云南独龙江流域植被概况

独龙江流域仅指贡山县一个行政乡的范围,独江龙(史称俅江)南北贯穿其间,     

Cryptosporidium Source Tracking in the Potomac River Watershed

To better characterize Cryptosporidium in the Potomac River watershed, a PCR-based genotyping tool was used to analyze 64 base flow and 28 storm flow samples from five sites in the watershed. These sites included two water treatment plant intakes, as well as three upstream sites, each associated with a different type of land use. The uses, including urban wastewater, agricultural (cattle) wastewater, and wildlife, posed different risks in terms of the potential contribution of Cryptosporidium oocysts to the source water. Cryptosporidium was detected in 27 base flow water samples and 23 storm flow water samples. The most frequently detected species was C. andersoni (detected in 41 samples), while 14 other species or genotypes, almost all wildlife associated, were occasionally detected. The two common human-pathogenic species, C. hominis and C. parvum, were not detected. Although C. andersoni was common at all four sites influenced by agriculture, it was largely absent at the urban wastewater site. There were very few positive samples as determined by Environmental Protection Agency method 1623 at any site; only 8 of 90 samples analyzed (9%) were positive for Cryptosporidium as determined by microscopy. The genotyping results suggest that many of the Cryptosporidium oocysts in the water treatment plant source waters were from old calves and adult cattle and might not pose a significant risk to human health.     

Asynchronous Changes in Vegetation,Runoff and Erosion in the Nile River Watershed during the Holocene

The termination of the African Humid Period in northeastern Africa during the early Holocene was marked by the southward migration of the rain belt and the disappearance of the Green Sahara. This interval of drastic environmental changes was also marked by the initiation of food production by North African hunter-gatherer populations and thus provides critical information on human-environment relationships. However, existing records of regional climatic and environmental changes exhibit large differences in timing and modes of the wet/dry transition at the end of the African Humid Period. Here we present independent records of changes in river runoff, vegetation and erosion in the Nile River watershed during the Holocene obtained from a unique sedimentary sequence on the Nile River fan using organic and inorganic proxy data. This high-resolution reconstruction allows to examine the phase relationship between the changes of these three parameters and provides a detailed picture of the environmental conditions during the Paleolithic/Neolithic transition. The data show that river runoff decreased gradually during the wet/arid transition at the end of the AHP whereas rapid shifts of vegetation and erosion occurred earlier between 8.7 and ∼6 ka BP. These asynchronous changes are compared to other regional records and provide new insights into the threshold responses of the environment to climatic changes. Our record demonstrates that the degradation of the environment in northeastern Africa was more abrupt and occurred earlier than previously thought and may have accelerated the process of domestication in order to secure sustainable food resources for the Neolithic African populations.     

Impact of Yangtze River Water Transfer on the Water Quality of the Lixia River Watershed,China

To improve water quality and reduce the negative impacts of sudden inputs of water pollution in the Lixia River watershed, China, a series of experimental water transfers from the Yangtze River to the Lixia River were conducted from 2 December 2006 to 7 January 2007. Water samples were collected every six days at 55 monitoring sites during this period. Eight water parameters (water temperature, pH, dissolved oxygen (DO), chemical oxygen demand (COD), potassium permanganate index (COD_Mn), ammonia nitrogen (NH₄ ⁺-N), electrical conductivity (EC), and water transparency (WT)) were analyzed to determine changes in nutrient concentrations during water transfers. The comprehensive pollution index (Pi) and single-factor (Si) evaluation methods were applied to evaluate spatio-temporal patterns of water quality during water transfers. Water quality parameters displayed different spatial and temporal distribution patterns within the watershed. Water quality was improved significantly by the water transfers, especially for sites closer to water intake points. The degree of improvement is positively related to rates of transfer inflow and drainage outflow. The effects differed for different water quality parameters at each site and at different water transfer times. There were notable decreases in NH₄ ⁺-N, DO, COD, and COD_Mn across the entire watershed. However, positive effects on EC and pH were not observed. It is concluded that freshwater transfers from the Yangtze River can be used as an emergency measure to flush pollutants from the Lixia River watershed. Improved understanding of the effects of water transfers on water quality can help the development and implementation of effective strategies to improve water quality within this watershed.     

