Showing papers in "African Journal of Environmental Science and Technology in 2012"

Groundwater chemistry and quality of Nigeria: A status review

Abstract: The present work is a review on the quality characteristics of groundwater in Nigeria. The aim was to collate, synthesize and analyse hydrochemical data from available literature in order to evaluate the physical and chemical character, quality and determine the sources of ions. The review process covered four major groundwater sedimentary basins viz Benin, Benue, Niger Delta, Sokoto and the Crystalline Basement Complexes. The issue of saline groundwater in parts of Benue and Niger Delta Basins were given attention. In general, data show that on the average, TDS for the groundwater from the different basins was < 250 mg/l compared to the saline groundwater with average TDS as high as 15700 mg/l. The high salinity was attributed to dissolution of salts and seawater intrusion. Nitrate concentration on the average is high especially, for Sokoto Basin indicating anthropogenic pollution. Descriptive and multivariate statistics together with cross plots indicate that the major geologic controls on the groundwater chemistry are chloride dissolution, weathering (silicate and carbonate) and ion exchange. With respect to agricultural and irrigation purposes, the groundwater are excellent besides the water from the saline groundwater from Benue Basin and the coastal aquifers. Key words: Groundwater, chemistry, quality, Nigeri

Water hyacinth as a biosorbent: A review

Abstract: Water hyacinth (Eichhornia crassipes), has attracted significant attention as the world’s worst invasive aquatic plant due to its extremely rapid proliferation and congest growth, presenting serious challenges in navigation, irrigation, and power generation. Attempts to control the weed have proved to be costly with minimum results. However, the same plant has demonstrated an amazing ability to absorb and concentrate many toxic metals from aquatic environments. Consequently, research activity on utilization of the plant has been registered over the last few decades. This article reviews literature related to the utilization of E. crassipes in the biosorption and recovery of metals from aquatic environments. Availability in large quantities, high biosorption capacity, renewability and low cost determine the extent to which biosorbents can be adapted technologically. Sorption dynamics through classical and competitive models, effect of physical and chemical treatment, pH, temperature, initial metal concentration and biosorbent dose on metal removal by water hyacinth is discussed. Key words: Biosorption, heavy metals, precious metals, recovery, water hyacinth

Localizing the strategy for achieving rural water supply and sanitation in Nigeria

Abstract: Water is essential for sustenance of life and determines the overall socio- economic development of any nation. In Nigeria, so many programmes to improve water supply and sanitation situation had been put in place by different administrations. Despite this, the hope of meeting the UN Millennium Development Goals (MDGs) target of safe water supply by the year 2015 is still uncertain. The MDG in water supply and sanitation aims to half the proportion of people without access to potable water supply and basic sanitation. More recent statements of the MDGs refer to the right of communities to have access to an adequate supply of safe water. Safe rural water supply coverage in this context is taken to mean water that does not represent a significant health risk; that is of sufficient quantity to meet all domestic needs; that is available continuously to all of the people and is affordable. There is no gainsaying the fact that the objective of improved rural water supply generally is limited to improved health. This paper therefore examines the extent to which government, implementors, and users are adopting different but interrelated mechanisms to deal with water stress in Nigeria. The paper also identifies the challenges in governance, government policies and priorities as responsible for poor service delivery. More importantly, a policy/institutional framework for sustainable rural water supply and sanitation delivery is developed towards achieving the Millennium Development Goals. Keywords : Rural water supply, sanitation, sustainable development, Millennium Development Goals, Nigeria

Correlation-regression model for physico-chemical quality of groundwater in the South Indian city of Gulbarga

Abstract: Groundwater is a major source of municipal and private water supply in Gulbarga city Water samples were collected from spatially referenced bore wells located in various wards of the city 150 bore well water samples were analyzed for electrical conductivity (EC), pH, total dissolved solids (TDS), total hardness (TH), Ca2+, Mg2+, Na+, K+, HCO3-, CO32- ClE‰, SO42-,NO3E‰, F and Fe All tests were performed as per standard methods and water quality was compared for both Indian and WHO drinking water standards Significantly positive correlation at 1 and 5% was found between many parameters EC prediction with multiple R2 value of 0999 indicated that 999% variability in observed EC could be ascribed to ClE‰ (76%), HCO3E‰(125%), NO3- (103%) and SO42- (11%) Multiple regression models can predict EC at 5% level of significance Nitrate, chlorides, TDS and fluoride concentration exceed permissible level of drinking water in 75, 41, 95 and 333% of the samples respectively It is recommended to treat groundwater prior to domestic use Key words: Groundwater, water quality, bore well, water supply, correlation, regression

