矿山污染区锌在土壤-油菜作物系统中的分布特征

Characteristics of Zinc Distribution in Soil-rape System in the Vicinity of Tongling Mining Area, China

通过系统采集土壤和油菜作物样品,研究了铜陵矿集区土壤锌含量的分布特征,影响土壤锌生物有效性的因素,油菜不同部位锌的富集规律。结果表明,由于成岩成矿活动导致成土母质中锌的富集,铜陵矿区周围耕作土壤锌含量普遍较高。矿业开发活动进一步加剧了土壤锌污染,其中污染程度最重的是矿区残坡积母质上发育的旱作土壤,其次为矿区下游引用污水灌溉的水稻土。土壤有效锌含量主要取决于全量锌的含量,其他影响因素主要是pH和有机质含量。土壤锌的DTPA提取率与土壤pH呈负相关,与有机质含量呈正相关。油菜籽实中锌的含量显著高于秸秆,二者平均含量分别为44.8mg·kg^(-1)和24.2mg·kg^(-1)。且秸秆锌含量受土壤有效锌含量的控制比较明显,而籽实累积锌的效率随土壤锌含量升高而递减的趋势明显。在较高的有效锌水平(>20mg·kg^(-1))下,油菜籽实中的锌含量不再随有效锌含量升高而增加,甚至出现降低的趋势。因此,虽然研究区的土壤锌污染现象十分普遍,但并不致于导致油菜籽实中锌的过量富集。但锌污染对油菜作物生长和籽实产量的影响以及对于其他作物食品安全的影响,尚有待于进一步的研究。

The distribution features of soil zinc in Tongling mining areas, the factors affecting their biological availability, and zinc accumulation in different parts of rape crops were investigated. The result showed that soil zinc in arable soil around Tangling mining areas was generally high as a result of the enrichment of zinc in soils during the formation of rock and mineral. The amount of available zinc in soil depended largely on the amount of total zinc, the pH and organic matters in soil as well. The DTPA-extractable ratio of soil zinc was negatively corre- lated with the soil pH, but positively with the organic matters. The amount of zinc in rape seed was significantly higher than that in the rape stalk, and the average amount was 44.8 mg· kg^-1 and 24.2 mg· kg^-1, respectively. The amount of zinc in rape stalks was apparently affected by the amount of available zinc. The accumulated amount of zinc in soil seed was negatively correlated with the amount of zinc in soil. Zinc in rape seed did not rise with the amount of available zinc, and even decreased when the level of available zinc was comparatively high （〉20 mg·kg^-1）. Thus, zinc pollution in the soil around the research area was common, but over-accumulation of zinc in rape seed was not possible. Further study needed to be conducted concerning the impact of zinc pollution on the growth of rape, the output of its seed and other crop food safety.