青藏高原冷湿地生态系统CH4排放量估算   总被引：3，自引：0，他引：3  

金会军  吴杰 《冰川冻土》1999,21(4):339-350

The areal extent of cold freshwater wetlands on the Tibetan Plateau is estimated to be 0.133×10 6 km 2, suggesting a significant methane potential. Methane fluxes from wet alpine meadows, peatlands, Hippuris vulgaris mires and secondary marshes were 43.18,12.96,-0.28 and 45.90 mg·m -2 ·d -1 , respectively, based on the transection studies at the Huashixia Permafrost Station from July to August 1996. Average CH 4 flux in the thaw season was extrapolated to be 5.68 g·m -2 according to the areal percentage of wetland areas in the Huashixia region. CH 4 fluxes at four fixed sites, representative of similar ecosystems, ranged from -19.384 to 347.15 mg·m -2 ·d -1 , and the average CH 4 fluxes varied from 6.54 to 71.97 mg·m -2 ·d -1 at each site from April to September 1997. CH 4 emissions at each site during the entire thaw season was estimated from 1.21 to 10.65 g·m -2 , displaying strong spatial variations. Seasonal variations of CH 4 fluxes were also observed at the four sites. It is found that CH 4 bursted in the early thaw season, and increased afterwards with rising soil temperatures. Episodic fluxes were observed in summer, which influenced the average CH 4 flux considerably. Annual CH 4 emissions from cold wetlands on the plateau were estimated at about 0.7～0.9 Tg based on the distribution of wetlands, representative CH 4 fluxes, and number of thaw days. The centers of CH 4 releasing are located in the sources of the Yangtze and Yellow Rivers, and Zoige Peatlands.  相似文献   

黄淮海平原封丘试区水生植被   总被引：2，自引：0，他引：2  

倪乐意  蔡庆华  黎道丰  刘瑞秋  伍焯田  梁彦龄 《湖泊科学》1995,7(4):357-364

对封丘试区水生植被的研究表明:挺水植物的种类少,但其分布和生物量在该地区占有绝对优势。在本地区的两大代表水体中其生物量(鲜重)可达2.9×10~(?)kg和0.13×10~(?)kg。沉水植物的分布面积在其中一个主要水体(曹岗湖)分布较广,但其生物量仅为3.2×10~3kg(鲜重),其生长的制约因素是水体中过多的草食性鱼类和水体过低的透明度。对植被中的主要经济种类芦苇的生长研究得出了其生物量与时间、密度和均长之间关系的函数。  相似文献   

Spatiotemporal variation of streambed quality and fine sediment deposition in five freshwater pearl mussel streams,in relation to extreme drought,strong rain and snow melt     

《Limnologica》2020

Oxygenated streambeds are considered a key requirement for the successful recruitment of stream fauna, including highly endangered freshwater pearl mussel Margaritifera margaritifera. Excessive amounts of fines impede exchange between open water and interstitial, leading to colmation and low oxygen levels in the juvenile habitat. Understanding the dynamic relationship between sediment delivery, transport, deposition and remobilization in relation to anthropogenic drivers is still poorly understood, yet is essential for conservation and restoration.This study analysed spatiotemporal sediment dynamics and interstitial habitat quality in five pearl mussel streams at the border region between Bavaria, Saxony and the Czech Republic during 2018 and 2019, comparing extremely dry periods with higher discharge events caused by snow melt and rainfall. Physicochemical habitat conditions within the streambed and sediment deposition were recorded in high spatial resolution along the stream courses, with a particular focus on the effects of tributaries and outflows of man-made fishponds.Habitat conditions were unsuitable for juvenile pearl mussels at the majority of sites, indicated by pronounced differences in physicochemical parameters between open water and the substrate, independent of discharge conditions. Sediment deposition varied markedly between discharge events, in terms of both the quality and quantity of deposits. Snow melt resulted in the highest sedimentation rates, but the smallest proportion of fine particles. During low flow conditions, fine sediment deposition was highly variable, ranging from 0.048 to 4.170 kg/week/m², mostly independent of flow velocity. High spatiotemporal variation was observed within and amongst stream systems, revealing different longitudinal patterns of fine sediment deposition, with catchment land use as the main driver. Temporal variability in sediment deposition was mainly associated with the discharge condition while abiotic parameters varied mainly with season.The high site-specificity of sedimentation rates and substrate conditions in response to different discharge events highlights the importance of an adapted conservation management which considers anthropogenic effects at the local scale.  相似文献   

Evaluating water quality for Amazonian streams along the interoceanic highway in Peru using macroinvertebrates collected by hand and with leaf packs     