Removal of heavy metals from aqueous media using native cassava starch hydrogel

Abstract: Graft copolymers of cassava starch and acrylonitrile were synthesized in aqueous solution using ceric ammonium ion as the initiator Saponification of grafted copolymer was done by reaction with sodium hydroxide and precipitated with methanol Grafting was confirmed byFourier transform infrared spectroscopy (FTIR) The grafted copolymer and the hydrolyzed graft copolymer (hydrogel) were used as sorbent for the uptake of heavy metals from the aqueous media The sorption capacity was evaluated by measuring the extent of sorption of nickel, copper, and leads metals ions, under equilibrium conditions Using the sorption isotherm models, the Freundlich model was found suitable because of good fitness and equilibrium data yielded the following ultimate capacity values for the sorbent of the grafted copolymer: 54 mgPb/g, 645 mgCu/g and 711 mgNi/g and for the hydrogel: 72 mgPb/g, 766 mgCu/g and 865 mgNi/g Hydrolysis increases the sorption affinity of grafted copolymer toward metal ions Acid stripping with 2% HCl resulted in 996% metal recovery for the hydrogel and 522% for the grafted copolymer This shows the ability of the product to be reused, upon drying between treatments Key words: Acrylonitrile, cassava starch, grafted copolymer, heavy metals, hydrogel, sorption

Food security and health in the southern highlands of Tanzania: A multidisciplinary approach to evaluate the impact of climate change and other stress factors

Abstract: Tanzania like many African countries is highly vulnerable to global environmental change, particularly climate change. The impacts of particular concern are related to food production, human health and water resources. Agricultural production, which is essential to ensure food security, is weather-dependent, which has occasionally subjected the country to food shortage and insecurity in years with low rainfall. Food security varies spatially and temporally depending on rainfall patterns and other multiple stress factors such as soil conditions, types of crops grown, socio-economic and cultural factors. The southern highlands of Tanzania which are the grain basket for the country are highly vulnerable to impacts of global change, especially decrease in the amounts of rainfall. In some parts, extreme events (for example, floods) have destroyed infrastructure hence affecting food distribution and access by the affected communities. Environmental change has also impacted on human health in various parts of Tanzania. The rise in mean temperatures is an important factor for increased incidences of malaria in the highlands that were traditionally free from malaria. Long-term climate records for the southern highlands of Tanzania confirm that the climate of the region is changing. Temperatures have steadily increased over the last forty to fifty years, and are closely associated with increasing prevalence of malaria and other health risks as confirmed by existing hospital records. Key words: Food security, human health, climate change, environmental change, multiple stress factors, southern highlands of Tanzania, multidisciplinary approaches

A survey on the effects of air pollution on diseases of the people of Rivers State, Nigeria

Abstract: The effect of air pollution on diseases of the people of Rivers State, Nigeria has been studied by analyzing epidemiological data collected from the State Ministry of Health, Nigeria in relation to ambient Air Quality data of the State and National Ambient Air Quality Standard data. It was found that a total number of 30,435 disease cases were reported during 2003 to 2008, out of which 61 patients died. The diseases found to be prevalent in the study area as a result of air pollution were pertussis, pulmonary tuberculosis, cerebrospinal meningitis (CSM), pneumonia, measles, chronic bronchitis, and upper respiratory tract infection (URT). The ambient air quality observed in the state (lead = 0.1115 ppm/year, particulates = 10 ppm/year, N-oxides = 2.55 ppm/year, SO2 = 1 ppm/year, VOC = 82.78 ppm/year) was far worse than the World Health Organization Air Quality Standard (Lead = 1 × 10-6 ppm/year, particulates = 105 ppm/year). This clearly indicates their unsafe levels and concomitant health risks. This study (survey on diseases) showed that air pollution has direct impact on health of the people. The intensification of environmental education, especially among rural dwellers in the state is very essential to overcoming the health as well as pollution problems. Key words: Air pollution, air quality standard, environmental education, epidemiological data, health effects, Niger-Delta, rural dwellers, World Health Organization

