镉胁迫对铜绿微囊藻的抑制作用及营养盐浓度对其的减缓效应

为研究镉胁迫对铜绿微囊藻的生长和生理特征影响,评估氮、磷在减缓镉胁迫中作用,将处于指数生长期的铜绿微囊藻接种于不同的镉胁迫浓度和3种营养盐水平下96 h。结果表明,当镉浓度小于10μmol/L,随着氮、磷浓度增大,藻的生物量、比生长速率、叶绿素a、可溶性蛋白、可溶性糖的浓度和超氧化物歧化酶活性随之增加,然而在镉浓度为10μmol/L时铜绿微囊藻的这些指标含量基本相同,但类胡萝卜素只有在镉浓度为10μmol/L时才会出现明显的降低。     

环境因子对引黄水库水中水华鱼腥藻生长的影响

以济南引黄水库水中分离出的水华鱼腥藻为对象,研究了不同培养温度、光照、pH条件对其生长的影响;在最佳培养温度和光照强度的基础上设计了L9(34)正交试验模拟研究氮磷物质对水华鱼腥藻生长的影响。结果表明水华鱼腥藻的最适生长温度为30℃,光强为6 000lx;氮磷营养盐对藻类生长影响排序为硝酸盐磷酸盐氨氮亚硝酸盐。研究提示磷可能是引黄水库水华鱼腥藻生长限制因子,在夏、秋季及水库氮、磷浓度大幅变化时应预防鱼腥藻水华的发生。     

铁在不同磷源条件下对铜绿微囊藻生长与产毒的影响

针对磷和微量元素铁对藻类生长的共同作用,研究不同磷源下藻细胞生长与产毒过程中磷与铁的共同作用特性。试验选用产毒铜绿微囊藻为藻种,以硝态氮为氮源,分别以磷酸氢二钾(K_2HPO_4)、小分子有机磷甘油磷酸钠(Na Gly)和大分子有机磷卵磷脂(LEC)为磷源,同步考察不同铁离子(Fe~(3+))浓度下藻类的生长与产毒表现。结果表明:K_2HPO_4和NaGly是藻细胞优先利用的磷源,在这两种磷源条件下,藻细胞的生长与产毒均得到促进,藻细胞平均粒径随培养时间保持稳定; LEC不利于藻细胞的生长与产毒,且藻细胞平均粒径波动较大。在对数增长期中,叶绿素a与胞内藻毒素(MC-LR)呈现正相关关系,在培养过程中藻细胞胞内总磷与藻液中总的碱性磷酸酶活性并未显现出相关性。不同磷源下微量元素铁对藻细胞的生长状况影响不同,NaGly与铁的协同作用更有利于藻细胞的生长与产毒。     

泽雅水库藻类群落组成及季节变化特征研究

利用2014年5月至2016年12月的监测成果,对泽雅水库的藻类群落结构和季节变化进行系统分析,结果表明:泽雅水库藻类群落结构涵盖6门30属,以硅藻、隐藻、绿藻为主要种群,常年监测优势种群有针杆藻、隐藻、栅藻、直链藻和小环藻,每年6—9月出现藻类高发现象;藻类数量与水温、水体p H值呈显著正相关,与总氮、总磷的相关性不显著;该水库藻类生长基本不受氮、磷营养盐限制。     

冬季节制闸调控对巢湖水质影响评估

厘清湖泊大型节制闸工程冬季不同调控对湖泊水质时空分布格局变化的影响,对于科学提升湖泊水环境质量、保障供水安全和提高工程综合效益具有重大意义。利用巢湖数字流场平台,以 2020 年冬季巢湖高水位为背景,模拟了巢湖闸稳定泄流、分时段泄流和综合泄流三种调控方案下巢湖总氮、总磷、氨氮和藻类生物量的响应特征和后续效应。结果表明：不同泄流方案可降低巢湖全湖氨氮和西半湖总氮、总磷浓度,但会造成中东部湖区总氮和总磷浓度,以及全湖藻类生物量的上升;稳定泄流方案影响最为明显,该方案下全湖氨氮浓度平均下降 4.13%,藻类生物量平均上升 6.59%。开闸泄流有利于缩减湖体氮、磷、藻的总存量,有利于后期较大水时巢湖总磷、总氮浓度的控制。     

