流溪河水库丰水年与枯水年营养盐动态的比较分析

流溪河水库是一座位于北回归线上的大型山谷型水库,典型的热带-亚热带过渡区水体。为了解该水库的营养盐动态特征,于2008-2009年对水库的营养盐状况和环境因子进行了逐月监测,分析了其丰水年(2008)和枯水年(2009)营养盐动态的动态特征和影响因素。两年的降雨量分别为2660mm和1583mm,降雨主要集中在季风期(4-9月)。丰水期初期(4-5月)是全年营养盐浓度最高的时期,该时期丰水年与枯水年的营养盐空间分布相似:营养盐浓度沿入库河流至水库大坝方向递减,地表径流带来的外源输入是这个期间营养盐变化的主要因素。河流区的营养盐主要受地表径流带来的外源输入的影响,湖泊区营养盐主要受水位变化导致的内源输入的影响。较大的降雨量差异导致两年不同的营养盐季节动态,丰水年有着更高的营养盐水平,更小的DIN/TN与DIP/TP值。河流区较高的营养盐水平会带来湖泊区较高的TN浓度,但不会导致湖泊区更高的TP浓度。     

茅尾海营养状况及其来源研究

根据2008年茅尾海海域水质调查结果,采用营养指数法、营养状态质量指数法、有机污染指数法对海湾营养状况进行了评价,并结合2007年入海污染源调查结果,探讨了茅尾海的营养盐来源。结果表明:茅尾海受无机氮污染较重,海域处于呈富营养状态,有机污染程度属2级,表明开始受到有机污染。营养盐高值区集中在北部海域和东部海域。钦江、茅岭江等入海河流携带入海的营养盐是海域营养的主要来源,占入海污染物总量的79%以上,其次来自钦州湾外海的混合排污口。2001~2007年茅尾海DIN、DIP年均浓度分别与入海河流氮、磷营养盐入海负荷呈显著正相关,两者的相关系数分别为0.873和0.824。     

大沙河水库主要入库河流氮磷营养输入分析

为了解大沙河水库流域内营养盐输入对水库水质的影响,以 2011年3月~2012年2月大沙河水库5条主要入库河流(大沙河、白沙河、双石河、富食河和沃江河)的水文水质监测数据为依据,分析了这些入库河流的流量和氮磷营养盐浓度,并估算了外源负荷总量,旨在为水库进行高效和合理的流域规划以及水质保护方案的制定提供科学依据。结果表明:位于西南方向的白沙河年平均流量最大(1.01 m³·s^-1),西北部富食河流量最小(0.23 m³·s^-1)。各入库河流总氮平均浓度变化范围为1.62~4.37 mg·L^-1,总磷平均浓度范围为0.08~0.36 mg·L^-1,其中富食河氮和磷营养盐的浓度最高,大沙河总氮浓度最低,白沙河总磷浓度最低,总体上西北部河流的氮磷浓度高于西南部河流。全年大沙河水库总氮输入量为176.7 t,总磷输入量为13.7 t。在所有入库河流中,位于水库北部的沃江河对水库营养盐输入量贡献最大,氮、磷负荷分别占总输入量的33%和32%,位于西部的双石河氮负荷最小(12%),西南方向大沙河磷负荷最小(9%)。     

高州水库氮磷营养盐变化特征及水质管理对策

通过2012-2013 年对广东省高州水库氮磷营养盐的趋势变化进行分析, 探讨了水库中氮磷浓度的变化特征,并从水库管理与水动力学两方面对水库水质管理对策进行了讨论。研究结果表明: 高州水库总氮、总磷浓度均表现为丰水期高, 说明受强降雨的影响, 农业面源污染携带大量的氮磷随地表径流进入库区, 致使库区氮磷营养盐含量升高。其次, 入库河流是库区氮磷营养盐的主要来源。氮磷比分析结果表明, 高州水库流域内部分水体在时空上处于氮限制与磷限制交替出现的状态, 且氮磷比与总磷呈现显著地正相关, 进一步反应了高州水库水体主要处于磷素限制状态。水库上游集雨区人口分布集中, 大量的生活排污与农业面源污染的输入是库区营养盐的主要来源; 合理处理上游居民生活垃圾并严格控制工业污染, 是降低库区营养盐的主要途径。此外, 人为改变高州水库的出流方式, 可以抑制浮游植物及藻类的生长, 从而减少水库富营养化的可能。     