Phytoplankton diversity and abundance in Ndop wetland plain, Cameroon

Abstract: Phytoplankton is very sensitive to nutrient changes. Very little work has been carried out on the effect of these changes on the phytoplankton community in the Ndop wetland. Four paddy-field sites were studied to evaluate the effect of some abiotic factors on their occurrence and abundance of phytoplankton. Water samples were collected from the paddy-fields sites following age gradient 34, 32, 22 and 5 years old fields. Potassium, sodium, nitrate-nitrogen, phosphate-phosphorus, conductivity and pH were the factors that contributed to phytoplankton diversity and density. There was a positive significant correlation between pH and potassium (r = 0.99, P ≤ 0.01), and pH and sodium (r = 0.977, P ≤ 0.05). A negative correlation (r = -0.992, P ≤ 0.01) was observed between pH and evenness. Eight divisions of phytoplankton were recorded: Chlorophyta (26.42%), Bacillariophyta (20.76%), Pyrrhophyta (20.76%), Cyanophyta (15.09%), Chrysophyta (1.87%), Xanthophyta (3.77%), Rhodophyta (1.87%), and Euglenophyta (7.55%). The most abundant species included Microcystis aeruginosa, Anacystis sp., Chlorococcus disperses and Peridinum sp. These may be used as bioindicator of the water quality. Diversity index increased with increase in the age of paddy-fields sites. 43% of the species indicated eutrophic status, 16.9% mesotrophic, and 20.8% oligotrophic. Eutrophic species were more in the older paddy sites while the young paddy sites had more oligotrophic species. Key words : Phytoplankton, diversity, abundance, pollution, Ndop wetland.

Fluoride removal from water by zirconium (IV) doped chitosan bio-composite

Abstract: Water containing fluoride above 1.5 mg/L leads to health and environmental harms that creates skeletal and dental fluorosis. Adsorption technique prominently removes fluoride from water and its competence is reliant on development of recyclable, environmentally benign adsorbents. Many reported sorbents for defluoridation below stringent level 1.5 mg/L, displayed low to moderate adsorption capacity at varied concentrations and pH. Besides, viable defluoridation techniques are usually unsuccessful in developing countries. In this novel, cheap and efficient porous chelating resin, chitosan doped 20% zirconium (IV) with control morphologies were synthesized for delfuoridation. This bio-composite was at par with commercial alumina to mitigate water fluoride limit up to 1 to 1.5 mg/L. Effect of parameters namely pH, adsorbent dose, contact time and initial fluoride concentration were studied in batch scale. Kinetic data showed a rapid adsorption, indicated practicable operations in packed column. Findings encourage blending with other polymers as an effective option for defluoridation on a large scale. Key words: Fluorosis, chitosan, zirconium, bio-composite, defluoridation, water

Isolation of biosurfactant-producing marine bacteria

Abstract: Biosurfactant-producing marine bacteria were isolated from oil-spilled seawater collected from harbors and docks in Mumbai, India. Haemolytic activity, emulsification activity toward n-hexadecane, emulsion of mixtures of oils, drop collapsing test as well as oil displacement test were used to determine biosurfactant producing activity of marine bacteria. Among 25 strains, 20 different strains showed biosurfactant activity in which only 6 strains had haemolytic activity and were able to emulsify mixtures of oils (kerosene + petrol + diesel) in Marine Broth 2216 during cultivation. Six strains named MW1, JN1, MS3, JN2, MS1, and MW2 were identified by various identification tests. MW2 ( Pseudomonas sp.) Strain showed the highest emulsification activity against n-hexadecane. In addition, MW2 showed the highest activity for oil displacement test (3.14 ± 0.02) and emulsification test (70.5 ± 0.55) towards nhexadecane.

Determination of selected heavy metals in inland fresh water of lower River Niger drainage in North Central Nigeria

Abstract: The concentrations of some ferruginous ore associated heavy metals were determined in freshwater from River Niger. Water samples were collected from both upstream and downstream along the mainstream drainage channel, traversing past the steel production industry Ajaokuta between 2003 and 2005. The water samples were digested according to standard methods and tested for Cadmium (Cd), Manganese (Mn), Chromium (Cr), Nickel (Ni), Cupper (Cu), Zinc (Zn) and Lead (Pb) using Unicam 969 atomic absorption spectrophotometer. The mean concentrations (mg/L) of heavy metals were: Mn, 3.85 ± 0.93; Zn, 2.72 ± 0.57; Cu, 2.17 ± 0.73; Cr, 2.08 ± 1.27; Ni, 0.78 ± 0.12; Cd, 0.05 ± 0.02; Pb, 0.03 ± 0.02. The concentration of Mn, 1.74 to 8.37 mg/L; Cu, 0.58 to 4.50 mg/L; Cd, 0.02 to 0.13 mg/L were variable and inundating. The variations in heavy metal levels between sampling stations were not significant (P >0.05) with relative standard deviation from 2% for Cd and Pb to 12.7% for Cr. The order of dispersion (2 to 14%) showed that the measured metals are nearly homogenously distributed in the water with Cr, Mn, Cu and Zn having the highest concentration variations in the water samples. The concentrations of the evaluated heavy metals were within the guideline levels for freshwaters, and did not appear to have significant negative impact on the water quality. Key words : Heavy metals, freshwater, concentrations, quality, variation, distribution.

