Long-term dynamics of phosphorus in the Narochanskie Lakes and factors determining it

The Narochanskie Lakes (Batorino, Myastro, and Naroch) (Belarus) are a focus of many-year hydroecological studies. The modern evolution of the ecosystem of the lakes includes four stages: anthropogenic eutrophication in the 1970s, de-eutrophication because of nature protection measures in their drainage area in the 1980s, benthification because of invasion of mollusk-filterer Dreissena polymorpha Pallas in the 1990s, and the present-day state. Retrospective analysis of many-year dynamics of total phosphorus (1978–2010) in water of the Narochanskie Lakes is given for different stages of their ecosystems restructuring. The complex response of water bodies comprising a single ecosystem to external impacts is described and its causes are discussed.     

Stable isotopes in the source waters of the Yamuna and its tributaries: seasonal and altitudinal variations and relation to major cations

Water samples from the Yamuna and its tributaries, one of the major river systems draining the Himalaya, have been analysed for their stable oxygen and hydrogen isotopes during three seasons (summer, monsoon and post‐monsoon). The data show clear seasonal and altitudinal variations; waters from higher altitudes and those collected during monsoon season are characterized by relatively depleted isotopic composition. Regression analysis of δD–δ¹⁸O data of samples collected during summer and monsoon seasons shows that the slope of the best‐fit lines are nearly identical to those of precipitation at New Delhi for the same period. The similarity in their slopes suggests that the isotopic composition of precipitation contributing water to these rivers are reasonably well preserved in both monsoon and non‐monsoon seasons, however, during the non‐monsoon period both rainfall and river waters carry signatures of evaporation. The ‘deuterium excess’ in river waters during the three seasons though overlap with each other, the values during October are higher. This can be understood in terms of recycled moisture contributions to precipitation. The ‘altitude effect’ for δ¹⁸O in these waters is determined to be 0·11‰ per 100 m, a factor of about two less than that reported for the Ganga source waters from similar altitudinal range. The variability in altitude effects in rivers draining the Himalaya seems to be controlled by the ‘amount effect’ associated with the monsoon. The significant spatial variability in altitude effect in these river basins, which are a few hundred kilometers apart, suggests that reconstruction of palaeoelevation in the Himalaya, based on δ¹⁸O‐altitude gradients, would depend critically on its proper assessment in the region. This study has established a relationship between total cation abundance and δ¹⁸O in waters of the Yamuna mainstream; total cations (corrected for cyclic components) double for a 1·4 km decrease in altitude as the Yamuna flows downstream. Copyright © 2002 John Wiley & Sons, Ltd.     

Seasonal variations in the trophic structure of phyto-and zooplankton communities in lakes in different trophic states

A number of environmental factors are important in regulating the trophic structure of plankton. Increased nutrient supply results in an explosive development of small algae and herbivorous zooplankton. In the eutrophic lakes (Greifensee, Hallwilersee) several algal community collapses occur each year as a consequence of the grazing habit of the zooplankton, although only the grazing phase in May/June results in a ‘clear water period’. Vertical mixing influences the zooplankton community by reactivating the resting stages of predatory copepods. Predation phases can only be observed in lake Lucerne, where the hypolimnion ist deep and aerobic. Well balanced relationships between the different trophic levels are restricted to the phases with growth limiting conditions.     

