长江中下游湖泊沉积物酶活性及其与富营养化的关系

为揭示富营养化湖泊沉积物营养物分解合成过程的生物化学机制,研究了长江中下游6个浅水湖泊沉积物氮、磷、有机质和铵氮含量,水解酶、氧化还原酶活性,微生物种类与数量及之间的关系.结果表明:大通湖、珊珀湖、赛城湖和军山湖等养殖型湖泊,污染严重,其沉积物脲酶活性明显高于污染程度轻的大型湖泊鄱阳湖和洞庭湖,且与沉积物总氮(TN)、有机质(OM)含量呈极显著正相关(r=885,P<0.01;r=0.900,P<0.01);沉积物碱性磷酸酶(APA)活性与总磷(TP)含量呈极显著正相关(r=0.986,P<0.01).湖泊沉积物过氧化氢酶、多酚氧化酶与过氧化物酶活性变化趋势相近,分布状况与湖泊污染程度、人类活动干扰程度等紧密相连.湖泊沉积物微生物以细菌为主,放线菌次之,真菌最少.各湖泊氨化细菌数量差异较小,而反硝化细菌数量差异较大,反硝化细菌可能是导致该区域湖泊沉积物氮素累积的重要生物指示因子,可以作为反映湖泊富营养化程度的生物指示因子.     

中国湖泊富营养化影响因素研究——基于中国22个湖泊实证分析

基于1：25万河流水系和数字高程（DEM）数据制备了选取湖泊的流域边界,据其集成了流域社会经济数据,并据中国科学院资源环境数据中心提供的1990、1995、2000、2005年4个时段土地利用数据形成了流域反映人类活动强度的表征指标,选取了全国湖泊富营养化区域差异性调查课题获取的案例湖泊的水质数据,集成了中国湖泊富营养化影响因素计量分析的面板数据集,研究了1990-2005年间中国湖泊营养状态的发展趋势与差异特征,探讨了湖泊富营养化的自然气候与社会经济影响机制,构建了中国湖泊富营养化影响因素分析的计量模型,厘定了1990-2005年间影响湖泊营养状态变化的重要因素,测度了其对湖泊富营养化的影响方向和作用强度。基于面板数据的计量分析结果表明,近15年人类活动强度对湖泊营养状态呈显著的正影响,其表征指标人均GDP与建设用地所占流域面积比均具有较强的显著性,而在人类扰动较小的情况下,湖泊的营养状态与湖泊补给系数成正比,与湖泊蓄容量成反比,补给系数较小且其他因素也相同时,水体营养状态应与流域土壤本底值相关;以林、草地的面积比重所测度的流域自然生态系统发育程度与湖泊营养状态呈显著负相关关系,表明林地与草地生态系统对流域的氮、磷营养物的人湖量具有一定的削减作用,论文研究结果将为流域管理措施方案制订提供科技支撑。     

浅水富营养化湖泊巢湖近百年重金属污染的沉积物记录

浅水富营养化湖泊巢湖近百年重金属污染的沉积物记录湖泊沉积物中重金属的富集主要与流域的人类活动密切相关,其剖面分布反映了流域人类活动与自然环境相互作用的过程,是评价湖泊环境现状及演变趋势、识别流域主要环境问题的一个重要标志.中国湖泊历史监测数据稀缺,利用高分辨率沉     

