九龙江北溪拟多甲藻水华防治与应急处置

2009年初以来,在福建省九龙江北溪的支流和干流连续发生了拟多甲藻(Peridiniopsis penardii)水华。经检测,拟多甲藻水华没有明显的生物毒性,但其所形成的深褐色水色和轻微藻腥味对该流域的龙岩、漳州和厦门三城市的生产和生活是造成了一定的影响。研究结果表明,在甲藻水华的防治与应急处置过程中,必须进一步加强组织体系建设,明确各职能部门职责,并根据不同水域的实际情况和季节变化,采取相应的物理、化学和生物方法予以防治和应急处置。     

Environmental Control and Limnological Impacts of a Large Recurrent Spring Bloom in Lake Washington,USA

A series of statistical analyses were used to identify temporal and spatial patterns in the phytoplankton and nutrient dynamics of Lake Washington, an mesotrophic lake in Washington State (USA). These analyses were based on fortnightly or monthly samples of water temperature, Secchi transparency, ammonium (NH₄), nitrate (NO₃), inorganic phosphorus (IP), total nitrogen (TN), total phosphorus (TP), dissolved oxygen (DO), pH and chlorophyll a (chl a) collected during 1995–2000 from 12 stations. Lake Washington has a very consistent and pronounced annual spring diatom bloom which occurs from March to May. During this bloom, epilimnetic chl a concentrations peak on average at 10 μg/L, which is 3 times higher than chl a concentrations typically seen during summer stratified conditions. The spring bloom on average comprised 62% diatoms, 21% chlorophytes and 8% cyanobacteria. During summer stratification, diatoms comprised 26% of the phytoplankton community, chlorophytes 37% and cyanobacteria 25%. Cryptophytes comprised approximately 8% of the community throughout the year. Overall, 6 phytoplankton genera (i.e., Aulacoseira, Fragilaria, Cryptomonas, Asterionella, Stephanodiscus, and Ankistrodesmus) cumulatively accounted for over 50% of the community. These analyses also suggest that the phytoplankton community strongly influences the seasonality of NO₃, IP, DO, pH and water clarity. According to a MANOVA, seasonal fluctuations explained 40% of the total variability for the major parameters, spatial heterogeneity explained 10% of variability, and the seasonal-spatial interaction explained 10% of variability. Distinctive patterns were identified between offshore and inshore sampling stations. The results of our analyses also suggest that spatial variability was substantial, but much smaller than temporal variability.     

Impact of climate factors on cyanobacterial dynamics and their interactions with water quality in South Taihu Lake,China

Cyanobacterial bloom events in South Taihu Lake cause serious water quality problems and disturb aesthetic view of lake’s environment. In this study, correlations between cyanobacterial blooms and hydro-meteorological factors, including water quality, temperature and precipitation were investigated. Results demonstrated that South Taihu Lake was heavily affected by cyanobacteria and the proliferation of cyanobacteria due to variations in hydro-meteorological factors and water quality conditions. Water quality parameters, including COD, NH₃-N, TN and TP improved significantly since 2008 even at an elevated cyanobacterial bloom situation. Correlation analyses have shown that the development of cyanobacterial density and chlorophyll a concentration was sensitive to a wider temperature variation. The optimum temperature for cyanobacteria was 20°C, while extremely low and high temperatures were found to suppress their growth. Moreover, unusual rainfall patterns were measured during the study period (2003–2009), which showed an adverse impact on cyanobacterial development. Findings from this study suggested that seasonal lake’s water quality monitoring; suitable treatment of cyanobacterial blooms and strict policy implementation can solve the water quality issues in highly eutrophic lakes like Taihu.     

太湖水质的时空分异特征及其与水华的关系

在大量调查数据的基础上,分析了太湖水质的时空分异特征,探讨了太湖不同湖区、不同季节水质差异的原因。研究结果显示：北部的入湖河口区、几个湖湾、湖心区、西南湖区、东部湖区水体的透明度、高锰酸盐指数、氮、磷、叶绿素等富营养化指标差异显著。入湖河口区的高锰酸盐指数和营养盐含量高于南部湖区数倍,也明显高于北部湖湾区,这反映出太湖西北部入湖河道污染对太湖影响显著。不同季节太湖水质指标也差异显著,冬春期(12～次年5月份)水体的氮含量高于夏秋季(6～11月份)近1倍。水质季节性的显著差异进一步说明了外源输入对太湖水质的影响。研究表明太湖水质的时空异质性既受太湖湖泊形态特征本身的影响,也更多受到外源污染的影响,解决太湖的蓝藻水华问题,首先要在太湖的外源污染控制方面取得突破.     

南京玄武湖微囊藻水华种类组成的研究

2005-08～2006-10采集蓝藻水华样品, 通过形态学特征和ITS序列分子标记的方法对南京玄武湖水华的优势种类进行了鉴定. 结果表明,玄武湖水华主要由微囊藻构成, 通过形态特征鉴定主要种类为铜绿微囊藻(M. aeruginosa)、M. novacekii 和惠氏微囊藻(M. wesenbergii). 3种藻的生物量在水华中的相对比例分别为30%～45%、35%～40%和10%～15%. 采用分子标记的方法对２种优势种类进行了分子鉴定. PCR扩增ITS序列并进行测序, 通过基因序列比对和基于ITS序列的系统发生树分析, 进一步确定了优势种类为M. aeruginosa和M. novacekii; 通过检测产毒基因mcyB来确认2株优势微囊藻的产毒特性, PCR扩增结果均出现了大约为780 bp的特异性片段, 表明这2种藻均为产毒种. 对水华提取物的高效液相色谱(HPLC)测定表明, 玄武湖水华中微囊藻毒素的种类主要是MC-LR和MC-RR.     

