营养元素对微囊藻毒素好氧生物降解的影响

通过室内模拟实验,研究了好氧条件下MCLR在太湖沉积物-水体系中的生物降解过程,着重探讨了外加碳源、不同形态的氮源和磷源对该过程的影响.结果表明,好氧条件下沉积物中MCLR经过8 d明显的迟滞期,于第16 d降解到检测限以下,说明太湖沉积物中的土著微牛物具有降解MCLR的能力.外加氨氮、硝氮和碳源对MCLR的降解速率均没有显著影响(P≥0.05),而外加溶解性磷源可显著促进MCLR的降解(P<0.01),说明在天然水体沉积物中,磷可能是MCLR好氧降解过程的限制性营养元素.这一结果对于正确评价水体中MC的微生物降解能力以及准确预测MC的浓度变化趋势具有指导意义.

Effects of Nutrient Elements on the Biodegradation of Microcystin Under Aerobic Conditions

The aerobic biodegradation process of microcystin LR( MCLR) in the sediment-water system was investigated through a series of well-controlled microcosm experiments using sediments from Taihu Lake as inocula. The effects of the additions of nutrient elements(carbon, nitrogen and phosphorus) on the degradation process were assessed. The results showed that MCLR was degraded to below the detection limit at the 16th day with a lag period of 8 days, indicating that indigenous microorganisms in the sediment of Taihu Lake were capable of degrading microcystin under aerobic conditions. The addition of glucose or nitrogen (NH_4-N and NO_3-N) had no obvious effect on the biodegradation of MCLR( P≥0.05), whereas the addition of phosphorus could significantly promote the biodegradation of MCLR( P<0.01). These results suggest that phosphorus might be the limited nutrient for aerobic biodegradation of MCLR in natural sediment. These findings are helpful for evaluating the biodegradability of MC and predicting the tendency of MC pollution in eutrophic water bodies.