营养盐输入对太湖水体中磷形态转化及藻类生长的影响

外源营养盐输入会对湖泊水体中磷的形态转化及藻类生长产生影响.为研究其影响规律,于春季选取太湖梅梁湾水体为研究对象,以KNO3和K2HPO4添加系列氮磷负荷,在试验过程中对各形态磷的浓度、藻类生物量(Chl-a)和碱性磷酸酶活性(APA)进行同步分析测定.结果表明,春季太湖梅梁湾水体中浮游植物的生长主要受到磷限制,加氮对其生长没有明显的促进作用.加磷至SRP=0.015 mg·L-1的水体中浮游植物生长情况最好,叶绿素a的含量和生长速率(μ)最大.添加硝酸盐能显著促进APA的增长,提高水生生物对磷的吸收利用能力,加快磷循环的速率;磷酸盐对APA则具有活性诱导-抑制机制,当水体中磷酸盐浓度在一定范围内(PO3-4-P≤0.025 mg·L-1)时,酶活性有显著提高.对水体中磷的循环转化过程和碱性磷酸酶的活性诱导-抑制机制的研究结果有助于揭示藻类生长过程中营养盐的补偿途径,为深入揭示藻类暴发机制提供理论基础.     

环境因子对香溪河春季藻类生长影响的模拟实验

2010年3~5月间,分3批次采集了香溪河水样,以水体营养盐浓度、水温、光强和流速为环境因子,以Chla比增长率为评价指标,在室内进行L9(34)的正交藻类培养实验,研究了环境因子对春季优势硅藻生长的影响.结果表明,在实验所设定的水平范围内,水体营养盐浓度总氮(TN)为3.5mg/L、总磷(TP)为0.3mg/L,水温20℃,光强为4700lx以及流速为0.1m/s时,最适宜藻类生长.4因子对藻类生长影响大小依次为光强、流速、水温、营养盐浓度.流速在0.05m/s和0.1m/s的情况下,藻类生长率明显高于静水.当TN<1.5mg/L,TP<0.1mg/L时,增加TN、TP浓度可显著促进藻类生长;当TN、TP浓度分别达到3.5mg/L、0.3mg/L时, N、P浓度的增加对藻类生长影响甚微.     

三峡水库支流回水区富营养化时空分布特征

为了解三峡水库175m水位蓄水后库区支流回水区富营养化现状,探索支流回水区富营养化时空变化规律,在三峡库区支流回水区开展了富营养化普查和监测。结果表明,库区支流总磷浓度为0.035~0.65 mg/L,平均浓度为0.157 mg/L,总氮浓度为0.681~5.690 mg/L,平均浓度为2.037mg/L,远远高于湖库水体出现富营养化的总磷和总氮临界浓度0.02、0.2 m g/L,库区支流营养盐条件适宜藻类生长。在每年4~9月的春季、盛夏和夏秋之交的非暴雨时段,当气温和光照适宜,支流回水核心区富营养化现象明显,出现藻类"疯长"的水华现象,但受气温变化影响明显,库区的富营养化现象仍是间歇的,局部的。     

风浪对太湖水体中胶体态营养盐和浮游植物的影响

为了解不同风浪条件下太湖水中胶体态营养盐和浮游植物含量的特征, 选择不同风速情况进行现场观测和采样, 用切向流超滤法获取胶体, 测定胶体态有机碳、氮、磷及其他形态营养盐含量. 同时收集浮游植物样品, 测定其密度和生物量. 结果表明, 在风速小于4m/s时胶体氮(CN)和胶体磷(CP)含量随风速变大而升高, 而在风速大于4 m/s时其含量不再升高, 甚至略有降低; 叶绿素a(Chl-a)、浮游植物密度、蓝藻密度和蓝藻生物量均在风速小于4m/s时随风速增大而升高, 在风速大于4 m/s时随风速增大而降低, 说明小风浪有利于蓝藻生长或漂浮, 而大风浪对其生长或漂浮不利. CN和CP含量与浮游藻类含量呈显著正相关, 表明在藻类生长旺盛的夏季, 太湖水中胶体氮、磷的主要来源为藻类产物.     

