不同季节温升条件下余氯对桡足类的毒性

为探明桡足类对滨海电厂冷却水中余氯的忍受能力,在各季节于室内对采自乐清湾的12种桡足类进行30 min不同升温幅度(△T)(0、4.0、8.0、12.0℃)下的余氯胁迫,观察桡足类在24h后的死亡率,用概率单位法计算其余氯半致死浓度(Median lethal concentration,LC50).结果表明各季节桡足类余氯LC50随△T增大而显著降低(P＜0.001),且.多数种类呈显著线性回归关系(P＜0.05).对于哲水蚤目桡足类,余氯LC50随其粒径增大而升高.同一种桡足类在相同△T下,随适应水温升高,余氯LC50显著降低(P＜0.01).亚热带海区夏季自然水温较高,冷却系统轻微的升温即可加剧余氯对其的毒性.若以LC50×0.5来确定桡足类余氯安全浓度,则春、秋、冬季暴露时间≤30 min、△T≤12.0℃时,其余氯安全浓度分别为0.21-0.86 mg/L、0.26-0.86 mg/L、0.32-4.55 mg/L;夏季暴露时间≤30 min、△T≤8.0℃时,其余氯安全浓度为0.15-0.41 mg/L.当前电厂加氯浓度偏高对冷却水中桡足类造成较大影响,但排出水中余氯对其影响不大.基于生态安全考虑,根据对余氯较敏感的小型桡足类在不同季节下的余氯安全浓度,建议亚热带滨海电厂夏季余氯排放浓度不超过0.15 mg/L,其余季节不超过0.20 mg/L.     

滨海电厂冷却水余热和余氯对中华哲水蚤的影响

依据滨海电厂冷却系统的实际运作情况,模拟研究了滨海电厂冷却水余热和余氯对中华哲水蚤的影响.结果表明：中华哲水蚤的热忍受能力随暴露时间延长而降低,随驯化温度升高而升高.驯化温度为16 ℃～27 ℃的中华哲水蚤在持续受到15、30、45 min热冲击及持续升温暴露24和48 h的致死温度分别为29.9 ℃～31.7 ℃、29.4 ℃～31.0 ℃、28.9 ℃～30.3 ℃和26.9 ℃～28.5 ℃、26.4 ℃～28.0 ℃.当驯化温度升高到一定程度后,其热忍受能力不再上升.电厂冷却水中余氯对中华哲水蚤的毒性随驯化温度升高、升温幅度增大及暴露时间延长而增强.     

余氯对河流水体微生物灭活效应的评价

【目的】研究不同余氯浓度和暴露时间对细菌的去除效果,分析不同余氯条件对细胞ATP的影响。【方法】以河水中微生物群落为试验对象,利用流式细胞术(Flow cytometry,FCM)评估不同余氯浓度和暴露时间的灭活效果,检测不同余氯浓度时细胞内(外)ATP的变化情况。【结果】不同余氯浓度和暴露时间对细菌的去除效果产生不同的结果。在余氯浓度2 mg/L情况下,延长氯暴露时间可以增加细菌的去除效果,在余氯浓度≥2 mg/L条件下,较短氯暴露时间就可以灭活90%细菌。高核苷酸细菌(HNA)和低核苷酸细菌(LNA)表现出不同氯耐受能力,且HNA细菌相比LNA细菌较容易受到氯的损伤。细胞内ATP随余氯浓度增加而减少,在高浓度余氯条件下(≥2 mg/L)细胞外ATP才会增加。【结论】微生物活性随着余氯作用的增加而降低,FCM法和ATP检测法可以用于评估加氯消毒对微生物稳定性的影响。     

