微囊藻毒素检测方法的研究进展

随着水体富营养化日益严重,有毒蓝藻水华引起的污染事件在世界范围内频繁发生,其产生的毒素对生物有潜在的危害。所以迫切需要建立一种工作原理简单易行、分析速度快、灵敏度较高的统一的检测方法,对水体中特别是饮用水源中的微囊藻毒素进行检测。文章简要介绍了近年来发展起来的几类微囊藻毒素检测技术,以及微囊藻毒素检测技术尚要解决的问题和未来的发展方向。     

蓝藻水华对太湖水柱反硝化作用的影响

反硝化作用是湖泊水体最主要的脱氮过程,对减轻湖泊的氮素污染和富营养化控制具有重要意义.蓝藻水华暴发和衰亡可能会通过改变水体氮素循环途径及微环境来促使反硝化作用直接在水柱中发生,加速氮的去除.为了验证这一假设,取太湖湖水添加不同生物量的蓝藻和连续10 d的NO_3~--N、PO_4~(3-)-P营养盐,进行蓝藻生长与降解对反硝化影响的模拟实验,测定蓝藻水华期水体藻类生物量和各形态氮浓度的动态变化,同时利用~(15)N同位素添加培养结合膜进样质谱仪(MIMS)实时定量测定反硝化速率.结果表明,蓝藻在生长期吸收氮素转变为颗粒氮,在衰亡期藻细胞通过降解矿化释放了大量的NH_4~+-N,继而转化为NO_3~--N,为反硝化作用提供底物,是大幅度促进水体反硝化作用的关键;反硝化速率(以N2计,下同)最高达到(1 614. 52±301. 57)μmol·(m~2·h)~(-1),是同时期最低蓝藻生物量组反硝化速率[(534. 45±242. 18)μmol·(m~2·h)~(-1)]的3倍,实验结束时添加初始蓝藻生物量倍数最高组的TN去除率达最高(40. 02%),是未添加蓝藻组TN去除率(17. 72%)的2. 26倍,说明蓝藻堆积会显著促进反硝化作用的强度,加速水体氮素的去除.蓝藻衰亡时反硝化速率的快慢受NH_4~+浓度的影响显著,表明附着在藻团的微生物的耦合硝化-反硝化作用是氮盐去除的主要途径.本研究结果表明,水华蓝藻生长期快速吸收氮素转变为颗粒氮,蓝藻死亡降解后通过耦合硝化-反硝化作用加速氮素去除,这可能是太湖夏季氮素浓度降低的原因之一.     

Cyanobacterial flora and the physico-chemical environment of six tropical fresh water lakes of Udaipur, India

The cyanobacteria and physico-chemical environments of sic tropical fresh water lakes of Udaipur,India were investigated.These lakes receive varying nutrient inputs from different sourcesi.Altogether 51 species of cyanobacteria were recorded.Species composition varied between lakes and between seasons.Lake VI(Beghdara),which receives nutrients from natural sources only,differed considerably from the others in water chemistry and composition of dominated species.Lake Ⅱ(Swaroop Sagar),eutrophied due to sewage inputs,was species poor.Non-diazotrophs,represented by 27 species,dominated during summer.With few exceptions,N2-fixing species,bothe heterocystous and unicellular diazotrophs (represented by 24 species),were dominant during winter.Microcystis aeruginosa,Phormidium sp.and Anabaena flos-aque were ther dominant taxa of lakes characterized by sewage eutrophication.The study shows that both species diversity and community composition were affected by water chemistry.     

