表层底泥翻耕对太湖藻源性湖泛的预控作用

Effects of plow-tillage on the prevention and control of algae-caused black bloom

表层底泥已被证实是引发或诱发太湖湖泛发生的主要因素,但能否通过像控制湖泊内源污染的翻耕方式对湖泛形成预控,则有待与过程有关的实验研究.模拟研究太湖易发湖泛区底泥翻耕对藻源性湖泛的控制作用,跟踪监测不同翻耕深度和翻耕后时长,对照和处理组上覆水的视觉、嗅觉、营养盐和挥发性硫化物浓度,以及表层底泥理化性质的变化.结果表明,未翻耕的对照组在模拟实验中发生了湖泛,翻耕10 cm和翻耕20 cm差异不大,但翻耕后时长对湖泛发生影响较大.刚翻耕后(1 d)即进行藻源性湖泛模拟的处理组发生了湖泛,但在程度和持续时间上均低于对照组;翻耕180 d和540 d的处理组,10 cm和20 cm翻耕深度均未发生湖泛.合理选择翻耕的施工时间,可以有效预防和控制湖泛的发生.

Black-bloom was an environment issue that often occurred recently and the polluted surface sediment was known as the most important reason for its occurrence. Plow-tillage was a cost-effective and practicable engineering measure which was designed for internal loading control. Based on the simulated experiment in laboratory,effects of plow-tillage on the prevention and control of algae-caused black bloom was studied. The color and odor,nutrient concentration of overlaying water,the concentrations of volatile sulfur compounds and physicochemical characteristic of sediment were measured. The results were showed as follows： black bloom occurred in both control check set and treatment sets l day after plow-tillage for the two diffirent plow-tillage depths,but its duration and degree in control check set were more serious than those in treatment sets l day after plow-tillage. The treatment sets of 180 and540 days after plow-tillage of both depths didn＇t experienced black bloom during the whole simulated experiment. Overall,the appropriate project time of plow-tillage can prevent the occurrence and control the degree of algae-caused black bloom.