湖泊生态系统弹性系数理论及其应用

在湖泊生态系统健康评价的基础上,分析城市湖泊营养状态的特殊性,论证得出响应型和非响应型湖泊的生态系统健康指数(EHI)与营养状态指数(TSI)近似呈二次函数关系.提出湖泊生态系统弹性系数,对生态系统健康指数(EHI)做出适当改进.改进后的生态系统健康指数(EHI′)能够更好地反映各类型湖泊的健康状态,完善了Xu等的EHI理论并扩展了其应用范围,是目前最为接近Costanza对HI定义的可量化计算的数学公式和方法,并成功用于厦门杏林湾生态系统健康评价.     

淡水湖泊附着藻类生态学研究进展

附着藻类是淡水生态系统初级生产者的主要组成部分,对淡水生态系统营养盐循环及沉水植物分布具有重要的影响。本文对近年来淡水湖泊生态系统中附着藻类群落组成、生态功能以及主要影响因子进行了分析,从附着藻类种群结构入手,指出附着藻类通过改变群落中优势种的组成来适应不同的环境,阐述了附着藻类在湖泊生态系统营养盐循环中的作用及其与沉水植物之间的关系。针对淡水湖泊富营养化问题,提出了今后附着藻类生态学研究应侧重于:主要因子(如弱光、高浓度的营养盐等)的交互作用对附着藻类的影响,原位实验方法弄清楚附着藻类在湖泊生态系统碳、氮、磷生物地球化学循环中的作用,以及富营养湖泊附植藻类与沉水植物相互作用的机理。     

广东大中型供水水库的磷污染与富营养化分析

2000年丰水期和枯水期对广东大中型水库的磷污染和富营养化现状进行了调查。结果表明,在调查的20个大中型供水水库中,一半以上的水库受到磷污染,磷污染已成为水库富营养化的重要原因。水库的总磷浓度与水库的营养状态基本一致。水库普遍存在磷限制现象,且枯水期的磷限制现象更为严重。在低温和磷限制条件下,硅藻比绿藻更加有优势。     

基于大型底栖无脊椎动物确定河流营养盐浓度阈值——以西苕溪上游流域为例

水体富营养化是一个全球性的问题,中国也面临严重威胁.目前,中国的水体富营养化研究主要集中在湖泊和水库,对河流的研究极少.根据大型底栖无脊椎动物的群落结构对营养盐胁迫的响应,运用非参数转变点分析方法计算西苕溪上游营养盐浓度突变点.结果表明:总氮和总磷的突变点分别为1.409mg·mL-1和0.033～0.035mg·mL-1.参照点的总氮和总磷浓度基本都低于阈值,城市干扰点则全部高于阈值,而当总氮和总磷超过各自阈值时会导致大型底栖无脊椎动物群落结构的严重退化.通过建立与水生生物群落结构有关的水体营养盐标准,可充分发挥生物监测在水环境管理中的作用,为计算水体中总氮和总磷的最大日负荷总量提供科学数据.     

北京市北环水系富营养化因子分析

以北京市北环水系水体为例,利用聚类分析将研究区分为河流子系统和湖泊子系统.因子分析表明,河流子系统第一主成分富营养元素为总磷(TP)、总氮(TN)和氨氮(NH₄-N),第二主成分为温度(T)和溶解氧(DO);湖泊子系统第一主成分为总氮和氨氮,第二主成分为总磷、酸碱度(pH)、透明度(SD)和温度,第三主成分为溶解氧和叶绿素a(Chla),表明研究区的水体富营养化主要由富营养盐负荷引起.结合逐步回归分析方法,建立富营养水平预测回归模型,根据模型自变量选择证明河流子系统富营养化特征为磷限制型,湖泊子系统为氮限制型.从水量和水质上对营养盐浓度负荷变化分析表明,研究区年最小生态环境用水为4872×10⁴m³,1990～1998年,除1998年外,现实的生态环境需水均不能满足需求.随着流域人口的不断增长,生活污水、城市径流和固体废弃物淋溶液中营养物质进入水体,研究区营养盐浓度负荷有随时间不断增长的趋势,针对这种趋势提出了应对措施.     

