Strukturchemische Eigenschaften und Spurenstoffverhalten in aquatischen Ökosystemen     

R. Koch 《洁净——土壤、空气、水》1982,10(6):535-549

  相似文献   

Foss: Wasser — Abwasser — Abfall,Lexikon von A—Z, 2. völlig überarbeitete Auflage. Stuttgart,Karl Krämer Verlag, 1980, 148 ca. S., 87 Abb., DM 26,—     

R. Koch 《洁净——土壤、空气、水》1983,11(4):486-486

  相似文献   

Hrsg.: B. Böhnke: Gewässerschutz — Wasser — Abwasser,Band 57. Gesellschaft zur Förderung der Siedlungswasserwirtschaft an d. RWTH Aachen, 1982. 446 Seiten,DM 40,—     

R. Koch 《洁净——土壤、空气、水》1983,11(4):487-488

  相似文献   

Monoclinal bending of strata over laccolithic intrusions     

F.G. Koch  A.M. Johnson  D.D. Pollard   《Tectonophysics》1981,74(3-4)

Sedimentary strata on top of some laccolithic intrusions are nearly horizontal and little deformed, but are bent into steeply dipping monoclinal flexures over the peripheries of these intrusions. This form of bending is not explained by previous theories of laccolithic intrusion, which predict either horizontal undeformed strata over the center and faulted strata around the periphery, or strata bent continuously into a dome. However, a slight generalization of these theories accomodates the observed form and contains the previous forms as special cases. A critical assumption is that the strength of contacts within a multilayered overburden is overcome locally by layer-parallel shear. If this strength is less than the strength of the layers themselves, then layers over the center remain bonded together and display negligible bending, whereas layers over the periphery slip over one another and are readily bent into a monoclinal flexure.  相似文献   

Persistence of clear-water,shallow-lake ecosystems: the role of protected areas and stable aquatic food webs     

William O. Hobbs  Kevin M. Theissen  Sean M. Hagen  Charles W. Bruchu  Ben C. Czeck  Joy M. Ramstack Hobbs  Kyle D. Zimmer 《Journal of Paleolimnology》2014,51(3):405-420

The roles of both landscape alteration and in-lake processes need to be considered in conservation strategies for shallow lakes in the prairie regions of North America. Here we focus on shallow lakes in west-central Minnesota, USA, highlighting the long-term ecological history and response to known landscape changes of a clear-water, macrophyte-dominated, shallow lake. Contemporary limnological data suggest the aquatic ecosystem has been very stable and fishless for the last ~15 years. Sediment proxies for primary production and ecological change confirm that a stable ecosystem likely prevailed for the last ~200 years. However, sedimentary indicators of catchment erosion detail a distinct response to land-use change during the conversion of native grassland to agricultural land, and following establishment of a protected waterfowl production area (WPA) around the lake. Post-WPA, the rate of sediment accrual decreased dramatically within 5–10 years and sources of organic matter were similar to those of the pre-settlement period. The aquatic ecosystem has been able to withstand nutrient enrichment and allochthonous inputs because stable trophic interactions have likely been in place for more than 200 years. We conclude that lack of hydrologic connectivity and isolated, small catchments are important factors in the promotion of clear-water shallow lake ecosystems, mainly because they prevent colonization by fish and associated ecological consequences. This study highlights the importance of managing both the landscape and in-lake processes to maintain stable, clear-water, shallow lakes.  相似文献   

Chemical properties of HULIS from three different environments     

T. B. Kristensen  L. Du  Q. T. Nguyen  J. K. Nøjgaard  C. Bender Koch  O. Faurskov Nielsen  A. G. Hallar  D. H. Lowenthal  B. Nekat  D. van Pinxteren  H. Herrmann  M. Glasius  H. G. Kjaergaard  M. Bilde 《Journal of Atmospheric Chemistry》2015,72(1):65-80

  相似文献   

Diversity,composition and host-species relationships of epiphytic orchids and ferns in two forests in Nepal   总被引：1，自引：0，他引：1  

Yagya P. Adhikari  Anton Fischer  Hagen S. Fischer  Maan B. Rokaya  Prakash Bhattarai  Axel Gruppe 《山地科学学报》2017,14(6):1065-1075

Epiphytic plant species are an important part of biological diversity. It is therefore essential to understand the distribution pattern and the factors influencing such patterns. The present study is aimed at observing the patterns of species richness, abundances and species composition of epiphytic orchids and ferns in two subtropical forests in Nepal. We also studied the relationship of host plants (Schima wallichii and Quercus lanata) and epiphyte species. Data were collected in Naudhara community forest (CF) and the national forest (NF) in Shivapuri Nagarjun National Park. The data were analyzed using univariate and multivariate tests. In total, we recorded 41 species of epiphytes (33 orchid and 8 fern species). Orchid species abundance is significantly higher in CF compared to NF. Orchid species richness and abundance increased with increasing southern aspect whereas it decreased with increasing canopy cover, and fern species richness increased with host bark roughness. Orchid abundance was positively correlated with increasing bark pH, stem size, tree age and tree height and negatively correlated with increasing steepness of the area. Likewise, fern abundances were high in places with high canopy cover, trees that were tall and big, but decreased with increasing altitude and southern aspect. The composition of the orchid and fern species was affected by altitude, aspect, canopy cover, DBH, number of forks and forest management types. We showed that the diversity of orchid and fern epiphytes is influenced by host characteristics as well as host types. The most important pre-requisite for a high epiphyte biodiversity is the presence of old respectively tall trees, independent of the recent protection status. This means: (i) for protection, e.g. in the frame of the national park declaration, such areas should be used which host such old tall trees; and (ii) also in managed forests and even in intensively used landscapes epiphytes can be protected by letting a certain number of trees be and by giving them space to grow old and tall.  相似文献