Microcystin Accumulation in Nile Tilapia, <i>Oreochromis niloticus</i>and Giant Freshwater Prawns, <i>Macrobrachium rosenbergii</i>in Green Water System Cultivation

Phytoplankton including blue-green algal or cyanobacterial blooms frequently occurred in aquaculture ponds. Some cyanobacteria produced cyanotoxins that may accumulate in the food web and eventually in the aquaculture products. In this study, accumulatation of microcystins in Nile tilapia (Oreochromis niloticus) and giant freshwater prawn (Macrobrachium rosenbergii) cultured in green water system was investigated.Nile tilapia was cultured in green water system and fish food;green water system with Microcystis aeruginosa Kützingand fish food and green water system with M. aeruginosa. Giant freshwater prawn was cultured: in green water systems with and without toxic M. aeruginosa. Microcystins of 8.32±0.76 and9.35±1.45μg·kg—1 d.w. were detected in fish cultured in green water system with M. aeruginosa and fish food and in green water system with M. aeruginosa, respectively. Microcystins of 14.42±1.63 μg·kg—1 was found in prawn samples. It implied that aquaculture products were likely to be contaminated with microcystins. This finding is useful for aquaculture in terms of food safety.

亚硝态氮对铜绿微囊藻和四尾栅藻生长的影响

采用室内培养法,将铜绿微囊藻和四尾栅藻分别置于5种含不同质量浓度亚硝态氮（NO2^--N）（0.5 mg/L、1.0 mg/L、2.0 mg/L、4.0mg/L和8.0 mg/L）的培养液中,培养10 d,测定不同质量浓度NO2^--N对铜绿微囊藻和四尾栅藻生长的影响。结果表明,0.5-8.0 mg/L的NO2^--N可激活铜绿微囊藻的亚硝酸氧化酶和亚硝酸还原酶,进而促进铜绿微囊藻的生长。四尾栅藻因仅具有亚硝酸还原酶,因此只能利用0.5-2.0 mg/L的NO2^--N,其利用能力远没有铜绿微囊藻强。培养8 d后,铜绿微囊藻培养液中NH4^＋-N和NO2^--N的质量浓度明显升高,而NO3^--N质量浓度的变化不大;四尾栅藻培养液中NH4^＋-N、NO2^--N和NO3^--N质量浓度的变化不大。研究表明,低于8.0 mg/L的NO2^--N可促进铜绿微囊藻的生长,高于2.0 mg/L的NO2^--N抑制四尾栅藻的生长。

压力酸浸制备双价聚硅硫酸铝铁及其除藻性能

目的利用钾长石提钾后的固体渣,开发双价多功能絮凝剂,研究其除藻性能,实现钾长石的综合利用,为除藻等水处理提供新型药剂。方法利用压力酸浸(PAL)工艺提取固体渣中的铝、铁,通过引入Fe(II)源,制备得到含Fe(II)的双价聚硅硫酸铝铁(PSAFS),以铜绿微囊藻(Microcystis aeruginosa)为模式藻,研究PSAFS的混凝除藻效果及其与H2O2的耦合效应。结果当硫酸浓度为2.8 mol/kg,固液比为1:3时,在105℃下反应2 h,PAL可提取近100%的铝和85.6%的铁。含Fe(II)的双价聚硅硫酸铝铁新型絮凝剂对于Microcystis aeruginosa具有优异的去除效果,引入Fe(II)可以拓宽絮凝剂应用的p H范围。同时,在H2O2存在时,产品明显增加了藻细胞的失活。结论以钾长石提钾后的固体渣为原料,采用PAL工艺,可绿色经济地制备含Fe(II)的双价PSAFS,是一种具有应用前景的多功能絮凝剂。