高氯低化学需氧量地表水分析方法研究

Research on the Analysis Methods of Surface Water with High Chlorine and Low Chemical Oxygen Demand

定边县部分河流断面水质的氯离子(Cl^(-))含量一般在2000~4000 mg/L之间,河(湖)床与两岸盐碱化严重。而氯离子是化学需氧量测定时的主要干扰物质,可通过选择不同浓度硫酸汞络合的方式消除氯离子对COD测定结果的干扰。当C(Cl^(-))≤2500 mg/L,使用10 mg/L硫酸汞溶液时,氯离子对COD结果干扰很小;当2500 mg/L≤C(Cl^(-))≤3500 mg/L,使用15 mg/L硫酸汞溶液时,氯离子对COD结果干扰小;当3500 mg/L≤C(Cl^(-))≤4000 mg/L,使用20 mg/L硫酸汞溶液时,氯离子对COD结果干扰小。

The chloride ion content in the water quality of some river sections in Dingbian County is generally from 2000 mg/L to 4000 mg/L,and the river(lake)bed and both banks are severely salinized.Chloride ions are main interfering substances in the determination of chemical oxygen demand,and the interference of chloride ions on COD determination results can be eliminated by the complexation of different concentrations of mercury sul-fate.When C(Cl^(-))≤2500 mg/L and using a 10 mg/L mercury sulfate solution,the interference of chloride ions on COD results is very small,when 2500 mg/L≤C(Cl^(-))≤3500 mg/L and using a 15 mg/L mercury sulfate solution,the interference of chloride ions on COD results is small,and when 3500 mg/L≤C(Cl^(-))≤4000 mg/L and using a 20 mg/L mercury sulfate solution,the interference of chloride ions on COD results is small.