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1.
Estuaries are environments where freshwater and seawater mix and they display various salinity profiles.The construction of river barrages and dams has rapidly changed these environments and has had a wide range of impacts on plankton communities.To understand the dynamics of such communities,researchers need accurate and rapid techniques for detecting plankton species.We evaluated the diversity of eukaryotic plankton over a salinity gradient by applying a metagenomics tool at the Nakdong River estuary in Korea.Environmental samples were collected on three dates during summer and autumn of 2011 at the Eulsukdo Bridge at the mouth of that river.Amplifying the 18 S rDNA allowed us to analyze 456 clones and 122 phylotypes.Metagenomic sequences revealed various taxonomic groups and cryptic genetic variations at the intra-and inter-specific levels.By analyzing the same station at each sampling date,we observed that the phylotypes presented a salinity-related pattern of diversity in assemblages.The variety of species within freshwater samples reflected the rapid environmental changes caused by freshwater inputs.Dinophyceae phylotypes accounted for the highest proportion of overall diversity in the seawater samples.Euryhaline diatoms and dinoflagellates were observed in the freshwater,brackish and seawater samples.The biological data for species composition demonstrate the transitional state between freshwater and seawater.Therefore,this metagenomics information can serve as a biological indicator for tracking changes in aquatic environments.  相似文献   

2.
For the Pinang River, originating in the western highlands of Penang Island, the nature, sources and extent of pollution were studied. The river water samples collected at five selected sites were analyzed for various physical and chemical parameters, namely temperature, DO, BOD, COD, SS, pH, ammoniac nitrogen (AN), and conductance. Long-term data of rainfall and temperature were analyzed to determine the seasonal variations of the streamflow.The streamflow during the dry season is extremely low compared to the wet season, thus concentrations of contaminants derived from point pollution source increase due to lack of rainfall and runoff events. On the contrary, in the predominantly urban and agricultural catchments, non-point pollution source increases during rainy season through seepage and runoff. Effects of seasonal variations consequently deterrnine the quantity and quality of the water parameters.The Jelutong River, the Dondang River and the Air Itam River carry the seepage from widely urban and residential areas to the main Pinang River systems. Water quality of the Pinang River at different points assessed by the water quality indices was compared. According to the quality indices during the study period, water quality in the upper reaches of the river is medium to good. It dwindled in the plains, due to the seepage from urban areas and discharges from the industrial and agricultural lands.  相似文献   

3.
Decreasing fish resources in estuaries is a subject of anthropogenic activities.Studies of the spatiotemporal distribution of fish eggs and larvae can help identify the status and processes underlying recruitment in a fishery.As the fifth largest river estuary in the world,the Huanghe(Yellow)River estuary(HRE)is a typical estuary that has been seriously affected by human activities.Annual surveys on ichthyoplankton and environmental factors were conducted in the months of May of 2005 and 2009-2016 in the HRE to investigate the spatiotemporal distribution of fish eggs and larvae and the associated influencing factors.A total of 23 and 20 species of eggs and larvae,respectively,were collected.The dominant orders were Perciformes(51.2%)and Clupeiformes(25.6%).The average number of fish species eggs and larvae were 6.0 and 4.1 in average abundance of 0.91 and 0.13 ind./m~3,respectively.The dominant species were mainly low-commercial-value small-sized fishes,such as Clupanodon punctatus,Hare,ngula zutnasi,and Acanthogobius,whereas certain traditional commercial fishes,such as Trichiurus lepturus,and Clupea pallasii,were not seen.Analysis of the fish egg and larval community revealed four temporal assemblages and two spatial assemblages.Salinity was the main factor on the spatial distribution of ichthyoplankton communities,the species number and Shannon-Weiner diversity index(H')of the fish egg and larval community near the river mouth with lower salinity were significantly lower than the community far away from the river mouth with higher salinity.In addition,increases of water temperature promoted the number and abundance of fish species eggs,and the areas of abundant prey tended to have a more diversified and abundant of ichthyoplankton species.In overall,overfishing,dam construction,and other human activities were the main drivers that led to the substantial decline in fishery resources in the HRE.  相似文献   

