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1.
The phosphorus fractions, the alkaline phosphatase activity (APA) and other water chemical parameters were concomitantly monitored from April 2003 to October 2004 in different eco-type sites of Lake Taihu. During the stages of algae growth, the phosphorus fractions and their relationships with APA in different ecotype sites were discussed and the phosphorus mineralization rate was calculated. In the water of Lake Taihu, most of the phosphorus (70.2%) could be attributed to the suspended particulate phosphorus, while the dissolved reactive phosphorus (DRP) seems to contribute less than 7%. About 58% of the total phosphorus, however, can be hydrolyzed as inorganic phosphate to compensate for phosphorus deficiency of algae and bacteria growth. During the different algae growth stages, the APA and its Kinetic parameters were varied significantly between different ecotype sites of Lake Taihu. This trend is also visible by comparing the phosphorus mineralization rate, and the most rapidly phosphorus turnover time is only several minutes. The fast recycle of phosphorus can, to some extent, be explained that the phosphorus source of algal blooms. The phytoplankton seems to compensate for phosphorus deficiency by using the alkaline phosphatase to hydrolyze phosphomonoesters.  相似文献   

2.
Spatiotemporal variations of P species and adsorption behavior in water column, interstitial water, and sediments were investigated in the large shallow eutrophic Lake Chaohu. Ortho-phosphate (Ortho-P) and total phosphorus (TP) concentrations were significantly higher in the western part than in the eastern part of the lake, due to different nutrient inputs from the surrounding rivers. Moreover, paniculate phosphorus (PP) concentration was in a similar spatial pattern to Ortho-P and TP concentrations, and also showed significantly positive correlation with the biomass of Microcystis, indicating more uptake and store of phosphorus by Microcystis than by other algae. Increase of pH and intensive utilization of P by phytoplankton were the main factors promoting P (especially Fe-P) release from the sediment to interstitial water during the cyanobacterial blooms in Lake Chaohu. Spatial dynamics in TP concentration, P species and adsorption behavior of the sediment, coupled with the statistical analyses, suggested that the spatial heterogeneity of P contents in the sediment was influenced by various factors, e.g. human activities, soil geochemistry and mineral composition. In spite of similar TP contents in the sediments, increase in proportion of Fe-P concentration in the sediment may result in a high risk of P release.  相似文献   

3.
1 Introduction in China, with an area of 4400 km2 and a drainage area With the advancement of global change study, peo- of nearly 29,660 km2[2]. Occurring at a “climatic triple ple are paying more and more attention to the conti- junction” among the East Asian monsoon, Indian nental environment (in which we reside), its evolution Monsoon and the Westerly Jet Stream, it lies in the and its future tendency. As a component of the global transitional belt of the east monsoonal humid areas sys…  相似文献   

4.
The state of the water area in the Bays of Koz’mina and Lake Vtoroe (Nakhodka Gulf is evaluated. The data given include water temperature and salinity, biochemical oxygen demand, pH, alkalinity, chlorophyll a, organic matter, biogenic elements, oil products, detergents, polycyclic aromatic hydrocarbons, phenols, and organochlorine pesticides in water and bottom sediments. Pollutants may enter the system of bights from both onshore sources and the open part of the bay. The water and bottom sediments in this part of the bay show higher values of BOD5 and the concentrations of oil products, polycyclic aromatic hydrocarbons, phenols, and organochlorine pesticides. The anthropogenic load on the water body is shown to increase because of the new industrial construction on its shore.  相似文献   

5.
The Yellow River(YR) capture of the Huai River had a profound effect on the landscape evolution,ecology, and social development in China, disrupting the evolution of some vital shallow floodplain lakes.Because of the absence of lacustrine sediment provenance analysis, previous studies were inadequate in distinguishing the influence of YR capture on paleoenvironmental changes in these lakes, especially on landscape evolution, redox conditions, lake level changes, and organic productivity. The cur...  相似文献   