《Limnologica》2020

We assessed water quality using physical, chemical, and biological characteristics in 37 streams between Puerto Maldonado and Cusco in Peru. Study sites ranged from ∼200 to 4000 m in elevation, with streams selected as pairs (control/natural vs. human impacted) along this gradient. In general, temperature decreased (R² = 0.82) and other parameters increased [dissolved oxygen (R² = 0.19), conductivity (R² = 0.17), pH (R² = 0.37)] with elevation. Macroinvertebrates were hand collected by professional entomologists and using leaf packs implemented by conservation workers. The professionals identified 213 unique taxa from the hand collections, with 80 species collected only one time. Data from control streams showed that as elevation increased, total richness (p = 0.008) and EPT richness (p = 0.050) decreased whereas Diptera richness increased (p = 0.002). NMS ordination indicated significant differences in macroinvertebrate assemblages when control streams from low and high elevations were contrasted. Hand collections also revealed significant differences between control and impact streams for total richness, EPT richness and % Diptera, but not for % EPT, % EPT richness, or % Diptera richness. The majority of the deployed leaf packs were successfully retrieved and contained many macroinvertebrates (Avg. = 141 individuals per pack). There were 98 unique taxa (family level or higher) identified from the leaf packs by the trained conservation workers. Fourteen of 15 macroinvertebrate community metrics (at the family level) were able to detect significant differences between control and impact sites. All of the family level metrics responded similarly across the elevation gradient except total richness, EPT richness, EPT count, and % Hydropsychids. Both the Costa Rica and the Virginia Save Our Stream Indexes were able to differentiate control from impacted streams using leaf pack data. Although the diversity of macroinvertebrates was higher for hand collections relative to leaf packs (due to greater habitats sampled and higher taxonomic resolution), leaf pack samples were better able to distinguish control from impacted streams. Specifically, leaf packs were able to discern impacts in streams at low elevation better than those at high elevation. Generally, macroinvertebrates indicated impact from urbanization to be worse than impacts from other human activities (i.e., gold mining and agriculture). Overall, hand collections will serve as an important reference of species diversity going forward while leaf packs processed by trained conservation workers are a viable method to monitor stream water quality in Peru and perhaps elsewhere.  相似文献   

深海化能生态系统大型生物多样性分布格局及其起源演化研究进展     

程娇  沙忠利  孙邵娥  惠敏 《海洋与湖沼》2021,52(2):508-521

深海被认为是地球上尚未被认识和开发的“最后疆域”,深海环境不仅可满足人类对未来资源的部分需求,还孕育出了独特的生态系统和特殊的生命过程。地球上绝大部分生态系统是利用光合作用来维持生命循环,而深海中存在着以化能合成为基础的生态系统。本文重点综述了国内外关于深海化能生态系统中大型生物多样性及其起源演化方面的研究进展,并对印太交汇区深海极端环境的生物多样性研究趋势和发展方向进行了展望。  相似文献   

Chemical and spectroscopic characterization of humic substances from sediment and riparian soil of a highly polluted urban river (Suquía River,Córdoba,Argentina)     

《国际泥沙研究》2020,35(3):287-294

The Suquia River,the largest urban river in Cordoba(Argentina),has been severely polluted for decades.Actions must be taken to restore its environmental quality by managing riparian zones for increased water-self purification.The current study aimed to characterize organic matter(OM) dynamics and humic substances(HS) spectrochemical properties along the lower-middle basin of the Suquia River.Riparian soil(0-20 cm) and sediment(0-10 cm) samples were collected from a reference location(S1)and four polluted sites(S2-S5) during a low-flow period.The contents of soil and sedimentary OM and HS fractions were analyzed by wet oxidation,as well as HS Fourier transform infrared(FT-IR) and ultraviolet-visible(UV-Vis) spectrochemical properties.The OM and HS fractions from riparian soil were high upstream of Cordoba City(S1 and S2,50.2-50.4 g/kg OM) and within a 50 km downstream location(S5,30.9 g/kg OM) owing to a surplus of fresh plant biomass-carbon(C) inputs.Highly heterogeneous sediment samples did not show any significant differences among sites(P 0.05).The lowest values of the ratio of absorbances at 465 and 665 nm(E4/E6)(1.78) and the Δ log K(0.15) coefficient(a measure of HS maturity degree) were obtained downstream of Cordoba City,for both riparian soil and sediment,indicating that HS were enriched by more condensed aromatic structures within highly degraded portions of the river.All samples exhibited similar IR spectra,implying overlapping recalcitrant-C structures at the functional group level,but with different absorbance intensity.Data from the current study constitute a baseline for understanding the chemical nature of HS from sediment and riparian soil along the Suquia River and can be used as a reference for future studies tracking OM compositional changes over time.  相似文献   