4.
Using social exchange theory, this study investigated residents’ attitudes toward the preliminary stage of tourism development in nature reserves in Wuyishan National Nature Reserve of China, and the socio-economic and negative effects of residents’ attitude toward the tourist industry. Results of the questionnaire survey indicated that local people perceived they could benefit from the economic activities related to tourism, and were supportive of the conservation of natural resources and local culture, sustainable community development, and community participation in ecotourism planning and management. This study also revealed that the variables of age, gender, education level, household income, family size, non-farm work arrangements, and the distance to tourism attractions, have significant association with respondents’ attitudes toward ecotourism development, or negative impacts of the tourist industry. Respondents who are male, or have a higher household income, are more supportive of tourism development inside the reserve. Younger and more highly educated community members are more likely to support learning more about natural and cultural resources and landscapes. Respondents who have a higher household income, or live far from the village center, are more concerned about the negative environmental impacts of tourism development.  相似文献   

5.
SWAT模型运行结构与组织研究   总被引：1，自引：0，他引：1  
SWAT(Soil and Water Assessment Tool)模型是美国农业部开发的具有物理基础的分布式非点源模型系统,可以模拟流域尺度的多种地理过程,如产水、产沙、养分和农药等的迁移与转化,并预测不同的管理措施对流域过程的影响。SWAT模型模拟内容多,程序结构复杂,导致集成应用和模型修改的困难。本文在模型结构剖析的基础上讨论了SWAT模型的内部运行结构,列举实例给出了运行控制文件的写法。  相似文献   

6.
资江是洞庭湖的第二大支流，其中上游锑(Sb)矿采矿冶炼工业发达，给资江下游及洞庭湖区带来了严重的重金属污染风险。以资江河口区为研究区，采集了132个农田土壤样品及7个资江水样，综合采用多种污染评价方法、空间分析、多元统计分析方法对研究区重金属进行了污染评价及来源分析。结果表明，研究区农田土壤重金属平均质量分数表现为Zn>Cr>Ni>Pb>Cu>As>Sb>Cd，旱田土壤重金属平均质量分数除Pb外均高于水田。Sb、As、Cd为主要污染元素，Sb达到了中等污染和中等生态风险的程度，总体处于轻微-中等生态风险程度。资江水体Sb质量浓度较高，平均为10.51 μg/L。Sb主要来源于中上游的锑矿工业，受高锑质量浓度地表水灌溉、垃圾填埋场以及燃煤等人为活动的控制；Cd主要来源于农药化肥、生活垃圾和城镇废水等人为活动；Cr主要来源于成土母质，而Cu、Zn、As、Ni、Pb受成土母质和人为活动的双重控制。   相似文献   

7.
Yan  Muting  Chen  Xiaofeng  Chu  Wei  Li  Weixin  Li  Minqian  Cai  Zeming  Gong  Han 《中国海洋湖沼学报》2023,41(1):215-228

The microbial communities colonized on microplastics (MPs) have attracted widespread attention. However, few studies focused on the MPs impacts on mangrove ecosystems, particularly on bacterial communities. We investigated the MPs pollution in mangrove of Zhujiang (Pearl) River estuary (ZRE). To study the potential risk posed by MPs to the mangrove ecosystems, the differences in bacterial communities, functions, and complexity between MPs and sediment samples were reported for the first time. Microplastics (2 991±1 586 items/kg dry weight (dw)) in sediment were mainly fibers and polyethylene, mostly transparent, and in size less than 0.5 mm. Bacterial communities and functions significantly differed from MPs in mangrove sediment. Compared with sediment, MPs significantly enriched members of Proteobacteria, Bacteroidetes, and Actinobacteria, as well as the bacteria associated with plastic-degrading and human diseases on their surface, suggesting that microbial communities on MPs may promote MPs degradation and the spread of diseases, posing potential risk to mangrove ecosystems and human health. Although bacteria on MPs exhibited a lower diversity, the co-occurrence network analysis indicated that network of bacteria colonized on MPs was bigger and more complex than those of mangrove sediment, illustrating that MPs can act as a distinct habitat in this special ecosystem. This study provides a new perspective for increasing our understanding of microplastic pollution in mangrove ecosystems.

