改性黏土絮凝海洋原甲藻对水体中氮、磷的影响研究

Effects of flocculation of Prorocentrum micans by modified clay on nitrogen and phosphorus

通过对比研究典型有害微藻海洋原甲藻(Prorocentrum micans Ehrenberg)自然消亡(A1组)及改性黏土絮凝(A2组)两种体系,考察两体系中氮、磷等主要水质因子的变化情况.结果表明,改性黏土能有效去除P.micans并影响其后期生长状态,0.4g/L改性黏土添加3.5h后去除率可达60%以上,且藻密度无二次增长.改性黏土絮凝藻华过程中能有效去除水体营养元素,A2组DIP和DIN较A1组分别降低85%和35%.另外,添加改性黏土对水体有机氮、磷影响值得关注,第33d A2组TON和TOP较A1组分别减少约120,6μmol/L.改性黏土对有机氮、磷存在一定的埋存保护作用,通过吸附絮凝、螯合等作用使有机氮、磷脱离水体系统,而自然消亡体系中的微藻消亡后将通过分解、矿化等过程快速进入水体参与再循环.该研究系统阐述了改性黏土絮凝P.micans对水体营养环境的影响,以期为现场治理提供理论支持.

Harmful algal blooms （HABs） occurred frequently in coastal water around the world over the past decades. Flocculation of algal cells by modified clay has been proven to be an effective method and was the only practical strategy applied in the field, particularly in Asia. To assess the long-term ecological effects of this method, the study investigated the variation of two major nutrients during succession of cultured dinoflagellate Prorocentrum micans Ehrenberg （P. micans, A 1） flocculated with modified clay （MC,A2）. More than 60% ofP micans cells were efficiently removed by 0.4g/L of MC within 3.5h, and cells were no rebooming in A2. The results indicated that MC removed 26% of TN, 42% of TP, 85% of DIP, 35% of DIN, respectively, compared with TON and TOP concentrations in AI, it has been decreased of 120μmol/L and 6gmol/L by MC on day 33, respectively. Simultaneously, the study speculated that MC treatment controlled the nutrient exchange （between water and sediment） by blocking and sealing the organic-clay matrix in the surface areas of sediments. The study would benefit the further explore of long term environmental effects of the MC application for HABs＇ mitigation.