Long-term joint effect of nutrients and temperature increase on algal growth in Lake Taihu, China

To study how global warming and eutrophication affect water ecosystems, a multiplicative growth Monod model, modified by incorporating the Arrhenius equation, was applied to Lake Taihu to quantitatively study the relationships between algal biomass and both nutrients and temperature using long-term data. To qualitatively assess which factor was a limitation of the improved model, temperature variables were calculated using annual mean air temperature (AT), water temperature (WT), and their average temperature (ST), while substrate variables were calculated using annual mean total nitrogen (TN), total phosphorus (TP), and their weighted aggregate (R), respectively. The nine fitted curves showed that TN and AT were two important factors influencing algal growth; AT limited growth as algal photosynthesis is mainly carried out near the water surface; N leakage of phytoplankton and internal phosphorus load from sediment explains why TN was the best predictor of peak biomass using the Monod model. The fitted results suggest that annual mean algal biomass increased by 0.145 times when annual mean AT increased by 1.0℃. Results also showed that the more eutrophic the lake, the greater the effect AT had on algal growth. Subsequently, the long-term joint effect of annual temperature increase and eutrophication to water ecosystems can be quantitatively assessed and predicted.     

近五年广西茅尾海富营养化成因分析及综合防治对策

利用2006至2010年监测结果和统计资料,评价广西茅尾海近5年富营养化状况,分析富营养化变化与钦州市人口、地区生产总值(GDP)、入海污染物结构、河流入海污染物之间的关系,探讨近年来茅尾海富营养化不断加重的原因,并针对性的提出该海域富营养化的综合防治对策。结果表明近5年茅尾海富营养化程度显逐渐加重的趋势,到2010年茅尾海富营养化程度很严重,河口附近富营养化明显。近5年钦州市人口和经济急剧增长引起的入海污染物不断增加是茅尾海富营养化程度加重的主要原因,尤其以磷酸盐的增加对海湾富营养化及赤潮现象的影响最为显著。因而茅尾海富营养化的综合防治应注重对钦江和茅岭江流域的综合整治以及海湾周边入海污染源的管理,加强污水的脱磷处理等。     

东海赤潮频发区石油烃的季节分布特征

根据2002年4月～2003年3月对东海赤潮高发区表层海水中石油烃污染状况进行的四季现场调查,探讨了该海区石油烃的季节分布特征.结果表明,该海域受到了石油烃的轻度污染,表层海水中石油烃的含量具有明显的时间差异.石油烃的平均浓度夏季最高(0.124 mg/L),春、秋季居中(约0.08 mg/L),冬季最低(0.032 mg/L).并根据调查区域油类污染物排海量及水文情况,对各季节石油烃的水平分布特征进行了初步的分析.     

Sulfur-containing amino acid methionine as the precursor of volatile organic sulfur compounds in algea-induced black bloom

After the application of methionine, a progressive and significant increase occurred in five volatile organic sulfur compounds (VOSCs): methanethiol (MeSH), dimethyl sulfide (DMS), dimethyl disulfide (DMDS), dimethyl trisulfide (DMTS) and dimethyl tetrasulfide (DMTeS). Even in the untreated control without a methionine addition, methionine and its catabolites (VOSCs, mainly DMDS) were found in considerable amounts that were high enough to account for the water’s offensive odor. However, blackening only occurred in two methionine-amended treatments. The VOSCs production was observed to precede black color development, and the reaching of a peak value for total VOSCs was often followed by water blackening. The presence of glucose stimulated the degradation of methionine while postponing the occurrence of the black color and inhibiting the production of VOSCs. In addition, DMDS was found to be the most abundant species produced after the addition of methionine alone, and DMTeS appeared to be the most important compound produced after the addition of methionine+glucose. These results suggest that methionine acted as an important precursor of the VOSCs in lakes suffering from algea-induced black bloom. The existence of glucose may change the transformation pathway of methionine into VOSCs to form larger molecular weight compounds, such as DMTS and DMTeS.     

基于ELCOM-CAEDYM模型的太湖蓝藻水华早期预测探讨

结合太湖蓝藻水华形成的"四阶段理论", 基于澳大利亚西澳大学水研究中心开发的ELCOM-CAEDYM耦合模型框架构建了太湖水华蓝藻生态动力学模型,对蓝藻水华的形成进行模拟,分析了太湖蓝藻水华早期预测的可行性.结果表明:该模型在较长时间尺度上对春季复苏阶段及生长上浮阶段蓝藻水华的形成模拟效果较好,蓝藻生物量模拟值与站点调查值的误差变化范围在1.0%~70.4%,平均误差为28.0%,与MODIS卫星反演值的误差变化范围在3.8%~83.9%,平均误差40.5%;但越冬阶段蓝藻生物量模拟输出值与站点调查值的误差变化范围在3.0%~143.6%,平均误差为40.1%,与MODIS卫星反演值的误差变化范围在9.7%~118.4%,平均误差为48.8%,表明模型对蓝藻越冬过程模拟能力还不强,应在蓝藻越冬机制模拟计算方面进一步改进,以满足蓝藻水华早期预测的需要.     

