West Taihu Research Articles

Distribution, Sources, and Ecological Risk Evaluation of Heavy Metals in Surface Sediments of Taihu Lake

For the surface sediment samples of Taihu Lake in 2010, the eight physicochemical indices of pH, temperature, Eh, water content, porosity, grain size, total phosphorus, and Loss-on-ignition were measured and analyzed, along with the contents of nine heavy metals:Cu, Zn, Ni, Cr, Pb, Ba, Mn, Co, and V. The order of magnitudes of heavy metal content of surface sediments in Taihu Lake was:Mn>Ba>Zn>Cr>V>Ni>Pb>Cu>Co. This suggested that the contents of the nine heavy metals were beyond the background value, which had a close connection to the geology of the Taihu Lake Basin and were influenced by human activity to varying degrees. The clustering analysis and the spatial distribution of the heavy metals revealed that the concentrations of heavy metals in the North and South Taihu Lake sections decreased from the lake shore to the lake center, the concentrations of heavy metals in the West Taihu Lake section increased from the lake shore to the lake center, and the distribution of heavy metals in the center of the lake remained relatively uniform. According to the correlation study, the metal elements were positively correlated with one another to varying degrees, indicating that they originate from the same source of pollution. According to the PCA and PMF analyses, there were some different sources of heavy metals in Taihu Lake, in which the transportation and industrial complex source were the most important sources, the diagenesis was the second major source, and agriculture was the third major source. Furthermore, the heavy metal pollution was evaluated using the geoaccumulation and the potential ecological risk indices. This offers a solid theoretical backing for the future management of heavy metal pollution in Taihu Lake.

Comparison between Machine-Learning-Based Turbidity Models Developed for Different Lake Zones in a Large Shallow Lake

Machine learning has been used to mine the massive data collected by automatic environmental monitoring systems and predict the changes in the environmental factors in lakes. However, further study is needed to assess the feasibility of the development of a universal machine-learning-based turbidity model for a large shallow lake with considerable spatial heterogeneity in environmental factors. In this study, we collected and examined sediment and water quality data from Lake Taihu, China. Three monitoring stations were established in three lake zones to obtain continuous time series data of the water quality and meteorological variables. We used these data to develop three turbidity models based on long short-term memory (LSTM). The three zones differed in terms of environmental factors related to turbidity: in West Taihu, the Lake Center, and the mouth of Gonghu Bay, the critical shear stress of bed sediments was 0.029, 0.055, and 0.032 N m−2, and the chlorophyll-a concentration was 23.27, 14.62, 30.80 μg L−1, respectively. The LSTM-based turbidity model developed for any zone could predict the turbidity in the other two zones. For the model developed for West Taihu, its performance to predict the turbidity in the local zone (i.e., West Taihu) was inferior to that for the other zones; the reverse applied to the models developed for the Lake Center and Gonghu Bay. This can be attributed to the complex hydrodynamics in West Taihu, which weakens the learning of LSTM from the time series data. This study explores the feasibility of the development of a universal LSTM-based turbidity model for Lake Taihu and promotes the application of machine learning algorithms to large shallow lakes.

Source-oriented ecological risk assessment of heavy metals in sediments of West Taihu Lake, China

The geographical location of West Taihu Lake determines that it is the entrance of the whole Taihu Lake, and the intensive industries around it pose a great threat to the ecology of Taihu Lake. We innovatively combined Pb isotope ratio analysis with ecological risk assessment index to quantify the source-oriented ecological risk of heavy metals (HMs) in the sediments of West Taihu Lake. In this study, the representative HMs Zn, Pb, Cr, and Cd in the surface (0-2cm) sediments of West Tai Lake were determined, and the ecological risk assessment of HM sources was carried out based on the Pb isotope ratio and ecological risk index. The results showed that HMs were significantly enriched in the south and thewest of the study area. The average geo-accumulation index (Igeo) of Pb was unpolluted, Cr and Zn were between unpolluted and moderately polluted, and Cd was moderately polluted. The average ecological risk index (Ei) of Pb, Cr, and Zn was low, and only Cd reached a considerable risk (ECd = 120.7), which accounted for 89.8% of the comprehensive ecological risk index (RI). However, the RI in the whole study area (RI = 134.4) still indicated low risk. There was a significant correlation between Pb and other HMs (P < 0.05). The IsoSource analysis showed that the order of contribution rate was fossil fuels (48.0%) > industrial sources (35.8%) > natural sources (14.9%) > agricultural sources (1.3%). The HM pollution caused by fossil fuel combustion and industrial activities reaches a moderate ecological risk, whereas natural sources and agricultural sources pose a low risk. Overall, the main sources of HM pollution are anthropogenic, which pose moderate ecological risk to the study area and should be paid more attention to.