营养条件对污水中小球藻生长及产能效应的影响

以过滤的富营养化的鱼塘废水为培养液,添加外源的碳、氮、磷元素,考察污水中不同的外源无机碳浓度、总氮浓度、总磷浓度对小球藻(Chlorella vulgaris)的生长、油脂含量和烃类含量的影响。在25℃、光照强度为4 500 Lux、光暗比为12L:12D的条件下培养10 d。单因子方差分析和多重比较结果表明:(1)以Na2CO3做碳源,小球藻生物量和烃类含量在外源无机碳浓度为6 mg/L时最高,油脂含量在外源无机碳浓度为12 mg/L最高。(2)以KNO3做氮源,小球藻生物量在总氮浓度为25 mg/L时最高,油脂含量在总氮浓度为15 mg/L时最高,烃含量在总氮浓度为20 mg/L时最高。(3)以KH2PO4做磷源,小球藻生物量和烃类含量在总磷浓度为2 mg/L时最高,油脂含量在总磷浓度为1.5 mg/L时最高。     

水体的营养水平对苦草(Vallisneria atans)生长的影响

在室外控制条件下,以太湖梅梁湾水体现状营养水平(ρ(TN)为5 mg/L和ρ(TP)为0.2 mg/L)为依据,研究营养盐含量升高对苦草生长的影响.结果表明:①在满足光补偿点及无种间竞争等的条件下,苦草在营养水平为ρ(TN)＞10 mg/L和ρ(TP)＞0.4 mg/L的水中也能成活.②随着营养盐含量的升高,苦草生物量的增长率逐渐降低,当水中ρ(TN)达到10 mg/L和ρ(TP)达到0.4 mg/L时,苦草的生物量开始减少;营养盐含量升高对苦草叶片特征的影响不明显,而苦草根状茎的生物量却随着营养盐含量的升高而逐渐减少,当水体营养水平达到ρ(TN)为10 mg/L和ρ(TP)为0.4 mg/L时,除叶片长度外,苦草的其他形态指标值均显著下降.③在梅梁湾水体现状营养水平的基础上,当水中磷含量增加1倍时对苦草生长造成的抑制作用大于氮含量增加1倍时;当二者均增加时,对植物生长造成的抑制作用显著增加.     

氮磷比对水华蓝藻优势形成的影响

通过批量培养实验研究了不同磷水平下N/P比对铜绿微囊藻(蓝藻)和斜生栅藻(绿藻)生长速率的影响,并在太湖蓝藻水华暴发期间,监测了梅梁湾和湖心区水体叶绿素a浓度和氮磷营养盐结构变化,以探讨N/P比对蓝藻优势形成的影响.结果表明, N/P比对铜绿微囊藻和斜生栅藻生长的影响并不表现在一个确定值上,而与水体氮磷的绝对浓度有关,在0.02mg/L磷浓度下,铜绿微囊藻和斜生栅藻在N/P比为4:1~32:1范围内生长速率均较低(0.067~0.074,0.018~0.022d-1),说明受到营养盐的限制;当磷浓度达到0.20mg/L时, 铜绿微囊藻在N/P比为32:1时生长速率达到最大值(0.240d-1),斜生栅藻在N/P比为64:1时生长速率达到最大值(0.380 d-1);而在磷浓度升高到2.00mg/L时,不同N/P比下铜绿微囊藻和斜生栅藻均达到最大生长速率(0.24~0.25, 0.378~0.381d-1),说明氮磷浓度均比较充足,N/P比对生长速率已经没影响.可见,氮磷浓度比N/P比对两种藻的生长影响更大.与斜生栅藻相比,铜绿微囊藻对氮磷营养的生理需求和最大生长速率均相对较低,属K策略物种,易在低氮磷浓度下形成优势.梅梁湾在水华暴发期间氮浓度一直远低于水华较轻的湖心区,而磷浓度远高于湖心区,进而导致梅梁湾N/P质量比(低于20:1)在水华期间一直低于湖心区(124:1),低N/P比是蓝藻水华暴发导致氮浓度下降,磷浓度升高的结果.     