渤海富营养化现状、机制及其与赤潮的时空耦合性

通过对历年调查与监测数据的整理,从污染物源强、渤海富营养化状况、赤潮发生的时空分布三个角度,分析了渤海近岸海域富营养化的"压力—状态—响应"耦合作用机制。根据文献及调查资料研究渤海营养要素的来源及通量,指出渤海污染物主要来自于陆源输入,并且以河流携带的营养盐输入为主。在对渤海近岸海域历年营养盐含量及富营养化水平分析的基础上,结合赤潮发生的时空变化特征,就富营养化对渤海赤潮的诱导作用与耦合关系进行初步讨论。     

蓝藻暴发对巢湖表层沉积物氮磷及形态分布的影响

以巢湖表层沉积物及上覆水体为对象,于蓝藻暴发前(4月)和蓝藻暴发期(7月)采集水样及沉积物样品,分析了氮磷及其形态赋存特征,并探讨了沉积物氮磷及其形态与蓝藻暴发的关系.结果发现,蓝藻暴发时,巢湖表层沉积物总磷减少,总氮增加,同时削弱了磷在空间上分布的异质性.从氮磷形态来看,蓝藻暴发未造成巢湖表层沉积物氮形态(NH4+-N、NO3--N和Org-N)含量和比例的明显波动,但却造成了活性磷(弱吸附态磷和铁铝结合态磷之和)含量及比例的下降,钙结合态磷(Ca-P)以及有机磷(OP)含量及比例增加,生物有效性磷(AAP)的含量的减小.相关性分析表明,上覆水中叶绿素a(Chl-a)的浓度与铁铝结合态磷(Fe/Al-P)以及有机磷(OP)的含量显著相关(P<0.05),却与氮形态(铵态氮,硝态氮和有机氮)相关性不显著.巢湖沉积物磷(Fe/Al-P及AAP)对巢湖水体蓝藻暴发具有促进作用,而氮及其形态对蓝藻暴发作用较弱.     

藻源性湖泛发生过程的季节差异

藻源性湖泛在春季和夏季均有发生,但湖泛发生的完整过程在野外很难被追踪到.本文利用专利装置进行了春季与夏季藻源性湖泛的室内发生模拟,研究了湖泛发生过程中水体视觉和嗅觉两方面特征指标的变化过程.结果表明:湖泛在春季比夏季需要更长的酝酿时间方可发生,且持续时间较短;春季湖泛发生时水体真色度与悬浮固体含量均要高于夏季,且波动更显著;夏季湖泛致臭物质的变化较春季更明显,具有迅速、持久的特点;春季与夏季藻源性湖泛过程均具有嗅觉特征先于视觉效果显现的现象,即呈现先臭后黑的特点.     

鼠李糖脂对硅藻生长的影响及其选择性抑藻作用

以尖刺拟菱形藻[Pseudo-nitzschiapungens(PS0201-01)]、双突角毛藻(ChaetocerosDidymus)、柔弱角毛藻(Chaertocerosdebilis)、旋链角毛藻(Chaetoceroscurvisetus)和新月菱形藻(Nitzschiaclosterium)5种硅藻为研究对象,探讨了铜绿假单胞菌产鼠李糖脂类生物表面活性剂对海洋硅藻生长的影响.结果表明,当鼠李糖脂的浓度从0.5mg/L至10.0mg/L逐渐递增时,对5种硅藻的生长表现出了不同程度的抑制作用.通过各海洋硅藻脂肪酸组成的差异分析了鼠李糖脂对不同硅藻生长抑制作用具有差异的原因.结果表明,这种差异性与各海洋硅藻生物膜的脂肪酸组成不同相关,海洋硅藻的各种多不饱和脂肪酸的含量越低,相对应的96h-EC50值越低,鼠李糖脂对其生长抑制作用越强,反之亦然.进一步探讨了鼠李糖脂抑藻效果与分属不同门类的多种海洋微藻的脂肪酸组成的关系,确证了鼠李糖脂的选择性抑藻作用与不同海洋微藻生物膜的脂肪酸组成不同相关.     

南四湖浮游硅藻季节性演替及其与环境因子的相关性

为研究南水北调东线工程调水对南四湖硅藻藻密度、种群结构变化的影响,于2010年5月—2013年4月在南四湖进行逐月采样,应用NMDS(non-metric multi-dimensional scaling,非度量性多元标度)分析硅藻种群组成的相似性,并通过冗余分析和Pearson相关性分析研究了硅藻种群结构和环境因子间的相关性. 结果表明:①共检出硅藻23属69种,硅藻藻密度在14.3×104~663.2×104 L-1之间,呈明显的季节性变化,表现为冬春季大于夏秋季;②硅藻种群演替呈明显的季节性变化,冬春季主要以冷水种尖针杆藻(冬春季所占比例分别为15.3%、24.0%)为主,夏秋季则以暖水种扭曲小环藻(夏秋季所占比例分别为17.8%、19.1%)为主;③氮磷营养盐水平、pH和表层水温是影响南四湖硅藻种群变化的主要环境因子. 南四湖硅藻种群对于环境因子变化的反应较为灵敏,可作为南四湖水质的潜在指示工具进行长期研究.