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  • SAGE Publications  (5)
  • Geography  (5)
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  • Geography  (5)
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  • 1
    Online Resource
    Online Resource
    Impacts of human activity on the late-Holocene development of the subaqueous Yangtze delta, China, as shown by magnetic properties and sediment accumulation rates
    SAGE Publications ; 2011
    In:  The Holocene Vol. 21, No. 3 ( 2011-05), p. 393-407
    Details
    In: The Holocene, SAGE Publications, Vol. 21, No. 3 ( 2011-05), p. 393-407
    Abstract: Development of the Yangtze delta during the late Holocene, and its relationship to human activities in the drainage basin, was analyzed using data from 16 cores collected from distributaries to the prodelta. We used AMS 14 C dating and digital elevation model (DEM) data from marine charts from 1864 through 2005 to determine ages and estimate sediment accumulation rates. The results demonstrate that the latest major subaqueous delta front formed within the past c. 0.8 cal. ka and features remarkably high accumulation rates (1—4 cm/yr) in comparison with those of previous delta fronts. We also examined the temporal distribution of grain size and magnetic susceptibility in all 16 cores. Results show soil-derived superparamagnetic (SP) minerals generally occur, and even dominate, in the recent ( c. 1.7 cal. ka) Yangtze delta fine-grained sediment, as shown by high values of frequency-dependent magnetic susceptibility (both χ FD and χ FD %). Rock-derived magnetite dominates generally in the river channel and delta front sand bodies as a result of hydrodynamic sorting, but is also enriched in both fine and coarse-grained sediment formed more recently ( c. 0.8 cal. ka), as evidenced by rising values of mass specific magnetic susceptibility (χ LF ). SP grains were deposited as early as the late Neolithic, possibly indicating local deforestation associated with the use of fire at that time. We suggest major deforestation in the drainage basin started c. 1.7 cal. ka BP, and intensified after c. 0.8 cal. ka BP when both χ LF and χ FD show the highest values. We therefore conclude that upland deforestation and cultivation as a result of the migration of human populations from northern China since c. 1.7 cal. ka BP resulted in increased sediment discharge of the Yangtze and played an important role in recent delta construction.
    Type of Medium: Online Resource
    ISSN: 0959-6836 , 1477-0911
    URL: Article
    DOI: 10.1177/0959683610378885
    RVK:
    RA 1000
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2011
    detail.hit.zdb_id: 2027956-5
    SSG: 14
    SSG: 3,4
    Location Call Number Limitation Availability
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    Online Resource
  • 2
    Online Resource
    Online Resource
    The spatiotemporal heterogeneity of the relationship between PM 2.5 concentrations and the surface urban heat island effect in Beijing, China
    SAGE Publications ; 2022
    In:  Progress in Physical Geography: Earth and Environment Vol. 46, No. 1 ( 2022-02), p. 84-104
    Details
    In: Progress in Physical Geography: Earth and Environment, SAGE Publications, Vol. 46, No. 1 ( 2022-02), p. 84-104
    Abstract: Air pollution and the urban heat island (UHI) effect are two serious problems in many cities and have become increasingly serious with accelerated urbanization. The relationship between fine particulate matter (PM 2.5 ) and the UHI effect has become a research topic of major interest to help avoid the vicious cycle of the UHI effect and air pollution, but recent studies still focus on correlation analysis, lacking attention to the spatiotemporal heterogeneity of their relationship. Combining remote sensing and in situ data, this study analyzed the spatiotemporal heterogeneity of the interaction between the UHI effect and PM 2.5 in Beijing over four seasons by using a coupling coordination degree model, and the characteristics of spatiotemporal heterogeneity were analyzed from both biophysical and socioeconomic aspects. The modified normalized difference water index (MNDWI) and normalized difference vegetation index (NDVI) were selected as the indices from a biophysical perspective. Urban functional areas derived from points of interest (POIs) were used to represent the area’s socioeconomic background. The results showed that the relationship between PM 2.5 and the UHI effect has spatiotemporal heterogeneity. The areas exhibiting high degrees of coupling coordination were most widely distributed in spring, and the highest degree of coupling coordination appeared in summer. The four seasons of high coupling coordination areas occurred over four seasons, covering more than 58.3% of Beijing’s area, mainly concentrated in business-related functional areas. Areas where the positive interaction between the UHI effect and air pollution was weak tended to have a higher proportion of vegetation. The results of this work are of theoretical and management value for mitigating the threat of rapid urbanization to human health.
    Type of Medium: Online Resource
    ISSN: 0309-1333 , 1477-0296
    URL: Article
    DOI: 10.1177/03091333211033209
    RVK:
    RA 1000
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
    detail.hit.zdb_id: 2006623-5
    SSG: 14
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    Online Resource
  • 3
    Online Resource
    Online Resource
    Environmental changes since 8.4 ka reflected in the lacustrine core sediments from Nam Co, central Tibetan Plateau, China
    SAGE Publications ; 2008
    In:  The Holocene Vol. 18, No. 5 ( 2008-08), p. 831-839
    Details
    In: The Holocene, SAGE Publications, Vol. 18, No. 5 ( 2008-08), p. 831-839
    Abstract: The Tibetan Plateau induces and enhances the Asian monsoon that influences the plateau itself, East China and even the whole of Asia. Pursuing the changing monsoon history and its impact in this environment-sensitive area is a key for understanding the climatic changes. Here, we present the initial results from core sediments in Nam Co, central Tibet, to elucidate the Holocene environment changes in this area. The studied lake (Nam Co) is the second largest lake, with an elevation of 4718 m, water area of 2015 km 2 and catchment area of 10 610 km 2 . By using echo-seismic profiling and hydro-echosounding, we investigated the bathymetric distribution of the whole lake. One 332 cm long PISTON core was successfully taken in the east part of the lake at 60 m water depth. Twelve AMS 14 C dates from top to bottom of this core established a good time sequence. TOC, TN, n-alkanes, grain size, clay minerals, Fe/Mn, Sr/Ba and CaCO 3 content were analysed with sampling intervals from 1 cm to 10 cm. Results showed that since 8400 yr BP, the environment changes in this region indicate three stages. The early stage (8400—6900 yr BP) was characterized by slight shifting from warm to cold with a cold-dry interval at 8100—7800 yr BP. The middle stage was from 6900 to 2900 yr BP, during which climate changed from warm-humid to cold-dry. However, around 2900 yr BP, the climate once was slightly cold but strongly dry. The late stage, from 2900 yr BP to present, was characterized by a general tendency toward cold-dry: the first temperature decline was around 1700—1500 yr BP, following which temperature increased once, before decreasing again around 600—300 yr BP, which might be the result of the `Little Ice Age'.