不同氮源对四尾栅藻生长的影响

为探讨四尾栅藻的生长与不同氮源的关系，在铵态氮、硝态氮 和有机氮的不同浓度下分批培养四尾栅藻，并对每组中藻的生长曲线和最大比增长速率进行了分析和比较。结果表明，在实验设定的浓度范围内，四尾栅藻生长所需的最适初始氮质量浓度情况分别为：铵态氮10ｍｇ／L左右、硝态氮40～60ｍｇ／L、有机氮40ｍｇ／L或80ｍｇ／L左右。对于两种无机氮源，四尾栅藻对铵态氮的利用效率较硝态氮的高；对于有机氮源，在合适的浓度范围内，四尾栅藻可以较好地利用尿素作为氮源，其最大生物量远远大于另外两种无机氮源，相应的最大比增长速率亦大于两种无机氮源。     

富营养化湖塘底泥氮磷吸附—解吸模拟研究

当外源营养盐负荷得到控制后,水体底泥中氮、磷等营养物质的释放成为诱发水体富营养化的重要内因。通过室内实验模拟富营养化湖塘底泥中氮、磷的吸附与解吸过程,对比分析不同氮、磷浓度条件下,上覆水—底泥间氮、磷吸附与解吸过程中的特点,探讨了影响氮、磷吸附和解吸关键因素,揭示了底泥氮、磷吸附和解吸平衡质量浓度,为制定科学的底泥内源氮、磷的控制措施提供科学依据。     

基于斜生栅藻培养的城市生活废水资源化利用研究

为降低微藻培养成本,实现城市生活废水的资源化利用,研究了补加不同质量浓度的Na NO3、K2HPO4·3H2O、Mg SO4·7H2O、Fe Cl3·6H2O、Na2CO3营养盐情形下,斜生栅藻(Scenedesmus obliquas)的生长和油脂积累特性。结果表明:城市生活废水中自身含有的磷、碳基本满足微藻正常的生长和油脂代谢,同时在低氮和高铁环境下更有利于微藻油脂的积累。此外,在补加Na NO3质量浓度2.25 g/L、K2HPO4·3H2O质量浓度40 mg/L、Mg SO4·7H2O质量浓度56.25 mg/L、Fe Cl3·6H2O质量浓度9 mg/L、Na2CO3质量浓度15 mg/L的条件下,斜生栅藻生长状况良好,生物量可达3.04 g/L,是废水原液条件下的2.8倍。利用城市生活废水来培养富油的微藻,可以实现废水的资源化利用与微藻的低成本培养,对工业化生产具有重要意义。     

再生水回用于景观水体磷营养盐对叶绿素a和藻密度的影响研究

以北京市某再生水厂出水为研究对象,人工配制各浓度梯度的营养盐,试验研究补给再生水后景观水体水质指标的变化,重点考察磷对叶绿素a和藻密度的影响情况.试验结果表明叶绿素a和藻密度主要受水体中氮磷比和磷酸盐浓度的影响.在磷酸盐保持在1 mg/L以下,氨氮在2 mg/L以下,硝酸盐氮在8 mg/L以下,将再生水一次性补给景观水体是完全可行的,不会产生藻类暴发;当磷酸盐浓度增加至1.5 mg/L,藻密度将显著增加.     