不同温度下氯对水生生物的毒性及制订渔业水质标准的探讨

研究氯对鱼类、蚤类及藻类的急性及亚致死毒性,从急性试验结果看,氯的性随温度的上升而提高。亚致死毒性研究了氯对大型蚤的生殖,白鲢幼鱼的鳃组织学,血液学的变化,白鲢幼鱼的迥避反应及对鲤鱼吸收的影响等,结果说明,氯对水生生物的亚致死死效应不尽相同,不同的生物种,不同的生理指标,氯的亚致死效率与温度的关系也不同,反映出这种毒性效应的复杂性,两者之间并没有固定的相关关系。在亚致死效应中大型蚤的生殖及白链的血液指标对氯最为敏感,据此作者对我国保护水生生物的氯的水质标准提出了一些建议。     

稳定碳同位素在滨海湿地碳生物地球化学循环中的应用

碳作为滨海湿地中重要的生命元素,其生物地球化学循环过程是滨海湿地研究的核心内容之一.稳定同位素技术越来越多地被应用到滨海湿地碳生物地球化学循环过程的研究中,提高了其研究水平,并推动了其研究的进程.本文从有机物质生产、土壤有机质来源、食物链传递、温室气体排放以及可溶性有机碳输出5个方面,综述了滨海湿地碳生物地球化学循环过程的稳定同位素研究进展.通过植物及土壤δ13C值的测定进行有机质的生产机理研究及外源追溯,通过对比各生物种群的δ13C值分析碳在生态系统中的流动过程,通过湿地排放温室气体及可溶性有机碳δ13C值的测定揭示影响碳输出的环境因子.最后,文章总结了当前研究中存在的问题,并对其研究前景进行了展望.     

Effects of mosaic biological soil crusts on vascular plant establishment in a coastal saline land of the Yellow River Delta,China

黄河三角洲滨海盐碱地镶嵌式分布的生物土壤结皮对维管植物建植的影响 滨海盐碱地生物土壤结皮对维管植物影响研究,鲜见报道。本研究旨在探讨黄河三角洲滨海盐碱 地镶嵌式分布的生物土壤结皮是否以及如何影响两种典型草本植物的种子萌发,以深入理解基质异质性对 植物群落动态的影响。通过室内萌发实验,研究裸斑、芦苇(Phragmites australis)、碱蓬(Suaeda glauca) 和柽柳(Tamarix chinensis)生境下发育的生物土壤结皮和无结皮表土对多年生草本植物芦苇和一年生草本植物碱蓬种子的萌发率和平均萌发时间的影响,并从基质理化性质角度探讨其对种子萌发的影响机制。研究结果发现,与无结皮表土相比,生物土壤结皮提高了含水量、养分积累和大部分盐离子浓度,但降低了 土壤pH值。苔藓生物结皮可直接降低土壤pH值和Mg²⁺浓度,间接提高碱蓬种子的萌发率。较低的土壤pH值也间接降低了芦苇种子在其自身生境中的萌发速度。与有植被生长的生境相比,裸斑生境加剧Cl⁻的积累,间接降低了芦苇种子的萌发速度。结果表明,芦苇生境分布的苔藓结皮为碱蓬种子的萌发提供了一个机会窗口。生物土壤结皮类型和生境类型的共同作用可通过影响维管植物种子的萌发和建植,最终影响植物群落结构。     

旅游开发对上海滨海湿地植被的影响

选择上海滨海地区湿地植被为研究对象,采用典型样地与标准样方相结合的调查方法,从属种和生物多样性角度分析不同旅游开发方式对滨海湿地植被的影响。结果如下:(1)根据滨海旅游区水域开放程度,可将开发类型分为封闭式、半封闭式以及开放式3种,不同旅游开发类型对滨海湿地植被影响程度不同;(2)研究区封闭式相比较半封闭式和开放式旅游开发类型,可以提高区域内物种数量,物种数量增加分别增多33和45种,但本地物种所占比例下降,从70%分别下降到26.26%和21.73%;(3)旅游开发封闭性越强,生物多样性越高,封闭式、半封闭式以及开放式旅游开发区域生物多样性Shanno-Winner指数分别为0.92、1.07和1.51,区域内均匀度指数随封闭性增加而有所降低,Shanno-Winner均匀度指数从最高0.71降到最低0.52;(4)滨海湿地植被对不同类型旅游开发响应不同,封闭度越高,区域内植被响应度越强,封闭式、半封闭式以及开放式植被响应指数分别为2.2、2.0和1.8。     