6.
Unlike other lakes in the McMurdo Dry Valleys, Antarctica, Lake Vida has a thick (~ 19 m) ice cover sealing a liquid brine body of unusually high salinity (~ 245 g/L) from the atmosphere. To constrain the conditions under which the atypical Lake Vida ice cover formed and evolved, 19 ice samples were collected down to a depth of ~ 14 m, together with three brine samples trapped in the ice at ~ 16 m for analysis of helium, neon, argon, krypton, and xenon concentrations. The broad pattern of noble gas concentrations for Lake Vida samples is fundamentally different from that of air saturated water (ASW) at 0 °C and an elevation of 340 m for salinities of 0 (ice) and 245 g/L (brine). Overall, ice samples are enriched in He and depleted in Ne with saturation relative to ASW averages of 1.38 and 0.82, respectively, and strongly depleted in Ar, Kr, and Xe with relative saturations of 0.10, 0.06, and 0.05, respectively. By contrast, brine samples are generally depleted in He and Ne (relative saturation averages of 0.33 and 0.27, respectively) but enriched in Ar, Kr, and Xe, with relative saturation averages of 1.45, 3.15, and 8.86, respectively. A three-phase freezing partitioning model generating brine, ice and bubble concentrations for all stable noble gases was tested and compared with our data. Measured brine values are best reproduced for a salinity value of 175 g/L, a pressure of 1.1 atm, and a bubble volume of 20 cm3 kg?1. Sensitivity tests for ice + bubble samples show an ideal fit for bubble volumes of ~ 1–2 cm3 kg?1. Our results show that the conditions under which ice and brine formed and evolved at Lake Vida are significantly different from other ice-covered lakes in the area. Our brine data suggest that Lake Vida may be transitioning from a wet to a dry-based lake, while the ice + bubble data suggest at least partial re-equilibration of residual liquid with the atmosphere as ice forms at the top of Lake Vida ice cover.  相似文献   

7.
Based on the total phosphorous (TP) concentration in sediment core, the TP concentration in lake water quantitatively reconstructed from fossil diatoms and diatom-TP transfer function in the Longgan Lake during the last 200 years, the temperature and precipitation data from meteorological observation for the last 50 years, the temperatures and precipitation sequences of climate simulation for the last 200 years, as well as the amount of the agricultural phosphate fertilizer in Longgan area for nearly 50 years, the characteristic and the law of the nutrient status evolution were analyzed, and the influence of the climatic factor, the anthropologic factor and the aquatic biology factor on the nutrient status evolution and its mechanism were discussed for the Longgan Lake during the last 200 years. The results showed that, in the nearly 200 years, the TP concentration in the sediment core of the Longgan Lake gradually increased, its range of variation was situated between 330-580 mg/kg, the mean value was 388 mg/kg, a nearly 30-year vibration adjustment period existed at 1950 around. The TP concentration in lake water changed in a different way. Before 1950, it had a slow increasing tendency in fluctuated background, to 1950 around it reached up to the mean value (52.18μg/L), and vibrated and adjusted around the mean value, then it fast declined, its change range was situated between 37.75-62.33μg/L. The analyses indicated that, in the centennial time scale, the climate change was the main controlling factor, while in the decadal time scale in the recent 50 years, human activities were the leading factors for the nutrient status evolution of the Longgan Lake. 60% of the variability of the TP concentration in the sediments and 57% of that in lake water were due to human activities. The differentiation between phosphorus concentration in the sediment and in the lake water reflected the response processes and the adjustment abilities of the lake aquatic ecosystems to the lake nutrient level, implying the maintenance and the destruction of the balances between the algae and the aquatic plants, as well as the corresponding accumulating characteristics of the phosphorus.  相似文献   

