水环境中蓝藻毒素研究进展

随着社会的发展,水体富营养化日益严重,藻类及藻毒素严重污染了水环境,不仅给传统净水工艺带来不利影响,增加了水处理难度,而且严重威胁人类健康和生命安全,已成为全球性的环境问题.本文较详细地介绍了蓝藻的起源、特性及其危害,并综述了有关其检测方法及防治措施.最后,对蓝藻毒素降解技术的发展方向进行展望.     

藻毒素的生物降解研究进展

近年来蓝藻水华污染产生的有毒代谢产物藻毒素对水生生态系统和人类健康构成严重的威胁。生物降解技术尤其是生物滤池由于运行维护费用低并且不产生有毒副产物,已广泛应用于去除藻毒素。然而,水处理过程中可能存在的生物降解多种藻毒素效果的信息少有收集,这在越来越多不同种类的藻毒素能同时在水源地中检测出来的情况下更加重要。综述了目前所有藻毒素生物降解性的相关研究进展,分析了影响藻毒素生物降解的因素,并探讨了目前藻毒素生物降解技术如何在水处理过程中应用优化去除藻毒素效果,为运用生物降解方法控制或去除各种藻毒素提供理论指导。     

光照强度对伪鱼腥藻生长及光合活性的影响

为研究光照强度对一种常见淡水水华蓝藻伪鱼腥藻(Pseudanabaena sp.)生长及光合活性的影响,根据自然界光照强度范围,设计5个光照强度梯度,采用实验室纯培养方法,开展为期16 d的实验研究.实验过程中对伪鱼腥藻的生物量水平、叶绿素荧光参数和关键色素比例进行跟踪监测,结果发现,在500～2 500 lx,伪鱼腥藻的最适生长光照强度为1 500 lx,其比增长速率从高到低排列为1 500 lx,1 000 lx,2 000 lx,2 500 lx,500 lx.伪鱼腥藻的光合活性受光照强度影响显著,培养一段时间后,伪鱼腥藻的光合速率和光能利用效率与光照强度显著负相关,第11天相关系数分别为-0.939(P0.05)和-0.978(P0.01),半饱和光强与光照强度显著正相关,第11天相关系数为0.976(P0.01).伪鱼腥藻属于低光照强度耐受型蓝藻,且具备自身调节机制应对光照不足或光照过强,易于在光照不足或光强波动较大的水体中占据优势,其暴发相对不易受水深和光强的限制,不宜采用垂向扰动或遮光的抑藻措施对其进行控制.上述发现为地表水体中伪鱼腥藻的预测和控制提供了理论基础.     

Hydrogen-rich gas production by steam gasification of char derived from cyanobacterial blooms (CDCB) in a fixed-bed reactor: Influence of particle size and residence time on gas yield and syngas composition

Char derived from cyanobacterial blooms (CDCB), by-product of fast pyrolysis of cyanobacterial blooms from Dianchi Lake (Yunnan Province, China) at a final pyrolysis temperature of 500 °C were used as feedstock material in this study. Steam gasification characteristics of CDCB were investigated in a fixed-bed reactor to evaluate the effect of particle size (below 0.15 mm, 0.15–0.3 mm, 0.3–0.45 mm, 0.45–0.9 mm, 0.9–3 mm) and solid residence time (3, 6, 9, 12, 15 min) on gas yield and composition, and experiments were carried out at bed temperature range of 600–850 °C, steam flow rate of 0.178 g/min. The results showed that solid residence time played an important role on steam gasification process, while particle size presented less effect on gasification process; proper particle size and longer residence time were favorable for dry gas yield and carbon conversion efficiency (CCE). At the same time, higher reaction temperature reduced influence of particle size on gasification process, and smaller particle size required less residence time for reaction completed. Maximum dry gas yield and CCE reached 1.84 Nm³ kg⁻¹ and 98.82%, respectively, achieved at a temperature of 850 °C, flow rate of 0.178 g/min, solid residence time of 15 min and particle size range of 0.45–0.9 mm.     