  相似文献   

8.
To assess the recovery rate of meiofaunal and nematode communities upon abatement of sewage pollution, a field transplantation experiment was conducted in Tai Tam, which is a non-polluted, shallow subtidal habitat on the southern portion of Hong Kong Island. The sediments used were from one site located in Victoria Harbour that was heavily influenced by sewage pollution, and one site in the outside-harbor area, which was relatively clean. In addition, sediments from Tai Tam were used as a control. Fresh sediments with meiofauna were collected from the aforementioned sites, placed in plastic trays and transplanted to Tai Tam. Sediments were retrieved at the beginning of the experiment and at 1-, 3-, and 8-weeks after transplantation for analysis of the meiofaunal and nematode communities as well as the sediment characteristics. The results showed that the meiofaunal and nematode communities in the control sediments were consistent at the four sampling periods, while it took three and eight weeks, respectively, for the nematode communities from the outside-harbor and inside-harbor sites to become similar to the control. These findings indicated that the relatively poor habitat quality and the nematode community composition in the sewage polluted inside-harbor sediments required a longer time for recovery than samples from the better habitat quality and the nematode community composition in the outside-harbor sediments.  相似文献   

9.
ＷＡＴＥＲＱＵＡＬＩＴＹＡＮＡＬＹＳＩＳＡＮＤＡＳＳＥＳＳＭＥＮＴＯＦＲＩＶＥＲＳＩＮＪＩＬＩＮＰＲＯＶＩＮＣＥＯＦＣＨＩＮＡ￥ＷａｎｇＪｕｎ（王俊）ＺｈａｏＢａｏｚｈｏｎｇ（赵宝中）（ＤｅｐｏｒｔｍｅｎｔｏｆＥｎｖｉｒｏｎｍｅｎｔＳｃｉｅｎｃｅ，Ｎ...  相似文献   

10.
The Nanfei River(Anhui Province,China) is a severely polluted urban river that flows into Chaohu Lake.In the present study,sediments were collected from the river and analyzed for their heavy metal contents.Multivariate statistics and the fuzzy comprehensive assessment method were used to determine the sources of pollution,the current pollution status,and spatial and temporal variations in heavy metal pollution in sediments.The concentrations of arsenic(As),cadmium(Cd),chromium(Cr),copper(Cu),mercury(Hg),nickel(Ni),lead(Pb),and zinc(Zn) in sediments ranged from 5.67–113,0.08–40.2,41.6–524,15.5–460,0.03–4.84,13.5–180,18.8–250,and 47.9–1 996 mg/kg,and the average concentrations of each metal were 1.7,38.7,1.8,5.5,18.8,1.3,2.5,and 11.1 times greater than the background values,respectively.Multivariate statistical analysis demonstrated that Hg,Cu,Cr,Cd,and Ni may have originated from industrial activities,whereas As and Pb came from agricultural activities.The fuzzy comprehensive assessment method,based on the fuzzy mathematics theory,was used to obtain a detailed assessment of the sediment quality in the Nanfei River watershed.The results indicated that the pollution was moderate in the downstream tributaries of the Nianbu and Dianbu Rivers,but was severe in the main channel of the Nanfei River and in the upstream tributaries of the Sili and Banqiao Rivers.Therefore,sediments in the Nanfei River watershed are heavily polluted and urgent measures should be taken to remedy the status.  相似文献   

11.
Ecotourism aims to deliver the philosophy of sustainable development through environmental conservation as well as socio-economic development. Areas with rich biodiversity and scenic beauty, like the Indian Himalayan region, have been one of the major destination centers for nature lovers from historical time. In view of conserving the rich biodiversity and natural heritage of the Himalayan region 92 protected areas have been set aside, of these Nanda Devi Biosphere Reserve (NDBR) is a well known world heritage site. Over a period of time establishing NDBR has invited conflicts between the local people and reserve authorities on the management approaches and utilization criteria of the natural resources, especially banning the traditional bio-resource collection rights of local community, expeditions, trekking, and other anthropogenic activities in the core zones. The present study aims to understand and analyze the various people - park conflicts, and also to suggest ways to mitigate such conflicts in view of biodiversity conservation and improvement of economic status of local people by promoting ecotourism. With this view the study further discusses the various aspects of ecotourism, its pros and cons, and the avenues of developing appropriate strategies for promotion of ecotourism in buffer zone areas of NDBR.  相似文献   