不同营养条件对金鱼藻净化作用及其生理生态的影响

以沉水植物金鱼藻（Ceratophyllum demersum）为研究对象,研究了较高营养条件（N:1030 mg/L,P:13 mg/L）对金鱼藻去除氮、磷能力的影响,金鱼藻的含磷量、生物量与净光合作用速率对营养负荷的响应。结果表明,金鱼藻-沉积物处理系统可有效去除氮、磷（去除率80%以上）,但去除效率随水中营养盐浓度的升高而下降。试验结束时各试验组金鱼藻总磷含量达7.0113.09 mg/g （平均9.03 mg/g）,显著高于对照组（2.853.17 mg/g,平均3.05 mg/g）,表明金鱼藻可以吸收水体中的磷。营养盐对金鱼藻生长有明显抑制,其抑制作用随营养盐浓度增高而加剧,除对照组外,各试验组金鱼藻均有叶片脱落,试验结束时金鱼藻生物量降至初始生物量的48.3%63.3%。在较高营养水体中,金鱼藻的净光合作用速率由试验开始时-0.0370.058 mg/（gh）显著上升至试验结束时0.180.44 mg/（gh）,而对照组变化不大,这表明在试验后期,随着水体营养盐浓度降低,金鱼藻开始进行恢复性生长,说明水体营养盐浓度对金鱼藻的净光合作用速率和生长速率有明显影响。金鱼藻尚不适宜作为滇池草海生态修复的先锋物种。       

Factors related to variance of residuals in chlorophyll — total phosphorus regressions in lakes and reservoirs of Argentina

Data from an extensive mid-summer survey of Argentinian lakes and reservoirs were used to study the effects of variability in internal processes on the residual variance in chlorophyll — total phosphorus (CHL-TP) regression models. These effects were compared with those related to the external characteristics of lakes, e.g. climate, morphometry and nutrient status. Zooplanktivorous fish biomass, mean macrozooplankton size, dissolved oxygen at the sediment-water interface, and submersed macrophyte development, were shown to be significant in explaining residual variance in CHL-TP for Argentinian lakes and reservoirs. The results suggest that those variables have discontinuous or threshold effects on CHL-TP residuals among lakes. Significant differences were also shown between CHL-TP regressions for lakes with and without zooplanktivorous fish and for lakes with small or large macrozooplankton. Lakes with zooplanktivorous fish, small body size macrozooplankton, and very low hypolimnetic oxygen also have higher chlorophyll levels than predicted from CHL-TP regression models.     

Ambiguous climate impacts on competition between submerged macrophytes and phytoplankton in shallow lakes

1. Shallow lakes may switch from a state dominated by submerged macrophytes to a phytoplankton‐dominated state when a critical nutrient concentration is exceeded. We explore how climate change may affect this critical nutrient concentration by linking a graphical model to data from 83 lakes along a large climate gradient in South America. 2. The data indicate that in warmer climates, submerged macrophytes may tolerate more underwater shade than in cooler lakes. By contrast, the relationship between phytoplankton biomass [approximated by chlorophyll‐a (chl‐a) or biovolume] and nutrient concentrations did not change consistently along the climate gradient. In warmer climates, the correlation between phytoplankton biomass and nutrient concentrations was overall weak, especially at low total phosphorus (TP) concentrations where the chl‐a/ TP ratio could be either low or high. 3. Although the enhanced shade tolerance of submerged plants in warmer lakes might promote the stability of their dominance, the potentially high phytoplankton biomass at low nutrient concentrations suggests an overall low predictability of climate effects. 4. We found that near‐bottom oxygen concentrations are lower in warm lakes than in cooler lakes, implying that anoxic P release from eutrophic sediment in warm lakes likely causes higher TP concentrations in the water column. Subsequently, this may lead to a higher phytoplankton biomass in warmer lakes than in cooler lakes with similar external nutrient loadings. 5. Our results indicate that climate effects on the competitive balance between submerged macrophytes and phytoplankton are not straightforward.     

