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Location map of Taibai Lake and core site. 

Location map of Taibai Lake and core site. 

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Element content, grain size, pollen and 210Pb dating analysis were performed on 80 cm sediment core from Taibai Lake, a shallow lake in the middle reach of Yangtze River in China, to reveal the response of catchment environment to climate changes and human activities during the past four centuries. The 210Pb dating suggests that 0-39.5 cm of the co...

Contexts in source publication

Context 1
... Lake lies to the north of Yangtze River and the south foot of Dabie Mountain (Fig. 1), where was the ancient Penglize Lake in early Holocene ( Qu et al., 1998). The catchment area of Taibai Lake was 607 km 2 , and the surface area was 28.98 km 2 in 2002. The average water depth of Taibai Lake is 3.2 m in recent years, with Vallisneria denseserrulata as the main submerged macrophyte ( Jian et al., 2001). The main inflow ...
Context 2
... influencing Taibai Lake and catchment environment were the construction of water conservancy facilities and land reclamation around the lake. In order to facilitate the agricultural irrigation and flood control, three reservoirs were built in the upper reach of Taibai Lake in 1958-1962 AD, such as Jingzhu, Kaotian and Xianrenba reservoirs (Fig. 1). Correspondingly, land reclamation around Taibai Lake flourished since late 1950s. The area of Taibai Lake was 69.2 km 2 in 1930s ( Wang and Dou, 1998). It was 63.70 km 2 , with the water area of 60.10 km 2 in mid- 1950s. Nevertheless, the water area shrunk to 40.01 km 2 by mid-1960s due to land reclamation, decreased 33.4% compared ...
Context 3
... sediment cores (TB-03) about 80 cm long were taken at the deeper area of Taibai Lake with a piston corer in 2003 ( Fig. 1). The core sediments were sub- sampled at a 0.5 cm resolution for 0-50 cm and 1 cm resolution for 50-80 cm. The sub-samples were sealed in plastic bags to be transported to ...
Context 4
... reconstruction of climate and environment changes is essential to understand the impact of natural processes and human activities on the ecosystems. It is especially contributive in the middle and lower reaches of Yangtze River in China. Yangtze River catchment, a sensitive area to climate changes and human activities (Chen et al., 2001; Du et al., 2001; Gao et al., 2004; Liu, 2000; Liu et al., 2000; Xiang et al., 2002; Yasuda et al., 2004; Yin and Li, 2001), was the economic developed, population denseness area in China for thousands of years (Zhang, 1990; Zhang et al., 2005). The development in economy and increase in population in recent decades had exerted great pressure on the ecological environment, especially water pollution, soil loss, siltation on lake and river bed, and lake ecological degeneration in the middle and lower reaches of Yangtze River (Du et al., 2001; Xiang et al., 2002; Yin and Li, 2001; Yang et al., 2002a). In comparison to the environment evolution at millennium scale, there had rapid population increase and frequent climate fluctuation during the last hundreds years (Zhang, 1980, 1990; Yang et al., 2002b), linking closely with current ecological environment. But seldom study was performed on this time scale, especially linking sedimentary and historical records to interpret the ecological environment evolution. It is challenging due to the difficulties obtaining sedimentary records of sufficient temporal resolution and chrono- logical accuracy, and corresponding documentary data. Lake sediments, as the excellent archives of regional environment changes, have the characteristics of conti- nuity, high resolution and abundant information, are playing a more important role in the research on regional human activities and environment change reconstruction (Liu et al., 2000; Huang and Connell, 2000; Tibby, 2003). In this study, the environment response to climate changes and human activities was reconstructed for Taibai Lake catchment, by the systemic analyses of the physical, element geochemistry and pollen proxies in sediment core of Taibai Lake, and the sequential information of population and plantation records in Susong County since 17th century, and indirect climate records in the middle and lower reaches of Yangtze River. Taibai Lake lies to the north of Yangtze River and the south foot of Dabie Mountain (Fig. 1), where was the ancient Penglize Lake in early Holocene (Qu et al., 1998). The catchment area of Taibai Lake was 607 km 2 , and the surface area was 28.98 km 2 in 2002. The average water depth of Taibai Lake is 3.2 m in recent years, with Vallisneria denseserrulata as the main submerged macrophyte (Jian et al., 2001). The main inflow rivers of Taibai Lake are in the north of its catchment, and the water drains into Longgan Lake from the outlet southeast of Taibai Lake. The pH of Taibai Lake water is 7.4 – 8.0 and the degree of mineralization