pH值对凤眼莲不同种养周期太湖底泥磷素迁移转化的影响

[目的]本文旨在探索凤眼莲种养和空闲期内对不同pH值富营养化水体-底泥中系统磷素转化的影响。[方法]通过模拟试验，设置上覆水pH值分别为6.0、7.5和9.0，分析凤眼莲种养期和空闲期的水体、植物、底泥之间磷素的迁移转化规律。[结果]种养凤眼莲期间，底泥间隙水正磷酸盐含量有不同程度的升高，从大到小的处理依次为碱性、中性和酸性，与底泥总磷下降趋势一致，表明磷素由底泥通过间隙水向上覆水转移。不同pH值条件下上覆水磷含量均有降低，降幅由高到低的处理pH值依次为7.5、6.0和9.0，种养凤眼莲42~56 d为水体净化的最佳阶段。凤眼莲生长性状从好到差的处理依次为中性、碱性和酸性，主要受水体pH值和磷素含量的影响，且各生长参数表明种养20~60 d为干物质主要积累阶段。另外，在凤眼莲收获后的空闲期，酸性水体系统中上覆水磷素含量变化不大，中性和碱性水体中磷素含量随pH值的升高和空闲期的延长呈明显的增加趋势。[结论]凤眼莲的生长状态优先受水体pH值影响，其次受水体磷素含量影响。本试验条件下，种养凤眼莲60 d可开始逐步采收，能获取最大生物量和氮、磷富集量或吸收量，且上覆水为中性或偏碱性时，凤眼莲采收后需采取相应措施，以降低底泥磷释放对水体的继续影响。
[Objectives]The paper aims to explore the effect of Eichhornia crassipes planting and idle periods on different pH eutrophic water-sediment phosphorus transformation systems.[Methods]When the overlying water pH was 6.0,7.5 and 9.0,we observed the phosphorus exchange on plant-water-sediment during planting period and idle period of E. crassipes in the simulation experiment.[Results]During the planting period of E. crassipes,sediment interstitial water concentration of phosphorus increased in different degrees,in order from big to small was alkaline,neutral and acid. This trend of change was consistent with the downward trend of total phosphorus in sediment,which showed that phosphorus transferred from the sediment to the overlying water through the interstitial water. At the same time,the phosphorus content of overlying water decreased under different pH conditions,and the decrease from high to low was neutral,acidic and alkaline. 42-60 days was the best stage for water purification. The growth state of E. crassipes from good to poor in neutral,alkaline and acid treatment,the growth parameters showed that the main influencing factors were water pH and phosphorus concentration,and planting 20-60 days was the accumulation phase of dry matter. Besides,during the idle period of E. crassipes,in acidic water system,the concentration of phosphorus in overlying water changed little,and the concentration of phosphorus in neutral and alkaline water increased obviously with the increase of pH and the increase of idle period.[Conclusions]The growth state of the E. crassipes priority was in affected by pH,and then was affected the phosphorus content in water. Under the simulation experiment conditions,the E. crassipes harvest could be began 60 days after planting gradually,in order to obtain the maximum biomass and nitrogen and phosphorus uptake or accumulation.We should take corresponding measures on the recovery in neutral and alkaline water,to reduce the phosphorus release from sediment to impact on water