长江口盐沼植物对营养盐和重金属的吸收、分布与滞留研究

Study on Uptake,distribution and sequestration of nutrients and heavy metals by salt marsh plants in Changjiang Estuary

测定3种盐沼植物体内TN、TP、重金属Cu、Zn、Pb和Cd的含量,计算了3种盐沼植物地上部分TN、TP和重金属库的大小。结果表明,3种盐沼植物在养分的分配模式上显著不同,3种盐沼植物地上部分重金属含量均低于地下部分;互花米草地上部分的养分库和重金属库均大于芦苇和海三棱镳草,表明其对养分和重金属的吸收与滞留效率更高。如果从湿地植物净化的角度来考虑,收获互花米草对河口环境的净化作用最佳,特别对P的去除效率最高;但另一方面,互花米草的入侵将会显著改变长江口湿地生态系统的生物地球化学循环过程,如提高沉积物中重金属的生物可利用性,有可能把更多的重金属输入河口水体和食物网,使湿地成为重金属的源而不是汇。

The total nitrogen, phoshorus and heavy metals（ Cu.Zn.Pb and Cd） were measured in three salt marsh plants such as Phragmites australis, Spartina alterngqora and Scirpus mariqueter. The standing stock of nutrient and heavy metals in the aboveground part is calculated. The result shows that the distributing pattern of nutrients is very different in three salt marsh plants. The concentration of heavy metals in the aboveground is lower than that in the belowground. The pool size of nutrient and heavy metals in S. alterniflora is higher than in other salt marsh plants because of its large aboveground biomass. It show that its sequestrating rate is higher. If considering the biological purification by harvesting the plants, the rate of purification is the highest by harvesting S. aherniflora aboveground biomass, especially getting rid of phosphorus in the wetland. On the other hand, the invasion of S. aherniflora maybe significant changes the biogcochemical cycle process in the wetland ecosystem of Changjiang Estuary, such as improving the bioavailability of heavy metals in the sediment, and importing more heavy metals from the estuarine wetland into estuary water and estuarine food web. Thus, the estuarine wetland possibly becomes the source of the heavy metals.