Fuel properties of loofah (Luffa cylindrica L.) biofuel blended with diesel

Abstract: Fuel properties of loofah oil and its ethyl ester blended with diesel were experimentally determined Biodiesel blends (10, 20, 30, 40, 50, 60, 70, 80, 90 and 100%) of loofah oil and its ethyl ester by volume with diesel was used The fuel properties of the biodiesel blends were determined according to American Society for Testing and Materials (ASTM) standards Pure Automotive Gas Oil (AGO) was used as a reference fuel The viscosity in the blends of loofah oil and its ethyl ester with AGO from B10 to B100 ranged from 45 - 431 mm2/s It was observed that the viscosities of 10 - 40% loofah ester-diesel blends fell within limit specified by ASTM standards The cloud points, the pour points and the flash points increased as the percentage of loofah oil and its ethyl ester increased in the blends The specific gravity of all the loofah biodiesel blends ranged from 0863 - 089 and fell within limit specified by international standards The heating values of the loofah biodiesel blends decreased from 4255 - 2875 MJ/L All the loofah biodiesel blends had sulphur contents ranging from 916 - 132% and lower than that of reference AGO The ash content of all the biodiesel samples produced from loofah oil ranged from 001 - 002% and were lower compared to AGO obtained as 012 The blends of loofah ethyl ester (LEE) of B10 and B20 were found to have acceptable fuel properties to power compression ignition engines Key words: Loofah ethyl esters, biodiesel, compression ignition engine, automotive gas oil (AGO)

An economic valuation of the Kakum National Park: An individual travel cost approach

Abstract: A major problem confronting environmental economists is the difficulty in valuing environmental resources and other public goods such as recreational sites since there are no markets or markets are imperfect in situations where they exist. The Kakum National Park, officially opened in 1994, is one of the most important parks in Ghana that protects a vast rainforest including its bio-diversity, habitats and natural processes, and houses the only Canopy Walkway in Africa which allows visitors to explore a tropical rainforest canopy from suspension bridges. Since the establishment of the Kakum National Park, not much has been done to assess its value to recreationers using the appropriate economic valuation techniques. This study seeks to address these questions by adopting the simple formulation of the individual travel cost method to derive the monetary value of Kakum National Park as well as factors that influence visits to the park using a survey of 246 visitors. Our results indicate that the annual per person value of the site is about 67.28 (US$ 46.40) which translates into an annual aggregate value of 8,481,653.20 (US$ 5,849,416) in 2009. Regression analysis using the zero-truncated negative binomial method indicate that travel cost, gender, knowledge of composite sites are the most important factors that influence visitation to the Park. Key words:

Removal of faecal bacteria and nutrients from domestic wastewater in a horizontal surface flow wetland vegetated with Echinochloa pyramidalis

Abstract: The aim of this study was to evaluate the removal of faecal bacteria and nutrients from domestic wastewater, in surface flow wetlands vegetated with Echinochloa pyramidalis. Horizontal surface flow (HSF) wetlands were fed with primarily treated domestic wastewater at organic loading rates varying from 20.74 to 27.15 g BOD/m2/day for two consecutive years. Water samples were collected at two weeks interval from the inflow and the outflow of the treatment wetlands for physicochemical and faecal bacteria analyses. Physicochemical parameters with highest removal rates were total suspended solids (TSS, 62-80%), Nitrates (57-73 %) and PO4-3 (57-84 %). Faecal indicators reductions of 1.4 and 0.3 log units (1st year) and 1.15 and 0.65 log units (2nd year) were respectively recorded in the vegetated and the control wetlands. Reductions of total coliforms, faecal coliforms and faecal streptococci were significantly higher in the vegetated wetland than in the non-vegetated control in both seasons of the first year. In the contrary, there was no significant difference in the removal rates of faecal indicators between vegetated wetland and the non-vegetated control during the dry season of the second year. Wetlands vegetated with E. pyramidalis was proven to be continuously efficient in the removal of faecal indicators for the two years of study, with no significant differences between the seasons of the year and between the years. Key words: Wastewater, wetlands, Echinochloa pyramidalis, faecal bacteria removal, nutrients removal

Assessing water quality of rural water supply schemes as a measure of service delivery sustainability: A case study of WondoGenet district, Southern Ethiopia

