Heavy metal soil pollution in the Qinhuai River riparian zone

Key words: 
• soil ecology /
• Qinhuai River /
• riparian zone /
• soil heavy metals /
• pollution analysis and assessment

Abstract: Qinhuai River is the main river in Nanjing City,the overall length is more than 100 km,having 16 prongs and 2 630 km2 river valley. This objective is to rebuild and protect ecological system of the Qinhuai River riparian zone,pollution levels of five heavy metals(Cd,Zn,Cu,Cr,and Pb) in a riparian zone along the Qinhuai River of Nanjing were analyzed with sample plot method. Five plots were set,including Dongping of Lishui City,Yinxiang and Chalukou of Jiangning District,Dajiaochang of Qinhuai District and Zhongheqiao of Nanjing City,and each plot fell into near-riparian zone(0-30 m near river) and far-riparian zone(5-10 m near river). Results indicated that soil heavy metals in the riparian zone manifested spatial heterogeneity. Soil heavy metal content of the near-riparian zone was much than the far-riparian zone,and for topsoil(0-10 cm in depth) it was much than the subsoil(10-20 cm in depth). In different plots soil heavy metal content was distinctive. Also,in the upper reaches,due to less human interaction,soil heavy metal content was less than the middle and lower reaches.Both Cd and Cr content of the soil in Yinxiang were much than the standard level(Pn > 3.0); so soil pollution was heavy. Soil from Chalukou had an intermediate degree of pollution(Pn > 2.0),and soil came from Daojiaochang was lightly polluted(Pn > 1.0). The pollution index ranking for these five heavy metals in the riparian zone was Cd > Zn > Cu > Cr > Pb. There were positive correlations between soil Cu with Cd(PPPPPPP<0.05).