太湖附泥藻类生物量空间分布及其与环境营养盐的关系

为了揭示富营养化浅水湖泊附泥藻类空间分布及其与环境营养盐之间的关系,于2015年6月9—15日对太湖进行高密度布点采样,研究了太湖表层沉积物上附泥藻类生物量及表层沉积物和水柱中氮、磷等营养盐含量的空间分布特征及其相互关系.结果表明,太湖附泥藻类生物量(以叶绿素a表征)空间异质性明显,最小值为0.07μg·g-1,最大值为1.66μg·g-1,平均值为0.34μg·g-1.附泥藻类生物量在太湖西北部及东太湖较高,其次是贡湖湾、梅梁湾及东部沿岸,在西南部湖区较低;太湖水体中氮、磷等元素含量也存在明显的空间变化,水体中氮、磷含量在竺山湾、梅粱湾及太湖西部明显高于其它湖区;太湖表层沉积物中总有机碳(TOC)、氮、磷等元素含量空间异质性显著,表层沉积物中总磷及各种形态磷含量的空间分布特征与水体中总氮、总磷分布特征类似,表层沉积物总氮及TOC的含量在太湖西北部(包括竺山湾)、梅梁湾、东部湖区(包括东太湖、胥口湾)较高,在西南部湖心区较低;太湖附泥藻类生物量与水体氮、磷含量、沉积物氮、磷及不同形态磷(Ca-P除外)含量均呈显著正相关关系(r≥0.18,p0.05).由此可见,太湖附泥藻类生物量的空间异质性既受水体氮、磷浓度的影响,也受沉积物氮、磷等营养水平的制约.本研究结果可为进一步研究附泥藻类在太湖生态系统中功能,以及深入探求太湖富营养化治理途径提供一定的理论依据.     

考虑光盐交互作用的湖泊富营养化数学模型

基于水体光学原理,确定了光照衰减系数与透明度之间的定量关系式;基于质量守恒原理,描述了氮磷营养盐与藻类之间的转化关系;耦合光因子和盐因子对藻类生长的驱动机制,建立了考虑光盐交互作用的富营养化数学模型.结合2015年4~7月在眉湖开展的水质监测数据,对模型进行了参数率定与验证.通过正交设计与情景模拟相结合,研究了光盐条件变化对藻类生长的驱动作用.结果表明,建立的富营养化模型能够较好的模拟不同光盐条件下藻类的生长趋势;低光照强度下营养盐浓度增加对藻类生长起到了抑制作用,营养盐浓度增加相同的倍数时TP浓度变化对藻类生长的影响作用要比TN浓度变化对藻类生长的影响作用大;整体上藻类的生长受到光照强度的影响高于营养盐,受到总磷的影响高于总氮,在设置的情境中光照强度、TP和TN浓度分别为89.6klx、0.168mg/L和2.72mg/L时最利于藻类生长.     

水温和营养盐增加对太湖冬、春季节藻类生长的影响

为探讨水温和营养盐增加对冬、春季节太湖藻类生长和群落演替的影响,研究了不同水温(不增温、12.0、14.0、16.0、18.0、20.0℃)和不同营养盐浓度(低、中、高营养盐浓度)下藻类的生长及优势种群变化. 结果表明:藻类∑ρ(Chla)〔蓝藻、绿藻及硅藻中ρ(Chla)总量,下同〕随着水温的升高呈增加趋势,在20.0℃下∑ρ(Chla)为0.19~12.94μg/L,显著高于其他水温试验组(0.01~6.83μg/L);与较低水温(不增温、12.0、14.0℃)相比,较高水温(16.0、18.0、20.0℃)更能显著促进藻类对氮、磷营养盐的吸收利用. 添加营养盐后,硅藻、绿藻ρ(Chla)的日均值分别为0.52~4.07、0.17~0.52μg/L;湖水中∑ρ(Chla)呈增长趋势,并且浮游植物群落结构的优势种由绿藻转变为硅藻,硅藻ρ(Chla)所占比例从试验初始的50%升至75%~98%, 说明营养盐增加可加大硅藻的竞争优势;而绿藻的生长则可能同时受水温和营养盐共同作用的影响,因此太湖冬、春季节藻类的演替同时受到水温和营养盐的影响.      

