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1.
《Limnologica》2021
Dissolved organic carbon (DOC) is one of the most abundant fractions of organic matter in aquatic systems and plays an important role in the dynamics of aquatic environments, controlling both the penetration and the underwater light radiation climate. DOC can be photodegraded by light, thus facilitating biodegradation, especially in regions where the incidence of solar radiation is high, such as higher altitudes and lower latitudes. This study quantified the photodegradation of dissolved organic material in a natural tropical lake surrounded by native forests (Brazilian Atlantic Forest) through two experiments: i) the first experiment exposed concentrated autochthonous, allochthonous, and lake water to in situ solar radiation; ii) this experiment also exposed the same organic material to artificial UV radiation in an incubator under controlled conditions. The quality and quantity of dissolved organic carbon were measured using indices based on carbon absorbance and fluorescence spectrum. In the in situ experiment, it was observed that the DOC degradation profile of the concentrated allochthonous and autochthonous organic material were distinct from each other in the absorbance indices, and the lake water mostly resembled the latter one. On the other hand, we did not see evidence of any significant difference among treatments in the laboratory experiment. An increase in the SR index and a concomitant decrease in the fluorescence of humic compounds and SUVA254 over time were observed. In both experiments, the amount of degraded organic material over time was low and some possible explanations are discussed. 相似文献
2.
《国际泥沙研究》2022,37(5):563-575
Lacustrine sediment preserves high-resolution biogeochemical records of past variations in watershed processes controlling lake sedimentation. The current study explores historical variations in autochthonous and allochthonous sediment supplies to a large tropical freshwater lake system (Upper Lake, Bhopal) protected under the international Ramsar Convention of 2002 against anthropogenic pressures. For this purpose, multi-proxy biogeochemical data are presented for organic matter (total organic carbon, total nitrogen, phosphorous, and loss on ignition [LOI] at 550 °C), carbonate (LOI at 950 °C), lithic sediment (aluminum, titanium, iron, calcium, magnesium, sodium, potassium, manganese, zirconium, niobium, hafnium, tantalum, thorium, uranium, and rare earth elements), and anthropogenic inputs (lead) measured in a 38 cm long sediment core retrieved from the lake. In addition to the lacustrine sediment core, the samples of catchment bedrock, surface soils, major stream sediment, and eolian dust collected from the lake periphery also are analyzed. The systematic biogeochemical excursions in the upper core section (top ~8 cm) indicate increased anthropogenic inputs, watershed denudation by agricultural activities, artificially reduced fluvial sediment supply, relatively increased dust inputs and lake eutrophication in the last few decades. The current study underscores the roles of anthropogenic land-use and wetland conservation practices in the rapid alteration of autochthonous and allochthonous sediment supplies to open aquatic ecosystems. Further, rising lake eutrophication levels despite a managed reduction in allochthonous sediment supplies seem challenging to control due to dissolved nutrient supply from urban sewage discharge and runoff from agricultural land in the watershed. 相似文献
3.
Leonardo M. Furlanetto Claudio C. MarinhoCleber Palma-Silva Edélti F. AlbertoniMarcos Paulo Figueiredo-Barros Francisco de Assis Esteves 《Limnologica》2012,42(2):151-155
The vertical sediment profiles (10 cm) of the margins of three shallow subtropical lakes (Rio Grande, Brazil) with different trophic states and surrounding areas were evaluated to identify the effects of the allochthonous input on the methane concentration in the sediment. Sediment cores were collected to quantify the organic matter content (OM) and total carbon (TC), total nitrogen (TN), total phosphorous (TP) and methane (CH4) concentrations.The three lakes were distinguished according to the trophic status and classified as oligotrophic, dystrophic and eutrophic. The natural characteristics of the dystrophic and eutrophic lakes have been changed due to the allochthonous input of leaves and twigs (Eucalyptus sp.) and the excreta of birds, respectively. In the eutrophic lake, the allochthonous input contributed to high autochthonous production. The highest values of OM, TC, TN and TP were found in the superficial sediments of the dystrophic and eutrophic lakes. The accumulation of allochthonous organic matter in the littoral zone promoted changes in the vertical sediment profiles and contributed to increases in the CH4 concentrations in the sediment. 相似文献
4.