Removal of Microcystins by Phototrophic Biofilms. A Microcosm Study (6 pp)

Background, Aims and Scope Microcystins (MCs) are a family of natural toxins produced by cyanobacteria (blue-green algae). As a result of eutrophication, massive cyanobacterial blooms occur more frequently and MCs represent important contaminants of freshwater ecosystems. Bacterial biodegradation is considered a main mechanism for MC breakdown in environmental conditions. While existing studies were mostly focused on MC biodegradation by planktonic bacteria, our experiments examined the fate and kinetics of MC degradation in river-originated phototrophic biofilms and investigated factors influencing the rate of MC removal. Methods The fate of dissolved MCs was studied in laboratory microcosms with different composition (containing water only, water with phytoplankton and/or phototrophic biofilms). Biofilms originated from river ecosystem were pre-incubated under various conditions (with/without presence of cyanobacterial biomass or model organic substrates: glucose and protein - casein). Changes in MC concentration (0-14 days) in water columns were measured by HPLC DAD after external additions of purified MCs (160 μg L-1, MC-LR and MC YR), and halftimes (t1/2) of MC removal were estimated. Results and Discussion The slow degradation of MC was revealed in tap water (t1/2 ~ 14 days) and river water without cyanobacteria (t1/2 ~ 8 days). Enhanced removal occurred in the presence of natural planktonic cyanobacteria (t1/2 ~ 44 h), most probably due to microorganisms associated with the biomass of cyanobacterial bloom. More rapid MC elimination occurred in the variants containing phototrophic biofilms, and was particularly pronounced at those biofilms pre-cultivated in the presence of cyanobacterial blooms (t1/2 ~ 20 h). Much slower removal was observed in the variants simulating possible substrate-dependent induction of microorganism metabolism (biofilms pre-incubated with glucose: t1/2 ~ 35 h, and casein: t1/2 ~ 80 h). After termination of experiments, total amounts of MCs accumulated in the biofilms were below 5% of the initial toxin level revealing significant biodegradation processes. Conclusion The microcosm studies contributed to understanding of the environmental fate of MCs and revealed a rapid biodegradation by phototrophic biofilms. The rate of MC elimination depends on history of biofilm community, previous contact with cyanobacteria seems to be a selective factor improving the biodegradation potential. Recommendation and Outlook Our results experimentally showed a positive role of biofilms in MC elimination during water treatment processes such as bank filtration or slow sand filtration, and could eventually serve for further research of biofilm-based technological applications for MCs removal in small-scale drinking water treatment facilities.     

Current Status of Mathematical Models for Population Dynamics of Prymnesium parvum in a Texas Reservoir1

Grover, James P., Jason W. Baker, Daniel L. Roelke, and Bryan W. Brooks, 2010. Current Status of Mathematical Models for Population Dynamics of Prymnesium parvum in a Texas Reservoir. Journal of the American Water Resources Association (JAWRA) 46(1):92-107. DOI: 10.1111/j.1752-1688.2009.00393.x Abstract: Blooms of the harmful alga Prymnesium parvum have apparently increased in frequency in inland waters of the United States, especially in western Texas. A suite of mathematical models was developed based on a chemostat (or continuously stirred tank reactor) framework, and calibrated with data from Lake Granbury, Texas. Inputs included data on flows, salinity, irradiance, temperature, zooplankton grazing, and nutrients. Parameterization incorporated recent laboratory studies relating the specific growth rate of P. parvum to such factors. Models differed in the number of algal populations competing with P. parvum, and whether competition occurred only by consumption of shared nutrients, or additionally through production of an allelopathic chemical by one of the populations, parameterized as cyanobacteria. Uncalibrated models did not reproduce the observed seasonal dynamics of P. parvum in Lake Granbury, which displayed a maximum population in late February during a prolonged bloom in cooler weather, and reduced abundance in summer. Sensitivity analyses suggested two modifications leading to predictions that better resembled observations. The first modification greatly reduces the optimal temperature for growth of P. parvum, an approach that disagrees with laboratory experiments indicating a strong potential for growth at temperatures above 20°C. The second modification increases the growth rate of P. parvum at all temperatures, in models including cyanobacterial allelopathy. Despite these adjustments, calibrated models did not faithfully simulate all features of the seasonal dynamics of P. parvum.     