Measurements and significance of bio-optical parameters for remote sensing in two subalpine lakes of different trophic state

Bio-optical measurements were carried out on eutrophic Lake Zug and oligotrophic Lake Lucerne, to provide data and models for thein situ calibration of multispectral imagery collected in 1991, during an AVIRIS flight over Central Switzerland.The results indicate that Secchi depth, chlorophyll and total suspended solid concentrations, vertical extinction coefficient, absorption coefficient and irradiance reflectance in the PAR region can be used to discriminate between the two lakes. Dissolved organics concentration, scattering and total attenuation coefficients estimates, as well as backscattering probability, are less acceptable, because of instrumental limitations.Relationships between optical and water quality parameters were investigated and found to behave according to accepted theoretical frameworks. Both lakes exhibited vertical and horizontal heterogeneities in chlorophyll and turbidity, and had contrasting mean bio-optical characteristics: although suspended solid concentrations were similar, transparency was lower in Lake Zug, but reflectance was substantially higher in Lake Lucerne. Water colour determined by chromaticity analysis was blue-green in Lake Lucerne and green in Lake Zug.Reflectance spectra simulated through a three-component optochemical model did not completely match those derived fromin situ measurements, because of lack of site-specific optical cross-sections for suspended minerals and dissolved organics.The monitoring of water quality in subalpine lakes by remote sensing, both with present and future technology, is discussed and considered as possible, provided that their optical behaviour is known, and preferably expressed by a valid optochemical model.     

Seasonal variations and trophic ecology of microzooplankton in the southeastern Arabian Sea

The seasonal ecological response of microzooplankton in the southeastern Arabian Sea is presented. During the spring intermonsoon period, stratification and depletion of nitrate in the surface waters (nitracline was at 60 m depth) cause low integrated chlorophyll a (av. 19±11.3 mg m⁻²) and primary production (av. 164±91 mgC m⁻² d⁻¹). On the other hand, nutrient enrichment associated with coastal upwelling and river influx during the onset and peak summer monsoon resulted in high integrated chlorophyll a (av. 21±6 mg m⁻² and av. 29±21 mg m⁻², respectively) and primary production (av. 255±94 mgC m⁻² d⁻¹ and av. 335±278 mgC m⁻² d⁻¹, respectively). During all three periods, diazotropic cyanobacterium Trichodesmium erythraeum dominated in the nutrient depleted surface waters. A general increase in abundance of larger diatoms was evident in the surface waters of the inshore region during monsoon periods. The microzooplankton abundance was found to be significantly higher during the spring intermonsoon (av.241±113×10³ ind m⁻²) as compared to onset of summer monsoon (av. 105±89×10³ ind m⁻²) and peak summer monsoon (av.185±175×10³ ind m⁻²). Microzooplankton community during the spring intermonsoon was numerically dominated by ciliates while heterotrophic dinoflagellate was the dominant ones during the monsoon periods. The high abundance of ciliates during the spring intermonsoon could be attributed to the stratified environmental condition prevailed in the study area which favors high abundance of smaller phytoplankton and cyanobacteria, the most preferred food of ciliates. On the other hand, the dominance of heterotrophic dinoflagellates during the monsoon periods could be linked to their ability to graze larger diatoms which were abundant during the monsoon periods. The overall results show low abundance of microzooplankton in the eastern Arabian Sea during the monsoon periods mainly due to a decline in ciliates abundance. This decline during the monsoon periods could be the result of (a) low abundance of smaller phytoplankton and (b) high stock of mesozooplankton predators (av. 245 ml 100 m⁻³).     

Many-year level variations in the Great Lakes of Eurasia and North America

Regularities in the secular variations of water level in the Great Lakes of Eurasia and North America under natural climate and anthropogenic impacts are studied.     

