基于小波分析郁江、浔江(贵港段)水质特征研究

Water Quality Characteristics of Yujiang River and Xunjiang River(Guigang) based on Wavelet Analysis

利用db小波、Morlet小波、连续小波变换(CWT)对贵港市三个国控监测站水质指标日浓度序列进行分析。结果表明,CODMn、TP、TN年际变化趋势6-7月、10-1月浓度出现高值,各监测子站有空间差异(石嘴的CODMn浓度超标最严重、火电厂DO浓度不达标最多、武林渡口NH3-N和TP、TN超标次数最多);CODMn、NH3-N、TP小波方差图的主周期为340 d,并且有相同的次周期140 d, DO小波方差图的主周期为260 d;CODcr存在为1~2个月、5~7个月的共振周期,BOD5、CODMn以1~4个月周期为主,DO存在约1~3个月的共振周期,NH3-N以1~5个月周期为主。说明贵港市地表水水质主要受到农业生产周期性活动的富余氮、磷营养物和农药残留物等面源影响。

Analyze the daily concentration series of water quality indicators at three national control monitoring stations in Guigang City using db wavelet,Morlet wavelet,and continuous wavelet transform(CWT).The results showed that the interannual variation trend of COD Mn,TP,and TN showed high concentrations from June to July and from October to November,and there were spatial differences among the monitoring stations(the COD Mn concentration in Shizui exceeded the standard the most severely,the DO concentration in thermal power plants did not meet the standard the most,and the NH 3-N,TP,and TN exceeded the standard the most times at Wulin Ferry);The main period of the COD Mn,NH 3-N,and TP wavelet variance maps is 340 days,and they have the same sub period of 140 days,while the main period of the DO wavelet variance map is 260 days;COD cr has resonance periods of 1~2 months and 5~7 months,BOD 5 and COD Mn mainly have resonance periods of 1~4 months,DO has resonance periods of about 1~3 months,and NH 3-N mainly has resonance periods of 1~5 months.The surface water quality in Guigang City is mainly affected by non-point sources such as surplus nitrogen,phosphorus nutrients,and pesticide residues from agricultural production activities.