Linking microbiomes with per- and poly-fluoroalkyl substances (PFASs) in soil ecosystems: Microbial community assembly, stability, and trophic phylosymbiosis

Microbiomes are vital in promoting nutrient cycling and plant growth in soil ecosystems. However, microbiomes face adverse effects from multiple persistent pollutants, including per- and poly-fluoroalkyl substances (PFASs). PFASs threaten the fertility and health of soil ecosystems, yet the response of microbial community stability and trophic transfer efficiencies to PFASs is still poorly understood. This study explored the spatial patterns of PFASs in topsoil environments from the West Taihu Lake Basin of China and links their presence to soil microbial community stability at compositional and functional levels. Our results revealed that PFBA (13.87%), PFTrDA (11.63%), PFDoA (11.02%), PFOA (10.99%), and PFOS (10.39%) contributed the most to the spatial occurrence of PFASs. Soil properties, including salinity (14.47%), uniformity (9.68%), dissolved inorganic carbon (8.62%), and clay content (8.18%), affected PFASs distribution the most. In soil microbiomes, eukaryotic taxa had wider niche breadths and stronger community stability than prokaryotes when exposed to PFASs (p < 0.05). The presence of PFBA and PFHpA inhibited the functional stability of archaeal and bacterial communities (p < 0.05). PFBA and PFPeA reduced the structural stability of heterotrophic bacteria and Myxobacteria, respectively (p < 0.05). Based on null modeling, PFPeA significantly regulated the assembly processes of most microbial sub-communities (p < 0.01). The trophic transferring efficiencies of autotrophic bacteria to metazoan organisms were directly stimulated by PFASs (p < 0.05), and the potential trophic transferring efficiencies of methanogenic archaea to protozoa were inhibited by PFASs (p < 0.05). This study highlighted the potential contributions of PFASs to soil microbial community stability and food webs during ecological soil management.

Source identification of particulate organic carbon using stable isotopes and n-alkanes: modeling and application

Particulate organic carbon (POC) sources, which regulate dissolved organic carbon, sediment organic carbon, and inorganic carbon via deposition, degradation, and mineralization, play an important role in lake ecosystems. Linear or Bayesian algorithms on isotope and n-alkanes have been widely used to identify the source proportion of organic carbon. However, the applicability of these methods is ambiguous because of the unilateral advantages of each model and trace factors. To test the applicability of the various methods for identifying POC sources, we analyzed dual isotopes and n-alkanes in surface water samples of Lake Taihu, and Multi-source mixing model and Bayesian mixing model were used to distinguish between endogenous and exogenous contributions. Carbon isotope presented a clear advantage in West Taihu (-21.85 ± 0.78‰) and Southwest Taih (-22.61 ± 1.35‰); nitrogen isotope also showed high values in Meiliang Bay (9.76 ± 0.92‰). The majority of the lake was dominated by short-chain n-alkanes, except for East Taihu Lake (dominated by medium-chain n-alkanes) and areas with riverine input (dominated by long-chain n-alkanes). Different principles between the Bayesian mixing model (based on the Markov Chain Monte Carlo algorithm) and the Multi-source mixing model (based on linear estimation) caused discrepancies in the estimations of source contributions. But the fraction of chemical compounds during the migration process, and the overlap of potential sources play important role in the inconsistency of results. The estimations from the different models were consistent in indicating the dominance of endogenous organic carbon in Lake Taihu (mean of 60.18 ± 20.26%), particularly in the north and western regions (West Taihu, Meiliang Bay, and Southwest Taihu). This was likely due to algal aggregation influenced by human activities and climatic factors.

