The Interaction Between Mangrove Plant(Kandelia Candel) And Soil Polluted By Mercury

The paper talked about changes of physiological and ecological parameters in K. candel under the influence of Hg,as well as changes of mercury,methylmercury and mercury species in soils under the influence of K.candel,which revealed the interaction between mangrove plants and mercury-contaminated soil,which would lay the foundation for further study of the intrinsic relationship between heavy metals mercury and plants.In this paper,mangrove Kandelia candel was experimental material.K.candel were cultivated in soils containing different amount of Hg,Set three Hg gradient stress group:54mg/kg,93mg/kag and145mg/kg.Cultivation time is 58d,84d and 101d.During the experiment,record seedlings germination,the height of seedling growth,leave size.In 58d,84d and 101d,sample seedlings and measure root growth and water content,chlorophyll content,the largest and actual photochemical efficiency,soluble protein content,activity of antioxidant enzymes,total Hg and MeHg content of roots and leave.Simultaneously,collect soil samples and measure the total Hg,methylHg and Hg species and content.Conclusions are as follows:1.With the extension of cultivation time and the increase of Hg content in soil, roots became large and coarse,even rot.Hg obviously inhibited height growth;leaf size and water content of seedlings.2.Hg inhibit PSⅡphotosynthetic activity.With the increase of Hg concentration,Fv /Fm,Fv'/Fm' and content of chlorophyll and soluble protein decreased.Low concentrations of Hg promoted SOD activity while high concentrations of Hg inhibited SOD activity.POD activity of leave and Hg content was negatively correlated.Sensitivity of three protective enzymes to Hg was CAT＞POD＞SOD,and the sensitivity of three protective enzymes to methylHg was SOD＞POD＞CAT.Curves analysis showed their relevance with Hg was CAT＞POD＞SOD.3.After planting candel,volatile Hg increased,higher than the control.With the extension of cultivation time and increase of Hg concentrations,B1 form of Hg(combinations of Hg(Ⅱ) ions and some simple organic,inorganic Hg(Ⅱ) complexes,as well as components of bond polarity combined with the soil) and Fe-Mn oxide-bound Hg increased,while organic substance-bound decreased.The decrease of residual Hg indicated rhizosphere of candel can activate Hg.Total Hg in the soil continuously decline,whlie MeHg decreased first and then increase.4.With the extension of cultivation time and increase of Hg concentrations,total Hg content of roots and leave increased,while MeHg content increased first and then decreased significantly.The results showed there was negative correlation between MeHg content and cultivation time.5.Correlation regression analysis showed Hg content in leave was significantly positively correlated with B1 form Hg,while Hg content of root came mainly from volatile Hg and B1 form Hg.There was a significant positive correlation between total Hg content in the soil and Hg content in leave,Hg content in roots and Hg content in leave was also significantly positively correlated;MetHg content in leave and MeHg content in roots was also significantly positively correlated.