东海春季赤潮前后沉积物-海水界面营养盐交换速率的研究

应用实验室培养法现场研究了3～5月东海硅藻赤潮发生前后10个站位的营养盐在沉积物-海水界面的交换,并应用连续函数拟合法计算了营养盐的界面交换速率.结果显示,NO^-₃-N在赤潮前向沉积物中汇聚［-1.33～－0.68 mmol/(m²·d)］,赤潮后却基本由沉积物向海水中释放［－0.69～0.82 mmol/(m²·d)］.NH⁺₄-N在赤潮前后大都从沉积物中释放［－0.65～1.46 mmol/(m²·d)］,赤潮后释放速率小于赤潮前.NO^-₂-N赤潮前后除Zc17站外都向沉积物中汇聚［－0.09～0.05 mmol/(m²·d)］,赤潮后汇聚速率稍高.SiO^2-₃-Si在所有站位都由沉积物向海水释放［0.85～9.23 mmol/(m²·d)］,其赤潮后速率高于赤潮前.PO^3-₄-P在赤潮前向沉积物中汇聚［－0.06～－0.01 mmol/(m²·d)］,在赤潮后却由沉积物向海水中释放［0～1.26 mmol/(m²·d)］.NO^-₃-N和PO^3-₄-P向东海近海沉积物的汇聚在春季不利于硅藻赤潮的暴发,但其在硅藻赤潮暴发后从沉积物的大量释放为后面紧接的大面积甲藻赤潮的暴发提供了重要的营养物质补充.     

多源信息融合技术在内陆湖库水华预警中的研究进展与展望

面对水体富营养化愈来愈严重，水华爆发越来越频繁的严峻形式；为减少水华发生频率及由此造成的损失，开展水华预警已成当务之急。水华爆发是水体中营养盐的累积、气候条件与水力条件等众多因素非线性共同作用的产物；为此，有必要在众多水华影响因素的动态监测信息的融合基础上，寻求水华爆发与这些影响因素间的影射关系，这就需要信息融合技术。通过归纳总结多源信息融合技术在内陆湖库水华预警中应用的研究进展，结合目前我国水华预警的具体需求，提出建立基于多源信息融合技术的水华预警决策支持系统的研究前景与初步设想。信息融合技术为水华预警提供了一个良好的平台，它将与水华相关的不同信息源（水文、气象、水环境质量与环境遥感）所提供的局部不完整的观测信息加以集成与互补，消除多源信息之间存在的冗余和矛盾，形成对水华爆发环境相对完整的感知与描述；从而提高水华预警与应急响应决策的效率，提高预警信息的时间与空间分辨率，扩展信息的时空监测范围。     

大亚湾日本星杆藻种群动态及其与环境因子的关系

研究了1997～1998年及1999和2000年春季大亚湾日本星杆藻(Asterionella japonica)种群动态及其与环境因子之间的关系.日本星杆藻是大亚湾浮游植物常见优势种类,可在全年温度范围(14～32.8℃)内形成数量高峰,并发生水华.日本星杆藻在1998年和2000年春季不常出现,但1999年春丰富的营养盐含量及它们之间合适的比值、多变的水温、稳定的盐度和晴朗的天气使日本星杆藻迅速生长,并发生了水华,最高细胞密度达5255cells/mL.水华消耗了大量的营养,水华期间DIN、DIP和Dsi分别下降了76.0%、69.7%和58.8%,而且营养元素的消耗特别是DIN的耗尽是水华消退的重要原因,而桡足类等浮游动物摄食也是水华消退的原因之一.     

2004年夏季太湖梅梁湾席状漂浮水华风力漂移入湾量计算

太湖北部重度水华暴发时,在夏季盛行风推动下,漂浮的席状水华可由大太湖漂移进入位于太湖北部的梅梁湾,使湾内的水华加剧.本文通过室内风箱水槽实验和野外观测,对水华的风力漂移作了定量研究,建立了风速与水华漂移速度的指数相关方程.并据此对2004年夏季太湖北部发生席状水华的6d分别计算了水华风力漂移入湾量.6d中,只有2004-07-31水华漂移是由湾内向大太湖输出,且量很小,只有0.05 km²;其余5d水华漂移进入梅梁湾的面积占整个梅梁湾面积的3.7%～13.3%,进入量最大的是2004-06-11,达17.4km²,最少的是2004-07-30,为4.8 km².     

Growth characteristics of algae during early stages of phytoplankton bloom in Lake Taihu, China

Three treatments, sediment plus lake water (S+W), sterilized sediment plus lake water (SS+W), and sediment plus filtered lake water (S+FW), were recruited to investigate the growth characteristics of algae during pre-bloom and the importance of algal inocula in the water column and sediment. The results showed that in the water column, biomass of all algae increased in all treatments when recruitment was initiated, whereas this tendency differed among treatments with further increment of temperature. The process of algal growth consisted of two stages: Stage I, the onset of recruitment and Stage II, the subsequent growth of algae. Compared with S+W, in Stage I, SS+W significantly increased the biomass of cyanophytes by 178.70%, and decreased the biomass of non-cyanophytes by 43.40%; In Stage II, SS+W notably stimulated the growth of all algae, thus incurring the occurrence of phytoplankton bloom. Further analyses revealed that both metabolic activity and photochemical activity of algae were enhanced in SS+W, which resulted from the releasing of nutrients from sediment. These results suggest that algal growth in Stage II and algal inocula in the water column can be important factors for the formation of phytoplankton bloom. In addition, possible mechanisms promoting algal recruitment and subsequent growth of algae were explored.