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1.
锦州湾及附近河口沉积物中砷含量、分布及形态   总被引:5,自引:0,他引:5  
对葫芦岛3条河流和锦州湾水体、沉积物中As的含量、分布和形态进行了研究。结果表明:葫芦岛的连山河和五里河未受到明显的As污染,沉积物总As含量低于10 mg·kg-1,河水As含量低于10 μg·L-1,茨山河下游紧邻葫芦岛锌厂,受到了一定程度的As污染,沉积物As含量达75.2 mg·kg-1;五里河口区As污染非常严重,锌厂在该区排污口处沉积物As含量高达3176.1 mg·kg-1,超过国家沉积物As标准158倍;受锌厂排污的影响,锦州湾As污染也很严重,沉积物中As最高含量达到569.5 mg·kg-1,沉积物和孔隙水含量在剖面上具有相似的变化趋势,表明孔隙水As含量主要受沉积物As含量影响;锦州湾沉积物中As主要以可交换态存在,残渣态次之,盐酸提取态最少,表明锦州湾沉积物中As的活性很强,有大量的可交换态As随时会进入上覆水体,是重要的As释放源,而铁对As行为的影响占次要地位;沉积物中大量As的释放可能会对葫芦岛和锦州湾地区生态系统造成严重的威胁。  相似文献   
2.
城市化对杭州市鸟类营巢集团的影响   总被引:5,自引:0,他引:5  
为了了解城市化对鸟类营巢集团的影响,2007年3月至2007年8月,沿城市化梯度在杭州地区的城区、城乡结合区、农田区、农林交错区和自然林区等类型栖息地内设置3 000 m长、100 m宽的样线各18条,共计90条;并对其鸟类物种与群落营巢集团进行调查。调查共记录到繁殖鸟类96种,根据鸟类营巢位置可将其分为林冠枝干营巢集团、灌草丛营巢集团、林冠枝干/灌草丛营巢集团、自然洞穴营巢集团、人工建筑营巢集团、自然洞穴/人工建筑营巢集团地面营巢集团、水面营巢集团和寄生集团共9种。进一步分析显示,随城市化程度提高,鸟类营巢集团的数目呈整体下降趋势,而各集团的物种数也基本呈下降趋势。但是,不同的营巢集团对城市化的反应存在差异,导致其物种组成在群落中比例的明显变化。城市化程度的提高使树冠筑巢鸟、灌丛筑巢鸟、地面筑巢鸟及自然洞穴筑巢鸟在群落中所占的比例明显下降,其中地面筑巢鸟最为敏感,灌丛筑巢鸟次之。同时,自然洞穴/人工建筑集团的鸟类在群落中的比例却随着城市化程度的提高明显上升。各营巢集团之所以对城市化做出不同反应,是因为它们对筑巢地资源利用方式不同。此外,还发现植被盖度、人工设施面积、至市中心距离以及人为干扰等因素均可对鸟类营巢集团结构产生影响,但不同类型的营巢集团对上述因素的反应各异。  相似文献   
3.
To clarify the effects of forest fragmentation and a change in tree species composition following urbanization on endophytic fungal communities, we isolated fungal endophytes from the foliage of nine tree species in suburban (Kashiwa City, Chiba) and rural (Mt. Wagakuni, Ibaraki; Mt. Takao, Tokyo) forests and compared the fungal communities between sites and host tree species. Host specificity was evaluated using the index of host specificity (Si), and the number of isolated species, total isolation frequency, and the diversity index were calculated. From just one to several host-specific species were recognized in all host tree species at all sites. The total isolation frequency of all fungal species on Quercus myrsinaefolia, Quercus serrata, and Chamaecyparis obtusa and the total isolation frequency of host-specific species on Q. myrsinaefolia, Q. serrata, and Eurya japonica were significantly lower in Kashiwa than in the rural forests. The similarity indices (nonmetric multidimensional scaling (NMS) and CMH) of endophytic communities among different tree species were higher in Kashiwa, as many tree species shared the same fungal species in the suburban forest. Endophytic fungi with a broad host range were grouped into four clusters suggesting their preference for conifer/broadleaves and evergreen/deciduous trees. Forest fragmentation and isolation by urbanization have been shown to cause the decline of host-specific fungal species and a decrease in β diversity of endophytic communities, i.e., endophytic communities associated with tree leaves in suburban forests were found to be depauperate.  相似文献   
4.