再生水回用于景观水体氮营养盐对叶绿素a和藻密度的影响研究

再生水回用于景观水体是否会带来严重的生态风险,尚需广泛而深入的研究。以北京市某再生水厂出水为研究对象,人工配制各浓度梯度的营养盐,试验研究补给再生水后景观水体水质指标的变化,重点考察氮营养盐(氨氮、硝酸盐氮)对叶绿素a和藻密度的影响情况。试验结果表明叶绿素a和藻密度主要受水体中氮磷比和磷酸盐浓度的影响,与单独的硝酸盐氮浓度增加并无直接的关系。当磷酸盐浓度保持在1mg/L以下,氨氮浓度在4mg/L以下,硝酸盐氮浓度在16mg/L以下,将再生水一次性补给景观水体是可行的,不会产生藻类暴发。     

淡水藻类生长的环境影响因子分析——以铜绿微囊藻为例

淡水藻类的快速生长易导致水体"水华"。藻类生长受其自身生理特征和外界环境因子共同作用。选取"水华"爆发常见的藻种——铜绿微囊藻为研究对象,通过总结国内外相关实验以及理论研究成果,分析环境因子包括氮、磷营养盐(浓度、形态及氮磷比)、光照(强度和周期)、温度、pH、盐度及水力扰动对其生长的影响。基于上述讨论分析总结藻类生长的适宜环境条件,提出抑制藻类"水华"的必要控制措施和相关技术构想。     

Nutrient footprints on the Toronto-Mississauga waterfront of Lake Ontario

The extent of nutrient enrichment over the urbanized shoreline of western Lake Ontario bordering the Cities of Toronto and Mississauga was investigated in 2018. Concentrations of total phosphorus were higher and more wide-ranging compared with nearshore reference areas in eastern Lake Ontario. Area-weighted chlorophyll a was higher over the shoreline from the mouth of the Credit River to Humber Bay west of Toronto Harbour compared with that to the east from the Toronto Beaches to the Rouge River, a pattern also seen broadly in concentrations of phosphorus fractions and nitrates. Concentrations of phosphate measured by mass spectrometry, and using an internal standard to minimize sampling losses, were higher in Toronto Inner Harbour, near wastewater outfalls, river mouths, and to varying extent over the mixing areas of these discharges. Chlorophyll a suggested broadly oligotrophic to oligo-mesotrophic conditions despite areas with nutrient fractions suggestive of more productive conditions. Toronto Inner Harbour was mesotrophic, with wide-ranging levels of phosphorus fractions strongly influenced by the variable loading from the Don River into the harbour. Phosphorus fractions in the harbour quays which also receive CSOs discharges were elevated at times. Blooms or scums of planktonic algae were not observed. Elevated concentrations of phosphate were found at shallow depths suitable for growth of the green algae Cladophora. As these urban areas continue to grow, the potential for additional nutrient loading to exacerbate growth of algae should be watched given the present conditions that indicate variable but pervasive nutrient enrichment.     

Phytoplankton community and algal growth potential in Taipinghu Reservoir, Anhui Province, China

An integrated investigation of the community structure and growth potential of algae in Taipinghu Reservoir, Anhui Province, China, was conducted from July 1993 to October 1994. A total of 112 algal species belonging to eight phyla were observed. Green algae were the dominant population, representing 55% of the total recorded taxa. Diatoms and blue‐green algae formed the second and the third largest algal groups, respectively. The total species and population of algae were relatively steady in spring, summer and autumn, but exhibited some variety in winter. Compared to earlier data, the species richness decreased by 36% and the number of genera decreased by 23% over an eight‐year period. The maximum values of the annual mean cell count, biomass and chlorophyll a concentration appeared in summer and the minimum in winter. The algal growth potential of the original water without supplemental nutrients was much lower than that of the control culture, but equal to or a little higher than the control culture which was supplemented with complete nutrients. The study results imply that phosphorus is the limiting nutrient for algal growth and that the trophic status of the reservoir is changing from mesotrophic to eutrophic. Based on these data, some advice on how to manage the reservoir is offered.     