is 65 – 112 mg/L. Its hydro- chemical type is of carbonate calcium, with main cations Ca 2+ , Mg 2+ , Na + + K + and main anions HCO 3 − , SO 4 2 − and Cl − , the average concentrations of which are 20.0 mg/L, 3.65 mg/L, 2.97 mg/L and 45.0 mg/L, 3.65 mg/L and 2.67 mg/L respectively (Wang and Dou, 1998). It is characterized by a subtropical monsoon climate in Taibai Lake catchment as well as in the middle and lower reaches of Yangtze River, with mean annual precipitation 1273 mm concentrating in summer (June – September), mean annual evaporation 1041 mm. The zonal vegetation in the catchment should be evergreen broad-leaved forest; nevertheless, it had been destroyed and substituted by secondary vegetations (mainly pines). Susong County, lies to the northeast of Taibai Lake, was one of the established district since 598 AD, with relatively changeless administrative boundaries since 1645 AD (Annals of Susong County, 1935). The population, plantation scale, and historical events, though not continuous annually, were systematically collected from the Annals of Susong County (1935) by the authors for the first time, and the statistics in recent 50 years were also used in this paper (Fig. 2). The population of Susong County was about eighty thousand in 1590 – 1670 AD, it was one hundred and forty thousand in 1712 AD and up to three hundred and ninety thousand in 1772 AD (Fig. 2). Thus, the rapid population increase in Susong County was from late 17th century to mid 18th century. Nevertheless, the population decreased rapidly since 1810s and reduced to one hundred and eighty thousand in 1868 AD mainly due to the war dead of peasant uprising, such as the Taiping Heavenly Kingdom (Annals of Susong County, 1935). The population increased slightly in late 19th century, but was still less than that in late 18th century. The cultivation scale in Susong County, mainly rice, wheat and sweet potato (Annals of Susong County, 1935), increased by three folds from late 17th century to late 18th century and then decreased to the level in late 17th century, coincidently with population changes (Fig. 2). In order to understand the variations of population and cultivation in Susong County, the dynasty subrogation for China should be introduced. Ming Dynasty was in 1368 – 1644 AD, and Qing Dynasty was in 1644 – 1911. The population increased slowly from North Song Dynasty (960 – 1127) to mid Ming Dynasty, which was between 20 million and 100 million in China (Ding, 1993). The rapid population increase was in Qing Dynasty, it was up to 400 million in 1820s from 100 million in mid 17th century in China (Ding, 1993). It can be seen that, population variation in Susong County in Qing Dynasty was not a especial case, it was consistent with that of China. Human activities influencing Taibai Lake and catchment environment were the construction of water conservancy facilities and land reclamation around the lake. In order to facilitate the agricultural irrigation and flood control, three reservoirs were built in the upper reach of Taibai Lake in 1958 – 1962 AD, such as Jingzhu, Kaotian and Xianrenba reservoirs (Fig. 1). Correspondingly, land reclamation around Taibai Lake flourished since late 1950s. The area of Taibai Lake was 69.2 km 2 in 1930s (Wang and Dou, 1998). It was 63.70 km 2 , with the water area of 60.10 km 2 in mid- 1950s. Nevertheless, the water area shrunk to 40.01 km 2 by mid-1960s due to land reclamation, decreased 33.4% compared with that in mid-1950s, reducing at a rate of 2.0 km 2 annually. The water area was only 27.02 km 2 in 1978 AD, decreased 32.5% compared with that in mid- 1960s, reducing at a rate of 1.08 km 2 annually. The area of Taibai Lake changed little since 1978 AD (Fig. 3). Climate change is one of the main factors influencing catchment environment and human activities (Stebich et al., 2005). Here, the temperature change in the middle reach of Yangtze River during the last 450 years is shown in Fig. 2, which was deduced mainly from chorography by Ye and Zhao (1994) and Zhang (1980). There were two cold stages during the “ Little Ice Age ” in the studied period, one was 1650s – 1700s and the other was 1790s – 1900s (Fig. 2). The annual average temperatures for the two cold periods were 0.55 °C and 0.58 °C lower than that in 1900 – 1979 AD. Since the end of the “ Little Ice Age ” , the temperature increased rapidly and plentiful precipitation occurred in 1900 – 1920s (Fig. 9) (Gong et al., 2001). The sediment cores (TB-03) about 80 cm long were taken at the deeper area of Taibai Lake with a piston corer in 2003 (Fig. 1). The core sediments were sub- sampled at a 0.5 cm resolution for 0 – 50 cm and 1 cm resolution for 50 – 80 cm. The sub-samples were sealed in plastic bags to be transported to laboratory. The frozen dried samples were used for Pb dating, TOC, TN, and metal element analysis. The wet samples were used for grain size and pollen analysis. The main methods used were as ...
