张新帅 钟伟 湛方栋 何永美 李博 李明锐 杨志新

摘 要：玉米（Zea mays L.）是云南鉛锌矿周边农田主要的夏季作物。通过大田试验，研究矿区周边农田种植的玉米根系低分子量有机酸含量、根际土壤镉铅形态及其镉铅累积特征。结果表明：（1）旺长期玉米根系分泌的主要是柠檬酸、草酸;成熟期玉米根系分泌主要是酒石酸和草酸，草酸分泌量较旺长期显著增加;（2）玉米根际土壤Cd化学形态以可交换态为主，Pb化学形态以铁锰氧化态为主，与旺长期相比，成熟期根际土壤有效态Cd、Pb含量分别下降了21%、44%;（3）与旺长期相比，成熟期植株根、茎、叶Pb含量分别降低了18%、54%、42%，根、茎、叶Cd含量则增加了14%、163%、49%，成熟期植株各部位减少了对Pb的吸收，增加了对Cd的吸收。从积累分布看，成熟期Pb大部分累积在叶和籽粒内，Cd大部分累积在叶和茎内;（4）相关性分析显示，玉米根系草酸含量与根际土壤有效态Cd、交换态Pb、铁锰氧化态Pb含量呈显著或极显著负相关，且茎Pb、叶Pb含量与根际土壤有效态Pb含量呈现极显著正相关。因此，玉米可通过根系分泌低分子量有机酸，影响根际土壤重金属化学形态与生物有效性，进而影响植株对重金属的吸收累积。

关键词：镉铅含量;低分子量有机酸;化学形态;生物有效性

中图分类号：X503

文献标识码：A

文章编号：1008-0457（2021）03-0007-08

国际DOI编码：10.15958/j.cnki.sdnyswxb.2021.03.002

Characteristics of Low-molecular-weight Organic Acids Secreted by Roots，Cd and Pb Forms and Accumulation Characteristics in Zea mays L.Grown in a Lead-Zinc Mining Area

ZHANG Xinshuai，ZHONG Wei，ZHAN Fangdong，HE Yongmei，LI Bo，LI Mingrui，YANG Zhixin*

（College of Resources and Environmental Sciences，Yunnan Agricultural University，Kunming，Yunnan 650201，China）

Abstract：

Maize is the main summer crop in the farmland surrounding the lead-zinc mine in Yunnan province.Field experiments were conducted to study the content of the low-molecular-weight organic acid，the form of cadmium （Cd） and plumbum （Pb），and the accumulation characteristics of Cd and Pb in the maize rhizosphere grown in farmland around the mining area.The results showed that：（1） The main secretion of maize roots in the vigorous period was citric acid and oxalic acid; the maize root secretions in the mature period were mainly tartaric acid and oxalic acid，and the secretion of oxalic acid was significantly increased compared with the vigorous period.（2） The chemical form of Cd in the maize rhizosphere soil was mainly exchangeable，and that of Pb was mainly the oxidation state of iron and manganese.Compared with the prosperous period，the available Cd and Pbcontent in the rhizosphere soil of the mature period decreased by 21%and 44%，respectively.（3） Compared with the prosperous period，the Pb content in the roots，stems and leaves of the mature plants decreased by 18%，54% and 42%，while the Cd content in the roots，stems and leaves increased by 14%，163%，and 49%.Various parts of the plant at the mature stage reduced the absorption of Pb and increased the absorption of Cd.From the perspective of accumulation and distribution，most of Pb accumulated in leaves and grains，and most of Cd accumulated in leaves and stems.（4） Correlation analysis showed that the content of oxalic acid in maize root system was significantly or extremely negatively correlated with the content of available Cd，exchanged Pb，and iron-manganese oxidation state Pb in rhizosphere soil，and the content of Pb instem and leaf were effective in rhizosphere soil.The content of state Pb showed a very significant positive correlation.Therefore，maize could secrete low-molecular-weight organic acids through the root system，which affects the chemical form and bioavailability of heavy metals in rhizosphere soil，and then affects the absorption and accumulation of heavy metals by plants.

Keywords：

Cd and Pb content;Low-Molecular-Weight Organic Acid;chemical form;bioavailability

铅锌矿作为中国重要的战略性矿产资源，在开采、冶炼过程中会产生大量的尾矿和烟尘，它们通过废渣渗漏、大气沉降等作用进入矿区周边农田，使得农田土壤重金属污染严重[1]。……