环境因子对水生植物复氧及除污效果的影响

Reoxygenation and Decontamination Effect of Aquatic Plants under Different Levels of Environmental Factors

单一环境因子对水生植物复氧能力影响较大且存在不少分歧,因此研究了环境因子(光照、温度、pH值、盐度)对水生植物复氧和去除污染物能力的影响。结果表明:菹草在光照强度为80%自然光(9 600 lx)条件下,复氧能力最高,OE值达到127×10^(-5);黑藻、浮萍、香蒲的复氧能力随着光照强度的升高而增加。高温不利于水生植物向水体复氧,因此在夏季高温时,可采用机械曝气方式向水体复氧。水生植物在中性环境中可向水体输送较多的氧气,在整个pH值梯度范围(6. 0～8. 0)内,沉水植物、挺水植物去除TN、TP、COD的能力较高,浮叶植物对富营养盐的去除效果欠佳。水生植物复氧能力随盐度的升高而明显下降,在盐度过高区域(0. 8%),黑藻、菹草、浮萍和荇菜几乎没有复氧能力;水生植物对水体中TN、TP和COD的去除能力随盐度的增加也呈下降趋势。

The effects of environmental factors on the aquatic plants reoxygenation are complicated. The influences of environmental factors （ illumination, temperature, pH, and salinity） on the ability of aquatic plants to recover oxygen and remove pollutants were studied. With 80% light intensity （9 600 lx）, Potamogeton crispus showed the highest reoxygenation capacity and the OE value reached 127× 10^-5. The reoxygenation capacity of black algae, duckweed, and cattail increased with the increase of the light intensity. High temperature inhibited the aquatic plants from restoring DO, therefore it was rec- ommended to utilize mechanical aeration methods under summer temperatures. Aquatic plants could transport more oxygen to the water in a neutral environment. Within the pH gradient from 6.0 to 8.0, submergent and emergent plants were more efficient in the removal of TN, TP and COD comparing to floating-leaf plants. The reoxygenation capacity of aquatic plants decreased significantly with the increase of salinity. In high salinity water （0.8%）, black algae, Potamogeton crispus, duckweed, and Nym- phoides peltatum barely had any reoxygenation capacity. The purification capacity of the six aquatic plants for TN, TP and COD decreased as the salinity increased.