初夏渤海湾营养盐结构特征及其限制状况分析

根据2016年初夏渤海湾营养盐、叶绿素a和相关水文参数等数据,利用浮游植物吸收营养盐最低阈值和化学计量关系作为判断依据对渤海湾营养盐限制状况进行分析.结果表明：受陆地径流和渤海中部冷水输入的影响,初夏渤海湾在近岸、中部和湾口呈现三个明显的温盐特征海区.溶解无机氮（DIN）和活性硅酸盐（SiO₃^2--Si）受陆源输入影响,呈现近岸高湾口低的特征;DIN平均浓度为（7.67±6.48）μmol/L,SiO₃^2--Si平均浓度为（5.44±3.01）μmol/L,在湾口表层,DIN含量较低仅为（2.21±2.94）μmol/L,其中50%站点含量低于阈值（1μmol/L）,58.3%的站点存在DIN限制.而活性磷酸盐（PO₄^3--P）受陆源输入和浮游植物吸收储存作用等因素影响,呈现西部和曹妃甸外近海高中部较低的分布特征,平均浓度为（0.07±0.07）μmol/L,近岸受陆源氮磷输入总量差异影响,表层存在磷潜在限制比例达100%,而中部表层受浮游植物消耗吸收的影响,PO₄^3--P含量较低,仅为（0.02±0.02）μmol/L （未检出设为0）,其中近74.3%的水样含量低于阈值（0.03μmol/L）,磷限制状况严重.随着渤海湾氮磷营养盐陆源输入总量差距不断扩大,磷限制状况必将会进一步发展.     

春季桑沟湾海域贝类养殖对海水中营养盐的影响研究

根据2011年春季对桑沟湾海域8个监测点的营养盐的变化特征和历史资料的研究,分析了桑沟湾水域溶解性无机氮(DIN)、总氮(TN)、活性磷酸盐(PO34-)和总磷(TP)浓度变化及它们之间的相互关系,估算了贝类养殖的排泄物对海水污染的贡献率。结果表明,溶解性无机氮的平均浓度为0.106 1 mg/L,NO3-N为主要存在形式,占溶解性无机氮平均含量的78.3%,NH3-N、NO2-N分别占溶解性无机氮平均含量的14.2%和7.5%。总氮的平均浓度为0.234 7 mg/L,溶解性无机氮浓度占总氮浓度的45.2%。活性磷酸盐的平均浓度为0.013 3 mg/L,总磷的平均浓度为0.024 78 mg/L。春季桑沟湾贝类养殖对该海域海水磷含量的贡献率比氮的贡献率大,N/P为17.63,营养水平基本属于贫营养。     

氮磷形态与浓度对铜绿微囊藻和斜生栅藻生长的影响

以铜绿微囊藻（Microcystis aeruginosa）和斜生栅藻（Scendesmus obliquus）为研究对象,分别以硝酸钠、氯化铵和尿素为氮源,以磷酸氢二钾、甘油磷酸钠和三磷酸腺苷为磷源,配置不同浓度的氮磷培养基（氮浓度1.00,4.00,8.00mg/L,磷浓度0.20,2.00mg/L）,通过一次性培养实验研究2种藻氮、磷饥饿时对不同形态和不同浓度氮磷的生长响应.结果表明,2种藻对氮、磷的形态和浓度响应均不同,且藻种之间也有明显的响应差异.铜绿微囊藻在3种浓度硝酸钠培养下比生长速率无显著差异,而斜生栅藻的比生长速率在硝酸钠4.00mg/L时达到最高,说明1.00mg/L的硝酸钠已满足铜绿微囊藻对氮的生长需求,斜生栅藻对氮的需求高于铜绿微囊藻.铜绿微囊藻在1.00,4.00mg/L氯化铵和尿素培养下的比生长速率相同,且比生长速率和现存量均高于同浓度硝酸钠培养组,说明相比于硝酸钠,铜绿微囊藻更喜欢利用还原态的氯化铵和尿素.但当氯化铵浓度高达8.00mg/L时,铜绿微囊藻比生长速率低于相同浓度尿素和硝酸钠培养组,也低于低浓度氯化铵培养组,说明高浓度氯化铵不利于铜绿微囊藻的生长.然而,斜生栅藻在8.00mg/L氯化铵培养下比生长速率和现存量与尿素培养时无显著差异,而且均高于硝酸钠培养组,说明斜生栅藻对氯化铵的耐受能力比铜绿微囊藻高.3种形态的磷均能被铜绿微囊藻和斜生栅藻利用,但铜绿微囊藻用高浓度有机磷培养时的现存量更高,斜生栅藻则在高浓度无机磷培养下生长更好,说明铜绿微囊藻比斜生栅藻能更好的利用有机磷,高浓度的无机磷不利于铜绿微囊藻生长.太湖目前铵氮浓度降低显著,水体无机磷占比很低,溶解态有机磷浓度占比较高,这些都更有利于蓝藻形成优势.     

