Spatial distribution patterns of total mercury （THg） in 36 surficial sediment samples representing five regions of Lake Taihu were assessed using the ArcGis geostatistical analyst module. The pollution levels of THg...Spatial distribution patterns of total mercury （THg） in 36 surficial sediment samples representing five regions of Lake Taihu were assessed using the ArcGis geostatistical analyst module. The pollution levels of THg were also evaluated from the same five lake regions. Concentrations of THg were in a ranged of 23-168 ng/g （mean 55 ng/g） in surfical sediments, which was significantly higher than those established baseline levels of the lake. Results of THg indicated that the northern region exhibited notably higher values, the bay regions showed elevated values relative to open areas, and the lakeside regions were higher than those observed in the central area. Lake Taihu suffered moderate to high Hg pollution, and expressed clear Hg enrichment status according to monomial pollution index I geo and human activity factors. The concentrations of THg in the surficial sediments of Lake Taihu showed moderate-strong variation （coefficient of variation 52%）. Geostatistical analysis indicated a weak spatial self-correlation, suggesting the contamination of Hg in Lake Taihu is primarily the result of anthropogenic activities.展开更多
Abies georgei var.smithii is an important plant species in Southeast Tibet,China.It has high ecological value in terms of biodiversity protection,as well as soil and water conservation.We analyzed the spatial pattern ...Abies georgei var.smithii is an important plant species in Southeast Tibet,China.It has high ecological value in terms of biodiversity protection,as well as soil and water conservation.We analyzed the spatial pattern and associations of A.georgei var.smithii populations at different growth stages by using Ripley's L function for point pattern analysis.The diameter structure was a nearly reverse 'J' shape.The amount of saplings and medium-sized trees accounts for a large part of the entire population,suggesting a high regeneration rate and an expanding population.In the transition from saplings to medium trees or to large trees,saplings show a significant aggregation distribution at small scales,while medium trees and large trees show a random distribution.There are significant inverse associations between saplings and medium trees and large trees at small scales,while there are no obvious associations between medium trees and large trees.The natural regeneration was affected by interspecific competition,and it was also affected by intraspecific competition.The joint effects of biological characteristics and environmental factors contribute to the spatial distribution pattern and associations of this A.georgei var.sm ithii population.展开更多
This study was conducted on the spatial distribution characteristics of surface tidal currents in the southwestern Taiwan Strait based on the quasi-harmonic analysis of current data obtained by two high frequency surf...This study was conducted on the spatial distribution characteristics of surface tidal currents in the southwestern Taiwan Strait based on the quasi-harmonic analysis of current data obtained by two high frequency surface wave radar(HFSWR) systems. The analysis shows that the tidal current pattern in the southwestern Taiwan Strait is primarily semi-diurnal and influenced significantly by shallow water constituents. The spatial distribution of tidal current ellipses of M2 is probably affected by the interaction between two different systems of tide wave, one from the northern mouth of Taiwan Strait and the other from the Bashi Channel. The directions of the major axes of M2 tidal current ellipses coincide roughly with the axis of the Taiwan Strait. The spatial distribution of the magnitudes of the probable maximum current velocity(PMCS) shows gradual increase of the velocity from northeast to southwest, which is in accordance with the spatial distribution of the measured maximum current velocity(MMCS). The directions of the residual currents are in accordance with the direction of the prevailing monsoon wind at the Taiwan Strait and the direction of the Taiwan warm current during summer. The bathymetry also shows a significant effect on the spatial distribution characteristics of tidal currents.展开更多
To study the water quality influenced by the anthropogenic activities and its impact on the phytoplankton diversity in the surface waters of Miaodao Archipelago, the spatiotemporal variations in phytoplankton communit...To study the water quality influenced by the anthropogenic activities and its impact on the phytoplankton diversity in the surface waters of Miaodao Archipelago, the spatiotemporal variations in phytoplankton communities and the environmental properties of the surface waters surrounding the Five Southern Islands of Miaodao Archipelago were investigated, based on seasonal field survey conducted from November 2012 to August 2013. During the survey, a total of 109 phytoplankton species from 3 groups were identified in the southern waters of Miaodao Archipelago, of which 77 were diatoms, 29 were dinoflagellates, and 3 were chrysophytes. Species number was higher in winter（73）, moderate in autumn（70）, but lower in summer（31） and spring（27）. The species richness index in autumn（5.92） and winter（4.28） was higher than that in summer（2.83） and spring（1.41）.The Shannon-Wiener diversity index was high in autumn（2.82）, followed by winter（1.99） and summer（1.92）, and low in spring（0.07）. The species evenness index in autumn（0.46） and summer（0.39） was higher than that in winter（0.32） and spring（0.02）. On the basis of principal component analysis（PCA） and redundancy analysis（RDA）, we found that dissolved inorganic nitrogen（DIN） and chemical oxygen demand（COD） in spring, COD in summer, p H in autumn, and salinity and oil pollutant in winter, respectively, showed the strongest association with the distribution of phytoplankton diversity. The spatial heterogeneity of the southern waters of Miaodao Archipelago was quite obvious, and three zones, i.e., northeastern, southwestern and inter-island water area, were identified by cluster analysis（CA） based on key environmental variables.展开更多
基金supported by the National Natural Science Foundation of China (No.21077097)
文摘Spatial distribution patterns of total mercury （THg） in 36 surficial sediment samples representing five regions of Lake Taihu were assessed using the ArcGis geostatistical analyst module. The pollution levels of THg were also evaluated from the same five lake regions. Concentrations of THg were in a ranged of 23-168 ng/g （mean 55 ng/g） in surfical sediments, which was significantly higher than those established baseline levels of the lake. Results of THg indicated that the northern region exhibited notably higher values, the bay regions showed elevated values relative to open areas, and the lakeside regions were higher than those observed in the central area. Lake Taihu suffered moderate to high Hg pollution, and expressed clear Hg enrichment status according to monomial pollution index I geo and human activity factors. The concentrations of THg in the surficial sediments of Lake Taihu showed moderate-strong variation （coefficient of variation 52%）. Geostatistical analysis indicated a weak spatial self-correlation, suggesting the contamination of Hg in Lake Taihu is primarily the result of anthropogenic activities.