Application of APCA-MLR receptor model for source apportionment of char and soot in sediments

Black carbon (char and soot) has attracted increasing attention due to its important role in the global carbon cycle, adsorption of pollutants (polycyclic aromatic hydrocarbons (PAHs) and heavy metals), climate effects and threats to human health. However, few studies have included source analysis of black carbon (char and soot). In this study, the levels of char, soot and PAHs in sediments of West Taihu Lake were assessed, and an absolute principal component analysis followed by multiple linear regression (APCA-MLR) receptor model was used to successfully analyze the material sources of char and soot, providing a new perspective and method for exploring the sources of char and soot. The contributions of coal combustion sources to char and soot are 62.0% and 43.2%, respectively, which are significantly higher than those of biomass combustion sources (13.7% and 19.8%). The contributions of oil combustion sources to char and soot are 24.3% and 37.0%, respectively. The contributions of coal, oil and biomass combustion to char and soot have similar spatial distributions: the coal combustion sources and biomass combustion sources are mainly affected by urban development, which is largely distributed in the northwest of the study area, whereas the oil combustion sources are mainly affected by automobile traffic and lake ports, which are mainly distributed in the west of the study area, and these effects decrease with an increase in offshore distance.

Determination of influencing factors on historical concentration variations of PAHs in West Taihu Lake, China

The adsorption of polycyclic aromatic hydrocarbons (PAHs) by components such as elemental carbon (EC), total organic carbon (TOC), and particles is different, and EC and PAHs are good materials for reconstructing historical human activity patterns and pollution conditions. In this study, the effects of EC (soot and char), TOC and particles of different grain size on PAHs in surface sediments were quantitatively analysed, and their historical concentrations in a sediment core from western Taihu Lake were reconstructed. The contents of soot, TOC, clay, EC and char explained 57.2%, 27.6%, 26.0%, 24.0% and 16.4%, respectively, of the PAH concentrations in surface sediments. The correlation between the soot and PAH levels was significantly higher than that between the char, TOC, and clay contents and PAH levels, and PAHs were mainly affected by the local economic development and human activity, as indicated by metrics of population, highway mileage, coal burning, and industrial output. With the development of the economy of the Taihu Lake Basin, the composition of PAHs in the sediments has changed: the proportion of low-molecular-weight PAHs decreased from 42.4% to 17.5%, and that of high-molecular-weight PAHs increased from 58.7% to 82.5%. The concentration of PAHs in pore water from Taihu Lake over the past 100 years was reconstructed and ranged from 43.1 to 961.2 μg L−1, with an average of 180.7 μg L−1. After China's reform and opening up, the concentrations of various PAHs in Taihu Lake changed from safe to chronic pollution levels. The ratios of lead (Pb) isotopes and the diagnostic ratios of PAHs showed that the main sources of PAHs in western Taihu Lake sediments were human activities such as coal and petroleum combustion.

Estimating Wind-Induced Responses of the Sightseeing Tower of the West Taihu Lake, Changzhou

The wind tunnel test was carried out for the Sightseeing Tower of the West Taihu Lake, Changzhou in this study, and the equivalent static wind loads of the Moon Tower were obtained at different wind angles. Frequency-domain analysis was performed to reveal the wind-induced response dynamics. The distribution diagram of unfavorable equivalent static wind loads was worked out to provide reference for the design of the main structure.