Context 5
... reconstruction of climate and environment changes is essential to understand the impact of natural processes and human activities on the ecosystems. It is especially contributive in the middle and lower reaches of Yangtze River in China. Yangtze River catchment, a sensitive area to climate changes and human activities (Chen et al., 2001; Du et al., 2001; Gao et al., 2004; Liu, 2000; Liu et al., 2000; Xiang et al., 2002; Yasuda et al., 2004; Yin and Li, 2001), was the economic developed, population denseness area in China for thousands of years (Zhang, 1990; Zhang et al., 2005). The development in economy and increase in population in recent decades had exerted great pressure on the ecological environment, especially water pollution, soil loss, siltation on lake and river bed, and lake ecological degeneration in the middle and lower reaches of Yangtze River (Du et al., 2001; Xiang et al., 2002; Yin and Li, 2001; Yang et al., 2002a). In comparison to the environment evolution at millennium scale, there had rapid population increase and frequent climate fluctuation during the last hundreds years (Zhang, 1980, 1990; Yang et al., 2002b), linking closely with current ecological environment. But seldom study was performed on this time scale, especially linking sedimentary and historical records to interpret the ecological environment evolution. It is challenging due to the difficulties obtaining sedimentary records of sufficient temporal resolution and chrono- logical accuracy, and corresponding documentary data. Lake sediments, as the excellent archives of regional environment changes, have the characteristics of conti- nuity, high resolution and abundant information, are playing a more important role in the research on regional human activities and environment change reconstruction (Liu et al., 2000; Huang and Connell, 2000; Tibby, 2003). In this study, the environment response to climate changes and human activities was reconstructed for Taibai Lake catchment, by the systemic analyses of the physical, element geochemistry and pollen proxies in sediment core of Taibai Lake, and the sequential information of population and plantation records in Susong County since 17th century, and indirect climate records in the middle and lower reaches of Yangtze River. Taibai Lake lies to the north of Yangtze River and the south foot of Dabie Mountain (Fig. 1), where was the ancient Penglize Lake in early Holocene (Qu et al., 1998). The catchment area of Taibai Lake was 607 km 2 , and the surface area was 28.98 km 2 in 2002. The average water depth of Taibai Lake is 3.2 m in recent years, with Vallisneria denseserrulata as the main submerged macrophyte (Jian et al., 2001). The main inflow rivers of Taibai Lake are in the north of its catchment, and the water drains into Longgan Lake from the outlet southeast of Taibai Lake. The pH of Taibai Lake water is 7.4 – 8.0 and the degree of mineralization is 65 – 112 mg/L. Its hydro- chemical type is of carbonate calcium, with main cations Ca 2+ , Mg 2+ , Na + + K + and main anions HCO 3 − , SO 4 2 − and Cl − , the average concentrations of which are 20.0 mg/L, 3.65 mg/L, 2.97 mg/L and 45.0 mg/L, 3.65 mg/L and 2.67 mg/L respectively (Wang and Dou, 1998). It is characterized by a subtropical monsoon climate in Taibai Lake catchment as well as in the middle and lower reaches of Yangtze River, with mean annual precipitation 1273 mm concentrating in summer (June – September), mean annual evaporation 1041 mm. The zonal vegetation in the catchment should be evergreen broad-leaved forest; nevertheless, it had been destroyed and substituted by secondary vegetations (mainly pines). Susong County, lies to the northeast of Taibai Lake, was one of the established district since 598 AD, with relatively changeless administrative boundaries since 1645 AD (Annals of Susong County, 1935). The population, plantation scale, and historical events, though not continuous annually, were systematically collected from the Annals of Susong County (1935) by the authors for the first time, and the statistics in recent 50 years were also used in this paper (Fig. 2). The population of Susong County was about eighty thousand in 1590 – 1670 AD, it was one hundred and forty thousand in 1712 AD and up to three hundred and ninety thousand in 1772 AD (Fig. 2). Thus, the rapid population increase in Susong County was from late 17th century to mid 18th century. Nevertheless, the population decreased rapidly since 1810s and reduced to one hundred and eighty thousand in 1868 AD mainly due to the war dead of peasant uprising, such as the Taiping Heavenly Kingdom (Annals of Susong County, 1935). The population increased slightly in late 19th century, but was still less than that in late 18th century. The cultivation scale in Susong County, mainly rice, wheat and sweet potato (Annals of Susong County, 1935), increased by three folds from late 17th century to late 18th century and then decreased to the level in late 17th century, coincidently with population changes (Fig. 2). In order to understand the variations of population and cultivation in Susong County, the dynasty subrogation for China should be introduced. Ming Dynasty was in 1368 – 1644 AD, and Qing Dynasty was in 1644 – 1911. The population increased slowly from North Song Dynasty (960 – 1127) to mid Ming Dynasty, which was between 20 million and 100 million in China (Ding, 1993). The rapid population increase was in Qing Dynasty, it was up to 400 million in 1820s from 100 million in mid 17th century in China (Ding, 1993). It can be seen that, population variation in Susong County in Qing Dynasty was not a especial case, it was consistent with that of China. Human activities influencing Taibai Lake and catchment environment were the construction of water conservancy facilities and land reclamation around the lake. In order to facilitate the agricultural irrigation and flood control, three reservoirs were built in the upper reach of Taibai Lake in 1958 – 1962 AD, such as Jingzhu, Kaotian and Xianrenba reservoirs (Fig. 1). Correspondingly, land reclamation around Taibai Lake flourished since late 1950s. The area of Taibai Lake was 69.2 km 2 in 1930s (Wang and Dou, 1998). It was 63.70 km 2 , with the water area of 60.10 km 2 in mid- 1950s. Nevertheless, the water area shrunk to 40.01 km 2 by mid-1960s due to land reclamation, decreased 33.4% compared with that in mid-1950s, reducing at a rate of 2.0 km 2 annually. The water area was only 27.02 km 2 in 1978 AD, decreased 32.5% compared with that in mid- 1960s, reducing at a rate of 1.08 km 2 annually. The area of Taibai Lake changed little since 1978 AD (Fig. 3). Climate change is one of the main factors influencing catchment environment and human activities (Stebich et al., 2005). Here, the temperature change in the middle reach of Yangtze River during the last 450 years is shown in Fig. 2, which was deduced mainly from chorography by Ye and Zhao (1994) and Zhang (1980). There were two cold stages during the “ Little Ice Age ” in the studied period, one was 1650s – 1700s and the other was 1790s – 1900s (Fig. 2). The annual average temperatures for the two cold periods were 0.55 °C and 0.58 °C lower than that in 1900 – 1979 AD. Since the end of the “ Little Ice Age ” , the temperature increased rapidly and plentiful precipitation occurred in 1900 – 1920s (Fig. 9) (Gong et al., 2001). The sediment cores (TB-03) about 80 cm long were taken at the deeper area of Taibai Lake with a piston corer in 2003 (Fig. 1). The core sediments were sub- sampled at a 0.5 cm resolution for 0 – 50 cm and 1 cm resolution for 50 – 80 cm. The sub-samples were sealed in plastic bags to be transported to laboratory. The frozen dried samples were used for Pb dating, TOC, TN, and metal element analysis. The wet samples were used for grain size and pollen analysis. The main methods used were as ...