8.
The distribution of benthic invertebrates and their subfossil remains was examined within the basin of De Waay, a dimictic, eutrophic lake in the Netherlands. We focused on Chironomidae, but also report the abundances of 11 invertebrate groups that potentially produce chitinous remains that are preserved in the fossil record, although their remains could only be identified at a coarser taxonomic resolution. Most living invertebrates sampled in different seasons were constrained to the littoral zone, with the exception of a few taxa (Ceratopogonidae, Chaoborus flavicans, and Chironomus) that are adapted to low oxygen conditions in the seasonally anoxic profundal zone. In contrast, assemblages of invertebrate remains in lake surface sediments were similar in the entire lake basin, suggesting that considerable numbers of invertebrate remains are transported and redeposited off-shore in Lake De Waay, due to its steep bathymetry. These results indicate that a single sediment sample obtained from the centre of this lake contains subfossil invertebrate remains originating from the entire lake basin. In Lake De Waay, the majority of taxa found in the living assemblages were identified as remains in lake surface sediments, at least for the Chironomidae that could be identified at a similar taxonomic level in living and subfossil assemblages. Of the total 44 chironomid taxa found in Lake De Waay, 35 taxa occurred in the living assemblages and 34 taxa occurred in the subfossil assemblages. Thirty chironomid taxa occurred both as living and subfossil specimens, and on average these 30 taxa represent 94% of the specimens encountered in a sediment sample. Five rare chironomid taxa present as living larvae were not detected in the subfossil assemblages. Conversely, eight rare and four common chironomid taxa were found in subfossil remains, but not in living assemblages. Our results indicate that subfossil assemblages in surface sediment samples provide spatially integrated and representative samples of the living assemblage. However, a combined approach examining both the living benthic invertebrate fauna and invertebrate remains in lake surface sediments will potentially give a more complete and detailed overview of benthic invertebrates in a lake ecosystem than an approach based exclusively on one of these groups.  相似文献   

9.
Based on three continuous in situ underwater light field measurement under different wind waves conditions in Longgan Lake, Meiliang Bay of Taihu Lake in July 2003 and littoral zone near TLLER in July 2004, respectively, the effects of sediment resuspension caused by wind waves on PAR diffuse attenuation, absorption coefficients and euphotic depths are analyzed. In Longgan Lake, PAR diffuse attenuation coefficients during small, middle and large wind waves were 1.74, 2.02 and 2.45 m-1, respectively, and the corresponding PAR spectral diffuse attenuations ranged from 0.98 to 2.97, 1.34 to 3.95 and 1.80 to 5.40 m-1, respectively. In Meiliang Bay, PAR diffuse attenuation coefficients were 2.63, 3.72, 4.37 m-1 during small, middle and large wind waves. PAR diffuse attenuation coefficients increased by 41% and 66% from small to middle, large wind waves, respectively. Absorption coefficients integrated over the range of PAR of CDOM, phytoplankton were 0.26, 0.28 m-1; 0.76, 0.49 m-1, respectively during middle and large wind waves. Absorption coefficients integrated over the range of PAR of non-algal particulate matter and total suspended particulate matter increased from 0.94 to 1.73 m-1, and from 1.70 to 2.22 m-1, respectively during middle and large wind waves. Relative contributions of absorption coefficients of non-algal particulate matter to total absorption coefficient integrated over the range of PAR were 44.14%, 65.05%, respectively, during middle and large wind waves. PAR euphotic depths decreased by 0.40, 0.19, 0.20 m from middle to large wind waves in Longganhu Lake, Meliang Bay and littoral zone near TLLER. Significant correlations were found between transparency, PAR diffuse attenuation coefficients, euphotic depths and total suspended paniculate matter, wind velocity, wave height. Most significant correlations were found between transparency, PAR diffuse attenuation coefficients, euphotic depths and inorganic suspended paniculate matter but low correlations for chlorophyll a, dissolved organic carbon. Increase of total suspended paniculate matter, especially inorganic suspended paniculate matter caused by wind waves was the dominant factor affecting underwater light field in shallow lakes in the middle and lower reaches of the Yangtze River based on observations at three stations.  相似文献   

