长江中下游部分湖泊沉积物碱性磷酸酶分布及其作用研究

沉积物磷负荷在湖泊富营养化的发生与恢复过程中具有关键作用,其释放受物理、化学与生物机制调节,而碱性磷酸酶催化有机磷的矿化,故当为促进沉积物磷循环的重要因素。本文讨论了长江中下游部分湖泊沉积物碱性磷酸酶分布及其在磷释放过程中的作用。五里湖疏浚与未疏浚区以及太湖、巢湖、龙感湖、东湖、月湖、龙阳湖、莲花湖等不同湖泊的不同区域表层沉积物碱性磷酸酶活性(APA)明显不同,这种空间异质性与湖泊富营养化程度相联系。此外,APA随沉积物的深度递减,或在中间与较深层次出现峰值,且具明显的季节性。上述事实以及APA对抑制剂的不同响应方式暗示酶存在形态的多样性(同工酶)。苯丙氨酸(Phe)明显提高月湖与五里湖沉积物APA,沉积物与Phe相互作用并静置一天之后,生物可利用性磷(SRP)的释放量明显增加。再者,Phe可抑制月湖沉积物APA,沉积物与Phe相互作用并静置一天之后,SRP释放量无明显变化,溶解有机磷(DOP)的释放量则明显增加。因此,释放的SRP部分来自某些活跃的有机磷的酶促水解,沉积物碱性磷酸酶在内源磷的释放以及富营养化过程中具有重要作用。

A Study on Distribution and Roles of Alkaline Phosphatase in Sediments of Some Lakes in the Middle and Lower Reaches of the Yangtze River

Phosphorus loadings in sediments play an important role in lake eutrophication and the progress of its recovery.The Phosphorus release is controlled by physical,chemical and biological mechanisms.Alkaline phosphatase catalyzes remineralization of organic phosphorus and then it may be an important factor accelerating Phosphorus cycling in sediments.In this paper,we discussed distributions and roles in the phosphorus release of alkaline phosphatase in sediments of some lakes in the middle and lower reaches of the Yangtze River.Alkaline phosphatase activity(APA) in surface sediments in the dredged and undredged zones of the Lake Wulihu and the different areas of the Lake Taihu,Chaohu,Longganhu,Donghu,Yuehu,Longyanghu and the Lianhuahu are quite different.The spatial heterogeneity is related to the degree of eutrophication.Moreover,APA decreased with the sediment depth and may peak in the intermediate and deeper layers showing a seasonal variation.The enzyme differently responded to its inhibitors.All the facts implied that the enzyme occurred in various forms(isoenzymes).L-Phenylalanine(Phe) enhanced APA in the sediments of the Lake Wulihu and the Lake Yuehu.Reacted with Phe and incubated for one day,the sediments released the bioavailable phosphate(SRP) with significantly higher concentration,while it inhibited APA,in the sediments of the Lake Yuehu.Reacted with Phe and incubated for one day,the sediments released significantly larger amounts of dissolved organic phosphorus,without increasing the SRP concentration.Hence,the SRP released resulted,at least partially,from the hydrolysis of some liable organic phosphorus mediated by APA.Alkaline phosphatase in lake sediments plays an important role in the release of internal P loadings and eutrophication.