Assessing the influence of horticultural farming on selected water quality parameters in Maumau stream, a tributary of Nairobi River, Kenya

Abstract

This study aimed to determine the levels of contamination in Maumau stream as a result of horticultural activities in its vicinity. The stream was purposefully delineated into three blocks including upstream, midstream and downstream, where water samples were collected and analyzed for physicochemical attributes. Standard analytical procedures for water analysis were followed in laboratory analysis and the collected data was analyzed using Genstat software. Analyzed parameters include total dissolved solids (TDS), salinity, total suspended solids (TSS), sulphates (SO 3 −3 ), phosphates (PO 3 −3 ), nitrates (NO 3 - ), fluoride (Fl − ), turbidity, chloride (Cl − ), magnesium (Mg +2 ), sodium (Na + ), potassium (K + ) and zinc (Zn +2 ). The results were presented in tables and a graph against WHO standards. All measured parameters showed significant differences (p=<0.001) among their means across the sampling sites and control. The pH did not show a clear trend from upstream through midstream to downstream. The concentrations of chloride decreased down the stream with control, midstream and downstream showing no statistical significance. Means of fluoride, magnesium, phosphates, sulphates, total soluble solids and zinc increased down the course of the stream. Increasing concentrations of the physicochemical parameters down the stream was attributed majorly to release and addition of agrochemicals to the stream from the nearby farms. A lucid knowledge of the nexus between land use and water quality was recommended as a prime management implication. In conclusion, the water quality of Maumau stream is being degraded by horticultural activities along the stream. Key policy actions including river pegging should be adopted to protect the water quality.

Implications of Dynamic Interactions between Meteorological Patterns and Surface Water Quality on Environmental Health&amp;#8212;A Case Study of the Nairobi River

“…This research highlights the complex interplay of pollution sources affecting water quality in the Nairobi River, including both urban and agricultural contributions. Wilson et al (2021) documented the impact of various sources of pollution on the Nairobi River. The study identified an area where wastewater from car wash operations joined the downstream, contributing to an increasing trend in water pollution along the stream course (Wilson, Michieka, & Mwendwa, 2021).…”

“…Wilson et al (2021) documented the impact of various sources of pollution on the Nairobi River. The study identified an area where wastewater from car wash operations joined the downstream, contributing to an increasing trend in water pollution along the stream course (Wilson, Michieka, & Mwendwa, 2021). The increasing turbidity downstream was indicative of rising concentrations of metallic elements, anions, and alluviation due to siltation from cultivated land.…”

“…As water temperature increases, conductivity also tends to rise, affecting the solubility of gases like oxygen and influencing chemical reactions (O'Donnell, 2022). Moreover, increasing water temperatures have been linked to changes in nutrient concentrations, with studies showing a decrease in dissolved oxygen concentration and an increase in ammonia, nitrate, total nitrogen, chemical oxygen demand (COD), and phosphate levels (Wilson, Michieka, & Mwendwa, 2021).…”