12.
Roads are conspicuous components in a river landscape;however,their impacts on river landscape patterns and ecological processes have not been systematically studied at the watershed scale.In this paper,the Lancang River Valley in Yunnan Province,China was selected as a case to study road lateral disconnection and crossing impacts and identify river-road network interaction.This study was primarily focused on the road impacts on soil erosion intensity and patch density by using GIS analysis at different scales and explored their distribution with terrain factors.The results showed that river density revealed spatial autocorrelation although both of the roads and rivers were distributed unevenly in the valley.The lateral road(road curvature≥1.1)proportion correlated with soil erosion intensity(p 0.01)at the small sub-basin scale.Soil erosion intensity decreased with increasing lateral road buffer width.Light erosion generally accounted for a large proportion of the erosion in the lateral road buffer zones(1.0–4.0 km),while higher class lateral roads imposed greater impacts on soil erosion than lower class roads,which primarily had a moderate erosion level.In addition,the results of road-river intersection density indicated that road crossing impacts were significantly correlated with patch density at the small sub-basin scale.Topography factor(percent of slope25°in each sub-basin had a close relationship with the ratio of total length of road line with curvature value≥1.1 to the total number of intersections.The correlation(p 0.01)between road impacts and terrain factor revealed that topography affected the road impact distribution in the Lancang River Valley.  相似文献   

13.
1INTRODUCTION Since the 1750s, promoted by Industry Revolution and the rapid development of science and technology, large-scale urbanization swept over the world. So far, it isestimatedthatmorethan60%oftheriversin the world have been experienced high levels of human modifica- tion (ALLAN, 1995). River systems have now become oneofthemostdeeplyhuman-affectedecosystemsinthe earth. To approach the impact ofhuman activitieson riv- ersystem as a multidiscipline topic has been a focus of res…  相似文献   

14.
Comparing with lithofacies palaeogeography of several great plains, the authors analyzed four great plains in Quaternary diastrophism, the sedimentary facies, sedimentary environment and their evolution from the independent embryonic and river system of ancient Heilongjiang finally to the Halar highland, Songnen Plain, Sanjiang Plain, the Xingkai Lake Plain and various river systems, collected the unification outside the system of Heilongjiang River to release into the sea, south ancient Xialiao River finally piracy Dongliao River, Xialiao River had released into the sea the ancient water law vicissitude and the evolved rule.  相似文献   

15.
Comparing with lithofacies palaeogeography of several great plains,the authors analyzed four great plains in Quaternary diastrophism,the sedimentary facies,sedimentary environment and their evolution from the independent embryonic and river system of ancient Heilongjiang finally to the Halar highland,Songnen Plain,Sanjiang Plain,the Xingkai Lake Plain and various river systems,collected the unification outside the system of Heilongjiang River to release into the sea,south ancient Xialiao River finally piracy Dongliao River,Xialiao River had released into the sea the ancient water law vicissitude and the evolved rule.  相似文献   

16.
本文通过2007、2013和2016年3个时相的遥感影像,反演提取水体浊度信息,从较为宏观的角度分析了敖江流域大面积开发建设所引发的水土流失对敖江水质的影响。研究表明,2007年12月,敖江流域尚未有大面积开发,沿岸植被覆盖良好,江水浊度较低,平均约为23 NTU,分布比较均匀;2013年3月,敖江贵安新区处于开发建设期,特别是东雁-海峡段沿岸大片植被为工地裸土所代替,大量沙土流失至江中,使该段江水的浊度比上游高出3倍以上,平均浊度升高37 NTU,最大浊度差可达60 NTU,影响范围可至下游13 km;2016年9月,贵安新区建设基本成型,水土流失大幅减少,敖江整体浊度恢复相对均匀,但东雁-海峡段的平均浊度约39 NTU,仍高出上游5 NTU。其他分散的局部建设,是江水出现高浊度斑块的重要原因。浊度的上升,降低了水体含氧量,导致水质下降。当前中国城市化快速发展,伴随着大量的工程建设,其所致水土流失问题应引起足够重视,并在工程中采取必要控制措施,以降低其对沿江水质的影响。  相似文献   