壳聚糖-纳米金属絮凝剂絮凝沉降水华蓝藻研究

研究了壳聚糖与纳米钛、纳米铁或妫水湖沉积物絮凝剂絮凝沉降水华蓝藻的效果。结果表明:在壳聚糖浓度为3 mg/L情况下,与妫水湖沉积物和纳米钛相比,纳米铁絮凝沉降蓝藻细胞的效果最好,在10 min内可以絮凝沉降79.5%以上的水华蓝藻细胞。进一步研究显示,在pH值为5~9的范围内,随着pH值的降低,絮凝沉降藻细胞的效率逐渐提高,pH值为5时10 min内可以絮凝去除89.6%以上的水华蓝藻细胞,具有重要的研究价值与应用价值。     

太湖蓝藻水华预警监测综合系统的构建

近年来随着浅水型湖泊的富营养化进程不断加快,蓝藻水华暴发现象也频繁出现,采用科学、全面的手段对太湖蓝藻暴发进行预警十分必要。根据太湖蓝藻预警监测中使用的现场巡视、卫星遥感、实验室分析、自动监测等监测技术手段,分别建立各自监测系统,结合各监测系统特点和相互关系,对太湖蓝藻水华预警监测综合系统的构建进行了探讨,以期能够更好地开展太湖蓝藻水华预警监测工作,为确保太湖地区饮用水安全,提高环保部门应对太湖蓝藻水华暴发的能力,为政府决策提供技术支持和保障。     

Aspects and prospects of algal carbon capture and sequestration in ecosystems: a review

Long-term storage of carbon dioxide (CO₂) and other forms of carbon in non-atmospheric reservoirs is called carbon sequestration. Selective anthropogenic enrichment of the atmospheric carbon pool is causing dire environmental problems, thereby necessitating remediation by mitigation. Algae possess efficient carbon concentrating mechanisms and consequently high photosynthetic rates which make them suitable candidates for biosequestration of CO₂. Globally, nearly half of the atmospheric oxygen is generated by algal photosynthesis despite the fact that algae account for less than 1% of photosynthetic biomass. In water bodies, algae are responsible for creating the ‘biological pump’ that transports carbon from the upper sunlit waters to the depth below. A diverse array of photoautotrophs ranging from prokaryotic cyanobacteria to eukaryotic algae such as Chlorophytes, and even protists like euglenoids, contribute to this ‘biological pump’. It operates in a variety of aquatic ecosystems ranging from small freshwater ponds to the oceans where it has been most extensively studied. Two separate but intricately linked processes constitute this ‘biological pump’, viz. the ‘organic carbon pump’ and the ‘calcium carbonate pump’. The present review discusses the natural CO₂ sequestration processes carried out by algae and cyanobacteria in their native ecosystems.     

不同存放时间太湖蓝藻产沼气潜力

对不同存放时间蓝藻(新鲜蓝藻、存放3个月、6个月和9个月)进行厌氧消化处置,分析反应过程中沼气量、代谢产物和酶活等变化,获得各自的产沼气潜力。研究结果表明,存放6个月蓝藻组的产沼气率最大,为120.5 mL/g TS,是新鲜蓝藻组的1.29倍。Gompertz模型拟合表明,随着存放时间的延长,最大产沼气量(Pmax)先增大后减小,最大比产气率一直增加。存放3个月蓝藻组的VFA在第6天达到最大,为1 575.4 mg/L,而存放9个月蓝藻组的VFA在第2天达到最大,为1 116.5 mg/L。存放3个月蓝藻组的最大中性蛋白酶酶活为1 203.4μg/(g TS.h),比新鲜蓝藻组提高212.8μg/(gTS.h)。脱氢酶酶活随着蓝藻存放时间的增加呈现先增加后减小的趋势。     

藻源可溶有机质对17β-雌二醇生物降解的影响

为探究藻源可溶有机质(COM)及其生物老化过程对湖泊水体中17β-雌二醇(E2)生物降解的影响特征,通过模拟生物老化,得到5种不同生物活性的COM样品:S0(78％)>S1(67％)>S2(36％)>S3(13％)>S4(1％).结果表明,经过60h的避光培养实验,相同浓度(8mgC/L)的COM样品均提高了微生物群落...