Experimental Design
All plants are grew in the hydroponic environment, which can remove the effects of solid tailings and study the alone effects of tailing water. In the whole experiment, the hoagland solution is used to satisfy the nutrient requirment of plants. Besides, each treatment group consists of one big water container (120L) and three smaller root-growth hydroponic containers (30L). Tree species are planted in small hydroponic containers with foam board supporting them. These containers are connected by tubes. And one water pump will be placed at the bottom of the large water container to maintain the solution circulation between the large and small containers.
There are four treatments in this study. Each treatment has different growth condition and solution:
A. Aerated control: 50% Hoagland solution
B. Aerated tailing water treatment: 50% Hoagland solution : tailing water (1:1, v/v)
C. Hypoxic control: 50% Hoagland solution
D. Hypoxic tailing water treatment: 50% Hoagland solution : tailing water (1:1, v/v)
A. Aerated control: 50% Hoagland solution
B. Aerated tailing water treatment: 50% Hoagland solution : tailing water (1:1, v/v)
C. Hypoxic control: 50% Hoagland solution
D. Hypoxic tailing water treatment: 50% Hoagland solution : tailing water (1:1, v/v)
Data Collection
Fig 4. LI-6400 XT portable photosynthesis system
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Treatments were applied for eight weeks. After the eight-week period, all plants were harvested. Six plant samples of each tree species from each treatment were selected to measure the physiological parameters, including net photosynthesis, transpiration rate, intercellular CO2 concentration, and water use efficiency, and so on, with LI-6400XT portable photosynthesis system.
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Reclamation Tree Species
Fig 5. Black Spruce, Jack Pine, Trembling Aspen, and Paper Birch. (From left to right)
The plant species selected in the first experiment include four tree species. They are Jack Pine, Black Spruce, Trembling aspen, and paper birch, respectively. Among them, Jack Pine and Black Spruce are coniferous species. The other two species are deciduous species. Besides, trembling aspen and paper birch are also pioneer species. They can not only tolerate the harsh environment to colonize on the disturbed land but also grow quickly. At the same time, the trembling aspen is the dominant tree species of the boreal forest of Northern Alberta, which also makes it more adaptable to the local environment. All in all, these tree species are considered having high potential to reclaim the tailing soil in Northern Alberta.