不同营养水平下苦草对附着和浮游藻类的影响

通过室内培养,研究了不同营养盐浓度下苦草对附着藻类和浮游藻类的影响,同时比较了两种藻类对不同营养盐浓度的响应,结果发现附着藻类在中高营养盐浓度下生物量较高而浮游藻类在中低营养盐浓度下生物量较高,虽然两者对营养盐的响应不一致,但其最大量都出现在中高浓度的营养盐状态下。在中低营养盐浓度下(ρTN=0.4～2.5mg/L),苦草促进附着藻类而抑制浮游藻类,即相比于浮游藻类而言,附着藻类对苦草的敏感性较低。在较高营养盐浓度(ρTN=4.5～6.5mg/L)下,苦草对附着藻类产生了极显著的抑制作用,且这种抑制作用随着营养盐浓度的增加而增强,在ρTN=6.5mg/L的处理条件下,苦草对附着藻类的抑制率近80%,但是在此营养盐浓度处理下,苦草对浮游藻类的抑制作用却减弱甚至消失了。     

斜生栅藻对低浓度无机磷去除和生长情况的研究

研究分析了低磷浓度培养条件对斜生栅藻生长情况的影响,以及斜生栅藻对磷的去除效果.结果表明,斜生栅藻在初始细胞浓度为1×105个/mL时,可以在22h内将初始浓度0.02～0.10mg/L的磷全部去除.在初始磷浓度0.02～0.10mg/L范围内,随磷浓度的增加藻体的生长速度增加,且最大生物量也明显增大.研究发现磷浓度对斜生栅藻的形态有重要影响,在外源磷充足的条件下,斜生栅藻多为四聚体,但随着磷浓度的逐渐下降,藻细胞从四聚体,分离为二聚体,最后以单聚体为主要存在形式.     

Influence of phosphorus on Microcystis growth and the changes of other environmental factors

The growth processes of Microcystis aeruginosa （FACHB-41） in simulated Taihu Lake water with different phosphorus concentrations were investigated using laboratory microcosms. The algal biomass increased with the increase of phosphorus concentration when it was lower than 0.445 mg/L, while the dissolved oxygen （DO） and pH increased, dissolved inorganic nitrogen （DIN） and light intensity underwater（I） decreased. Responding to the changes of the “environmental factors”, the cellular carbohydrate and its ratio to cellular protein decreased generally as phosphorus increased. However, when phosphorus concentration was higher than l. 645 mg/L, the biomass, the “environmental factors”, the cellular carbohydrate and its ratio to cellular protein did not change likewise. Since the environmental factors and the physiological and biochemical responses are important factors, the change of environmental factors and cell physiology and biochemistry induced by phosphorus may become the key factors that steer the growth and dominance of Microcystis under certain conditions. To sum up, phosphorus not only stimulate the growth of Microcystis directly by supplying nutrient element, but also has complex interactions with other “environmental factors” and play important roles in the growth processes of Microcystis .     

