Editorial special issue on cyanobacterial blooms and water ecological restoration

Environmental Science and Pollution Research -     

Influence of alum on cyanobacterial blooms and water quality of earthen fish ponds

Eruption of blue-green algal blooms occurs frequently in eutrophic lakes and fish ponds, with associated unpleasant odor and horrid scums. In the present study, we conducted a pre-test experiment in 3 m³ outdoor concrete ponds to determine the optimum concentration of aluminum sulfate (alum) required for reduction of the cyanobacterial blooms without negative effect on fish growth. As a consequence, 10 mg L^?1 alum was named as the optimum concentration that was applied in 1000 m³ earthen fish ponds. Obtained results showed that Secchi disc values significantly increased from 10 to 24 cm after 14 days of alum application. Alum-treated ponds showed a reduction in total phytoplankton counts by 94 and 96 % compared to the corresponding controls after 10 and 14 days, respectively. Abundance of blue-green algae in the treated ponds was decreased by 98 % compared to the corresponding control after 14 days of alum application. Consequently, dissolved oxygen, pH, total phosphorus, orthophosphate, and chlorophyll “a” content declined significantly. Our study revealed that using 10 mg L^?1 of alum is an effective way to control cyanobacterial blooms in eutrophic waters, especially in fish ponds, without negative effect in water quality.     

微囊藻毒素-RR的提取和臭氧氧化降解

在对采自云南滇池水华蓝藻细胞中的微囊藻毒素-RR(microcystin-RR,MC-RR)提取并发现其含量达到0.19mg/g(干重)的基础上,重点研究了臭氧氧化降解所提取的MC-RR。结果表明,当反应体系中臭氧浓度为5.7 mg/L时,初始浓度1.9 mg/L的MC-RR在15 min内被完全降解。利用HPLC/ESI/MS对提取的MC-RR及其氧化降解产物质荷比测定发现,降解前MC-RR的质谱图中出现特征离子m/z=1 038.7、m/z=519.8以及m/z=135.0。而降解后的产物质谱图中只有Adda基团中带苯环结构化合物(C9H10O)的特征离子峰m/z=135.0存在,其他2个离子峰完全消失。由此推断反应体系中MC-RR(m/z=1 038.2)在大量臭氧及其.OH自由基全面攻击下,分子结构中Adda基团以及单环结构中的不饱和双键直接被氧化而发生断链,最终形成小分子的有机物。     

An integrated method for removal of harmful cyanobacterial blooms in eutrophic lakes

As the eutrophication of lakes becomes an increasingly widespread phenomenon, cyanobacterial blooms are occurring in many countries. Although some research has been reported, there is currently no good method for bloom removal. We propose here a new two-step integrated approach to resolve this problem. The first step is the inactivation of the cyanobacteria via the addition of H(2)O(2). We found 60 mg/L was the lowest effective dose for a cyanobacterial concentration corresponding to 100 μg/L chlorophyll-a. The second step is the flocculation and sedimentation of the inactivated cyanobacteria. We found the addition of lake sediment clay (2 g/L) plus polymeric ferric sulfate (20 mg/L) effectively deposited them on the lake bottom. Since algaecides and flocculants had been used separately in previous reports, we innovatively combined these two types of reagents to remove blooms from the lake surface and to improve the dissolved oxygen content of lake sediments.     

Critical review of actually available chemical compounds for prevention and management of cyanobacterial blooms

Cyanobacteria proliferation is among the most threatening consequences of freshwater pollution. Health risks from human and other-organism exposure to cyanobacteria have led to an effort to find practical methods for cyanobacterial water-bloom reduction. Hence, methods and techniques have been developed in order to reduce the amount of phosphorus or to decrease the abundance of nuisance phytoplankton species directly in the water bodies (in-lake measures). Although these “acute” methods do not solve the problem of catchment area eutrophication, they are cheaper, easier to manage, and for some areas they are the only way to protect human and environmental health against massive cyanobacterial proliferation. This review summarizes the extent of knowledge and published data about the management using metals (Al, Fe, Cu, Ag, Ca), photosensitizers (hydrogen peroxide, phthalocyanines, TiO₂), herbicides and chemicals derived from natural compounds as fast and efficient removal agents of cyanobacteria. This review concludes that some compounds, when non-persistent and ecotoxicologically acceptable may help to manage cyanobacterial blooms in an efficient way compared to previous methods (e.g. copper sulfate).     

Simultaneous removal of cyanobacterial blooms and production of clean water by coupling flocculation with a rotary drum filter

Environmental Science and Pollution Research - A mechanical harvesting technology based on coupling flocculation with a rotary drum filter (RDF, 35-μm) was applied to remove cyanobacterial...     