Urban development is a major cause of habitat loss and fragmentation. Few studies, however, have dealt with fragmentation in an urban landscape. In this paper, we examine the genetic structure of isolated populations of the eastern red-backed salamander (Plethodon cinereus) in a metropolitan area. We sampled four populations located on a mountain in the heart of Montréal (Québec, Canada), which presents a mosaic of forested patches isolated by roads, graveyards and buildings. We assessed the genetic structure of these populations using microsatellite loci and compared it to the genetic structure of four populations located in a continuous habitat in southern Québec. Our results indicate that allelic richness and heterozygosity are lower in the urban populations. Exact differentiation tests and pairwise F ST also show that the populations found in the fragmented habitat are genetically differentiated, whereas populations located in the continuous habitat are genetically homogeneous. These results raise conservation concerns for these populations as well as for rare or threatened species inhabiting urban landscapes.  相似文献   
5.
We have investigated how indices of beach health perform in predicting the abundances of the crustaceans Emerita brasiliensis and Atlantorchestoidea brasiliensis from 22 metropolitan beaches in the cities of Rio de Janeiro and Niterói. Urbanization, Recreation and Conservation indices were used to assess sandy beaches health. Grain size and beach slope were used as morphodynamics indicators. Diagram from the principal component analysis clearly separated beaches with different urbanization and conservation levels. Generalized additive models (GAM's) were adjusted for species abundance using the indices and morphodynamic parameters as explanatory variables. Lower abundances were predicted for beaches with high levels of urbanization, whereas predictions of higher abundances occurred on beaches with high conservation levels. Using theoretic inference we showed that the urbanization index was the most important predictor for abundance of A. brasiliensis and the conservation index was the most important predictor for E. brasiliensis, reflecting different responses by upper tidal and intertidal species. A. brasiliensis occupies the intermediate and upper beach zones and E. brasiliensis is a swash zone filter-feeder that is more abundant in pristine beaches. Both species are highly subject to the impact of bathers and coastal modification. Unexpected, the recreation index did not show a negative effect on abundance predictions. Urbanization and conservation indices can be suitable metrics to measure anthropogenic effects on macrobenthic species. Moreover, mole crabs and sandhoppers species can be easily monitored. Coastal urbanization is a global phenomenon and we used the diagram of urbanization and conservation levels to expose possible directions for management strategies of metropolitan sandy beaches.  相似文献   
6.
Health research has shown that overweight and obesity in children and adults are becoming significant public health problems in the developing world. Evidence suggests that this phenomenon is more marked in urban than rural areas and may be associated with modernization. However, the underlying reasons for this nutrition transition remain unclear. Dietary shifts, often in conjunction with income and time constraints in urban environments, may entail a greater reliance on more convenient sugar and fat-dense food. Also, the necessity of labor-intensive agricultural work to meet rural subsistence needs is supplanted in urban environments by sedentary work. This paper extends the application of human behavioral ecology theory into the realm of international development and policy by applying Kaplan’s embodied capital theory to explore differences in food habits and nutritional status of Indo-Fijian children within the context of urbanization. Urban high-embodied-capital women demonstrate higher rates of wage-earning employment than urban low-embodied-capital or rural women. Findings indicate that urban high-embodied-capital households spend significantly more on food purchases, purchase a greater proportion of processed foods, and have children with higher body mass indexes (BMI) than do urban low-embodied-capital or rural households. This suggests that urban high-embodied-capital mothers, who tend to be employed, may be making trade-offs between income and food choices.
Dawn B. NeillEmail:
  相似文献   
7.
