草、藻型湖泊水体生态及理化特性的实验对比

2006年9月,根据营养水平和种植水草的差异设计了6个浅水湖泊模拟系统,实验用水草为菹草(Potamogeton crispusLinn.)和马来眼子菜(Potamogeton malaianus-Miq).在15个月实验期间,通过多次监测各系统的景观外貌和水质,对草、藻型湖泊生态及理化特性的差异进行研究,得出以下结论:(1)草、藻型系统分别对应清水和浊水2种状态,景观外貌差异很大.(2)水草可使湖泊系统维持在清水状态,在一定条件下,甚至可使富营养化湖泊维持在清水状态;但是水草腐烂分解等也可使水质迅速恶化,甚至引起湖泊草、藻状态的转变;关键在于,对于不断变化的环境条件,系统内水草能否健康生长.(3)由于营养和生产力水平低,贫营养系统的水质指标随时间变化较小,草、藻型系统间的差异不明显,DO变化范围分别为8.1～14.4 mg·L~(-1)、7.5～11.6 mg·L~(-1),pH 8.71～9.89、8.25～9.22,TP 0.006～0.012 mg·L~(-1)、0.006～0.053 mg·L~(-1),TN 0.11～0.71 mg·L~(-1)、0.10～0.83 mg·L~(-1),NH_4~+-N 0.01～0.17 mg·L~(-1)、0.01～0.26 mg·L~(-1),PO_4~(3-)-P 0.002～0.012 mg·L~(-1)、0.000～0.008mg·L~(-1).(4)由于水草和藻类的大量生长等,中营养与富营养系统湖水的DO、pH、水温和NH_4~+-N的日变化明显,日变化曲线呈“⌒”形,且具有季节性变化规律;由于水草向底泥中输氧气等原因,与藻型湖泊相比,草型湖泊水中TP、TN和NH_4~+-N的浓度较低,PO_4~(3-)-P浓度较高,草、藻型系统的TP均值分别为0.16、0.51 mg·L~(-1),TN 1.30、8.32 mg·L~(-1),NH_4~+-N 0.19、0.43mg·L~(-1),PO_4~(3-)-P 0.07、0.01 mg·L~(-1).

Microcosmic experimental comparison of ecological and physicochemical characters between macrophytic and algal lakes

In order to study differences between a macrophytic and an algal lake, 6 micro-simulation systems of shallow lakes were established with different nutrition levels and macrophytes in September, 2006, and water plants adopted are Potamogeton crispus Linn and Potamogeton malaianus Miq. During the 15-month experimental period, the conclusions are drawn based on the regular measured data regarding the appearance characteristics and the water quality of the simulation systems. They can be addressed as follows: (1) A macrophytic lake and a algal lake are in the clear water state and the turbid water state respectively characterized by the individual appearance characteristics. (2) The macrophytes play a crucial role in maintaining a clear lake ecosystem, and they can maintain a eutrophicated lake in the clear water state under some conditions. However, decomposition of the massive macrophtes may deteriorate water quality rapidly, and sometimes results in the change of a lake state. The important thing is that whether the macrophyte can grow healthfully in the changing environment. (3)There is almost no change of the water quality over time in a oligotrophic lake because of the poor production and the nutrition limitation. Regardless of the macrophyte growth, the oligotrophic system is in the clear water state all the time. The extent of DO in the oligotrophic macrophytic and algal systems are 8.1～14.4 mg·L~(-1), 7.5～11.6 mg·L~(-1) respectively; pH 8.71～9.89, 8.25～9.22; TP 0.006～0.012 mg·L~(-1), 0.006～0.053 mg·L~(-1); TN 0.11～0.71mg·L~(-1), 0.10～0.83 mg·L~(-1); NH_4~+-N 0.01～0.17 mg'L~(-1), 0.01～0.26 mg·L~(-1); PO_4~(3-)-P 0.002～0.012 mg·L~(-1), 0.000～0.008 mg·L~(-1). (4) Daily change curves of DO, pH, water temperature and NH_4~+-N present "⌒"shape because of the abundance in macrophyte and al-gae in the mestrophic or eutrophic lakes, and the water quality varies seasonally. Compared to the algal lakes, the concentration of PO_4~(3-)P is higher, while the concentrations of TP, TN and NH_4~+-N are lower in the macrophytic lakes due to the growth of the macrophytes. The average TP concentrations in the macrophytic and the algal systems are 0.16 and 0.51 mg·L~(-1) respectively, TN 1.30, 8.32 mg·L~(-1); NH_4~+-N 0.19, 0.43 mg·L~(-1); PO_4~(3-)-P 0.07, 0.01 mg·L~(-1).