0.106 in prawn and 0.057 to 0.063 in crab. A considerable predominance of the 3 and 4-rings PAHs in all the matrices was observed with benzo (a) anthracene dominating in all three species. Estimated daily intake (EDI) of PAHs through consumption of fish ranged from 0 to 0.0005 mg/kg/day, for prawn, 0 to 0.0002 mg/kg/day and for crab, 0 to 0.0002 mg/kg/day. EDI values were, however, lower than the reference dose (RfD) indicating low risk from consumption. Results of the estimated excess cancer risk (ECR) for Benzo (a) anthracene in fish, however, suggests that lifetime exposure to Benzo (a) anthracene through fish consumption would result in cancer risk

Modelling Effluent Assimilative Capacity of Ikpoba River, Benin City, Nigeria

The sheer display of reprehensible propensity on the part of public hospitals, abattoirs, breweries and city dwellers  at large to discharge untreated waste, debris, scum and, in particular, municipal and industrial effluents into Ikpoba River has morphed into a situation whereby the assimilative capacity of the river has reached a record level. The seeming quietism and clinical posture of the relevant Environmental Agency to this pathological condition is sickening and in any case seen as remiss on their part. This paper seeks to determine the assimilative capacity of the river with a view to articulating policy-proposal stream in the instance that its value is unsafe for ichthyofaunal beings and humans.  A combination of basic Streeter-Phelp equation and monograph of Fair et al. were used for the determination of the assimilative capacity and the maximum allowable biological oxygen demand (BOD) load discharged into the river from three identified point sources of wastewater and for three different seasons in Nigeria (i.e. rainy, dry and harmattan seasons). Results indicate that in all the segments studied, the Fair ratio (self-purification factor) is less than unity, indicating the predominance of deoxygenation rate over reaeration rate. Reaeration rate ranges over all real values from 0.641day-1to 0.693day-1, while deoxygenation rate ranges between 0.718 day-1 and 0.839 day-1; a condition which indicates a poor assimilative capacity potential. Moreover, a higher assimilative capacity was obtained for rainy season for all the segments studied, with sampling point 3 (Guinness-harmattan and dry season) showing an overall worse assimilative capacity and poor maximum allowable BOD of 8.1x109, 1.28x1010 and 5.60x109 kg/day respectively. In a way, the determination of the assimilative capacity of Ikpoba River is a landmark in the history of the river pollution. It beggars belief that we live down the harrowing pathological condition of the river without recognizing its wider implications.http://dx.doi.org/10.4314/njt.v34i1.1

Physicochemical and bacteriological characteristics of rainwater harvested from rooftops in Esan-West Local Government Area of Edo State, Nigeria

Due to scarcity of potable water, rainwater harvesting from rooftop has been favoured as an alternative source of water supply by most rural communities in Nigeria. This study investigated the physicochemical and bacteriological characteristics of rainwater harvested from three different rooftop sheets in Esan West Local Government Area, Edo State. Parameters investigated include pH, TSS, TDS, Turbidity, Acidity, Ca2+, Fe, Pb, Cr, TBC, TCC and E-coli. The results showed that mean values of harvested rainwater from all sampled rooftops are acidic especially at the onset of the raining season. TSS and TDS were highest in samples collected from Asbestos rooftop, followed by Aluminum rooftop while samples from galvanized Iron had the least irrespective of the rainfall event. Rainwater samples collected at the onset of rain had higher Ca2+ concentration than those collected at the peak of rain for all roof type with galvanized Iron rooftop catchment recording the highest concentration. Samples collected at the onset of the rain for all roof type had Fe concentrations above the WHO limit of 0.1mg/l while those collected at the peak of rain had lesser values. Values of pb, Cr were within WHO permissible limit. Analysis of microbial parameters revealed that samples collected from all rooftop and for both seasons exceeded WHO limit of <100cfu/ml for TBC. Rainwater samples collected from corrugated Asbestos rooftop had the highest bacterial load for both onset and peak of rain, followed by samples collected from Aluminum rooftop for the onset on rain. E-coli count was highest in water sample collected from corrugated Asbestos rooftop for onset and peak of rain. The Analysis of variance (ANOVA) shows that quality of rainwater harvested from galvanized Iron, Aluminum and Asbestos rooftop catchments does not significantly differ at 0.05 statistical thresholds among rooftop catchment although samples from asbestos rooftop catchment recorded highest contamination level. In view of the physicochemical and bacteriological results, harvested rainwater can be put to all forms of domestic use except for direct ingestion unless treated.Keyword: Rainwater harvesting, drinking-water, physicochemical, bacteriological parameters, Heavy metals, rainfall onset, rainfall pea

Influence of Effluent Discharge and Runoffs into Ikpoba River on its Water Quality

Unfettered effluent discharge, in addition to seasonal runoffs, into Ikpoba River, have been blamed for the ever poor water quality noticed in the river. This study seeks to investigate the role of industrialization and/ or urbanization on the degraded water quality of the river. Chemical analyses of samples of the river water collected at predetermined sampling points were undertaken and the observations obtained were subjected to ANOVA, correlation, and eigenvalue analysis. Results obtained showed that each point source has its relative contribution to the overall degradation of the river water quality. In merit order, the eigenvalue analyses carried out suggests that phosphate, nitrate, cadmium, copper, iron, lead and turbidity are the most offensive factors showing values of 0.868, 0.933, 0.770, 0.503, 5.063, 0.717, 30mg/L respectively. Remarkably, surface runoffs from municipal drains channelled to stations 1 and 2 contribute significantly to the turbidity with 4.333 and 4.233mg/L respectively, whereupon urbanization and industrialization are seemingly the culprits

Toxicity of Neatex (industrial detergent) and Norust CR 486 (corrosion inhibitors) to earthworms (Aporrectodea longa) in naturally spiked soil

Ecological effects of indiscriminate disposal of industrial chemicals into soils of the Niger Delta environment of Nigeria were assessed using earthworms in spiked natural soil in the laboratory. Populations of indigenous epigeic adult earthworms, Aporrectodea longa, were exposed to varying concentrations of two chemicals (industrial detergent and corrosion inhibitor) in natural soil to determine the acute toxicity of the chemicals. Earthworm acute toxicity test (OECD) 207 method was employed. After two weeks of earthworm exposure to Neatex and Norust CR 486 concentrations of 62.5, 125, 250 and 500 mg/kg, percentage mortality was measured as the ecological endpoint in the earthworms. Based on OECD 2003 guidelines, the chemically spiked soil rating showed that bothchemicals were slightly toxic. The estimated LC50 concentrations showed that Norust CR 486 (corrosion inhibitor) was more toxic than Neatex (detergent) at p < 0.05, t = 8.213. Earthworm mean mortality in both chemicals increased with increasing concentrations and exposure duration. Mean mortality observed in Neatex and Norust CR 486 were significantly different from the negative control suggesting that mortality may be attributed to the effect of the chemicals. The results obtained aretherefore indications of early warning signs of future soil deteriorations occasioned by indiscriminate disposal of these chemicals in the Niger Delta environment. This calls for regular monitoring and sustainable effluent disposal management