Mechanism study on the frequent variations of cell-bound microcystins in cyanobacterial blooms in Lake Taihu: Implications for water quality monitoring and assessments

Although Microcystis-based toxins have been intensively studied, previous studies using laboratory cultures of Microcystis strains are difficult to explain the phenomenon that microcystin concentrations and toxin variants in natural blooms differ widely and frequently within a short-term period. The present study was designed to unravel the mechanisms for the frequent variations of intracellular toxins related to the differences in cyanobacterial colonies during bloom seasons in Lake Taihu, China. Monitoring of Microcystis colonies during warm seasons indicated that the variations in microcystins in both concentrations and toxin species were associated with the frequent alteration of Microcystis colonies in Lake Taihu. High concentration of microcystins in the blooms was always associated with two Microcystis colonies, Microcystis flos-aquae and Microcystis aeruginosa, whereas when Microcystis wesenbergii was the dominant colonial type, the toxin production of the blooms was low. Additionally, environmental factors such as temperature and nutrition were also shown to have an effect on the toxin production of the blooms, and may also potentially influence the Microcystis species present. The results of the present study provides insight into a new consideration for quick water quality monitoring, assessment and risk alert in cyanobacterium- and toxin-contaminated freshwaters, which will be beneficial not only for water agencies but also for public health.     

Analytical insight into degradation processes of aminopolyphosphonates as potential factors that induce cyanobacterial blooms

Environmental Science and Pollution Research - Aminopolyphosphonates (AAPs) are commonly used industrial complexones of metal ions, which upon the action of biotic and abiotic factors undergo a...     

钱塘江河口段水环境现状与保护对策

系统地分析了2001-2008年钱塘江河口段干流地表水、海水及两岸平原河网地表水的水质变迁与现状.结果表明,钱塘江河口段干流地表水水质总体较好,但大部分河段仍未达到<浙江省水功能Ⅸ水环境功能区划方案>的要求,主要的超标项目为NH4+-N和TP,其次为高锰酸盐指数和BOD5,并且DO浓度总体呈现下降趋势;干流海水水质总体较差,主要超标因子为无机氮与活性磷酸盐;两岸平原河网大部分河段水质为<地面水环境质量标准>(GB 3838-2002)V类或劣于GB 3838-2002 V类.为保障钱塘江河口段水资源的持续利用,提出了相关的水环境保护对策.     

基于视频监控的湖泊滨岸带蓝藻水华实时定量监测方法及应用研究

湖泊作为我国主要饮用水源地,其滨岸带蓝藻水华过度堆积,对用水安全以及生态环境造成严重影响。因此,实时定量监测湖泊滨岸带蓝藻水华,是湖泊蓝藻水华防控的关键举措。基于环湖实时视频监控所捕获的水域图像,采用深度学习方法识别蓝藻水华像素,并根据摄像头成像原理及内外参数准确计算每个蓝藻水华像素对应实际蓝藻水华面积,最后统计分析湖泊滨岸带水域的蓝藻水华总面积。实验结果表明,基于VGG16-UNet模型的蓝藻水华像素识别方法的平均交并比与总体精度分别达到了88.74%与94.10%,优于同类方法;且蓝藻水华面积计算值与实测值具有良好的拟合度 (R²=0.97) 。该方法能够及时获取湖泊滨岸带蓝藻水华的覆盖面积及其动态变化过程,对于湖泊水环境治理起着重要作用。     

Biodegradation of multiple cyanobacterial metabolites in drinking water supplies

The fate of multiple cyanobacterial metabolites was assessed in two Australian source waters. The saxitoxins were the only metabolites shown to be non-biodegradable in Myponga Reservoir water, while microcystin-LR (MCLR) and geosmin were biodegradable in this water source. Likewise, cylindrospermopsin (CYN) was shown to be biodegradable in River Murray water. The order of ease of biodegradability followed the trend: MCLR > CYN > geosmin > saxitoxins. Biodegradation of the metabolites was affected by temperature and seasonal variations with more rapid degradation at 24 °C and during autumn compared with 14 °C and during winter. A microcystin-degrading bacterium was isolated and shown to degrade four microcystin variants within 4 h. This bacterium, designated as TT25, was shown to be 99% similar to a Sphingopyxis sp. based on a 16S rRNA gene fragment. Isolate TT25 was shown to contain a homologue of the mlrA gene; the sequence of which was 99% similar to that of a previously reported microcystin-degrader. Furthermore, isolate TT25 could degrade the microcystins in the presence of copper sulphate (0.5 mg L⁻¹ as Cu²⁺) which is advantageous for water authorities dosing such algicides into water bodies to control cyanobacterial blooms.     