The modern trend in traditional medicines reflects an increase in the sale of complex herbal mixtures rather than those prepared from single plants. This trend is well documented in Traditional Chinese Medicine (TCM) and can be seen in recent developments in African traditional medicine. An increase in the prevalence of locally produced herbal preparations, especially those containing complex mixtures of several medicinal plants, sold in numerous retail outlets, including supermarkets and pharmacies has been observed. The appearance of these preparations is not surprising in rapidly urbanizing societies where traditional products are still desired but the users have neither the time nor resources to produce them. The production of these herbal mixtures has resulted in a growing herbal industry with about 50 to 100 private entrepreneurs in the informal market and has also contributed to creation of numerous jobs. The products are extensively advertised in newspapers, on the internet, television and radio programmes as well as through pamphlets and posters. This review examines and documents the prevalence of commercial herbal mixtures and preparations common in Pietermaritzburg, KwaZulu-Natal. Different types of herbal mixtures, claims, ethical and legal implications are discussed. Methods of preparation and marketing strategies as well as the way forward in ensuring economic impact, safety and efficacy of this new aspect of South African traditional medicine are also highlighted.  相似文献   
8.
The goal of the present study was to investigate the influence of urbanization on the richness, abundance and composition of arthropod communities associated with creosote bush, Larrea tridentata [DC] Cov., in Phoenix, Arizona. Arthropod communities were sampled in two desert types varying in degree of urbanization including fringe deserts (relatively undisturbed expanses of desert outside of Phoenix) and urban deserts (patches of desert within the urban core of Phoenix). Two studies were conducted including (1) a seasonal study (conducted at two fringe desert and two urban desert sites over a nine-month period), and (2) a snapshot study (conducted at multiple fringe desert and urban desert sites over an eight-day period). Results from both studies demonstrated that overall richness and abundance of creosote bush arthropod communities were lower in urban deserts than in fringe deserts. Additionally, creosote bush arthropod community composition varied greatly, both temporally and spatially. These differences in richness and abundance between fringe deserts and urban deserts suggest that the creosote bush arthropod community may be a useful focal biotic community to monitor when assaying for environmental change due to urbanization in arid habitats.  相似文献   
9.
“城-郊-乡”森林生态样带植被变化梯度分析   总被引:7,自引:0,他引:7       下载免费PDF全文
沿纽约市“市区-郊区-农区”140km森林生态样带,对9个样地19个样方的森林植被进行了研究。植被组成和结构沿样带变化明显,分异出城区森林、郊区森林和农区森林等不同类型,优势种替代明显,植物种类也形成了不同的生态类型。植被的梯度变化与人类活动密切相关,城市化对植被有重要影响。森林生态样带是研究人类活动对植被影响的好手段。  相似文献   
10.
As a key issue in China’s urban development, urbanization creates increasing pressure on the environment. Thus, a better understanding of the relationship between urbanization and the eco-environment is necessary for Chinese policy makers to realize sustainable urbanization development. Making reference to physical coupling models, we developed a coupling coordination degree model in order to examine the relationship between urbanization and the eco-environment in Shanghai, using data from 1980 to 2013. The comprehensive level of Shanghai’s urbanization process during the study period was estimated using an index composed of four primary indicators, namely: demographic urbanization, spatial urbanization, social urbanization, and economic urbanization. We also developed an index system for the eco-environment, which was based on four primary indicators: the environmental level, eco-environmental endowment, eco-environmental pressure and eco-environment response. The entropy method was subsequently employed in order to identify the contribution made by each indicator to the compound system during the study period. The results show that: (1) economic urbanization and eco-environmental response made the greatest contributions to the urbanization subsystem and the eco-environmental subsystem, respectively—these are thus the key factors to consider in policy decisions aiming to adjust the coupling coordination degree between the two subsystems; (2) the two parameters α-urbanization and β-eco-environment were found to have minimal effect on the coupling coordination system; (3) the coupling coordination between urbanization and the eco-environment produced an S-shaped curve, and both subsystems were found to have evolved from seriously unbalanced development at the start of the study period into superiorly balanced development at the close of the study period. The results of this study hold important implications for efforts to achieve the coordinated development of both urbanization and the eco-environment.  相似文献   
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