Trace Elements Of Saline Soils And Suaeda Salsa In The Northeastern Coastal Region Of The Jianzhou Bay

Jiaozhou bay is a semi-enclosed bay in the central Huanghai Sea and is located on the south bank of Shangdong Peninsula. In recent years, anthropogenic activities especially industrial and domestic pollution have made a strong impact on the ecological environment. Thus, the studies on the accumulation, transfer and transform of chemical pollutants (e.g., heavy metals) by Suaeda Salsa and bioremediation are significative. This study was based on the saline soils and Suaeda Salsa in the northeastern coast of Jiaozhou Bay to study the distributions of alkali metals, alkaline-earth metals and heavy metals in saline soils and Suaeda Salsa and accumulation characteristics of Suaeda Salsa. They were significative and valuable for probing into the bioremediation of saline soils by Suaeda Salsa. The main conclusions of this study were as follows:1. The concentrations of alkali metals and alkaline-earth metals (e.g., Li, Rb, Cs, Sr and Ba) in saline soils of the northeastern coast of Jiaozhou Bay were consistent. Among these metals, the concentrations of Li, Sr and Ba were higher than the soil background values, whereas the concentrations of Rb and Cs, especially that of Cs were lower than the soil background values. The Li/Cs ratio was close to Ba/Sr ratio. Moreover, there were significant positive correlations between Li and Cs and between Sr and Ba, suggesting that the soils of this area mainly came from the weathering production of mineral having high potassium (e.g., potash feldspar), which was coincident with the parent materials (i.e., granite) of Qingdao. The variations of Cu and Zn concentrations in saline soils of the northeastern coast of Jiaozhou Bay were great and their concentrations were higher than the soil background values; the variations of Pb, Cd and Cr concentrations were not obvious and their concentrations were higher than the soil background values; the variations of As and Mo concentrations were not obvious and their concentrations were lower than the soil background values; the distribution was similar for V ,Co and Ni, the concentrations of which in the northern part were somewhat higher than the soil background values whereas in the southern part were slight lower than the soil background values. As, Co, Ni, V, Mo, Cu, Zn and Pb of saline soils in the northeastern coast of Jiaozhou Bay mainly came from parent materials and were not influenced by anthropogenic activities, whereas Cr and Cd mainly originated from industrial and agricultural inputs by Qingdao besides the parent materials.2. Although the accumulation of alkaline-earth metals by Suaeda Salsa was more than that of alkali metals, all enrichment factors (EFs) of them was less than one, suggesting that Suaeda Salsa posed no accumulative ability on alkali metals and alkaline-earth metals. The sequence of EFs by Suaeda Salsa was: Sr>Li>Rb>Cs>Ba, and the EFs of them in overground part of Suaeda Salsa were less than one, suggesting that Suaeda Salsa had not general characteristics of accumulation plants. Transfer efficiencies of Li and Sr by Suaeda Salsa were great and most of them were transferred into the overground part of Suaeda Salsa, where the Li accumulation was high in leaves whereas the Sr accumulation was high in stems. Transfer efficiency of Rb by Suaeda Salsa was not obvious. Similarly, transfer abilities of Cs and Ba by Suaeda Salsa also were low and most of Cs and ba was limited in roots.The uptake of Cu and Zn by Suaeda Salsa was significantly higher than that of other heavy metals, which was related to the nutrient behaviors of Cu and Zn. With respect to other heavy metals, Cr, Pb, V and Ni concentrations in Suaeda Salsa were relatively high. The accumulation Mo by Suaeda Salsa was most obvious and its EFs were more than one, followed by Cu, Zn, Cd and As, indicating that Suaeda Salsa had some accumulation of Cu and Zn. However, the accumulation of other heavy metals by Suaeda Salsa was not obvious and their EFs were less than one. The sequence of EFs in the roots of Suaeda Salsa was: Cd>As>Cu>Zn>Mo>Co >Ni>V>Pb>Cr. The sequence of EFs in the stems of Suaeda Salsa was: Mo>Cd>Zn>Cu>As, Co, Ni>Pb, Cr>V. Particularly, the accumulation of Mo and Cd by the stems of Suaeda Salsa was significantly higher than others. The sequence of EFs in the leaves of Suaeda Salsa was: Mo>Cd>Zn>Cu>As>Ni>Co>Pb, Cr>V. Particularly, the accumulation of Mo, Cd and Cu by the leaves of Suaeda Salsa was obvious.In conclusion, the transfer efficiency of Mo by Suaeda Salsa was highest and most of Mo was transferred to overground part, and was followed by Cu and Zn. The average concentrations of Cu and Zn in stems and leaves accounted for 45.2% and 65.9% of total concentrations, respectively. The uptake and transportation of other heavy metals by Suaeda Salsa was low, likely related to resistance reaction of plants on nonnutrients.