Investigation of Heavy Metals Pollution of Farmland Soil in a Coastal Province

Objectives To detect the heavy metal contents of farmland soil in a coastal province, evaluate the pollution hazard, and assess their ecological risk.

Methods The contents of Cd, Pb, Cr, Ni, Cu, Zn and As in 380 farmland samples from 19 counties located in the east, north, west and middle area of the coastal province were determined by ICP-MS. According to "Environment Quality Standards for Soil" (GB 15618-1995), the evaluation was carried out by single pollution index and Nemerow index. And ecological risk was evaluated by Hakanson potential ecological risk index method.

Results For the samples of farmland soil of the coastal province, the average contents of Cd were higher in reference to the criteria of GB 15618-1995 Safety Grade 2. Using single pollution index method, the pollution degree of Cd in north area was higher than the other 3 parts of area (P=2.862). Middle (P_Cd=1.896), east (P_Cd=1.634) and west (P_Cd=1.056) areas were at the light pollution level of Cd. The farmland soil of middle, north, east and west areas were within the range of safety grade in terms of other six heavy metals. Valued by Nemerow index, middle and east areas were at light polluted levels, north area was moderate and west area was at the alert level of heavy metal pollution. As estimated by Nemerow index, the overall comprehensive pollution index was 1.31, which indicated the farmland of the coastal province was slightly polluted by heavy metals. The heavy metals in the east, north and middle areas were at the corresponding risk level by Hakanson potential ecological risk index method.The farmland soil from west areas was at the moderate level of potential ecological risk.

Conclusions The coastal province has been in light pollution by heavy metals, the administration should be strengthened to prevent the pollution.