The Effect Of Lead And Cadmium Pollution On Growth Of Spartina Alterniflora

Coastal ecosystem is an open ecological system. In recent years, ecosystems in coastal areas haveexperienced different levels of pollutions due to the high development of economy and fastened industrial progressing, among which, pollution from heavy metals is one of the core problems. Being the China’s earliest coastal wetland reserve, Yancheng Natural Reserve of Jiangsu Province has been also reported to has heavy metal pollution recently, as the cadium (Cd) and lead (Pb) levels are far much higher than the background determinded in1979. The alien species Spartina alterniflora was introduced into China in1979, due to its outstanding contribution to coastal protection and land formation. However, the species is under debating on bioinvasion recently. Many researches have tried to uncover its expansion mechanism, while still no confident conclusions have been made. There is no report showing the relationship between the changes on ecosystem heavy metals and the growth of this species as well as the expansion of its community. This research used the clonal seedlings of S. alterniflora, to imitate the series levels Cd, Pb pollution and their combined effect. The main conclusions are as followed:(1) Except roots, Biomass from different organs of S. alterniflora decreased with the increasing of Cd, Pb levels (P>0.05). Cd and Pb conbined pollution showed similar effect on biomass, with statistical signicance on aboveground, stem-and total biomass (P<0.05). Compared with simily heavy metal pollution, combined pollution was more serious.(2) The contents of Chlorophyll a and total Chlorophyll level of S. alterniflora were reduced by Cd, Pb and their combined pollution. Lower levels of Cd and Pd positively stimulated the contents of chlorophyll b and carotenoid, whereas higher levels of Cd, Pb and the combined pollution showed inhibition on all index.(3) The quantum efficiency of open PSⅡ, Fv/Fm, of S. alterniflora was negatively correlated with the levels of heavy metal pollution, significance was found with Pb and combined pollution but not Cd. Quantum yield of PSII photochemistry (OPSⅡ) and instant electron transport rate (ETR) were also inhibited by Pb and Cd pollution. Still, the combined pollution exerted stronger influence on the index than simple pollution.(4) This study further improved the extraction protocol of flavonoids from S. alterniflora. Based on this, flavonoid content of S. alterniflora was found to be increased with the experimental dose of Pb or Cd and Pb pollution. Such situation was not happened with Cd pollution.It is concluded that the experimental high levels of Cd and Pb pollution had negative effects on growth of S. alterniflora. Cd and Pb both inhibited the photosynthetic index and biomass of S. alterfniflora, and combined pollution was even serious than simple pollution. The content of flavonoids of S. alterniflora was increased by the pollutant situation, indicating that flavonoids may play an important role in helping the plant to resisting the damage from heavy metal.