经济快速发展区土壤重金属累积评价

以经济快速发展典型区昆山市为研究区,结合重金属总量、有效态和形态3方面指标建立了昆山市土壤重金属累积评价的指标体系,并对其进行了综合评价.结果表明,昆山重金属总量累积指数空间变异较小,为42.57%,但重金属有效态和形态累积指数(特别是重金属活性形态)空间分异很大,分别达82.75%和77.83%.若以土壤剖面母质层各指标的含量为参比值,土壤重金属总量累积指数平均为1.01,为轻度累积水平,重金属有效态累积指数平均为2.46, 达中度累积水平,重金属形态累积主要表现为重金属活性形态的累积,形态累积指数平均达4.32, 达重度累积水平.重金属综合累积指数的平均值2.56, 达中度累积水平,变异系数达70.03%,有21.54%的面积土壤重金属达轻度累积,54.70%的面积达中度累积,23.76%的面积达重度累积.不同功能区土壤重金属的各项累积评价指数均以养殖区最低,冶金电镀区最高,但功能区间差异未达显著水平;不同土壤类型的各项累积指数均达显著水平,且均以乌栅土的累积指数最高,显著高于黄泥土和青泥土的累积指数.

Evaluation of Soil Heavy Metals Accumulation in the Fast Economy Development Region

Evaluation of soil heavy metals accumulation was studied in Kunshan City, a typical region of the fast economy development region in China. 126 soil samples were collected and analyzed, and evaluation indexes of soil heavy metal accumulation, which including total concentration of soil heavy metal index (THMI), soil available heavy metal index (AHMI) and fractionation of soil heavy metal index (FHMI), were established, and the heavy metal accumulation conditions of soil in this region were also discussed. Results showed as follows: the spatial variability of THMI was relative lower, with a mean value of 42.57%, whereas strong variability was found in AHMI and FHMI (especially active fraction of soil heavy metals), with the average value of 82.75% and 77.83%, respectively. Judging by each index reference standard of C Horizon, THMI was low-grade with a mean value of 1.01, while the AHMI and FHMI reached to medium accumulation and serious accumulation, with the average values of 2.46 and 4.32, respectively. The synthetic accumulation index of soil heavy metals (SHMI) was 2.56, reaching to medium grade level and with strong variability. 21.54% land area was in low-grade accumulation and 54.70% land area was in medium grade accumulation, while 23.76% land area was in serious accumulation under SHMI evaluation system. All the accumulation evaluation indexes in livestock breeding zone were the lowest, while the indexes in the smelting and plating zone were the highest, but the indexes difference between two zones were unobvious. There were markedly differences in soil types, which the accumulation indexes in Wushan soil were significantly higher than those in Huangni soil and Qingni soil.