宜兴市莲花荡水系水环境质量现状及其水质评价

莲花荡水系下接乌溪港，是西太湖主要入湖河流之一，水环境功能区划要求其水质达到地表水Ⅲ类。2014年4月(平水期)和7月(丰水期)，对莲花荡水系进行了两次现场调研和采样监测，结果表明：水体中超过Ⅲ类地表水的污染指标主要有高锰酸盐指数、总磷、总氮、氨氮和叶绿素a等，其中氮、磷污染超标严重；受丰水期河水量增加影响，7月份河水水质略优于4月；调研发现，水体主要的污染源为集中畜禽养殖废水、沿岸农村散排生活污水和部分农业面源污染。采用单因子污染指数法、综合水质标识指数法和水体自净能力评价等方法，对莲花荡水系的水环境质量进行了现状评价，结果为：莲花荡水系在平水期和丰水期分别为严重污染和重度污染；综合水质标识类别介于Ⅴ类~劣Ⅴ类黑臭水质之间；水体具有一定的自净能力，且不同时期各河段的自净能力有所不同。 Lianhuadang River System, flowing down with the Wuxi Harbor River, is one of the most important inflow rivers of the West Taihu. Based on the standards of the water environment functional zoning, its water quality should meet the requirement of the Class-III surface water. In April 2014 (average season) and July (abundant season), the field investigation and sampling monitoring have been performed twice respectively in the Lianhuadang River System. The results show that: the contamination indexes in the water exceeding the standard of the Class-III surface water mainly are the permanganate index, the total phosphorus, the total nitrogen, the ammonia nitrogen and the chlorophyll A, of which the contamination of the nitrogen and phosphorus exceed the standard seriously. Due to the influence of the increasing stream flow in abundant season, the water quality in July is slightly better than that in April. According to the survey, the main pollution sources in the water are the waste water of the concentrating livestock and poultry breeding, the coastwise rural domestic sewage, and part of the Agricultural Area Source Pollution . Adopting the single factor contamination index method, the WQI method (the comprehensive water quality identification index method) and the water self-purification ability evaluation method, the results of the current situation evaluation for the water environmental quality of the Lianhuadang Water System show that: most rivers of the Lianhuadang Water System are polluted seriously; the comprehensive water quality identification category is ranged from Class V to inferior class V-stinking sewage; the water body has a certain self-purification ability, and the capacity of self-purification varies in different periods.

Nitrogen and oxygen isotopic compositions of water-soluble nitrate in Taihu Lake water system, China: implication for nitrate sources and biogeochemical process

The stable isotope nitrogen-15 (15N) is a robust indicator of nitrogen (N) source, and the joint use of δ15N and δ18O–NO3 − values can provide more useful information about nitrate source discrimination and N cycle process. The δ15N and δ18O–NO3 − values, as well as major ion tracers, from Taihu Lake in east China were investigated to identify the primary nitrate sources and assess nitrate biogeochemical process in the present study. The results show that the nitrate concentration in West Taihu Lake (WTL) was generally higher than those in East Taihu Lake (ETL) and its upstream inflow rivers. The NO3 −/Cl− value combined with mapping of δ15N–NO3 − and NO3 − concentration suggest that the mixing process should play a major effect in WTL, and denitrification was the dominant N transformation process in WTL. A linear relationship of close to ~1: 2 was observed between δ15N–NO3 − and δ18O–NO3 − values in WTL, confirming the occurrence of denitrification in WTL. The δ15N–NO3 − data imply that sewage and manure were the principal nitrate sources in WTL and its feeder rivers, while the nitrate in ETL might derive from soil organic nitrogen and atmospheric deposition. The δ18O–NO3 − data indicate most of nitrate from microbial nitrification of organic nitrogen matter possibly make a significant contribution to the lake.

Initial identification of heavy metals contamination in Taihu Lake, a eutrophic lake in China

A detailed investigation of seven heavy metals (Cu, Cd, Cr, As, Pb, Zn, Ni) in the water column, interstitial water and surface sediment was conducted to quantify the extent of their contamination in Taihu Lake. Results showed the average total concentrations ranged from 0.93 μg/L for Cd to 47.03 μg/L for Zn. The dissolved concentrations in the overlying water ranged from 0.06 μg/L for Cd to 15.86 μg/L for Zn. The metals in the Taihu Lake surface water were primarily in the particulate phase, especially for Cd, whose particulate concentration represented 94.3% of the total. In the surface sediment, the mean concentrations for Cr, Ni, Cu, Zn, As, Cd and Pb were 41.50, 28.72, 27.82, 65.46, 5.94, 0.82 and 41.17 mg/kg, respectively. The metals in the water column and sediments of Taihu Lake displayed significant spatial variations, and the higher metal concentrations mainly occurred in the north and west of Taihu Lake, especially in Zhushan Bay and West Taihu Lake. A quality assessment indicated that most of the metals in the surface water of Taihu Lake had no or low adverse health effects on organisms, except for Pb and Cu, which may cause chronic toxicity. Compared with the “Consensus-Based Sediment Quality Guidelines”, the polluting metals were Cr, Ni and Cd, and the polluted regions were confined to Zhushan Bay, Meiliang Bay and the west of Taihu Lake, especially for north of Zhushan Bay. The polluted areas for Cr, Ni and Cd were 14.36, 34.70 and 13.24 km2, respectively. We suggest that Cr, Ni, and Cd in the polluted areas should be addressed and that tissue chemistry and sediment toxicity assessments be performed as soon as possible.