10.
Lake contamination by anthropogenic activities has become a serious threat to the aquatic ecosystem due to the presence of a high concentration of toxic heavy metals.In this study,a contaminated Lake Hussain Sagar in India was assessed for toxic heavy metal pollutants at sites associated with industrial discharges and idol immersion activities.The observed high concentration of As,Cd,Pb,Zn,Cu,and Ni in the surface water was due to industrial effluent discharge.About 1.5 times the high concentration of the same elements were observed in surface sediments(0-10 cm)by both industrial discharges and idol immersion activities,compared to deep sediments(0-40 cm)associated only with industrial discharge.The depth-wise variation of heavy metal concentration in surface sediments is due to sorption and settling behavior of suspended solids;whereas in deep sediment,it is due to constant loading of effluents,over a period of time.The sorption capacity of surface sediments is in increasing order as Pb>Cd≥Ni>Cr>Zn>Cu,and the desorption revealed that Pb and Cu were retained to a greater extent due to high clay and organic content.By fractionation study,20-50%of Zn and 50-80%of Cd were associated with exchangeable and carbonate fraction of sediments.By risk assessment code,Zn and Cd are classified under high risk to a very high-risk category,and Cr,Pb,Ni,and Cu are classified under the medium risk category.The enrichment factor value of sediments for Cd(20.42-119.48),Zn(2.19-4.85),Cu(2.02-3.19),and Pb(2.85-7.72)signifies the significant pollution by anthropogenic activities.Therefore,this study evaluates the intensity and distribution of heavy metals in the lake environment for remediation and restoration of the lake ecosystem.  相似文献   

11.
The sedimentary environment change, trophic evolution and heavy metals pollution history of the northern Taihu Lake in the last 100 years are studied according to the sedimentary geo-chemical proxies of the core sediments, such as grain size, nutrients, heavy metals, diatom, etc. The nutrients in the sediments depended mainly on the lake internal circulation and the heavy metals were from natural geogenic sources before the 1920s, which were not influenced by human activities generally, and grain size was one of the key factors influencing heavy metals content in the sediments. The alternation of manner and strength of human activities in Taihu Lake catchment before and after the 1920s made the lake sediments coarser, and hence heavy metals and TP content decreased contrasted with that before the 1920s. TP content in sediments and water increased from the 1950s to late 1970s due to anthropogenic pollutants discharge, and the lake belonging to mesotrophic state. TN and TOC content and C/N ratio increased due to the increasing external pollutants into Taihu Lake by human activities, TP content also increased obviously in water and sediments, and the diatom association was dominated by eutrophic species since the late 1970s, indicating the eutrophication state of Taihu Lake in this period. Meanwhile the increasing in heavy metals content, such as Cu, Mn, Ni, Pb and Zn, and their proportion of valid fractions in the sediments indicates that they all result from human pollutants since the late 1970s. The heavy metals in the surface sediments have certain potential biological toxicity due to the higher SEM/AVS ratio.  相似文献   

12.
This work presents a scenario to demonstrate how a given lake (Lake Stora Kröntjärn, Sweden) would respond to changes in colour related to lumbering operations in its watershed. The questions posed are: How would lake colour values increase, for how long would such increases last and how would this influence the production and biomasses of key functional organisms in the lake? The work is based on a comprehensive lake ecosystem model, LakeWeb, which accounts for production, biomasses, predation, abiotic/biotic interactions of nine key functional groups of organisms, phytoplankton, bacterioplankton, two types of zooplankton (herbivorous and predatory), two types of fish (prey and predatory), as well as zoobenthos, macrophytes and benthic algae. The LakeWeb-model has been calibrated and critically tested using empirical data and regressions for many lakes and it can capture typical functional and structural patterns in lakes. To obtain results like these by traditional field-work in one or more lakes would be very demanding (in terms of money, persons and time). It has been shown that single tributary peaks in colour concentrations are often "drowned" in weekly mean lake values. The lumbering operations must be extensive and continue for a long time to cause significant increases in tributary colour values in order to significantly influence fundamental lake foodweb structures. This means that it is often realistic to assume that lumbering activities do not strongly influence lake foodweb structures. The LakeWeb-model with the given mass-balance model for lake colour can be a useful tool to assess situations when this might not be valid.  相似文献   

13.
Number 1Features,Impacts and Causes of the High Temperature and Large Precipitation Event in the Tibetan Plateau and Its Adjacent Area During 40———30kaBP··············-····-·-···-··-·SHI Ya.feng,JIA Yulian,YUGe,yANG Dayuan,FAN Yunqi,LJ Shijie,暇NG Yun乃j(11)Construction of Flood Control Engineering and Countermeasures for Flood Disaster Mitiga— tion in Taihu Basin………………………………………………………………LJN Zexin(18)Dynamic Water——Lev…  相似文献   