Integrated assessment and changes of ecological environment in the Daning River Watershed

Based on Remote Sensing (RS), Geographical Information Systems (GIS), and the Spatial Principal Component Analysis (SPCA) method, the integrated assessment and changes in the ecological environment of Daning River Watershed are studied in this paper. The watershed is located in the Three Gorge Area in China. The result of the integrated assessment showed that level 9 had the biggest proportion in the year 1990, which was about 40%. In the year 2000, however, there were no levels with a proportion significantly bigger than the others. By comparing the assessment results in 1990 and 2000, it is discovered that the ecological environment in Daning River Watershed in 1990 was better than that in 2000. __________ Translated from Journal of Beijing Normal University (Natural Science), 2006, 42(2): 200–203 [译自: 北京师范大学学报 (自然科学版)]     

Integrated assessment and changes of ecological environment in the Daning River Watershed

Based on Remote Sensing (RS),Geographical Information Systems (GIS),and the Spatial Principal Component Analysis (SPCA) method,the integrated assessment and changes in the ecological environment of Daning River Watershed are studied in this paper.The watershed is located in the Three Gorge Area in China.The result of the integrated assessment showed that level 9 had the biggest proportion in the year 1990,which was about 40%.In the year 2000,however,there were no levels with a proportion significantly bigger than the others.By comparing the assessment results in 1990 and 2000,it is discovered that the ecological environment in Daning River Watershed in 1990 was better than that in 2000.     

山西桑干河流域湿地植被优势种群分布格局研究

根据野外调查的样地资料,应用方差/均值比（扩散系数）的t检验、聚集指数、平均拥挤度、聚块性指数、Green指数和负二项分布的聚集强度等方法,研究了山西桑干河流域湿地植被优势种群的分布格局并分析格局形成的原因,并用相关分析比较了6个指数间的关系,结果表明：这些植物的分布格局皆属于聚集分布,但它们的聚集强度有差异。聚集强度最大的是沙棘和柽柳,聚集强度最小的是小车前和车前,由于它们均分布于河漫滩或者河床地势较高处,土壤水分含量较低,仅仅在洪水季节短时间有积水存在,不是典型的湿地植物。典型的水生植物泽泻、莎草、轮藻、芦苇、香蒲、慈姑,湿生植物水葱、藨草等,它们的聚集强度居中,对水分有着较强的依赖性,均分布于流水较缓的河道,或者濒临河道的积水处。此外,多年生的莎草、芦苇、香蒲、水葱、藨草等主要依靠无性繁殖扩大种群分布范围和密度,这也是它们服从聚集分布的原因之一。本研究还说明方差/均值比率法是一种较好的分析种群分布格局的方法。     

Evaluation of the Degraded Riparian Ecosystems in the Geum River Watershed in Korea

Riparian vegetation, an important mediator of land–water interactions, provides habitat for animals and other organisms; however, riparian vegetation zones have been altered by agricultural and urban development in Korea. This riparian vegetation survey was conducted to obtain information vital for the ecological restoration and management of the Korean Geum River ecosystem. At 100 study sites, along the Geum River, we recorded the vegetation of the Geum riparian zone. We then surveyed the riparian vegetation associations in the area and overlaid those areas corresponding to trees, shrubs, perennial herbs, annual herbs, exotic plants, cultivated lands, and damaged lands on a geographical map. We also reconstructed the cross-sectional landscape. The mean values of vegetation diversity, exotic plant area (%), annual plant area (%), and species richness were 6.47 ± 0.26, 5.44 ± 1.01, 11.98 ± 1.20, and 22.69 ± 0.93, respectively. The landscape elements of the herbaceous plants were more spread out, compared with those of the woody plants, and 23 sites were composed strictly of herbs. Our results indicate significant differences in vegetation structure among the study sites. For example, at some sites, exotic plants, cultivated lands, and damaged lands dominated the landscape comprising 25.7, 62, and 68.9%, respectively, of the area. The riparian landscape reference model suggested by these results may be applied to studies of other well-conserved riparian zones. We propose that the material pathways and transport of organisms from land to water at Geum River depend on the patchy distribution of these diverse landscape elements.     