五氯酚在土壤生态系统中的环境行为研究进展

五氯酚在世界范围内广泛使用,在曾经使用过五氯酚的国家和地区的土壤和沉积物可以检测到五氯酚的残留,甚至残留五氯酚可通过食物链危及人类健康。综述了五氯酚在土壤生态系统中的吸附机制与影响因素、化学降解、生物降解及其影响因素、生物富集、生态毒理机理和效应。同时结合目前国内外的研究现状,提出了五氯酚在土壤生态系统中环境行为新的研究方向。     

余氯对小球藻的影响以及损失评估

滨海电厂和液化天然气(LNG)工程排出的余氯水可能对周边海域浮游植物造成不利的影响,从而成为破坏海洋生态系统平衡的重要因素之一。在实验室条件下研究余氯对浮游植物的抑制作用和造成的损失。余氯抑制试验用小球藻(Chlorella sp.)进行,依据工程余氯排放工况,余氯实验浓度设计为0、0.02、0.05、0.10和0.20 mg/L 5个水平;实验温度为27℃,代表夏季;观察时间分别为0、24、48、72和96h。结果表明:高浓度(0.20mg/L)余氯对小球藻生长有抑制作用,最大值出现在48h时,48h之后抑制作用基本维持在同一水平;低浓度(0.02mg/L)对小球藻有促进作用;0.05mg/L组与0.10mg/L组在实验时间24、48h和72h时表现出余氯对小球藻生长抑制作用,在96h时与对照组藻类生长情况差异不显著。采用积分方程计算累计损失率,参考上海LNG工程2009年9月浮游植物细胞丰度值,计算得出工程余氯排放在72h内所造成的藻类理论损失量为1.97×1012个。     

互花米草入侵对滨海湿地生态系统的影响研究进展

滨海湿地受海、陆生态系统的交互影响,是典型的生态脆弱带和敏感区。互花米草是全球海岸带最为成功的外来入侵物种,对滨海湿地生态系统已经产生了重要的影响。本文对已有相关研究进行了系统梳理,揭示了互花米草入侵对滨海湿地生态系统生物地球化学循环(碳循环、氮循环、磷循环及土壤重金属迁移)和入侵地生物群落(微生物、植物和动物)的影响。并在此基础上对今后研究的重点提出了展望: 加强互花米草入侵对滨海湿地生态系统健康影响机制研究;重点关注全球变化背景下互花米草群落与湿地环境互馈耦合;开展长时序定位监测,厘清滨海湿地生态系统对互米草不同入侵阶段的响应差异,以期对互花米草的生态利用和治理提供指导。     

Legionella in industrial cooling towers: monitoring and control strategies

Aims: Legionella contamination of industrial cooling towers has been identified as the cause of sporadic cases and outbreaks of legionellosis among people living nearby. To evaluate and control Legionella contamination in industrial cooling tower water, microbiological monitoring was carried out to determine the effectiveness of the following different disinfection treatments: (i) continuous chlorine concentration of 0·01 ppm and monthly chlorine shock dosing (5 ppm) on a single cooling tower; (ii) continuous chlorine concentration of 0·4 ppm and monthly shock of biocide P3 FERROCID 8580 (BKG Water Solution) on seven towers. Methods and Results: Legionella spp. and total bacterial count (TBC) were determined 3 days before and after each shock dose. Both strategies demonstrated that when chlorine was maintained at low levels, the Legionella count grew to levels above 10⁴ CFU l^?1 while TBC still remained above 10⁸ CFU l^?1. Chlorine shock dosing was able to eliminate bacterial contamination, but only for 10–15 days. Biocide shock dosing was also insufficient to control the problem when the disinfectant concentration was administered at only one point in the plant and at the concentration of 30 ppm. On the other hand, when at a biocide concentration of 30 or 50 ppm was distributed throughout a number of points, depending on the plant hydrodynamics, Legionella counts decreased significantly and often remained below the warning limit. Moreover, the contamination of water entering the plant and the presence of sediment were also important factors for Legionella growth. Conclusions: For effective decontamination of outdoor industrial cooling towers, disinfectants should be distributed in a targeted way, taking into account the possible sources of contamination. Significance and Impact of the Study: The data of the research permitted to modify the procedure of disinfection for better reduce the water and aerosol contamination and consequently the exposure risk.     

