我国菜园土壤中某些重金属元素的含量与分布

CONTENTS AND DISTRIBUTION OF SOME HEAVY METAL ELEMENTS IN THE VEGETABLE CULTIVATED SOILS IN CHINA

本文对我国各主要起源母土上发育的厚熟土、不同熟化程度的菜园土以及相对应的粮田土壤３７个剖面中某些重金属元素的全量及有效态含量进行了研究，结果表明：菜园土壤随种菜历史的延长、熟化程度的增加、重金属元素Ｚｎ、Ｃｕ、Ｐｂ的含量有明显增高的趋势。元素在剖面中的分布以表层含量最高，向下递减。厚熟土由于具有较厚的熟化表层，元素全量及有效态含量在０—４０ｃｍ土层中均较高，多在过渡层之下出现突然降低的转折；中度和轻度熟化的菜园土中，表层金属元素的含量低于厚熟土，但高于粮田土壤，剖面分布上多在表层之下则出现明显降低；粮田土壤中各金属元素含量则无显著的剖面变化。相关分析表明：Ｚｎ、Ｐｂ、Ｃｕ三种元素之间，以及全量与有效态含量均与有机质含量呈极显著的正相关，但与土壤的ｐＨ值和ＣａＣＯ３含量无相关性。与此含量之间均呈显著的正相关，并与速效Ｐ含量有显著的正相关。Ｚｎ、Ｐｂ、Ｃｕ的全量和有效态相反，全量Ｆｅ及有效Ｆｅ、Ｍｎ含量均与ｐＨ值和ＣａＣＯ３呈极显著的负相关，但与有机质含量则无相关性。因此，Ｆｅ、Ｍｎ两元素的含量与菜园土的熟化程度无关，而Ｚｎ、Ｐｂ、Ｃｕ三种元素则随菜园土的熟化显著增加，是菜园土壤中最普遍的污染元素。

The total and available contents of several heavy metal elements in thirty-seven Profiles of Fimus soils, different vegetable cultivated mellow soils and corresponding grain crop soils derived from different original soils in China were studied.The distribution characteristics of heavy metals,the relationships between total and available element contents, between elements and some soil properties,and among elements were elucidated. Results showed that as the ripening degree increased,there was an evident increase tendency of increase in the contents of Zn,Pb,Cu and Cd.Total and available metal element contents decreased with the soil depth.In Fimus soils,the elemental contents were higher in the upper horizon of 0 to 40 cm and decreased dramatically below the transitional horizons due to the thicker fimic epipedons.In the moderately and slightly ripening vegetable cultivated soils,element contents were higher only in the surface horizons and decreased sharply below surface horizons,but there were no evident changes in the profiles of grain crop soils.Correlation analyses indicated that there existed significant positive correlations among Zn, Pb and Cu,and between total and available contents of elements,available P and available elemental contents.There was no significant relationship between pH and CaCO3 on the one hand and Zn, Pb and Cu on the other.In contrast,total Fe and available Fe and Mn were found to bear significant negative correlations with pH and CaCO3 but no significant relationship existed between Fe and Mn contents and organic matter contents,suggesting that Fe and Mn contents had no retationship with the ripening processes.However, Zn,Pb and Cu contents increased with the ripening degree.Therefore, Zn,Pb and Cu could be considered as the main contaminant elements in vegetable cultivated mellow soils.