泾河流域自然植被分布规律的初步研究

以泾河流域为研究区,在实地考察的基础上,运用植物群落学传统的研究方法研究了流域内自然植被的地带性分布规律.研究结果表明:泾河流域的自然植被类型主要包括典型草原和疏林灌丛草原,且均为水平地带性植被.其中,典型草原是泾河流域分布面积最大的水平地带性植被;疏林灌丛草原则是呈水平地带分布的典型草原植被并分别向位于东西两侧的子午岭和六盘山山地延伸的过渡型植被类型,即水平地带性植被向垂直地带性植被过渡的植被类型.     

Artificial Sweeteners in a Large Canadian River Reflect Human Consumption in the Watershed

Artificial sweeteners have been widely incorporated in human food products for aid in weight loss regimes, dental health protection and dietary control of diabetes. Some of these widely used compounds can pass non-degraded through wastewater treatment systems and are subsequently discharged to groundwater and surface waters. Measurements of artificial sweeteners in rivers used for drinking water production are scarce. In order to determine the riverine concentrations of artificial sweeteners and their usefulness as a tracer of wastewater at the scale of an entire watershed, we analyzed samples from 23 sites along the entire length of the Grand River, a large river in Southern Ontario, Canada, that is impacted by agricultural activities and urban centres. Municipal water from household taps was also sampled from several cities within the Grand River Watershed. Cyclamate, saccharin, sucralose, and acesulfame were found in elevated concentrations despite high rates of biological activity, large daily cycles in dissolved oxygen and shallow river depth. The maximum concentrations that we measured for sucralose (21 µg/L), cyclamate (0.88 µg/L), and saccharin (7.2 µg/L) are the highest reported concentrations of these compounds in surface waters to date anywhere in the world. Acesulfame persists at concentrations that are up to several orders of magnitude above the detection limit over a distance of 300 km and it behaves conservatively in the river, recording the wastewater contribution from the cumulative population in the basin. Acesulfame is a reliable wastewater effluent tracer in rivers. Furthermore, it can be used to assess rates of nutrient assimilation, track wastewater plume dilution, separate human and animal waste contributions and determine the relative persistence of emerging contaminants in impacted watersheds where multiple sources confound the usefulness of other tracers. The effects of artificial sweeteners on aquatic biota in rivers and in the downstream Great Lakes are largely unknown.     

Use of Bivalve Metrics to Quantify Influences of Coal-related Activities in the Clinch River Watershed, Virginia

Previously, we reported that survivorship and growth of field-caged Asian clams (Corbicula fluminea [Müller]) were significantly reduced downstream of the wastewater effluent discharge of the Clinch River Plant (CRP), a coal-fired electric power-generating facility in Russell County, VA (USA). These findings warranted the present study, which investigated whether reduced survivorship and growth of transplanted C. fluminea were predictive of adverse effects on resident bivalves – most notably the Clinch River’s (CR’s) federally protected freshwater mussel fauna (Unionoidea). Thus, surveys of unionoid assemblages and C. fluminea population densities and age distributions were conducted to assess ecotoxicological effects on bivalve assemblages naturally occurring in the CR. Results of these surveys suggested that field bioassays with transplanted C. fluminea were predictive of in-stream C. fluminea densities and the presence/absence of indigenous unionoid assemblages. Relative to C. fluminea, additional field bioassays with a juvenile unionoid species (Villosa iris) native to the CR were less predictive of adverse effects on resident bivalves. Concurrence of transplant studies and in-stream surveys was evident at most study sites, particularly within 0.6 km downstream of the CRP effluent where resident bivalves were virtually non-existent relative to other stream sites having similar habitat conditions. Our findings indicate that in situ field bioassays with transplanted C. fluminea are valuable tools for predicting in stream occurrence and distribution of resident freshwater bivalves, and that field studies integrating multiple bivalve metrics may be useful for prioritizing source-reduction efforts in similar watersheds. Discrepancies observed for transplanted C. fluminea and V. iris have important implications to selection of bivalve species used in field bioassays and warrant further study.     