    Type of Medium: Online Resource
    ISSN: 0959-6836 , 1477-0911
    URL: Article
    DOI: 10.1177/0959683608091801
    RVK:
    RA 1000
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2008
    detail.hit.zdb_id: 2027956-5
    SSG: 14
    SSG: 3,4
    Location Call Number Limitation Availability
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    Online Resource
  • 4
    Online Resource
    Online Resource
    Late-Holocene fluctuations of monsoonal Qiangyong Glacier, southern Tibetan Plateau
    SAGE Publications ; 2021
    In:  The Holocene Vol. 31, No. 7 ( 2021-07), p. 1138-1147
    Details
    In: The Holocene, SAGE Publications, Vol. 31, No. 7 ( 2021-07), p. 1138-1147
    Abstract: Glaciers on the Tibetan Plateau (TP) are reliable water sources for Asia. Continuously high-resolution and high-accuracy long-term glacier fluctuations have been examined to improve the reliability of predictions regarding future TP glacier behavior under global climate change. In this study, we analyzed physiochemical parameters in typical glaciolacustrine sediments to reconstruct multidecadal activities of the monsoonal Qiangyong Glacier over the past ~2500 years. The results show that the glacier advanced most strongly during 560 BC–AD 100, followed by AD 1050–1850 and AD 600–850. It retreated most severely during AD 1850–present, followed by AD 100–600 and AD 850–1050. This continuous record corresponds well with changes in the temperature and regional precipitation before the Current Warm Period, exhibiting “warm-humid-retreat” and “cold-dry-advance” patterns. This indicates that temperature changes, rather than precipitation variations, control the monsoonal glaciers at the southern TP at multidecadal to centennial scales. As global warming continues, although the precipitation on the southern TP is projected to increase, the mass loss of TP monsoonal glaciers is expected to continue.
    Type of Medium: Online Resource
    ISSN: 0959-6836 , 1477-0911
    URL: Article
    DOI: 10.1177/09596836211003209
    RVK:
    RA 1000
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2021
    detail.hit.zdb_id: 2027956-5
    SSG: 14
    SSG: 3,4
    Location Call Number Limitation Availability
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    Online Resource
  • 5
    Online Resource
    Online Resource
    Climate and human induced 2000-year vegetation diversity change in Yunnan, southwestern China
    SAGE Publications ; 2022
    In:  The Holocene Vol. 32, No. 11 ( 2022-11), p. 1327-1339
    Details
    In: The Holocene, SAGE Publications, Vol. 32, No. 11 ( 2022-11), p. 1327-1339
    Abstract: Understanding long-term vegetation diversity patterns and their potential responses to climate and/or human driven processes are important for ecosystem modeling and conservation. Late-Holocene fossil pollen assemblage and associated vegetation diversity estimates provide an opportunity to explore the interactions among vegetation, climate, and human activities. A continuous 2000-year palynological record was obtained from the Beihai Wetland, southwestern China, to represent regional vegetation history, particularly the vegetation diversity changes. The results indicate that regional vegetation was dominated by deciduous broadleaved forest components (e.g. Alnus, deciduous Quercus), which showed a gradual decrease accompanied by expansion of herbaceous taxa (mainly Poaceae) after AD 800. Such progressive decline of forest was attributed to regional deforestation driven by intensified human activities, which was further confirmed by the increasing non-pollen polymorph abundance, particularly an abrupt rise after AD 1350. Vegetation diversity based on the Hill numbers ( N0, N1, and N2) showed a dramatic decline between ca. AD 200–400, which was triggered by regional fire events as shown by increased charcoal abundance from a nearby lake. The vegetation diversity reduced gradually after AD 800, especially the vegetation richness reflected by N0, revealing the transitional process from climate-driven to human-dominated vegetation changes. Minor increases of vegetation diversity occurred during Chinese dynastical transitions, probably due to reduced human activities following war-induced population crises. On the multidecadal scale, variations in vegetation diversity correlated significantly with climate fluctuations (revealed by synthesized temperature of China and stable oxygen isotope record from Dongge Cave) before AD 800, indicating a climate dominant condition. Then, the correlation between vegetation diversity and climate declined after AD 800, representing a progressive transition to human-dominant condition. In addition, the compositional turnover based on DCCA of the fossil pollen assemblage revealed a stepwise decrease, indicating reduced vegetation turnovers under anthropogenic influences.
    Type of Medium: Online Resource
    ISSN: 0959-6836 , 1477-0911
    URL: Article
    DOI: 10.1177/09596836211041730
    RVK:
    RA 1000
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2022
    detail.hit.zdb_id: 2027956-5
    SSG: 14
    SSG: 3,4
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Online Resource
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