Current state of heterotrophic bacterioplankton in the Kosinskie Lakes

From December 2009 to December 2010, the total abundance of bacteria, the abundance of bacteria with electron transport chain, the abundance of viable saprotrophic bacteria, and the concentration of chlorophyll a were studied in water samples from lakes Svyatoe, Beloe, and Chernoe in Kosino-Ukhtomskoe district, Moscow City. The abundance of bacteria with active electron transport chain (CTC+bacteria) and its seasonal variations in Kosinskie Lakes are studied for the first time. Those lakes were found to contain well-developed and actively functioning heterotrophic bacterioplankton, the abundance of which have increased considerably since the 1930s–1940s. The seasonal dynamics of bacterioplankton has also changed. The largest absolute abundance of CTC+bacteria in lakes Svyatoe and Beloe was recorded in summer and autumn (from August to November). The abundance peak of CTH+bacteria in Lake Svyatoe was recorded in September and that in Lake Beloe, in October. The abundance of CTC+bacteria also showed a peak in April. In Lake Chernoe, the abundance of CTC+bacteria was much less than in lakes Svyatoe and Beloe; its maximums were recorded in December 2009 and April 2010. The share of CTC+bacteria in the total abundance of bacteria was 2.4–19.2% in Lake Svyatoe, 1.8–63.0% in Lake Beloe, and 0.96–22.5% in Lake Chernoe. Significant correlations were found to exist in all three lakes between the abundance of active bacterioplankton fraction and chlorophyll a content of water.     

Chemical composition and the nitrogen-regulated trophic state of Patagonian lakes

Chemical composition and nutrient concentrations of 39 relatively poorly known Patagonian lakes (38–50°S and from 70° to 68°W) are described and analysed using principal component analysis (PCA). The general relationships between nutrients (total phosphorus, bioavailable phosphorus and dissolved inorganic nitrogen) and plankton biomass are examined.We seek to demonstrate that the extreme oligotrophy characterising many lakes and reservoirs of the Argentine Patagonian region of South America owes more to nitrogen deficiency than to a shortage of available phosphorus. The data show a range of trophic conditions with variable water chemistry characteristics.The first two axes of the PCA ordination explain most of the variance (63%). The first component of the variance in the environmental data is a trophic gradient, with positive correlations with the concentrations of nutrients (TP, SRP, DIN) and electrical conductivity and a negative correlation with transparency. For all the reservoirs considered, the calculated annual, summer and winter chlorophyll-a carrying capacities of the available phosphorus were consistently and significantly (P<0.05) in excess of observations but maximum chlorophyll-a values correlate with DIN availability. Indeed the chlorophyll-a carrying capacities, as an index of the resource-sustainable maximum biomass, of the available nitrogen gives a better predictive yield relationship than does P. Our findings are remarkable in so far as the general expectation that dinitrogen-fixing phytoplankton should thrive in the absence of dissolved inorganic nitrogen, at least to the supportive limits of the available phosphorus, is unfulfilled.     

Long-term variations in the earth's motion and crustal movements

Astronomical observations of time and latitude providing precise information on the motion of the earth as a whole (rotation and polar motion) point to the existence of secular and periodical variations due to tidal forces and geophysical and meteorological causes.Together with these variations, there is also evidence that the earth's crust is wandering as a result of the action of different forces, and the mean latitudes and longitudes of the observatories vary because of continental and/or local displacements.In this paper an analysis of a long series of latitude and time astronomical observations is carried out in order to investigate their long-term variations, and an important result is found: there is significant evidence for the existence of a relationship between the rotational accelerations of the earth and the variation in the positions of the mean rotation pole over periods of about thirty years. This result is discussed from the viewpoint of a deformable earth and/or crustal movements.     

Long-term variations in geomagnetic and solar activities and secular variations of the geomagnetic field components

Summary After the removal of the eleven-year periodicity, long-term patterns of the aa indices of geomagnetic activity and of Wolf's sunspot numbers are defined. The positions of maxima and minima exhibit the same regularities as the secular variations of the geomagnetic filed components. This result is associated with the motion of the Sun round the barycentre of the solar system.Presented at symposium Planet 88, Tihany, September 1988.     

The pattern characteristics of the tendency variations of earth resistivity and its relation to earthquakes

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太湖不同富营养水平湖区轮虫季节变化的比较

2003年10月-2004年9月对太湖不同富营养水平湖区(太湖大太湖湖区、梅梁湾和五里湖)轮虫的季节变化进行了研究.五里湖营养水平最高,太湖大太湖湖区最低;轮虫的种类数、数量和生物量都是五里湖最高,太湖大太湖湖区最低.回归分析表明,轮虫数量与总氮和叶绿素a浓度呈显著正相关;轮虫生物量与叶绿素a浓度呈极显著正相关.结果表明,太湖三个湖区轮虫群落结构显著不同,同时表明太湖水体富营养化对轮虫的群落结构有明显的影响.     