Context 6
... reconstruction of climate and environment changes is essential to understand the impact of natural processes and human activities on the ecosystems. It is especially contributive in the middle and lower reaches of Yangtze River in China. Yangtze River catchment, a sensitive area to climate changes and human activities (Chen et al., 2001; Du et al., 2001; Gao et al., 2004; Liu, 2000; Liu et al., 2000; Xiang et al., 2002; Yasuda et al., 2004; Yin and Li, 2001), was the economic developed, population denseness area in China for thousands of years (Zhang, 1990; Zhang et al., 2005). The development in economy and increase in population in recent decades had exerted great pressure on the ecological environment, especially water pollution, soil loss, siltation on lake and river bed, and lake ecological degeneration in the middle and lower reaches of Yangtze River (Du et al., 2001; Xiang et al., 2002; Yin and Li, 2001; Yang et al., 2002a). In comparison to the environment evolution at millennium scale, there had rapid population increase and frequent climate fluctuation during the last hundreds years (Zhang, 1980, 1990; Yang et al., 2002b), linking closely with current ecological environment. But seldom study was performed on this time scale, especially linking sedimentary and historical records to interpret the ecological environment evolution. It is challenging due to the difficulties obtaining sedimentary records of sufficient temporal resolution and chrono- logical accuracy, and corresponding documentary data. Lake sediments, as the excellent archives of regional environment changes, have the characteristics of conti- nuity, high resolution and abundant information, are playing a more important role in the research on regional human activities and environment change reconstruction (Liu et al., 2000; Huang and Connell, 2000; Tibby, 2003). In this study, the environment response to climate changes and human activities was reconstructed for Taibai Lake catchment, by the systemic analyses of the physical, element geochemistry and pollen proxies in sediment core of Taibai Lake, and the sequential information of population and plantation records in Susong County since 17th century, and indirect climate records in the middle and lower reaches of Yangtze River. Taibai Lake lies to the north of Yangtze River and the south foot of Dabie Mountain (Fig. 1), where was the ancient Penglize Lake in early Holocene (Qu et al., 1998). The catchment area of Taibai Lake was 607 km 2 , and the surface area was 28.98 km 2 in 2002. The average water depth of Taibai Lake is 3.2 m in recent years, with Vallisneria denseserrulata as the main submerged macrophyte (Jian et al., 2001). The main inflow rivers of Taibai Lake are in the north of its catchment, and the water drains into Longgan Lake from the outlet southeast of Taibai Lake. The pH of Taibai Lake water is 7.4 – 8.0 and the degree of mineralization is 65 – 112 mg/L. Its hydro- chemical type is of carbonate calcium, with main cations Ca 2+ , Mg 2+ , Na + + K + and main anions HCO 3 − , SO 4 2 − and Cl − , the average concentrations of which are 20.0 mg/L, 3.65 mg/L, 2.97 mg/L and 45.0 mg/L, 3.65 mg/L and 2.67 mg/L respectively (Wang and Dou, 1998). It is characterized by a subtropical monsoon climate in Taibai Lake catchment as well as in the middle and lower reaches of Yangtze River, with mean annual precipitation 1273 mm concentrating in summer (June – September), mean annual evaporation 1041 mm. The zonal vegetation in the catchment should be evergreen broad-leaved forest; nevertheless, it had been destroyed and substituted by secondary vegetations (mainly pines). Susong County, lies to the northeast of Taibai Lake, was one of the established district since 598 AD, with relatively changeless administrative boundaries since 1645 AD (Annals of Susong County, 1935). The population, plantation scale, and historical events, though not continuous annually, were systematically collected from the Annals of Susong County (1935) by the authors for the first time, and the statistics in recent 50 years were also used in this paper (Fig. 2). The population of Susong County was about eighty thousand in 1590 – 1670 AD, it was one hundred and forty thousand in 1712 AD and up to three hundred and ninety thousand in 1772 AD (Fig. 2). Thus, the rapid population increase in Susong County was from late 17th century to mid 18th century. Nevertheless, the population decreased rapidly since 1810s and reduced to one hundred and eighty thousand in 1868 AD mainly due to the war dead of peasant uprising, such as the Taiping Heavenly Kingdom (Annals of Susong County, 1935). The population increased slightly in late 19th century, but was still less than that in late 18th century. The cultivation scale in Susong County, mainly rice, wheat and sweet