Distribution and bioaccumulation of heavy metals in aquatic organisms of different trophic levels and potential health risk assessment from Taihu lake, China

Aquatic organisms of different trophic levels were taken from Taihu lake. Heavy metals (Cu, Zn, Cr, Ni, Cd, Pb) were measured in phytoplankton, zooplankton, in two species of zoobenthos, and in eight fish species, as well as in the water column and bottom sediments. Results showed that the concentration of Cu and Zn for all organisms was much higher than for other metals, and Cd was the lowest in all species. Generally, heavy metal concentrations in phytoplankton were higher than in zooplankton. In zoobenthos, the concentration in Bellamya sp.(human edible snail) was higher than that in Corbiculidae (bivalve). Metal concentrations had no significant difference between fish species but tended to be higher in predator fish such as Coilia ectenes and Erythroculter ilishaeformis than in herbivorous fish. The level of measured metals in Taihu fish was moderate-low compared with that of fresh water fishes from international results. Spatially, metal concentrations in organisms were higher in the north and west Taihu lake but lower in south and east lake and this appears to be related to river inputs that are heavily influenced by anthropogenic activities. The bio-concentration factor (BCF) for all aquatic organisms in the food chain indicated that it was generally highest in planktons, followed by zoobenthos, and lowest in fish. Health risk assessment and comparison with national and international standards showed that consumption of aquatic products from the lake was generally safe but fishermen were a higher risk group especially through dietary intake of Bellamya sp.

Multivariate Analysis of Interactions Between Phytoplankton Biomass and Environmental Variables in Taihu Lake, China

Phytoplankton variation in large shallow eutrophic lakes is characterized by high spatial and temporal heterogenity. Understanding the pattern of phytoplankton variation and the relationships between it and environmental variables can contribute to eutrophic lakes management. In this study Taihu Lake, one of the largest eutrophic fresh water lake in China, was taken as study area. The water body of Taihu Lake was divided into five regions viz. Wuli bay (WB), Meilian Bay (MB), West Taihu Lake (WTL), Main Body of Taihu Lake (MBTL) and East Taihu Lake (ETL). Concentrations of chlorophyll-a and the related environmental variables were determined in each region in the period 2000-2003. Factor analysis and multivariate analysis were applied to evaluate the interactions between phytoplankton variation and environmental variables. Results showed that the highest average concentrations of TN, TP and Chl-a were observed in WB, followed in a descending order by MB and WTL, and the lowest concentrations of TN, TP and Chl-a were observed in MBTL and ETL. Chl-a and TP concentrations in most regions (except ETL) declined during the study period. It suggested that to some extent the lake was recovering from eutrophication. However, persistent ascending of TN and NH(4)-N in all five regions indicated the deteriorating of water quality in the study period. Results of multivariate showed that the relationships between phytoplankton biomass and environmental variables varied among regions. TP illustrated itself a controlling role on phytoplankton in WB, MB, WTL and MBTL according to the significant positive relations to phytoplankton biomass in these regions. Nitrogen could be identified as a limiting factor to phytoplankton biomass in ETL in view of the positive correlations between TN and phytoplankton and between NH(4)-N and phytoplankton. Spatial variation of interactions between phytoplankton and environmental parameters suggested proper eutrophication control measures were needed to restore ecological system in each region of Taihu Lake.

