电化学氧化杀灭水库原水中藻类的研究

由Ti/RuO2棒为阳极、不锈钢管为阴极组成电氧化管式反应装置,对电氧化杀灭水库含藻原水中的藻类进行了研究。结果显示:处理累积停留时间20 min后,叶绿素a去除率达100%,对浓缩10倍水样,藻毒素MCLR的去除率达98%以上。细胞的死亡及胞内物质的损失,导致溶液DOC值从32 mg/L上升至50 mg/L,但在电氧化作用下,可下降至12 mg/L。氧化降解产物使溶液UV254值上升,从0.09 cm-1上升至0.14 cm-1,溶液UV410值没有太大变化。处理过程中pH值从8.4迅速下降至7.4后,基本维持稳定,电导率以21μS/(cm.min)速率呈线性下降趋势,溶液离子浓度改变较大。     

Sensitivity analysis of the two dimensional application of the Generic Ecological Model (GEM) to algal bloom prediction in the North Sea

Harmful algae can cause damage to co-existing organisms, tourism and farmers. Accurate predictions of algal future composition and abundance as well as when and where algal blooms may occur could help early warning and mitigating. The Generic Ecological Model is an instrument that can be applied to any water system (fresh, transitional or coastal) to calculate the primary production, chlorophyll-a concentration and phytoplankton species composition. It consists of physical, chemical and ecological model components which are coupled together to build one generic and flexible modelling tool. In this paper the model has been analyzed to assess sensitivity of the simulated chlorophyll-a concentration to a subset of ecologically significant input factors. Only a small number of approaches could be considered as suitable for several reasons including the model complexity, engagement of numerous interacting parameters and relatively long time of a single simulation. Thus, sensitivity analysis has been carried out with the use of the Morris method and later enriched by the computation of the correlation ratios of the selected parameters on the model response at more than a few locations in the modelled area. The obtained results are in agreement with expert knowledge of the ecological processes in the North Sea and correspond well with local characteristics.     

我国淡水藻华长期变动特征综合分析

水体富营养化与淡水藻华（水华）是全球普遍现象,我国是一个高氮磷投入的国家,在人类活动和全球气候变化背景条件下,河流湖库富营养化问题日益突出。文章收集了近30年来我国水华事件的相关文献资料,基于综合研究和统计学分析,回顾性评估了我国水华发生的基本特征、变动规律和成因。数据表明,自上世纪80年代以来,水华发生频率从上世纪80年代每年1～2次上升到2000年以后的每年近10次（不完全统计）,总体呈现上升趋势;水华从湖泊向河流库区扩展,从点到面蔓延,且主要集中在人口密集、污染严重的长江中下游地区和东部沿海地区;在我国化肥施用、畜禽养殖、电站大坝建设等人类活动以及气候变暖的叠加影响下,河流湖库的氮磷浓度上升、氮磷比值下降,水体水化学和生态环境的长期变动加大了水华发生的风险。文章认为,在流域海域综合管理框架下进行氮磷污染的联合控制,以及多学科交叉开展特定水体的水华过程和机理研究是今后藻华防控的根本要求。     

程海冬季水华暴发期间氮、磷营养元素的形态与分布

氮、磷营养元素是湖泊生态系统中极其重要的生态因子,它们以不同形态存在于湖泊水体中,表现出不同的地球化学行为和生态效应,从而支配着湖泊生态系统的生产力水平和湖泊富营养化进程。通过设置3个断面9个采样站14个采样点,研究了程海湖水体中氮、磷营养元素的形态与分布,结果表明：2009年11月23日—2010年2月20日,以铜绿微囊藻（Microcystis aeruginosa Kutz.）为主的程海冬季水华暴发期间,总氮质量浓度0.540~3.906 mg.L-1,平均0.836 mg.L-1;总磷质量浓度0.036~0.166 mg.L-1,平均0.061 mg.L-1。其中,溶解态氮、溶解态磷分别为61.7%和50.8%。溶解态氮以有机氮为主,溶解态磷则以无机磷为主。水华期间生物可直接利用氮质量浓度0.118 mg.L-1;生物可直接利用磷质量浓度0.021 mg.L-1,分别占总氮、总磷质量浓度的14.1%和34.4%,显示出此特定时期,氮的消耗速度较磷快。氮素、磷素及其赋存形态在程海的时间分布上有不同的节奏;水平分布差异不明显;垂直分布在水表层至亚底层的水柱中差异也不明显,而在湖底层最高。     

Allelopathic inhibition on red tide microalgae Skeletonema costatum by five macroalgal extracts

This study aims to identify effective antialgal allelochemicals from marine macroalgae that inhibit the growth of red tide microalgae. Practically, new algicidal agents were developed to control red tide. The growth inhibitory effects of 5 marine macroalgae Porphyra tenera, Laminaria japonica, Ulva pertusa, Enteromorpha clathrata, and Undaria pinnatifida on Skeletonema costatum were evaluated by adding crude seawater extracts of macroalgal dry tissue into the culture medium containing S. costatum. The half-effective concentrations at 120 h (EC_{50, 120 h}) of the seawater extracts were 0.6, 0.9, 1.0, 1.0, and 4.7 g/L for the five macroalgae above, respectively. E. clathrata, L. japonica and U. pertusa showed strong allelopathic effect on the growth of S. costatum. There have been no previous reports with regard to the allelopathic effects of the former two macroalgae so far. The possible allelochemicals of 21 compounds of the E. clathrata were detected using Gas chromatography-mass spectrometry (GC-MS) analysis. Unsaturated fatty acids, acrylic acid (C₃H₄O₂), and linolenic acid (C₁₈H₃₀O₂) were the most likely allelochemicals in E. clathrata.     

