南京市农田灌溉沟渠底泥重金属污染评价

Evaluation of Heavy Metal Pollution in Irrigation Pith Sediment in Nanjing City

对南京周边地区直接灌溉农田的小型沟渠底泥重金属污染进行了分析和评价。南京周边地区灌溉水域底泥重金属污染物,Pb、Cd江南地区高于江北地区,最高值是背景值的5.76倍和2.22倍;As、Hg江北地区远高于江南地区,最高值是背景值的22.1倍和31.0倍。综合评价结果江北地区底泥重污染至极重污染率100%,江南地区只有15.4%,除工业污染和交通运输污染外,农药包装物的不合理处置很可能是江北地区灌溉沟渠As、Hg高度积累,综合污染严重的重要原因。

An evaluation of heavy metal pollution in irrigation pith sediment in Nanjing district was presented in this paper. It showed that content of Pb, Cd in pitch sediment in south of Yangtze River area was higher than that in north of Yangtze River area; the highest content of Pb, Cd in sediment was 5.76 times and 2.22 times of geology background level respectively; while content of As, Hg in sediment in north of Yangtze River area was much higher than that in south of Yangtze River area, the highest content of As, Hg in sediment was 22.1 times and 31.0 times of geology background level respectively. Evaluation results indicated that in north Yangtze River area, nearly all pitch sediments were seriously polluted, while in south area only 15.4% of pith sediments were seriously polluted. Besides industry and traffic pollution, discard of pesticide package may be an important factor attributive to the high accumulation of As, Hg in pitch sediment in north area.