Radioactive heat production in rocks and its relation to other petrophysical parameters

Summary Radioactive heat productionA is a scalar and isotropic petrophysical property independent of in situ temperature and pressure. Its value is usually expressed in HGU units (1 HGU=10^–13 cal/cm³ sec) and depends on the amounts of uranium, thorium and potassium.A varies with rock type over several orders of magnitude and reflects the geochemical conditions during rock formation (magmatic differentiation, sedimentation or metamorphism).In order to assign realistic thermal parameters to deeper-seated rocks correlations with seismic velocity (which can be determined from the surface) have been looked for. In the range characteristic for crystalline rocks of the crust (5–8 km/sec)A is strongly correlated with density and compressional wave velocityv _p:A decreases with increasingv _p orp. From this relationship it is now possible to estimate heat production values for any particular layer of a crustal section from measured seismic velocities. Contrary to earlier belief there is, as shown by experimental determinations, no correlation between heat productionA and thermal conductivityK in igneous and metamorphic rocks. In sediments however, especially in sand/shale sequences, a correlation betweenK andA is most likely: increasing clay mineral content, characterized by increasingA, causes the decrease ofK in these rocks.Contribution No. 111, Institute of Geophysics, Swiss Federal Institute of Technology, Zurich, Switzerland.     

The northern annular mode in summer and its relation to solar activity variations in the GISS ModelE

The northern annular mode (NAM) has been successfully used in several studies to understand the variability of the winter atmosphere and its modulation by solar activity. The variability of summer circulation can also be described by the leading empirical orthogonal function (EOF) of geopotential heights. We compare the annular modes of the summer geopotential heights in the northern hemisphere stratosphere and troposphere in the Goddard Institute for Space Studies (GISS) ModelE with those in the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis. In the stratosphere, the summer NAM obtained from NCEP/NCAR reanalysis as well as from the ModelE simulations has the same sign throughout the northern hemisphere, but shows greater variability at low latitudes. The patterns in both analyses are consistent with the interpretation that low NAM conditions represent an enhancement of the seasonal difference between the summer and the annual averages of geopotential height, temperature and velocity distributions, while the reverse holds for high NAM conditions. Composite analysis of high and low NAM cases in both model and observation suggests that the summer stratosphere is more “summer-like” when the solar activity is near a maximum. This means that the zonal easterly wind flow is stronger and the temperature is higher than normal. Thus increased irradiance favors a low summer NAM. A quantitative comparison of the anti-correlation between the NAM and the solar forcing is presented in the model and in the observation, both of which show lower/higher NAM index in solar maximum/minimum conditions. The temperature fluctuations in simulated solar minimum conditions are greater than in solar maximum throughout the summer stratosphere.The summer NAM in the troposphere obtained from NCEP/NCAR reanalysis has a dipolar zonal structure with maximum variability over the Asian monsoon region. The corresponding EOF in ModelE has a qualitatively similar structure but with less variability in the Asian monsoon region which is displaced eastward of its observed position. In both the NCEP/NCAR reanalysis and the GCM the negative anomalies associated with the NAM in the Euro-Atlantic and Aleutian island regions are enhanced in the solar minimum conditions, though the results are not statistically significant.     