Campylobacter spp. Recovered from the Upper Oconee River Watershed, Georgia in a 4-Year Study

Waterways should be considered in the migration routes of Campylobacter, and the genus has been isolated from several water sources. Inferences on migration routes can be made from tracking genetic types in populations found in specific habitats and testing how they are linked to other types. Water samples were taken over a 4-year period from waterways in the Upper Oconee River Watershed, Georgia, to recover isolates of thermophilic Campylobacter. The isolates were typed by multilocus sequence typing (MLST) and analyzed to determine the overall diversity of Campylobacter in that environment. Forty-seven independent isolates were recovered from 560 samples (8.4 %). Two (~4 %) isolates were Campylobacter coli, three (~6 %) isolates were putatively identified as Campylobacter lari, and the remaining 42 (~90 %) were Campylobacter jejuni. The C. jejuni and C. coli isolates were typed by the Oxford MLST scheme. Thirty sequence types (STs) were identified including 13 STs that were not found before in the MLST database, including 24 novel alleles. Of the 17 previously described STs, 10 have been isolated from humans, 6 from environmental water, and 6 from wild birds (five types from multiple sources). Seven sites had multiple positive samples, and on two occasions, the same ST was isolated at the same site. The most common type was STST61 with four isolates, and the most common clonal complex was CC179 with nine isolates. CC179 has been commonly associated with environmental water. Although some Campylobacter STs that were found in the Oconee River engage in widespread migration, most are tightly associated with or unique to environmental water sources.     

Measuring variability in trophic status in the Lake Waco/Bosque River Watershed

Background

Nutrient management in rivers and streams is difficult due to the spatial and temporal variability of algal growth responses. The objectives of this project were to determine the spatial and seasonal in situ variability of trophic status in the Lake Waco/Bosque River watershed, determine the variability in the lotic ecosystem trophic status index (LETSI) at each site as indicators of the system's nutrient sensitivity, and determine if passive diffusion periphytometers could provide threshold algal responses to nutrient enrichment.

Methods

We used the passive diffusion periphytometer to measure in-situ nutrient limitation and trophic status at eight sites in five streams in the Lake Waco/Bosque River Watershed in north-central Texas from July 1997 through October 1998. The chlorophyll a production in the periphytometers was used as an indicator of baseline chlorophyll a productivity and of maximum primary productivity (MPP) in response to nutrient enrichment (nitrogen and phosphorus). We evaluated the lotic ecosystem trophic status index (LETSI) using the ratio of baseline primary productivity to MPP, and evaluated the trophic class of each site.

Results

The rivers and streams in the Lake Waco/Bosque River Watershed exhibited varying degrees of nutrient enrichment over the 18-month sampling period. The North Bosque River at the headwaters (NB-02) located below the Stephenville, Texas wastewater treatment outfall consistently exhibited the highest degree of water quality impact due to nutrient enrichment. Sites at the outlet of the watershed (NB-04 and NB-05) were the next most enriched sites. Trophic class varied for enriched sites over seasons.

Conclusion

Seasonality played a significant role in the trophic class and sensitivity of each site to nutrients. Managing rivers and streams for nutrients will require methods for measuring in situ responses and sensitivities to nutrient enrichment. Nutrient enrichment periphytometers show significant potential for use in nutrient gradient studies.     

Species and Biogeochemical Cycles of Organic Phosphorus in Sediments From a River With Different Aquatic Plants Located in Huaihe River Watershed,China

The results of phosphorus fractionation in the sediments from a contaminated river containing different aquatic plants, analyzed by solution ³¹P-NMR for Organic Phosphorus, showed that the concentration of Inorganic Phosphorus dominated in all species and Organic Phosphorus accounted for over 20% of Total Phosphorus. In general, orthophosphate was dominant in all the sampling sites. The proportion of Organic Phosphorus accounting for the Total Phosphorus in the sediments with different plant decreased in the following order: Paspalum distichum > Typha orientalis > Hydrilla verticillata. Phosphorus-accumulation ability of Paspalum distichum was obviously stronger than Typha orientalis and Hydrilla verticillata. The Organic Phosphorus was in aquatic plants dominated by humic-associated P (Hu-P), which converted to Inorganic Ohosphorus more significantly in submerged plants than in emerged plants. The sediment dominated by Paspalum distichum abundantly accumulated Organic Phosphorus in the orthophosphate monoester fraction. The degradation and mineralization of orthophosphate monoester was the important source of high Inorganic Phosphorus concentration and net primary productivity in Suoxu River. The Organic Phosphorus derived from Typha orientalis and Hydrilla verticillata was dramatically converted to Inorganic Phosphorus when the environmental factors varied.     