水华对沉积物中氮的转化和去除的影响

湖泊富营养化和水华暴发已经成为突出的环境问题之一,了解水华对湖泊氮素的转化和去除的影响,对于削减湖泊氮负荷至关重要.本文研究了水华对沉积物中氮转化和氮转化相关功能基因的影响,并采用结构方程模型分析了水华影响湖泊中氮转化和去除的途径.结果表明,与厌氧氨氧化相比,反硝化作用是太湖沉积物氮削减的主要途径,对沉积物中总溶解性氮去除率的解释度为42. 3%.水华可以直接造成沉积物中TDN和TOC量的增加,提高厌氧氨氧化菌、nir S和nir K的基因丰度,并且间接提高沉积物中氨氮和硝酸盐的浓度,通过增强厌氧氨氧化和反硝化过程加速沉积物中氮的去除.     

沉降除藻协同沉积物覆盖对藻华水体甲烷释放的影响

本研究以藻华水体甲烷释放为对象,利用模拟柱培养实验,探究了沉降除藻和沉积物覆盖复合技术对富营养化甲烷释放的影响.结果表明,沉降除藻结合沉积物覆盖处理可有效改善水环境,实现对甲烷释放的控制,但不同覆盖材料的效果存在差异;活性炭效果要优于土壤和沸石.相比于对照体系水体溶解氧(DO)2. 5 mg·L-1和氧化还原电位(ORP)100 m V,沉积物界面ORP -125 m V,沉降除藻协同活性炭覆盖体系中水体DO和ORP分别升高至3. 1 mg·L-1和174 m V,沉积物界面ORP逆转为168 m V,实验期间甲烷释放量相对于对照组减少90. 2%.研究结果在富营养水体甲烷减排方面具有指导性意义.     

太湖和巢湖夏季蓝藻水华期间产毒微囊藻和非产毒微囊藻种群丰度的空间分布

应用荧光定量PCR技术对蓝藻水华暴发期间太湖和巢湖水体中产毒微囊藻和总微囊藻种群丰度的空间分布进行了研究.分别以微囊藻毒素合成基因基因家族成员mcyD和小核糖体16S rDNA序列构建定量PCR标准曲线,研究产毒微囊藻和总微囊藻种群丰度.结果表明:太湖和巢湖微囊藻种群由产毒微囊藻和非产毒微囊藻组成;蓝藻水华暴发期间,微囊藻种群组成及其丰度分布具有明显的空间差异性:太湖产毒微囊藻种群丰度为9.89×104～4.51×106 copies mL-1,产毒微囊藻占总微囊藻种群的比例为20.5%～38.1%;巢湖产毒微囊藻种群丰度为4.12×104～5.44×106 copies mL-1,其占总微囊藻种群的比例为8.4%～96.6%.总的来说,富营养化严重的湖区总微囊藻和产毒微囊藻种群丰度较高,产毒微囊藻占总微囊藻种群的比例也较高.图7表3参29     

陆生植物化感作用的抑藻研究进展

有效控制水华,治理富营养化水体是目前环境领域的研究热点和前沿。所谓化感物质,就是由植物、细菌、病毒和真菌所产生的二次代谢产物。利用水生植物的化感作用或化感物质抑制水体中藻类的爆发被认为是一种高效、低毒、环境亲合性好的方法而备受关注。然而,对于陆生植物应用于抑制藻类生长的研究却较少。文章在对化感作用的概念的演化、各种生物对藻类化感抑制作用、化感物质抑藻机理等方面进行了较系统的论述,总结了近年来国内外学者对于陆生植物化感作用抑藻的研究进展。文章认为相对于水生植物在抑藻方面的局限性,陆生植物的优势体现在对水生生态系统影响明显（化感作用明显）、所含抑藻化感物质种类丰富、不易受水生生态环境影响等方面,并对今后陆生植物抑藻技术的研究方向进行了展望,陆生植物中尤其是菊科植物化感抑藻应用前景广阔。最后指出,陆生植物的化感抑藻作用研究还存在进一步探索和改进化感物质的提取和鉴定方法、抑藻作用机理的研究、应用实际水体时的生态安全性等方面的问题。     

Programmed cell death induced by modified clay in controlling Prorocentrum donghaiense bloom

Modified clay (MC), an effective material used for the emergency elimination of algal blooms, can rapidly reduce the biomass of harmful algal blooms (HABs) via flocculation. After that, MC can still control bloom population through indirect effects such as oxidative stress, which was initially proposed to be related to programmed cell death (PCD) at molecular level. To further study the MC induced cell death in residual bloom organisms, especially identifying PCD process, we studied the physiological state of the residual Prorocentrum donghaiense. The experimental results showed that flocculation changed the physiological state of the residual cells, as evidenced by growth inhibition and increased reactive oxygen species production. Moreover, this research provides biochemical and ultrastructural evidence showing that MC induces PCD in P. donghaiense. Nuclear changes were observed, and increased caspase-like activity, externalization of phosphatidylserine and DNA fragmentation were detected in MC-treated groups and quantified. And the mitochondrial apoptosis pathway was activated in both MC-treated groups. Besides, the features of MC-induced PCD in a unicellular organism were summarized and its concentration dependent manner was proved. All our preliminary results elucidate the mechanism through which MC can further control HABs by inducing PCD and suggest a promising application of PCD in bloom control.