| In this paper,Kandelia candel (L.) Druce hypocotyls were cultivated in sand and treated with 15% seawater for 60 days under laboratory conditions. The influence of increasing concentrations of Napthalene and Pyrene (0,0.1,1 and 10mg/L) on hypocotyl germination and growth,photosynthesis metabolism,water metabolism and membrane protection system were observed to inquire into the ecophysiological responses of mangrove K. candel to PAHs phytotoxicity. Moreover,the concentration and distribution of parent polycyclic aromatic hydrocarbons(PAH's) in surface sediment,underground root and leaf residue of mangroves in Jiulong River Estuary(Fugong,north and south shores of Haimen Island,Baijiao),neighbouring Xiamen Western Harbour(Dong Islet) and Dongzui Harbour(Fenglin) were examined. The profile and main source of PAHs as well as the relationship between BCFsv values for mangrove underground root and phyhsico-chemical parameters of PAHs(water solubility and octanol-water partitioning coefficients) were investigated. The result showed:1. Effect of Napthalene(Nap) and Pyrene(Pyr) different concentration on hypocotyl germination of Kandelia candel in sand culture is obvious. Hypocotyl germination of Kandelia candel showed no significant difference from control group at concentration of 0.1mg/L for Nap and Pyr. When at concentration of 1 mg/L and 10mg/L,Nap showed a significant inhibition on hypocotyl germination of K. candel,but showed no inhibition on first pair of leaves;At concentration of 10mg/L,Nap showed a significant inhibition on the second pair of leaves. As for Pyr,when at concentration of 0.1mg/L and Img/L,Hypocotyl germination of Kandelia candel showed no significant difference from control group;At concentration of 10mg/L,Pyr produced a significant inhibition on the second pair of leaves. The effect on the growth of K. candel seedling exposed to PAHs for 60 days could be manifested by the appearance of roots. At concentration of 10mg/L,the root of K. candel seedling were wide and short,had few or no root hairs. Especially for Nap,above 70% of roots turned rotten and black,others were half rotten. It could be inferred from above thatNap had stronger inhibition on germination K. candel hypocotyl than Pyr.2. With increasing concentrations of Pyr and Nap,a decrease in the number and length of roots were observed. The growth of K. candel seedling roots showed no significant difference from control group at concentration of 0.1 mg/L for both Pyr and Nap,- When at concentration of 1 mg/L,Nap showed a significant inhibition on the growth of roots. Whereas Pyr showed a significant inhibitionat at concentration of 10 mg/L. So Nap also had stronger inhibition on the growth of K. candel seedling roots than Pyr. When at low concentration,Pyr and Nap simulated the high growth of K. candel seedling. At concentration of 1 mg/L,Pyr produced inhibition,Nap still produced stimulation. At concentration of 10 mg/L,both showed strong inhibition. The effect of Nap and Pyr on the growth of K. candel seedling leaves were similar. The growth of K. candel seedling leaves showed no significant difference at low concentration,was inhibited at concentration of 1 mg/L and 10 mg/L. Correspondingly the biomass of various parts of K. candel seedling and the total biomass showed no significant difference from control group at low concentration of Pyr and Nap. With increasing concentrations of PAHs the biomass of various parts of K. candel seedling and the total biomass tended to decrease,the extent of inhibition by Nap was obviously greater than by Pyr.3. The chlorophyll content(ch chlb and chla+chlb) in relative stable leaves of K. candel seedlings increased with increasing concentrations of Pyr and Nap,which suggested simulatory effect of PAHs;However,net photosynthetic rate in leaves of K. candel seedlings decreased,the extent of inhibition by Nap was also greater than by Pyr.4. After 60 days of exposure to Nap and Pyr,the soluble sugar content in leaves of K. candel seedlings increased with increasing concentrations... |
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