Abstract: This study was conducted in WondoGenet district, Southern Ethiopia to assess the water quality of rural water supply schemes in relation to the sustainability of their service delivery. 28 functional water points were selected randomly, for their assessments. The assessments included sanitary surveillance of water points and water quality analyses. Water samples were analyzed for pH, temperature, total dissolved solids, turbidity, total hardness, fecal and total coliform bacteria, fluoride, chloride, nitrate, manganese, and iron. The results obtained show that most of the 'user perceived' acceptable drinking water quality parameters were within the World Health Organization (WHO) guidelines for drinking water quality, based on aesthetic and taste considerations. Only one dug-well had marginally higher level of total hardness (that is, 220 mg/l of CaCO 3 ), while four water points had higher turbidity ranging from 8.3 to 64 NTU when compared with the WHO guidelines. In all the sampled water points, the level of iron (<0.009 to 1.25 mg/l), manganese (0.10 to 1.50 mg/l), chloride (0.80 to 62.5 mg/l), and nitrate (0.90 to 12.7 mg/l) were within the WHO guidelines. Fluoride was also found to be below the WHO health based limit (<1.5 mg/l). However, majority (85.7%) of the water points had detectable levels of total coliform bacteria (1 to 68 cfu). On the other hand, it was only in 25% of the water points that fecal coliform bacteria were detected (1 to 10 cfu). This shows that the bacteriological water quality is of concern as majority of the water points had detectable levels of coliform bacteria. Therefore, regular chlorination of water points, particularly dug wells, should continue. Besides, disinfection of water at the household level can be an added advantage. Key words : Ethiopia, quality, rural, supply, sustainability, water.

Effect of time of application of spent oil on the growth and performance of maize (Zea mays)

Abstract: The effect of spent oil pollution on the growth and performance of Zea mays at different stages of growth was investigated in this study. It involved addition of different quantities of spent oil to soils where Zea mays plants at different stages of growth were growing on. The plants showed differential response to quantities of spent oil added to the soils and the times of application. Plants exposed to spent oil pollution one week after germination had the highest level of growth inhibition and the highest chlorophyll content. The leaf area development of the plant was inhibited by the exposure of the plant to spent oil pollutionas observed seven weeks after germination. The application of spent oil to the soils three and five weeks, respectively after the germination of the seeds of Z. mays had similar effects on dry matter accumulation of the plant. Statistical differences occur on the growth and performance of the plants exposure to spent oil pollution at different stages of growth (p<0.05, p<0.01 and p<0.001). The results from this study showed that generally Z. maysmay suffer greater inhibition of growth and performed poorly when it is exposed to spent oil pollution at tender stage of growth. Key words: Spent oil, time application, growth, performance, Zea mays

Effect of stem - bark of Erythrophleum suaveolens (Guill. & Perri.) saponin on fresh water snail ( Lanistes lybicus ) tissues

Abstract: The study investigated the activity of saponin from ethanolic extract of Erythrophleum suaveolens stem bark against freshwater snail, Lanistes lybicus. The crude saponin (4 g) was separated by silica gel using gradient elution with dichloromethane in methanol (100:0 to 0:100) followed by thin layer chromatography using precoated silica gel 60 F254. Fractionated saponins (90:10, 80:20 and 70:30) were employed for snail toxicity using fresh water snails, L. lybicus. The biochemical changes were evaluated in haemolymph, muscle, intestine and hepatopancreas of fresh water snails exposed to sublethal dose of fractionated saponins. Elevation of activities of acid and alkaline phosphatase in the intestine and hepatopancreas, haemolymph and total protein level were observed. The activity of acetylcholinesterase was inhibited in the haemolymph, muscle, hepatopancreas and intestine of the snails. The activity of saponin was observed to be dose dependent as mortality increased with relative increase in the saponin concentrations. The study provides considerable scope in exploiting local indigenous plant resources for control of fresh water snails and monitor water pollution. Key words : Erythrophleum suaveolens, saponin, molluscicidal activity, Lanistes lybicus, pollution, hepatopancreas.

Observed urban heat island characteristics in Akure, Nigeria

Abstract: A climatological analysis of the differences in air temperature between rural and urban areas (ΔTu-r) corroborates the existence of an urban heat island (UHI) in Akure (7o 25’ N, 5o 20’ E), a tropical city in the south western part of Nigeria. The investigations which have been conducted out of a year-long experiment from fixed point observations focuses on the description of the climatology of urban canopy heat island in the Akure and the analysis of the results were presented. The results show that the nocturnal heat island was more frequent than the daytime heat island as it exists from less intense to higher intensity categories throughout the study period. Nocturnal heat Island intensity was observed to be stronger during the dry season. Although of lower intensity, daytime heat Island exists throughout the day except for few hours in the months of November and December that exhibits a reverse thermal contrast. The daytime heat island is observed to be intense in the wet months than the dry months, which may be caused by the evaporative cooling of wet surfaces. On the average, the urban/ rural thermal differences are positive, varying from 4°C at nocturnal hours during dry months to an approximate of 2°C around noon during wet months. This paper explain the aspects of heat islands and their relation to other causative agents such as the sky view factor (SVF) and also discusses its potential impact on energy demand. Key words: Urban heat island, sky view factor, energy demand

Potential impacts of climate change and variability on groundwater resources in Nigeria

Abstract: Climate change observed over the past decades has been consistently associated with modifications of components of the hydrological systems such as precipitation patterns, sea surface temperature, accelerated melting of glacier and ice caps, soil temperature and moisture, surface runoff and stream flow. Such changes are known to influence subsurface hydrological systems, which could lead to changes in groundwater recharge, discharge and storage of many aquifers. Although, there are uncertainties in the characterisation of climate change induced groundwater impacts due to largely multi-scale local and regional heterogeneity, there is need to evaluate groundwater resources, quality and vulnerability to climate change and variability. This paper attempts to assess the potential impacts of climate change and variability on groundwater resources availability and sustainability in Nigeria.