Seasonal and spatial variations of heavy metals in surface sediments collected from the Baoxiang River in the Dianchi Watershed,China

To explore potential ecological hazards due to heavy metals in the Dianchi Lake Watershed, a three-stage European Community Bureau of Reference (BCR) sequential extraction procedure was applied to examine the spatial distributions and relative speciation ratios of Zn, Cu, Ni, Pb, and Cr in Baoxiang River sediments during wet and dry seasons. The metal species have similar spatial variations during different seasons. In the upstream reaches of the Baoxiang River, heavy metals reside primarily in the non-extractable residual fraction (72–90%). In the midstream, the residual fraction (35–89%) remains dominant, but the extractable fraction increases, featuring especially notable increases in the reducible fraction (5–40%). Downstream, the Cu, Ni, Pb, and Cr residual fractions remain high (46–80%) and the extractable fractions increase rapidly; the Zn extractable fraction is quite high (65.5%). Anthropogenic sources drive changes in heavy metal speciation. Changes in the river environment, such as pH and oxidation-reduction potential, also affect speciation. The reducible fraction of heavy metals in Baoxiang River sediments is most sensitive to pH. Potential ecological risk assessments for these five elements indicate that risks from Zn and Pb are mild to moderate in the middle and lower reaches of the river.     

Ecosystem Health Assessment of the Jinghe River Watershed on the Huangtu Plateau

An improved Costanza model was developed to assess the health of the Jinhe River Watershed ecosystem. The watershed is located at the center of the Huangtu Plateau in China and has suffered a severe disturbance in the last few decades. Three indicators including vigor, organization, and resilience were calculated respectively by merging ground-based observations with remotely sensed data on a watershed scale. Health indices of 12 topographic sub-watersheds were calculated using a modified Costanza formula. Health evaluated results indicated that sub-watersheds in the Huangtu mountain region were relatively healthy ecosystems with scores over 0.673. The sub-watersheds in the loess mountain and the loess gully regions, e.g., Jinghe, Heihe, and Honghe regions, scored moderately; their evaluated value ranged from 0.505 to 0.606. The two sub-watersheds in the loess gully region and all sub-watersheds in the loess hilly region scored the lowest, less than 0.50 and were considered unhealthy ecosystems. It can be argued that the loess hilly region and the loess gully regions should be in primary consideration for ecological protection and rehabilitation. This study provided a possible quantitative model for ecological planning and landscape management with respect to topographic conditions in this area.     

Distribution and Characteristics of Listeria monocytogenes Isolates from Surface Waters of the South Nation River Watershed, Ontario, Canada

Listeria monocytogenes is a facultative intracellular pathogen thought to be widely distributed in the environment. We investigated the prevalence and characteristics of L. monocytogenes isolates from surface waters derived from catchments within the South Nation River watershed (Ontario, Canada). This watershed is dominated by urban and rural development, livestock and crop production, and wildlife habitats. From June to November 2005, a total of 314 surface water samples were collected biweekly from 22 discrete sampling sites characterized by various upstream land uses. Presumptive Listeria spp. were isolated using a selective enrichment and isolation procedure, and 75 L. monocytogenes isolates were identified based on colony morphology, hemolytic activity, and amplification of three pathogenicity genes: iap, inlA, and hlyA. Thirty-two of 314 (10%) surface water samples were positive for the presence of L. monocytogenes, but detection ranged between 0 and 27% depending on the sampling date. Isolates belonging to serovar group 1/2a, 3a (50%) and group 4b, 4d, 4e (32%) were dominant. L. monocytogenes populations were resolved into 13 EcoRI ribotypes and 21 ApaI and 21 AscI pulsotypes. These had Simpson indexes of discrimination of up to 0.885. Lineage I-related isolates were dominant (61%) during the summer, whereas lineage II isolates were dominant (77%) in the fall. Isolates were, on average, resistant to 6.1 ± 2.1 antibiotics out of 17 tested. Half of the L. monocytogenes isolates exhibited potential virulence linked to the production of a functional internalin A, and some isolates were found to be moderately to highly virulent by in vitro Caco-2 plaque formation assay (up to 28% of entry). There was a statistically significant link between the occurrence of L. monocytogenes and proximity to an upstream dairy farm and degree of cropped land. Our data indicate that L. monocytogenes is widespread in the studied catchments, where it could represent a public health issue related to agricultural land use.