The effects of dredging and reclamation on metal levels in water and sediments from an estuarine environment off Trinidad, West Indies

The levels of the metals Fe, Cr, Mn, Ni, Pb, Cu and Cd in marine sediments and sea-water were affected differently by dredging and reclamation activities carried out in a shallow coastal bay area. A two way ANOVA showed that the Mn, Ni, Pb and Cd sediment levels in the area sampled during the dredging period were significantly different (p=0.05) from the levels outside the dredging period. The levels obtained at stations along the paths of the undercurrents in the area showed similar variations to the stations close to where the currents originated for most of the metals monitored. This has been attributed to the translocation of loose dredged sediment by current action. The ANOVA also showed that the Ni and Pb sea-water levels obtained within the dredigng period were significantly different (p=0.05) from the levels obtained outside the dredging period. Marked increases in sea-water levels of Cu, Pb, and Ni occurred subsequent to dredging, apparently as a result of oxidative remobilisation of these metals in fill dumped on a reclaimed site in the vicinity. A comparison of the means of both sediment and sea-water levels within and outside the dredging period showed that the Mn sediment and Fe and Cu sea-water means were lower within the dredging period. Only Cd showed no significant difference in sediment levels between sites while CU and Cd showed no significant differences in sea-water levels between sites. Only Ni sediment levels showed a significant site-date interaction.     

厕所污水回用脱色方法及机理研究

采用投加粉末活性炭对经膜生物反应器处理的厕所回用水(膜出水)进行脱色.对厕所回用水中色度物质的成分及分子量分布,对选定高效适用的活性炭及活性炭对厕所回用水中色度物质的去除机理进行了探讨.试验结果表明,使膜出水显色的物质是一类在紫外区有明显吸收或有特征吸收峰的有机物,且大部分物质分子量分布在6～60 KD的范围内.在选定有高效脱色效果的活性炭时,要综合考虑活性炭的亚甲基蓝吸附值和焦糖脱色率2个指标,其中焦糖脱色率有着更重要的意义.厕所回用水脱色是对其各个分子量区间颜色物质去除效果的总和.     

Hepatic nodular alterations in wild fish from a hyper-eutrophic freshwater system with cyanobacterial blooms: a species and seasonal comparison

Environmental Science and Pollution Research - This paper reports on the seasonal and species comparison of hepatic nodular alterations in two indicator fish species from the hyper-eutrophic...     

厕所污水回用脱色方法及机理研究

采用投加粉末活性炭对经膜生物反应器处理的厕所回用水（膜出水）进行脱色.对厕所回用水中色度物质的成分及分子量分布,对选定高效适用的活性炭及活性炭对厕所回用水中色度物质的去除机理进行了探讨.试验结果表明,使膜出水显色的物质是一类在紫外区有明显吸收或有特征吸收峰的有机物,且大部分物质分子量分布在6～60 KD的范围内.在选定有高效脱色效果的活性炭时,要综合考虑活性炭的亚甲基蓝吸附值和焦糖脱色率2个指标,其中焦糖脱色率有着更重要的意义.厕所回用水脱色是对其各个分子量区间颜色物质去除效果的总和.     

Potential control of toxic cyanobacteria blooms with Moroccan seaweed extracts

Environmental Science and Pollution Research - Marine macroalgae are a promising source of diverse bioactive compounds with applications in the biocontrol of harmful cyanobacteria blooms...     

河流水环境中的非突发性水质风险模型研究

把影响水质模型的随机因素看成一个具有零均值的维纳过程，建立一个研究非突发性水质风险的随机微分动态模型，并对该维纳过程强度进行了估值。研究表明，水环境中的随机因素是引起非突发性风险的一个重要原因。     

A pilot application of recycled discarded RO membranes for low strength gray water reclamation

Environmental Science and Pollution Research - Reuse of recycled RO membranes after oxidative treatment as ultrafiltration membranes promise to bring membrane filtration at par with conventional...     

蓝藻腐烂速度及其对藻水分离水质的影响研究

为了探明湖泊蓝藻在腐烂与藻水分离过程中污染物的释放及去除规律,研究了3种温度下蓝藻腐烂过程中叶绿素a衰减与污染物释放过程,以及混凝沉淀藻水分离工艺尾水水质。结果表明,蓝藻叶绿素a浓度在35℃下培养60h快速下降78.1%,30℃下培养84h下降68.0%,25℃下培养180h下降67.0%,叶绿素a降解衰减过程符合一级反应动力学,25、30、35℃的反应速率常数分别为0.006、0.011、0.027h-1。35℃时,蓝藻污染物24h内快速释放,溶解性总有机碳(DOC)、COD、总溶解性氮(TDN)、总溶解性磷(TDP)平均释放速率分别为8.83、35.25、1.00、0.104mg/(g·h)。30℃时,0～48h污染物释放速度稍慢,之后加快,在84h时接近最大释放量,DOC、COD、TDN、TDP平均释放速率分别为2.61、10.53、0.26、0.027mg/(g·h)。25℃时,污染物释放表现出明显的3个阶段,第1阶段(0～48h)为小幅释放期,释放量占总释放量的10%～30%;第2阶段(48～120h)为平台期,污染物鲜有释放;第3阶段(120～180h)为快速释放期,释放量...