洱海水体氮磷时空分布及其对ρ(Chla)的影响

为探讨影响洱海藻类生长的主要水质因子,对洱海近20年的水质变化及2009—2010年水质和ρ(Chla)时空变化进行了研究. 结果表明,1992年以来上覆水中ρ(TN)、ρ(TP)和ρ(Chla)总体呈上升趋势,近年来有所下降,ρ(Chla)与ρ(TN)和m(N)/m(P)呈显著正相关. 2009年5月—2010年12月上覆水中ρ(TN)为0.20～0.96mg/L,ρ(TP)为0.018～0.042mg/L,ρ(Chla)为6.02～22.48μg/L；年内ρ(TN)和ρ(TP)最高值均出现在7—8月,m(N)/m(P)和ρ(Chla)最高值出现在8—9月,ρ(Chla)与m(N)/m(P)呈极显著正相关.随水深增加,ρ(TN)和ρ(TP)呈上升趋势,ρ(Chla)呈下降趋势；1d内ρ(TN)最高值出现在17:30前后,ρ(TP)和ρ(Chla)最高值出现在14:30前后,ρ(Chla)与ρ(TP)呈显著正相关；年内7—8月水质最差. 洱海水体ρ(Chla)年际变化主要受ρ(TN)和m(N)/m(P)影响,年内变化主要受m(N)/m(P)影响,而日变化则主要受ρ(TP)影响. 

Temporal and Spatial Distribution of Nitrogen and Phosphorus in Water Body of Erhai Lake and Effect on Concentration of Chlorophyll-a

The temporal and spatial changes of concentrations of total nitrogen (TN), total phosphorus (TP) and chlorophyll-a (Chla) of the overlying water in Erhai Lake from 1992to 2010year were analyzed, and the predominant water quality factors affecting algal growth were also discussed. The results showed that the concentrations of TN, TP and Chla in Erhai Lake increased since 1992and decreased slightly in recent years. The contents of Chla significantly positively correlated with the TP concentration and the value of N/P ratio. The concentrations of TN in the overlying water were in the range of 0.20-0.96mg/L, and that of TP were in the range of 0.018-0.042mg/L, and that of Chla were in the ranged of 6.02-22.48μg/L. Within one year, the highest concentrations of TN and TP appeared from July to August, while the highest N/P ratio and Chla contents occurred from August to September. Meanwhile, the contents of Chla showed a significant positive correlation with the ratio of N/P(R=0.6247, P＜0.01). The concentrations of TN and TP showed an upward trend with the increasing water depth, reversely, the contents of Chla showed downward trend with increasing water depth. Within one day, the highest TN concentration was at 17:30, while the highest TP concentration and Chla content was at 14:30. Meanwhile, the contents of Chla showed a significant positive correlation with the TP concentration(R=0.7841, P＜0.05). On the whole, the water quality of Erhai Lake tended to decrease since 1992, and the worst water quality occurred from July to August within one year. In the water body, the inter-annual variation of algae biomass was associated with the TP concentration and the ratio of N/P, the seasonal variation was monthly controlled by N/P, the diurnal variation depended on the TP concentration.