Re‐Connection of Oxbow Lakes as an Effective Measure of River Restoration     

《洁净——土壤、空气、水》2017,45(3)

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氮稳定同位素基准的可变性及对营养级评价的影响   总被引：10，自引：2，他引：8  

徐军  张敏  谢平 《湖泊科学》2010,22(1):8-20

稳定同位素技术已经成为生态学家研究生态系统特征与过程的重要手段之一。在利用稳定同位素研究植物-动物和动物之间的营养关系或者进行多生态系统的比较研究过程中,通常需要选择某种生物的稳定同位素作为"基准(baseline)"。同位素基准的目的是反映食物网生物最初物质来源的同位素特征。同位素基准的选择取决于具体研究问题与系统。本文综述了水域生态系统研究中初级生产者和初级消费者氮稳定同位素作为基准的应用。不同的研究都根据自身所关注的生态学问题对基准进行选择和校正。然而,找到适当的同位素基准取决于同位素基准种内、种间和时空上的同位素变化特征,同时还取决于所关注的生态学问题的时间、空间尺度。本文评估了季节性和种内的同位素变异性对消费者营养级位置的影响。质量平衡模型的计算结果说明同位素基准可变性可以显著影响对消费者营养级位置的评估。  相似文献   

基于随机森林模型的太湖水生植被遥感信息提取   总被引：3，自引：1，他引：2  

侍昊  李旭文  牛志春  李继影  李杨  李宁 《湖泊科学》2016,28(3):635-644

水生植被作为太湖湿地的重要组分,其数量和范围变化影响着湖泊生态系统的平衡,故利用遥感技术对水生植被的空间分布开展研究有助于太湖湿地生态系统的保护.以Landsat 8多光谱遥感影像为主要数据源,利用光谱指数和图像变换方法构建多个特征变量,结合随机森林(RF)模型,提取太湖水生植被的空间分布.结果表明:(1)通过对比分析训练样本特征值的平均值、标准差和变异系数,NDVI、NDWIF、SR等指数更易于区分开敞水域和沉水植被、浮叶植被和挺水植被;(2)当设置1000棵分类树和4个分割节点的随机变量时,RF分类模型的袋外误分率小于6%,误分主要受SR、MNDWI和NDVI等特征变量影响;(3)通过验证分析,基于RF模型获得的2014年7月太湖水生植被覆盖面积约为306.0km2,分类精度为88.56%(Kappa系数为0.88),主要分布在湖体的东部和南部,以沉水和浮叶植被为主,两者占水生植被覆盖总面积的84.9%.  相似文献   

Zielvorgaben für Pflanzenschutzmittelwirkstoffe und andere Schadstoffe in Oberflächengewässern     

Jutta Jahnel  Christian Zwiener  Thomas J. Gremm  Gudrun Abbt‐Braun  Fritz H. Frimmel  Carola Kussatz  Dieter Schudoma  Werner Rocker 《洁净——土壤、空气、水》2001,29(4):246-253

Quality Targets for Pesticides and Other Pollutants in Surface Waters Surface waters are not only adversely affected by industrial and municipal wastewaters but also by diffuse sources. For the control of the ecological water quality, so‐called quality targets are set. The quality targets are threshold concentrations for hazardous substances related to the protected goods like water ecosystems, drinking water supply, sediments, or fishing. In this paper, quality targets for the protection of aquatic life in surface waters were derived on the basis of a concept developed by the International Commission for the Protection of the Rhine (Internationale Kommission zum Schutze des Rheins – IKSR). The quality targets for the selected hazardous substances, which mainly belong to the chemical class of pesticides, were calculated using ecotoxicological results for species of bacteria, algae, fish, and small crustaceans, as the four trophic standards of the water ecosystem. In cooperation with the Federal Environmental Agency (Umweltbundesamt – UBA) the effect data were taken from ecotoxicological data bases. According to the concept of the IKSR, the lowest test result for the most sensitive species was multiplied by an assessment factor. This proceeding concerns the difficulty in describing the complex interactions in water ecosystems with toxicity data of single laboratory experiments for a few organisms. For seven pesticides quality targets below 0.1 μg/L were proposed. These results show that the ecotoxicologically based quality targets might be even lower than the limit values for pesticides in drinking water of 0.1 μg/L. But for most of the substances the determined values are significantly higher. The great concentration range of quality targets demonstrates distinctly that one standard concentration for all pesticides could not be given with regard to the different effects on aquatic organisms.  相似文献