Optimal sizing of roof gutters and hopper for rainwater harvesting.

Bernoulli's equation was applied to a section of hopper collector to determine the appropriate dimensions of the hopper for rainwater harvesting. Also, the hopper surface area (SFA) for a given volume was minimized by differentiating it in relation to the slant angle (SA). Combining the rational formula-Manning's equation and the best hydraulic section criteria-expressions were obtained for the optimum sizes of rectangular and circular gutters. Minimum hopper SFA for a given volume was found to occur at an optimum hopper SA of 35.282°. With the optimum conditions, design charts were produced for the hopper, circular, and rectangular roof gutters. The ratio of hopper larger radius to the smaller radius designated as (α) gave hopper dimensions with excessively wide upper radius for values of 0.1 ≤ α ≤ 0.2. Alpha (α) values of 0.8 and 0.9 gave values of R and Z which are almost too close to be distinguished. The valid range of α for hopper design was found to be 0.292 ≤ α ≤ 0.8. The study revealed that roof plan area has more effect on hopper dimensions than gutter slope. In addition, the case of excessive long gutters can be addressed by placing the hopper at the lateral epicenter of the eaves. In this regard, regions with abundant rainfall can solve water scarcity issues if proper design parameters of RWH components are considered in order to avoid waste of water through the overflow of water collection systems.

Fluoride contamination in groundwater sources in Southwestern Nigeria: Assessment using multivariate statistical approach and human health risk.

The present study investigated the ionic and fluoride concentrations in tap water and its associated health risk to local dwellers of Ogun State (Abeokuta south), Nigeria. 63 samples were collected from twenty-one different locations. Results obtained revealed the mean concentration of fluoride (F-) as 1.23 mg/L. Other water quality parameters such as total dissolved solids (TDS), electrical conductivity (EC), F-, Fe2+, and SO42- surpassed the WHO guidance for drinking water. Strong positive correlation was observed between F- and TDS; F- and pH; TDS and EC; TDS and Mg2+; TDS and SO42-; TDS and HCO3-; EC and HCO3-; EC and SO42-; Na+ and Cl-; SO42- and Cl-. In addition, Empirical Bayesian Kriging (EBK) model was employed to spatially distribute the concentration of the analyzed elements within the study region. The chronic daily dose (CDD) and hazard quotient (HQ) were also used to evaluate the health risk associated with F-, considering dermal and ingestion as pathways. The results revealed that the associated HQ for infants between the age range of 6-12months within about 91% of the study region surpassed the accepted HQ limit. However, the HQ for age categories 11-16years; >65years; 18-21years; 21years; 16-18years within 95.2%, 90.5%, 80.95% and 100% of the study location were less than 1. Conclusively, the HQ values obtained in this study should serve as a baseline information for water management authorities, policymakers and the society at large towards addressing these pollution issues.

Assessment of geospatial and hydrochemical interactions of groundwater quality, southwestern Nigeria.

Groundwater pollution resulting from anthropogenic activities and poor effluent management is on the rise in Nigeria. Hence, groundwater used for domestic purposes is questionable and therefore calls for scientific scrutiny. Investigation of hydrochemical interactions and quality of groundwater resource is essential in order to monitor and identify sources of water pollutants. As a result, groundwater samples were collected from 21 locations in Abeokuta South, Nigeria and analyzed for physicochemical parameters using standard methods. Results obtained were subjected to hydrochemical and geospatial analyses. Water quality parameters investigated exhibited wide variations from location to location. Fe2+, Mg2+, SO42-, Cl-, total hardness (TH), Mn, Na+, NO3-, SiO2, and alkalinity exhibited the highest levels of variation with coefficients of variation of 131.3, 92.8, 83.9, 76.7, 65.9, 64.3, 57.6, 57.2, 57.0, and 52.5, respectively. The average pH value was 6.76 with 71% of the water samples being slightly acidic. Na2+, Mg2+, Fe2+, and EC contents exhibited the most violation of drinking water standards with percent violations of 100, 52.4, 47.6, and 47.6%, respectively. Parameters, such as Mn, Ca2+, NO3-, and CO32-, were within the WHO guideline values for drinking water in all the samples. The highest level of significant correlation was found to exist between Na+ and Cl- (r = 0.84, α = 0.01). Six principal components, which explained 83.5% of the variation in water quality, were extracted with the first (34.1%) and second components (15.7%) representing the influence of mineral dissolution and anthropogenic practices, respectively, on the hydrochemistry of the area. Four hydrochemical clusters were identified with distinctly partitioned water quality. Further analysis revealed that 38, 29, 24, and 9% of the samples were the Na-K-HCO3, Na-K-Cl-SO4, Ca-Mg-HCO3, and Ca-Mg-Cl-SO4 types, respectively. Anthropogenic activities are increasing threat to groundwater quality in the study location and therefore call for urgent attention. There is also a need for routine monitoring of groundwater in Abeokuta.