Phosphorus,Nitrogen, and Silica as Controls on Phytoplankton Biomass and Species Composition in Lake Champlain (USA-Canada)

The long-standing assumption that the phytoplankton in Lake Champlain are phosphorus limited was tested through measurement of physiological indicators of phosphorus status (alkaline phosphatase activity and orthophosphate turnover time) and enrichment experiments conducted four times during the growth season. Phosphorus addition to experimental carboys incubated 4–5 days in situ substantially increased phytoplankton biomass relative to controls in June, but had only a mild impact in July and September, and no effect in May. Nitrogen addition augmented biomass in one of four experiments (in June), while silica had no impact at any time. In summer and fall, addition of N and P in combination always yielded more phytoplankton biomass than singular P addition. In spring, even combined addition of N, P, and Si failed to stimulate phytoplankton growth. The phytoplankton groups responding to fertilization were largely the same as those that flourished in controls (diatoms and green algae), suggesting that enclosure was a more powerful determinant of species composition than nutrient inputs. Orthophosphate turnover times and levels of alkaline phosphatase activity in the lake indicated spatial and temporal variability in phytoplantkon P status, with P sufficiency as common as P deficiency. We conclude that multiple interacting factors influence the abundance and species composition of phytoplankton in Lake Champlain. In spring, phytoplankton growth is not limited by N, Si, or P, but by some factor yet to be determined (perhaps light or temperature). In summer, P is the principal limiting nutrient, but N exerts an influence that deserves further investigation.     

Lake Jabel restoration project: Phosphorus status and possibilities and limitations of diversion of its nutrient-rich main inflow

External and internal phosphorus loading was studied in 1996 in the anthropogenically eutrophicated Lake Jabel, which is located in Mecklenburg (north‐eastern Germany). It has a dimictic 23‐m‐deep northern basin, a 19‐m‐deep middle basin and a 6‐m‐deep polymictic southern basin. The main tributary, Grabowhöfer Grenzgraben, which enters via a leaching field from a waste‐water treatment plant, has been identified as the major nutrient discharge (80% of total phosphorus loading) into the northern basin. The sediment is the second largest source of phosphorus for Lake Jabel, contributing 25.7%, 27.4% and 2.4% of the overall phosphorus load to the northern, middle and southern basins, respectively. Although the favoured diversion of the Grabowhöfer Grenzgraben would contribute to a reduction of 1.22 t P and 20.94 t NO₃^‐–‐N per year, it is mainly rejected for the following reasons. If the extreme monthly nitrate supply, between 4.84 and 189.6 mg N m^‐2 day^–1 ceased, the release of redox‐sensitive phosphorus in the northern basin would increase by a factor of 0.54, which is with 41.1% total phosphorus, twice as high as that in the middle basin. In addition, the nitrate supply can substantially lower the seasonal precipitation of stable iron sulphides, which would otherwise lower the concentration of redox‐sensitive phosphorus, but cannot change the phosphorus retention in the long term. Because of internal phosphorus sources, the diversion of the Grabowhöfer Grenzgraben would result in no substantial changes in the level of trophy.     

长江中、下游干流磷的沿程分布特征研究

为了解长江中下游磷营养盐的分布特征及磷素的污染状况,2014年5月29日至6月7日沿长江中、下游干流在湖北武汉,江西九江,安徽安庆,江苏的南通、镇江、南京,上海等地设置采样断面,现场监测表层、中层和底层水体中总磷（TP）、溶解性总磷（TDP）、颗粒态总磷（TPP）、溶解性正磷酸盐（SOP）的含量,分析干流磷的沿程分布特征。研究结果表明：长江中、下游干流各采样地TP平均含量范围在0．15～0．25 mg／L,各采样地下游TP平均含量高于上游,各采样地下游左岸及右岸TP平均含量较中泓处高,且左岸TP平均含量较右岸高;各采样地TDP平均含量范围为0．02～0．13 mg／L,且采样地下游TDP平均含量较上游高;各采样地TPP平均含量范围为0．10～0．20 mg／L,沿长江中下游沿程方向TPP占TP百分比逐渐减小,但TPP仍是长江中下游TP的主要贡献者,TPP分布与叶绿素a的分布极为相似,二者呈显著正相关;各采样地SOP平均含量范围为0．02～0．11 mg／L,且 SOP平均含量沿长江中、下游沿程方向显示出增加趋势,SOP是TDP的主要组成部分,SOP平均含量占TDP平均含量70％以上。总体上,长江中下游水体中各形态磷含量较低,水质良好。     