中国东部浅水湖泊沉积物总氮总磷基准阈值研究

受人类活动的影响,东部浅水湖泊沉积物中总氮、总磷负荷很高,当外来污染源得到控制时,底泥中的营养盐会逐渐释放出来,对湖泊水质与生态系统影响很大。为合理削减湖泊内源污染,控制沉积物中营养盐向上覆水体释放,研究制定东部浅水湖泊沉积物总氮、总磷基准阈值,分别测定了100个湖泊的896个表层沉积物样品和8个典型湖泊11个柱芯的沉积物总氮（TN）、总磷（TP）含量,分析了沉积物TN、TP浓度剖面分布特征。通过频度分布法对100个湖泊沉积物总氮总磷的污染状况进行评价,通过背景值比较法确定了8个典型湖泊沉积物的TN、TP背景值。结果表明,100个湖泊的表层沉积物TN浓度范围在479.70~5 573.65 mg·kg-1,TP浓度范围在248.44~1000.33 mg·kg-1,不同湖泊表层沉积物中TN、TP值差异较大。8个典型湖泊沉积物总氮、总磷含量整体上表现出随着深度增加而下降变化趋势,在深层沉积物中含量保持稳定。所调查8个湖泊TN均值为1443.83 mg·kg-1,变化范围为247.45~3719.46 mg·kg-1,各湖泊中TN均值表现为：沱湖〉焦岗湖〉花园湖〉七里湖〉北民湖〉大通湖〉城东湖〉瓦埠湖;TP均值为519.62 mg·kg-1,变化范围为225.41~1944.89 mg·kg-1,各湖泊中TP均值表现为：北民湖〉大通湖〉七里湖〉焦岗湖〉沱湖〉瓦埠湖〉城东湖〉花园湖。不同湖泊沉积物总氮、总磷背景值差异很大。通过对100个湖泊表层沉积物TN、TP的频度分析发现,沉积物营养盐含量上25%点位对应的TP质量浓度398.51mg·kg-1,TN质量浓度为1106.24 mg·kg-1,沉积物营养盐含量下25%点位对应的TP质量浓度664.58 mg·kg-1,TN质量浓度为2916.66 mg·kg-1。通过互相之间的比较分析,推荐采用背景值比较法确定的各湖泊沉积物总氮、总磷背景值均值与频度分步法25%点位对应的总氮值和40%点位对应的总磷值作为东部浅水湖泊沉积物总氮、总磷基准阈值。因此,?     

太湖表层沉积物中多磷酸盐检出的环境意义

在氮限制型富营养化湖泊中,沉积多磷酸盐(Poly-P)可以用来示踪营养盐磷的输入和湖泊的富营养化过程。太湖是一个典型的磷限制型富营养化湖泊,通过对太湖表层沉积物中总有机碳(TOC)、总氮(TN)、总磷(TP)、氢氧化钠可提取磷(NaOH-P)以及Poly-P的提取分析,初步探讨了太湖营养盐磷输入的历史记录,并揭示了该湖Poly-P的主要来源和保存机制。太湖Poly-P的质量浓度较低,变化范围为0.004~0.065mg·g-1。NaOH-P占TP组成的22%,是太湖沉积物总磷的主要组成部分之一。结果显示,在湖泊水体藻类生物量较大和NaOH-P是沉积物TP重要组成部分的磷限制型湖泊中,Poly-P也是沉积物磷汇组成的一个重要部分,同时还是一个可以反映由人为磷输入增大导致湖泊富营养化程度加剧的敏感指标。     

不同类型湖泊沉积物碱性磷酸酶活性时空差异特征分析

沉积物是湖泊营养盐重要的蓄积库,是湖水氮、磷元素的重要来源之一.碱性磷酸酶是一种专一性的磷酸酯水解酶,可以催化所有的磷酸酯水解反应和磷酸基团的转移反应,在沉积物的生物释磷过程中具有关键作用.研究湖泊碱性磷酸酶的活力及其对湖泊营养盐的影响,对于控制内源磷污染,防治水体富营养化具有重要的意义.     

长江流域湖泊湿地生态环境状况分析

在对长江流域湖泊湿地长期调查或考察的基础上,首先明确了长江流域湖泊湿地的战略地位,进而提出其当前存在的人水争地等主要生态环境问题。在此基础上从气候变化以及人类活动的角度对湖泊湿地在调蓄洪水、净化水质、保护湖泊生物多样性等方面的功能和关系作了探讨。认为随着经济发展和人口的增加,人水争地矛盾将愈来愈突出,加之种种因素造成的生态环境破坏,流域湖泊湿地生态环境压力将愈来愈大,并业已成为国民经济发展的制约因素。文章可为寻求长江流域湖泊湿地治理及管理对策提供基础资料或信息。     

