Abstract:

In this study, Alaşehir River Sub-basin was selected as a pilot area considering its population, developing industry and agricultural activities, and it was aimed to examine the effect of pollution from point and diffuse sources on surface water quality. Urban and industrial wastewaters coming to the receiving environment were considered as point source pollutants while fertilizer use, livestock activities, land use, solid waste leachate, septic tank use and atmospheric convection were considered as diffuse source pollutants. A rough and easily applicable methodology was presented for calculating nitrogen (total nitrogen, TN) and phosphorus (total phosphorus, TP) loads from these sources. For determining the impact of these pollution sources on surface water quality, main streams of the basin were monitored for four periods in 2015-2016. The obtained results were evaluated over the conventional parameters in Table 2 of Annex 5 of the Surface Water Quality Regulation (10.08.2016, RG: 29797). In the light of the results, a significant part of the total TN and TP load (79% of TN, 61% of TP) occurred in the basin came from activities with diffuse sources. The major sources of diffuse pollution were fertilizer use (37% of TN, 48% of TP) and livestock activities (34% of TN, 41% of TP). Point source pollution was mostly caused by urban wastewater discharges (93% of TN, 95% of TP and 83% of COD). The surface water quality was generally defined as highly polluted (Class IV) and polluted (Class III). In the presence of organic parameters, point source pollutants were found as responsible for pollution. The water quality of the streams passing through the areas with point and diffuse pollutant sources deteriorated significantly.

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