A total of 30 surface sediments samples from the estuary wetland of the Tangxi River, Chaohu Lake Basin were obtained and tested. Enrichment factor （EF） and geoaccumulation index （Igeo） as well as multivariate sta...A total of 30 surface sediments samples from the estuary wetland of the Tangxi River, Chaohu Lake Basin were obtained and tested. Enrichment factor （EF） and geoaccumulation index （Igeo） as well as multivariate statistical analysis methods including Factor Analysis （FA） and Hierarchical Cluster Analysis （HCA） were applied for the assessment of heavy metal pollution in surface sediments. The results of EF values show that the pollution of copper （Cu） and cadmium （Cd） occurs in the estuarine sediments, and that zinc （Zn）, lead （Pb） and chrome （Cr） may originate from crustal materials or natural weathering process. The mean EF values of the five heavy metals are in the decreasing order： Cu〉Cd）Zn〉Pb〉Cr. Based on the lgeo of target heavy metals, the surface sediments collected from the study area can be approximately categorized as unpolluted with Zn, Pb and Cr, and moderately polluted with Cu and Cd. The degree of heavy metal pollution decreases in the order of Cu〉Cd〉Zn〉Pb〉Cr. Three groups of pollution factors are presented from FA： Zn-TOC, Cu-Cd and Cr-Pb, which respectively accounte for 27.22%, 25.20% and 21.05% of variance. By means of HCA, a total number of seven groups are distinguished from 30 sampling sites. Results indicate that Cu and Cd are the prior controlled pollutants in the estuarine sediments of the Tangxi River.展开更多
Flood is one kind of unexpected and the most common natural disasters, which is affected by many factors and has complex mechanism. At home and abroad, there is still no mature theory and method used for the long-term...Flood is one kind of unexpected and the most common natural disasters, which is affected by many factors and has complex mechanism. At home and abroad, there is still no mature theory and method used for the long-term forecast of natural precipitation at present. In the present paper the disadvantages of grey GM (1, 1) and Markov chain are ana- lyzed, and Grey-Markov forecast theory about flood is put forward and then the modifying model is developed by making prediction of Chaohu Lake basin. Hydrological law was conducted based on the theoretical forecasts by grey system GM (1, 1) forecast model with improved Markov chain. The above method contained Stat-analysis, embodying scientific approach, precise forecast and its reliable results.展开更多
A typical lake sediment core is obtained from the Chaohu Lake in the lower reaches of the Yangtze River,Anhui Province,China.The timing scale is constrained by AMS 14 C dating method.Climate proxies such as pollen and...A typical lake sediment core is obtained from the Chaohu Lake in the lower reaches of the Yangtze River,Anhui Province,China.The timing scale is constrained by AMS 14 C dating method.Climate proxies such as pollen and grain size in the core are analyzed to reconstruct the environment changes at this site approximately between 9870 and 2170 cal.a BP.The results indicate that at the research area, the climate in the early-middle Holocene had evolved through 3 stages.From 9870 to 6040 cal.a BP, proxy records show a warm and dry climate with low water levels after the late-glacial period.During this stage,cool and dry events occurred at about 8910 and 6060-6030 cal.a BP.Then,between 6040 and 4860 cal.a BP,the climate was humid and vegetation was more flourishing in the Chaohu Lake Valley.The Holocene Optimum occurred at 5840-5500 cal.a BP in the Chaohu Lake,showing the best condition of water and heat.Elm Decline occurred at the period of 5380-4930 cal.a BP.Since 4860 cal.a BP,the climate was warm and dry through 2170 cal.a BP as shown in both pollen spectrum and grain-size histories.Two obvious dry events occurred in 3760 and 2170 cal.a BP,respectively.At 2170 cal.a BP,the water level of the Chaohu Lake reached the lowest as the lakebed possibly exposed. Such lake sediment observations are consistent with the historical records in this area.展开更多
基金Under the auspices of the Key Technology R&D Program of Anhui Province,China (No. 07010302165)
文摘A total of 30 surface sediments samples from the estuary wetland of the Tangxi River, Chaohu Lake Basin were obtained and tested. Enrichment factor （EF） and geoaccumulation index （Igeo） as well as multivariate statistical analysis methods including Factor Analysis （FA） and Hierarchical Cluster Analysis （HCA） were applied for the assessment of heavy metal pollution in surface sediments. The results of EF values show that the pollution of copper （Cu） and cadmium （Cd） occurs in the estuarine sediments, and that zinc （Zn）, lead （Pb） and chrome （Cr） may originate from crustal materials or natural weathering process. The mean EF values of the five heavy metals are in the decreasing order： Cu〉Cd）Zn〉Pb〉Cr. Based on the lgeo of target heavy metals, the surface sediments collected from the study area can be approximately categorized as unpolluted with Zn, Pb and Cr, and moderately polluted with Cu and Cd. The degree of heavy metal pollution decreases in the order of Cu〉Cd〉Zn〉Pb〉Cr. Three groups of pollution factors are presented from FA： Zn-TOC, Cu-Cd and Cr-Pb, which respectively accounte for 27.22%, 25.20% and 21.05% of variance. By means of HCA, a total number of seven groups are distinguished from 30 sampling sites. Results indicate that Cu and Cd are the prior controlled pollutants in the estuarine sediments of the Tangxi River.
基金Under the auspices of the National Natural Science Foundation of China (No. 40571162)the Natural Science Foun-dation of Anhui Province (No. 050450401)
文摘Flood is one kind of unexpected and the most common natural disasters, which is affected by many factors and has complex mechanism. At home and abroad, there is still no mature theory and method used for the long-term forecast of natural precipitation at present. In the present paper the disadvantages of grey GM (1, 1) and Markov chain are ana- lyzed, and Grey-Markov forecast theory about flood is put forward and then the modifying model is developed by making prediction of Chaohu Lake basin. Hydrological law was conducted based on the theoretical forecasts by grey system GM (1, 1) forecast model with improved Markov chain. The above method contained Stat-analysis, embodying scientific approach, precise forecast and its reliable results.
基金Supported by the National Natural Science Foundation of China(Grant No.40571162)the Key Project of the National Natural Science Foundation of China(Grant No.90411015)the Natural Science Foundation of Anhui Province(GrantNo.050450401)
文摘A typical lake sediment core is obtained from the Chaohu Lake in the lower reaches of the Yangtze River,Anhui Province,China.The timing scale is constrained by AMS 14 C dating method.Climate proxies such as pollen and grain size in the core are analyzed to reconstruct the environment changes at this site approximately between 9870 and 2170 cal.a BP.The results indicate that at the research area, the climate in the early-middle Holocene had evolved through 3 stages.From 9870 to 6040 cal.a BP, proxy records show a warm and dry climate with low water levels after the late-glacial period.During this stage,cool and dry events occurred at about 8910 and 6060-6030 cal.a BP.Then,between 6040 and 4860 cal.a BP,the climate was humid and vegetation was more flourishing in the Chaohu Lake Valley.The Holocene Optimum occurred at 5840-5500 cal.a BP in the Chaohu Lake,showing the best condition of water and heat.Elm Decline occurred at the period of 5380-4930 cal.a BP.Since 4860 cal.a BP,the climate was warm and dry through 2170 cal.a BP as shown in both pollen spectrum and grain-size histories.Two obvious dry events occurred in 3760 and 2170 cal.a BP,respectively.At 2170 cal.a BP,the water level of the Chaohu Lake reached the lowest as the lakebed possibly exposed. Such lake sediment observations are consistent with the historical records in this area.