通讯

浅水富营养化湖泊巢湖近百年重金属污染的沉积物记录 湖泊沉积物中重金属的富集主要与流域的人类活动密切相关,其剖面分布反映了流域人类活动与自然环境相互作用的过程,是评价湖泊环境现状及演变趋势、识别流域主要环境问题的一个重要标志．中国湖泊历史监测数据稀缺,利用高分辨率沉积柱状样品的分析,可以重建过去湖泊重金属的污染历史,     

洱海湖心区沉积柱芯营养盐垂向分布及时间演化特征

连续的沉积物记录为研究湖泊富营养化的长期过程提供了可能。分析了洱海湖中心沉积柱的营养盐浓度垂向分布和沉积物年代记录,并结合湖心水质变化情况,研究了洱海沉积物营养盐的时间演化特征及生态意义。结果显示:Cal.AD 1960年以前,洱海沉积物营养盐稳定在较低水平,总有机碳(TOC)平均质量分数为1.45%,总氮(TN)平均质量分数为0.20%,总磷(TP)质量分数低于1 000 mg·kg~(-1);Cal.AD 1960年以后,TOC和TN质量分数均急剧升高,尤其在1990年之后呈直线上升态势,最高值分别为5.8%和0.84%,TP质量分数从1 000 mg·kg~(-1)。左右直线上升至1 345 mg·kg~(-1),反映了洱海近几十年来的人为富营养化加剧过程。沉积物TP与TOC、TN呈极显著正相关(P=0.001),TOC与TN的Pearson相关系数最大。洱海沉积物的TOC/TN比值总体比较稳定,数值在5.8~11.5之间波动,反映出这3种营养物质的藻类同源性。沉积物的营养物累积过程伴随水质变化呈不断恶化趋势,1990年后沉积物营养盐的时间演变规律与湖心区水质随时间的变化趋势基本一致。洱海表层沉积物TN、TP浓度明显高于东部平原湖区的湖泊,其营养盐内源负荷不容忽视。与同地区湖泊相比,沉积物TN浓度水平与抚仙湖和滇池相当,而TP浓度明显低于这两个湖泊,说明洱海沉积物对P仍具有较强的吸附容量及潜在缓冲能力。     

湖泊内源氮磷污染分析方法及特征研究进展

湖泊的内源氮磷污染已成为湖泊富营养化治理的一大难题.本文总结了沉积物中氮磷赋存形态、沉积物-水界面氮磷迁移释放行为和沉积物中氮磷的生物有效性三方面的研究进展,提出了目前研究存在的问题,并对未来发展趋势和研究方向进行了展望,以期为湖泊内源氮磷污染机理分析和湖泊富营养化治理控制技术提供参考.     

Integrated model projections of climate change impacts on a North American lake

Climate change is likely to impact terrestrial and aquatic ecosystems via numerous physical and biological mechanisms. This study outlines a framework for projecting potential impacts of climate change on lakes using linked environmental models. Impacts of climate drivers on catchment hydrology and thermal balance in Onondaga Lake (New York State) are simulated using mechanistic models HSPF and UFILS4. Outputs from these models are fed into a lake ecosystem model, developed in AQUATOX. Watershed simulations project increases in the magnitude of peak flows and consequent increases in catchment nutrient export as the magnitude of extreme precipitation events increases. This occurs concurrently with a decrease in annual stream discharge as a result of increased evapotranspiration. Simulated lake water temperatures increase by as much as 5 °C during the 2040-2069 time period, accompanied by a prolonging of the duration of summer stratification. Projected changes include shifts in the timing of nutrient cycling between lake sediments and water column. Plankton taxa projected to thrive under climate change include green algae and Bosmina longirostris. Responses for species at higher trophic levels are mixed. Benthic macroinvertebrates may either prosper (zebra mussels) or decline (chironomids), while fish (e.g., gizzard shad) exhibit high seasonal variability without any clear trend.     