Assessment of physicochemical qualities, heavy metal concentrations and bacterial pathogens in Shanomi Creek in the Niger Delta, Nigeria

Abstract: The physicochemical and microbial qualities of Shanomi creeks in the Niger Delta of Nigeria were assessed between January and October 2011. The temperature across sampling stations ranged between 26 and 27.7°C, while pH varied from 7.49 to 8.74. Turbidity ranged from 176.62-189.96 NTU and conductivity varied between 360.45 and 454.88 µS/cm. The concentrations of other physicochemical parameters were as follows: BOD (6.39-7.64 mg/L) COD (84.25-97.27 mg/L); ammonia (26.83-33.98 mg/L); nitrate (37.25-43.89 mg/L); nitrite (37.35-41.75 mg/L); and phosphate (28.83-37.85 mg/L). The relative dominance of metals in the water followed the sequence: Al > Zn > Cu > Fe > Mn > Cd > Pb > Hg > As. Feacal and total coliform densities ranged from 1.05 × 102 to 4.25 × 103 (cfu/mL) and 1.56 × 102 to 6.40 × 104(cfu/mL) respectively. The study reveals that the water under study was heavily polluted and of serious threat to the aquatic biota and public health. Key words: Aquatic biota, contamination, pollution, public health, microbial indicators, toxic effects

Analysis of some meteorological parameters using artificial neural network method for Makurdi, Nigeria

Abstract: The mean daily data for sunshine hours, maximum temperature, cloud cover and relative humidity data, were used to estimate monthly average global solar irradiation on a horizontal surface for Makurdi, Nigeria. The study used artificial neural networks (ANN) for the estimation. Results showed good agreement between the predicted and measured values of global solar irradiation. A correlation coefficient of 0.9982 was obtained with a maximum percentage error (MPE) of 0.8512 and root mean square error (RMSE) of 0.0032. The comparison between the ANN and some existing empirical models showed the advantage of the ANN prediction model. Key words: Sunshine hours, relative humidity, maximum temperature, cloudiness index, global solar radiation

Combined uses of water-table fluctuation (WTF), chloride mass balance (CMB) and environmental isotopes methods to investigate groundwater recharge in the Thiaroye sandy aquifer (Dakar, Senegal)

Abstract: The quaternary sandy sediments which cover most part of the Cap Vert peninsula bear considerable groundwater resources. The aquifer lying beneath a densely populated suburb zone is encountered with major issues such as induced recharge from anthropogenic surface derived pollution and rising water table to ground surface. The present study was aimed at investigating the recharge in the unconfined aquifer of Thiaroye zone using both water table fluctuation (WTF), chloride mass balance (CMB) methods and environmental isotopes. Seasonal fluctuations of groundwater in response to precipitation are monitored during time period (2010 to 2011) using “Thalimede Orpheus mini” recorders in two piezometers (P3-1 and PSQ1) as well as long term record. Chemical and isotopic characterization of groundwater, rainfall and the unsaturated zone were also carried out using a network of 48 points consisting of 8 rainfall stations, 10 unsaturated zone profiles and 30 dug wells, boreholes and piezometers. The concentrations of chloride in rainwater are between 3.2 and 53.4 mg/L. These unsaturated zone profiles range from 65 and 572 mg/L. The recharge obtained by WTF method ranged between 18 and 144 mm during the rainy season (June to October), whereas the recharge given by CMB method ranged between 8.7 and 73 mm/year. The Thiaroye aquifer recharge obtained from these different methods also showed relatively similar range values. In this study, the WTF method applied computes both infiltration from rainwater and domestic waste water, while the CMB method estimates potential recharge from rainwater. Therefore, in the urban area, the CMB method cannot be applied due to the chloride input from waste water infiltration. Key words : Thiaroye basin, recharge, isotopes, chloride mass balance (CMB), quaternary sandy aquifer (Dakar).