Detrital aggregates in some Iowa lakes and reservoirs

Detrital aggregates in three eutrophic Iowa lakes and four eutrophic Iowa reservoirs were studied with light and scanning electron microscopy to determine if aggregate morphologies and concentrations were similar. Lake and reservoir aggregates were composed of organic and inorganic particles bound together in an organix matrix. Many of the inorganic particles were calcium carbonate. Obvious bacterial and fungal attachment to the aggregates was rare. Aggregate concentrations ranged from 4 to 274 million aggregates per liter. Aggregates smaller than 18 μm diameter dominated the hyperbolic size-frequency distribution of aggregates in all lakes. Reservoir and lake aggregate concentrations did not differ significantly, but mean aggregate concentrations were directly correlated to the mean chlorophyll a concentration of the lakes. These data strongly suggest that detrital aggregate concentrations are influenced by the trophic status of a lake. Journal Paper No. J-8705 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project 2051. Journal Paper No. J-8705 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project 2051.     

Light and nutrient control phytoplankton biomass responses to global change in northern lakes

Global change affects terrestrial loadings of colored dissolved organic carbon (DOC) and nutrients to northern lakes. Still, little is known about how phytoplankton respond to changes in light and nutrient availability across gradients in lake DOC. In this study, we used results from whole‐lake studies in northern Sweden to show that annual mean phytoplankton biomass expressed unimodal curved relationships across lake DOC gradients, peaking at threshold DOC levels of around 11 mg/L. Whole‐lake single nutrient enrichment in selected lakes caused elevated biomass, with most pronounced effect at the threshold DOC level. These patterns give support to the suggested dual control by DOC on phytoplankton via nutrient (positively) and light (negatively) availability and imply that the lakes' location along the DOC axis is critical in determining to what extent phytoplankton respond to changes in DOC and/or nutrient loadings. By using data from the large Swedish Lake Monitoring Survey, we further estimated that 80% of northern Swedish lakes are below the DOC threshold, potentially experiencing increased phytoplankton biomass with browning alone, and/or combined with nutrient enrichment. The results support the previous model results on effects of browning and eutrophication on lake phytoplankton, and provide important understanding of how northern lakes may respond to future global changes.     

Deriving nutrient targets to prevent excessive cyanobacterial densities in U.S. lakes and reservoirs

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Limnology of tropical impoundments: a comparative study of the major reservoirs in Madras State (India)

Summary A limnological study of seventeen man-made lakes has been made. Thermal features showed absence of stable thermal stratification. Cognisable thermocline did not exist. The South-Western reservoirs with low nutrient and salt content were very poor in productivity, but the high alkaline reservoirs were also not very productive. Some reservoirs with lower alkalinity, hardness and total solids developed algal blooms and were highly productive. Bhavanisagar and Stanley reservoirs with optimal levels of dissolved salts and alkalinity-hardness were fairly productive. Reservoirs with organic soils were better in productivity than those with higher silica content (Hope Lake, Poondi Reservoir, Vaigai etc.) Dissolved oxygen depletion in the bottom was characteristic of productive waters. Total oxygen depletion occurred in some of them but in a few depletion was rare and not of great severity. Klinograde curves were characteristic of productive reservoirs. Even when the bottom waters were low in or were devoid of dissolved oxygen the outflow from this level picked up oxygen within a short distance of 100 m. Effect of water replacement on plankton production is discussed. Primary production in the reservoirs has been compared and discussed. It is the silt-laden turbid waters that are poor in production. Water releases could be manipulated to assist spawning of fishes and for amelioration of pollution downstream.     

Increased nutrient loading and rapid changes in phytoplankton expected with climate change in stratified South European lakes: sensitivity of lakes with different trophic state and catchment properties

We hypothesised that increasing winter affluence and summer temperatures, anticipated in southern Europe with climate change, will deteriorate the ecological status of lakes, especially in those with shorter retention time. We tested these hypotheses analysing weekly phytoplankton and chemistry data collected over 2 years of contrasting weather from two adjacent stratified lakes in North Italy, differing from each other by trophic state and water retention time. Dissolved oxygen concentrations were higher in colder hypolimnia of both lakes in the second year following the cold winter, despite the second summer was warmer and the lakes more strongly stratified. Higher loading during the rainy winter and spring increased nutrient (N, P, Si) concentrations, and a phytoplankton based trophic state index, whilst the N/P ratio decreased in both lakes. The weakened Si limitation in the second year enabled an increase of diatom biovolumes in spring in both lakes. Chlorophyll a concentration increased in the oligo-mesotrophic lake, but dropped markedly in the eutrophic lake where the series of commonly occurring cyanobacteria blooms was interrupted. The projected increase of winter precipitation in southern Europe is likely to increase the nutrient loadings to lakes and contribute to their eutrophication. The impact is proportional to the runoff/in-lake concentration ratio of nutrients rather than to the retention time, and is more pronounced in lakes with lower trophy.     