Macrophyte species composition and structure along littoral region in relation to limnological variables of a tropical wetland ecosystem

The composition and structure of macrophyte communities of the littoral region of Bhindawas wetland (India) was investigated. Two hypotheses were tested: (1) if limnological variables such as water chemistry and soil parameters are important determinants of species composition and abundance and (2) what is the variance in species richness and composition within the wetland. Twenty-eight macrophyte species belonging to 17 different families were identified with relatively low species diversity and richness (H′?=?2.09; Margalef index?=?1.12). Eichhornia crassipes, attained the highest relative frequency (22.69%), followed by Salvinia natans, Paspalum paspaloides, Phragmites karka, Cynodon dactylon and Cyperus alopecuroides. The first and second axis of CCA ordination explained 38.4% and 28.5% of the total variance of species–limnological variables relationship, respectively. Water-related variables (dissolved oxygen, pH and nitrate concentration) and soil nutrient factors (soil carbon and phosphorus levels) were significantly correlated to macrophyte distribution. Sampling sites formed two distinct groups based on cluster analysis, indicating varying ecological conditions. Generally, composition and abundance of macrophytes evince highly productive nature of the lake, while dominance of invasive species like E. crassipes and S. natans indicates high influence of increased nutrient levels and anthropogenic activities in the catchment on lake macrophyte composition.     

Integrating wetlands and riparian zones in river basin modelling

Wetlands, and in particular riparian wetlands, represent an interface between the catchment area and the aquatic environment. They control the exchange of water and related chemical fluxes from the upper catchment area to surface waters like streams and lakes. Their influence on water and nutrient balances has been investigated mainly at the patch scale. In this study an attempt was made (a) to integrate riparian zones and wetlands into eco-hydrological river basin modelling, and (b) to quantify the impacts of riparian wetland processes on water and nutrient fluxes in a meso-scale catchment located in the northeastern German lowland. The investigation was performed by analysing hydro-chemical field data and applying the eco-hydrological model SWIM (Soil and Water Integrated Model), which was extended to reproduce the relevant water and nutrient flows and retention processes at the catchment scale in general, and in riparian zones and wetlands in particular. The main extensions introduced in the model were: (1) implementation of daily groundwater table dynamics at the hydrotope level, (2) implementation of water and nutrient uptake by plants from groundwater in riparian zones and wetlands, and (3) assessment of nutrient retention in groundwater and interflow. The simulation results indicate that wetlands, though they represent relatively small parts of the total catchment area, may have a significant impact on the overall water and nutrient balances of the catchment. The uncertainty of the simulation results is considerably high, with the main sources of uncertainty being the model parameters representing the geo-hydrology and the input data for land use management.     

Watershed land use effects on lake water quality in Denmark

Mitigating nutrient losses from anthropogenic nonpoint sources is today of particular importance for improving the water quality of numerous freshwater lakes worldwide. Several empirical relationships between land use and in-lake water quality variables have been developed, but they are often weak, which can in part be attributed to lack of detailed information about land use activities or point sources. We examined a comprehensive data set comprising land use data, point-source information, and in-lake water quality for 414 Danish lakes. By excluding point-source-influenced lakes (n = 210), the strength in relationship (R2) between in-lake total nitrogen (TN) and total phosphorus (TP) concentrations and the proportion of agricultural land use in the watershed increased markedly, from 10-12% to 39-42% for deep lakes and from 10-12% to 21-23% for shallow lakes, with the highest increase for TN. Relationships between TP and agricultural land use were even stronger for lakes with rivers in their watershed (55%) compared to lakes without (28%), indicating that rivers mediate a stronger linkage between landscape activity and lake water quality by providing a "delivery" mechanism for excess nutrients in the watershed. When examining the effect of different near-freshwater land zones in contrast to the entire watershed, relationships generally improved with size of zone (25, 50, 100, 200, and 400 m from the edge of lake and streams) but were by far strongest using the entire watershed. The proportion of agricultural land use in the entire watershed was best in explaining lake water quality, both relative to estimated nutrient surplus at agricultural field level and near-lake land use, which somewhat contrasts typical strategies of management policies that mainly target agricultural nutrient applications and implementation of near-water buffer zones. This study suggests that transport mechanisms within the whole catchment are important for the nutrient export to lakes. Hence, the whole watershed should be considered when managing nutrient loadings to lakes, and future policies should ideally target measures that reduce the proportion of cultivated land in the watershed to successfully improve lake water quality.     