《Limnologica》2015
Submerged macrophyte detritus is a major component of the organic matter entering shallow lakes. Plant litter decomposition is a complex process that is mediated by microorganisms and some invertebrates. However, the role that aquatic organisms play in the decomposition of macrophytes in shallow subtropical lakes is unclear. This study compared the decomposition rates of Potamogeton pectinatus and Chara zeylanica in a shallow lake (southern Brazil) and assessed the fungal biomass and the macroinvertebrate community associated with the detritus. Aliquots of both species were incubated in litter bags and placed in the lake. After 1, 7, 20, 40, 60, and 80 days of incubation, one set of litter bags was removed from the lake. In a laboratory, plant material was washed for the determination of decomposition rates, chemical characterisation, and quantification of microorganisms and invertebrates. After 80 days of incubation, there was no C. zeylanica detritus, with a decomposition that was four times faster than that of P. pectinatus. The chemical composition was also different between the two detritus, with P. pectinatus showing a higher concentration of nitrogen, phosphorus, organic matter, polyphenols, and carbon. The fungal biomass was similar between the two species. In total, 7502 invertebrates belonging to 27 taxa were sampled in this study. The composition and abundance of invertebrates was different between the two species. In conclusion, the chemical structure of the macrophyte species studied was important for the microorganisms’ and invertebrates’ colonisation. In addition, leaching had an important function in the initial degradation process. 相似文献
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M. P. Petrov A. Yu. Terzhevik R. E. Zdorovennov G. E. Zdorovennova 《Water Resources》2006,33(2):135-143
The thermal structure of a shallow lake in the first month of its freeze up is shown to vary widely from year to year. The rate of temperature increase at different horizons of the water mass in early winter is evaluated, and warming of shallow and deep-water areas in the lake are shown to be uneven. The distribution of near-bed temperature as a function of water depth in the first weeks of freeze up features wide variations, though this relationship becomes more regular over time. Estimates of the effective thermal diffusivity are given for different seasons. The main periods in the variations in the heat content of water column in early winter are estimated. 相似文献
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8.
《Limnologica》2021
Inlay Lake is the second largest natural lake in Myanmar. Located in Shan State, in the eastern part of the country, it is a known biodiversity hotspot. The lake is negatively affected by an increasing local human population and rapid growth in both agriculture and tourism. In recent decades, several studies have listed faunistic and floristic groups in Inlay Lake, but there is still a general lack of knowledge about the aquatic macrophyte and phytoplankton community composition and abundance, and their interactions. To fill this knowledge gap, field surveys of biological and physical and chemical parameters were carried out in the period 2014–2017. They show that Inlay Lake is a shallow, clear water and calcareous lake, with nutrient concentrations indicating mesotrophic-eutrophic conditions. However, close to the shore, nutrient concentrations are generally higher, reflecting pollution from inflowing rivers, shoreline villages and floating gardens. Both the richness and abundance of aquatic macrophytes in Inlay Lake were high, with several species forming extensive stands in most of the lake over the whole survey period. Total phytoplankton and cyanobacterial biomass were low, but cyanobacteria included toxin-producing strains of Microcystis, suggesting that cyanobacterial and total phytoplankton biomass need to be kept low to avoid potentially harmful cyanobacterial blooms. Submerged macrophyte abundance and phytoplankton biomass were inversely correlated in the heavily vegetated northern lake area. Our survey suggests a great importance of the submerged macrophytes to the general water quality and the clear water state in Inlay Lake. Maintaining high macrophyte abundances should therefore be a goal in management strategies, both for Inlay Lake and other lakes in Myanmar. It is highly desirable to include macrophytes and phytoplankton in the lake monitoring in Myanmar. 相似文献
9.
A. Yu. Terzhevik N. I. Pal’shin S. D. Golosov R. E. Zdorovennov G. E. Zdorovennova A. V. Mitrokhov M. S. Potakhin E. A. Shipunova I. S. Zverev 《Water Resources》2010,37(5):662-673
Long-term observational data on a small, shallow Lake Vendyurskoe (Karelia) were used to analyze the space and time dissolved-oxygen
dynamics in winter. Biochemical consumption was found to play a leading role in the reduction of dissolved-oxygen concentration
in lake water in winter. The total decrease in the amount of dissolved oxygen since the beginning of under-ice period until
mid-April was shown to amount to one third of the initial value. The year-to-year variations in winter oxygen consumption
are ~10%, suggesting the process to be stable in the years of observations. The rate of oxygen consumption and variations
in dissolved oxygen content of lake water in winter were evaluated. The analysis and literary data allow us to conclude that
the hydrophysical processes taking place in shallow lakes in winter have a considerable effect on their oxygen regime. 相似文献
10.
Motion of water in an ice-covered shallow lake 总被引:1,自引:0,他引:1
M. P. Petrov A. Yu. Terzhevik R. E. Zdorovennov G. E. Zdorovennova 《Water Resources》2007,34(2):113-122
The results of analysis of data collected by direct measurements of currents in shallow Vendyurskoe Lake in winter are given. The horizontal motions of water in the lake are shown to exist throughout the freeze up period. Dominating frequencies are identified in variations in water motion with periods close to those of the longitudinal and transverse seiches of the lake. Experiments are used to show that oscillatory motions of ice can serve a source of energy for the development of water mass movement in ice-covered lakes. Wind is shown to be the most likely factor generating oscillatory motions of water in ice-covered lakes. It is shown that the velocities of residual currents existing in a lake decrease in winter and their maximum values occur above the deepwater part of the lake within the first and second months of freeze-up. 相似文献
11.
