Effects of Some Land Use Practices On Water Physico-Chemical Parameters, Nutrient Loads and Heavy Metal Concentrations In Water and Sediments Along the Malta River

Abstract

ABSTRACT Riverine land uses are among factors that influence water quality. Fresh water quality is nerlining and coDseqnemtiy imparting on the ecological heab:h of the ecosystem. Within the Mara River Basin as a result of population increase over the years. deforestations has increased to create room for human settlement, agricultural activities, urbanization and industrial .development These.ac:tivities halre the potential to cause do line in water quality~ however the effects of these activities on water quality in the Mara River Basin is very uncertain. The purpose of this study was to assess how land Uses along the Mara River watershed impact on the water .quati1y parameters .aud heavy metals levels in the river sediments, and concentration registered compared with acceptable standards limits as set by the National Environment Management Authority-Kenya (NEMA) and the World Health Organization (WHO) using documented standard methods of ~ Wata J!nd satiment samples were colle.ct.ed in triplicates ar 8 different sites based on distinct land use practices along the Mara River. A spring within the Mau Forest-Ainabsabet spring was used as the control 1 site (C1 ),while a stream of water emanating from a furested laud and draining into the main river after the mine site was used as conlml2 to establish changes in water quality due to land use downstream the main river. The water pH, dissolved oxygen, electrical conductivity, water turbidity, water temperature all regsistered a signif.u:ao1 incrrase ftom the CODtroi s.it.e ar a amfidence limit of p "$ a05,other than the concentrations of dissolved oxygen and turbidity at site 10 ( Kirumi wetland). The landuses along the river did alter the concentration of these physichochemical parameters ,however they fell within acceptable standard limi!s ofbuth NEM.>\.and WHO. Other than ammonium nitrogen concentrations, all the nutrient concentration of silicates, nitrates, nitrites, soluble reactive phosphorous, total nitrogen and total phosphorous at Emarti site.Ngerende I,Ngerende 2, 0ldmaIa Bridge.,New M.ata bridge had .a significant maease from the CflDtml site-Ainahsahet spring. At site 10-Kirumi wetland, an the nutrients other than silicates concentrations exhibited a significant reduction from the control site, and all fell within acceptable standard limits of NEMA, 2006 and WHO.,. 2011 for surface domestic watc:r~ All the heavy metals; conc.entIation registered significant increases from the control site, with concentrations such as Lead 49.80 ± O.20llgll,Chromium 82.26 ± l.44Jlgll and Iron 41.00 ± lmg/l after the mine site-site 8, registering amcentratioD .above the WHO., 2008 standard limits fur SUl"13ce40mestic water of 10 Ilgll for Lead, 50 Jlg/I for Chromium and 0.3 mg/l for Iron. The results suggest that land uses along the Mara River are contributing to the nutrient and heavy metal loading of the river, .b.o'w'c:vcr most parnll'lCtJ.:TS other than exhibiting significant increase from the CODtml site are within acceptable standard limits for both NEMA 2006 and WHO 20ll. As long as the land uses along the Mara River are sustained at their current levels,they don't pose a risk ofpolluting Lake Victoria.. The wetland in K.in.unt aided in reduction uf most COBtamiBants and should be well protected and conserved to ensure that the Mara River does not become a future reservoir for polluting the Lake Vidoria watel:s..