夏季滇池不同来源溶解性有机磷特征及其生物有效性

Characteristics and bioavailability of dissolved organic phosphorus from different sources of Lake Dianchi in summer

夏季选取了滇池不同来源（滇池湖体、入湖河流和大气降雨）水样,研究了其溶解性有机磷（DOP）含量及分布特征,并利用酶水解技术表征了其 DOP 生物有效性.结果表明,滇池湖体、入湖河流和大气降雨 DOP 浓度分别在0.001~0.117,0.002~1.722,0.006~0.112mg/L（平均0.027,0.197,0.037mg/L）,分别占溶解性总磷（DTP）的18.3%~92.5%,4.2%~100%,25.4%~100%（平均55.3%,60%,58.9%）,不同来源 DTP 均以DOP 为主,入湖河流 DOP 浓度明显高于滇池湖体和大气降雨.不同来源 DOP 酶可水解磷（EHP）浓度分别为n.d.~0.058,n.d.~0.673,n.d.~0.031mg/L（平均0.017,0.064,0.010mg/L）,分别占 DOP 的0%~127.5%,0%~105.6%,0%~55.6%（平均77.9%,38.7%,23.2%）.不同来源DOP酶水解率（EHP/DOP）较高,滇池湖体DOP酶水解率明显高于入湖河流和大气降雨.不同来源DOP时空分布特征明显,且其生物有效性存在较大差异.其中,滇池湖体EHP以活性单酯磷和类植酸磷为主,入湖河流和大气降雨EHP以活性单酯磷为主,尤其是大气降雨二酯磷和类植酸磷含量较少,滇池湖体、入湖河流和大气降雨DOP生物有效性依次降低.不同来源DOP是与溶解性反应磷（SRP）同等规模的生物可利用磷源,二者共同维持了滇池富营养化.滇池治理要从全流域出发,考虑不同来源各形态磷对水质的影响.

The content and distribution characteristics of dissolved organic phosphorus （DOP） were studied by collecting water samples from different sources of Dianchi Lake （overlying water, inflowing rivers and rainfall） in summer,and the bioavailability of these DOP were also characterized by emzymatic hydrolysis. The results indicated that the concentrations of DOP from overlying water, inflowing rivers and rainfall ranged from 0.001~0.117, 0.002~1.722 and 0.006~0.112mg/L （average, 0.027, 0.197 and 0.037mg/L）, respectively, and constituted 18.3%~92.5%, 4.2%~100% and 25.4%~100% （average, 55.3%, 60% and 58.9%） of dissolved total phosphorus （DTP）, respectively. DOP predominated their DTP of the different sources samples, and the concentrations of DOP from inflowing rivers were significantly higher than that from overlying water and rainfall. The concentrations of enzymatically hydrolysable phosphorus （EHP） of DOP from different sources ranged from not detectable （n.d.）~0.058, n.d.~0.673 and n.d.~0.031mg/L （average, 0.017, 0.064 and 0.010mg/L）, accounting for 0~127.5%, 0~105.6%and 0~55.6%（average, 77.9%, 38.7%and 23.2%） of DOP, respectively. The enzymatica hydrolysis ratio of DOP （EHP/DOP） were relatively high and EHP/DOP from overlying water was significantly greater than that from inflowing rivers and rainfall. DOP from different sources showed evident characteristic of spatial and temporal distribution and their bioavailability had great differences.Labile monoester P and phytate-like P represented primary portions of EHP from overlying water, whereas, labile monoester P accounted for major sections of EHP from the inflowing rivers and rainfall, especially for EHP of the rainfall which had relatively low concentrations of diester P and phytate-like P. The bioavailability of DOP from overlying water, inflowing rivers and rainfall declined in turn. DOP from different sources represented the available P of equivalent magnitude to soluble reactive phosphorus （SRP）, that meant EHP and SRP keep the eutrophication of Dianchi Lake together. So the effects of different phosphorus species from different sources on water quality should be considered for protection of Dianchi Lake from the whole watersheds.