14.
ABSTRACT

The aim of the study was to locate and describe groundwater outflows in a selected lake basin and measure the spring output of water and the physical characteristics of the studied waters (temperature and conductivity). The final aim was to gauge the effects of the spring output on the lake hydrology. The time scope of the work included the period from January 2011 to September 2012. The spatial scope of the work included the area of Lake Raduńskie Górne and its direct catchment located in the Kashubian Lake District in northern Poland. Four groundwater outflows were located in the course of the study. Their total output was 4.6 L s?1 and ranged between 0.5 and 2.5 L s?1. This produces an annual yield of about 145 000 m3 year?1. These results confirm that one of the forms of supply to the lakes are the under-lake springs. For lakes located in the area of young glacial accumulation this can be decisive.
Editor D. Koutsoyiannis Associate editor D. Gerten  相似文献   

15.
This paper focuses on examining the validity and reliability of the contingent valuation method (CVM) in the case of evaluation of ecotourism resources in Dalai Lake Protected Area (DLPA). The CVM is a primary method to evaluate resource value, however, it is subject to criticism because of its bias. Many factors result in CVM evaluation bias, which decreases validity of the method. An important factor is that the CVM assumes that all of the respondents are certain about their answers. In fact, many respondents are not very certain about their answer, therefore, identifying the respondents’ certainty level and exploring a proper method to address it are critical issues. There are three objectives in the present study: first, to identify the uncertainty treatment that can more significantly reduce the hypothetical bias, resulting in a greater closeness to the Willingness to Pay (WTP) in a real setting; second, to identify the determinants of the respondents’ uncertainty; and third, to test the reliability of the respondents’ payment in a real setting and a hypothetical setting by comparison with our study in 2010. One thousand three hundred fifty questionnaires about the DLPA were distributed in face-to-face interviews targeted at Hulunbeier inhabitants, and 1142 questionnaires were collected. The primary main conclusions are summarized as follows. First, the treatment of a real setting reduced the hypothetical bias, increased the WTP accuracy and had better reliability compared with the hypothetical setting. Second, income, impact (the impact of resource development on DLPA) and environmental attitudes had a significant positive influence on the respondents’ certainty in hypothetical and real settings, and income and impact of resource development on DLPA had more significant influences in the real setting than in the hypothetical setting. Third, the computation of the mean WTP showed that the exposure model and the asymmetric uncertainty model YES6 fell within the 95% interval around the point estimated from the real model. The WTP of the SUM (symmetric uncertainty model) was much higher than that of the real model and the hypothetical model.  相似文献   

16.
The goal of the present work is to perform a geochemical assessment of High Dam Lake bottom sediments for determining the fate, dispersion and levels of trace elements causing environmental pollution, and provided an access to their probable sources. The sediment samples were analyzed using ICP-MS for 20 elements; Ag, Ba, Cr, Cu, Ga, Hf, Mn, Pb, Rb, Sc, Se, Sn, Sr, Ta Th Ti, T1, U, V and Zr, and their obtained data were treated using statistical, graphical and mapping techniques. The results showed the data set of all analyzed elements affected by outliers and extreme values that caused deviation away from normality. Kruskal-Wallis test revealed that median of some trace element levels in Lake sediments, was not significantly different and other elements rejected the Null hypothesis. Most analyzed elements had high values of median and mean in sediments of Lake Nubia rather than Lake Nasser and their normalization gave the same results of calculated environment factors. Subsequently, Lake Nubia sediments possessed high combined EF levels ofTh, Sc, Sn, Ag, Zr, Hf, Ta, Sr, U, Ti, V, Cr, and Mn, causing significant contamination, which was great potentially related to industrial, agricultural, urbanization and mining activities. Whereas, combined EF of Se, Cu, Ga, Pb, Ba, Rb, and Tl, which are highly elevated in southern Lake Nasser sediments owing to their source are great possibly derived from Lake Nubia and geogenic activities. With decreasing distance towards the High Dam body, the contaminant elements were diminished due to reduction in the environmental factors and Sudanese pollution sources leading to the northern Lake Nasser considered to be less contaminated. Overall, the present study is an environmental alert for contaminated sediments that carried contaminants and considered the secondary source of pollution impact on ecosystem, and subsequently, their environmental risk on Human health.  相似文献   