Effects of rainwater harvesting and afforestation on soil properties and growth of Emblica officinalis while restoring degraded hills in western India

Abstract: Effect of rainwater harvesting (RWH) structures like Contour trench (CT), gradonie (GD), box trench (BT), V-ditch (VD) and afforestation with Emblica officinalis Gaertn (planted in August, 2005) were studied in 20% slopes with a view to improve soil status, plant growth, sequester carbon and rehabilitate hills for local benefits. Soil pH and EC decreased and percent soil, SOC, NO3-N and PO4-P increased in June 2010 over 2005. Enhanced soil water and nutrients in 20% and <10% slopes, respectively than in 10-20% slope, whereas it was 17.8, 16.1, 24.2 and 14.0% greater in CT, GD, BT and VD treatments, respectively over control. The highest plant growth was in CT plots in all slopes. Second best treatment was BT in <10% slope and VD in other slopes.Conclusively, RWH and afforestation facilitated soil improvement but CT/BT treatments were more efficient in conserving soil and water facilitating plant growth and helped restore the degraded hill. However, further research is required on soil water use and its partitioning in different vegetation component and the benefits accrued from it for the local people. Key words: Plant growth, hill restoration, soil carbon, soil nutrients, water dynamics

Predicting environmental factors influencing crop raiding by African elephants ( Loxodonta africana ) in the Luangwa Valley, eastern Zambia

Abstract: Elephant crop raiding is pervasive and widespread in elephant-agriculture landscapes. Due to rare investigations on underlying African elephant (Loxodonta africana) crop raiding processes and patterns, neither reliable predictive models nor empirical evidence on elephant crop raiding parameters are available or adequate to support intervening decisions by susceptible farmers and other stakeholders. By developing predictive models of binary logistic regression and employing questionnaire surveys, we examined the environmental factors influencing occurrence of crop raiding by interrogating effectiveness of counter-measures implemented by local farmers in Luangwa Valley, eastern Zambia. Farm sizes, vegetation types in peripherals of crop fields and types of counter-measures used by local farmers to restrain marauding elephants were the most important elephant crop raiding predictors. Smaller crop fields (≤4782.00 ± 342.00 m2) were more vulnerable than larger ones. Most crop fields (75.88%, n=236) surrounded by Brachystegia and Acacia dominated vegetation communities were damaged, largely due to high tree fruiting which were elephant attractants. Solar powered electric fences were more effective than other counter-measures. Though traditional methods were prevalent, they were less effective than other counter-measures. It was posited that additional capacity development of local farmers was required particularly, in participatory integrative land use practices to minimize elephant crop raiding. Key words: Predictive models, elephant crop raiding, conservation, Luangwa Valley, Zambia

Water supply arrangements in developing countries: A case study of Blantyre City, Malawi

Abstract: The provision of potable water in the cities of developing countries has been of concern for a long time. Most of the urban population, especially in unplanned settlements, relies on small-scale informal service providers. The challenge with such an arrangement, however, is that it has been associated with high charges, provision of poor quality water, unreliable and intermittent water supply, and a general deterioration of water infrastructure. Based on the literature and data on the institutions, organizations and demographics of Malawi, this paper argues that privatization of water supply in developing countries may not work for all income groups. However, there are other modes of delivery which if formalized and institutionalized may extend the coverage to the low-income neighbourhoods in a transparent and inclusive manner, and may be offered at affordable rates e.g. State-Civil Society, State-Informal Sector and the State-Civil Society-Informal Sector partnerships. This paper also argues that national authorities in Malawi need to spearhead public policies that will effectively regulate the operations of water service providers. Key words: water supply, unplanned settlements, institutions, privatization, developing countries

Toxicity assessment of treated effluents from a textile industry in Lagos, Nigeria

Abstract: Water pollution caused by industrial effluent discharges has become a worrisome phenomenon due to its impact on environmental health and safety. Textile industries contribute immensely to surface water deterioration and are categorized among the most polluting in all industrial sectors. For this reason, the toxicity of treated textile effluent was assessed in Celossia argentea by exposing them to effluent-polluted surface water from Ibeshe River. In the present study, parameters investigated includes, growth, photosynthetic pigment content, lipid peroxidation, and metal accumulation. The results showed that treated textile effluent from Nichemtex Company, affected the growth, dry biomass, root development and photosynthetic pigment content of C. argentea. The treated effluent caused 41% growth inhibition while the total chlorophyll decreased by 59.87% in relation to the control plants. Furthermore, it also elevated the levels of lipid peroxidation and heavy metals in the plant. It was therefore implicated that treated textile effluent entering Ibeshe River could cause toxic effects on organisms. It was emphasized that using the water for irrigation and as portable water in its present state is unsafe. Key words : Textile effluent, toxicity, surface waters, growth inhibition, Celosia argentea.