Control concept and countermeasures for shallow lakes’ eutrophication in China

Research on lake eutrophication in China began in the early 1970s, and many lakes in China are now known to be in meso-eutrophic status. Lake eutrophication has been showing a rapidly increasing trend since 2000. Investigations show that the main reasons for lake eutrophication include a fragile lake background environment, excessive nutrient loading into lakes, excessive human activities, ecological degeneration, weak environmental protection awareness, and lax lake management. Major mechanisms resulting from lake eutrophication include nutrient recycling imbalance, major changes in water chemistry (pH, oxygen, and carbon), lake ecosystem imbalance, and algal prevalence in lakes. Some concepts for controlling eutrophication should be persistently proposed, including lake catchment control, combination of pollutant source control with ecological restoration, protection of three important aspects (terrestrial ecology, lake coast zone, and submerged plant), and combination of lake management with regulation. Measures to control lake eutrophication should include pollution source control (i.e., optimize industrial structural adjustments in the lake catchment, reduce nitrogen and phosphorus emission amounts, and control endogenous pollution) and lake ecological restoration (i.e. establish a zone-lake buffer region and lakeside zone, protect regional vegetation, utilize hydrophytes in renovation technology); countermeasures for lake management should include implementing water quality management, identifying environmental and lake water goals, legislating and formulating laws and regulations to protect lakes, strengthening publicity and the education of people, increasing public awareness through participation in systems and mechanic innovations, establishing lake region management institutions, and ensuring implementation of governance and management measures.     

Use of thermodynamic indices as ecological indicators of the development state of lake ecosystems: 2. Exergy and specific exergy indices

The effectiveness of exergy and specific exergy indices as ecological indicators of the trophic state of lake ecosystems is here tested on a small homogeneous set of shallow lakes which, in spite of their similar nutrient concentrations, morphology and hydrology, show a different trophic state and structure, species composition and abundance. The findings reveal that exergy and specific exergy indices have good negative correlation with phytoplankton biomass and Carlson's trophic state index (TSI) and strong positive correlation to water transparency (the relationship between exergy and eutrophication is clearer if the exergy refers to surface units, rather than volume units) and, hence, that they may be used as ecological indicators of the trophic state of lake ecosystems. The relationship between the responses of the thermodynamic approach and other conventional trophic classification methods (Vollenweider's eutrophication model based on phosphorus loading, the Hillbrich-Ilkowska method and the Vollenweider–OECD classification criterion) previously applied to Lake Trasimeno, was also investigated. The decreasing trend of exergy and specific exergy indices with eutrophication increase appears to be essentially due to the change in species composition and trophic structure, rather than to a different trophic potentiality of the ecosystems investigated. Concerning the identification of the environmental factors responsible for exergy and specific exergy trends, the coherence of the correlation structure between water depth, TSI, exergy and specific exergy indices, suggests that the lake's mean water depth plays a significant role in determining the changes in trophic structure and state (and consequently in exergetic indices) within the set of lakes examined and emphasises the importance of lake morphology in the development and ageing of lake ecosystems.     

杭州西湖湖湾生物硅沉积测定与营养演化的过程

选择杭州西湖3处湖湾——茅家埠、乌龟潭、浴鹄湾作为研究对象,通过3处湖湾多点浅钻的表层沉积物生物硅质量分数测试,通过底泥分析西湖疏浚与水环境治理措施的效果。研究发现：对照西湖沉积速率（4mm／a）,3处湖湾表层沉积物中生物硅质量分数高低依次为茅家埠、乌龟潭与浴鹄湾。近10年来不同湖湾沉积物中生物硅沉积含量相差较大,这一时期正对应着西湖综合环境整治工程。对西湖3个湖湾表层沉积物中生物硅质量分数研究表明：西湖水体中的氮、磷、硅促进了硅藻的生长与硅的消耗,不同湖湾之间生物硅沉积存在着明显差异,这可能与人类活动的影响差异有关。     