potato (Annals of Susong County, 1935), increased by three folds from late 17th century to late 18th century and then decreased to the level in late 17th century, coincidently with population changes (Fig. 2). In order to understand the variations of population and cultivation in Susong County, the dynasty subrogation for China should be introduced. Ming Dynasty was in 1368 – 1644 AD, and Qing Dynasty was in 1644 – 1911. The population increased slowly from North Song Dynasty (960 – 1127) to mid Ming Dynasty, which was between 20 million and 100 million in China (Ding, 1993). The rapid population increase was in Qing Dynasty, it was up to 400 million in 1820s from 100 million in mid 17th century in China (Ding, 1993). It can be seen that, population variation in Susong County in Qing Dynasty was not a especial case, it was consistent with that of China. Human activities influencing Taibai Lake and catchment environment were the construction of water conservancy facilities and land reclamation around the lake. In order to facilitate the agricultural irrigation and flood control, three reservoirs were built in the upper reach of Taibai Lake in 1958 – 1962 AD, such as Jingzhu, Kaotian and Xianrenba reservoirs (Fig. 1). Correspondingly, land reclamation around Taibai Lake flourished since late 1950s. The area of Taibai Lake was 69.2 km 2 in 1930s (Wang and Dou, 1998). It was 63.70 km 2 , with the water area of 60.10 km 2 in mid- 1950s. Nevertheless, the water area shrunk to 40.01 km 2 by mid-1960s due to land reclamation, decreased 33.4% compared with that in mid-1950s, reducing at a rate of 2.0 km 2 annually. The water area was only 27.02 km 2 in 1978 AD, decreased 32.5% compared with that in mid- 1960s, reducing at a rate of 1.08 km 2 annually. The area of Taibai Lake changed little since 1978 AD (Fig. 3). Climate change is one of the main factors influencing catchment environment and human activities (Stebich et al., 2005). Here, the temperature change in the middle reach of Yangtze River during the last 450 years is shown in Fig. 2, which was deduced mainly from chorography by Ye and Zhao (1994) and Zhang (1980). There were two cold stages during the “ Little Ice Age ” in the studied period, one was 1650s – 1700s and the other was 1790s – 1900s (Fig. 2). The annual average temperatures for the two cold periods were 0.55 °C and 0.58 °C lower than that in 1900 – 1979 AD. Since the end of the “ Little Ice Age ” , the temperature increased rapidly and plentiful precipitation occurred in 1900 – 1920s (Fig. 9) (Gong et al., 2001). The sediment cores (TB-03) about 80 cm long were taken at the deeper area of Taibai Lake with a piston corer in 2003 (Fig. 1). The core sediments were sub- sampled at a 0.5 cm resolution for 0 – 50 cm and 1 cm resolution for 50 – 80 cm. The sub-samples were sealed in plastic bags to be transported to laboratory. The frozen dried samples were used for Pb dating, TOC, TN, and metal element analysis. The wet samples were used for grain size and pollen analysis. The main methods used were as ...

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... The change in the function of the lake to intensive fishing and aquaculture resulted from the adoption of modifications to the social system. [28] 2000-present: Widespread adoption of flush toilets that are unconnected with local piped sewage systems and a lack of new treatment plants have added to the increase in nutrient loading [29] 1987-present: Fish farm owners introduced economic domestic fishes into the lake, and the aquaculture intensity upgraded to a high level, resulting in exponential growth in aquaculture products [30] 1983-1993: High sedimentation flux correlated to soil loss due to intensive cultivation development [29,31] 1978-2013: In the lake catchment, the population increased and human settlements expanded, while farmland and lake area shrank (Supplementary Material 1.1) [32] 1976-present: Tongsipai Floodgate cut the dispersal route for juvenile fishes [30] The 1950s-1980s ...
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... The 1950s-1978: Rapidly developing local industrialization, mainly chemical fertilizer factories [29]. Thereafter, the lake received more nutrient loading from increasing domestic sewage, poorly treated industrial waste, and flushed chemical fertilizer [28] 1958-1970: High sedimentation flux correlated with the land reclamation around Taibai [29] 1955-1962: Damming construction: three reservoirs named Jingzhu, Kaotian, and Xianrenba were built in the upper reaches of Taibai. ...
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... Taibai investigation report 1987; 2 Huanggang Yearbooks 2010; 3 Land Use and Cover Change (LUCC)analyses of satellite images of Taibai catchment(Figure 3-2); 4(Jian, 2001); 5(Liu et al, 2007); 6(Gui et al, 2018). ...