基金funded by the National Key Technology Support Program (2013BAC04B01)
文摘Abies georgei var.smithii is an important plant species in Southeast Tibet,China.It has high ecological value in terms of biodiversity protection,as well as soil and water conservation.We analyzed the spatial pattern and associations of A.georgei var.smithii populations at different growth stages by using Ripley's L function for point pattern analysis.The diameter structure was a nearly reverse 'J' shape.The amount of saplings and medium-sized trees accounts for a large part of the entire population,suggesting a high regeneration rate and an expanding population.In the transition from saplings to medium trees or to large trees,saplings show a significant aggregation distribution at small scales,while medium trees and large trees show a random distribution.There are significant inverse associations between saplings and medium trees and large trees at small scales,while there are no obvious associations between medium trees and large trees.The natural regeneration was affected by interspecific competition,and it was also affected by intraspecific competition.The joint effects of biological characteristics and environmental factors contribute to the spatial distribution pattern and associations of this A.georgei var.sm ithii population.
基金supported by the National High Technology Research and Development Program (‘863’ Program) of China under contract No. 2012AA091701the Fundamental Research Fund for the Central University of China under the contract No. 2012212020211
文摘This study was conducted on the spatial distribution characteristics of surface tidal currents in the southwestern Taiwan Strait based on the quasi-harmonic analysis of current data obtained by two high frequency surface wave radar(HFSWR) systems. The analysis shows that the tidal current pattern in the southwestern Taiwan Strait is primarily semi-diurnal and influenced significantly by shallow water constituents. The spatial distribution of tidal current ellipses of M2 is probably affected by the interaction between two different systems of tide wave, one from the northern mouth of Taiwan Strait and the other from the Bashi Channel. The directions of the major axes of M2 tidal current ellipses coincide roughly with the axis of the Taiwan Strait. The spatial distribution of the magnitudes of the probable maximum current velocity(PMCS) shows gradual increase of the velocity from northeast to southwest, which is in accordance with the spatial distribution of the measured maximum current velocity(MMCS). The directions of the residual currents are in accordance with the direction of the prevailing monsoon wind at the Taiwan Strait and the direction of the Taiwan warm current during summer. The bathymetry also shows a significant effect on the spatial distribution characteristics of tidal currents.
基金The Special Project of Science and Technology Fundamental Work from the Ministry of Science and Technology of China under contract No.2012FY112500the National Natural Science Foundation of China under contract Nos 41206111 and 41206112
文摘To study the water quality influenced by the anthropogenic activities and its impact on the phytoplankton diversity in the surface waters of Miaodao Archipelago, the spatiotemporal variations in phytoplankton communities and the environmental properties of the surface waters surrounding the Five Southern Islands of Miaodao Archipelago were investigated, based on seasonal field survey conducted from November 2012 to August 2013. During the survey, a total of 109 phytoplankton species from 3 groups were identified in the southern waters of Miaodao Archipelago, of which 77 were diatoms, 29 were dinoflagellates, and 3 were chrysophytes. Species number was higher in winter（73）, moderate in autumn（70）, but lower in summer（31） and spring（27）. The species richness index in autumn（5.92） and winter（4.28） was higher than that in summer（2.83） and spring（1.41）.The Shannon-Wiener diversity index was high in autumn（2.82）, followed by winter（1.99） and summer（1.92）, and low in spring（0.07）. The species evenness index in autumn（0.46） and summer（0.39） was higher than that in winter（0.32） and spring（0.02）. On the basis of principal component analysis（PCA） and redundancy analysis（RDA）, we found that dissolved inorganic nitrogen（DIN） and chemical oxygen demand（COD） in spring, COD in summer, p H in autumn, and salinity and oil pollutant in winter, respectively, showed the strongest association with the distribution of phytoplankton diversity. The spatial heterogeneity of the southern waters of Miaodao Archipelago was quite obvious, and three zones, i.e., northeastern, southwestern and inter-island water area, were identified by cluster analysis（CA） based on key environmental variables.