Taihu Lake, lower Yangtze drainage basin: evolution, sedimentation rate and the sea level

The present study focuses on two Holocene sediment boreholes in Taihu Lake, sunk to examine the lake sediment including sedimentary texture and structure, microfossils, magnetic susceptibility and radiocarbon-dated Holocene stratigraphy. Results demonstrate that the early Taihu Lake area consisted primarily of West Taihu Lake depression and a low floodplain in the East Taihu Lake area. No hydraulic connection existed between the two sectors during the early Holocene when sea level stood at lower level. Core sediments, microfossil and magnetic evidence records that West Taihu Lake began to be inundated by brackish water prior to 6000 years ago, while East Taihu Lake still remained a freshwater setting. After 6000 B.P., a further rise in freshwater table in response to sea-level fluctuation progressively drowned the entire lake, coalescing the two parts after 4600–3500 B.P. Our coring revealed that the lacustrine sediment began to form in West Taihu Lake as early as 11,000 years ago, while it happened much later (only after 5700 B.P.) to form in East Taihu Lake. High sedimentation rates (0.42–0.35 mm/year) in lacustrine deposits of West Taihu Lake occurred between ~11,000 and 5000 B.P. In contrast, the high sedimentation rates (1.54 mm/year) in East Taihu Lake occurred only within a very short time period, from ~6500 to 5500 B.P. Since then, sedimentation rates have decelerated to a very low value (<0.10 mm/year) in both West and East Taihu Lakes. The low sedimentation rate of West and East Taihu Lake of the middle and late Holocene explains the deceleration of the sea-level rising after 5500 B.P. and the rapid coastal progradation seaward.

Amino Acids and Stable Carbon Isotope Distributions in Taihu Lake, China, Over the Last 15,000 Years, and Their Paleoecological Implications

Amino acid, organic nitrogen, and stable carbon isotope (13C/12C) profiles through a core from East Taihu Lake are interpreted in terms of paleoecology and paleoclimate over the last ca. 15,000 yr. Lower amino acid contents and higher δ13C values at the base of the core represent a cool and arid climate, and coincide with low organic productivity. A marked increase in total amino acids and organic nitrogen, with a decrease in δ13C values from 193 to 90 cm (ca. 6500–6000 yr B.P.), indicates a warmer and moist climate, and greater organic productivity. Amino acids then decrease in abundance, while δ13C values increase progressively, beginning at 73 cm (ca. 6000 yr B.P.), reflecting cooling and lower organic productivity. The average δ13C values from a core from West Taihu Lake are evidently higher than values from East Taihu Lake. The latter may reflect a stream environment, whereas the high δ13C values from West Taihu Lake likely reflect autotrophic carbon sources and a lacustrine environment since 11,000 yr B.P.

A 14 000-year record of paleoenvironmental change in the western basin of China's third largest lake, Lake Taihu

The longest vertical profile from the western basin of Taihu Lake ever taken was nearly 4 m (396 cm) in length and represented a time period of over 14 000 years. The core was analyzed for the following proxies, magnetic susceptibility, organic carbon isotope, total organic carbon, total nitrogen, total pigments, saturated hydrocarbons, carbon 14, thermolytic hydrogen (the hydrogen index, HI) and foraminifera. Results from the west Taihu lake core indicate that ca. 14 300–13 400 a B.P., the lake was relatively shallow and the climate was likely to have been quite arid. From 13 400 to 12 400 a B.P., the environment became less arid and the depth of the water in Lake Taihu increased. Marine incursions occurred during this period as indicated by the presence of numerous marine foraminifera. From ca. 12 400 to 10 900 a B.P., the climate became wetter, warmer and more variable. A cold dry period occurred around ca. 11 500 a B.P., causing the lake to become more shallow. From 10 900 to 10 000 a B.P., a warm and wet period reasserted itself and water depth again increased. A cold dry period reoccurred from 10 000 to 9500 a B. P. From 9500 to 7200 a B.P., the climate was quite variable. By 7200–5700 a B.P., the climate again turned warmer and wetter. Some of the major sediment proxies used in this study changed dramatically at ca. 5050 a B.P., reflecting changes in material source and a probable interruption of sedimentation. The modern environment (4900 aB.P.-present) was characterized by a well oxidized sediment layer and thriving algae. The lake is presently very eutrophic and is characterized by cyanobacteria, primarily Microcystis aeruginosa, the dominant primary producer in the lake. This is the first study to use a variety of organic geochemical proxies to infer paleoenvironmental changes in Taihu Lake.