岩浆活动与构造应力的相互作用及其与火山活动状态的关系

本文考虑一个包含岩浆囊和火山隆起的三维黏弹性地壳有限元模型,通过数值模拟的方法揭示了岩浆活动与构造应力之间的相互作用.首先,在底部岩浆的持续补给作用下,总结了火山地表形变、应力大小和岩浆囊过剩压力在岩浆补给不同状态下的特征和表象;同时本文研究了构造应力场变化对火山岩浆囊应力的影响,发现10 MPa的板块应力作用能够引起岩浆囊内±1.2~1.6 MPa的压力变化,这个量级足以对岩浆囊形成扰动,从而引发各种火山活动.     

The ring current injection function and its relation to interplanetary parameters

Summary The linear regression equations, reflecting the relationship between the energy injection rate into the ring current and various combinations of geoeffective solar wind and IMF parameters during the main phase of a magnetic storm, have been derived. The highest values of the correlation coefficient (r>0·8) were obtained for the relationships between the energy injection rate F _exp and the solar wind electric field, especially when the high-frequency part of its variations was taken into account (E_y and F _mod ), and also for F _exp vs F _MUR , which was introduced by Murayama earlier.

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Резюме Получены урaвненuя лuнеŭноŭ ре?rt;рессuu, связывaющuе скоросmь nосmуnленuя энер?rt;uu в кольцевоŭ mок с рaзнымu комбuнaцuямu ?rt;еоэффекmuвных naрaмеmров солнечно?rt;о веmрa u межnлaнеmно?rt;о мa?rt;нumно?rt;о nоля. Нauболее высокuе коэффuцuенmы корреляцuu (r>0,8) хaрaкmерны ?rt;ля сооmношенuŭ меж?rt;р вычuсленноŭ nо нaземным нa?rt;лю?rt;енuям мa?rt;нumно?rt;о nоля кольцево?rt;о mокa функцuеŭ uнжекцuu Ф _exp u элекmрuческuм nолем солнечно?rt;о веmрa, в чaсmносmu nрu включенuu высокочaсmоmноŭ чaсmu е?rt;о вaрuaцuŭ (Е_y u Ф _mod сооmвеmсmвенно), a maкже функцuеŭ Ф _MUR , вве?rt;енноŭ Мурaямa рaннее.

     

我国常用湖泊营养状态指数研究进展与展望

湖泊(包括自然湖泊和人工水库)富营养化已成为世界性的环境问题,营养状态指数是目前最流行的富营养化水平量化方法。然而,不同营养状态指数的基本逻辑和适用水体等方面存在明显差异,不当选取可能会造成营养水平和相关水华风险的错误估计,并引发湖泊保护和修复措施的错位。鉴于此,本文对我国常用营养状态指数的构建思路、共性和差异以及不确定性来源等进行了综述。总体来看,营养状态指数基本构建思路分3种:1) Carlson指数型(如TSI),以透明度(SD)为核心参数,使用SD的2倍变化对应指数的10分差值,假定SD 为64 m时记为指数值0分;2)改良TSI指数型(如TSIm),以叶绿素a(Chl.a)为核心参数,使用Chl.a的2.5倍变化对应指数的10分差值,假定Chl.a 1000 μg/L对应该指数100分;3)营养足迹指数型(如TFI),该指数亦使用Chl.a指示藻类生物量,Chl.a的e倍关系对应藻类生物量的二倍变化和指数10分差值,假定Chl.a为10 μg/L时对应该指数50分。根据上述假设得出对应的基础参数评估方程,然后均以基础参数(SD或Chl.a)与衍生参数间的经验方程 “直接替换”获得衍生参数的评估方程。如上可知,营养状态指数均体现了数值增大表征藻类初级生产力和伴随的水华风险提高的共性,同时本文也从:1)数据集属性和基础指标评估方程获取的方法;2)衍生指标评估方程获取的统计原理;3)分项指标的权重设置方式3个方面分析营养状态指数之间的差异性。未来展望方面,首先,鉴于当前营养状态指数均属于通用性指数,因而建议未来基于上述3种基本类型开发因地制宜的营养状态指数,实现湖泊藻类生产力和水华风险的精准指示;其次,营养状态指数的生态学依据是藻类限制因子理论,营养状态指数各分项指标(即基于总氮、总磷、SD和Chl.a)的差异可以指示初级生产力的限制因子,建议未来开展营养状态指数分项指标差异机制研究,以指导藻类水华防控措施精准施策;再次,除富营养化外,湖泊生态健康受损往往也与其它压力有关,建议未来开展湖泊生态健康对富营养化和其他压力的综合响应机制研究,制定服务于湖泊生态系统健康提升的精准调控路径。本文目的并非将营养状态指数的通用属性“复杂化”,而是旨在阐明营养状态指数的“前世今生”,进而为广大湖泊富营养化相关人员使用指数时提供参考,也希望为我国湖泊营养状态精准量化、后续保护和修复措施的精准实施提供科学依据。     