水库水动力对水体富营养化影响

当氮磷浓度达到富营养水平时,水动力条件(流量、流速和水位)可能成为制约因子,抑制水华发生.河道型深层出水的水库相对于湖泊型表层出水的水库,因为较大交换流量,较低营养盐浓度,保证了浮游植物和藻类较低的现存量.进一步研究水文条件(滞留时间、水位变化和水流运动)发现,保持较低的滞留时间、较高的水位和底层较低的流速,都有利于水库水体中营养盐和藻类的稀释,不利于浮游植物和藻类的生长,减缓水体富营养化进程.     

基于植被混凝土的不同优势物种根际土壤养分及微生物量化学计量特征差异

为探索不同优势物种对植被混凝土基材肥力的影响,采集向家坝植被混凝土3种优势物种(葛藤(PL)、荩草(AH)、双花草(PA))根际(R)和非根际(N-R)土壤,对土壤的养分和微生物生态化学计量比进行研究。结果表明:①各植物根际土壤养分和微生物量高于非根际,根际表现出明显的富集作用。葛藤对除速效磷外的其他养分的富集作用均较荩草和双花草明显,大部分养分富集作用在荩草和双花草之间差异不显著。葛藤非根际土壤养分和微生物活性低于荩草和双花草。②各植物的碳、氮、磷比都表现为根际土壤大于非根际土壤,葛藤根际土壤C/N和C/P大于荩草和双花草。3种植物根际土壤MBC/MBN差异不大。荩草和双花草非根际MBC/MBN和MBC/MBP均显著大于葛藤(P<0.05)。葛藤根际土壤MBC/MBP和MBN/MBP显著大于荩草和双花草(P<0.05)。相对中国和世界土壤平均水平,3种植物根际和非根际土壤具有较高的C/N和MBC/MBN,C/P、N/P、MBC/MBP和MBN/MBP均较低。③相关性分析表明,MBN、有机碳、总氮、总磷和速效氮之间具有极显著的正相关关系(P<0.01),但MBP只与速效磷有显著的正相关关系(P<0.01)。综合分析表明植物对植被混凝土基材养分固存起到了积极的作用,葛藤根际富集能力较强。此外,基材磷素含量过高,而氮素含量缺乏,基材养分配比不均衡。     

Non-Point Source Pollution from Abandoned Agricultural Land in the Great Lakes Basin

The contribution of abandoned farm fields to non-point source pollution in the Great Lakes Basin was studied on a 7.73 ha old field watershed near East Lansing, Michigan, that had been abandoned 18 years prior to the study. Exports of nitrogen were low and approached values expected for undisturbed forests in the Great Lakes Basin. Exports of phosphorus were slightly elevated compared to undisturbed forests. Exports and concentrations of both N and P were similar to values listed for cleared, unproductive land for the Great Lakes region by the recent nationwide survey of EPA. Annual exports of total P, PO₄–P, NO₃–N, NO₂–N, NH₄–N, Organic–N, Cl, Na, Ca, and suspended solids are given. Most exports of all constituents occurred during rainfall or snow-melt generated runoff events during the spring runoff period. Soil and soil-water nutrient concentrations were low, reflecting the low fertility of the study watershed. Nutrient concentrations in runoff reflect this low fertility and would be higher from recently abandoned farm land. The contribution of abandoned fields to nutrient loading of the Great Lakes would decrease from levels typical of agricultural runoff at time of abandonment to levels typical of undisturbed forests within 15 to 20 years following abandonment.