长期不同施肥下我国3种典型土壤重金属的累积特征

Evolution of Heavy Metal Contents of Three Soils Under Long-term Fertilizations

采用现场采样及室内分析测试方法,观测了1989年开始的红壤、黑土和灰漠土17a不同施肥(不施肥、施用化肥、化肥与有机肥配施和单施有机肥)下重金属元素Cu、Cd、Zn、Pb和Cr含量随时间序列的变化,阐明长期施肥下3种土壤中重金属元素的累积变化过程和富集特征。结果表明,灰漠土各处理的重金属含量在17a间持平;红壤和黑土中Zn、Pb和Cr含量17a间没有显著变化,各个处理间也没有显著差异,但施用有机肥处理的Cu和Cd含量则显著增加,其快速增加期起始于试验开始的5～6a后。其中红壤Cu含量在1996年之后的3a中由41mg·kg-1左右快速增加到64mg·kg-1左右,之后在高浓度持平;Cd含量则在最近的10a中从0.20～0.30mg·kg-1直线上升到1.30～1.50mg·kg-1。黑土Cd在6a中快速增加了2.4倍和1.4倍,2000年后在高浓度基本持平。红壤的Cu和Cd、黑土的Zn和Cd之间存在极显著正相关关系,表明其可能来源一致。长期施用有机肥是红壤和黑土中重金属显著富集的重要原因,有机肥的质量对土壤重金属的累积起重要作用。

Contents of Cu,Zn,Pb,Cr and Cd were periodically measured during 1989—2006 under different fertilizations in the Red Soil,Black Soil and Grey Desert Soil. In general,all heavy metals showed little change during 17 years of experiment for all the treatments in the Grey Desert Soil. For the Red Soil and Black Soil,Zn,Pb and Cr contents showed little change under all the treatments,whereas Cu and Cd contents revealed a significant increase under manure treatments. For Red Soil,Cu content increased from 41 mg·kg^-1 to 64 mg·kg^-1 after 6 years of manure treatments and was 55-65 mg·kg^-1 during the last -7 years under NKPM and M treatments,but 27-47 mg·kg^-1 in the other treatments. Cd contents linearly increased from about 0.25 mg·kg^-1 to the maximum 1.48 mg·kg^-1 in the later 10 years under NPKM and M treatments,while the other treatments kept in 0.1-0.2 mg·kg^-1. In Black Soil,Cd content was 0.4-0.6 mg·kg^-1 under NPKM and 1.5MPKM treatments during the last 6 years,much higher than the other treatments of 0.07-0.27 mg·kg^-1. During 17 years different fertilizations,manure could be the most important sources of heavy metals in Red Soil and Black Soil. The quality of manure conduced to the enrichment of heavy metals in soil.