Thesis
Environmental problems caused by lake eutrophication have become more widespread at a global level, threatening the safety of water, food and other daily needs of people living in the vicinity of lakes. Although lake types, physical conditions and causes of degradation vary from region to region, all threatened lake ecosystems face the same problem of identifying the mechanisms that underlie the deterioration of water quality or cause algal blooms in lakes, and discovering pathways to recovery is becoming an increasingly urgent matter. Theoretical and mathematical models based on Alternative Stable States (ASS) can be used to model and explain the deterioration and restoration of shallow lakes, while multiple patterns of ecosystem state response to external drivers have been validated by a large number of observations in European and North American lakes. In eastern China, eutrophic lakes account for 86.7% and heavily eutrophic lakes for 12.2% of more than 100 lakes in the Middle and Lower Reaches of the Yangtze River plain. Large lakes, such as Chaohu and Taihu, have experienced large cyanobacterial outbreaks in the early twenty-first century, and these disasters will probably be replicated in other lakes under similar conditions. I therefore need to understand the mechanism underlying such catastrophic shifts in lake ecosystems. Natural and anthropogenic influences on the ecological trajectories of lake ecosystems, response mechanisms, and how to avoid subsequent catastrophes are the main questions addressed by this thesis. To discover the external conditions that predominantly affect lake ecosystems in the lower Yangtse River, I used palaeolimnological tools and selected a typical lake in the middle and lower reaches of the Yangtze River, Lake Taibai, for a case study. The study used information relating to the species composition of subfossil diatom genera as indicators of the reconstructed ecosystem state as well as lake area, depth, chlorophyll content, transparency, ion concentration and nitrogen and phosphorus content as environmental factors to analyse the correlation between environmental changes. In terms of anthropogenic impacts, historical data on lake hydrodynamics, fish farming and nutrient loading in the basin over past decades were recovered using historical records, literature research and proxy reconstruction to calculate the magnitude of the correlation between ecosystem state driven by human and natural factors and to analyse possible responses by examining feedback mechanisms. Since it is difficult to use palaeoecological data alone to reveal the dynamic ecosystem changes and emergent mechanisms under the influence of various external factors, I developed an agent-based model (ABM) to simulate the influence of environmental and human activities on lake ecosystems to help analyse how past patterns of shifts in state occurred, the influence of external conditions on these changes and how to avoid the development of catastrophic ecosystem failures. The ABM was constructed on the basis of the predation-prey relationship and other interactions like competition and providing refuge and on known ecological theories to simulate population dynamics in aquatic food webs in response to external drivers. The developed ABM – LAKEOBS_MIX achieves a reasonable balance between generality and realism, providing insights of how ecosystems were affected by various drivers in MLYB-like lakes. The effects of the external environment are implemented as sub-models to the biotic interactions, and the currently available factor models are lake nutrient levels, temperature, water depth, area and changes in the number of fishes in the lake. In-silico experiments were designed with multiple factors to simulate different conditions and measure ecosystem response patterns. The simulations show that the patterns of equilibria developed from the same initial state can be very different due to stochasticity of spatial distribution and decision making of individuals in functional groups. Decades are needed for the modelled ecosystem to form a dynamic equilibrium without external disturbance, which can be altered by any sudden extinction of a functional group. In experiments where nutrient loading constantly impacts on the formed equilibrium, results show regime shifts that occurred in different time and patterns due to changes in the amount, adding pace and timing of nutrient load, the presence of other influencing factors. Besides, recovery pathways are simulated in hyper-eutrophic system state, confirming moderate natural fishing and nutrient removing are efficient approaches to lower the total nutrient level in lake ecosystems. Combining these two approaches provided us with an improved understanding of the development trajectory of lake ecosystems in the MLYB over the last 100 years. I discovered links between changes in conditions and their corresponding response mechanisms, and according to the results of simulations I was able to develop possible regulatory approaches to avoid abrupt system degradation
... Paleolimnological multi-proxy methods are helpful to obtain information on the ecological environment from sediments to reconstruct the original characteristics of lake ecology that could not be monitored before the development of these methods. Previous studies have investigated the nutrient evolution and drainage-basin erosion Liu et al. 2007;Xue and Yao 2011) of lakes in the Yangtze River Basin. However, some prior studies of Dianchi Lake (Fang et al. 2014;Tanaka et al. 2013;Wan et al. 2011) neglected to consider the environmental changes of small basins in the Dianchi watershed and their effects on the lake. ...
... Intense rainstorms can lead to severe soil erosion and extremely high sediment yields. Therefore, besides human factors, heavy rainfall can also contribute to high SAR in lakes (Liu et al. 2007). However, in this study, the correlation between SAR and rainfall was not significant (Fig. 7), indicating that precipitation was probably not a key factor affecting nutrient flux changes. ...
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In the last few decades, the eutrophication of lakes has been a serious issue in the middle and lower reaches of the Yangtze River watershed. To explore the relationship between lake systems and anthropogenic activities, sediments were collected from the Shuanglong reservoir in the Dianchi watershed in Southwest China. Total nitrogen (TN), total phosphorus (TP), total organic carbon (TOC), and the carbon isotopic ratio (δ¹³C) were analyzed in sediment cores to reconstruct the effects of natural succession and human activities on the past lacustrine environmental conditions. A reliable chronology of the sediment core was established by using the ²¹⁰Pb dating technique, which indicated that the age span of the 70-cm sediment core is from the years 1871 to 2011. Above – 31 cm depth in the core, TN, TP, TOC, C/N, and δ¹³C increased significantly, indicating that eutrophication has occurred since the 1980s. By combining the indicators of δ¹³C and C/N, it was shown that terrestrial and lacustrine components were the main sources of organic matter (OM) in the reservoir, which was mostly controlled by terrestrial C3 plants and algae. Since the 1980s, increased sewage discharge, fish aquaculture, fertilizer application, population, and economic strength have sped up the eutrophication process, and the eutrophication was further intensified in 2001. Graphical abstract
... Algal blooms are one of the most serious ecological and environmental problems affecting water bodies, and they can have a major impact on both human and ecosystem health. Taihu Lake, which is the study area of this paper, is located in the lower reaches of the Yangtze River Basin in China, which is an area with the most developed economy and densest population [1]. Taihu Lake is a typical large-scale shallow lake with various functions, including flood control, water supply, shipping, and aquaculture. ...
