赣江南昌段水化学特征及城区影响

为探究赣江南昌段水化学时空变化特征及南昌城区对赣江的影响，于2015年4月~2016年3月在赣江南昌段（赣江进入南昌城区前、城区中心及流经城区后的北支、中支和南支）进行月周期采样，分析水体中的化学离子（HCO-3、Cl-、SO2-4、NO-3、K+、Na+、Ca2+、Mg2+、NH+4），重金属元素（Cr、Mn、Fe、Ni、Cu、Cd、Sb、Pb）以及溶解性有机碳（DOC）、总磷（TP）的分布特征及影响因素。结果表明：1）赣江南昌段总体水质在地表水源地标准限值内，水化学类型为HCO3-Ca型水，HCO-3、Cl-、SO2-4、NO-3、K+、Na+、Ca2+、Mg2+、NH+4、Mn和DOC含量在不同月份间的变化主要受流量影响，Cr、Fe、Ni、Cu、Cd、Sb、Pb和TP受流量影响较小。（2） 赣江南昌段污染程度为：南支污染最重，北支次之，中支、城区中心和入城区前的污染程度相近。TP、Cr、Ni、Cu、Sb、Pb在南支显著偏高，Mn在北支显著偏高。（3）TP、Ni、Cu、Pb受南昌城区影响显著，经城区后含量增加；DOC、Cd经城区后含量减小，但流经城郊农业区后增加；HCO-3、Cl-、NO-3、SO2-4、Na+、K+、Ca2+、Mg2+、NH+4、Cr、Fe、Mn、Sb受南昌城区影响不显著。 关键词： 赣江；南昌城区；水化学；时空变化

Chemical Feature in the Nanchang Section of Ganjiang River and the Influence of Urban

This study aims to explore the spatio-temporal variations of water chemistry in Nanchang section of the Ganjiang River and the influence of Nanchang city on the chemical feature.Water samples were collected from April 2015 to March 2016 monthly at five sites in this section.The distribution pattern and its influencing factors of chemical ions(HCO3-,Cl-,SO42-,NO3-,K+,Na+,Ca2+,Mg2+ and NH4+),heavy metal elements(Cr,Mn,Fe,Ni,Cu,Cd,Sb and Pb),dissolved organic carbon(DOC) and total phosphorus(TP) were screened.The results showed that:1.The water quality of Nanchang section were within the standard limits for surface water sources and the chemical type of water was HCO3-Ca.The variations of HCO3-,Cl-,SO42-,NO3-,K+,Na+,Ca2+,Mg2+,NH4+,Mn and DOC concentration were significantly related to the flow,while variations of Cr,Fe,Ni,Cu,Cd,Sb,Pb and TP concentration were not significantly related to the flow.2.The pollution status of the Nanchang section was as the follows:The south branch had the highest pollution level,followed by the north branch,the middle branch,water area in the urban center and the upstream had similar lower pollution level.Concentrations of TP,Cr,Ni,Cu,Sb and Pb were significantly higher in the south branch than in the other area.Concentration of Mn was significantly higher in the north branch than in the other waterbodies.3.Concentrations of TP,Ni,Cu and Pb were significantly increased because of the influence of the urban area;concentrations of DOC and Cd were decreased as the river flowing through the urban area,then increased at the suburban agricultural area;the urban area of Nanchang did not significantly affect oncentrations of HCO3-,Cl-,NO3-,SO24-,Na+,K+,Mg2+,Ca2+,NH4+,Cr,Fe,Mn and Sb.