Assessment of toxic heavy metal loading in topsoil samples within the vicinity of a limestone quarry in South Western Nigeria

Abstract: Loading of Pb, Cd, Cr, Cu, Co, Mn, Ni, Zn, and Fe in topsoil samples (TS) collected from the vicinity of limestone quarry in South Western Nigeria was investigated. Thirty TS were sampled within ½ km radius from exploration area and 5 background samples from undeveloped area 10 km away from the study area. Limestone rock samples (RK) were also analyzed for metals’ content. All samples were pretreated and leached with appropriate acid solutions for some properties. All leachates were analyzed with atomic absorption spectrophotomer (AAS) technique. Soil pH ranged from 6.65 to 8.23, sand from 55.8 to 75.0%, silt from 16.6 to 34.6%, clay from 8.43 to 13.6%, and organic matter from 0.97 to 4.84%, respectively. These properties compared with those of background samples. Rock samples (RK) showed high Fe and Mn enrichment. Metals levels (mg/kg) in TS with background levels in parenthesis ranged as follows: 11.5 to 27.7 (10.5) Pb, 0.28 to 3.18 (0.55) Cd, 12.1 to 17.4 (5.50) Cr, 80.6 to 55.8 (3.81) Cu, 8.93 to 23.5 (11.1) Co, 262 to 710 (637) Mn, 6.34 to 17.4 (6.10) Ni, 36.0 to 620 (24.4) Zn, and 6585 to 13440 (4563) Fe. The elevated enrichment suggests influence from exploration activities. Residual phase showed highest enrichment for all metals possibly, because of high sand content. Positive correlations were shown between all metals, except Mn and Cd that were negative. Geoaccumulation index rating showed <0 for Mn denoting uncontamination, while others ranged from 1 to 2 indicating moderate contamination.

Monitoring the levels of toxic air pollutants in the ambient air of Freetown, Sierra Leone

Abstract: The ambient air quality in Freetown, Sierra Leone was investigated for the first time for toxic air pollutants. We investigated the levels of polycyclic aromatic hydrocarbons (PAHs), suspended particulate matter (SPM) and carbon monoxide (CO) and considered the implication of air quality and health risks. Particulate samples for PM2.5 and PM2.5 to10fractions were collected from four sites, and analyzed by HPLC/FLD. SPM and CO were monitored by realtime monitors. The annual average concentrations of total PAHs for PM2.5and PM2.5 to10 fractions for the various sites were found to be 37.18 and 6.24 ng/m3. The average concentration of SPM was 216.3 count per min (cpm) and the 8-h average concentration of CO was 10 ppm. Higher concentrations of PM2.5 and PM2.5 to 10 PAHs were found in dry season compared with wet season. The annual carcinogenic potential of PAHs was high in PM2.5 fraction while the levels of SPM and CO were high enough to raise concern of health risks. The ambient air quality in Freetown was judged to be poor and in view of human exposure, large portion of urban residents are exposed to high levels of toxic air pollutants which is recognized to be a public health risk. Key words: Air pollution, polycyclic aromatic hydrocarbons, suspended particulate matter, carbon monoxide, African countries

Removal of hazardous dye Ponceau-S by using chitin: An organic bioadsorbent

Abstract: There are numbers of applications of chitin for the removal of basic dyes and other colored organics from industrial effluents. In present research article there is focus on the preparation of bioadsorbent chitin and its application for the removal Ponceau-S dye from the aqueous solution by using chitin as an organic bioadsorbent. Chitin was characterized by scanning electron microscopy (SEM). Different parameters have been studied such as initial dye concentration, pH, contact time and adsorbent dose etc. In experimental study it is seen that the higher percent removal of Ponceau-S dye at optimum pH 3.5. Kinetics and equilibrium studies were also carried out by using the chitin which fit for Freundlich and Langmuir isotherm and kinetic study follows second order mechanism. Key words : Chitin, Ponceau-S, organic bioadsorbent, colored organic, industrial effluents.

Ecofriendly application of cellulase and xylanase producing marine Streptomyces clavuligerus as enhancer in biogas production from waste

Abstract: The marine actinomycete strain MAC 9 was used for the production of cellulase and xylanase from wheat bran with inducers oats and soy meal as substrate. Out of 30 actinomycetes screened from sediments of Tiruchendhur coastal areas of Tamil Nadu, India only 8 strains showed both cellulase and xylanase activity. The marine actinomycete exhibited highest enzyme activity at alkaline pH 8-9 with temperature ranging from 40-55°C. The enzymes were used in pretreatment of rice and wheat straw waste for biogas production. More biogas production was observed in the agricultural waste with the pretreatment of cellulase, xylanase and the combination of enzymes. Key words: Biogas, cellulase, energy, marine actinomycete, solid state fermentation, thermophilic, wheat bran, xylanase.