| In the experiment, Erhai Lake sediments were used as the research object, six kinds exocellular enzyme activity include APA were determined at five sampling for different redional, freeze-dried the same samples and determined the content of organic matter,total phosphorus and phosphorus forms,total nitrogen and transferable nitrogen. Analyzed the vertical distribution characteristics of exocellular enzyme activity in different regional of Erhai Lake, and discussed how C, N, P metabolism affected by exocellular enzyme activity. Results showed that:(1) In the columnar sample sediments of Erhai Lake:the range of changes with six exocellular enzyme activity like that:PPO activity was 5.75～36.90μg·g-1·h-1, POD activity was 17.54～63.80μg·g-1·h-1, CAT activity was 0.821～1.041μg·g-1·h-1, AKP active was 63.89-600.25μg·g-1·h-1,invertase activity was 86.02～445.20μg·g-1·h-1, protease activity was 1.5～31.5 gelatin units.(2) The distribution characteristics of exocellular enzyme activity:in the vertical, most exocellular enzyme activity reduce with depth from surface, and the surface activity significantly higher than bottom and amplitude with depth.In the region, the order for PPO active was northern> southern> central, POD active was southern> central> northern, CAT activity was central> southern> northern, the AKP, invertase, protease activities were southern> northern> central.(3) The same kind of exocellular enzyme activity showed different height and vertical distribution types with different sampling sites and depth in Erhai Lake columnar sample sediments, and not compatriots varies in the same locus of enzyme activity outside the vertical distribution types differs somewhat.(4) Six exocellular enzyme activity and OM content had high correlation at all different regions, including five points with the correlation of PPO active loci was significantly related except E2 point (P<0.05) outside, other four loci were reaching the significant correlation (P<0.01). And protease actiity remove E2 point and E3 point significant correlation (P< 0.05), and the other three points were also reached a significant related (P <0.01).(5) Six exocellular enzymes activity had high correlation with TP content; the highest degree is protease activity. Three sampling points in northern and central were significantly related (P<0.05), two sample points in southern correlation was significant (P<0.01); Six exocellular enzyme activity and four turn nitrogen content of related degree not high with no obvious regularity.(6) Six exocellular enzyme activity had high correlation with TP content, the highest degree was APA, four sampling points related significant (P<0.05), in the south a sampling of correlation was significant (P<0.01); And four different forms of phosphorus correlation studies by APA, as the main research object, the results indicated that the different area five sampling sites APA and Labile-P (r= 0.484) only E2 point fails to achieve significant correlation degree outside, other four bytes sites had three sites (E1, E4, E5) correlation was significant (P<0.01), E3 point correlations also achieve significant correlation (P<0.05).In conclusions, these results demonstrat that:(1) Exocellular enzyme activity have characteristic of related with the environment distribution in Erhai Lake sediments.(2) Exocellular enzymes, especially PPO play an important role in decomposition and corruption budding process of OM; the complete system enzymes have collaborative stimulative effect to carbon metabolism; and the height of protease actiity correlation can speculate carbon and nitrogen have same source in Erhai Lake sediments.(3) Exocellular enzyme activity, especially protease actiity had important contribution for nitrogen metabolism in Erhai Lake sediments. For the transferable nitrogen migration transformation process, exocellular enzymes play a limited role or not directly.(4) Exocellular enzyme activity, especially APA have important contribution for phosphorus metabolism in Erhai Lake sediments. AKP play important role in the Labile-P and RSP migration transformation process,but little role or certain inhibition for content and migration transformation process for Fe/Al-P; and never or small role in migration transformation process of Ca-P. |
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