Dynamic monitoring and fuzzy comprehensive evaluation of water quality of Wei River in Yangling

【Objective】Monitoring and assessment of Wei River water quality were carried out to provide theoretical basis for reasonable use of water source and pollution preservation.【Method】Water samples were collected bimonthly at Wei River in Yangling area in 2010,and water qualities including chemical oxygen demand(CODCr,CODMn),biological oxygen demand(BOD5),ammonium,volatile phenol and oil compounds were determined.Meanwhile,the fuzzy comprehensive evaluation and weighted average method was used to assess the current status of surface water quality in this area.【Result】Among the 7 water quality indicators,CODCr,BOD5,CODMn and volatile phenol levels conformed to class Ⅲ water standard of environmental quality standard for surface water,while ammonium,total phosphorus and oil compounds exceeded the class Ⅲ water standard.Water quality in winter and spring(samples of November,January and March) was worse than that in summer and autumn(Samples of July and September).Pollution of ammonium and total phosphorus was seasonal variation;however,pollution of oil compounds was the most important pollution factor along the whole year,with an excess of national standard of 0.05 mg/L.【Conclusion】In conclusion,pollution treatment in this area should be concentrated on the elimination of persistent organic pollutants and the removal of nitrogen and phosphorus in waste water.