Influence of agricultural drainage on the pollution of Imbang River, Negros Occidental [Philippines]
1999
Gonzales, G.A. (Philippines Univ. in the Visayas, Miag-ao, Iloilo (Philippines))
The concentrations of key pollutants carried by agricultural run-off from the drainage area of Imbang River, Negros Occidental were determined. The quantities loaded into the river were also estimated to assess the contribution of agriculture to the degradation of the river. Agricultural production in sugarcane and rice plantations in the area relied on chemicals to enhance production and control pests. Run-off from agricultural land contained, on the average, 0.196 ppm PO4-P, 0.1615 ppm NH3-, 0.0197 ppm NO2-N, and 1.6694 NO3-N from fertilizer inputs and other sources. The run-off was positive for various organochlorine pesticides though these were present within the acceptable limits. It also had some oxygen-demanding properties, with BOD [biological oxygen demand] averaging 7.4 ppm, and carried 465 ppm of total solids, 296 ppm of total suspended solids, and 0.40 ml/li of settleable solids. In general, run-off-transported loads of polluting nutrients, pesticide residues, sediment and waste particles are not presently economically or environmentally alarming. However, there are indications that levels of these materials on occassions exceed the maximum tolerable limits
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