云龙天池水库季节性蓝绿藻水华成因及其对水质的影响研究

全球变暖背景下湖库发生蓝绿藻水华的成因及其对水质的影响是充满争议的热点环境问题。云龙天池水库是云龙天池国家级自然保护区的主要水源地,开展其水质变化研究具有重要战略意义。本研究利用多参数水质监测浮标系统(AMT—FB301)对该水库开展了连续四个月(2022.1.14—5.11)的高分辨率(时间间隔30 s)蓝绿藻和水质监测工作。结果显示,蓝绿藻在3月早春时节发生水华现象。在月间、月际和日际尺度上,水体中的氨氮含量均与蓝绿藻丰度高度正相关,表明在这类尚未发生明显富营养化的水体中,营养条件仍然是调控蓝绿藻水华发生的最主要因素。突然的升温也可能成为诱发蓝绿藻暴发的关键因素,但充足的营养供应是前提条件。蓝绿藻水华的发生导致了水库的水质明显下降(浊度增加,溶解氧降低)。所以,在未来持续升温背景下,控制外源营养输入仍然是改善这类水库水质和防控蓝绿藻水华发生的最有效途径。     

HJ-1B和Landsat卫星蓝藻水华监测能力评估——以洱海为例

蓝藻水华是富营养化湖泊共同面临的问题。遥感技术为快速、大范围水华监测提供了可能,选取遥感数据应首先明确不同卫星的水华监测能力。以洱海为例,对比分析HJ-1B和Landsat卫星在内陆中小湖泊水华监测的时间和空间监测能力,评价两者在水华监测中的适用性及优势。结果表明:两者均能有效识别水华,提取水华分布细节信息,相比MODIS更适合用于中小湖泊水华监测;进一步分析表明,综合两者数据监测蓝藻水华,可以更加客观统计水华时间特征,描述水华空间分布发展规律,对于其它中小湖泊利用遥感手段辅助水华监测具有参考意义。     

Fingerprinting Chamaesiphon populations as an approach to assess the quality of running waters

Cyanobacterial communities are highly diverse in freshwaters and respond rapidly to changing environments. Previous studies have highlighted variations in the structure and composition of epilithic cyanobacterial communities in response to eutrophication in watercourses. In the present study, changes in benthic cyanobacterial communities from Guadalix River (Spain) biofilms were examined using temperature‐gradient gel electrophoresis (TGGE) in conjunction with microscopic examination of field‐fixed samples, focusing on populations of one of the dominant cyanobacteria: Chamaesiphon. Environmental characteristics were determined in order to characterize the trophic status of the sampling sites. The presence of cyanobacteria in the river was determined from complex TGGE patterns, band extraction, and subsequent sequencing of 16S rDNA gene fragments. The microscopic observations revealed that the unicellular genus Chamaesiphon and the filamentous genus Phormidium were dominant in the studied locations. Within the 2 genera, 4 Chamaesiphon populations were identified (Chamaesiphon fuscus, Chamaesiphon starmachii, Chamaesiphon subglobosus, and Chamaesiphon polymorphus) and Phormidium was represented at the sampling sites by the Phormidium autumnale morphotype. TGGE banding patterns differed among samplings sites as a function of water quality. The genetic analysis revealed 4 phylotypes within the genus Chamaesiphon and 1 phylotype within the classic P. autumnale clade. Chamaesiphon phylotypes were not equally distributed in all the sampling locations. Some phylotypes were related to low nutrient concentrations, while others were associated with eutrophic conditions. Our results support the use of fingerprints of Chamaesiphon populations obtained by TGGE to examine changes in water quality.     

一种蓝藻生物量长期原位实时监测仪的研制

近年来,各类水体蓝藻水华灾害频繁发生,导致水体生态系统功能退化和破坏,并严重危害到水产养殖和用水安全.对水体中蓝藻生物量进行长期实时监测是防治蓝藻水华灾害的一项必要措施.基于蓝藻中所含藻蓝蛋白的特征荧光效应,即采用620 nm波长的强光激发出645 nm波长的荧光并通过检测其强度来推算水中蓝藻生物量,最终研制出了一种能对水体中活体蓝藻生物量实现原位快速监测的仪器,辅以专门设计的自清洗功能使之能长期免于人工维护和校准.为满足对广阔水域的时空分布动态监测的需要,采用GPS技术获得各测点地理位置信息,还采用无线通信技术实现其与监测中心的远程实时在线数据通信,藉此扩展了其实用范围.实验结果表明,蓝藻生物量与检测值的线性相关系数可达0.98以上,可见检测值能精确地反映蓝藻浓度的变化.