Effects of oily wastewater on the growth of Kandelia candel seedlings
Li Mei1, Chen Guizhu2, Zheng Songfa1, Zhang Jinhong3
1. Research Institute of Tropical Forestry, CAF, Guangzhou 510520; 2. Research Institute of Environmental Science, Zhongshan University, Guangzhou 510275; 3. Institute of Environmental Protection of Guangzho
Kandelia candel simulated wetland was set up in a greenhouse. The system consisted of three subsystems, one-year old K. candel seedlings, sediment and water. The synthetic oily wastewater with five various concentrations, i.e. 50 mg·L-1, 100 mg·L-1, 200 mg·L-1, 400 mg·L-1, 800 mg·L-1 and 15‰ artificial seawater (CL i.e. control) had been discharged into wetland twice a week for one year. The effects of oily wastewater on the growth of K. candel seedlings are as follows; Applied with oily wastewater at concentrations of 200 mg·L-1, 400 mg·L-1 and 800 mg·L-1, some seedlings expressed damage symptoms including curling of the leaves, chlorosis, with reddish pigmentation etc. To the 800 mg·L-1 group, seedlings expressed damage symptoms firstly and the number was the most. The survival percentages of seedlings applied with 200 mg·L-1, 400 mg·L-1 and 800 mg·L-1 oily wastewater were 95.92%、85.18% and 59.25% respectively. Discharge of oily wastewater at lower concentration could stimulate the seedling growth of K. candel. As to the 50 mg·L-1 group, yearly increment values of stem height, stem diameter and biomass were higher than CL with very significance level. Treated with 200 mg·L-1 oil wastewater, yearly increment values of stem height, stem diameter and biomass were close to CL. To the 100 mg·L-1 group, yearly increment value of stem height was higher than CL significantly. As to the 400 mg·L-1 and 800 mg·L-1 groups, plant growth was obviously inhibited. As a conclusion, K. candel had resistance and adaptability to oily wastewater, but oily wastewater at higher concentration would be harmful to K. candel.
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