Estimation of some trace metal pollutants in River Atuwara southwestern Nigeria and spatio-temporal human health risks assessment.

Over twenty thousand persons rely on water from Atuwara River for drinking and other domestic purposes, hence the need to ascertain the human health risk inherent in such practice. Seventy-two water samples were collected from River Atuwara during the dry and wet seasons of 2018, and the concentration of heavy metals (Pb, As, Ni, Cr, Zn, Cu, and Cd) were measured using ICP-OES. A newly developed human health risk assessment method, HHRISK code was used to estimate the health risks associated with consumption of water from Atuwara River. Results obtained revealed that the concentration of heavy metals in the river was as follows: Cd < Ni < Pb < Cr < Cu < As < Zn in the wet season and Cd < Pb < Ni < Cu < Cr < As < Zn during the dry season. Principal component analysis suggested that industrial effluents, agricultural activities and base-rock interaction are responsible for pollution of Atuwara River. The cumulative hazard index (HIcum) obtained was 678.0 ±â€¯36.8 (for adult) and 1392.0 ±â€¯132 (for child) for non-carcinogenic risks. A cumulative carcinogenic risk (CRcum) of 1.01E-1±5.26E-3 and 4.96E-2±5.05E-3 was obtained for adult and children respectively, suggesting that up to 1 in 10 adults and 1 in 20 children may suffer from cancer over their lifetime as a result of consumption and exposure to water from River Atuwara. These results highlight the fact that unavailability of safe drinking water in many parts of the world remains a real and persistent risk which must be tackled.

An integrated assessment of land-use change impact, seasonal variation of pollution indices and human health risk of selected toxic elements in sediments of River Atuwara, Nigeria.

River sediments contain environmental fingerprints that provide useful ecological information. However, the geochemistry of River Atuwara sediments has received less attention over the years. One hundred and twenty-six sediments from 21 locations were collected over a two-season period from River Atuwara, and a detailed investigation of the land use and land cover (LULC) change between 1990 and 2019, analysis of selected toxic and potentially toxic metal(oid)s (TPTM) (Cu, As, Cd, Pb, Ni, Cr, Zn, Fe, Co and Al) using ICP-OES, pollution index assessment, potential source identification (using center log-transformation approach), potential ecological, and human health risk assessment were conducted. The results of the LULC change revealed that the built-up area increased by 95.58 km2, at an average rate of 3.186 km2/year over the past 30 years. The mean concentration of metal(oid)s increased in the order of Cd < As < Cr < Pb < Co < Ni < Cu < Zn < Fe < Al, and Cd < As < Cr < Co < Pb < Ni < Cu < Zn < Fe < Al during the dry and wet seasons, respectively. Meanwhile, the statistical analysis of the data spectrum inferred possible contamination from lithological and anthropogenic sources. According to the pollution load index, 90.48% of the sediment samples are polluted by the metal(oid)s. Potential ecological risk assessment identified Ni, As, and Cd as problematic to the ecological community of River Atuwara. Regarding the metal-specific hazard quotient via ingestion route, the risks are in order of Co â‰« As â‰« Pb > Cr > Cd > Al > Ni > Cu > Zn > Fe for both seasons and the carcinogenic risk for children via ingestion route presented a value higher than the safe limits for As, Cd, Cr, and Ni during both seasons. This outcome highlights the need for prompt action towards the restoration of environmental quality for communities surrounding River Atuwara.