Pollution And Adsorption Characteristics Of Heavy Metals In The Soils Of Different Function Areas Of Nanjing

The pollution and adsorption characteristics of heavy metals in the soils of different function areas of Nanjing were studied in this paper. The main results received are as follows:(l)There is a trend of soil heavy metal concentration in different function areas, the soil heavy metal concentration in industrialized area > urban area >landscape area > developing area. Whereas in different land use ways at the same area the trend is as follows: the soil heavy metal concentration in forest soil > meadow soil > farm soil. There are different distributions for different heavy metals in soil profile(2)The integrate pollution index (PN) of farm soil in industrialized area is great than 3, it is seriously polluted. There is smallest soil pollution index in developing areas. It can be known from soil single pollution index that the pollution of heavy metals in this district is characterized by Cu and Zn pollution.(3) There may be a same source of soil heavy metals pollution in urban area, but in other areas the heavy metals of the soil may come from different sources.(4) The total soil concentration of Zn or Cr is remarkably positively correlated with that of available concentration, and the total soil concentration of Pb is positively correlated with that of available concentration. There is no correlation between total soil concentration and available concentration of Cu. The total soil concentration of Cr is positively correlated with the soil pH value, organic matter, soil texture and cation exchange capacity, and Zn positively correlated with the soil pH value and cation exchange capacity, Cu positively correlated with the soil pH value, Pb positively correlated with the soil organic matter, soil texture and cation exchange capacity.(5) The static state adsorption quantity of Cu2+ and Cd2+ will increase when the concentration of Cu2+ and Cd2+ in equilibrium solution increased. The desorption quantity of Cu2+ and Cd2+ will increase when the adsorption quantity of Cu 2+and Cd 2+increased. The sequence of greatest adsorption quantity of Cu2+is farm soil >forest soil >meadow soil, whereas Cd 2+ is farm soil > meadow soil > forest soil. But the capability of Cd2+ and Cu2+ adsorption and the buffer capacity is forest soil > farm soil >meadow soil.(6) It is a quick reaction of Cu 2+ and Cd 2+ adsorption in all these three soils, most of heavy metal ions can be adsorbed in few minutes. Adsorption will arrive the equilibrium with the time.(7) The adsorption amount of Cu2+for one soil at the same pH is greater than that of Cd2+, and the adsorption rate of Cu 2+ is also greater than that of Cd 2+.(8) The adsorption of Cu 2+ or Cd 2+ will increase as the pH go up. The adsorption amount has not reached the biggest in the studying pH range. With the increase of organic acid concentration, the adsorption rate of Cd 2+ will also increase, whereas Cu 2+ adsorption increased first, then decreased.