长江镇扬河段不同时期河漫滩沉积物磁化率及其环境污染指示意义

Magnetic susceptibility of river floodplain sediments at Zhenjiang-Yangzhou reach of the Yangtze River and its significance as environmental pollution indicator

为探讨河漫滩沉积物磁化率对环境污染的指示,采用重力浅钻法采集了长江下游镇江-扬州河段3个100 cm的河漫滩沉积岩芯,对岩芯沉积物进行质量磁化率和微量元素的测定。研究发现:老河漫滩沉积柱SY7的磁化率在12.11×10-8~30.60×10^-8 m^3/kg之间,平均值为20.79×10^-8 m^3/kg;现代河漫滩沉积柱SY5和Z2的磁化率明显较高,是老的江心洲河漫滩沉积物磁化率的5~6倍,SY5的平均值最高,为123.20×10^-8 m^3/kg。通过对研究区河漫滩沉积物重金属元素污染与长江流域水系沉积物背景值的对比研究发现,Cu、Ni、Cr的污染比较严重,新生成河漫滩明显比老河漫滩污染严重。简便、快速测定的磁化率分析可以作为河漫滩沉积物重金属污染诊断的重要手段之一。

In order to reveal the indicating significance of magnetic susceptibility of river floodplain sediments, the magnetic susceptibility has been determined by using 3 river floodplain sediment cores of 100 cm at the lower reaches of the Yangtze River between Zhenjiang and Yangzhou. It can be found that: the magnetic susceptibility of old river floodplain sediment core SY7 ranges from 12.11×10^-8 m^3/kg to 30.60×10^-8 m^3/kg, for the average in 20.79×10^-8 m^3/kg;the magnetic susceptibilities of SY5 and Z2 in the modern river floodplain sediments are obviously larger, the highest average value of SY5 is 123.20×10^-8 m^3/kg, and the modern river floodplain’s magnetic susceptibility is 5-6 times of old river floodplain sediments. Heavy metal pollution in the river floodplain sediments of the study area was compared with the background values of stream sediments in the Yangtze River basin, and the heavy metal pollution in Cu, Ni and Cr was more serious. Meanwhile, the pollution of newly formed river floodplain was more severe than that of old river floodplain. Simple and rapid determination of magnetic susceptibility can be used as one of important means for diagnosing heavy metal pollution in floodplain sediments.