Loreto Rossi M. Letizia Costantini Pasquale Carlino Antonella di Lascio David Rossi 《Aquatic Sciences - Research Across Boundaries》2010,72(2):227-236
The high numbers of primary producers represent multiple sources of organic matter accumulating onto lake bottoms. The difficulty
of distinguishing the relative contribution to the mixture presents considerable challenges to the analysis of these organic
deposits. In this study, dual-stable isotope analysis and IsoSource model were used to identify allochthonous and autochthonous
components of detritus deposits (Particulate Organic Matter: POM) at two different bottom slope sites of a volcanic lake (lake
Bracciano). Experiments were carried out to calibrate IsoSource on constructed plant mixtures and assess changes in isotope
ratios during plant decomposition. IsoSource satisfactorily discriminated the constructed mixture sources with a few exceptions.
Changes in isotopic enrichment during decomposition were low, and thus did not represent a confounding variable in the isotopic
analysis. By contrast, chemical and geological differences of the study sites were associated with differences in plant δ13C and δ15N values (more than 2‰ within single plant species). At both sites, the isotopic signals of POM fell between polygons delineated
by source end members with an evident shift of δ13C toward allochthonous sources. POM amount and diversity were greater at the flatter bottom site, where allochthonous contributions
were larger than at the other site. In particular, IsoSource ranked species contributions as follows: A. glutinosa > P. australis > A. donax > S. alba > P. nigra > the benthic macroalga Chara sp. at the first site, and A. glutinosa > P. nigra > the aquatic macrophyte C. demersum at the latter. The composition of littoral POM was determined by allochthonous sources in proportion to their relative abundances
(as percent land cover) with differences between sites due to bottom slope. 相似文献
12.
本文建立了浅水湖泊水质系统滤波模型和相应算法,根据滇池流场比较稳定等特点,对湖泊进行单元分区,考虑模型误差扰动和观测误差扰动的存在,建立系统的状态方程和观测方程,然后采用吉尔(Gill)算法求解微分方程,进行系统多点连续模拟和实时预报,用此法对1988年滇池BOD,COD时空变化进行连续预报,取得满意结果。 相似文献
13.
Karl E. Havens 《Aquatic Sciences - Research Across Boundaries》1999,61(2):150-167
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Paleolimnological evidence of limnetic nutrient concentration equilibrium in a shallow, macrophyte-dominated lake 总被引:5,自引:0,他引:5
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热带浅水湖泊后生浮游动物群落结构对生态修复的响应 总被引:5,自引:4,他引:1
热带浅水湖泊后生浮游动物群落以轮虫和小型枝角类为主,往往缺乏大型浮游动物,其影响因子还存在争议,因此通过减少鱼类,提高大型后生浮游动物密度,从而增强对浮游植物的下行控制、修复热带富营养化湖泊的方法受到质疑.暨大南湖位于广州暨南大学校园内,是热带富营养化浅水湖泊,于2014年1—2月实施以鱼类去除和水生植被重建为主的生态系统修复工程,以期改善水质.通过对南湖修复前后水质、后生浮游动物以及修复后鱼类群落的调查分析,研究了后生浮游动物群落对修复的响应.结果表明:与修复前相比,总氮、总磷和叶绿素a浓度显著降低,透明度显著上升.枝角类丰度和生物量显著增加,修复后初期出现较高密度的大型枝角类蚤状溞(Daphnia pulex),桡足类丰度和生物量没有显著变化,轮虫丰度下降而生物量上升;后生浮游动物体长和生物多样性显著增加.随着鱼类密度的增加,蚤状溞丰度快速降低,后期鱼类减少后蚤状溞丰度又有所升高.因此,本研究显示鱼类是控制热带浅水湖泊大型浮游动物种群的主要因素,由于控制鱼类密度以维持较高大型浮游动物密度较为困难,因此单纯生物操纵在热带浅水湖泊修复中难以取得显著效果. 相似文献
19.
Jorge Feliciano Ontiveros-Cuadras Ana Carolina Ruiz-Fernández Joan-Albert Sanchez-Cabeza Libia Hascibe Pérez-Bernal Michel Preda Federico Páez-Osuna 《国际泥沙研究》2018,33(2):183-190
Two lead-210 (210Pb) dated sediment cores from Chapala Lake were studied to identify the mineral composition of the sediments and to discuss its relation with trace metals. Minerals and trace metals reflected the domain of volcanic rocks (i.e. basalts, rhyolite and andesite) that characterize Chapala Lake and the Lerma River watershed. Redundancy analyses (RDA) were used to identify the sedimentary variables (magnetic susceptibility, organic matter, sand content, and mineral composition) that could be related to elemental composition. Despite the distance between the two cores (7.3 km) and hydrodynamic circulation the RDA showed that the main mechanism that controls the input of mineral species, and, therefore, element distributions in the lacustrine sediment of Chapala Lake, is related to the weathering of volcanic rocks in the Lerma-Chapala watershed, the consequent runoff and transport of fine grained catchment materials, and later in-lake processes. These findings highlight the importance of controlling watershed erosion to contribute to the improvement of the environmental quality of the lake. 相似文献