Assessment of Nutrient Concentration in Sokori River, Southwest Nigeria (original) (raw)
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Physicochemical parameters of Kuti stream, Abaji Area Council, Abuja were studied for twelve months (January-December, 2019). Water samples were collected from the study area monthly from four sampling points that were 500 m distance apart into a clean 2-litre transparent plastic container and screw capped between the hours of 06.00-10.00. Samples were preserved in ice and taken to the laboratory for analysis. Temperature, pH, electrical conductivity (EC) and total dissolved solids (TDS) were measured in-situ with portable HANNA meter (HI 70007 pH/EC/TDS/C), while chloride (Cl-), sodium (Na +), nitrate (NO 3-), phosphate (PO 4 3-), sulphate (SO 4 2-), magnesium (Mg 2+), potassium (K +), calcium (Ca 2+), dissolved oxygen (DO), alkalinity and turbidity were analyzed ex-situ using standard methods. Descriptive statistics revealed that all parameters were within permissible limits recommended by the World Health Organization (WHO) and FRN's national environmental (surface and underground water quality control) regulations except PO 4 3-and turbidity. Analysis of Variance showed that all parameters are significantly different (p˃0.05) except pH across sampled points, while paired sample t-test showed that there was a significant difference (p<0.05) of all parameters between seasons except pH and Na. The high concentration of PO 4 3-and turbidity observed may be linked to the influx of runoff from nearby farms and degree of anthropogenic activities that took place in the stream during the study. PO 4 3-combined with NO 3-to cause eutrophication, which lead to higher oxygen demand and subsequent death of aquatic organisms. To reduce the concentration of PO 4 3-, sustainable agriculture and healthy activities around the stream should be practiced.
The influence of land use on nutrient regime in a tropical stream
Pollution of inland waters by agricultural, industrial and municipal wastes is a global problem and a common phenomenon in developing countries. These anthropogenic activities within the landscape facilitate the transfer of nutrients into aquatic ecosystems, sometimes leading to eutrophication which has adverse effects on aquatic ecosystems. Deposition of nutrient-rich sediments washed into rivers and stream is common during rainy season in places where the riparian buffer zones have been destroyed. River Isiukhu watershed land use comprises sugar-cane farm, forested, peri-urban and mixed agriculture from upstream to downtream. The research employed stratified random sampling. Nitrate-nitrogen was determined through ultra-violet screening spectrophotometric method while phosphatephosphorus through ascorbic acid method. Data analyses were done using Statistical Analysis System, version 9.1. Land use had a significant effect of both nitrate-nitrogen (F=1372.25, p<0.05) and phosphate-phosphorus concentrations. Peri-urban and mixed agricultural land uses recorded higher concentrations of these two nutrients while the forest land use recorded the lowest. The study showed that the type of riparian land use land cover influences nutrient concentrations in a water body and is an important area to be focused on by watershed managers.