Characteristics of anoxic phosphors removal in sequence batch reactor

The characteristics of anaerobic phosphorus release and anoxic phosphorus uptake were investigated in sequencing batch reactors using denitrifying phosphorus removing bacteria （DPB） sludge. The lab-scale experiments were accomplished under conditions of various nitrite concentrations （5.5, 9.5, and 15 mg/L） and mixed liquor suspended solids （MLSS） （1844, 3231, and 6730 mg/L）. The results obtained confirmed that nitrite, MLSS, and pH were key factors, which had a significant impact on anaerobic phosphorus release and anoxic phosphorus uptake in the biological phosphorous removal process. The nitrites were able to successfully act as electron acceptors for phosphorous uptake at a limited concentration between 5.5 and 9.5 mg/L. The denitrification and dephosphorous were inhibited when the nitrite concentration reached 15 mg/L. This observation indicated that the nitrite would not inhibit phosphorus uptake before it exceeded a threshold concentration. It was assumed that an increase of MLSS concentration from 1844 mg/L to 6730 mg/L led to the increase of denitrification and anoxic P-uptake rate. On the contrary, the average P-uptake/N denitrifying reduced from 2.10 to 1.57 mg PO4^3--P/mg NO3^--N. Therefore, it could be concluded that increasing MLSS of the DEPHANOX system might shorten the reaction time of phosphorus release and anoxic phosphorus uptake. However, excessive MLSS might reduce the specific denitrifying rate. Meanwhile, a rapid pH increase occurred at the beginning of the anoxic conditions as a result of denitrification and anoxic phosphate uptake. Anaerobic P release rate increased with an increase in pH. Moreover, when pH exceeded a relatively high value of 8.0, the dissolved P concentration decreased in the liquid phase, because of chemical precipitation. This observation suggested that pH should be strictly controlled below 8.0 to avoid chemical precipitation if the biological denitrifying phosphorus removal capability is to be studied accurately.     

Phytoplankton community from Lake Taihu, China, has dissimilar responses to inorganic and organic nutrients

To evaluate the response of phytoplankton from Lake Taihu to di erent types of nutrients, the phytoplankton responses were measured after adding inorganic nitrogen (N) and phosphorus (P) or decomposed algal scum (Microcystis spp.) into the lake water. Both types of nutrients promoted an increase in phytoplankton biomass as determined by chlorophyll a and algal wet weight. The addition of decomposed algal scum resulted in a significantly greater phytoplankton response than the addition of inorganic N and P alone. The dissolved inorganic N and P in the inorganic nutrient treatment were found not limit phytoplankton growth. The higher algal biomass obtained in the treatment with decomposed algal scum indicated the importance of other organic nutrients besides N and P such as trace elements, as well as the importance of the form of N since the levels of ammonia nitrogen (NH4 +-N) from the decomposed algal treatment were actually higher than that of the inorganic N and P addition. Microcystis spp. (Cyanobacteria), Scenedesmus spp. (Chlorophyta) and Synechocystis spp. (Cyanobacteria) were the dominant taxa in the control, inorganic N and P treatment, and the decomposed algal scum treatment, respectively. Microcystis never bloomed in response to both types of nutrient additions indicating that the bloom propagation is not solely related to nutrient additions, but may be related to the absence of selective grazing from zooplankton.     

Controlling cyanobacterial blooms by managing nutrient ratio and limitation in a large hypereutrophic lake: Lake Taihu, China

Excessive nitrogen (N) and phosphorus (P) loading of aquatic ecosystems is a leading cause of eutrophication and harmful algal blooms worldwide, and reducing nutrient levels in water has been a primary management objective. To provide a rational protection strategy and predict future trends of eutrophication in eutrophic lakes, we need to understand the relationships between nutrient ratios and nutrient limitations. We conducted a set of outdoor bioassays at the shore of Lake Taihu. It showed that N only additions induced phytoplankton growth but adding only P did not. Combined N plus P additions promoted higher phytoplankton biomass than N only additions, which suggested that both N and P were deficient for maximum phytoplankton growth in this lake (TN:TP = 18.9). When nutrients are present at less than 7.75-13.95 mg/L TN and 0.41-0.74 mg/L TP, the deficiency of either N or P or both limits the growth of phytoplankton. N limitation then takes place when the TN:TP ratio is less than 21.5-24.7 (TDN:TDP was 34.2-44.3), and P limitation occurs above this. Therefore, according to this ratio, controlling N when N limitation exists and controlling P when P deficiency is present will prevent algal blooms effectively in the short term. But for the long term, a persistent dual nutrient (N and P) management strategy is necessary.