珠江三角洲典型肝癌高发区土壤锰形态及其生态效应

通过对珠江三角洲典型肝癌高发区及低发区表层、深层土壤样品和作物样品的系统采集，分别对土壤中各化学形态Mn含量及其与土壤Mn全量、土壤理化性质、蔬菜Mn富集之间的相关关系进行研究.结果表明: 研究区土壤Mn主要来自成土母质，受人类活动影响很小，肝癌高发区土壤Mn平均含量为577.65 mg·kg^-1，显著低于肝癌低发区（718.04 mg·kg^-1）和全国土壤Mn平均含量（710 mg·kg^-1）；肝癌高发区土壤Mn以残渣态和铁锰态为主，水溶态和交换态等生物有效态含量较少，二者分配系数之和不超过4%，低发区土壤Mn形态分布也有相似的分布特征，但其绝对含量显著高于肝癌高发区.Mn全量负荷水平和pH对各形态Mn的含量有重要影响，尤其是铁锰结合态、腐植酸结合态、碳酸盐态和残渣态的含量与土壤Mn全量呈显著正相关；水溶态、有机态Mn与pH呈显著负相关.5类蔬菜中，肝癌高发区油麦菜和大白菜Mn含量及富集系数显著低于肝癌低发区，其它蔬菜品种无显著差异.Mn在蔬菜中的累积量与土壤中有效态Mn（水溶态Mn与离子交换态Mn之和）呈显著正相关，而与土壤Mn全量和其他形态均无显著相关性.

Chemical forms and ecological effect of soil Mn in liver cancer's high incidence area in Zhujiang River Delta, China

The samples of surface soil, deep soil, and vegetables were collected from the liver cancer's high- and low incidence areas in Zhujiang River Delta to study the relationships between soil Mn forms and vegetables' Mn enrichment. The results showed that the soil Mn in study area was mainly derived from parent materials, and rarely come from human activities. The average soil Mn content in liver cancer's high incidence area was 577.65 mg x kg(-1), being significantly lower than that of liver cancer's low incidence area (718.04 mg x kg(-1)) and whole country (710 mg x kg(-1)). The Mn forms in high incidence area were mainly of residual Mn and Fe-Mn oxide, and less of water soluble Mn and exchangeable Mn, with the sum of the latter two's distribution coefficients being not higher than 4%. In low incidence area, the distribution pattern of soil Mn forms was similar to that in high incidence area, but the absolute contents of the Mn forms were significantly higher. Soil total Mn and soil pH had significant effects on soil Mn forms. There existed significant positive correlations between soil total Mn and the Mn forms of Fe-Mn bound, humic acid bound, carbonate bound, and residual, and negative correlations between soil pH and soil water soluble and organic bound Mn forms. Among the test five kinds of vegetables, Youmai lettuce and Chinese cabbage in liver cancer' s high incidence area had a significantly lower Mn content than in low incidence area, while the other three had less difference. The Mn enrichment in test vegetables was positively correlated with to the content of soil available Mn (sum of water soluble Mn and exchangeable Mn), but had no correlations with the contents of soil total Mn and other Mn forms.