武汉沿长江、汉江Cd高值带成因初探

Origin of cadmium high-value zones along the Yangtze River and Hanjiang River in Wuhan,Hubei,China

在1999—2000年第一轮多目标区域地球化学调查中,湖北省地质调查院在武汉市辖区的沿江(长江、汉江)冲积成因土壤中发现了重金属元素Cd的高值带,长江和汉江冲积土中Cd含量分别为0.33×10-6和0.27×10-6。研究结果表明:①长江和汉江冲积成因土壤的化学组成有明显的差异;②两江冲积物化学组成分别受扬子陆块和秦岭造山带表壳岩系化学组成的制约;③两构造单元表壳岩系相对富Cd岩石的风化产物是两江沿江冲积成因土壤Cd高值带的主要来源之一;④沿江冲积成因土壤中Cd的富集与其表生地球化学性质有关。

Cadmium high-value zones have been recognized in alluvial softs in the Yangtze River and the Han River valleys under the jurisdiction of Wuhan City during the first round of multi-target regional geochemical survey in 1999 to 2000. The Cd contents in the Yangtze River and the Han River alluvial soils are 0.33×10^-6 and 0.27×10^-6 respectively. Study showsthat：① the chemical compositions of the alluvial softs in the Yangtze River and Han River valleys are markedly different;② the chemical compositions of alluvial sediments of the two rivers are constrained by the chemical compositions of supracrustal rocks of the Yangtze block and Qinling orogenic belt respectively; ③ the weathering products of Cd-rich rocks in the supracrustal rocks of the two tectonic units are the main source of Cd in the alluvial softs of the two river valleys; and④Cd enrichment in the alluvial softs along the rivers is probably related to their supergene geochemical characteristics.