Chemistry and trophic evolution of Lake Lugano in relation to nutrient budget

Chemical studies performed in the last 50 years on the northern and southern basins of Lago di Lugano are reviewed and discussed in relation to the phosphorus and nitrogen loads from the drainage area.Both basins became eutrophic in the fifties as a consequence of the dense population and industrial activity in the drainage area; the effect of these was aggravated by the meromictic condition of the layer below 100 m in the northern basin.The reduction of phosphorus loads in progress since 1976 has resulted in a significant improvement in the chemical and biological condition of the southern basin and the upper 100 m of water in the northern basin. On the other hand, the balance between dissolved oxygen and reducing substances in the northern basin is shifting toward a decrease of the net oxygen concentration, partly as a consequence of the unusually dry conditions of the last three years.A reduction in phosphorus load down to 18 and 22 t a^–1 in the northern and southern basins respectively is still necessary in order to reduce the lake phosphorus concentration to 30–35 µg O l^–1.     

Long-term variations in the biogenic matter runoff of the Dnestr River

Long-term observation data were used to carry out comparative analysis of variations in the biogenic matter runoff of the Dnestr River over a period of fifty years. Based on data of weekly monitoring in 2002–2004, annual dynamics of biogenic matter runoff was analyzed for the Dnestr River and for Dnestr Liman. It was found out that, in spite of the “buffer” role of the latter, the contribution of biogenic substances, finding their way in the sea with the Dnestr River water, to the eutrophication of the northwestern Black Sea remains appreciable (about 60 thousand ton year^?1). Dissolved organic compounds account for 70% of the present-day biogenic matter runoff of the Dnestr River.     

Characterization of the light attenuation by periphyton in lakes of different trophic state

In order to measure the attenuation of light by periphyton a method has been developed which assures that natural periphyton architecture and therefore its optical characteristics remain preserved. This method has been applied to analyze the transmittance of periphyton of four lakes of different tropic states situated in the Osterseen Lake District (Upper Bavaria, Germany). The seasonal variation of the periphyton's transmittance has been studied using standard microscope glass slides exposed 1 m beneath the water surface within macrophyte beds. The study ran from February to November 1997 in two eutrophic lakes (Lake Waschsee, Lake Sengsee) and from May to November 1997 in the meso-oligotrophic Lake Eishaussee and in the oligotrophic Lake Herrensee.Generally the exposure-period, the seasonality, and the tropic state of the habitat affected the transmittance spectra of the periphyton. In all lakes the attenuation by periphyton increased with longer colonization times but at a different time scale. The periphyton of the nutrient-rich and the nutrient-poor lakes differed clearly in composition and architecture. The eutrophic lakes were characterized by a relatively thick but loosely attached, unstable periphyton community, which was translucent to a certain degree even at the end of the growth period. The transmittance of this periphyton fluctuated considerably and high percentages of filamentous green algae in this periphyton contributed to attenuation maxima within the range 400-500 nm and 650-700 nm due to photosynthetic pigments. By contrast, the periphyton of the meso-oligotrophic and of the oligotrophic lake was quite compact and nearly impervious to light.