Physico-Chemical Quality of Lake Kyoga at Selected Landing Sites and Anthropogenic Activities

Abstract

Lake Kyoga, one of the great African lakes in Uganda is facing an increasing pressure from human activities yet there is limited information on water quality of the lake. Therefore this study determined selected physico-chemical parameters of Lake Kyoga at some landing sites (Kayei, Acholi inn, Waitumba, Masindi port) and anthropogenic activities (boat dock, waste site, garden, fishing). The parameters included temperature, pH, water flow rate, dissolved oxygen (DO), nitrite ( 2 NO − ) and phosphate (PO 4 -P). The American Public Health Association (APHA) and Water Watch Australia protocols, standard meters, Merck's rapid test kits and timing of a float were used to measure the parameters. The results showed that the mean temperature, pH, DO, 2 NO − and PO 4 -P significantly (p < 0.05) varied across the anthropogenic activities. On the other hand, only temperature, pH and flow rate varied significantly (p < 0.05) across the landing sites. Lake Kyoga water flow rates were the fastest at Masindi port (0.031 m/s) and the least in Waitumba (0.021 m/s) governed by river inflow and surface vegetation cover. The mean pH (6.73 -7.15) and DO (10.15 -13.50 mg/l) of the lake at all the study sites were within the Environmental Protection Agency (EPA) standard values of 5.5 -8.5 and ≥9.0 mg/l respectively. These mean pH and DO values reflect more or less neutral waters which are equally well saturated with oxygen at all the landing sites. However, areas close to the waste sites had the least oxygen levels (10.15 mg/l) followed by gardens (11.82 mg/l) while fishing areas were the most saturated with oxygen (13.50 mg/l). On the other hand, temperature (25.06˚C -25.76˚C) est in the waste sites (0.35 mg/l), followed by gardens (0.24 mg/l) and least in the fishing areas (0.12 mg/l). However, phosphates in the form of P 2 O 5 were higher than the EPA standard value (0.5 mg/l) at Kayei (0.55 mg/l) and Acholi inn (0.55 mg/l) landing sites as well as at waste sites (0.80 mg/l) and gardens (0.55 mg/l) pointing to high nutrient (phosphorus) input at these sites. The high concentrations of nitrites in Lake Kyoga at the investigated anthropogenic activities and landing sites plus phosphate amounts close to waste sites and gardens including Kayei and Acholi inn landing sites call for vigilance in protection of Lake Kyoga through optimized planning. Hence, National Environment Management Authority should ensure proper sewage management in Lake Kyoga catchment to avoid discharge of untreated sewage into the lake. The authority should also regulate waste dumping and cultivation around the lake so as to reduce nutrient (phosphorus) enrichment.

Proliferation of &lt;i&gt;Salvinia molesta&lt;/i&gt; at Lake Kyoga Landing Sites as a Result of Anthropogenic Influences

“…Acholi inn landing site had the overall highest mean coverage followed by Masindi port, Waitumba and finally Kayei ( Spearman's correlation of S. molesta coverage with selected physico-chemical parameters [38] showed significant positive correlation with PO 4 -P (r s = 0.27, p = 0.01, n = 96). This is supported by previous studies which established that growth rates of S. molesta increase with increase in nutrients (e.g.…”

“…According to Wanda et al [7], the brittle stolons of S. molesta are easily broken by the movement of boats. Ongom et al [38] also reported that mixing of Lake Kyoga water increases the oxygen circulation in the lake. S. molesta weed coverage was the least in the fishing areas ( Figure 3) associated with low nutrient (PO 4 -P) concentrations (Figure 4) and the low weed coverage also resulted into increased dissolved oxygen concentrations at the fishing areas.…”

“…These anthropogenic activities are practiced at all the landing sites in the Lake Kyoga basin. Therefore, in order to determine the extent of S. molesta coverage as influenced by the anthropogenic ac- [38].…”

“…The coverage of S. molesta was determined using the quadrat method [39] [40] and on-site measurements taken around the S. molesta mats in the study sites to determine the physico-chemical parameters that favour the multiplication of S. molesta or are compromised by its spread [38]. Field work was done in one sampling period starting from December, 2015 to January, 2016.…”

Nitrate, phosphate and boron content in wastewater for crop irrigation in Mezquital Valley, Hidalgo

“…In this case, the concentration of phosphorus in the water is, on average, of 4.66 mg L -1 . This value indicates the hypertrophic condition in which the water is found (Moreno-Franco et al, 2010); domestic and industrial wastewater are the main source of phosphorus, as well as agricultural drainage, and its main characteristic is that it is composed of detergents that derive from anthropogenic activity (Lizárraga-Mendiola et al, 2013;Ongom et al, 2017) (Ayers & Westcot, 1985); in this case, the excess concentration of phosphate may be due to agricultural, domestic and industrial discharge (Velázquez-Machuca et al, 2010).…”