Impact assessment of nuclear and thermal power plants on zooplankton in cooling ponds

The current state of assessment of nuclear and thermal power plant toxic effects on zooplankton entrained in the water supply hardware is reviewed. Common research approaches and their inherent problems are considered and particular emphasis is given to specific features of cooling reservoirs and their ecosystems. Complex analysis of zooplankton mortality in various conditions and areas of a cooling reservoir is presented. Our data from field and laboratory studies allow major factors resulting in damage to and mortality of zooplankton to be determined and suggest that, among all plankton species in the cooling reservoir, zooplankton is the most sensitive group to entrainment-induced stress. Our results clearly demonstrate that both field observations and laboratory studies are required to reliably estimate power plant impact on zooplankton and to predict mortality of organisms.     

Bacterial diversity in biofilms formed on condenser tube surfaces in a nuclear power plant

To elucidate the bacterial diversity in biofilms formed on a condenser tube from a nuclear power plant, 16S rRNA gene sequences were examined using a PCR-cloning-sequencing approach. Twelve operational taxonomic units were retrieved in the clone library, and the estimated species richness was low (13.2). Most of the clones (94.7%) were affiliated with α-Proteobacteria; Planctomycetes and γ-Proteobacteria were much rarer. Interestingly, except for one clone belonging to Pseudoalteromonas, most of the sequences displayed sequence similarities <97% of those of the closest type strains. Based on 16S rRNA phylogenetic analysis, most bacteria were assigned to novel taxa above the species level. The low species richness and unusual bacterial composition may be attributable to selective pressure from chlorine in the cooling water. To prevent or control bacterial biofilms in cooling circuits, additional studies of the physiology and ecology of these species will be essential.     

Bacterial diversity in biofilms formed on condenser tube surfaces in a nuclear power plant

To elucidate the bacterial diversity in biofilms formed on a condenser tube from a nuclear power plant, 16S rRNA gene sequences were examined using a PCR-cloning-sequencing approach. Twelve operational taxonomic units were retrieved in the clone library, and the estimated species richness was low (13.2). Most of the clones (94.7%) were affiliated with α-Proteobacteria; Planctomycetes and γ-Proteobacteria were much rarer. Interestingly, except for one clone belonging to Pseudoalteromonas, most of the sequences displayed sequence similarities <97% of those of the closest type strains. Based on 16S rRNA phylogenetic analysis, most bacteria were assigned to novel taxa above the species level. The low species richness and unusual bacterial composition may be attributable to selective pressure from chlorine in the cooling water. To prevent or control bacterial biofilms in cooling circuits, additional studies of the physiology and ecology of these species will be essential.     

Bromoform in the effluents of a nuclear power plant: a potential tracer of coastal water masses

Bromoform (tribromomethane, CHBr₃), one of the trihalomethanes, is a chlorination byproduct in cooling water of power plants and industrial complexes. We used the distribution of bromoform in seawater to monitor the movement of cooling water from the Youngkwang Nuclear Power Plant (YNPP) located on the West Coast of Korea. Bromoform concentrations were highest, 124 g l^–1, in surface water near the outlet of YNPP and decreased linearly with distance from the outlet, mimicking the dissipation of cooling water discharged from the power plant. This byproduct of chlorination is thus a potential tracer of coastal water masses, due to its conservative behavior in the cooling water, low natural background in seawater, and easy analytical detection.     

