The Sokoto-Rima basin defines the natural and socioeconomic lifeblood of northwestern Nigeria. Its agrarian nature is an indication of significant dependence on the supply of ecosystem services from its various rivers, streams, and wetlands. However, nitrogen (N) and phosphorus (P) constitute a great portion of chemical fertilizers used to enhance crop yields and poor management of these portend great threats for water quality. The overarching objective of this study was to examine the extent of spatial variation of nutrient dynamics in the Sokoto-Rima basin between 1992 and 2015 using the nutrient delivery ratio (NDR) model of InVEST (Integrated Valuation of Ecosystem Service and Tradeoffs) software. Land use/landcover, precipitation, digital elevation, and biophysical variables were the principal datasets employed as model input. The result of the study showed that the surficial N load is almost 15-fold of P in the Sokoto-Rima basin. Over the period of study, cultivated areas and rivers were spatially detected as nutrient sources and sinks respectively. The subsurface nutrient load is dominated by P while the amount of N load is insignificant. The trend of nutrient export is linearly defined: with 0.87% and 1.7% increase in N and P export respectively during 1992-2015. N and P exports vary spatially with a north-south increase-decrease index. Critical length and threshold are highly sensitive to changes in the parameterization of the NDR model. Thus, synergistic cultivation practices such as agroforestry should be extended to existing crop cultivation complexes to curtail nutrient enrichment in the Sokoto-Rima basin and ensure environmental sustainability.

Background: COVID-19, the disease associated with the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is currently a global pandemic with several thousands of confirmed cases of infection and death. However, the death rate across affected countries shows variation deserving of critical evaluation. Methods: In this study, we evaluated differentials in COVID-19 confirmed cases of infection and associated deaths of selected countries in Sub-Sahara Africa (Nigeria and Ghana), South Africa, Europe (Italy, Spain, Sweden and UK) and USA. Data acquired for various standard databases on mutational shift of the SARS-CoV-2 virus based on geographical location, BCG vaccination policy, malaria endemicity, climatic conditions (temperature), differential healthcare approaches were evaluated over a period of 45 days from the date of reporting the index case. Results: The number of confirmed cases of infection and associated deaths in Sub-Sahara Africa were found to be very low compared to the very high values in Europe and USA over the same period. Recovery rate from COVID-19 is not correlated with the mutational attributes of the virus with the sequenced strain from Nigeria having no significant difference (p>0.05) from other geographical regions. Significantly higher (p<0.05) infection rate and mortality from COVID-19 were observed in countries (Europe and USA) without a current universal BCG vaccination policy compared to those with one (Sub-Sahara African countries). Countries with high malaria burden had significantly lower (p<0.05) cases of COVID-19 than those with low malaria burden. A strong negative correlation (−0.595) between mean annual temperature and COVID-19 infection and death was observed with 14.8% variances between temperature and COVID-19 occurrence among the countries. A clear distinction was observed in the COVID-19 disease management between the developed countries (Europe and USA) and Sub-Sahara Africa. Conclusions: The study established that the wide variation in the outcome of the COVID-19 disease burden in the selected countries are attributable largely to climatic condition (temperature) and differential healthcare approaches to management of the disease. We recommend consideration and mainstreaming of these findings for urgent intervention and management of COVID-19 across these continents.

Understanding the dynamics of water yield as relates to water balance is vital for the functioning of ecosystems as well as model-based computation of their respective ecosystem services. In dryland regions such as the Sokoto-Rima basin, this is of cogent importance for effective planning, and management of its scarce water resources. In this study, we assess the spatiotemporal dynamics of quick flow (QF), local recharge (LR), and baseflow (B) between 1992 and 2015 using the Seasonal Water Yield (SWY) model of InVEST (Integrated Valuation of Ecosystem Service and Tradeoffs) software. Pre-classified land cover, rainfall, satellite-derived evapotranspiration, digital surface topography, and HYSOGs 250m soil datasets were used as software data inputs. The result of the study showed that QF, LR, and B depict similar spatial distribution with peak values generated within water-bearing land cover areas particularly water bodies and wetlands. QF was highest in 2002 (1,293.6 mm) while there were reductions in the subsequent years – 2012 and 2015. Similar patterns were observed in LR and B with much lower values. The temporal trend for the 23-year period of the study showed that QF had an increasing rate of 85,331 mm while decreasing rates of 56,131 mm and 27,597 mm were detected for LR and B respectively. Three key parameters – alpha, beta, and gamma showed evidence of sensitivity to changes in values. These water balance transactions provided an opportunity to review the impact of the sensitivity of the land cover, climate, and hydrogeological factors on water resources management particularly freshwater accounting in the Sokoto-Rima basin of the northwestern part of Nigeria.