17.
The unique ecological landscapes are composed of the mountain systems with the obviousvertical differentiation, vast natural desert systems, and oasis systems on which the human beings rely for the existence in the arid areas in West China. Oases are the …  相似文献   

18.
During the 2018 eruption of Kīlauea Volcano, Hawai'i, scientists relied heavily on a conceptual model of explosive eruptions triggered when lava-lake levels drop below the water table. Numerical modeling of multiphase groundwater flow and heat transport revealed that, contrary to expectations, liquid water inflow to the drained magma conduit would likely be delayed by months to years, owing to the inability of liquid water to transit a zone of very hot rock. The summit of Kīlauea subsequently experienced an ∼2-month period of consistent repeated collapses, and the crater now extends below the equilibrium position of the water table. Liquid water first emerged into the deepened crater in late July 2019. The timing of first appearance of liquid water (about 14 months postcollapse) and the rate of crater lake filling (currently ∼27 kg/s) were well-predicted by the numerical modeling done in late spring 2018, which forecast liquid inflow after 3 to 24 months at rates of 10 to 100 kg/s. A second-generation groundwater model, reflecting the current crater geometry, forecasts lake filling over the next several years. The successful 2018 to present forecasts with both models are based on unadjusted in situ permeability estimates (1 to 6 × 10−14 m2) and water-table elevations (600 to 800 m) from a nearby research drillhole and geophysical surveys. Important unknowns that affect the reliability of longer-term forecasts include the equilibrium water-table geometry, the rate of evaporation from the hot and growing crater lake (currently ∼29,000 m2 at 70-80 °C), and heterogenous permeability changes caused by the 2018 collapse.  相似文献   

19.
We analyze the variations in the horizontal and vertical components of the Earth??s electromagnetic field measured at nine points onshore along the southern part of Lake Baikal. It is found that variations with a period of a few tens of seconds have decayed 20 minutes before the earthquake. This is a regional effect. It is observed in the variations of the horizontal magnetic field. The intensity of the effect in the electric field is site-specific, which is due to the nonuniform distribution of electric conductivity in a medium, as revealed by the deep magnetotelluric sounding. The electric field also experiences a coseismic variation associated with the seismic wave. This effect is stronger pronounced in the vertical electric field. The bay-like anomalies that precede and accompany the Kultuk earthquake are revealed in the electric field of intraterrestrial origin and in the behavior of the electric tipper. These anomalies are concurrent with the rise of the ground water level in the borehole. The probable nature of the revealed anomalies is discussed.  相似文献   

20.
: Phytoplankton primary production measurements and sediment trapping in the large (270 km2) shallow (mean depth 2.8 m) Lake Võrtsjärv were performed during ice-free periods in 1995-1996. Sedimentation rate varied from 26 to 700 g DWm-2d-1 (DW=dry weight), with a mean value of 170 g DWm-2d-1. Under the influence of prevailing westerly and south-westerly winds, the sedimentation rate was higher in the northern part, and lower in the western and southern parts of the lake. An increasing trend towards autumn could be followed in both years. The mean sedimentation rates in the dry year 1996 with a low lake water level exceeded those of the “normal” 1995 by a factor of more than two. New sedimentation formed 10-15 % of the downward sediment flux in 1995 and 4-6 % in 1996, while the major part of entrapped matter originated from resuspended bottom sediments. The dynamics of gross sedimentation showed no relation to the primary production but correlated significantly with the concentration of suspended solids, with the average wind speed and with the mean depth of the lake during trap exposition.¶The composition of entrapped matter did not show seasonal variation but differed between the sampling stations. The amount of particulate organic matter (POM) per DW varied from 11 % at places where the bottom sediment consisted of moraine or sand to 28 % at places with muddy bottom. N:POM was rather stable (45-61 mgg-1, Cvar = 6 %). The variability of P:POM (3.5-7.1, Cvar = 20 %) exceeded that of P:DW (0.75-1.31 mgg-1, Cvar = 10 %) showing the essential role of mineral-bound P in the settling material. In these conditions, the N:P ratio was determined by the POM content of settling matter. POM:DW in settling material was generally higher than in the 0-2 cm layer of bottom sediments.  相似文献   

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