常见重金属在翅碱蓬(Suaeda heteroptera)根际沉积物系统季节迁移变化

SEASONAL TRANSFORMATION VARIATION OF COMMON HEAVY METALS IN SUAEDA HETEROPTERA-RHIZOSPHERE SEDIMENT

应用原子吸收光谱法(AAS)和电感耦合等离子体原子发射光谱法(ICP-AES)对翅碱蓬-根际沉积物系统常见重金属(Cu、Pb、Zn和Cd)总量和不同化学形态含量进行了季节跟踪测定。结果表明,系统中Cu、Zn、Pb和Cd环境化学行为呈现显著季节变化。从化学形态上看,根际沉积物中Cu和Pb在生理周期内均以残渣态为主,有机结合态在夏季和秋季达较高值。Zn在生理周期内均以交换态为主且随季节变化明显,碳酸结合态和铁锰结合态随季节变化不明显。Cd以残渣态为主,交换态在春季达最高。从总量上看,根际沉积物中的Cu、Zn、Pb的总量在夏季和秋季具有较高值。从系统迁移情况看,植物对Cu和Pb吸收量均为冬季>春季>秋季>夏季,且大部分限制于地下;其体内分布除秋季Pb为根>叶>茎外,其它时期均为根>茎>叶。Zn吸收量为秋季>夏季>冬季>春季,且绝大部分被吸收至地上。Zn吸收和分布取决于根际沉积物生物有效含量;总之,春季植物体重金属向根际沉积物迁移。夏季和秋季,Cu、Pb和Cd由根际沉积物向植物体迁移变化并不明显,而Zn正好相反。4种元素在冬季均为根际沉积物向植物体内迁移。

Environmental chemical behaviors of Cu, Pb, Zn, and Cd in Suaeda heteroptera-rhizosphere sediment were studied using samples from a wetland near Liaohe Oil Field, North China. These metals show distinct seasonal variations. In the rhizosphere sediment, Cu and Pb are the major component in the whole physiological cycle in residuals state, and the content of their organic bound species reached high level in blossom period, seasonal variation of the exchangeable was clear. Carbonates and Fe-Mn oxides reached peak value in different periods. Zn exists dominates the whole physiological cycle in exchangeable state and varies seasonally, while its residuals took the second place, and its organic bound is the least; seasonal variations of carbonates and Fe-Mn oxides are weak. Cd is in residual state mainly, and its exchangeable reaches the highest level in seeding period. The total content of Cu, Pb and Zn in rhizosphere sediment is in the orders of fruit periodseedling periodflower periodgrowth period, and rootstemleaf except Pb in rootleafstem. The metal accumulation and distribution depends on plant physiological mechanism.