Exploitation and destabilization of a warm, freshwater ecosystem through engineered hydrological change

Exploitation of freshwater resources is having catastrophic effects on the ecological dynamics, stability, and quality of those water resources on a global scale, especially in arid and semiarid regions. Lake Kinneret, Israel (the Biblical Sea of Galilee), the only major natural freshwater lake in the Middle East, has been transformed functionally into a reservoir over the course of approximately 70 years of hydrological alterations aimed mostly at producing electrical power and increasing domestic and agricultural water supply. Historical changes in lake chemistry and biology were reconstructed using analysis of sedimentary nutrient content, stable and radioisotope composition, biochemical and morphological fossils from algae, remains of aquatic invertebrates, and chemical indices of past light regimes. Together, these paleolimnological analyses of the lake's bottom sediments revealed that this transformation has been accompanied by acceleration in the rate of eutrophication, as indicated by increased accumulation rates of phosphorus, nitrogen, organic matter, phytoplankton and bacterial pigments, and remains of phytoplankton and zooplankton. Substantial increases in these indices of eutrophication coincide with periods of increased water-level fluctuations and drainage of a major upstream wetland in the early to middle 20th century and suggest that management of the lake for increased water supply has degraded water quality to the point that ecosystem stability and sustainability are threatened. Such destabilization may be a model for eutrophication of freshwater lakes in other arid regions of the world in which management emphasizes water quantity over quality.     

Implementation of ecological modeling as an effective management and investigation tool: Lake Kinneret as a case study

The need for scientifically based management of lakes, as key water resources, requires the establishment of quantitative relationships between in-lake processes responsible for water quality (WQ) and the intensity of major management measures (MM, e.g. nutrient loading). In this paper, we estimate the impact of potential changes in nutrient loading on the Lake Kinneret ecosystem. Following validation of the model against a comprehensive dataset, we applied an approach that goes beyond scenario testing by linking the lake ecosystem model DYRESM–CAEDYM with a set of ecosystem variables included in a pre-assessed system of water quality indices. The emergent properties of the ecosystem predicted from the model simulations were also compared with lake data as a form of indirect validation of the model. Model output, in good agreement with lake data, indicated differential effects of nitrogen and phosphorus nutrient loading on concentrations, and major in-lake fluxes, of TN and TP, and dynamics and algal community structure. Both model output and lake data indicated a strong relationship between nitrogen loading and in-lake TN values. This relationship is not apparent for phosphorus and only a weak relationship exists between phosphorus loading and in-lake TP. The modeling results, expressed in terms of water quality, allowed establishment of critical/threshold values for the nutrient loads. Implementation of the ecological modeling supplemented with the quantified set of WQ indices allowed us to take a step towards establishment of the association between permissible ranges for water quality and major management measures, i.e. towards sustainable management.     

河北省衡水湖沉积物中汞的分布特征及生态风险

衡水湖是华北平原上第一个国家级内陆淡水湖泊湿地类型的自然保护区,为了解衡水湖沉积物中汞的分布特征及生态风险,于2013年8月在衡水湖采集了5根柱状沉积物,对其中的总汞、甲基汞、孔隙水溶解态汞、有机质、pH以及含水率进行了分析。结果表明,衡水湖沉积物中总汞的平均含量为22.5 ng·g-1,低于全国及河北省表层土壤背景值。但表层沉积物汞含量明显高于底层,说明近年来的外源汞输入对湖泊汞负荷产生了一定影响,且靠近湖泊东部106国道的采样点汞含量明显高于湖泊中西部的采样点,暗示交通运输等人为活动是该湖泊的一个重要汞输入源。利用潜在生态危害指数法进行评估,显示汞的生态风险较低,说明现阶段衡水湖的沉积物汞浓度不会对生态环境产生不利影响。