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The algal blooms caused by the eutrophication of lakes is a major environmental problem. In this study, we took China’s Taihu Lake as the research area, using multi-source satellite imagery data to monitor the information of algal blooms from 2008 to 2017. Following the analyses of the temporal and spatial variation trends of the blooms, water quality and meteorological data from land observation stations were employed to investigate the main environmental driving forces of the algal bloom outbreaks. The results show that, over the decade, the blooms with medium and higher hazard degrees mainly occurred in summer and autumn, and especially in autumn. From 2008 to 2016, the algal blooms outbreak degree was relatively stable, but, in 2017, it was severe, and the Northwest Lake area and the northern bays had heavier blooms than the other lake areas. From the analyses of the environmental driving forces, the variation trend of total nitrogen (TN) and total phosphorus (TP) concentrations in Taihu Lake from 2008 to 2017 was moderate, and the minimum concentrations of TN and TP both exceeded the threshold for algal bloom outbreaks. It was also found that the algal bloom area had notable correlations with the sunshine duration, wind speed and direction, precipitation, and air pressure. The research results of this paper will provide a theoretical basis for the scientific prediction of the occurrence of algal blooms in Taihu Lake.
... For instance, Jia et al. (2017) found that soil moisture severely declined under artificial afforestation in the Loess Plateau, which limited tree growth and even induced the degeneration of vegetation. Moreover, Liu et al. (2007) found that a change in the cultivation production patterns within the catchment was a dominant reason influencing catchment soil erosion and lake sediment influx in Taibai Lake, located in the middle reach of Yangtze River, China. Therefore, in our study catchment, we do not suggest returning farmland to tea plantation as our results indicate the high rates of soil loss can occur in locations such as old tea gardens (Fig. 10). ...
... The lake is small and shallow, with a surface area of approximately 28.98 km 2 , a mean depth of 3.2 m and catchment area exceeding 900 km 2 (Zhang et al., 2012). The lake now has no direct connection with Yangtze River, and is charged mainly by precipitation and input from rivers which flow into the lake from north and drain it to the southeast into Lake Longgan (Liu et al., 2007). The study area is subject to a subtropical monsoon climate, with an average annual temperature of 16.7 C, average annual precipitation of 1273 mm and average evaporation of 1041 mm (Xiao et al., 2012). ...
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The rapid development and exploitation of the Yangtze River basin in order to ensure human food security and increase living space in recent decades has resulted in significant potential for degradation of water quality in the river and in hundreds of lakes. Understanding how lake environments have evolved to their present state under a variety of external influences is crucial for evaluating their current status and anticipating future scenarios of environmental changes. However, the lakes along the middle reaches of the Yangtze River (MRY) are as yet little studied. Here, we described the long-term anthropogenic environmental transformations of a small lake (Lake Taibai) in the MRY area, based on a detailed quantitative geochemical analysis of the aliphatic hydrocarbons, nutrients (N and P), biogenic silica (BSi), and major and trace elements present in a dated sediment core retrieved from the lake. Our data revealed that levels of short-chain n-alkanes, αβ-hopanes and the trace elements arsenic (As) and cadmium (Cd) were all low for the entire record in sediments prior to ca. 1970, reflecting unpolluted natural state of the lake. Pronounced anthropogenic effects began to appear in sediments deposited in the subsequent years ca. 1970-1990, during which the levels of all these components were elevated, most likely driven by input of nitrogen (N) and phosphorus (P) containing chemical fertilizers, pesticides and diesel oil respectively. Since ca. 1990, changes of short-chain n-alkane levels in the sediment suggested the lake had undergone dramatic eutrophication in which existing anthropogenic stressors were exacerbated by technological advances that extended the use of chemical fertilizer into aquaculture. This pattern contrasted with an otherwise comparable lake in the lower Yangtze River basin, Lake Changdang, in which trace element and petroleum pollution were much more prominent due to dramatic urbanization and industrialization of the catchment.
... Sediment accumulation rate (SAR), is a fundamental parameter of lacustrine sedimentary processes, affecting lake morphology, stratification, nutrient dynamics and assemblages of aquatic flora and fauna (Rose et al., 2011;Zhang et al., 2013). Previous studies often relate the changes of SAR to soil erosion in the catchment, especially land use and land cover changes caused by human activity ( Liu et al., 2007;Rose et al., 2011;Xue and Yao, 2011;Xu et al., 2017). However, less focus has been directed towards the influence of atmospheric dust and precipitation of autogenetic carbonates (Neff et al., 2008;Yu et al., 2015). ...
... Heavy rainfall would enhance soil erosion over the lake catchment in arid region and increase the transport capacity of surface runoff ( Liu et al., 2007). However, vegetation cover is also sensitive to precipitation in the arid/semi-arid environments, where wetter climatic conditions correspond to denser vegetation cover . ...
... In addition to environmental change, deforestation and expanded agricultural land use associated with human activities may also accelerate soil erosion in the catchment, resulting in reduced protective capacity of land cover for soils ( Liu et al., 2007;Xu et al., 2017). The peak of the fluvial-Ti flux between 1930s and 1950s was mainly due to the agricultural development in the catchment. ...