提高水体净化能力控制湖泊富营养化

建立了湖泊污染物质动力学方程,根据我国湖泊和美国O keechobee湖资料,确定了控制藻类暴发的总磷阈值为0.035m g/L,总氮阈值为0.350m g/L(滇池)和1.050m g/L(太湖);用实测资料,计算得到需要削减的外污染源滇池为总磷、总氮各78%,太湖为总磷69%、总氮56%。提出通过提高水体净化能力可以控制湖泊富营养化的理论依据和如下技术路线:提高湖泊净化率,使其超过输入的污染率,在湖内实现浓度低于控制藻类水华暴发所需要的磷、氮阈值;因地制宜综合运用到太湖、巢湖、滇池等一类大、中型湖泊,加强管理,就可以在占湖泊7%(滇池)和4%(太湖)的湖面上,依托科学布设控制其生长的凤眼莲,将其规模化地加工为有益产品,从而有效地去除湖泊中的营养盐,将水体综合净化率比现有净化率在滇池提高4.6倍,在太湖提高2.1倍,实现控制湖泊富营养化目标,并同步地在约3~4倍相应面积上修复健康水生态系统。     

Five Serbian reservoirs contain different fungal propagules

This paper presents results of a mycological survey conducted in five large reservoirs in Serbia (Sjenica, Barje, Garasi, Meduvrsje and Ovcar-Kablar) that have different hydrobiological and production characteristics. The sampling was conducted in March, June, August and October 2002. Quantitative analysis of fungal communities showed that the average number of colony-forming units in these reservoirs was 1966-5682/L of water. The highest number of CFUs was found in the alpha-mesosaprobic (Class III) Ovcar-Kablar Reservoir and the lowest was in the oligosaprobic (Class I) Sjenica Reservoir. CFUs were higher in samples taken near lake bottoms and in littoral zones rich with macrovegetation than in the middle depths. In these reservoirs 48 species were identified from 720 isolates. The dominant genera were Penicillium, Aspergillus, Cladosporium, Fusarium, Rhizopus, Mucor, Phoma and Verticillium. The autochthonous aquatic fungal community comprised these species: Achlya americana, A. diffusa, A. racemosa, Dictyuchus sterile, Isoachlya toruloides, Leptomitus lacteus, Pythium ultimum, Saprolegnia ferax, S. hypogyna and S. monica. My results indicate that aquatic fungi on the whole are better represented in lakes with a higher trophic status.     

Nitrogen and Phosphorus Limitation of Phytoplankton Growth in New Zealand Lakes: Implications for Eutrophication Control

We examine macronutrient limitation in New Zealand (NZ) lakes where, contrary to the phosphorus (P) only control paradigm, nitrogen (N) control is widely adopted to alleviate eutrophication. A review of published results of nutrient enrichment experiments showed that N more frequently limited lake productivity than P; however, stoichiometric analysis of a sample of 121 NZ lakes indicates that the majority (52.9%) of lakes have a mean ratio of total nitrogen (TN) to total phosphorus (TP) (by mass) indicative of potential P-limitation (>15:1), whereas only 14.0% of lakes have mean TN:TP indicative of potential N-limitation (<7:1). Comparison of TN, TP, and chlorophyll a data between 121 NZ lakes and 689 lakes in 15 European Union (EU) countries suggests that at the national scale, N has a greater role in determining lake productivity in NZ than in the EU. TN:TP is significantly lower in NZ lakes across all trophic states, a difference that is driven primarily by significantly lower in-lake TN concentrations at low trophic states and significantly higher TP concentrations at higher trophic states. The form of the TN:TP relationship differs between NZ and the EU countries, suggesting that lake nutrient sources and/or loss mechanisms differ between the two regions. Dual control of N and P should be the status quo for lacustrine eutrophication control in New Zealand and more effort is needed to reduce P inputs.