17.
Wetland plant communities in the plateau lakes of Yunnan Province, China, have decreased significantly over the past decades. To better understand this degradation, we analyzed the processes and characteristics of changes in wetland plant communities in two of the largest lakes in Yunnan Province, Dianchi and Erhai lakes. We collected records of native and alien plant communities in the two lakes from literature published from the 1950s to current period. We calculated plant community types and their area in some historical periods when related data were reported, and analyzed the relationship between changes in plant communities and water pollution. In Dianchi Lake, 12 community types of native plant communities, covering over 80% of the surface in the 1950s and 1960s, were reduced to four types covering 2.4% by the late 2000s. Alien plant communities started to appear in the lake in the late 1970s, and have since come to cover 4.9% of the lake surface, thereby becoming dominant. In Erhai Lake, 16 community types of native plant communities, covering 47.1% of the lake surface in the late 1970s, declined to 10 community types, covering 9.3% of the surface, by the late 2000s. Alien plant communities appeared in the middle 1980s, and at present cover 0.7% of the surface area. It was indicated that changes in plant communities were significant related to water eutrophication. The area occupied by native and alien plant communities was, respectively, negatively and positively related to the content of nutrients in water. This showed lacustrine pollution played an important role in native plant loss and alien plant invasion in the two plateau lakes.  相似文献   

18.
ＴＨＥＥＦＦＥＣＴＳＯＦＴＨＥＴＨＲＥＥＧＯＲＧＥＳＰＲＯＪＥＣＴＯＮＥＣＯＬＯＧＹＡＮＤＥＮＶＩＲＯＮＭＥＮＴＸｉａＹｉｃｈｅｎｇ（夏宜铮）（ＩｎｓｔｉｔｕｔｅｏｆＨｙｄｒｏｂｉｏｌｏｇｙ，ｔｈｅＣｈｉｎｅｓｅＡｃａｄｅｍｙｏｆＳｃｉｅｎｃｅｓ，Ｗ...  相似文献   

19.
河源区边界是重要的国家基础地理信息之一,但除长江、黄河等大江大河外的我国大部分其他中小流域仍缺乏确切的河源区边界信息,需要科学划定河源区边界以支持流域水生态保护相关政策的规划与实施。对此,本文在确立河源区划分原则、明确划分依据的基础上,提出了基于多特征指标和层次聚类分析法的河源区边界划定方法。以沁河流域为研究案例,首先利用均值变点分析法计算沁河流域子流域提取的最佳汇流累积量分位数阈值为0.15%,再基于子流域的多特征指标运用层次聚类分析法最终确定河源区范围边界,并将该方法应用于长江、黄河流域进行验证分析。结果表明：① 基于多特征指标和层次聚类分析提取的沁河流域河源区范围处于河底比降法、水文站点方法得到的源区范围面积之间;② 该方法在长江、黄河流域河源区划分结果的交并比分别达到85.40%和79.99%,侧面验证了本文方法进行河源区边界划分的合理性与适用性。基于多特征指标和层次聚类分析的河源区边界自动划分方法可以简捷高效地识别缺乏明确河源区边界信息的流域河源区范围,为我国河源区生态安全屏障识别、水资源保护相关政策的规划和实施提供科学支撑。  相似文献   

20.
１ＩＮＴＲＯＤＵＣＴＩＯＮＳｅｖｅｒｅｗａｔｅｒｐｏｌｕｔｉｏｎａｎｄｗａｔｅｒｒｅｓｏｕｒｃｅｓｓｈｏｒｔａｇｅｓｈａｖｅｂｅｃｏｍｅｔｗｏｋｅｙｏｂｓｔｒｕｃｔｉｏｎｓｔｏｒｅａｌｉｚｅｓｕｓｔａｉｎａｂｌｅｕｔｉｌｉｚａｔｉｏｎｏｆｗａｔｅ...  相似文献   

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