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Lacustrine ecosystems are directly influenced by terrestrial soil erosion, and excessive sediment loading constitutes a significant and widespread environmental issue. In order to investigate the response of catchment soil erosion and organic carbon burial to climate change and human activity, a sediment core spanning the last 160 years was retrieved from Lake Chenghai in southwest China. Multi-proxy analysis including grain-size composition and geochemical indicators were undertaken in this study. The result of grain-size vs standard deviation method shows that the sensitive component with a modal size of 13.2 μm is related to fluvial processes and sensitive to the catchment soil erosion. The increasing intensity of soil erosion was mainly determined by the weakening of Indian summer monsoon and global warming, as well as intensive human activities during the middle of 20th century, which resulted in decreasing vegetation cover in Lake Chenghai catchment. The organic carbon burial rate was also attributed to the catchment disturbance, indicating that increased catchment soil erosion may impact the terrestrial carbon recycling.
... Previous sediment OM analyses have mostly relied on wellestablished gross geochemical proxies such as total organic carbon (TOC), total nitrogen (TN) and TOC/TN ratios and on stable isotope parameters (d 13 C and d 15 N) (Routh et al., 2004;Das et al., 2008;Dunnington et al., 2016). However, these signatures only give a broad description of sources (Liu et al., 2007). In contrast, the source specificity of lipid biomarkers can provide detailed information about the origins of sediment OM (Hu et al., 2009;Lu and Meyers, 2009;Choudhary et al., 2013;. ...
Article
Aliphatic hydrocarbon biomarkers from the surface sediments of lakes along the lower reaches of the Yangtze River (Eastern China) were analyzed in order to determine the origin and composition of organic matter (OM) in the sediment, which is necessary to understand how anthropogenic environmental change in the region is impacting on OM dynamics and carbon cycles. The results indicate that OM in lake sediments is derived from biogenic sources including phytoplankton, aquatic macrophytes, bacteria and terrestrial plants, and abiotic sources of petroleum hydrocarbon contamination. The significance of each source varies greatly between lakes. Inputs of autochthonous OM to sediments were closely dependent on nutrient levels and the organisms present in the lake water column. Cyanobacterial OM input, signified by the distribution of short-chain n-alkanes, was most abundant in sediments from the most severely polluted lake, West Lake Chaohu. OM derived from diatoms, indicated by C25 highly branched isoprenoids (HBIs), was relatively abundant in sediments from lakes Gucheng and Shijiu, the two studied lakes with the lowest nutrient levels. Growth of macrophytes in lakes Gucheng, Shijiu, Gehu and Yangcheng resulted in a significant accumulation of OM from these organisms in the sediments. In contrast, the input of allochthonous OM was controlled mainly by natural and anthropogenic activities around the lakes. For example, terrestrial plant OM input, deduced from the abundance and proportion of long-chain n-alkanes, was exceptionally high in the sediment of Lake Nanyi, perhaps stemmed from frequent severe flooding in the catchment. Input of fossil fuel OM reflected direct petroleum contamination of the water or the anthropogenic petroleum burning in the catchment. In addition, the allochthonous refractory OM tends to be enriched in sediments of lakes with strong hydrodynamic process. The results of this study provided a lot of details in explaining the variation of terrestrial OM dynamics and carbon cycle in response to anthropogenic activities.
... Metal elements (Al, Fe, Li, K, Mg, Cr, Cu, Zn, Sr) and total phosphorus (TP) were analysed using an inductively coupled plasma-atomic emission spectrometry (ICP-AES) after digesting sediments in a mixture of HF, HCl, HNO 3 and HClO 4 (3:0.5:6:0.5). After being weighed out (ca. 0.125 g), samples were transferred into a Teflon beaker for acid digestion and dilution before analysis (see details in Liu et al., 2007). Reference materials (GSD-9, GSD-11) were supplied by the Chinese Academy of Geological Sciences. ...
Article
Large river-floodplain systems which provide a variety of societal, economic and biological benefits are undergoing extensive and intensive human disturbance. However, floodplain lakes responses to multiple stressors are poorly understood. The Yangtze River and its floodplain which provide water and food resources for more than 300 million people are an important region in China. Hydrological regulation as well as socio-economic development have brought profound negative influence on this ecologically important area. To improve understanding of decadal-scale responses of floodplain lakes to multiple stressors, lake sediment proxies including particle size, geochemical elements, diatoms and chironomids were analysed in a lead-210 dated core from Futou Lake. The analyses show that dams constructed in 1935 and the early 1970s stabilized hydrological conditions in Futou Lake and impeded the interaction with the Yangtze River, resulting in a decrease in major elements (e.g., Mg, Al, Fe) transported into the lake and an increase of macrophyte-related chironomids (C. sylvestris-type, P. penicillatus-type and Paratanytarsus sp.). After the late 1990s, further decreases in major elements and increases in median grain size are attributed to the erosion of the Yangtze riverbed and declining supply of major elements-enriched sediments from the upper Yangtze caused by the impoundment of the Three Gorges Dam. Chironomid and diatom assemblages indicate that hydrological stabilization caused by dam constructions stimulated the growth of macrophytes, which may be important in buffering against an ecosystem state change towards a phytoplankton-dominated and turbid state with ongoing eutrophication. However, a recent increase in Zn, TP and the emergence of eutrophic diatom and chironomid species indicate initial signs of water quality deterioration which may be related to the combined effects of hydrological stabilization and aquaculture. Over all, the sediment record from Futou Lake emphasizes the importance of interactions between hydrological change and pollutant loads in determining floodplain lake ecosystem state.