Impact of thermal discharge from a tropical coastal power plant on phytoplankton

(1) The impact of thermal effluents from coastal power plant located on the east coast of India on phytoplankton was studied by field observations and laboratory experiments. (2) Monthly boat cruises (for 15 months) and laboratory experiments were carried out to study the effects of temperature and chlorine on phytoplankton. (3) Phytoplankton and chlorophyll a decreased during the transit of water from intake point to outfall, while at mixing point the chlorophyll values recovered significantly. (4) Laboratory experiments revealed that decrease in chlorophyll and productivity was largely due to chlorination than due to elevated temperature. (5) Combined temperature and chlorine treatment experiments on phytoplankton showed little synergistic effects. (6) It is concluded that the effect of thermal discharge from the power plant on phytoplankton in the receiving water body is quite localized and phytoplankton distribution and abundance in the coastal waters per se are not affected.     

Comparison of the Efficacy of Free Residual Chlorine and Monochloramine against Biofilms in Model and Full Scale Cooling Towers

The presence of microbial cells on surfaces results in the formation of biofilms, which may also give rise to microbiologically influenced corrosion. Biofilms accumulate on all submerged industrial and environmental surfaces. The efficacy of disinfectants is usually evaluated using planktonic cultures, which often leads to an underestimate of the concentration required to control a biofilm. The aim of this study was to investigate the efficacy of monochloramine on biofilms developed in a cooling tower. The disinfectants selected for the study were commercial formulations recommended for controlling microbial growth in cooling towers. A cooling tower and a laboratory model recirculating water system were used as biofilm reactors. Although previous studies have evaluated the efficacy of free chlorine and monochloramine for controlling biofilm growth, there is a lack of published data concerning the use monochloramine in cooling towers. Stainless steel coupons were inserted in each tower basin for a period of 30 d before removal. Monochloramine and free chlorine were tested under identical conditions on mixed biofilms which had been allowed to grow on coupons. Monochloramine was found to be significantly more effective than free chlorine against cooling tower biofilms.     

Comparison of the efficacy of free residual chlorine and monochloramine against biofilms in model and full scale cooling towers.

The presence of microbial cells on surfaces results in the formation of biofilms, which may also give rise to microbiologically influenced corrosion. Biofilms accumulate on all submerged industrial and environmental surfaces. The efficacy of disinfectants is usually evaluated using planktonic cultures, which often leads to an underestimate of the concentration required to control a biofilm. The aim of this study was to investigate the efficacy of monochloramine on biofilms developed in a cooling tower. The disinfectants selected for the study were commercial formulations recommended for controlling microbial growth in cooling towers. A cooling tower and a laboratory model recirculating water system were used as biofilm reactors. Although previous studies have evaluated the efficacy of free chlorine and monochloramine for controlling biofilm growth, there is a lack of published data concerning the use monochloramine in cooling towers. Stainless steel coupons were inserted in each tower basin for a period of 30 d before removal. Monochloramine and free chlorine were tested under identical conditions on mixed biofilms which had been allowed to grow on coupons. Monochloramine was found to be significantly more effective than free chlorine against cooling tower biofilms.     

炼油厂循环冷却水系统中有害微生物的研究

调查了我国十六个主要炼油厂循环冷却水系统中主要引起污损、腐蚀的有害微生物——形成粘液异养菌、硫酸盐还原菌、铁细菌、真菌的数量及类型;探讨了菌数量和污损危害的相关性,从而提出了炼油厂循环冷却水有害菌控制指标：粘液异养菌<105／ml,硫酸盐还原菌<102／ml,铁细菌<103／ml,真菌相似文献