Evidence for an aquatic plant origin of ketones found in Taihu Lake sediments

This is the first time that aquatic plants have been singled out as the major source of alkan-2-ones in the sediments of a freshwater lake. Formerly alkan-2-ones were regarded as products of microbiological oxidation of corresponding alkanes or β-oxidation and decarboxylation of fatty acids. The presence of alkan-2-ones in both the cyanobacteria, high aquatic plants and sediments of Taihu Lake in the eastern China is viewed as evidence for the biogenic origin of these compounds. Taihu Lake is one of the largest freshwater lakes in China. The dominant species in the West Taihu Basin is blue-green algae; the East Taihu Basin is covered by vascular plants. We have analyzed the ketones and saturated hydrocarbons in the surficial sediments and in plant samples from Taihu Lake. We found that the distribution models of alkan-2-ones in the sediment samples from Taihu Lake were very similar to those that we found in the aquatic plants from the lake's western and eastern basins. The western basin interrelation coefficient was 0.91 and the Eastern Basin interrelation coefficients were 0.80 and 0.75 for emergent plants and submergent plants, respectively. These are shown as the similar major carbon peaks, L/H, OEP and high abundance of 6,10,14-trimethylpentadecan-2-one etc. But there are poor relationships between the alkan-2-ones in the sediment with corresponding the normal alkanes in the sediment of West Taihu Basin (interrelation coefficient is 0.68) and in the East Taihu Basin (interrelation coefficient is 0.41). The alkan-2-ones of the surficial sediment in the West Taihu Basin are from blue-green algae and in the East Taihu basin are from vascular plants. The different distributions of sediment alkan-2-ones in the two basins are possible to be used as an indicator of algae-type and macrophyte-type lakes.

The Summer Phytoplankton Species Composition in Northern Part of West Taihu Lake

The Summer Phytoplankton Species Composition in Northern Part of West Taihu Lake

Distinguishing Lake Types of East Taihu Lake and West Taihu Lake by Biological Markers

The methods and analytical results for distinguishing lake types of East Taihu Lake and West Taihu Lake by biological markers were dealt in this paper.;The methods and analytical results for distinguishing lake types of East Taihu Lake and West Taihu Lake by biological markers were dealt in this paper.

Paleoenvironmental implication of magnetic measurements on sediment cores from Taihu Lake, east China

本文以太湖沉积物为研究对象,试图在磁性测量的基础上,对太湖湖区四个样芯进行分层,建立样芯间层位对应联系,并结合孢粉、粒度、地球化学和有机质含量等分析测定,从沉积物样芯的磁参数曲线变化中提取该地区的环境变化信息。研究结果表明,由于该方法具有快速简便、经济易行、无破坏等优点,从而可能对样芯作连续测量,以提取高分辨率的环境变化信息。在湖泊沉积物的研究中有着独到的作用,可作为地球化学、孢粉、微体古生物、粒度等分析测试的辅助手段和先导。;Taihu Lake is a large shallow lake on the southern deltaic plain of the Yangtze River An irLerdiscipline study is carried out on about two-meter-long sediment cores taken from this lake to retrieve high resolution information on Holocene environmental change in Taihu Lake region. Mineral magnetic measurement, as the precursor, has been made on three cores from vvest Taihu Lake and one core from east Taihu Lake, which is used for sediment stratigraphy, bulk lithological classification and core-core correlation. These results are set alongside those derived from geochemical, pollen and granulometric analysis to reconstruct the environmental seccesses recorded in the radiocarbon dated sediment column. For cores TM2, TM3 and Wl-6 from west Taihu Lake, three distinctive stratigraphic horizons have been identified on the basis of the magnetic measurements and they are correlated among the cores. These divisions are coincident with the variation of pollen assemblages, indicating different climatic periods In the Yangtze River Delta. It is suggested that the low part of these cores is the early Holocene sediments, when the climate became wanmar sea level rose and Taihu Lake appeared as several small separated lakes. There is no stable continued deposit at west Taihu since the large lake formed in mid-Holocene as the result of current erosion. At east Taihu, the sediment column recorded some detailed information on palaeoenvironmental changes, as it is a relatively small and closed bay. The study shows that rof magnetic parameters in core EU 1 are mainly resulted from changes in particle size constitution, implying the shifts of sedimentary environment in response to the climatic changes.